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