1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select ARCH_USE_CMPXCHG_LOCKREF 32 select HAVE_ARCH_SOFT_DIRTY 33 select MODULES_USE_ELF_RELA 34 select NEED_DMA_MAP_STATE 35 select SWIOTLB 36 select ARCH_HAS_ELFCORE_COMPAT 37 select ZONE_DMA32 38 39config FORCE_DYNAMIC_FTRACE 40 def_bool y 41 depends on X86_32 42 depends on FUNCTION_TRACER 43 select DYNAMIC_FTRACE 44 help 45 We keep the static function tracing (!DYNAMIC_FTRACE) around 46 in order to test the non static function tracing in the 47 generic code, as other architectures still use it. But we 48 only need to keep it around for x86_64. No need to keep it 49 for x86_32. For x86_32, force DYNAMIC_FTRACE. 50# 51# Arch settings 52# 53# ( Note that options that are marked 'if X86_64' could in principle be 54# ported to 32-bit as well. ) 55# 56config X86 57 def_bool y 58 # 59 # Note: keep this list sorted alphabetically 60 # 61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 63 select ARCH_32BIT_OFF_T if X86_32 64 select ARCH_CLOCKSOURCE_INIT 65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 72 select ARCH_HAS_CACHE_LINE_SIZE 73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 74 select ARCH_HAS_CPU_FINALIZE_INIT 75 select ARCH_HAS_CURRENT_STACK_POINTER 76 select ARCH_HAS_DEBUG_VIRTUAL 77 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 78 select ARCH_HAS_DEVMEM_IS_ALLOWED 79 select ARCH_HAS_EARLY_DEBUG if KGDB 80 select ARCH_HAS_ELF_RANDOMIZE 81 select ARCH_HAS_FAST_MULTIPLIER 82 select ARCH_HAS_FORTIFY_SOURCE 83 select ARCH_HAS_GCOV_PROFILE_ALL 84 select ARCH_HAS_KCOV if X86_64 85 select ARCH_HAS_MEM_ENCRYPT 86 select ARCH_HAS_MEMBARRIER_SYNC_CORE 87 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 88 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 89 select ARCH_HAS_PMEM_API if X86_64 90 select ARCH_HAS_PTE_DEVMAP if X86_64 91 select ARCH_HAS_PTE_SPECIAL 92 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 93 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 94 select ARCH_HAS_COPY_MC if X86_64 95 select ARCH_HAS_SET_MEMORY 96 select ARCH_HAS_SET_DIRECT_MAP 97 select ARCH_HAS_STRICT_KERNEL_RWX 98 select ARCH_HAS_STRICT_MODULE_RWX 99 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 100 select ARCH_HAS_SYSCALL_WRAPPER 101 select ARCH_HAS_UBSAN_SANITIZE_ALL 102 select ARCH_HAS_DEBUG_WX 103 select ARCH_HAS_ZONE_DMA_SET if EXPERT 104 select ARCH_HAVE_NMI_SAFE_CMPXCHG 105 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 106 select ARCH_MIGHT_HAVE_PC_PARPORT 107 select ARCH_MIGHT_HAVE_PC_SERIO 108 select ARCH_STACKWALK 109 select ARCH_SUPPORTS_ACPI 110 select ARCH_SUPPORTS_ATOMIC_RMW 111 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 112 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 113 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 114 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 115 select ARCH_SUPPORTS_CFI_CLANG if X86_64 116 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 117 select ARCH_SUPPORTS_LTO_CLANG 118 select ARCH_SUPPORTS_LTO_CLANG_THIN 119 select ARCH_USE_BUILTIN_BSWAP 120 select ARCH_USE_MEMTEST 121 select ARCH_USE_QUEUED_RWLOCKS 122 select ARCH_USE_QUEUED_SPINLOCKS 123 select ARCH_USE_SYM_ANNOTATIONS 124 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 125 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 126 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 127 select ARCH_WANTS_NO_INSTR 128 select ARCH_WANT_GENERAL_HUGETLB 129 select ARCH_WANT_HUGE_PMD_SHARE 130 select ARCH_WANT_LD_ORPHAN_WARN 131 select ARCH_WANT_OPTIMIZE_VMEMMAP if X86_64 132 select ARCH_WANTS_THP_SWAP if X86_64 133 select ARCH_HAS_PARANOID_L1D_FLUSH 134 select BUILDTIME_TABLE_SORT 135 select CLKEVT_I8253 136 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 137 select CLOCKSOURCE_WATCHDOG 138 # Word-size accesses may read uninitialized data past the trailing \0 139 # in strings and cause false KMSAN reports. 140 select DCACHE_WORD_ACCESS if !KMSAN 141 select DYNAMIC_SIGFRAME 142 select EDAC_ATOMIC_SCRUB 143 select EDAC_SUPPORT 144 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 145 select GENERIC_CLOCKEVENTS_MIN_ADJUST 146 select GENERIC_CMOS_UPDATE 147 select GENERIC_CPU_AUTOPROBE 148 select GENERIC_CPU_VULNERABILITIES 149 select GENERIC_EARLY_IOREMAP 150 select GENERIC_ENTRY 151 select GENERIC_IOMAP 152 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 153 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 154 select GENERIC_IRQ_MIGRATION if SMP 155 select GENERIC_IRQ_PROBE 156 select GENERIC_IRQ_RESERVATION_MODE 157 select GENERIC_IRQ_SHOW 158 select GENERIC_PENDING_IRQ if SMP 159 select GENERIC_PTDUMP 160 select GENERIC_SMP_IDLE_THREAD 161 select GENERIC_TIME_VSYSCALL 162 select GENERIC_GETTIMEOFDAY 163 select GENERIC_VDSO_TIME_NS 164 select GUP_GET_PXX_LOW_HIGH if X86_PAE 165 select HARDIRQS_SW_RESEND 166 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 167 select HAS_IOPORT 168 select HAVE_ACPI_APEI if ACPI 169 select HAVE_ACPI_APEI_NMI if ACPI 170 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 171 select HAVE_ARCH_AUDITSYSCALL 172 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 173 select HAVE_ARCH_HUGE_VMALLOC if X86_64 174 select HAVE_ARCH_JUMP_LABEL 175 select HAVE_ARCH_JUMP_LABEL_RELATIVE 176 select HAVE_ARCH_KASAN if X86_64 177 select HAVE_ARCH_KASAN_VMALLOC if X86_64 178 select HAVE_ARCH_KFENCE 179 select HAVE_ARCH_KMSAN if X86_64 180 select HAVE_ARCH_KGDB 181 select HAVE_ARCH_MMAP_RND_BITS if MMU 182 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 183 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 184 select HAVE_ARCH_PREL32_RELOCATIONS 185 select HAVE_ARCH_SECCOMP_FILTER 186 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 187 select HAVE_ARCH_STACKLEAK 188 select HAVE_ARCH_TRACEHOOK 189 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 190 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 191 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 192 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 193 select HAVE_ARCH_VMAP_STACK if X86_64 194 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 195 select HAVE_ARCH_WITHIN_STACK_FRAMES 196 select HAVE_ASM_MODVERSIONS 197 select HAVE_CMPXCHG_DOUBLE 198 select HAVE_CMPXCHG_LOCAL 199 select HAVE_CONTEXT_TRACKING_USER if X86_64 200 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 201 select HAVE_C_RECORDMCOUNT 202 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 203 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 204 select HAVE_BUILDTIME_MCOUNT_SORT 205 select HAVE_DEBUG_KMEMLEAK 206 select HAVE_DMA_CONTIGUOUS 207 select HAVE_DYNAMIC_FTRACE 208 select HAVE_DYNAMIC_FTRACE_WITH_REGS 209 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 210 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 211 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 212 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 213 select HAVE_EBPF_JIT 214 select HAVE_EFFICIENT_UNALIGNED_ACCESS 215 select HAVE_EISA 216 select HAVE_EXIT_THREAD 217 select HAVE_FAST_GUP 218 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 219 select HAVE_FTRACE_MCOUNT_RECORD 220 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 221 select HAVE_FUNCTION_TRACER 222 select HAVE_GCC_PLUGINS 223 select HAVE_HW_BREAKPOINT 224 select HAVE_IOREMAP_PROT 225 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 226 select HAVE_IRQ_TIME_ACCOUNTING 227 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 228 select HAVE_KERNEL_BZIP2 229 select HAVE_KERNEL_GZIP 230 select HAVE_KERNEL_LZ4 231 select HAVE_KERNEL_LZMA 232 select HAVE_KERNEL_LZO 233 select HAVE_KERNEL_XZ 234 select HAVE_KERNEL_ZSTD 235 select HAVE_KPROBES 236 select HAVE_KPROBES_ON_FTRACE 237 select HAVE_FUNCTION_ERROR_INJECTION 238 select HAVE_KRETPROBES 239 select HAVE_RETHOOK 240 select HAVE_KVM 241 select HAVE_LIVEPATCH if X86_64 242 select HAVE_MIXED_BREAKPOINTS_REGS 243 select HAVE_MOD_ARCH_SPECIFIC 244 select HAVE_MOVE_PMD 245 select HAVE_MOVE_PUD 246 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 247 select HAVE_NMI 248 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 249 select HAVE_OBJTOOL if X86_64 250 select HAVE_OPTPROBES 251 select HAVE_PCSPKR_PLATFORM 252 select HAVE_PERF_EVENTS 253 select HAVE_PERF_EVENTS_NMI 254 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 255 select HAVE_PCI 256 select HAVE_PERF_REGS 257 select HAVE_PERF_USER_STACK_DUMP 258 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 259 select MMU_GATHER_MERGE_VMAS 260 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 261 select HAVE_REGS_AND_STACK_ACCESS_API 262 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 263 select HAVE_FUNCTION_ARG_ACCESS_API 264 select HAVE_SETUP_PER_CPU_AREA 265 select HAVE_SOFTIRQ_ON_OWN_STACK 266 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 267 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 268 select HAVE_STATIC_CALL 269 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 270 select HAVE_PREEMPT_DYNAMIC_CALL 271 select HAVE_RSEQ 272 select HAVE_RUST if X86_64 273 select HAVE_SYSCALL_TRACEPOINTS 274 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 275 select HAVE_UNSTABLE_SCHED_CLOCK 276 select HAVE_USER_RETURN_NOTIFIER 277 select HAVE_GENERIC_VDSO 278 select HOTPLUG_PARALLEL if SMP && X86_64 279 select HOTPLUG_SMT if SMP 280 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 281 select IRQ_FORCED_THREADING 282 select NEED_PER_CPU_EMBED_FIRST_CHUNK 283 select NEED_PER_CPU_PAGE_FIRST_CHUNK 284 select NEED_SG_DMA_LENGTH 285 select PCI_DOMAINS if PCI 286 select PCI_LOCKLESS_CONFIG if PCI 287 select PERF_EVENTS 288 select RTC_LIB 289 select RTC_MC146818_LIB 290 select SPARSE_IRQ 291 select SYSCTL_EXCEPTION_TRACE 292 select THREAD_INFO_IN_TASK 293 select TRACE_IRQFLAGS_SUPPORT 294 select TRACE_IRQFLAGS_NMI_SUPPORT 295 select USER_STACKTRACE_SUPPORT 296 select HAVE_ARCH_KCSAN if X86_64 297 select PROC_PID_ARCH_STATUS if PROC_FS 298 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 299 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 300 select FUNCTION_ALIGNMENT_4B 301 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 302 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 303 304config INSTRUCTION_DECODER 305 def_bool y 306 depends on KPROBES || PERF_EVENTS || UPROBES 307 308config OUTPUT_FORMAT 309 string 310 default "elf32-i386" if X86_32 311 default "elf64-x86-64" if X86_64 312 313config LOCKDEP_SUPPORT 314 def_bool y 315 316config STACKTRACE_SUPPORT 317 def_bool y 318 319config MMU 320 def_bool y 321 322config ARCH_MMAP_RND_BITS_MIN 323 default 28 if 64BIT 324 default 8 325 326config ARCH_MMAP_RND_BITS_MAX 327 default 32 if 64BIT 328 default 16 329 330config ARCH_MMAP_RND_COMPAT_BITS_MIN 331 default 8 332 333config ARCH_MMAP_RND_COMPAT_BITS_MAX 334 default 16 335 336config SBUS 337 bool 338 339config GENERIC_ISA_DMA 340 def_bool y 341 depends on ISA_DMA_API 342 343config GENERIC_CSUM 344 bool 345 default y if KMSAN || KASAN 346 347config GENERIC_BUG 348 def_bool y 349 depends on BUG 350 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 351 352config GENERIC_BUG_RELATIVE_POINTERS 353 bool 354 355config ARCH_MAY_HAVE_PC_FDC 356 def_bool y 357 depends on ISA_DMA_API 358 359config GENERIC_CALIBRATE_DELAY 360 def_bool y 361 362config ARCH_HAS_CPU_RELAX 363 def_bool y 364 365config ARCH_HIBERNATION_POSSIBLE 366 def_bool y 367 368config ARCH_SUSPEND_POSSIBLE 369 def_bool y 370 371config AUDIT_ARCH 372 def_bool y if X86_64 373 374config KASAN_SHADOW_OFFSET 375 hex 376 depends on KASAN 377 default 0xdffffc0000000000 378 379config HAVE_INTEL_TXT 380 def_bool y 381 depends on INTEL_IOMMU && ACPI 382 383config X86_32_SMP 384 def_bool y 385 depends on X86_32 && SMP 386 387config X86_64_SMP 388 def_bool y 389 depends on X86_64 && SMP 390 391config ARCH_SUPPORTS_UPROBES 392 def_bool y 393 394config FIX_EARLYCON_MEM 395 def_bool y 396 397config DYNAMIC_PHYSICAL_MASK 398 bool 399 400config PGTABLE_LEVELS 401 int 402 default 5 if X86_5LEVEL 403 default 4 if X86_64 404 default 3 if X86_PAE 405 default 2 406 407config CC_HAS_SANE_STACKPROTECTOR 408 bool 409 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 410 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 411 help 412 We have to make sure stack protector is unconditionally disabled if 413 the compiler produces broken code or if it does not let us control 414 the segment on 32-bit kernels. 415 416menu "Processor type and features" 417 418config SMP 419 bool "Symmetric multi-processing support" 420 help 421 This enables support for systems with more than one CPU. If you have 422 a system with only one CPU, say N. If you have a system with more 423 than one CPU, say Y. 424 425 If you say N here, the kernel will run on uni- and multiprocessor 426 machines, but will use only one CPU of a multiprocessor machine. If 427 you say Y here, the kernel will run on many, but not all, 428 uniprocessor machines. On a uniprocessor machine, the kernel 429 will run faster if you say N here. 430 431 Note that if you say Y here and choose architecture "586" or 432 "Pentium" under "Processor family", the kernel will not work on 486 433 architectures. Similarly, multiprocessor kernels for the "PPro" 434 architecture may not work on all Pentium based boards. 435 436 People using multiprocessor machines who say Y here should also say 437 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 438 Management" code will be disabled if you say Y here. 439 440 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 441 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 442 <http://www.tldp.org/docs.html#howto>. 443 444 If you don't know what to do here, say N. 445 446config X86_X2APIC 447 bool "Support x2apic" 448 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 449 help 450 This enables x2apic support on CPUs that have this feature. 451 452 This allows 32-bit apic IDs (so it can support very large systems), 453 and accesses the local apic via MSRs not via mmio. 454 455 Some Intel systems circa 2022 and later are locked into x2APIC mode 456 and can not fall back to the legacy APIC modes if SGX or TDX are 457 enabled in the BIOS. They will boot with very reduced functionality 458 without enabling this option. 459 460 If you don't know what to do here, say N. 461 462config X86_MPPARSE 463 bool "Enable MPS table" if ACPI 464 default y 465 depends on X86_LOCAL_APIC 466 help 467 For old smp systems that do not have proper acpi support. Newer systems 468 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 469 470config GOLDFISH 471 def_bool y 472 depends on X86_GOLDFISH 473 474config X86_CPU_RESCTRL 475 bool "x86 CPU resource control support" 476 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 477 select KERNFS 478 select PROC_CPU_RESCTRL if PROC_FS 479 help 480 Enable x86 CPU resource control support. 481 482 Provide support for the allocation and monitoring of system resources 483 usage by the CPU. 484 485 Intel calls this Intel Resource Director Technology 486 (Intel(R) RDT). More information about RDT can be found in the 487 Intel x86 Architecture Software Developer Manual. 488 489 AMD calls this AMD Platform Quality of Service (AMD QoS). 490 More information about AMD QoS can be found in the AMD64 Technology 491 Platform Quality of Service Extensions manual. 492 493 Say N if unsure. 494 495if X86_32 496config X86_BIGSMP 497 bool "Support for big SMP systems with more than 8 CPUs" 498 depends on SMP 499 help 500 This option is needed for the systems that have more than 8 CPUs. 501 502config X86_EXTENDED_PLATFORM 503 bool "Support for extended (non-PC) x86 platforms" 504 default y 505 help 506 If you disable this option then the kernel will only support 507 standard PC platforms. (which covers the vast majority of 508 systems out there.) 509 510 If you enable this option then you'll be able to select support 511 for the following (non-PC) 32 bit x86 platforms: 512 Goldfish (Android emulator) 513 AMD Elan 514 RDC R-321x SoC 515 SGI 320/540 (Visual Workstation) 516 STA2X11-based (e.g. Northville) 517 Moorestown MID devices 518 519 If you have one of these systems, or if you want to build a 520 generic distribution kernel, say Y here - otherwise say N. 521endif # X86_32 522 523if X86_64 524config X86_EXTENDED_PLATFORM 525 bool "Support for extended (non-PC) x86 platforms" 526 default y 527 help 528 If you disable this option then the kernel will only support 529 standard PC platforms. (which covers the vast majority of 530 systems out there.) 531 532 If you enable this option then you'll be able to select support 533 for the following (non-PC) 64 bit x86 platforms: 534 Numascale NumaChip 535 ScaleMP vSMP 536 SGI Ultraviolet 537 538 If you have one of these systems, or if you want to build a 539 generic distribution kernel, say Y here - otherwise say N. 540endif # X86_64 541# This is an alphabetically sorted list of 64 bit extended platforms 542# Please maintain the alphabetic order if and when there are additions 543config X86_NUMACHIP 544 bool "Numascale NumaChip" 545 depends on X86_64 546 depends on X86_EXTENDED_PLATFORM 547 depends on NUMA 548 depends on SMP 549 depends on X86_X2APIC 550 depends on PCI_MMCONFIG 551 help 552 Adds support for Numascale NumaChip large-SMP systems. Needed to 553 enable more than ~168 cores. 554 If you don't have one of these, you should say N here. 555 556config X86_VSMP 557 bool "ScaleMP vSMP" 558 select HYPERVISOR_GUEST 559 select PARAVIRT 560 depends on X86_64 && PCI 561 depends on X86_EXTENDED_PLATFORM 562 depends on SMP 563 help 564 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 565 supposed to run on these EM64T-based machines. Only choose this option 566 if you have one of these machines. 567 568config X86_UV 569 bool "SGI Ultraviolet" 570 depends on X86_64 571 depends on X86_EXTENDED_PLATFORM 572 depends on NUMA 573 depends on EFI 574 depends on KEXEC_CORE 575 depends on X86_X2APIC 576 depends on PCI 577 help 578 This option is needed in order to support SGI Ultraviolet systems. 579 If you don't have one of these, you should say N here. 580 581# Following is an alphabetically sorted list of 32 bit extended platforms 582# Please maintain the alphabetic order if and when there are additions 583 584config X86_GOLDFISH 585 bool "Goldfish (Virtual Platform)" 586 depends on X86_EXTENDED_PLATFORM 587 help 588 Enable support for the Goldfish virtual platform used primarily 589 for Android development. Unless you are building for the Android 590 Goldfish emulator say N here. 591 592config X86_INTEL_CE 593 bool "CE4100 TV platform" 594 depends on PCI 595 depends on PCI_GODIRECT 596 depends on X86_IO_APIC 597 depends on X86_32 598 depends on X86_EXTENDED_PLATFORM 599 select X86_REBOOTFIXUPS 600 select OF 601 select OF_EARLY_FLATTREE 602 help 603 Select for the Intel CE media processor (CE4100) SOC. 604 This option compiles in support for the CE4100 SOC for settop 605 boxes and media devices. 606 607config X86_INTEL_MID 608 bool "Intel MID platform support" 609 depends on X86_EXTENDED_PLATFORM 610 depends on X86_PLATFORM_DEVICES 611 depends on PCI 612 depends on X86_64 || (PCI_GOANY && X86_32) 613 depends on X86_IO_APIC 614 select I2C 615 select DW_APB_TIMER 616 select INTEL_SCU_PCI 617 help 618 Select to build a kernel capable of supporting Intel MID (Mobile 619 Internet Device) platform systems which do not have the PCI legacy 620 interfaces. If you are building for a PC class system say N here. 621 622 Intel MID platforms are based on an Intel processor and chipset which 623 consume less power than most of the x86 derivatives. 624 625config X86_INTEL_QUARK 626 bool "Intel Quark platform support" 627 depends on X86_32 628 depends on X86_EXTENDED_PLATFORM 629 depends on X86_PLATFORM_DEVICES 630 depends on X86_TSC 631 depends on PCI 632 depends on PCI_GOANY 633 depends on X86_IO_APIC 634 select IOSF_MBI 635 select INTEL_IMR 636 select COMMON_CLK 637 help 638 Select to include support for Quark X1000 SoC. 639 Say Y here if you have a Quark based system such as the Arduino 640 compatible Intel Galileo. 641 642config X86_INTEL_LPSS 643 bool "Intel Low Power Subsystem Support" 644 depends on X86 && ACPI && PCI 645 select COMMON_CLK 646 select PINCTRL 647 select IOSF_MBI 648 help 649 Select to build support for Intel Low Power Subsystem such as 650 found on Intel Lynxpoint PCH. Selecting this option enables 651 things like clock tree (common clock framework) and pincontrol 652 which are needed by the LPSS peripheral drivers. 653 654config X86_AMD_PLATFORM_DEVICE 655 bool "AMD ACPI2Platform devices support" 656 depends on ACPI 657 select COMMON_CLK 658 select PINCTRL 659 help 660 Select to interpret AMD specific ACPI device to platform device 661 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 662 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 663 implemented under PINCTRL subsystem. 664 665config IOSF_MBI 666 tristate "Intel SoC IOSF Sideband support for SoC platforms" 667 depends on PCI 668 help 669 This option enables sideband register access support for Intel SoC 670 platforms. On these platforms the IOSF sideband is used in lieu of 671 MSR's for some register accesses, mostly but not limited to thermal 672 and power. Drivers may query the availability of this device to 673 determine if they need the sideband in order to work on these 674 platforms. The sideband is available on the following SoC products. 675 This list is not meant to be exclusive. 676 - BayTrail 677 - Braswell 678 - Quark 679 680 You should say Y if you are running a kernel on one of these SoC's. 681 682config IOSF_MBI_DEBUG 683 bool "Enable IOSF sideband access through debugfs" 684 depends on IOSF_MBI && DEBUG_FS 685 help 686 Select this option to expose the IOSF sideband access registers (MCR, 687 MDR, MCRX) through debugfs to write and read register information from 688 different units on the SoC. This is most useful for obtaining device 689 state information for debug and analysis. As this is a general access 690 mechanism, users of this option would have specific knowledge of the 691 device they want to access. 692 693 If you don't require the option or are in doubt, say N. 694 695config X86_RDC321X 696 bool "RDC R-321x SoC" 697 depends on X86_32 698 depends on X86_EXTENDED_PLATFORM 699 select M486 700 select X86_REBOOTFIXUPS 701 help 702 This option is needed for RDC R-321x system-on-chip, also known 703 as R-8610-(G). 704 If you don't have one of these chips, you should say N here. 705 706config X86_32_NON_STANDARD 707 bool "Support non-standard 32-bit SMP architectures" 708 depends on X86_32 && SMP 709 depends on X86_EXTENDED_PLATFORM 710 help 711 This option compiles in the bigsmp and STA2X11 default 712 subarchitectures. It is intended for a generic binary 713 kernel. If you select them all, kernel will probe it one by 714 one and will fallback to default. 715 716# Alphabetically sorted list of Non standard 32 bit platforms 717 718config X86_SUPPORTS_MEMORY_FAILURE 719 def_bool y 720 # MCE code calls memory_failure(): 721 depends on X86_MCE 722 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 723 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 724 depends on X86_64 || !SPARSEMEM 725 select ARCH_SUPPORTS_MEMORY_FAILURE 726 727config STA2X11 728 bool "STA2X11 Companion Chip Support" 729 depends on X86_32_NON_STANDARD && PCI 730 select SWIOTLB 731 select MFD_STA2X11 732 select GPIOLIB 733 help 734 This adds support for boards based on the STA2X11 IO-Hub, 735 a.k.a. "ConneXt". The chip is used in place of the standard 736 PC chipset, so all "standard" peripherals are missing. If this 737 option is selected the kernel will still be able to boot on 738 standard PC machines. 739 740config X86_32_IRIS 741 tristate "Eurobraille/Iris poweroff module" 742 depends on X86_32 743 help 744 The Iris machines from EuroBraille do not have APM or ACPI support 745 to shut themselves down properly. A special I/O sequence is 746 needed to do so, which is what this module does at 747 kernel shutdown. 748 749 This is only for Iris machines from EuroBraille. 750 751 If unused, say N. 752 753config SCHED_OMIT_FRAME_POINTER 754 def_bool y 755 prompt "Single-depth WCHAN output" 756 depends on X86 757 help 758 Calculate simpler /proc/<PID>/wchan values. If this option 759 is disabled then wchan values will recurse back to the 760 caller function. This provides more accurate wchan values, 761 at the expense of slightly more scheduling overhead. 762 763 If in doubt, say "Y". 764 765menuconfig HYPERVISOR_GUEST 766 bool "Linux guest support" 767 help 768 Say Y here to enable options for running Linux under various hyper- 769 visors. This option enables basic hypervisor detection and platform 770 setup. 771 772 If you say N, all options in this submenu will be skipped and 773 disabled, and Linux guest support won't be built in. 774 775if HYPERVISOR_GUEST 776 777config PARAVIRT 778 bool "Enable paravirtualization code" 779 depends on HAVE_STATIC_CALL 780 help 781 This changes the kernel so it can modify itself when it is run 782 under a hypervisor, potentially improving performance significantly 783 over full virtualization. However, when run without a hypervisor 784 the kernel is theoretically slower and slightly larger. 785 786config PARAVIRT_XXL 787 bool 788 789config PARAVIRT_DEBUG 790 bool "paravirt-ops debugging" 791 depends on PARAVIRT && DEBUG_KERNEL 792 help 793 Enable to debug paravirt_ops internals. Specifically, BUG if 794 a paravirt_op is missing when it is called. 795 796config PARAVIRT_SPINLOCKS 797 bool "Paravirtualization layer for spinlocks" 798 depends on PARAVIRT && SMP 799 help 800 Paravirtualized spinlocks allow a pvops backend to replace the 801 spinlock implementation with something virtualization-friendly 802 (for example, block the virtual CPU rather than spinning). 803 804 It has a minimal impact on native kernels and gives a nice performance 805 benefit on paravirtualized KVM / Xen kernels. 806 807 If you are unsure how to answer this question, answer Y. 808 809config X86_HV_CALLBACK_VECTOR 810 def_bool n 811 812source "arch/x86/xen/Kconfig" 813 814config KVM_GUEST 815 bool "KVM Guest support (including kvmclock)" 816 depends on PARAVIRT 817 select PARAVIRT_CLOCK 818 select ARCH_CPUIDLE_HALTPOLL 819 select X86_HV_CALLBACK_VECTOR 820 default y 821 help 822 This option enables various optimizations for running under the KVM 823 hypervisor. It includes a paravirtualized clock, so that instead 824 of relying on a PIT (or probably other) emulation by the 825 underlying device model, the host provides the guest with 826 timing infrastructure such as time of day, and system time 827 828config ARCH_CPUIDLE_HALTPOLL 829 def_bool n 830 prompt "Disable host haltpoll when loading haltpoll driver" 831 help 832 If virtualized under KVM, disable host haltpoll. 833 834config PVH 835 bool "Support for running PVH guests" 836 help 837 This option enables the PVH entry point for guest virtual machines 838 as specified in the x86/HVM direct boot ABI. 839 840config PARAVIRT_TIME_ACCOUNTING 841 bool "Paravirtual steal time accounting" 842 depends on PARAVIRT 843 help 844 Select this option to enable fine granularity task steal time 845 accounting. Time spent executing other tasks in parallel with 846 the current vCPU is discounted from the vCPU power. To account for 847 that, there can be a small performance impact. 848 849 If in doubt, say N here. 850 851config PARAVIRT_CLOCK 852 bool 853 854config JAILHOUSE_GUEST 855 bool "Jailhouse non-root cell support" 856 depends on X86_64 && PCI 857 select X86_PM_TIMER 858 help 859 This option allows to run Linux as guest in a Jailhouse non-root 860 cell. You can leave this option disabled if you only want to start 861 Jailhouse and run Linux afterwards in the root cell. 862 863config ACRN_GUEST 864 bool "ACRN Guest support" 865 depends on X86_64 866 select X86_HV_CALLBACK_VECTOR 867 help 868 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 869 a flexible, lightweight reference open-source hypervisor, built with 870 real-time and safety-criticality in mind. It is built for embedded 871 IOT with small footprint and real-time features. More details can be 872 found in https://projectacrn.org/. 873 874config INTEL_TDX_GUEST 875 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 876 depends on X86_64 && CPU_SUP_INTEL 877 depends on X86_X2APIC 878 depends on EFI_STUB 879 select ARCH_HAS_CC_PLATFORM 880 select X86_MEM_ENCRYPT 881 select X86_MCE 882 select UNACCEPTED_MEMORY 883 help 884 Support running as a guest under Intel TDX. Without this support, 885 the guest kernel can not boot or run under TDX. 886 TDX includes memory encryption and integrity capabilities 887 which protect the confidentiality and integrity of guest 888 memory contents and CPU state. TDX guests are protected from 889 some attacks from the VMM. 890 891endif # HYPERVISOR_GUEST 892 893source "arch/x86/Kconfig.cpu" 894 895config HPET_TIMER 896 def_bool X86_64 897 prompt "HPET Timer Support" if X86_32 898 help 899 Use the IA-PC HPET (High Precision Event Timer) to manage 900 time in preference to the PIT and RTC, if a HPET is 901 present. 902 HPET is the next generation timer replacing legacy 8254s. 903 The HPET provides a stable time base on SMP 904 systems, unlike the TSC, but it is more expensive to access, 905 as it is off-chip. The interface used is documented 906 in the HPET spec, revision 1. 907 908 You can safely choose Y here. However, HPET will only be 909 activated if the platform and the BIOS support this feature. 910 Otherwise the 8254 will be used for timing services. 911 912 Choose N to continue using the legacy 8254 timer. 913 914config HPET_EMULATE_RTC 915 def_bool y 916 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 917 918# Mark as expert because too many people got it wrong. 919# The code disables itself when not needed. 920config DMI 921 default y 922 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 923 bool "Enable DMI scanning" if EXPERT 924 help 925 Enabled scanning of DMI to identify machine quirks. Say Y 926 here unless you have verified that your setup is not 927 affected by entries in the DMI blacklist. Required by PNP 928 BIOS code. 929 930config GART_IOMMU 931 bool "Old AMD GART IOMMU support" 932 select DMA_OPS 933 select IOMMU_HELPER 934 select SWIOTLB 935 depends on X86_64 && PCI && AMD_NB 936 help 937 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 938 GART based hardware IOMMUs. 939 940 The GART supports full DMA access for devices with 32-bit access 941 limitations, on systems with more than 3 GB. This is usually needed 942 for USB, sound, many IDE/SATA chipsets and some other devices. 943 944 Newer systems typically have a modern AMD IOMMU, supported via 945 the CONFIG_AMD_IOMMU=y config option. 946 947 In normal configurations this driver is only active when needed: 948 there's more than 3 GB of memory and the system contains a 949 32-bit limited device. 950 951 If unsure, say Y. 952 953config BOOT_VESA_SUPPORT 954 bool 955 help 956 If true, at least one selected framebuffer driver can take advantage 957 of VESA video modes set at an early boot stage via the vga= parameter. 958 959config MAXSMP 960 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 961 depends on X86_64 && SMP && DEBUG_KERNEL 962 select CPUMASK_OFFSTACK 963 help 964 Enable maximum number of CPUS and NUMA Nodes for this architecture. 965 If unsure, say N. 966 967# 968# The maximum number of CPUs supported: 969# 970# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 971# and which can be configured interactively in the 972# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 973# 974# The ranges are different on 32-bit and 64-bit kernels, depending on 975# hardware capabilities and scalability features of the kernel. 976# 977# ( If MAXSMP is enabled we just use the highest possible value and disable 978# interactive configuration. ) 979# 980 981config NR_CPUS_RANGE_BEGIN 982 int 983 default NR_CPUS_RANGE_END if MAXSMP 984 default 1 if !SMP 985 default 2 986 987config NR_CPUS_RANGE_END 988 int 989 depends on X86_32 990 default 64 if SMP && X86_BIGSMP 991 default 8 if SMP && !X86_BIGSMP 992 default 1 if !SMP 993 994config NR_CPUS_RANGE_END 995 int 996 depends on X86_64 997 default 8192 if SMP && CPUMASK_OFFSTACK 998 default 512 if SMP && !CPUMASK_OFFSTACK 999 default 1 if !SMP 1000 1001config NR_CPUS_DEFAULT 1002 int 1003 depends on X86_32 1004 default 32 if X86_BIGSMP 1005 default 8 if SMP 1006 default 1 if !SMP 1007 1008config NR_CPUS_DEFAULT 1009 int 1010 depends on X86_64 1011 default 8192 if MAXSMP 1012 default 64 if SMP 1013 default 1 if !SMP 1014 1015config NR_CPUS 1016 int "Maximum number of CPUs" if SMP && !MAXSMP 1017 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1018 default NR_CPUS_DEFAULT 1019 help 1020 This allows you to specify the maximum number of CPUs which this 1021 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1022 supported value is 8192, otherwise the maximum value is 512. The 1023 minimum value which makes sense is 2. 1024 1025 This is purely to save memory: each supported CPU adds about 8KB 1026 to the kernel image. 1027 1028config SCHED_CLUSTER 1029 bool "Cluster scheduler support" 1030 depends on SMP 1031 default y 1032 help 1033 Cluster scheduler support improves the CPU scheduler's decision 1034 making when dealing with machines that have clusters of CPUs. 1035 Cluster usually means a couple of CPUs which are placed closely 1036 by sharing mid-level caches, last-level cache tags or internal 1037 busses. 1038 1039config SCHED_SMT 1040 def_bool y if SMP 1041 1042config SCHED_MC 1043 def_bool y 1044 prompt "Multi-core scheduler support" 1045 depends on SMP 1046 help 1047 Multi-core scheduler support improves the CPU scheduler's decision 1048 making when dealing with multi-core CPU chips at a cost of slightly 1049 increased overhead in some places. If unsure say N here. 1050 1051config SCHED_MC_PRIO 1052 bool "CPU core priorities scheduler support" 1053 depends on SCHED_MC && CPU_SUP_INTEL 1054 select X86_INTEL_PSTATE 1055 select CPU_FREQ 1056 default y 1057 help 1058 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1059 core ordering determined at manufacturing time, which allows 1060 certain cores to reach higher turbo frequencies (when running 1061 single threaded workloads) than others. 1062 1063 Enabling this kernel feature teaches the scheduler about 1064 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1065 scheduler's CPU selection logic accordingly, so that higher 1066 overall system performance can be achieved. 1067 1068 This feature will have no effect on CPUs without this feature. 1069 1070 If unsure say Y here. 1071 1072config UP_LATE_INIT 1073 def_bool y 1074 depends on !SMP && X86_LOCAL_APIC 1075 1076config X86_UP_APIC 1077 bool "Local APIC support on uniprocessors" if !PCI_MSI 1078 default PCI_MSI 1079 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1080 help 1081 A local APIC (Advanced Programmable Interrupt Controller) is an 1082 integrated interrupt controller in the CPU. If you have a single-CPU 1083 system which has a processor with a local APIC, you can say Y here to 1084 enable and use it. If you say Y here even though your machine doesn't 1085 have a local APIC, then the kernel will still run with no slowdown at 1086 all. The local APIC supports CPU-generated self-interrupts (timer, 1087 performance counters), and the NMI watchdog which detects hard 1088 lockups. 1089 1090config X86_UP_IOAPIC 1091 bool "IO-APIC support on uniprocessors" 1092 depends on X86_UP_APIC 1093 help 1094 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1095 SMP-capable replacement for PC-style interrupt controllers. Most 1096 SMP systems and many recent uniprocessor systems have one. 1097 1098 If you have a single-CPU system with an IO-APIC, you can say Y here 1099 to use it. If you say Y here even though your machine doesn't have 1100 an IO-APIC, then the kernel will still run with no slowdown at all. 1101 1102config X86_LOCAL_APIC 1103 def_bool y 1104 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1105 select IRQ_DOMAIN_HIERARCHY 1106 1107config X86_IO_APIC 1108 def_bool y 1109 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1110 1111config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1112 bool "Reroute for broken boot IRQs" 1113 depends on X86_IO_APIC 1114 help 1115 This option enables a workaround that fixes a source of 1116 spurious interrupts. This is recommended when threaded 1117 interrupt handling is used on systems where the generation of 1118 superfluous "boot interrupts" cannot be disabled. 1119 1120 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1121 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1122 kernel does during interrupt handling). On chipsets where this 1123 boot IRQ generation cannot be disabled, this workaround keeps 1124 the original IRQ line masked so that only the equivalent "boot 1125 IRQ" is delivered to the CPUs. The workaround also tells the 1126 kernel to set up the IRQ handler on the boot IRQ line. In this 1127 way only one interrupt is delivered to the kernel. Otherwise 1128 the spurious second interrupt may cause the kernel to bring 1129 down (vital) interrupt lines. 1130 1131 Only affects "broken" chipsets. Interrupt sharing may be 1132 increased on these systems. 1133 1134config X86_MCE 1135 bool "Machine Check / overheating reporting" 1136 select GENERIC_ALLOCATOR 1137 default y 1138 help 1139 Machine Check support allows the processor to notify the 1140 kernel if it detects a problem (e.g. overheating, data corruption). 1141 The action the kernel takes depends on the severity of the problem, 1142 ranging from warning messages to halting the machine. 1143 1144config X86_MCELOG_LEGACY 1145 bool "Support for deprecated /dev/mcelog character device" 1146 depends on X86_MCE 1147 help 1148 Enable support for /dev/mcelog which is needed by the old mcelog 1149 userspace logging daemon. Consider switching to the new generation 1150 rasdaemon solution. 1151 1152config X86_MCE_INTEL 1153 def_bool y 1154 prompt "Intel MCE features" 1155 depends on X86_MCE && X86_LOCAL_APIC 1156 help 1157 Additional support for intel specific MCE features such as 1158 the thermal monitor. 1159 1160config X86_MCE_AMD 1161 def_bool y 1162 prompt "AMD MCE features" 1163 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1164 help 1165 Additional support for AMD specific MCE features such as 1166 the DRAM Error Threshold. 1167 1168config X86_ANCIENT_MCE 1169 bool "Support for old Pentium 5 / WinChip machine checks" 1170 depends on X86_32 && X86_MCE 1171 help 1172 Include support for machine check handling on old Pentium 5 or WinChip 1173 systems. These typically need to be enabled explicitly on the command 1174 line. 1175 1176config X86_MCE_THRESHOLD 1177 depends on X86_MCE_AMD || X86_MCE_INTEL 1178 def_bool y 1179 1180config X86_MCE_INJECT 1181 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1182 tristate "Machine check injector support" 1183 help 1184 Provide support for injecting machine checks for testing purposes. 1185 If you don't know what a machine check is and you don't do kernel 1186 QA it is safe to say n. 1187 1188source "arch/x86/events/Kconfig" 1189 1190config X86_LEGACY_VM86 1191 bool "Legacy VM86 support" 1192 depends on X86_32 1193 help 1194 This option allows user programs to put the CPU into V8086 1195 mode, which is an 80286-era approximation of 16-bit real mode. 1196 1197 Some very old versions of X and/or vbetool require this option 1198 for user mode setting. Similarly, DOSEMU will use it if 1199 available to accelerate real mode DOS programs. However, any 1200 recent version of DOSEMU, X, or vbetool should be fully 1201 functional even without kernel VM86 support, as they will all 1202 fall back to software emulation. Nevertheless, if you are using 1203 a 16-bit DOS program where 16-bit performance matters, vm86 1204 mode might be faster than emulation and you might want to 1205 enable this option. 1206 1207 Note that any app that works on a 64-bit kernel is unlikely to 1208 need this option, as 64-bit kernels don't, and can't, support 1209 V8086 mode. This option is also unrelated to 16-bit protected 1210 mode and is not needed to run most 16-bit programs under Wine. 1211 1212 Enabling this option increases the complexity of the kernel 1213 and slows down exception handling a tiny bit. 1214 1215 If unsure, say N here. 1216 1217config VM86 1218 bool 1219 default X86_LEGACY_VM86 1220 1221config X86_16BIT 1222 bool "Enable support for 16-bit segments" if EXPERT 1223 default y 1224 depends on MODIFY_LDT_SYSCALL 1225 help 1226 This option is required by programs like Wine to run 16-bit 1227 protected mode legacy code on x86 processors. Disabling 1228 this option saves about 300 bytes on i386, or around 6K text 1229 plus 16K runtime memory on x86-64, 1230 1231config X86_ESPFIX32 1232 def_bool y 1233 depends on X86_16BIT && X86_32 1234 1235config X86_ESPFIX64 1236 def_bool y 1237 depends on X86_16BIT && X86_64 1238 1239config X86_VSYSCALL_EMULATION 1240 bool "Enable vsyscall emulation" if EXPERT 1241 default y 1242 depends on X86_64 1243 help 1244 This enables emulation of the legacy vsyscall page. Disabling 1245 it is roughly equivalent to booting with vsyscall=none, except 1246 that it will also disable the helpful warning if a program 1247 tries to use a vsyscall. With this option set to N, offending 1248 programs will just segfault, citing addresses of the form 1249 0xffffffffff600?00. 1250 1251 This option is required by many programs built before 2013, and 1252 care should be used even with newer programs if set to N. 1253 1254 Disabling this option saves about 7K of kernel size and 1255 possibly 4K of additional runtime pagetable memory. 1256 1257config X86_IOPL_IOPERM 1258 bool "IOPERM and IOPL Emulation" 1259 default y 1260 help 1261 This enables the ioperm() and iopl() syscalls which are necessary 1262 for legacy applications. 1263 1264 Legacy IOPL support is an overbroad mechanism which allows user 1265 space aside of accessing all 65536 I/O ports also to disable 1266 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1267 capabilities and permission from potentially active security 1268 modules. 1269 1270 The emulation restricts the functionality of the syscall to 1271 only allowing the full range I/O port access, but prevents the 1272 ability to disable interrupts from user space which would be 1273 granted if the hardware IOPL mechanism would be used. 1274 1275config TOSHIBA 1276 tristate "Toshiba Laptop support" 1277 depends on X86_32 1278 help 1279 This adds a driver to safely access the System Management Mode of 1280 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1281 not work on models with a Phoenix BIOS. The System Management Mode 1282 is used to set the BIOS and power saving options on Toshiba portables. 1283 1284 For information on utilities to make use of this driver see the 1285 Toshiba Linux utilities web site at: 1286 <http://www.buzzard.org.uk/toshiba/>. 1287 1288 Say Y if you intend to run this kernel on a Toshiba portable. 1289 Say N otherwise. 1290 1291config X86_REBOOTFIXUPS 1292 bool "Enable X86 board specific fixups for reboot" 1293 depends on X86_32 1294 help 1295 This enables chipset and/or board specific fixups to be done 1296 in order to get reboot to work correctly. This is only needed on 1297 some combinations of hardware and BIOS. The symptom, for which 1298 this config is intended, is when reboot ends with a stalled/hung 1299 system. 1300 1301 Currently, the only fixup is for the Geode machines using 1302 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1303 1304 Say Y if you want to enable the fixup. Currently, it's safe to 1305 enable this option even if you don't need it. 1306 Say N otherwise. 1307 1308config MICROCODE 1309 bool "CPU microcode loading support" 1310 default y 1311 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1312 help 1313 If you say Y here, you will be able to update the microcode on 1314 Intel and AMD processors. The Intel support is for the IA32 family, 1315 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1316 AMD support is for families 0x10 and later. You will obviously need 1317 the actual microcode binary data itself which is not shipped with 1318 the Linux kernel. 1319 1320 The preferred method to load microcode from a detached initrd is described 1321 in Documentation/arch/x86/microcode.rst. For that you need to enable 1322 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1323 initrd for microcode blobs. 1324 1325 In addition, you can build the microcode into the kernel. For that you 1326 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1327 config option. 1328 1329config MICROCODE_INTEL 1330 bool "Intel microcode loading support" 1331 depends on CPU_SUP_INTEL && MICROCODE 1332 default MICROCODE 1333 help 1334 This options enables microcode patch loading support for Intel 1335 processors. 1336 1337 For the current Intel microcode data package go to 1338 <https://downloadcenter.intel.com> and search for 1339 'Linux Processor Microcode Data File'. 1340 1341config MICROCODE_AMD 1342 bool "AMD microcode loading support" 1343 depends on CPU_SUP_AMD && MICROCODE 1344 help 1345 If you select this option, microcode patch loading support for AMD 1346 processors will be enabled. 1347 1348config MICROCODE_LATE_LOADING 1349 bool "Late microcode loading (DANGEROUS)" 1350 default n 1351 depends on MICROCODE 1352 help 1353 Loading microcode late, when the system is up and executing instructions 1354 is a tricky business and should be avoided if possible. Just the sequence 1355 of synchronizing all cores and SMT threads is one fragile dance which does 1356 not guarantee that cores might not softlock after the loading. Therefore, 1357 use this at your own risk. Late loading taints the kernel too. 1358 1359config X86_MSR 1360 tristate "/dev/cpu/*/msr - Model-specific register support" 1361 help 1362 This device gives privileged processes access to the x86 1363 Model-Specific Registers (MSRs). It is a character device with 1364 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1365 MSR accesses are directed to a specific CPU on multi-processor 1366 systems. 1367 1368config X86_CPUID 1369 tristate "/dev/cpu/*/cpuid - CPU information support" 1370 help 1371 This device gives processes access to the x86 CPUID instruction to 1372 be executed on a specific processor. It is a character device 1373 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1374 /dev/cpu/31/cpuid. 1375 1376choice 1377 prompt "High Memory Support" 1378 default HIGHMEM4G 1379 depends on X86_32 1380 1381config NOHIGHMEM 1382 bool "off" 1383 help 1384 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1385 However, the address space of 32-bit x86 processors is only 4 1386 Gigabytes large. That means that, if you have a large amount of 1387 physical memory, not all of it can be "permanently mapped" by the 1388 kernel. The physical memory that's not permanently mapped is called 1389 "high memory". 1390 1391 If you are compiling a kernel which will never run on a machine with 1392 more than 1 Gigabyte total physical RAM, answer "off" here (default 1393 choice and suitable for most users). This will result in a "3GB/1GB" 1394 split: 3GB are mapped so that each process sees a 3GB virtual memory 1395 space and the remaining part of the 4GB virtual memory space is used 1396 by the kernel to permanently map as much physical memory as 1397 possible. 1398 1399 If the machine has between 1 and 4 Gigabytes physical RAM, then 1400 answer "4GB" here. 1401 1402 If more than 4 Gigabytes is used then answer "64GB" here. This 1403 selection turns Intel PAE (Physical Address Extension) mode on. 1404 PAE implements 3-level paging on IA32 processors. PAE is fully 1405 supported by Linux, PAE mode is implemented on all recent Intel 1406 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1407 then the kernel will not boot on CPUs that don't support PAE! 1408 1409 The actual amount of total physical memory will either be 1410 auto detected or can be forced by using a kernel command line option 1411 such as "mem=256M". (Try "man bootparam" or see the documentation of 1412 your boot loader (lilo or loadlin) about how to pass options to the 1413 kernel at boot time.) 1414 1415 If unsure, say "off". 1416 1417config HIGHMEM4G 1418 bool "4GB" 1419 help 1420 Select this if you have a 32-bit processor and between 1 and 4 1421 gigabytes of physical RAM. 1422 1423config HIGHMEM64G 1424 bool "64GB" 1425 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1426 select X86_PAE 1427 help 1428 Select this if you have a 32-bit processor and more than 4 1429 gigabytes of physical RAM. 1430 1431endchoice 1432 1433choice 1434 prompt "Memory split" if EXPERT 1435 default VMSPLIT_3G 1436 depends on X86_32 1437 help 1438 Select the desired split between kernel and user memory. 1439 1440 If the address range available to the kernel is less than the 1441 physical memory installed, the remaining memory will be available 1442 as "high memory". Accessing high memory is a little more costly 1443 than low memory, as it needs to be mapped into the kernel first. 1444 Note that increasing the kernel address space limits the range 1445 available to user programs, making the address space there 1446 tighter. Selecting anything other than the default 3G/1G split 1447 will also likely make your kernel incompatible with binary-only 1448 kernel modules. 1449 1450 If you are not absolutely sure what you are doing, leave this 1451 option alone! 1452 1453 config VMSPLIT_3G 1454 bool "3G/1G user/kernel split" 1455 config VMSPLIT_3G_OPT 1456 depends on !X86_PAE 1457 bool "3G/1G user/kernel split (for full 1G low memory)" 1458 config VMSPLIT_2G 1459 bool "2G/2G user/kernel split" 1460 config VMSPLIT_2G_OPT 1461 depends on !X86_PAE 1462 bool "2G/2G user/kernel split (for full 2G low memory)" 1463 config VMSPLIT_1G 1464 bool "1G/3G user/kernel split" 1465endchoice 1466 1467config PAGE_OFFSET 1468 hex 1469 default 0xB0000000 if VMSPLIT_3G_OPT 1470 default 0x80000000 if VMSPLIT_2G 1471 default 0x78000000 if VMSPLIT_2G_OPT 1472 default 0x40000000 if VMSPLIT_1G 1473 default 0xC0000000 1474 depends on X86_32 1475 1476config HIGHMEM 1477 def_bool y 1478 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1479 1480config X86_PAE 1481 bool "PAE (Physical Address Extension) Support" 1482 depends on X86_32 && !HIGHMEM4G 1483 select PHYS_ADDR_T_64BIT 1484 select SWIOTLB 1485 help 1486 PAE is required for NX support, and furthermore enables 1487 larger swapspace support for non-overcommit purposes. It 1488 has the cost of more pagetable lookup overhead, and also 1489 consumes more pagetable space per process. 1490 1491config X86_5LEVEL 1492 bool "Enable 5-level page tables support" 1493 default y 1494 select DYNAMIC_MEMORY_LAYOUT 1495 select SPARSEMEM_VMEMMAP 1496 depends on X86_64 1497 help 1498 5-level paging enables access to larger address space: 1499 up to 128 PiB of virtual address space and 4 PiB of 1500 physical address space. 1501 1502 It will be supported by future Intel CPUs. 1503 1504 A kernel with the option enabled can be booted on machines that 1505 support 4- or 5-level paging. 1506 1507 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1508 information. 1509 1510 Say N if unsure. 1511 1512config X86_DIRECT_GBPAGES 1513 def_bool y 1514 depends on X86_64 1515 help 1516 Certain kernel features effectively disable kernel 1517 linear 1 GB mappings (even if the CPU otherwise 1518 supports them), so don't confuse the user by printing 1519 that we have them enabled. 1520 1521config X86_CPA_STATISTICS 1522 bool "Enable statistic for Change Page Attribute" 1523 depends on DEBUG_FS 1524 help 1525 Expose statistics about the Change Page Attribute mechanism, which 1526 helps to determine the effectiveness of preserving large and huge 1527 page mappings when mapping protections are changed. 1528 1529config X86_MEM_ENCRYPT 1530 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1531 select DYNAMIC_PHYSICAL_MASK 1532 def_bool n 1533 1534config AMD_MEM_ENCRYPT 1535 bool "AMD Secure Memory Encryption (SME) support" 1536 depends on X86_64 && CPU_SUP_AMD 1537 depends on EFI_STUB 1538 select DMA_COHERENT_POOL 1539 select ARCH_USE_MEMREMAP_PROT 1540 select INSTRUCTION_DECODER 1541 select ARCH_HAS_CC_PLATFORM 1542 select X86_MEM_ENCRYPT 1543 select UNACCEPTED_MEMORY 1544 help 1545 Say yes to enable support for the encryption of system memory. 1546 This requires an AMD processor that supports Secure Memory 1547 Encryption (SME). 1548 1549config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1550 bool "Activate AMD Secure Memory Encryption (SME) by default" 1551 depends on AMD_MEM_ENCRYPT 1552 help 1553 Say yes to have system memory encrypted by default if running on 1554 an AMD processor that supports Secure Memory Encryption (SME). 1555 1556 If set to Y, then the encryption of system memory can be 1557 deactivated with the mem_encrypt=off command line option. 1558 1559 If set to N, then the encryption of system memory can be 1560 activated with the mem_encrypt=on command line option. 1561 1562# Common NUMA Features 1563config NUMA 1564 bool "NUMA Memory Allocation and Scheduler Support" 1565 depends on SMP 1566 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1567 default y if X86_BIGSMP 1568 select USE_PERCPU_NUMA_NODE_ID 1569 help 1570 Enable NUMA (Non-Uniform Memory Access) support. 1571 1572 The kernel will try to allocate memory used by a CPU on the 1573 local memory controller of the CPU and add some more 1574 NUMA awareness to the kernel. 1575 1576 For 64-bit this is recommended if the system is Intel Core i7 1577 (or later), AMD Opteron, or EM64T NUMA. 1578 1579 For 32-bit this is only needed if you boot a 32-bit 1580 kernel on a 64-bit NUMA platform. 1581 1582 Otherwise, you should say N. 1583 1584config AMD_NUMA 1585 def_bool y 1586 prompt "Old style AMD Opteron NUMA detection" 1587 depends on X86_64 && NUMA && PCI 1588 help 1589 Enable AMD NUMA node topology detection. You should say Y here if 1590 you have a multi processor AMD system. This uses an old method to 1591 read the NUMA configuration directly from the builtin Northbridge 1592 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1593 which also takes priority if both are compiled in. 1594 1595config X86_64_ACPI_NUMA 1596 def_bool y 1597 prompt "ACPI NUMA detection" 1598 depends on X86_64 && NUMA && ACPI && PCI 1599 select ACPI_NUMA 1600 help 1601 Enable ACPI SRAT based node topology detection. 1602 1603config NUMA_EMU 1604 bool "NUMA emulation" 1605 depends on NUMA 1606 help 1607 Enable NUMA emulation. A flat machine will be split 1608 into virtual nodes when booted with "numa=fake=N", where N is the 1609 number of nodes. This is only useful for debugging. 1610 1611config NODES_SHIFT 1612 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1613 range 1 10 1614 default "10" if MAXSMP 1615 default "6" if X86_64 1616 default "3" 1617 depends on NUMA 1618 help 1619 Specify the maximum number of NUMA Nodes available on the target 1620 system. Increases memory reserved to accommodate various tables. 1621 1622config ARCH_FLATMEM_ENABLE 1623 def_bool y 1624 depends on X86_32 && !NUMA 1625 1626config ARCH_SPARSEMEM_ENABLE 1627 def_bool y 1628 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1629 select SPARSEMEM_STATIC if X86_32 1630 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1631 1632config ARCH_SPARSEMEM_DEFAULT 1633 def_bool X86_64 || (NUMA && X86_32) 1634 1635config ARCH_SELECT_MEMORY_MODEL 1636 def_bool y 1637 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1638 1639config ARCH_MEMORY_PROBE 1640 bool "Enable sysfs memory/probe interface" 1641 depends on MEMORY_HOTPLUG 1642 help 1643 This option enables a sysfs memory/probe interface for testing. 1644 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1645 If you are unsure how to answer this question, answer N. 1646 1647config ARCH_PROC_KCORE_TEXT 1648 def_bool y 1649 depends on X86_64 && PROC_KCORE 1650 1651config ILLEGAL_POINTER_VALUE 1652 hex 1653 default 0 if X86_32 1654 default 0xdead000000000000 if X86_64 1655 1656config X86_PMEM_LEGACY_DEVICE 1657 bool 1658 1659config X86_PMEM_LEGACY 1660 tristate "Support non-standard NVDIMMs and ADR protected memory" 1661 depends on PHYS_ADDR_T_64BIT 1662 depends on BLK_DEV 1663 select X86_PMEM_LEGACY_DEVICE 1664 select NUMA_KEEP_MEMINFO if NUMA 1665 select LIBNVDIMM 1666 help 1667 Treat memory marked using the non-standard e820 type of 12 as used 1668 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1669 The kernel will offer these regions to the 'pmem' driver so 1670 they can be used for persistent storage. 1671 1672 Say Y if unsure. 1673 1674config HIGHPTE 1675 bool "Allocate 3rd-level pagetables from highmem" 1676 depends on HIGHMEM 1677 help 1678 The VM uses one page table entry for each page of physical memory. 1679 For systems with a lot of RAM, this can be wasteful of precious 1680 low memory. Setting this option will put user-space page table 1681 entries in high memory. 1682 1683config X86_CHECK_BIOS_CORRUPTION 1684 bool "Check for low memory corruption" 1685 help 1686 Periodically check for memory corruption in low memory, which 1687 is suspected to be caused by BIOS. Even when enabled in the 1688 configuration, it is disabled at runtime. Enable it by 1689 setting "memory_corruption_check=1" on the kernel command 1690 line. By default it scans the low 64k of memory every 60 1691 seconds; see the memory_corruption_check_size and 1692 memory_corruption_check_period parameters in 1693 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1694 1695 When enabled with the default parameters, this option has 1696 almost no overhead, as it reserves a relatively small amount 1697 of memory and scans it infrequently. It both detects corruption 1698 and prevents it from affecting the running system. 1699 1700 It is, however, intended as a diagnostic tool; if repeatable 1701 BIOS-originated corruption always affects the same memory, 1702 you can use memmap= to prevent the kernel from using that 1703 memory. 1704 1705config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1706 bool "Set the default setting of memory_corruption_check" 1707 depends on X86_CHECK_BIOS_CORRUPTION 1708 default y 1709 help 1710 Set whether the default state of memory_corruption_check is 1711 on or off. 1712 1713config MATH_EMULATION 1714 bool 1715 depends on MODIFY_LDT_SYSCALL 1716 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1717 help 1718 Linux can emulate a math coprocessor (used for floating point 1719 operations) if you don't have one. 486DX and Pentium processors have 1720 a math coprocessor built in, 486SX and 386 do not, unless you added 1721 a 487DX or 387, respectively. (The messages during boot time can 1722 give you some hints here ["man dmesg"].) Everyone needs either a 1723 coprocessor or this emulation. 1724 1725 If you don't have a math coprocessor, you need to say Y here; if you 1726 say Y here even though you have a coprocessor, the coprocessor will 1727 be used nevertheless. (This behavior can be changed with the kernel 1728 command line option "no387", which comes handy if your coprocessor 1729 is broken. Try "man bootparam" or see the documentation of your boot 1730 loader (lilo or loadlin) about how to pass options to the kernel at 1731 boot time.) This means that it is a good idea to say Y here if you 1732 intend to use this kernel on different machines. 1733 1734 More information about the internals of the Linux math coprocessor 1735 emulation can be found in <file:arch/x86/math-emu/README>. 1736 1737 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1738 kernel, it won't hurt. 1739 1740config MTRR 1741 def_bool y 1742 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1743 help 1744 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1745 the Memory Type Range Registers (MTRRs) may be used to control 1746 processor access to memory ranges. This is most useful if you have 1747 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1748 allows bus write transfers to be combined into a larger transfer 1749 before bursting over the PCI/AGP bus. This can increase performance 1750 of image write operations 2.5 times or more. Saying Y here creates a 1751 /proc/mtrr file which may be used to manipulate your processor's 1752 MTRRs. Typically the X server should use this. 1753 1754 This code has a reasonably generic interface so that similar 1755 control registers on other processors can be easily supported 1756 as well: 1757 1758 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1759 Registers (ARRs) which provide a similar functionality to MTRRs. For 1760 these, the ARRs are used to emulate the MTRRs. 1761 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1762 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1763 write-combining. All of these processors are supported by this code 1764 and it makes sense to say Y here if you have one of them. 1765 1766 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1767 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1768 can lead to all sorts of problems, so it's good to say Y here. 1769 1770 You can safely say Y even if your machine doesn't have MTRRs, you'll 1771 just add about 9 KB to your kernel. 1772 1773 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1774 1775config MTRR_SANITIZER 1776 def_bool y 1777 prompt "MTRR cleanup support" 1778 depends on MTRR 1779 help 1780 Convert MTRR layout from continuous to discrete, so X drivers can 1781 add writeback entries. 1782 1783 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1784 The largest mtrr entry size for a continuous block can be set with 1785 mtrr_chunk_size. 1786 1787 If unsure, say Y. 1788 1789config MTRR_SANITIZER_ENABLE_DEFAULT 1790 int "MTRR cleanup enable value (0-1)" 1791 range 0 1 1792 default "0" 1793 depends on MTRR_SANITIZER 1794 help 1795 Enable mtrr cleanup default value 1796 1797config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1798 int "MTRR cleanup spare reg num (0-7)" 1799 range 0 7 1800 default "1" 1801 depends on MTRR_SANITIZER 1802 help 1803 mtrr cleanup spare entries default, it can be changed via 1804 mtrr_spare_reg_nr=N on the kernel command line. 1805 1806config X86_PAT 1807 def_bool y 1808 prompt "x86 PAT support" if EXPERT 1809 depends on MTRR 1810 help 1811 Use PAT attributes to setup page level cache control. 1812 1813 PATs are the modern equivalents of MTRRs and are much more 1814 flexible than MTRRs. 1815 1816 Say N here if you see bootup problems (boot crash, boot hang, 1817 spontaneous reboots) or a non-working video driver. 1818 1819 If unsure, say Y. 1820 1821config ARCH_USES_PG_UNCACHED 1822 def_bool y 1823 depends on X86_PAT 1824 1825config X86_UMIP 1826 def_bool y 1827 prompt "User Mode Instruction Prevention" if EXPERT 1828 help 1829 User Mode Instruction Prevention (UMIP) is a security feature in 1830 some x86 processors. If enabled, a general protection fault is 1831 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1832 executed in user mode. These instructions unnecessarily expose 1833 information about the hardware state. 1834 1835 The vast majority of applications do not use these instructions. 1836 For the very few that do, software emulation is provided in 1837 specific cases in protected and virtual-8086 modes. Emulated 1838 results are dummy. 1839 1840config CC_HAS_IBT 1841 # GCC >= 9 and binutils >= 2.29 1842 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1843 # Clang/LLVM >= 14 1844 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1845 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1846 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1847 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1848 $(as-instr,endbr64) 1849 1850config X86_KERNEL_IBT 1851 prompt "Indirect Branch Tracking" 1852 def_bool y 1853 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1854 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1855 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1856 select OBJTOOL 1857 help 1858 Build the kernel with support for Indirect Branch Tracking, a 1859 hardware support course-grain forward-edge Control Flow Integrity 1860 protection. It enforces that all indirect calls must land on 1861 an ENDBR instruction, as such, the compiler will instrument the 1862 code with them to make this happen. 1863 1864 In addition to building the kernel with IBT, seal all functions that 1865 are not indirect call targets, avoiding them ever becoming one. 1866 1867 This requires LTO like objtool runs and will slow down the build. It 1868 does significantly reduce the number of ENDBR instructions in the 1869 kernel image. 1870 1871config X86_INTEL_MEMORY_PROTECTION_KEYS 1872 prompt "Memory Protection Keys" 1873 def_bool y 1874 # Note: only available in 64-bit mode 1875 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1876 select ARCH_USES_HIGH_VMA_FLAGS 1877 select ARCH_HAS_PKEYS 1878 help 1879 Memory Protection Keys provides a mechanism for enforcing 1880 page-based protections, but without requiring modification of the 1881 page tables when an application changes protection domains. 1882 1883 For details, see Documentation/core-api/protection-keys.rst 1884 1885 If unsure, say y. 1886 1887choice 1888 prompt "TSX enable mode" 1889 depends on CPU_SUP_INTEL 1890 default X86_INTEL_TSX_MODE_OFF 1891 help 1892 Intel's TSX (Transactional Synchronization Extensions) feature 1893 allows to optimize locking protocols through lock elision which 1894 can lead to a noticeable performance boost. 1895 1896 On the other hand it has been shown that TSX can be exploited 1897 to form side channel attacks (e.g. TAA) and chances are there 1898 will be more of those attacks discovered in the future. 1899 1900 Therefore TSX is not enabled by default (aka tsx=off). An admin 1901 might override this decision by tsx=on the command line parameter. 1902 Even with TSX enabled, the kernel will attempt to enable the best 1903 possible TAA mitigation setting depending on the microcode available 1904 for the particular machine. 1905 1906 This option allows to set the default tsx mode between tsx=on, =off 1907 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1908 details. 1909 1910 Say off if not sure, auto if TSX is in use but it should be used on safe 1911 platforms or on if TSX is in use and the security aspect of tsx is not 1912 relevant. 1913 1914config X86_INTEL_TSX_MODE_OFF 1915 bool "off" 1916 help 1917 TSX is disabled if possible - equals to tsx=off command line parameter. 1918 1919config X86_INTEL_TSX_MODE_ON 1920 bool "on" 1921 help 1922 TSX is always enabled on TSX capable HW - equals the tsx=on command 1923 line parameter. 1924 1925config X86_INTEL_TSX_MODE_AUTO 1926 bool "auto" 1927 help 1928 TSX is enabled on TSX capable HW that is believed to be safe against 1929 side channel attacks- equals the tsx=auto command line parameter. 1930endchoice 1931 1932config X86_SGX 1933 bool "Software Guard eXtensions (SGX)" 1934 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1935 depends on CRYPTO=y 1936 depends on CRYPTO_SHA256=y 1937 select MMU_NOTIFIER 1938 select NUMA_KEEP_MEMINFO if NUMA 1939 select XARRAY_MULTI 1940 help 1941 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1942 that can be used by applications to set aside private regions of code 1943 and data, referred to as enclaves. An enclave's private memory can 1944 only be accessed by code running within the enclave. Accesses from 1945 outside the enclave, including other enclaves, are disallowed by 1946 hardware. 1947 1948 If unsure, say N. 1949 1950config EFI 1951 bool "EFI runtime service support" 1952 depends on ACPI 1953 select UCS2_STRING 1954 select EFI_RUNTIME_WRAPPERS 1955 select ARCH_USE_MEMREMAP_PROT 1956 help 1957 This enables the kernel to use EFI runtime services that are 1958 available (such as the EFI variable services). 1959 1960 This option is only useful on systems that have EFI firmware. 1961 In addition, you should use the latest ELILO loader available 1962 at <http://elilo.sourceforge.net> in order to take advantage 1963 of EFI runtime services. However, even with this option, the 1964 resultant kernel should continue to boot on existing non-EFI 1965 platforms. 1966 1967config EFI_STUB 1968 bool "EFI stub support" 1969 depends on EFI 1970 select RELOCATABLE 1971 help 1972 This kernel feature allows a bzImage to be loaded directly 1973 by EFI firmware without the use of a bootloader. 1974 1975 See Documentation/admin-guide/efi-stub.rst for more information. 1976 1977config EFI_HANDOVER_PROTOCOL 1978 bool "EFI handover protocol (DEPRECATED)" 1979 depends on EFI_STUB 1980 default y 1981 help 1982 Select this in order to include support for the deprecated EFI 1983 handover protocol, which defines alternative entry points into the 1984 EFI stub. This is a practice that has no basis in the UEFI 1985 specification, and requires a priori knowledge on the part of the 1986 bootloader about Linux/x86 specific ways of passing the command line 1987 and initrd, and where in memory those assets may be loaded. 1988 1989 If in doubt, say Y. Even though the corresponding support is not 1990 present in upstream GRUB or other bootloaders, most distros build 1991 GRUB with numerous downstream patches applied, and may rely on the 1992 handover protocol as as result. 1993 1994config EFI_MIXED 1995 bool "EFI mixed-mode support" 1996 depends on EFI_STUB && X86_64 1997 help 1998 Enabling this feature allows a 64-bit kernel to be booted 1999 on a 32-bit firmware, provided that your CPU supports 64-bit 2000 mode. 2001 2002 Note that it is not possible to boot a mixed-mode enabled 2003 kernel via the EFI boot stub - a bootloader that supports 2004 the EFI handover protocol must be used. 2005 2006 If unsure, say N. 2007 2008config EFI_FAKE_MEMMAP 2009 bool "Enable EFI fake memory map" 2010 depends on EFI 2011 help 2012 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2013 this parameter, you can add arbitrary attribute to specific memory 2014 range by updating original (firmware provided) EFI memmap. This is 2015 useful for debugging of EFI memmap related feature, e.g., Address 2016 Range Mirroring feature. 2017 2018config EFI_MAX_FAKE_MEM 2019 int "maximum allowable number of ranges in efi_fake_mem boot option" 2020 depends on EFI_FAKE_MEMMAP 2021 range 1 128 2022 default 8 2023 help 2024 Maximum allowable number of ranges in efi_fake_mem boot option. 2025 Ranges can be set up to this value using comma-separated list. 2026 The default value is 8. 2027 2028config EFI_RUNTIME_MAP 2029 bool "Export EFI runtime maps to sysfs" if EXPERT 2030 depends on EFI 2031 default KEXEC_CORE 2032 help 2033 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2034 That memory map is required by the 2nd kernel to set up EFI virtual 2035 mappings after kexec, but can also be used for debugging purposes. 2036 2037 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2038 2039source "kernel/Kconfig.hz" 2040 2041config KEXEC 2042 bool "kexec system call" 2043 select KEXEC_CORE 2044 help 2045 kexec is a system call that implements the ability to shutdown your 2046 current kernel, and to start another kernel. It is like a reboot 2047 but it is independent of the system firmware. And like a reboot 2048 you can start any kernel with it, not just Linux. 2049 2050 The name comes from the similarity to the exec system call. 2051 2052 It is an ongoing process to be certain the hardware in a machine 2053 is properly shutdown, so do not be surprised if this code does not 2054 initially work for you. As of this writing the exact hardware 2055 interface is strongly in flux, so no good recommendation can be 2056 made. 2057 2058config KEXEC_FILE 2059 bool "kexec file based system call" 2060 select KEXEC_CORE 2061 select HAVE_IMA_KEXEC if IMA 2062 depends on X86_64 2063 depends on CRYPTO=y 2064 depends on CRYPTO_SHA256=y 2065 help 2066 This is new version of kexec system call. This system call is 2067 file based and takes file descriptors as system call argument 2068 for kernel and initramfs as opposed to list of segments as 2069 accepted by previous system call. 2070 2071config ARCH_HAS_KEXEC_PURGATORY 2072 def_bool KEXEC_FILE 2073 2074config KEXEC_SIG 2075 bool "Verify kernel signature during kexec_file_load() syscall" 2076 depends on KEXEC_FILE 2077 help 2078 2079 This option makes the kexec_file_load() syscall check for a valid 2080 signature of the kernel image. The image can still be loaded without 2081 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2082 there's a signature that we can check, then it must be valid. 2083 2084 In addition to this option, you need to enable signature 2085 verification for the corresponding kernel image type being 2086 loaded in order for this to work. 2087 2088config KEXEC_SIG_FORCE 2089 bool "Require a valid signature in kexec_file_load() syscall" 2090 depends on KEXEC_SIG 2091 help 2092 This option makes kernel signature verification mandatory for 2093 the kexec_file_load() syscall. 2094 2095config KEXEC_BZIMAGE_VERIFY_SIG 2096 bool "Enable bzImage signature verification support" 2097 depends on KEXEC_SIG 2098 depends on SIGNED_PE_FILE_VERIFICATION 2099 select SYSTEM_TRUSTED_KEYRING 2100 help 2101 Enable bzImage signature verification support. 2102 2103config CRASH_DUMP 2104 bool "kernel crash dumps" 2105 depends on X86_64 || (X86_32 && HIGHMEM) 2106 help 2107 Generate crash dump after being started by kexec. 2108 This should be normally only set in special crash dump kernels 2109 which are loaded in the main kernel with kexec-tools into 2110 a specially reserved region and then later executed after 2111 a crash by kdump/kexec. The crash dump kernel must be compiled 2112 to a memory address not used by the main kernel or BIOS using 2113 PHYSICAL_START, or it must be built as a relocatable image 2114 (CONFIG_RELOCATABLE=y). 2115 For more details see Documentation/admin-guide/kdump/kdump.rst 2116 2117config KEXEC_JUMP 2118 bool "kexec jump" 2119 depends on KEXEC && HIBERNATION 2120 help 2121 Jump between original kernel and kexeced kernel and invoke 2122 code in physical address mode via KEXEC 2123 2124config PHYSICAL_START 2125 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2126 default "0x1000000" 2127 help 2128 This gives the physical address where the kernel is loaded. 2129 2130 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2131 bzImage will decompress itself to above physical address and 2132 run from there. Otherwise, bzImage will run from the address where 2133 it has been loaded by the boot loader and will ignore above physical 2134 address. 2135 2136 In normal kdump cases one does not have to set/change this option 2137 as now bzImage can be compiled as a completely relocatable image 2138 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2139 address. This option is mainly useful for the folks who don't want 2140 to use a bzImage for capturing the crash dump and want to use a 2141 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2142 to be specifically compiled to run from a specific memory area 2143 (normally a reserved region) and this option comes handy. 2144 2145 So if you are using bzImage for capturing the crash dump, 2146 leave the value here unchanged to 0x1000000 and set 2147 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2148 for capturing the crash dump change this value to start of 2149 the reserved region. In other words, it can be set based on 2150 the "X" value as specified in the "crashkernel=YM@XM" 2151 command line boot parameter passed to the panic-ed 2152 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2153 for more details about crash dumps. 2154 2155 Usage of bzImage for capturing the crash dump is recommended as 2156 one does not have to build two kernels. Same kernel can be used 2157 as production kernel and capture kernel. Above option should have 2158 gone away after relocatable bzImage support is introduced. But it 2159 is present because there are users out there who continue to use 2160 vmlinux for dump capture. This option should go away down the 2161 line. 2162 2163 Don't change this unless you know what you are doing. 2164 2165config RELOCATABLE 2166 bool "Build a relocatable kernel" 2167 default y 2168 help 2169 This builds a kernel image that retains relocation information 2170 so it can be loaded someplace besides the default 1MB. 2171 The relocations tend to make the kernel binary about 10% larger, 2172 but are discarded at runtime. 2173 2174 One use is for the kexec on panic case where the recovery kernel 2175 must live at a different physical address than the primary 2176 kernel. 2177 2178 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2179 it has been loaded at and the compile time physical address 2180 (CONFIG_PHYSICAL_START) is used as the minimum location. 2181 2182config RANDOMIZE_BASE 2183 bool "Randomize the address of the kernel image (KASLR)" 2184 depends on RELOCATABLE 2185 default y 2186 help 2187 In support of Kernel Address Space Layout Randomization (KASLR), 2188 this randomizes the physical address at which the kernel image 2189 is decompressed and the virtual address where the kernel 2190 image is mapped, as a security feature that deters exploit 2191 attempts relying on knowledge of the location of kernel 2192 code internals. 2193 2194 On 64-bit, the kernel physical and virtual addresses are 2195 randomized separately. The physical address will be anywhere 2196 between 16MB and the top of physical memory (up to 64TB). The 2197 virtual address will be randomized from 16MB up to 1GB (9 bits 2198 of entropy). Note that this also reduces the memory space 2199 available to kernel modules from 1.5GB to 1GB. 2200 2201 On 32-bit, the kernel physical and virtual addresses are 2202 randomized together. They will be randomized from 16MB up to 2203 512MB (8 bits of entropy). 2204 2205 Entropy is generated using the RDRAND instruction if it is 2206 supported. If RDTSC is supported, its value is mixed into 2207 the entropy pool as well. If neither RDRAND nor RDTSC are 2208 supported, then entropy is read from the i8254 timer. The 2209 usable entropy is limited by the kernel being built using 2210 2GB addressing, and that PHYSICAL_ALIGN must be at a 2211 minimum of 2MB. As a result, only 10 bits of entropy are 2212 theoretically possible, but the implementations are further 2213 limited due to memory layouts. 2214 2215 If unsure, say Y. 2216 2217# Relocation on x86 needs some additional build support 2218config X86_NEED_RELOCS 2219 def_bool y 2220 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2221 2222config PHYSICAL_ALIGN 2223 hex "Alignment value to which kernel should be aligned" 2224 default "0x200000" 2225 range 0x2000 0x1000000 if X86_32 2226 range 0x200000 0x1000000 if X86_64 2227 help 2228 This value puts the alignment restrictions on physical address 2229 where kernel is loaded and run from. Kernel is compiled for an 2230 address which meets above alignment restriction. 2231 2232 If bootloader loads the kernel at a non-aligned address and 2233 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2234 address aligned to above value and run from there. 2235 2236 If bootloader loads the kernel at a non-aligned address and 2237 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2238 load address and decompress itself to the address it has been 2239 compiled for and run from there. The address for which kernel is 2240 compiled already meets above alignment restrictions. Hence the 2241 end result is that kernel runs from a physical address meeting 2242 above alignment restrictions. 2243 2244 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2245 this value must be a multiple of 0x200000. 2246 2247 Don't change this unless you know what you are doing. 2248 2249config DYNAMIC_MEMORY_LAYOUT 2250 bool 2251 help 2252 This option makes base addresses of vmalloc and vmemmap as well as 2253 __PAGE_OFFSET movable during boot. 2254 2255config RANDOMIZE_MEMORY 2256 bool "Randomize the kernel memory sections" 2257 depends on X86_64 2258 depends on RANDOMIZE_BASE 2259 select DYNAMIC_MEMORY_LAYOUT 2260 default RANDOMIZE_BASE 2261 help 2262 Randomizes the base virtual address of kernel memory sections 2263 (physical memory mapping, vmalloc & vmemmap). This security feature 2264 makes exploits relying on predictable memory locations less reliable. 2265 2266 The order of allocations remains unchanged. Entropy is generated in 2267 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2268 configuration have in average 30,000 different possible virtual 2269 addresses for each memory section. 2270 2271 If unsure, say Y. 2272 2273config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2274 hex "Physical memory mapping padding" if EXPERT 2275 depends on RANDOMIZE_MEMORY 2276 default "0xa" if MEMORY_HOTPLUG 2277 default "0x0" 2278 range 0x1 0x40 if MEMORY_HOTPLUG 2279 range 0x0 0x40 2280 help 2281 Define the padding in terabytes added to the existing physical 2282 memory size during kernel memory randomization. It is useful 2283 for memory hotplug support but reduces the entropy available for 2284 address randomization. 2285 2286 If unsure, leave at the default value. 2287 2288config ADDRESS_MASKING 2289 bool "Linear Address Masking support" 2290 depends on X86_64 2291 help 2292 Linear Address Masking (LAM) modifies the checking that is applied 2293 to 64-bit linear addresses, allowing software to use of the 2294 untranslated address bits for metadata. 2295 2296 The capability can be used for efficient address sanitizers (ASAN) 2297 implementation and for optimizations in JITs. 2298 2299config HOTPLUG_CPU 2300 def_bool y 2301 depends on SMP 2302 2303config COMPAT_VDSO 2304 def_bool n 2305 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2306 depends on COMPAT_32 2307 help 2308 Certain buggy versions of glibc will crash if they are 2309 presented with a 32-bit vDSO that is not mapped at the address 2310 indicated in its segment table. 2311 2312 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2313 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2314 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2315 the only released version with the bug, but OpenSUSE 9 2316 contains a buggy "glibc 2.3.2". 2317 2318 The symptom of the bug is that everything crashes on startup, saying: 2319 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2320 2321 Saying Y here changes the default value of the vdso32 boot 2322 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2323 This works around the glibc bug but hurts performance. 2324 2325 If unsure, say N: if you are compiling your own kernel, you 2326 are unlikely to be using a buggy version of glibc. 2327 2328choice 2329 prompt "vsyscall table for legacy applications" 2330 depends on X86_64 2331 default LEGACY_VSYSCALL_XONLY 2332 help 2333 Legacy user code that does not know how to find the vDSO expects 2334 to be able to issue three syscalls by calling fixed addresses in 2335 kernel space. Since this location is not randomized with ASLR, 2336 it can be used to assist security vulnerability exploitation. 2337 2338 This setting can be changed at boot time via the kernel command 2339 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2340 is deprecated and can only be enabled using the kernel command 2341 line. 2342 2343 On a system with recent enough glibc (2.14 or newer) and no 2344 static binaries, you can say None without a performance penalty 2345 to improve security. 2346 2347 If unsure, select "Emulate execution only". 2348 2349 config LEGACY_VSYSCALL_XONLY 2350 bool "Emulate execution only" 2351 help 2352 The kernel traps and emulates calls into the fixed vsyscall 2353 address mapping and does not allow reads. This 2354 configuration is recommended when userspace might use the 2355 legacy vsyscall area but support for legacy binary 2356 instrumentation of legacy code is not needed. It mitigates 2357 certain uses of the vsyscall area as an ASLR-bypassing 2358 buffer. 2359 2360 config LEGACY_VSYSCALL_NONE 2361 bool "None" 2362 help 2363 There will be no vsyscall mapping at all. This will 2364 eliminate any risk of ASLR bypass due to the vsyscall 2365 fixed address mapping. Attempts to use the vsyscalls 2366 will be reported to dmesg, so that either old or 2367 malicious userspace programs can be identified. 2368 2369endchoice 2370 2371config CMDLINE_BOOL 2372 bool "Built-in kernel command line" 2373 help 2374 Allow for specifying boot arguments to the kernel at 2375 build time. On some systems (e.g. embedded ones), it is 2376 necessary or convenient to provide some or all of the 2377 kernel boot arguments with the kernel itself (that is, 2378 to not rely on the boot loader to provide them.) 2379 2380 To compile command line arguments into the kernel, 2381 set this option to 'Y', then fill in the 2382 boot arguments in CONFIG_CMDLINE. 2383 2384 Systems with fully functional boot loaders (i.e. non-embedded) 2385 should leave this option set to 'N'. 2386 2387config CMDLINE 2388 string "Built-in kernel command string" 2389 depends on CMDLINE_BOOL 2390 default "" 2391 help 2392 Enter arguments here that should be compiled into the kernel 2393 image and used at boot time. If the boot loader provides a 2394 command line at boot time, it is appended to this string to 2395 form the full kernel command line, when the system boots. 2396 2397 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2398 change this behavior. 2399 2400 In most cases, the command line (whether built-in or provided 2401 by the boot loader) should specify the device for the root 2402 file system. 2403 2404config CMDLINE_OVERRIDE 2405 bool "Built-in command line overrides boot loader arguments" 2406 depends on CMDLINE_BOOL && CMDLINE != "" 2407 help 2408 Set this option to 'Y' to have the kernel ignore the boot loader 2409 command line, and use ONLY the built-in command line. 2410 2411 This is used to work around broken boot loaders. This should 2412 be set to 'N' under normal conditions. 2413 2414config MODIFY_LDT_SYSCALL 2415 bool "Enable the LDT (local descriptor table)" if EXPERT 2416 default y 2417 help 2418 Linux can allow user programs to install a per-process x86 2419 Local Descriptor Table (LDT) using the modify_ldt(2) system 2420 call. This is required to run 16-bit or segmented code such as 2421 DOSEMU or some Wine programs. It is also used by some very old 2422 threading libraries. 2423 2424 Enabling this feature adds a small amount of overhead to 2425 context switches and increases the low-level kernel attack 2426 surface. Disabling it removes the modify_ldt(2) system call. 2427 2428 Saying 'N' here may make sense for embedded or server kernels. 2429 2430config STRICT_SIGALTSTACK_SIZE 2431 bool "Enforce strict size checking for sigaltstack" 2432 depends on DYNAMIC_SIGFRAME 2433 help 2434 For historical reasons MINSIGSTKSZ is a constant which became 2435 already too small with AVX512 support. Add a mechanism to 2436 enforce strict checking of the sigaltstack size against the 2437 real size of the FPU frame. This option enables the check 2438 by default. It can also be controlled via the kernel command 2439 line option 'strict_sas_size' independent of this config 2440 switch. Enabling it might break existing applications which 2441 allocate a too small sigaltstack but 'work' because they 2442 never get a signal delivered. 2443 2444 Say 'N' unless you want to really enforce this check. 2445 2446source "kernel/livepatch/Kconfig" 2447 2448endmenu 2449 2450config CC_HAS_SLS 2451 def_bool $(cc-option,-mharden-sls=all) 2452 2453config CC_HAS_RETURN_THUNK 2454 def_bool $(cc-option,-mfunction-return=thunk-extern) 2455 2456config CC_HAS_ENTRY_PADDING 2457 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2458 2459config FUNCTION_PADDING_CFI 2460 int 2461 default 59 if FUNCTION_ALIGNMENT_64B 2462 default 27 if FUNCTION_ALIGNMENT_32B 2463 default 11 if FUNCTION_ALIGNMENT_16B 2464 default 3 if FUNCTION_ALIGNMENT_8B 2465 default 0 2466 2467# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2468# except Kconfig can't do arithmetic :/ 2469config FUNCTION_PADDING_BYTES 2470 int 2471 default FUNCTION_PADDING_CFI if CFI_CLANG 2472 default FUNCTION_ALIGNMENT 2473 2474config CALL_PADDING 2475 def_bool n 2476 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2477 select FUNCTION_ALIGNMENT_16B 2478 2479config FINEIBT 2480 def_bool y 2481 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE 2482 select CALL_PADDING 2483 2484config HAVE_CALL_THUNKS 2485 def_bool y 2486 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL 2487 2488config CALL_THUNKS 2489 def_bool n 2490 select CALL_PADDING 2491 2492config PREFIX_SYMBOLS 2493 def_bool y 2494 depends on CALL_PADDING && !CFI_CLANG 2495 2496menuconfig SPECULATION_MITIGATIONS 2497 bool "Mitigations for speculative execution vulnerabilities" 2498 default y 2499 help 2500 Say Y here to enable options which enable mitigations for 2501 speculative execution hardware vulnerabilities. 2502 2503 If you say N, all mitigations will be disabled. You really 2504 should know what you are doing to say so. 2505 2506if SPECULATION_MITIGATIONS 2507 2508config PAGE_TABLE_ISOLATION 2509 bool "Remove the kernel mapping in user mode" 2510 default y 2511 depends on (X86_64 || X86_PAE) 2512 help 2513 This feature reduces the number of hardware side channels by 2514 ensuring that the majority of kernel addresses are not mapped 2515 into userspace. 2516 2517 See Documentation/arch/x86/pti.rst for more details. 2518 2519config RETPOLINE 2520 bool "Avoid speculative indirect branches in kernel" 2521 select OBJTOOL if HAVE_OBJTOOL 2522 default y 2523 help 2524 Compile kernel with the retpoline compiler options to guard against 2525 kernel-to-user data leaks by avoiding speculative indirect 2526 branches. Requires a compiler with -mindirect-branch=thunk-extern 2527 support for full protection. The kernel may run slower. 2528 2529config RETHUNK 2530 bool "Enable return-thunks" 2531 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2532 select OBJTOOL if HAVE_OBJTOOL 2533 default y if X86_64 2534 help 2535 Compile the kernel with the return-thunks compiler option to guard 2536 against kernel-to-user data leaks by avoiding return speculation. 2537 Requires a compiler with -mfunction-return=thunk-extern 2538 support for full protection. The kernel may run slower. 2539 2540config CPU_UNRET_ENTRY 2541 bool "Enable UNRET on kernel entry" 2542 depends on CPU_SUP_AMD && RETHUNK && X86_64 2543 default y 2544 help 2545 Compile the kernel with support for the retbleed=unret mitigation. 2546 2547config CALL_DEPTH_TRACKING 2548 bool "Mitigate RSB underflow with call depth tracking" 2549 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2550 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2551 select CALL_THUNKS 2552 default y 2553 help 2554 Compile the kernel with call depth tracking to mitigate the Intel 2555 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2556 mitigation is off by default and needs to be enabled on the 2557 kernel command line via the retbleed=stuff option. For 2558 non-affected systems the overhead of this option is marginal as 2559 the call depth tracking is using run-time generated call thunks 2560 in a compiler generated padding area and call patching. This 2561 increases text size by ~5%. For non affected systems this space 2562 is unused. On affected SKL systems this results in a significant 2563 performance gain over the IBRS mitigation. 2564 2565config CALL_THUNKS_DEBUG 2566 bool "Enable call thunks and call depth tracking debugging" 2567 depends on CALL_DEPTH_TRACKING 2568 select FUNCTION_ALIGNMENT_32B 2569 default n 2570 help 2571 Enable call/ret counters for imbalance detection and build in 2572 a noisy dmesg about callthunks generation and call patching for 2573 trouble shooting. The debug prints need to be enabled on the 2574 kernel command line with 'debug-callthunks'. 2575 Only enable this when you are debugging call thunks as this 2576 creates a noticeable runtime overhead. If unsure say N. 2577 2578config CPU_IBPB_ENTRY 2579 bool "Enable IBPB on kernel entry" 2580 depends on CPU_SUP_AMD && X86_64 2581 default y 2582 help 2583 Compile the kernel with support for the retbleed=ibpb mitigation. 2584 2585config CPU_IBRS_ENTRY 2586 bool "Enable IBRS on kernel entry" 2587 depends on CPU_SUP_INTEL && X86_64 2588 default y 2589 help 2590 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2591 This mitigates both spectre_v2 and retbleed at great cost to 2592 performance. 2593 2594config SLS 2595 bool "Mitigate Straight-Line-Speculation" 2596 depends on CC_HAS_SLS && X86_64 2597 select OBJTOOL if HAVE_OBJTOOL 2598 default n 2599 help 2600 Compile the kernel with straight-line-speculation options to guard 2601 against straight line speculation. The kernel image might be slightly 2602 larger. 2603 2604endif 2605 2606config ARCH_HAS_ADD_PAGES 2607 def_bool y 2608 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2609 2610config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2611 def_bool y 2612 2613menu "Power management and ACPI options" 2614 2615config ARCH_HIBERNATION_HEADER 2616 def_bool y 2617 depends on HIBERNATION 2618 2619source "kernel/power/Kconfig" 2620 2621source "drivers/acpi/Kconfig" 2622 2623config X86_APM_BOOT 2624 def_bool y 2625 depends on APM 2626 2627menuconfig APM 2628 tristate "APM (Advanced Power Management) BIOS support" 2629 depends on X86_32 && PM_SLEEP 2630 help 2631 APM is a BIOS specification for saving power using several different 2632 techniques. This is mostly useful for battery powered laptops with 2633 APM compliant BIOSes. If you say Y here, the system time will be 2634 reset after a RESUME operation, the /proc/apm device will provide 2635 battery status information, and user-space programs will receive 2636 notification of APM "events" (e.g. battery status change). 2637 2638 If you select "Y" here, you can disable actual use of the APM 2639 BIOS by passing the "apm=off" option to the kernel at boot time. 2640 2641 Note that the APM support is almost completely disabled for 2642 machines with more than one CPU. 2643 2644 In order to use APM, you will need supporting software. For location 2645 and more information, read <file:Documentation/power/apm-acpi.rst> 2646 and the Battery Powered Linux mini-HOWTO, available from 2647 <http://www.tldp.org/docs.html#howto>. 2648 2649 This driver does not spin down disk drives (see the hdparm(8) 2650 manpage ("man 8 hdparm") for that), and it doesn't turn off 2651 VESA-compliant "green" monitors. 2652 2653 This driver does not support the TI 4000M TravelMate and the ACER 2654 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2655 desktop machines also don't have compliant BIOSes, and this driver 2656 may cause those machines to panic during the boot phase. 2657 2658 Generally, if you don't have a battery in your machine, there isn't 2659 much point in using this driver and you should say N. If you get 2660 random kernel OOPSes or reboots that don't seem to be related to 2661 anything, try disabling/enabling this option (or disabling/enabling 2662 APM in your BIOS). 2663 2664 Some other things you should try when experiencing seemingly random, 2665 "weird" problems: 2666 2667 1) make sure that you have enough swap space and that it is 2668 enabled. 2669 2) pass the "idle=poll" option to the kernel 2670 3) switch on floating point emulation in the kernel and pass 2671 the "no387" option to the kernel 2672 4) pass the "floppy=nodma" option to the kernel 2673 5) pass the "mem=4M" option to the kernel (thereby disabling 2674 all but the first 4 MB of RAM) 2675 6) make sure that the CPU is not over clocked. 2676 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2677 8) disable the cache from your BIOS settings 2678 9) install a fan for the video card or exchange video RAM 2679 10) install a better fan for the CPU 2680 11) exchange RAM chips 2681 12) exchange the motherboard. 2682 2683 To compile this driver as a module, choose M here: the 2684 module will be called apm. 2685 2686if APM 2687 2688config APM_IGNORE_USER_SUSPEND 2689 bool "Ignore USER SUSPEND" 2690 help 2691 This option will ignore USER SUSPEND requests. On machines with a 2692 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2693 series notebooks, it is necessary to say Y because of a BIOS bug. 2694 2695config APM_DO_ENABLE 2696 bool "Enable PM at boot time" 2697 help 2698 Enable APM features at boot time. From page 36 of the APM BIOS 2699 specification: "When disabled, the APM BIOS does not automatically 2700 power manage devices, enter the Standby State, enter the Suspend 2701 State, or take power saving steps in response to CPU Idle calls." 2702 This driver will make CPU Idle calls when Linux is idle (unless this 2703 feature is turned off -- see "Do CPU IDLE calls", below). This 2704 should always save battery power, but more complicated APM features 2705 will be dependent on your BIOS implementation. You may need to turn 2706 this option off if your computer hangs at boot time when using APM 2707 support, or if it beeps continuously instead of suspending. Turn 2708 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2709 T400CDT. This is off by default since most machines do fine without 2710 this feature. 2711 2712config APM_CPU_IDLE 2713 depends on CPU_IDLE 2714 bool "Make CPU Idle calls when idle" 2715 help 2716 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2717 On some machines, this can activate improved power savings, such as 2718 a slowed CPU clock rate, when the machine is idle. These idle calls 2719 are made after the idle loop has run for some length of time (e.g., 2720 333 mS). On some machines, this will cause a hang at boot time or 2721 whenever the CPU becomes idle. (On machines with more than one CPU, 2722 this option does nothing.) 2723 2724config APM_DISPLAY_BLANK 2725 bool "Enable console blanking using APM" 2726 help 2727 Enable console blanking using the APM. Some laptops can use this to 2728 turn off the LCD backlight when the screen blanker of the Linux 2729 virtual console blanks the screen. Note that this is only used by 2730 the virtual console screen blanker, and won't turn off the backlight 2731 when using the X Window system. This also doesn't have anything to 2732 do with your VESA-compliant power-saving monitor. Further, this 2733 option doesn't work for all laptops -- it might not turn off your 2734 backlight at all, or it might print a lot of errors to the console, 2735 especially if you are using gpm. 2736 2737config APM_ALLOW_INTS 2738 bool "Allow interrupts during APM BIOS calls" 2739 help 2740 Normally we disable external interrupts while we are making calls to 2741 the APM BIOS as a measure to lessen the effects of a badly behaving 2742 BIOS implementation. The BIOS should reenable interrupts if it 2743 needs to. Unfortunately, some BIOSes do not -- especially those in 2744 many of the newer IBM Thinkpads. If you experience hangs when you 2745 suspend, try setting this to Y. Otherwise, say N. 2746 2747endif # APM 2748 2749source "drivers/cpufreq/Kconfig" 2750 2751source "drivers/cpuidle/Kconfig" 2752 2753source "drivers/idle/Kconfig" 2754 2755endmenu 2756 2757menu "Bus options (PCI etc.)" 2758 2759choice 2760 prompt "PCI access mode" 2761 depends on X86_32 && PCI 2762 default PCI_GOANY 2763 help 2764 On PCI systems, the BIOS can be used to detect the PCI devices and 2765 determine their configuration. However, some old PCI motherboards 2766 have BIOS bugs and may crash if this is done. Also, some embedded 2767 PCI-based systems don't have any BIOS at all. Linux can also try to 2768 detect the PCI hardware directly without using the BIOS. 2769 2770 With this option, you can specify how Linux should detect the 2771 PCI devices. If you choose "BIOS", the BIOS will be used, 2772 if you choose "Direct", the BIOS won't be used, and if you 2773 choose "MMConfig", then PCI Express MMCONFIG will be used. 2774 If you choose "Any", the kernel will try MMCONFIG, then the 2775 direct access method and falls back to the BIOS if that doesn't 2776 work. If unsure, go with the default, which is "Any". 2777 2778config PCI_GOBIOS 2779 bool "BIOS" 2780 2781config PCI_GOMMCONFIG 2782 bool "MMConfig" 2783 2784config PCI_GODIRECT 2785 bool "Direct" 2786 2787config PCI_GOOLPC 2788 bool "OLPC XO-1" 2789 depends on OLPC 2790 2791config PCI_GOANY 2792 bool "Any" 2793 2794endchoice 2795 2796config PCI_BIOS 2797 def_bool y 2798 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2799 2800# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2801config PCI_DIRECT 2802 def_bool y 2803 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2804 2805config PCI_MMCONFIG 2806 bool "Support mmconfig PCI config space access" if X86_64 2807 default y 2808 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2809 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2810 2811config PCI_OLPC 2812 def_bool y 2813 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2814 2815config PCI_XEN 2816 def_bool y 2817 depends on PCI && XEN 2818 2819config MMCONF_FAM10H 2820 def_bool y 2821 depends on X86_64 && PCI_MMCONFIG && ACPI 2822 2823config PCI_CNB20LE_QUIRK 2824 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2825 depends on PCI 2826 help 2827 Read the PCI windows out of the CNB20LE host bridge. This allows 2828 PCI hotplug to work on systems with the CNB20LE chipset which do 2829 not have ACPI. 2830 2831 There's no public spec for this chipset, and this functionality 2832 is known to be incomplete. 2833 2834 You should say N unless you know you need this. 2835 2836config ISA_BUS 2837 bool "ISA bus support on modern systems" if EXPERT 2838 help 2839 Expose ISA bus device drivers and options available for selection and 2840 configuration. Enable this option if your target machine has an ISA 2841 bus. ISA is an older system, displaced by PCI and newer bus 2842 architectures -- if your target machine is modern, it probably does 2843 not have an ISA bus. 2844 2845 If unsure, say N. 2846 2847# x86_64 have no ISA slots, but can have ISA-style DMA. 2848config ISA_DMA_API 2849 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2850 default y 2851 help 2852 Enables ISA-style DMA support for devices requiring such controllers. 2853 If unsure, say Y. 2854 2855if X86_32 2856 2857config ISA 2858 bool "ISA support" 2859 help 2860 Find out whether you have ISA slots on your motherboard. ISA is the 2861 name of a bus system, i.e. the way the CPU talks to the other stuff 2862 inside your box. Other bus systems are PCI, EISA, MicroChannel 2863 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2864 newer boards don't support it. If you have ISA, say Y, otherwise N. 2865 2866config SCx200 2867 tristate "NatSemi SCx200 support" 2868 help 2869 This provides basic support for National Semiconductor's 2870 (now AMD's) Geode processors. The driver probes for the 2871 PCI-IDs of several on-chip devices, so its a good dependency 2872 for other scx200_* drivers. 2873 2874 If compiled as a module, the driver is named scx200. 2875 2876config SCx200HR_TIMER 2877 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2878 depends on SCx200 2879 default y 2880 help 2881 This driver provides a clocksource built upon the on-chip 2882 27MHz high-resolution timer. Its also a workaround for 2883 NSC Geode SC-1100's buggy TSC, which loses time when the 2884 processor goes idle (as is done by the scheduler). The 2885 other workaround is idle=poll boot option. 2886 2887config OLPC 2888 bool "One Laptop Per Child support" 2889 depends on !X86_PAE 2890 select GPIOLIB 2891 select OF 2892 select OF_PROMTREE 2893 select IRQ_DOMAIN 2894 select OLPC_EC 2895 help 2896 Add support for detecting the unique features of the OLPC 2897 XO hardware. 2898 2899config OLPC_XO1_PM 2900 bool "OLPC XO-1 Power Management" 2901 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2902 help 2903 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2904 2905config OLPC_XO1_RTC 2906 bool "OLPC XO-1 Real Time Clock" 2907 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2908 help 2909 Add support for the XO-1 real time clock, which can be used as a 2910 programmable wakeup source. 2911 2912config OLPC_XO1_SCI 2913 bool "OLPC XO-1 SCI extras" 2914 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2915 depends on INPUT=y 2916 select POWER_SUPPLY 2917 help 2918 Add support for SCI-based features of the OLPC XO-1 laptop: 2919 - EC-driven system wakeups 2920 - Power button 2921 - Ebook switch 2922 - Lid switch 2923 - AC adapter status updates 2924 - Battery status updates 2925 2926config OLPC_XO15_SCI 2927 bool "OLPC XO-1.5 SCI extras" 2928 depends on OLPC && ACPI 2929 select POWER_SUPPLY 2930 help 2931 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2932 - EC-driven system wakeups 2933 - AC adapter status updates 2934 - Battery status updates 2935 2936config ALIX 2937 bool "PCEngines ALIX System Support (LED setup)" 2938 select GPIOLIB 2939 help 2940 This option enables system support for the PCEngines ALIX. 2941 At present this just sets up LEDs for GPIO control on 2942 ALIX2/3/6 boards. However, other system specific setup should 2943 get added here. 2944 2945 Note: You must still enable the drivers for GPIO and LED support 2946 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2947 2948 Note: You have to set alix.force=1 for boards with Award BIOS. 2949 2950config NET5501 2951 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2952 select GPIOLIB 2953 help 2954 This option enables system support for the Soekris Engineering net5501. 2955 2956config GEOS 2957 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2958 select GPIOLIB 2959 depends on DMI 2960 help 2961 This option enables system support for the Traverse Technologies GEOS. 2962 2963config TS5500 2964 bool "Technologic Systems TS-5500 platform support" 2965 depends on MELAN 2966 select CHECK_SIGNATURE 2967 select NEW_LEDS 2968 select LEDS_CLASS 2969 help 2970 This option enables system support for the Technologic Systems TS-5500. 2971 2972endif # X86_32 2973 2974config AMD_NB 2975 def_bool y 2976 depends on CPU_SUP_AMD && PCI 2977 2978endmenu 2979 2980menu "Binary Emulations" 2981 2982config IA32_EMULATION 2983 bool "IA32 Emulation" 2984 depends on X86_64 2985 select ARCH_WANT_OLD_COMPAT_IPC 2986 select BINFMT_ELF 2987 select COMPAT_OLD_SIGACTION 2988 help 2989 Include code to run legacy 32-bit programs under a 2990 64-bit kernel. You should likely turn this on, unless you're 2991 100% sure that you don't have any 32-bit programs left. 2992 2993config X86_X32_ABI 2994 bool "x32 ABI for 64-bit mode" 2995 depends on X86_64 2996 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2997 # compressed debug sections to x86_x32 properly: 2998 # https://github.com/ClangBuiltLinux/linux/issues/514 2999 # https://github.com/ClangBuiltLinux/linux/issues/1141 3000 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3001 help 3002 Include code to run binaries for the x32 native 32-bit ABI 3003 for 64-bit processors. An x32 process gets access to the 3004 full 64-bit register file and wide data path while leaving 3005 pointers at 32 bits for smaller memory footprint. 3006 3007config COMPAT_32 3008 def_bool y 3009 depends on IA32_EMULATION || X86_32 3010 select HAVE_UID16 3011 select OLD_SIGSUSPEND3 3012 3013config COMPAT 3014 def_bool y 3015 depends on IA32_EMULATION || X86_X32_ABI 3016 3017config COMPAT_FOR_U64_ALIGNMENT 3018 def_bool y 3019 depends on COMPAT 3020 3021endmenu 3022 3023config HAVE_ATOMIC_IOMAP 3024 def_bool y 3025 depends on X86_32 3026 3027source "arch/x86/kvm/Kconfig" 3028 3029source "arch/x86/Kconfig.assembler" 3030