1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select HAVE_ARCH_SOFT_DIRTY 32 select MODULES_USE_ELF_RELA 33 select NEED_DMA_MAP_STATE 34 select SWIOTLB 35 select ARCH_HAS_ELFCORE_COMPAT 36 select ZONE_DMA32 37 38config FORCE_DYNAMIC_FTRACE 39 def_bool y 40 depends on X86_32 41 depends on FUNCTION_TRACER 42 select DYNAMIC_FTRACE 43 help 44 We keep the static function tracing (!DYNAMIC_FTRACE) around 45 in order to test the non static function tracing in the 46 generic code, as other architectures still use it. But we 47 only need to keep it around for x86_64. No need to keep it 48 for x86_32. For x86_32, force DYNAMIC_FTRACE. 49# 50# Arch settings 51# 52# ( Note that options that are marked 'if X86_64' could in principle be 53# ported to 32-bit as well. ) 54# 55config X86 56 def_bool y 57 # 58 # Note: keep this list sorted alphabetically 59 # 60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 62 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 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_CPU_PASID if IOMMU_SVA 76 select ARCH_HAS_CURRENT_STACK_POINTER 77 select ARCH_HAS_DEBUG_VIRTUAL 78 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 79 select ARCH_HAS_DEVMEM_IS_ALLOWED 80 select ARCH_HAS_EARLY_DEBUG if KGDB 81 select ARCH_HAS_ELF_RANDOMIZE 82 select ARCH_HAS_FAST_MULTIPLIER 83 select ARCH_HAS_FORTIFY_SOURCE 84 select ARCH_HAS_GCOV_PROFILE_ALL 85 select ARCH_HAS_KCOV if X86_64 86 select ARCH_HAS_MEM_ENCRYPT 87 select ARCH_HAS_MEMBARRIER_SYNC_CORE 88 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 89 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 90 select ARCH_HAS_PMEM_API if X86_64 91 select ARCH_HAS_PTE_DEVMAP if X86_64 92 select ARCH_HAS_PTE_SPECIAL 93 select ARCH_HAS_HW_PTE_YOUNG 94 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 95 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 96 select ARCH_HAS_COPY_MC if X86_64 97 select ARCH_HAS_SET_MEMORY 98 select ARCH_HAS_SET_DIRECT_MAP 99 select ARCH_HAS_STRICT_KERNEL_RWX 100 select ARCH_HAS_STRICT_MODULE_RWX 101 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 102 select ARCH_HAS_SYSCALL_WRAPPER 103 select ARCH_HAS_UBSAN_SANITIZE_ALL 104 select ARCH_HAS_DEBUG_WX 105 select ARCH_HAS_ZONE_DMA_SET if EXPERT 106 select ARCH_HAVE_NMI_SAFE_CMPXCHG 107 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 108 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 109 select ARCH_MIGHT_HAVE_PC_PARPORT 110 select ARCH_MIGHT_HAVE_PC_SERIO 111 select ARCH_STACKWALK 112 select ARCH_SUPPORTS_ACPI 113 select ARCH_SUPPORTS_ATOMIC_RMW 114 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 115 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 116 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 117 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 118 select ARCH_SUPPORTS_CFI_CLANG if X86_64 119 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 120 select ARCH_SUPPORTS_LTO_CLANG 121 select ARCH_SUPPORTS_LTO_CLANG_THIN 122 select ARCH_USE_BUILTIN_BSWAP 123 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64 124 select ARCH_USE_MEMTEST 125 select ARCH_USE_QUEUED_RWLOCKS 126 select ARCH_USE_QUEUED_SPINLOCKS 127 select ARCH_USE_SYM_ANNOTATIONS 128 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 129 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 130 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 131 select ARCH_WANTS_NO_INSTR 132 select ARCH_WANT_GENERAL_HUGETLB 133 select ARCH_WANT_HUGE_PMD_SHARE 134 select ARCH_WANT_LD_ORPHAN_WARN 135 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 136 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 137 select ARCH_WANTS_THP_SWAP if X86_64 138 select ARCH_HAS_PARANOID_L1D_FLUSH 139 select BUILDTIME_TABLE_SORT 140 select CLKEVT_I8253 141 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 142 select CLOCKSOURCE_WATCHDOG 143 # Word-size accesses may read uninitialized data past the trailing \0 144 # in strings and cause false KMSAN reports. 145 select DCACHE_WORD_ACCESS if !KMSAN 146 select DYNAMIC_SIGFRAME 147 select EDAC_ATOMIC_SCRUB 148 select EDAC_SUPPORT 149 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 150 select GENERIC_CLOCKEVENTS_MIN_ADJUST 151 select GENERIC_CMOS_UPDATE 152 select GENERIC_CPU_AUTOPROBE 153 select GENERIC_CPU_DEVICES 154 select GENERIC_CPU_VULNERABILITIES 155 select GENERIC_EARLY_IOREMAP 156 select GENERIC_ENTRY 157 select GENERIC_IOMAP 158 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 159 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 160 select GENERIC_IRQ_MIGRATION if SMP 161 select GENERIC_IRQ_PROBE 162 select GENERIC_IRQ_RESERVATION_MODE 163 select GENERIC_IRQ_SHOW 164 select GENERIC_PENDING_IRQ if SMP 165 select GENERIC_PTDUMP 166 select GENERIC_SMP_IDLE_THREAD 167 select GENERIC_TIME_VSYSCALL 168 select GENERIC_GETTIMEOFDAY 169 select GENERIC_VDSO_TIME_NS 170 select GUP_GET_PXX_LOW_HIGH if X86_PAE 171 select HARDIRQS_SW_RESEND 172 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 173 select HAS_IOPORT 174 select HAVE_ACPI_APEI if ACPI 175 select HAVE_ACPI_APEI_NMI if ACPI 176 select HAVE_ALIGNED_STRUCT_PAGE 177 select HAVE_ARCH_AUDITSYSCALL 178 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 179 select HAVE_ARCH_HUGE_VMALLOC if X86_64 180 select HAVE_ARCH_JUMP_LABEL 181 select HAVE_ARCH_JUMP_LABEL_RELATIVE 182 select HAVE_ARCH_KASAN if X86_64 183 select HAVE_ARCH_KASAN_VMALLOC if X86_64 184 select HAVE_ARCH_KFENCE 185 select HAVE_ARCH_KMSAN if X86_64 186 select HAVE_ARCH_KGDB 187 select HAVE_ARCH_MMAP_RND_BITS if MMU 188 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 189 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 190 select HAVE_ARCH_PREL32_RELOCATIONS 191 select HAVE_ARCH_SECCOMP_FILTER 192 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 193 select HAVE_ARCH_STACKLEAK 194 select HAVE_ARCH_TRACEHOOK 195 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 196 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 197 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 198 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 199 select HAVE_ARCH_VMAP_STACK if X86_64 200 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 201 select HAVE_ARCH_WITHIN_STACK_FRAMES 202 select HAVE_ASM_MODVERSIONS 203 select HAVE_CMPXCHG_DOUBLE 204 select HAVE_CMPXCHG_LOCAL 205 select HAVE_CONTEXT_TRACKING_USER if X86_64 206 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 207 select HAVE_C_RECORDMCOUNT 208 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 209 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 210 select HAVE_BUILDTIME_MCOUNT_SORT 211 select HAVE_DEBUG_KMEMLEAK 212 select HAVE_DMA_CONTIGUOUS 213 select HAVE_DYNAMIC_FTRACE 214 select HAVE_DYNAMIC_FTRACE_WITH_REGS 215 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 216 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 217 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 218 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 219 select HAVE_EBPF_JIT 220 select HAVE_EFFICIENT_UNALIGNED_ACCESS 221 select HAVE_EISA 222 select HAVE_EXIT_THREAD 223 select HAVE_FAST_GUP 224 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 225 select HAVE_FTRACE_MCOUNT_RECORD 226 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 227 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 228 select HAVE_FUNCTION_TRACER 229 select HAVE_GCC_PLUGINS 230 select HAVE_HW_BREAKPOINT 231 select HAVE_IOREMAP_PROT 232 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 233 select HAVE_IRQ_TIME_ACCOUNTING 234 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 235 select HAVE_KERNEL_BZIP2 236 select HAVE_KERNEL_GZIP 237 select HAVE_KERNEL_LZ4 238 select HAVE_KERNEL_LZMA 239 select HAVE_KERNEL_LZO 240 select HAVE_KERNEL_XZ 241 select HAVE_KERNEL_ZSTD 242 select HAVE_KPROBES 243 select HAVE_KPROBES_ON_FTRACE 244 select HAVE_FUNCTION_ERROR_INJECTION 245 select HAVE_KRETPROBES 246 select HAVE_RETHOOK 247 select HAVE_KVM 248 select HAVE_LIVEPATCH if X86_64 249 select HAVE_MIXED_BREAKPOINTS_REGS 250 select HAVE_MOD_ARCH_SPECIFIC 251 select HAVE_MOVE_PMD 252 select HAVE_MOVE_PUD 253 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 254 select HAVE_NMI 255 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 256 select HAVE_OBJTOOL if X86_64 257 select HAVE_OPTPROBES 258 select HAVE_PCSPKR_PLATFORM 259 select HAVE_PERF_EVENTS 260 select HAVE_PERF_EVENTS_NMI 261 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 262 select HAVE_PCI 263 select HAVE_PERF_REGS 264 select HAVE_PERF_USER_STACK_DUMP 265 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 266 select MMU_GATHER_MERGE_VMAS 267 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 268 select HAVE_REGS_AND_STACK_ACCESS_API 269 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 270 select HAVE_FUNCTION_ARG_ACCESS_API 271 select HAVE_SETUP_PER_CPU_AREA 272 select HAVE_SOFTIRQ_ON_OWN_STACK 273 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 274 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 275 select HAVE_STATIC_CALL 276 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 277 select HAVE_PREEMPT_DYNAMIC_CALL 278 select HAVE_RSEQ 279 select HAVE_RUST if X86_64 280 select HAVE_SYSCALL_TRACEPOINTS 281 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 282 select HAVE_UNSTABLE_SCHED_CLOCK 283 select HAVE_USER_RETURN_NOTIFIER 284 select HAVE_GENERIC_VDSO 285 select HOTPLUG_PARALLEL if SMP && X86_64 286 select HOTPLUG_SMT if SMP 287 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 288 select IRQ_FORCED_THREADING 289 select LOCK_MM_AND_FIND_VMA 290 select NEED_PER_CPU_EMBED_FIRST_CHUNK 291 select NEED_PER_CPU_PAGE_FIRST_CHUNK 292 select NEED_SG_DMA_LENGTH 293 select PCI_DOMAINS if PCI 294 select PCI_LOCKLESS_CONFIG if PCI 295 select PERF_EVENTS 296 select RTC_LIB 297 select RTC_MC146818_LIB 298 select SPARSE_IRQ 299 select SYSCTL_EXCEPTION_TRACE 300 select THREAD_INFO_IN_TASK 301 select TRACE_IRQFLAGS_SUPPORT 302 select TRACE_IRQFLAGS_NMI_SUPPORT 303 select USER_STACKTRACE_SUPPORT 304 select HAVE_ARCH_KCSAN if X86_64 305 select PROC_PID_ARCH_STATUS if PROC_FS 306 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 307 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 308 select FUNCTION_ALIGNMENT_4B 309 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 310 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 311 312config INSTRUCTION_DECODER 313 def_bool y 314 depends on KPROBES || PERF_EVENTS || UPROBES 315 316config OUTPUT_FORMAT 317 string 318 default "elf32-i386" if X86_32 319 default "elf64-x86-64" if X86_64 320 321config LOCKDEP_SUPPORT 322 def_bool y 323 324config STACKTRACE_SUPPORT 325 def_bool y 326 327config MMU 328 def_bool y 329 330config ARCH_MMAP_RND_BITS_MIN 331 default 28 if 64BIT 332 default 8 333 334config ARCH_MMAP_RND_BITS_MAX 335 default 32 if 64BIT 336 default 16 337 338config ARCH_MMAP_RND_COMPAT_BITS_MIN 339 default 8 340 341config ARCH_MMAP_RND_COMPAT_BITS_MAX 342 default 16 343 344config SBUS 345 bool 346 347config GENERIC_ISA_DMA 348 def_bool y 349 depends on ISA_DMA_API 350 351config GENERIC_CSUM 352 bool 353 default y if KMSAN || KASAN 354 355config GENERIC_BUG 356 def_bool y 357 depends on BUG 358 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 359 360config GENERIC_BUG_RELATIVE_POINTERS 361 bool 362 363config ARCH_MAY_HAVE_PC_FDC 364 def_bool y 365 depends on ISA_DMA_API 366 367config GENERIC_CALIBRATE_DELAY 368 def_bool y 369 370config ARCH_HAS_CPU_RELAX 371 def_bool y 372 373config ARCH_HIBERNATION_POSSIBLE 374 def_bool y 375 376config ARCH_SUSPEND_POSSIBLE 377 def_bool y 378 379config AUDIT_ARCH 380 def_bool y if X86_64 381 382config KASAN_SHADOW_OFFSET 383 hex 384 depends on KASAN 385 default 0xdffffc0000000000 386 387config HAVE_INTEL_TXT 388 def_bool y 389 depends on INTEL_IOMMU && ACPI 390 391config X86_64_SMP 392 def_bool y 393 depends on X86_64 && SMP 394 395config ARCH_SUPPORTS_UPROBES 396 def_bool y 397 398config FIX_EARLYCON_MEM 399 def_bool y 400 401config DYNAMIC_PHYSICAL_MASK 402 bool 403 404config PGTABLE_LEVELS 405 int 406 default 5 if X86_5LEVEL 407 default 4 if X86_64 408 default 3 if X86_PAE 409 default 2 410 411config CC_HAS_SANE_STACKPROTECTOR 412 bool 413 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 414 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 415 help 416 We have to make sure stack protector is unconditionally disabled if 417 the compiler produces broken code or if it does not let us control 418 the segment on 32-bit kernels. 419 420menu "Processor type and features" 421 422config SMP 423 bool "Symmetric multi-processing support" 424 help 425 This enables support for systems with more than one CPU. If you have 426 a system with only one CPU, say N. If you have a system with more 427 than one CPU, say Y. 428 429 If you say N here, the kernel will run on uni- and multiprocessor 430 machines, but will use only one CPU of a multiprocessor machine. If 431 you say Y here, the kernel will run on many, but not all, 432 uniprocessor machines. On a uniprocessor machine, the kernel 433 will run faster if you say N here. 434 435 Note that if you say Y here and choose architecture "586" or 436 "Pentium" under "Processor family", the kernel will not work on 486 437 architectures. Similarly, multiprocessor kernels for the "PPro" 438 architecture may not work on all Pentium based boards. 439 440 People using multiprocessor machines who say Y here should also say 441 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 442 Management" code will be disabled if you say Y here. 443 444 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 445 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 446 <http://www.tldp.org/docs.html#howto>. 447 448 If you don't know what to do here, say N. 449 450config X86_X2APIC 451 bool "Support x2apic" 452 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 453 help 454 This enables x2apic support on CPUs that have this feature. 455 456 This allows 32-bit apic IDs (so it can support very large systems), 457 and accesses the local apic via MSRs not via mmio. 458 459 Some Intel systems circa 2022 and later are locked into x2APIC mode 460 and can not fall back to the legacy APIC modes if SGX or TDX are 461 enabled in the BIOS. They will boot with very reduced functionality 462 without enabling this option. 463 464 If you don't know what to do here, say N. 465 466config X86_MPPARSE 467 bool "Enable MPS table" if ACPI 468 default y 469 depends on X86_LOCAL_APIC 470 help 471 For old smp systems that do not have proper acpi support. Newer systems 472 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 473 474config GOLDFISH 475 def_bool y 476 depends on X86_GOLDFISH 477 478config X86_CPU_RESCTRL 479 bool "x86 CPU resource control support" 480 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 481 select KERNFS 482 select PROC_CPU_RESCTRL if PROC_FS 483 help 484 Enable x86 CPU resource control support. 485 486 Provide support for the allocation and monitoring of system resources 487 usage by the CPU. 488 489 Intel calls this Intel Resource Director Technology 490 (Intel(R) RDT). More information about RDT can be found in the 491 Intel x86 Architecture Software Developer Manual. 492 493 AMD calls this AMD Platform Quality of Service (AMD QoS). 494 More information about AMD QoS can be found in the AMD64 Technology 495 Platform Quality of Service Extensions manual. 496 497 Say N if unsure. 498 499if X86_32 500config X86_BIGSMP 501 bool "Support for big SMP systems with more than 8 CPUs" 502 depends on SMP 503 help 504 This option is needed for the systems that have more than 8 CPUs. 505 506config X86_EXTENDED_PLATFORM 507 bool "Support for extended (non-PC) x86 platforms" 508 default y 509 help 510 If you disable this option then the kernel will only support 511 standard PC platforms. (which covers the vast majority of 512 systems out there.) 513 514 If you enable this option then you'll be able to select support 515 for the following (non-PC) 32 bit x86 platforms: 516 Goldfish (Android emulator) 517 AMD Elan 518 RDC R-321x SoC 519 SGI 320/540 (Visual Workstation) 520 STA2X11-based (e.g. Northville) 521 Moorestown MID devices 522 523 If you have one of these systems, or if you want to build a 524 generic distribution kernel, say Y here - otherwise say N. 525endif # X86_32 526 527if X86_64 528config X86_EXTENDED_PLATFORM 529 bool "Support for extended (non-PC) x86 platforms" 530 default y 531 help 532 If you disable this option then the kernel will only support 533 standard PC platforms. (which covers the vast majority of 534 systems out there.) 535 536 If you enable this option then you'll be able to select support 537 for the following (non-PC) 64 bit x86 platforms: 538 Numascale NumaChip 539 ScaleMP vSMP 540 SGI Ultraviolet 541 542 If you have one of these systems, or if you want to build a 543 generic distribution kernel, say Y here - otherwise say N. 544endif # X86_64 545# This is an alphabetically sorted list of 64 bit extended platforms 546# Please maintain the alphabetic order if and when there are additions 547config X86_NUMACHIP 548 bool "Numascale NumaChip" 549 depends on X86_64 550 depends on X86_EXTENDED_PLATFORM 551 depends on NUMA 552 depends on SMP 553 depends on X86_X2APIC 554 depends on PCI_MMCONFIG 555 help 556 Adds support for Numascale NumaChip large-SMP systems. Needed to 557 enable more than ~168 cores. 558 If you don't have one of these, you should say N here. 559 560config X86_VSMP 561 bool "ScaleMP vSMP" 562 select HYPERVISOR_GUEST 563 select PARAVIRT 564 depends on X86_64 && PCI 565 depends on X86_EXTENDED_PLATFORM 566 depends on SMP 567 help 568 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 569 supposed to run on these EM64T-based machines. Only choose this option 570 if you have one of these machines. 571 572config X86_UV 573 bool "SGI Ultraviolet" 574 depends on X86_64 575 depends on X86_EXTENDED_PLATFORM 576 depends on NUMA 577 depends on EFI 578 depends on KEXEC_CORE 579 depends on X86_X2APIC 580 depends on PCI 581 help 582 This option is needed in order to support SGI Ultraviolet systems. 583 If you don't have one of these, you should say N here. 584 585# Following is an alphabetically sorted list of 32 bit extended platforms 586# Please maintain the alphabetic order if and when there are additions 587 588config X86_GOLDFISH 589 bool "Goldfish (Virtual Platform)" 590 depends on X86_EXTENDED_PLATFORM 591 help 592 Enable support for the Goldfish virtual platform used primarily 593 for Android development. Unless you are building for the Android 594 Goldfish emulator say N here. 595 596config X86_INTEL_CE 597 bool "CE4100 TV platform" 598 depends on PCI 599 depends on PCI_GODIRECT 600 depends on X86_IO_APIC 601 depends on X86_32 602 depends on X86_EXTENDED_PLATFORM 603 select X86_REBOOTFIXUPS 604 select OF 605 select OF_EARLY_FLATTREE 606 help 607 Select for the Intel CE media processor (CE4100) SOC. 608 This option compiles in support for the CE4100 SOC for settop 609 boxes and media devices. 610 611config X86_INTEL_MID 612 bool "Intel MID platform support" 613 depends on X86_EXTENDED_PLATFORM 614 depends on X86_PLATFORM_DEVICES 615 depends on PCI 616 depends on X86_64 || (PCI_GOANY && X86_32) 617 depends on X86_IO_APIC 618 select I2C 619 select DW_APB_TIMER 620 select INTEL_SCU_PCI 621 help 622 Select to build a kernel capable of supporting Intel MID (Mobile 623 Internet Device) platform systems which do not have the PCI legacy 624 interfaces. If you are building for a PC class system say N here. 625 626 Intel MID platforms are based on an Intel processor and chipset which 627 consume less power than most of the x86 derivatives. 628 629config X86_INTEL_QUARK 630 bool "Intel Quark platform support" 631 depends on X86_32 632 depends on X86_EXTENDED_PLATFORM 633 depends on X86_PLATFORM_DEVICES 634 depends on X86_TSC 635 depends on PCI 636 depends on PCI_GOANY 637 depends on X86_IO_APIC 638 select IOSF_MBI 639 select INTEL_IMR 640 select COMMON_CLK 641 help 642 Select to include support for Quark X1000 SoC. 643 Say Y here if you have a Quark based system such as the Arduino 644 compatible Intel Galileo. 645 646config X86_INTEL_LPSS 647 bool "Intel Low Power Subsystem Support" 648 depends on X86 && ACPI && PCI 649 select COMMON_CLK 650 select PINCTRL 651 select IOSF_MBI 652 help 653 Select to build support for Intel Low Power Subsystem such as 654 found on Intel Lynxpoint PCH. Selecting this option enables 655 things like clock tree (common clock framework) and pincontrol 656 which are needed by the LPSS peripheral drivers. 657 658config X86_AMD_PLATFORM_DEVICE 659 bool "AMD ACPI2Platform devices support" 660 depends on ACPI 661 select COMMON_CLK 662 select PINCTRL 663 help 664 Select to interpret AMD specific ACPI device to platform device 665 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 666 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 667 implemented under PINCTRL subsystem. 668 669config IOSF_MBI 670 tristate "Intel SoC IOSF Sideband support for SoC platforms" 671 depends on PCI 672 help 673 This option enables sideband register access support for Intel SoC 674 platforms. On these platforms the IOSF sideband is used in lieu of 675 MSR's for some register accesses, mostly but not limited to thermal 676 and power. Drivers may query the availability of this device to 677 determine if they need the sideband in order to work on these 678 platforms. The sideband is available on the following SoC products. 679 This list is not meant to be exclusive. 680 - BayTrail 681 - Braswell 682 - Quark 683 684 You should say Y if you are running a kernel on one of these SoC's. 685 686config IOSF_MBI_DEBUG 687 bool "Enable IOSF sideband access through debugfs" 688 depends on IOSF_MBI && DEBUG_FS 689 help 690 Select this option to expose the IOSF sideband access registers (MCR, 691 MDR, MCRX) through debugfs to write and read register information from 692 different units on the SoC. This is most useful for obtaining device 693 state information for debug and analysis. As this is a general access 694 mechanism, users of this option would have specific knowledge of the 695 device they want to access. 696 697 If you don't require the option or are in doubt, say N. 698 699config X86_RDC321X 700 bool "RDC R-321x SoC" 701 depends on X86_32 702 depends on X86_EXTENDED_PLATFORM 703 select M486 704 select X86_REBOOTFIXUPS 705 help 706 This option is needed for RDC R-321x system-on-chip, also known 707 as R-8610-(G). 708 If you don't have one of these chips, you should say N here. 709 710config X86_32_NON_STANDARD 711 bool "Support non-standard 32-bit SMP architectures" 712 depends on X86_32 && SMP 713 depends on X86_EXTENDED_PLATFORM 714 help 715 This option compiles in the bigsmp and STA2X11 default 716 subarchitectures. It is intended for a generic binary 717 kernel. If you select them all, kernel will probe it one by 718 one and will fallback to default. 719 720# Alphabetically sorted list of Non standard 32 bit platforms 721 722config X86_SUPPORTS_MEMORY_FAILURE 723 def_bool y 724 # MCE code calls memory_failure(): 725 depends on X86_MCE 726 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 727 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 728 depends on X86_64 || !SPARSEMEM 729 select ARCH_SUPPORTS_MEMORY_FAILURE 730 731config STA2X11 732 bool "STA2X11 Companion Chip Support" 733 depends on X86_32_NON_STANDARD && PCI 734 select SWIOTLB 735 select MFD_STA2X11 736 select GPIOLIB 737 help 738 This adds support for boards based on the STA2X11 IO-Hub, 739 a.k.a. "ConneXt". The chip is used in place of the standard 740 PC chipset, so all "standard" peripherals are missing. If this 741 option is selected the kernel will still be able to boot on 742 standard PC machines. 743 744config X86_32_IRIS 745 tristate "Eurobraille/Iris poweroff module" 746 depends on X86_32 747 help 748 The Iris machines from EuroBraille do not have APM or ACPI support 749 to shut themselves down properly. A special I/O sequence is 750 needed to do so, which is what this module does at 751 kernel shutdown. 752 753 This is only for Iris machines from EuroBraille. 754 755 If unused, say N. 756 757config SCHED_OMIT_FRAME_POINTER 758 def_bool y 759 prompt "Single-depth WCHAN output" 760 depends on X86 761 help 762 Calculate simpler /proc/<PID>/wchan values. If this option 763 is disabled then wchan values will recurse back to the 764 caller function. This provides more accurate wchan values, 765 at the expense of slightly more scheduling overhead. 766 767 If in doubt, say "Y". 768 769menuconfig HYPERVISOR_GUEST 770 bool "Linux guest support" 771 help 772 Say Y here to enable options for running Linux under various hyper- 773 visors. This option enables basic hypervisor detection and platform 774 setup. 775 776 If you say N, all options in this submenu will be skipped and 777 disabled, and Linux guest support won't be built in. 778 779if HYPERVISOR_GUEST 780 781config PARAVIRT 782 bool "Enable paravirtualization code" 783 depends on HAVE_STATIC_CALL 784 help 785 This changes the kernel so it can modify itself when it is run 786 under a hypervisor, potentially improving performance significantly 787 over full virtualization. However, when run without a hypervisor 788 the kernel is theoretically slower and slightly larger. 789 790config PARAVIRT_XXL 791 bool 792 793config PARAVIRT_DEBUG 794 bool "paravirt-ops debugging" 795 depends on PARAVIRT && DEBUG_KERNEL 796 help 797 Enable to debug paravirt_ops internals. Specifically, BUG if 798 a paravirt_op is missing when it is called. 799 800config PARAVIRT_SPINLOCKS 801 bool "Paravirtualization layer for spinlocks" 802 depends on PARAVIRT && SMP 803 help 804 Paravirtualized spinlocks allow a pvops backend to replace the 805 spinlock implementation with something virtualization-friendly 806 (for example, block the virtual CPU rather than spinning). 807 808 It has a minimal impact on native kernels and gives a nice performance 809 benefit on paravirtualized KVM / Xen kernels. 810 811 If you are unsure how to answer this question, answer Y. 812 813config X86_HV_CALLBACK_VECTOR 814 def_bool n 815 816source "arch/x86/xen/Kconfig" 817 818config KVM_GUEST 819 bool "KVM Guest support (including kvmclock)" 820 depends on PARAVIRT 821 select PARAVIRT_CLOCK 822 select ARCH_CPUIDLE_HALTPOLL 823 select X86_HV_CALLBACK_VECTOR 824 default y 825 help 826 This option enables various optimizations for running under the KVM 827 hypervisor. It includes a paravirtualized clock, so that instead 828 of relying on a PIT (or probably other) emulation by the 829 underlying device model, the host provides the guest with 830 timing infrastructure such as time of day, and system time 831 832config ARCH_CPUIDLE_HALTPOLL 833 def_bool n 834 prompt "Disable host haltpoll when loading haltpoll driver" 835 help 836 If virtualized under KVM, disable host haltpoll. 837 838config PVH 839 bool "Support for running PVH guests" 840 help 841 This option enables the PVH entry point for guest virtual machines 842 as specified in the x86/HVM direct boot ABI. 843 844config PARAVIRT_TIME_ACCOUNTING 845 bool "Paravirtual steal time accounting" 846 depends on PARAVIRT 847 help 848 Select this option to enable fine granularity task steal time 849 accounting. Time spent executing other tasks in parallel with 850 the current vCPU is discounted from the vCPU power. To account for 851 that, there can be a small performance impact. 852 853 If in doubt, say N here. 854 855config PARAVIRT_CLOCK 856 bool 857 858config JAILHOUSE_GUEST 859 bool "Jailhouse non-root cell support" 860 depends on X86_64 && PCI 861 select X86_PM_TIMER 862 help 863 This option allows to run Linux as guest in a Jailhouse non-root 864 cell. You can leave this option disabled if you only want to start 865 Jailhouse and run Linux afterwards in the root cell. 866 867config ACRN_GUEST 868 bool "ACRN Guest support" 869 depends on X86_64 870 select X86_HV_CALLBACK_VECTOR 871 help 872 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 873 a flexible, lightweight reference open-source hypervisor, built with 874 real-time and safety-criticality in mind. It is built for embedded 875 IOT with small footprint and real-time features. More details can be 876 found in https://projectacrn.org/. 877 878config INTEL_TDX_GUEST 879 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 880 depends on X86_64 && CPU_SUP_INTEL 881 depends on X86_X2APIC 882 depends on EFI_STUB 883 select ARCH_HAS_CC_PLATFORM 884 select X86_MEM_ENCRYPT 885 select X86_MCE 886 select UNACCEPTED_MEMORY 887 help 888 Support running as a guest under Intel TDX. Without this support, 889 the guest kernel can not boot or run under TDX. 890 TDX includes memory encryption and integrity capabilities 891 which protect the confidentiality and integrity of guest 892 memory contents and CPU state. TDX guests are protected from 893 some attacks from the VMM. 894 895endif # HYPERVISOR_GUEST 896 897source "arch/x86/Kconfig.cpu" 898 899config HPET_TIMER 900 def_bool X86_64 901 prompt "HPET Timer Support" if X86_32 902 help 903 Use the IA-PC HPET (High Precision Event Timer) to manage 904 time in preference to the PIT and RTC, if a HPET is 905 present. 906 HPET is the next generation timer replacing legacy 8254s. 907 The HPET provides a stable time base on SMP 908 systems, unlike the TSC, but it is more expensive to access, 909 as it is off-chip. The interface used is documented 910 in the HPET spec, revision 1. 911 912 You can safely choose Y here. However, HPET will only be 913 activated if the platform and the BIOS support this feature. 914 Otherwise the 8254 will be used for timing services. 915 916 Choose N to continue using the legacy 8254 timer. 917 918config HPET_EMULATE_RTC 919 def_bool y 920 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 921 922# Mark as expert because too many people got it wrong. 923# The code disables itself when not needed. 924config DMI 925 default y 926 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 927 bool "Enable DMI scanning" if EXPERT 928 help 929 Enabled scanning of DMI to identify machine quirks. Say Y 930 here unless you have verified that your setup is not 931 affected by entries in the DMI blacklist. Required by PNP 932 BIOS code. 933 934config GART_IOMMU 935 bool "Old AMD GART IOMMU support" 936 select DMA_OPS 937 select IOMMU_HELPER 938 select SWIOTLB 939 depends on X86_64 && PCI && AMD_NB 940 help 941 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 942 GART based hardware IOMMUs. 943 944 The GART supports full DMA access for devices with 32-bit access 945 limitations, on systems with more than 3 GB. This is usually needed 946 for USB, sound, many IDE/SATA chipsets and some other devices. 947 948 Newer systems typically have a modern AMD IOMMU, supported via 949 the CONFIG_AMD_IOMMU=y config option. 950 951 In normal configurations this driver is only active when needed: 952 there's more than 3 GB of memory and the system contains a 953 32-bit limited device. 954 955 If unsure, say Y. 956 957config BOOT_VESA_SUPPORT 958 bool 959 help 960 If true, at least one selected framebuffer driver can take advantage 961 of VESA video modes set at an early boot stage via the vga= parameter. 962 963config MAXSMP 964 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 965 depends on X86_64 && SMP && DEBUG_KERNEL 966 select CPUMASK_OFFSTACK 967 help 968 Enable maximum number of CPUS and NUMA Nodes for this architecture. 969 If unsure, say N. 970 971# 972# The maximum number of CPUs supported: 973# 974# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 975# and which can be configured interactively in the 976# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 977# 978# The ranges are different on 32-bit and 64-bit kernels, depending on 979# hardware capabilities and scalability features of the kernel. 980# 981# ( If MAXSMP is enabled we just use the highest possible value and disable 982# interactive configuration. ) 983# 984 985config NR_CPUS_RANGE_BEGIN 986 int 987 default NR_CPUS_RANGE_END if MAXSMP 988 default 1 if !SMP 989 default 2 990 991config NR_CPUS_RANGE_END 992 int 993 depends on X86_32 994 default 64 if SMP && X86_BIGSMP 995 default 8 if SMP && !X86_BIGSMP 996 default 1 if !SMP 997 998config NR_CPUS_RANGE_END 999 int 1000 depends on X86_64 1001 default 8192 if SMP && CPUMASK_OFFSTACK 1002 default 512 if SMP && !CPUMASK_OFFSTACK 1003 default 1 if !SMP 1004 1005config NR_CPUS_DEFAULT 1006 int 1007 depends on X86_32 1008 default 32 if X86_BIGSMP 1009 default 8 if SMP 1010 default 1 if !SMP 1011 1012config NR_CPUS_DEFAULT 1013 int 1014 depends on X86_64 1015 default 8192 if MAXSMP 1016 default 64 if SMP 1017 default 1 if !SMP 1018 1019config NR_CPUS 1020 int "Maximum number of CPUs" if SMP && !MAXSMP 1021 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1022 default NR_CPUS_DEFAULT 1023 help 1024 This allows you to specify the maximum number of CPUs which this 1025 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1026 supported value is 8192, otherwise the maximum value is 512. The 1027 minimum value which makes sense is 2. 1028 1029 This is purely to save memory: each supported CPU adds about 8KB 1030 to the kernel image. 1031 1032config SCHED_CLUSTER 1033 bool "Cluster scheduler support" 1034 depends on SMP 1035 default y 1036 help 1037 Cluster scheduler support improves the CPU scheduler's decision 1038 making when dealing with machines that have clusters of CPUs. 1039 Cluster usually means a couple of CPUs which are placed closely 1040 by sharing mid-level caches, last-level cache tags or internal 1041 busses. 1042 1043config SCHED_SMT 1044 def_bool y if SMP 1045 1046config SCHED_MC 1047 def_bool y 1048 prompt "Multi-core scheduler support" 1049 depends on SMP 1050 help 1051 Multi-core scheduler support improves the CPU scheduler's decision 1052 making when dealing with multi-core CPU chips at a cost of slightly 1053 increased overhead in some places. If unsure say N here. 1054 1055config SCHED_MC_PRIO 1056 bool "CPU core priorities scheduler support" 1057 depends on SCHED_MC && CPU_SUP_INTEL 1058 select X86_INTEL_PSTATE 1059 select CPU_FREQ 1060 default y 1061 help 1062 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1063 core ordering determined at manufacturing time, which allows 1064 certain cores to reach higher turbo frequencies (when running 1065 single threaded workloads) than others. 1066 1067 Enabling this kernel feature teaches the scheduler about 1068 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1069 scheduler's CPU selection logic accordingly, so that higher 1070 overall system performance can be achieved. 1071 1072 This feature will have no effect on CPUs without this feature. 1073 1074 If unsure say Y here. 1075 1076config UP_LATE_INIT 1077 def_bool y 1078 depends on !SMP && X86_LOCAL_APIC 1079 1080config X86_UP_APIC 1081 bool "Local APIC support on uniprocessors" if !PCI_MSI 1082 default PCI_MSI 1083 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1084 help 1085 A local APIC (Advanced Programmable Interrupt Controller) is an 1086 integrated interrupt controller in the CPU. If you have a single-CPU 1087 system which has a processor with a local APIC, you can say Y here to 1088 enable and use it. If you say Y here even though your machine doesn't 1089 have a local APIC, then the kernel will still run with no slowdown at 1090 all. The local APIC supports CPU-generated self-interrupts (timer, 1091 performance counters), and the NMI watchdog which detects hard 1092 lockups. 1093 1094config X86_UP_IOAPIC 1095 bool "IO-APIC support on uniprocessors" 1096 depends on X86_UP_APIC 1097 help 1098 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1099 SMP-capable replacement for PC-style interrupt controllers. Most 1100 SMP systems and many recent uniprocessor systems have one. 1101 1102 If you have a single-CPU system with an IO-APIC, you can say Y here 1103 to use it. If you say Y here even though your machine doesn't have 1104 an IO-APIC, then the kernel will still run with no slowdown at all. 1105 1106config X86_LOCAL_APIC 1107 def_bool y 1108 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1109 select IRQ_DOMAIN_HIERARCHY 1110 1111config X86_IO_APIC 1112 def_bool y 1113 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1114 1115config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1116 bool "Reroute for broken boot IRQs" 1117 depends on X86_IO_APIC 1118 help 1119 This option enables a workaround that fixes a source of 1120 spurious interrupts. This is recommended when threaded 1121 interrupt handling is used on systems where the generation of 1122 superfluous "boot interrupts" cannot be disabled. 1123 1124 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1125 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1126 kernel does during interrupt handling). On chipsets where this 1127 boot IRQ generation cannot be disabled, this workaround keeps 1128 the original IRQ line masked so that only the equivalent "boot 1129 IRQ" is delivered to the CPUs. The workaround also tells the 1130 kernel to set up the IRQ handler on the boot IRQ line. In this 1131 way only one interrupt is delivered to the kernel. Otherwise 1132 the spurious second interrupt may cause the kernel to bring 1133 down (vital) interrupt lines. 1134 1135 Only affects "broken" chipsets. Interrupt sharing may be 1136 increased on these systems. 1137 1138config X86_MCE 1139 bool "Machine Check / overheating reporting" 1140 select GENERIC_ALLOCATOR 1141 default y 1142 help 1143 Machine Check support allows the processor to notify the 1144 kernel if it detects a problem (e.g. overheating, data corruption). 1145 The action the kernel takes depends on the severity of the problem, 1146 ranging from warning messages to halting the machine. 1147 1148config X86_MCELOG_LEGACY 1149 bool "Support for deprecated /dev/mcelog character device" 1150 depends on X86_MCE 1151 help 1152 Enable support for /dev/mcelog which is needed by the old mcelog 1153 userspace logging daemon. Consider switching to the new generation 1154 rasdaemon solution. 1155 1156config X86_MCE_INTEL 1157 def_bool y 1158 prompt "Intel MCE features" 1159 depends on X86_MCE && X86_LOCAL_APIC 1160 help 1161 Additional support for intel specific MCE features such as 1162 the thermal monitor. 1163 1164config X86_MCE_AMD 1165 def_bool y 1166 prompt "AMD MCE features" 1167 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1168 help 1169 Additional support for AMD specific MCE features such as 1170 the DRAM Error Threshold. 1171 1172config X86_ANCIENT_MCE 1173 bool "Support for old Pentium 5 / WinChip machine checks" 1174 depends on X86_32 && X86_MCE 1175 help 1176 Include support for machine check handling on old Pentium 5 or WinChip 1177 systems. These typically need to be enabled explicitly on the command 1178 line. 1179 1180config X86_MCE_THRESHOLD 1181 depends on X86_MCE_AMD || X86_MCE_INTEL 1182 def_bool y 1183 1184config X86_MCE_INJECT 1185 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1186 tristate "Machine check injector support" 1187 help 1188 Provide support for injecting machine checks for testing purposes. 1189 If you don't know what a machine check is and you don't do kernel 1190 QA it is safe to say n. 1191 1192source "arch/x86/events/Kconfig" 1193 1194config X86_LEGACY_VM86 1195 bool "Legacy VM86 support" 1196 depends on X86_32 1197 help 1198 This option allows user programs to put the CPU into V8086 1199 mode, which is an 80286-era approximation of 16-bit real mode. 1200 1201 Some very old versions of X and/or vbetool require this option 1202 for user mode setting. Similarly, DOSEMU will use it if 1203 available to accelerate real mode DOS programs. However, any 1204 recent version of DOSEMU, X, or vbetool should be fully 1205 functional even without kernel VM86 support, as they will all 1206 fall back to software emulation. Nevertheless, if you are using 1207 a 16-bit DOS program where 16-bit performance matters, vm86 1208 mode might be faster than emulation and you might want to 1209 enable this option. 1210 1211 Note that any app that works on a 64-bit kernel is unlikely to 1212 need this option, as 64-bit kernels don't, and can't, support 1213 V8086 mode. This option is also unrelated to 16-bit protected 1214 mode and is not needed to run most 16-bit programs under Wine. 1215 1216 Enabling this option increases the complexity of the kernel 1217 and slows down exception handling a tiny bit. 1218 1219 If unsure, say N here. 1220 1221config VM86 1222 bool 1223 default X86_LEGACY_VM86 1224 1225config X86_16BIT 1226 bool "Enable support for 16-bit segments" if EXPERT 1227 default y 1228 depends on MODIFY_LDT_SYSCALL 1229 help 1230 This option is required by programs like Wine to run 16-bit 1231 protected mode legacy code on x86 processors. Disabling 1232 this option saves about 300 bytes on i386, or around 6K text 1233 plus 16K runtime memory on x86-64, 1234 1235config X86_ESPFIX32 1236 def_bool y 1237 depends on X86_16BIT && X86_32 1238 1239config X86_ESPFIX64 1240 def_bool y 1241 depends on X86_16BIT && X86_64 1242 1243config X86_VSYSCALL_EMULATION 1244 bool "Enable vsyscall emulation" if EXPERT 1245 default y 1246 depends on X86_64 1247 help 1248 This enables emulation of the legacy vsyscall page. Disabling 1249 it is roughly equivalent to booting with vsyscall=none, except 1250 that it will also disable the helpful warning if a program 1251 tries to use a vsyscall. With this option set to N, offending 1252 programs will just segfault, citing addresses of the form 1253 0xffffffffff600?00. 1254 1255 This option is required by many programs built before 2013, and 1256 care should be used even with newer programs if set to N. 1257 1258 Disabling this option saves about 7K of kernel size and 1259 possibly 4K of additional runtime pagetable memory. 1260 1261config X86_IOPL_IOPERM 1262 bool "IOPERM and IOPL Emulation" 1263 default y 1264 help 1265 This enables the ioperm() and iopl() syscalls which are necessary 1266 for legacy applications. 1267 1268 Legacy IOPL support is an overbroad mechanism which allows user 1269 space aside of accessing all 65536 I/O ports also to disable 1270 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1271 capabilities and permission from potentially active security 1272 modules. 1273 1274 The emulation restricts the functionality of the syscall to 1275 only allowing the full range I/O port access, but prevents the 1276 ability to disable interrupts from user space which would be 1277 granted if the hardware IOPL mechanism would be used. 1278 1279config TOSHIBA 1280 tristate "Toshiba Laptop support" 1281 depends on X86_32 1282 help 1283 This adds a driver to safely access the System Management Mode of 1284 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1285 not work on models with a Phoenix BIOS. The System Management Mode 1286 is used to set the BIOS and power saving options on Toshiba portables. 1287 1288 For information on utilities to make use of this driver see the 1289 Toshiba Linux utilities web site at: 1290 <http://www.buzzard.org.uk/toshiba/>. 1291 1292 Say Y if you intend to run this kernel on a Toshiba portable. 1293 Say N otherwise. 1294 1295config X86_REBOOTFIXUPS 1296 bool "Enable X86 board specific fixups for reboot" 1297 depends on X86_32 1298 help 1299 This enables chipset and/or board specific fixups to be done 1300 in order to get reboot to work correctly. This is only needed on 1301 some combinations of hardware and BIOS. The symptom, for which 1302 this config is intended, is when reboot ends with a stalled/hung 1303 system. 1304 1305 Currently, the only fixup is for the Geode machines using 1306 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1307 1308 Say Y if you want to enable the fixup. Currently, it's safe to 1309 enable this option even if you don't need it. 1310 Say N otherwise. 1311 1312config MICROCODE 1313 def_bool y 1314 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1315 1316config MICROCODE_INITRD32 1317 def_bool y 1318 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1319 1320config MICROCODE_LATE_LOADING 1321 bool "Late microcode loading (DANGEROUS)" 1322 default n 1323 depends on MICROCODE && SMP 1324 help 1325 Loading microcode late, when the system is up and executing instructions 1326 is a tricky business and should be avoided if possible. Just the sequence 1327 of synchronizing all cores and SMT threads is one fragile dance which does 1328 not guarantee that cores might not softlock after the loading. Therefore, 1329 use this at your own risk. Late loading taints the kernel unless the 1330 microcode header indicates that it is safe for late loading via the 1331 minimal revision check. This minimal revision check can be enforced on 1332 the kernel command line with "microcode.minrev=Y". 1333 1334config MICROCODE_LATE_FORCE_MINREV 1335 bool "Enforce late microcode loading minimal revision check" 1336 default n 1337 depends on MICROCODE_LATE_LOADING 1338 help 1339 To prevent that users load microcode late which modifies already 1340 in use features, newer microcode patches have a minimum revision field 1341 in the microcode header, which tells the kernel which minimum 1342 revision must be active in the CPU to safely load that new microcode 1343 late into the running system. If disabled the check will not 1344 be enforced but the kernel will be tainted when the minimal 1345 revision check fails. 1346 1347 This minimal revision check can also be controlled via the 1348 "microcode.minrev" parameter on the kernel command line. 1349 1350 If unsure say Y. 1351 1352config X86_MSR 1353 tristate "/dev/cpu/*/msr - Model-specific register support" 1354 help 1355 This device gives privileged processes access to the x86 1356 Model-Specific Registers (MSRs). It is a character device with 1357 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1358 MSR accesses are directed to a specific CPU on multi-processor 1359 systems. 1360 1361config X86_CPUID 1362 tristate "/dev/cpu/*/cpuid - CPU information support" 1363 help 1364 This device gives processes access to the x86 CPUID instruction to 1365 be executed on a specific processor. It is a character device 1366 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1367 /dev/cpu/31/cpuid. 1368 1369choice 1370 prompt "High Memory Support" 1371 default HIGHMEM4G 1372 depends on X86_32 1373 1374config NOHIGHMEM 1375 bool "off" 1376 help 1377 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1378 However, the address space of 32-bit x86 processors is only 4 1379 Gigabytes large. That means that, if you have a large amount of 1380 physical memory, not all of it can be "permanently mapped" by the 1381 kernel. The physical memory that's not permanently mapped is called 1382 "high memory". 1383 1384 If you are compiling a kernel which will never run on a machine with 1385 more than 1 Gigabyte total physical RAM, answer "off" here (default 1386 choice and suitable for most users). This will result in a "3GB/1GB" 1387 split: 3GB are mapped so that each process sees a 3GB virtual memory 1388 space and the remaining part of the 4GB virtual memory space is used 1389 by the kernel to permanently map as much physical memory as 1390 possible. 1391 1392 If the machine has between 1 and 4 Gigabytes physical RAM, then 1393 answer "4GB" here. 1394 1395 If more than 4 Gigabytes is used then answer "64GB" here. This 1396 selection turns Intel PAE (Physical Address Extension) mode on. 1397 PAE implements 3-level paging on IA32 processors. PAE is fully 1398 supported by Linux, PAE mode is implemented on all recent Intel 1399 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1400 then the kernel will not boot on CPUs that don't support PAE! 1401 1402 The actual amount of total physical memory will either be 1403 auto detected or can be forced by using a kernel command line option 1404 such as "mem=256M". (Try "man bootparam" or see the documentation of 1405 your boot loader (lilo or loadlin) about how to pass options to the 1406 kernel at boot time.) 1407 1408 If unsure, say "off". 1409 1410config HIGHMEM4G 1411 bool "4GB" 1412 help 1413 Select this if you have a 32-bit processor and between 1 and 4 1414 gigabytes of physical RAM. 1415 1416config HIGHMEM64G 1417 bool "64GB" 1418 depends on X86_HAVE_PAE 1419 select X86_PAE 1420 help 1421 Select this if you have a 32-bit processor and more than 4 1422 gigabytes of physical RAM. 1423 1424endchoice 1425 1426choice 1427 prompt "Memory split" if EXPERT 1428 default VMSPLIT_3G 1429 depends on X86_32 1430 help 1431 Select the desired split between kernel and user memory. 1432 1433 If the address range available to the kernel is less than the 1434 physical memory installed, the remaining memory will be available 1435 as "high memory". Accessing high memory is a little more costly 1436 than low memory, as it needs to be mapped into the kernel first. 1437 Note that increasing the kernel address space limits the range 1438 available to user programs, making the address space there 1439 tighter. Selecting anything other than the default 3G/1G split 1440 will also likely make your kernel incompatible with binary-only 1441 kernel modules. 1442 1443 If you are not absolutely sure what you are doing, leave this 1444 option alone! 1445 1446 config VMSPLIT_3G 1447 bool "3G/1G user/kernel split" 1448 config VMSPLIT_3G_OPT 1449 depends on !X86_PAE 1450 bool "3G/1G user/kernel split (for full 1G low memory)" 1451 config VMSPLIT_2G 1452 bool "2G/2G user/kernel split" 1453 config VMSPLIT_2G_OPT 1454 depends on !X86_PAE 1455 bool "2G/2G user/kernel split (for full 2G low memory)" 1456 config VMSPLIT_1G 1457 bool "1G/3G user/kernel split" 1458endchoice 1459 1460config PAGE_OFFSET 1461 hex 1462 default 0xB0000000 if VMSPLIT_3G_OPT 1463 default 0x80000000 if VMSPLIT_2G 1464 default 0x78000000 if VMSPLIT_2G_OPT 1465 default 0x40000000 if VMSPLIT_1G 1466 default 0xC0000000 1467 depends on X86_32 1468 1469config HIGHMEM 1470 def_bool y 1471 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1472 1473config X86_PAE 1474 bool "PAE (Physical Address Extension) Support" 1475 depends on X86_32 && X86_HAVE_PAE 1476 select PHYS_ADDR_T_64BIT 1477 select SWIOTLB 1478 help 1479 PAE is required for NX support, and furthermore enables 1480 larger swapspace support for non-overcommit purposes. It 1481 has the cost of more pagetable lookup overhead, and also 1482 consumes more pagetable space per process. 1483 1484config X86_5LEVEL 1485 bool "Enable 5-level page tables support" 1486 default y 1487 select DYNAMIC_MEMORY_LAYOUT 1488 select SPARSEMEM_VMEMMAP 1489 depends on X86_64 1490 help 1491 5-level paging enables access to larger address space: 1492 up to 128 PiB of virtual address space and 4 PiB of 1493 physical address space. 1494 1495 It will be supported by future Intel CPUs. 1496 1497 A kernel with the option enabled can be booted on machines that 1498 support 4- or 5-level paging. 1499 1500 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1501 information. 1502 1503 Say N if unsure. 1504 1505config X86_DIRECT_GBPAGES 1506 def_bool y 1507 depends on X86_64 1508 help 1509 Certain kernel features effectively disable kernel 1510 linear 1 GB mappings (even if the CPU otherwise 1511 supports them), so don't confuse the user by printing 1512 that we have them enabled. 1513 1514config X86_CPA_STATISTICS 1515 bool "Enable statistic for Change Page Attribute" 1516 depends on DEBUG_FS 1517 help 1518 Expose statistics about the Change Page Attribute mechanism, which 1519 helps to determine the effectiveness of preserving large and huge 1520 page mappings when mapping protections are changed. 1521 1522config X86_MEM_ENCRYPT 1523 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1524 select DYNAMIC_PHYSICAL_MASK 1525 def_bool n 1526 1527config AMD_MEM_ENCRYPT 1528 bool "AMD Secure Memory Encryption (SME) support" 1529 depends on X86_64 && CPU_SUP_AMD 1530 depends on EFI_STUB 1531 select DMA_COHERENT_POOL 1532 select ARCH_USE_MEMREMAP_PROT 1533 select INSTRUCTION_DECODER 1534 select ARCH_HAS_CC_PLATFORM 1535 select X86_MEM_ENCRYPT 1536 select UNACCEPTED_MEMORY 1537 help 1538 Say yes to enable support for the encryption of system memory. 1539 This requires an AMD processor that supports Secure Memory 1540 Encryption (SME). 1541 1542config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1543 bool "Activate AMD Secure Memory Encryption (SME) by default" 1544 depends on AMD_MEM_ENCRYPT 1545 help 1546 Say yes to have system memory encrypted by default if running on 1547 an AMD processor that supports Secure Memory Encryption (SME). 1548 1549 If set to Y, then the encryption of system memory can be 1550 deactivated with the mem_encrypt=off command line option. 1551 1552 If set to N, then the encryption of system memory can be 1553 activated with the mem_encrypt=on command line option. 1554 1555# Common NUMA Features 1556config NUMA 1557 bool "NUMA Memory Allocation and Scheduler Support" 1558 depends on SMP 1559 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1560 default y if X86_BIGSMP 1561 select USE_PERCPU_NUMA_NODE_ID 1562 select OF_NUMA if OF 1563 help 1564 Enable NUMA (Non-Uniform Memory Access) support. 1565 1566 The kernel will try to allocate memory used by a CPU on the 1567 local memory controller of the CPU and add some more 1568 NUMA awareness to the kernel. 1569 1570 For 64-bit this is recommended if the system is Intel Core i7 1571 (or later), AMD Opteron, or EM64T NUMA. 1572 1573 For 32-bit this is only needed if you boot a 32-bit 1574 kernel on a 64-bit NUMA platform. 1575 1576 Otherwise, you should say N. 1577 1578config AMD_NUMA 1579 def_bool y 1580 prompt "Old style AMD Opteron NUMA detection" 1581 depends on X86_64 && NUMA && PCI 1582 help 1583 Enable AMD NUMA node topology detection. You should say Y here if 1584 you have a multi processor AMD system. This uses an old method to 1585 read the NUMA configuration directly from the builtin Northbridge 1586 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1587 which also takes priority if both are compiled in. 1588 1589config X86_64_ACPI_NUMA 1590 def_bool y 1591 prompt "ACPI NUMA detection" 1592 depends on X86_64 && NUMA && ACPI && PCI 1593 select ACPI_NUMA 1594 help 1595 Enable ACPI SRAT based node topology detection. 1596 1597config NUMA_EMU 1598 bool "NUMA emulation" 1599 depends on NUMA 1600 help 1601 Enable NUMA emulation. A flat machine will be split 1602 into virtual nodes when booted with "numa=fake=N", where N is the 1603 number of nodes. This is only useful for debugging. 1604 1605config NODES_SHIFT 1606 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1607 range 1 10 1608 default "10" if MAXSMP 1609 default "6" if X86_64 1610 default "3" 1611 depends on NUMA 1612 help 1613 Specify the maximum number of NUMA Nodes available on the target 1614 system. Increases memory reserved to accommodate various tables. 1615 1616config ARCH_FLATMEM_ENABLE 1617 def_bool y 1618 depends on X86_32 && !NUMA 1619 1620config ARCH_SPARSEMEM_ENABLE 1621 def_bool y 1622 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1623 select SPARSEMEM_STATIC if X86_32 1624 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1625 1626config ARCH_SPARSEMEM_DEFAULT 1627 def_bool X86_64 || (NUMA && X86_32) 1628 1629config ARCH_SELECT_MEMORY_MODEL 1630 def_bool y 1631 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1632 1633config ARCH_MEMORY_PROBE 1634 bool "Enable sysfs memory/probe interface" 1635 depends on MEMORY_HOTPLUG 1636 help 1637 This option enables a sysfs memory/probe interface for testing. 1638 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1639 If you are unsure how to answer this question, answer N. 1640 1641config ARCH_PROC_KCORE_TEXT 1642 def_bool y 1643 depends on X86_64 && PROC_KCORE 1644 1645config ILLEGAL_POINTER_VALUE 1646 hex 1647 default 0 if X86_32 1648 default 0xdead000000000000 if X86_64 1649 1650config X86_PMEM_LEGACY_DEVICE 1651 bool 1652 1653config X86_PMEM_LEGACY 1654 tristate "Support non-standard NVDIMMs and ADR protected memory" 1655 depends on PHYS_ADDR_T_64BIT 1656 depends on BLK_DEV 1657 select X86_PMEM_LEGACY_DEVICE 1658 select NUMA_KEEP_MEMINFO if NUMA 1659 select LIBNVDIMM 1660 help 1661 Treat memory marked using the non-standard e820 type of 12 as used 1662 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1663 The kernel will offer these regions to the 'pmem' driver so 1664 they can be used for persistent storage. 1665 1666 Say Y if unsure. 1667 1668config HIGHPTE 1669 bool "Allocate 3rd-level pagetables from highmem" 1670 depends on HIGHMEM 1671 help 1672 The VM uses one page table entry for each page of physical memory. 1673 For systems with a lot of RAM, this can be wasteful of precious 1674 low memory. Setting this option will put user-space page table 1675 entries in high memory. 1676 1677config X86_CHECK_BIOS_CORRUPTION 1678 bool "Check for low memory corruption" 1679 help 1680 Periodically check for memory corruption in low memory, which 1681 is suspected to be caused by BIOS. Even when enabled in the 1682 configuration, it is disabled at runtime. Enable it by 1683 setting "memory_corruption_check=1" on the kernel command 1684 line. By default it scans the low 64k of memory every 60 1685 seconds; see the memory_corruption_check_size and 1686 memory_corruption_check_period parameters in 1687 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1688 1689 When enabled with the default parameters, this option has 1690 almost no overhead, as it reserves a relatively small amount 1691 of memory and scans it infrequently. It both detects corruption 1692 and prevents it from affecting the running system. 1693 1694 It is, however, intended as a diagnostic tool; if repeatable 1695 BIOS-originated corruption always affects the same memory, 1696 you can use memmap= to prevent the kernel from using that 1697 memory. 1698 1699config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1700 bool "Set the default setting of memory_corruption_check" 1701 depends on X86_CHECK_BIOS_CORRUPTION 1702 default y 1703 help 1704 Set whether the default state of memory_corruption_check is 1705 on or off. 1706 1707config MATH_EMULATION 1708 bool 1709 depends on MODIFY_LDT_SYSCALL 1710 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1711 help 1712 Linux can emulate a math coprocessor (used for floating point 1713 operations) if you don't have one. 486DX and Pentium processors have 1714 a math coprocessor built in, 486SX and 386 do not, unless you added 1715 a 487DX or 387, respectively. (The messages during boot time can 1716 give you some hints here ["man dmesg"].) Everyone needs either a 1717 coprocessor or this emulation. 1718 1719 If you don't have a math coprocessor, you need to say Y here; if you 1720 say Y here even though you have a coprocessor, the coprocessor will 1721 be used nevertheless. (This behavior can be changed with the kernel 1722 command line option "no387", which comes handy if your coprocessor 1723 is broken. Try "man bootparam" or see the documentation of your boot 1724 loader (lilo or loadlin) about how to pass options to the kernel at 1725 boot time.) This means that it is a good idea to say Y here if you 1726 intend to use this kernel on different machines. 1727 1728 More information about the internals of the Linux math coprocessor 1729 emulation can be found in <file:arch/x86/math-emu/README>. 1730 1731 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1732 kernel, it won't hurt. 1733 1734config MTRR 1735 def_bool y 1736 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1737 help 1738 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1739 the Memory Type Range Registers (MTRRs) may be used to control 1740 processor access to memory ranges. This is most useful if you have 1741 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1742 allows bus write transfers to be combined into a larger transfer 1743 before bursting over the PCI/AGP bus. This can increase performance 1744 of image write operations 2.5 times or more. Saying Y here creates a 1745 /proc/mtrr file which may be used to manipulate your processor's 1746 MTRRs. Typically the X server should use this. 1747 1748 This code has a reasonably generic interface so that similar 1749 control registers on other processors can be easily supported 1750 as well: 1751 1752 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1753 Registers (ARRs) which provide a similar functionality to MTRRs. For 1754 these, the ARRs are used to emulate the MTRRs. 1755 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1756 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1757 write-combining. All of these processors are supported by this code 1758 and it makes sense to say Y here if you have one of them. 1759 1760 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1761 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1762 can lead to all sorts of problems, so it's good to say Y here. 1763 1764 You can safely say Y even if your machine doesn't have MTRRs, you'll 1765 just add about 9 KB to your kernel. 1766 1767 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1768 1769config MTRR_SANITIZER 1770 def_bool y 1771 prompt "MTRR cleanup support" 1772 depends on MTRR 1773 help 1774 Convert MTRR layout from continuous to discrete, so X drivers can 1775 add writeback entries. 1776 1777 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1778 The largest mtrr entry size for a continuous block can be set with 1779 mtrr_chunk_size. 1780 1781 If unsure, say Y. 1782 1783config MTRR_SANITIZER_ENABLE_DEFAULT 1784 int "MTRR cleanup enable value (0-1)" 1785 range 0 1 1786 default "0" 1787 depends on MTRR_SANITIZER 1788 help 1789 Enable mtrr cleanup default value 1790 1791config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1792 int "MTRR cleanup spare reg num (0-7)" 1793 range 0 7 1794 default "1" 1795 depends on MTRR_SANITIZER 1796 help 1797 mtrr cleanup spare entries default, it can be changed via 1798 mtrr_spare_reg_nr=N on the kernel command line. 1799 1800config X86_PAT 1801 def_bool y 1802 prompt "x86 PAT support" if EXPERT 1803 depends on MTRR 1804 help 1805 Use PAT attributes to setup page level cache control. 1806 1807 PATs are the modern equivalents of MTRRs and are much more 1808 flexible than MTRRs. 1809 1810 Say N here if you see bootup problems (boot crash, boot hang, 1811 spontaneous reboots) or a non-working video driver. 1812 1813 If unsure, say Y. 1814 1815config ARCH_USES_PG_UNCACHED 1816 def_bool y 1817 depends on X86_PAT 1818 1819config X86_UMIP 1820 def_bool y 1821 prompt "User Mode Instruction Prevention" if EXPERT 1822 help 1823 User Mode Instruction Prevention (UMIP) is a security feature in 1824 some x86 processors. If enabled, a general protection fault is 1825 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1826 executed in user mode. These instructions unnecessarily expose 1827 information about the hardware state. 1828 1829 The vast majority of applications do not use these instructions. 1830 For the very few that do, software emulation is provided in 1831 specific cases in protected and virtual-8086 modes. Emulated 1832 results are dummy. 1833 1834config CC_HAS_IBT 1835 # GCC >= 9 and binutils >= 2.29 1836 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1837 # Clang/LLVM >= 14 1838 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1839 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1840 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1841 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1842 $(as-instr,endbr64) 1843 1844config X86_CET 1845 def_bool n 1846 help 1847 CET features configured (Shadow stack or IBT) 1848 1849config X86_KERNEL_IBT 1850 prompt "Indirect Branch Tracking" 1851 def_bool y 1852 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1853 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1854 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1855 select OBJTOOL 1856 select X86_CET 1857 help 1858 Build the kernel with support for Indirect Branch Tracking, a 1859 hardware support course-grain forward-edge Control Flow Integrity 1860 protection. It enforces that all indirect calls must land on 1861 an ENDBR instruction, as such, the compiler will instrument the 1862 code with them to make this happen. 1863 1864 In addition to building the kernel with IBT, seal all functions that 1865 are not indirect call targets, avoiding them ever becoming one. 1866 1867 This requires LTO like objtool runs and will slow down the build. It 1868 does significantly reduce the number of ENDBR instructions in the 1869 kernel image. 1870 1871config X86_INTEL_MEMORY_PROTECTION_KEYS 1872 prompt "Memory Protection Keys" 1873 def_bool y 1874 # Note: only available in 64-bit mode 1875 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1876 select ARCH_USES_HIGH_VMA_FLAGS 1877 select ARCH_HAS_PKEYS 1878 help 1879 Memory Protection Keys provides a mechanism for enforcing 1880 page-based protections, but without requiring modification of the 1881 page tables when an application changes protection domains. 1882 1883 For details, see Documentation/core-api/protection-keys.rst 1884 1885 If unsure, say y. 1886 1887choice 1888 prompt "TSX enable mode" 1889 depends on CPU_SUP_INTEL 1890 default X86_INTEL_TSX_MODE_OFF 1891 help 1892 Intel's TSX (Transactional Synchronization Extensions) feature 1893 allows to optimize locking protocols through lock elision which 1894 can lead to a noticeable performance boost. 1895 1896 On the other hand it has been shown that TSX can be exploited 1897 to form side channel attacks (e.g. TAA) and chances are there 1898 will be more of those attacks discovered in the future. 1899 1900 Therefore TSX is not enabled by default (aka tsx=off). An admin 1901 might override this decision by tsx=on the command line parameter. 1902 Even with TSX enabled, the kernel will attempt to enable the best 1903 possible TAA mitigation setting depending on the microcode available 1904 for the particular machine. 1905 1906 This option allows to set the default tsx mode between tsx=on, =off 1907 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1908 details. 1909 1910 Say off if not sure, auto if TSX is in use but it should be used on safe 1911 platforms or on if TSX is in use and the security aspect of tsx is not 1912 relevant. 1913 1914config X86_INTEL_TSX_MODE_OFF 1915 bool "off" 1916 help 1917 TSX is disabled if possible - equals to tsx=off command line parameter. 1918 1919config X86_INTEL_TSX_MODE_ON 1920 bool "on" 1921 help 1922 TSX is always enabled on TSX capable HW - equals the tsx=on command 1923 line parameter. 1924 1925config X86_INTEL_TSX_MODE_AUTO 1926 bool "auto" 1927 help 1928 TSX is enabled on TSX capable HW that is believed to be safe against 1929 side channel attacks- equals the tsx=auto command line parameter. 1930endchoice 1931 1932config X86_SGX 1933 bool "Software Guard eXtensions (SGX)" 1934 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1935 depends on CRYPTO=y 1936 depends on CRYPTO_SHA256=y 1937 select MMU_NOTIFIER 1938 select NUMA_KEEP_MEMINFO if NUMA 1939 select XARRAY_MULTI 1940 help 1941 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1942 that can be used by applications to set aside private regions of code 1943 and data, referred to as enclaves. An enclave's private memory can 1944 only be accessed by code running within the enclave. Accesses from 1945 outside the enclave, including other enclaves, are disallowed by 1946 hardware. 1947 1948 If unsure, say N. 1949 1950config X86_USER_SHADOW_STACK 1951 bool "X86 userspace shadow stack" 1952 depends on AS_WRUSS 1953 depends on X86_64 1954 select ARCH_USES_HIGH_VMA_FLAGS 1955 select X86_CET 1956 help 1957 Shadow stack protection is a hardware feature that detects function 1958 return address corruption. This helps mitigate ROP attacks. 1959 Applications must be enabled to use it, and old userspace does not 1960 get protection "for free". 1961 1962 CPUs supporting shadow stacks were first released in 2020. 1963 1964 See Documentation/arch/x86/shstk.rst for more information. 1965 1966 If unsure, say N. 1967 1968config INTEL_TDX_HOST 1969 bool "Intel Trust Domain Extensions (TDX) host support" 1970 depends on CPU_SUP_INTEL 1971 depends on X86_64 1972 depends on KVM_INTEL 1973 depends on X86_X2APIC 1974 select ARCH_KEEP_MEMBLOCK 1975 depends on CONTIG_ALLOC 1976 depends on !KEXEC_CORE 1977 depends on X86_MCE 1978 help 1979 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1980 host and certain physical attacks. This option enables necessary TDX 1981 support in the host kernel to run confidential VMs. 1982 1983 If unsure, say N. 1984 1985config EFI 1986 bool "EFI runtime service support" 1987 depends on ACPI 1988 select UCS2_STRING 1989 select EFI_RUNTIME_WRAPPERS 1990 select ARCH_USE_MEMREMAP_PROT 1991 select EFI_RUNTIME_MAP if KEXEC_CORE 1992 help 1993 This enables the kernel to use EFI runtime services that are 1994 available (such as the EFI variable services). 1995 1996 This option is only useful on systems that have EFI firmware. 1997 In addition, you should use the latest ELILO loader available 1998 at <http://elilo.sourceforge.net> in order to take advantage 1999 of EFI runtime services. However, even with this option, the 2000 resultant kernel should continue to boot on existing non-EFI 2001 platforms. 2002 2003config EFI_STUB 2004 bool "EFI stub support" 2005 depends on EFI 2006 select RELOCATABLE 2007 help 2008 This kernel feature allows a bzImage to be loaded directly 2009 by EFI firmware without the use of a bootloader. 2010 2011 See Documentation/admin-guide/efi-stub.rst for more information. 2012 2013config EFI_HANDOVER_PROTOCOL 2014 bool "EFI handover protocol (DEPRECATED)" 2015 depends on EFI_STUB 2016 default y 2017 help 2018 Select this in order to include support for the deprecated EFI 2019 handover protocol, which defines alternative entry points into the 2020 EFI stub. This is a practice that has no basis in the UEFI 2021 specification, and requires a priori knowledge on the part of the 2022 bootloader about Linux/x86 specific ways of passing the command line 2023 and initrd, and where in memory those assets may be loaded. 2024 2025 If in doubt, say Y. Even though the corresponding support is not 2026 present in upstream GRUB or other bootloaders, most distros build 2027 GRUB with numerous downstream patches applied, and may rely on the 2028 handover protocol as as result. 2029 2030config EFI_MIXED 2031 bool "EFI mixed-mode support" 2032 depends on EFI_STUB && X86_64 2033 help 2034 Enabling this feature allows a 64-bit kernel to be booted 2035 on a 32-bit firmware, provided that your CPU supports 64-bit 2036 mode. 2037 2038 Note that it is not possible to boot a mixed-mode enabled 2039 kernel via the EFI boot stub - a bootloader that supports 2040 the EFI handover protocol must be used. 2041 2042 If unsure, say N. 2043 2044config EFI_FAKE_MEMMAP 2045 bool "Enable EFI fake memory map" 2046 depends on EFI 2047 help 2048 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2049 this parameter, you can add arbitrary attribute to specific memory 2050 range by updating original (firmware provided) EFI memmap. This is 2051 useful for debugging of EFI memmap related feature, e.g., Address 2052 Range Mirroring feature. 2053 2054config EFI_MAX_FAKE_MEM 2055 int "maximum allowable number of ranges in efi_fake_mem boot option" 2056 depends on EFI_FAKE_MEMMAP 2057 range 1 128 2058 default 8 2059 help 2060 Maximum allowable number of ranges in efi_fake_mem boot option. 2061 Ranges can be set up to this value using comma-separated list. 2062 The default value is 8. 2063 2064config EFI_RUNTIME_MAP 2065 bool "Export EFI runtime maps to sysfs" if EXPERT 2066 depends on EFI 2067 help 2068 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2069 That memory map is required by the 2nd kernel to set up EFI virtual 2070 mappings after kexec, but can also be used for debugging purposes. 2071 2072 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2073 2074source "kernel/Kconfig.hz" 2075 2076config ARCH_SUPPORTS_KEXEC 2077 def_bool y 2078 2079config ARCH_SUPPORTS_KEXEC_FILE 2080 def_bool X86_64 2081 2082config ARCH_SELECTS_KEXEC_FILE 2083 def_bool y 2084 depends on KEXEC_FILE 2085 select HAVE_IMA_KEXEC if IMA 2086 2087config ARCH_SUPPORTS_KEXEC_PURGATORY 2088 def_bool y 2089 2090config ARCH_SUPPORTS_KEXEC_SIG 2091 def_bool y 2092 2093config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2094 def_bool y 2095 2096config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2097 def_bool y 2098 2099config ARCH_SUPPORTS_KEXEC_JUMP 2100 def_bool y 2101 2102config ARCH_SUPPORTS_CRASH_DUMP 2103 def_bool X86_64 || (X86_32 && HIGHMEM) 2104 2105config ARCH_SUPPORTS_CRASH_HOTPLUG 2106 def_bool y 2107 2108config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2109 def_bool CRASH_CORE 2110 2111config PHYSICAL_START 2112 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2113 default "0x1000000" 2114 help 2115 This gives the physical address where the kernel is loaded. 2116 2117 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2118 bzImage will decompress itself to above physical address and 2119 run from there. Otherwise, bzImage will run from the address where 2120 it has been loaded by the boot loader and will ignore above physical 2121 address. 2122 2123 In normal kdump cases one does not have to set/change this option 2124 as now bzImage can be compiled as a completely relocatable image 2125 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2126 address. This option is mainly useful for the folks who don't want 2127 to use a bzImage for capturing the crash dump and want to use a 2128 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2129 to be specifically compiled to run from a specific memory area 2130 (normally a reserved region) and this option comes handy. 2131 2132 So if you are using bzImage for capturing the crash dump, 2133 leave the value here unchanged to 0x1000000 and set 2134 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2135 for capturing the crash dump change this value to start of 2136 the reserved region. In other words, it can be set based on 2137 the "X" value as specified in the "crashkernel=YM@XM" 2138 command line boot parameter passed to the panic-ed 2139 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2140 for more details about crash dumps. 2141 2142 Usage of bzImage for capturing the crash dump is recommended as 2143 one does not have to build two kernels. Same kernel can be used 2144 as production kernel and capture kernel. Above option should have 2145 gone away after relocatable bzImage support is introduced. But it 2146 is present because there are users out there who continue to use 2147 vmlinux for dump capture. This option should go away down the 2148 line. 2149 2150 Don't change this unless you know what you are doing. 2151 2152config RELOCATABLE 2153 bool "Build a relocatable kernel" 2154 default y 2155 help 2156 This builds a kernel image that retains relocation information 2157 so it can be loaded someplace besides the default 1MB. 2158 The relocations tend to make the kernel binary about 10% larger, 2159 but are discarded at runtime. 2160 2161 One use is for the kexec on panic case where the recovery kernel 2162 must live at a different physical address than the primary 2163 kernel. 2164 2165 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2166 it has been loaded at and the compile time physical address 2167 (CONFIG_PHYSICAL_START) is used as the minimum location. 2168 2169config RANDOMIZE_BASE 2170 bool "Randomize the address of the kernel image (KASLR)" 2171 depends on RELOCATABLE 2172 default y 2173 help 2174 In support of Kernel Address Space Layout Randomization (KASLR), 2175 this randomizes the physical address at which the kernel image 2176 is decompressed and the virtual address where the kernel 2177 image is mapped, as a security feature that deters exploit 2178 attempts relying on knowledge of the location of kernel 2179 code internals. 2180 2181 On 64-bit, the kernel physical and virtual addresses are 2182 randomized separately. The physical address will be anywhere 2183 between 16MB and the top of physical memory (up to 64TB). The 2184 virtual address will be randomized from 16MB up to 1GB (9 bits 2185 of entropy). Note that this also reduces the memory space 2186 available to kernel modules from 1.5GB to 1GB. 2187 2188 On 32-bit, the kernel physical and virtual addresses are 2189 randomized together. They will be randomized from 16MB up to 2190 512MB (8 bits of entropy). 2191 2192 Entropy is generated using the RDRAND instruction if it is 2193 supported. If RDTSC is supported, its value is mixed into 2194 the entropy pool as well. If neither RDRAND nor RDTSC are 2195 supported, then entropy is read from the i8254 timer. The 2196 usable entropy is limited by the kernel being built using 2197 2GB addressing, and that PHYSICAL_ALIGN must be at a 2198 minimum of 2MB. As a result, only 10 bits of entropy are 2199 theoretically possible, but the implementations are further 2200 limited due to memory layouts. 2201 2202 If unsure, say Y. 2203 2204# Relocation on x86 needs some additional build support 2205config X86_NEED_RELOCS 2206 def_bool y 2207 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2208 2209config PHYSICAL_ALIGN 2210 hex "Alignment value to which kernel should be aligned" 2211 default "0x200000" 2212 range 0x2000 0x1000000 if X86_32 2213 range 0x200000 0x1000000 if X86_64 2214 help 2215 This value puts the alignment restrictions on physical address 2216 where kernel is loaded and run from. Kernel is compiled for an 2217 address which meets above alignment restriction. 2218 2219 If bootloader loads the kernel at a non-aligned address and 2220 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2221 address aligned to above value and run from there. 2222 2223 If bootloader loads the kernel at a non-aligned address and 2224 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2225 load address and decompress itself to the address it has been 2226 compiled for and run from there. The address for which kernel is 2227 compiled already meets above alignment restrictions. Hence the 2228 end result is that kernel runs from a physical address meeting 2229 above alignment restrictions. 2230 2231 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2232 this value must be a multiple of 0x200000. 2233 2234 Don't change this unless you know what you are doing. 2235 2236config DYNAMIC_MEMORY_LAYOUT 2237 bool 2238 help 2239 This option makes base addresses of vmalloc and vmemmap as well as 2240 __PAGE_OFFSET movable during boot. 2241 2242config RANDOMIZE_MEMORY 2243 bool "Randomize the kernel memory sections" 2244 depends on X86_64 2245 depends on RANDOMIZE_BASE 2246 select DYNAMIC_MEMORY_LAYOUT 2247 default RANDOMIZE_BASE 2248 help 2249 Randomizes the base virtual address of kernel memory sections 2250 (physical memory mapping, vmalloc & vmemmap). This security feature 2251 makes exploits relying on predictable memory locations less reliable. 2252 2253 The order of allocations remains unchanged. Entropy is generated in 2254 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2255 configuration have in average 30,000 different possible virtual 2256 addresses for each memory section. 2257 2258 If unsure, say Y. 2259 2260config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2261 hex "Physical memory mapping padding" if EXPERT 2262 depends on RANDOMIZE_MEMORY 2263 default "0xa" if MEMORY_HOTPLUG 2264 default "0x0" 2265 range 0x1 0x40 if MEMORY_HOTPLUG 2266 range 0x0 0x40 2267 help 2268 Define the padding in terabytes added to the existing physical 2269 memory size during kernel memory randomization. It is useful 2270 for memory hotplug support but reduces the entropy available for 2271 address randomization. 2272 2273 If unsure, leave at the default value. 2274 2275config ADDRESS_MASKING 2276 bool "Linear Address Masking support" 2277 depends on X86_64 2278 help 2279 Linear Address Masking (LAM) modifies the checking that is applied 2280 to 64-bit linear addresses, allowing software to use of the 2281 untranslated address bits for metadata. 2282 2283 The capability can be used for efficient address sanitizers (ASAN) 2284 implementation and for optimizations in JITs. 2285 2286config HOTPLUG_CPU 2287 def_bool y 2288 depends on SMP 2289 2290config COMPAT_VDSO 2291 def_bool n 2292 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2293 depends on COMPAT_32 2294 help 2295 Certain buggy versions of glibc will crash if they are 2296 presented with a 32-bit vDSO that is not mapped at the address 2297 indicated in its segment table. 2298 2299 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2300 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2301 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2302 the only released version with the bug, but OpenSUSE 9 2303 contains a buggy "glibc 2.3.2". 2304 2305 The symptom of the bug is that everything crashes on startup, saying: 2306 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2307 2308 Saying Y here changes the default value of the vdso32 boot 2309 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2310 This works around the glibc bug but hurts performance. 2311 2312 If unsure, say N: if you are compiling your own kernel, you 2313 are unlikely to be using a buggy version of glibc. 2314 2315choice 2316 prompt "vsyscall table for legacy applications" 2317 depends on X86_64 2318 default LEGACY_VSYSCALL_XONLY 2319 help 2320 Legacy user code that does not know how to find the vDSO expects 2321 to be able to issue three syscalls by calling fixed addresses in 2322 kernel space. Since this location is not randomized with ASLR, 2323 it can be used to assist security vulnerability exploitation. 2324 2325 This setting can be changed at boot time via the kernel command 2326 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2327 is deprecated and can only be enabled using the kernel command 2328 line. 2329 2330 On a system with recent enough glibc (2.14 or newer) and no 2331 static binaries, you can say None without a performance penalty 2332 to improve security. 2333 2334 If unsure, select "Emulate execution only". 2335 2336 config LEGACY_VSYSCALL_XONLY 2337 bool "Emulate execution only" 2338 help 2339 The kernel traps and emulates calls into the fixed vsyscall 2340 address mapping and does not allow reads. This 2341 configuration is recommended when userspace might use the 2342 legacy vsyscall area but support for legacy binary 2343 instrumentation of legacy code is not needed. It mitigates 2344 certain uses of the vsyscall area as an ASLR-bypassing 2345 buffer. 2346 2347 config LEGACY_VSYSCALL_NONE 2348 bool "None" 2349 help 2350 There will be no vsyscall mapping at all. This will 2351 eliminate any risk of ASLR bypass due to the vsyscall 2352 fixed address mapping. Attempts to use the vsyscalls 2353 will be reported to dmesg, so that either old or 2354 malicious userspace programs can be identified. 2355 2356endchoice 2357 2358config CMDLINE_BOOL 2359 bool "Built-in kernel command line" 2360 help 2361 Allow for specifying boot arguments to the kernel at 2362 build time. On some systems (e.g. embedded ones), it is 2363 necessary or convenient to provide some or all of the 2364 kernel boot arguments with the kernel itself (that is, 2365 to not rely on the boot loader to provide them.) 2366 2367 To compile command line arguments into the kernel, 2368 set this option to 'Y', then fill in the 2369 boot arguments in CONFIG_CMDLINE. 2370 2371 Systems with fully functional boot loaders (i.e. non-embedded) 2372 should leave this option set to 'N'. 2373 2374config CMDLINE 2375 string "Built-in kernel command string" 2376 depends on CMDLINE_BOOL 2377 default "" 2378 help 2379 Enter arguments here that should be compiled into the kernel 2380 image and used at boot time. If the boot loader provides a 2381 command line at boot time, it is appended to this string to 2382 form the full kernel command line, when the system boots. 2383 2384 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2385 change this behavior. 2386 2387 In most cases, the command line (whether built-in or provided 2388 by the boot loader) should specify the device for the root 2389 file system. 2390 2391config CMDLINE_OVERRIDE 2392 bool "Built-in command line overrides boot loader arguments" 2393 depends on CMDLINE_BOOL && CMDLINE != "" 2394 help 2395 Set this option to 'Y' to have the kernel ignore the boot loader 2396 command line, and use ONLY the built-in command line. 2397 2398 This is used to work around broken boot loaders. This should 2399 be set to 'N' under normal conditions. 2400 2401config MODIFY_LDT_SYSCALL 2402 bool "Enable the LDT (local descriptor table)" if EXPERT 2403 default y 2404 help 2405 Linux can allow user programs to install a per-process x86 2406 Local Descriptor Table (LDT) using the modify_ldt(2) system 2407 call. This is required to run 16-bit or segmented code such as 2408 DOSEMU or some Wine programs. It is also used by some very old 2409 threading libraries. 2410 2411 Enabling this feature adds a small amount of overhead to 2412 context switches and increases the low-level kernel attack 2413 surface. Disabling it removes the modify_ldt(2) system call. 2414 2415 Saying 'N' here may make sense for embedded or server kernels. 2416 2417config STRICT_SIGALTSTACK_SIZE 2418 bool "Enforce strict size checking for sigaltstack" 2419 depends on DYNAMIC_SIGFRAME 2420 help 2421 For historical reasons MINSIGSTKSZ is a constant which became 2422 already too small with AVX512 support. Add a mechanism to 2423 enforce strict checking of the sigaltstack size against the 2424 real size of the FPU frame. This option enables the check 2425 by default. It can also be controlled via the kernel command 2426 line option 'strict_sas_size' independent of this config 2427 switch. Enabling it might break existing applications which 2428 allocate a too small sigaltstack but 'work' because they 2429 never get a signal delivered. 2430 2431 Say 'N' unless you want to really enforce this check. 2432 2433source "kernel/livepatch/Kconfig" 2434 2435endmenu 2436 2437config CC_HAS_SLS 2438 def_bool $(cc-option,-mharden-sls=all) 2439 2440config CC_HAS_RETURN_THUNK 2441 def_bool $(cc-option,-mfunction-return=thunk-extern) 2442 2443config CC_HAS_ENTRY_PADDING 2444 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2445 2446config FUNCTION_PADDING_CFI 2447 int 2448 default 59 if FUNCTION_ALIGNMENT_64B 2449 default 27 if FUNCTION_ALIGNMENT_32B 2450 default 11 if FUNCTION_ALIGNMENT_16B 2451 default 3 if FUNCTION_ALIGNMENT_8B 2452 default 0 2453 2454# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2455# except Kconfig can't do arithmetic :/ 2456config FUNCTION_PADDING_BYTES 2457 int 2458 default FUNCTION_PADDING_CFI if CFI_CLANG 2459 default FUNCTION_ALIGNMENT 2460 2461config CALL_PADDING 2462 def_bool n 2463 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2464 select FUNCTION_ALIGNMENT_16B 2465 2466config FINEIBT 2467 def_bool y 2468 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE 2469 select CALL_PADDING 2470 2471config HAVE_CALL_THUNKS 2472 def_bool y 2473 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL 2474 2475config CALL_THUNKS 2476 def_bool n 2477 select CALL_PADDING 2478 2479config PREFIX_SYMBOLS 2480 def_bool y 2481 depends on CALL_PADDING && !CFI_CLANG 2482 2483menuconfig SPECULATION_MITIGATIONS 2484 bool "Mitigations for speculative execution vulnerabilities" 2485 default y 2486 help 2487 Say Y here to enable options which enable mitigations for 2488 speculative execution hardware vulnerabilities. 2489 2490 If you say N, all mitigations will be disabled. You really 2491 should know what you are doing to say so. 2492 2493if SPECULATION_MITIGATIONS 2494 2495config PAGE_TABLE_ISOLATION 2496 bool "Remove the kernel mapping in user mode" 2497 default y 2498 depends on (X86_64 || X86_PAE) 2499 help 2500 This feature reduces the number of hardware side channels by 2501 ensuring that the majority of kernel addresses are not mapped 2502 into userspace. 2503 2504 See Documentation/arch/x86/pti.rst for more details. 2505 2506config RETPOLINE 2507 bool "Avoid speculative indirect branches in kernel" 2508 select OBJTOOL if HAVE_OBJTOOL 2509 default y 2510 help 2511 Compile kernel with the retpoline compiler options to guard against 2512 kernel-to-user data leaks by avoiding speculative indirect 2513 branches. Requires a compiler with -mindirect-branch=thunk-extern 2514 support for full protection. The kernel may run slower. 2515 2516config RETHUNK 2517 bool "Enable return-thunks" 2518 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2519 select OBJTOOL if HAVE_OBJTOOL 2520 default y if X86_64 2521 help 2522 Compile the kernel with the return-thunks compiler option to guard 2523 against kernel-to-user data leaks by avoiding return speculation. 2524 Requires a compiler with -mfunction-return=thunk-extern 2525 support for full protection. The kernel may run slower. 2526 2527config CPU_UNRET_ENTRY 2528 bool "Enable UNRET on kernel entry" 2529 depends on CPU_SUP_AMD && RETHUNK && X86_64 2530 default y 2531 help 2532 Compile the kernel with support for the retbleed=unret mitigation. 2533 2534config CALL_DEPTH_TRACKING 2535 bool "Mitigate RSB underflow with call depth tracking" 2536 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2537 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2538 select CALL_THUNKS 2539 default y 2540 help 2541 Compile the kernel with call depth tracking to mitigate the Intel 2542 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2543 mitigation is off by default and needs to be enabled on the 2544 kernel command line via the retbleed=stuff option. For 2545 non-affected systems the overhead of this option is marginal as 2546 the call depth tracking is using run-time generated call thunks 2547 in a compiler generated padding area and call patching. This 2548 increases text size by ~5%. For non affected systems this space 2549 is unused. On affected SKL systems this results in a significant 2550 performance gain over the IBRS mitigation. 2551 2552config CALL_THUNKS_DEBUG 2553 bool "Enable call thunks and call depth tracking debugging" 2554 depends on CALL_DEPTH_TRACKING 2555 select FUNCTION_ALIGNMENT_32B 2556 default n 2557 help 2558 Enable call/ret counters for imbalance detection and build in 2559 a noisy dmesg about callthunks generation and call patching for 2560 trouble shooting. The debug prints need to be enabled on the 2561 kernel command line with 'debug-callthunks'. 2562 Only enable this when you are debugging call thunks as this 2563 creates a noticeable runtime overhead. If unsure say N. 2564 2565config CPU_IBPB_ENTRY 2566 bool "Enable IBPB on kernel entry" 2567 depends on CPU_SUP_AMD && X86_64 2568 default y 2569 help 2570 Compile the kernel with support for the retbleed=ibpb mitigation. 2571 2572config CPU_IBRS_ENTRY 2573 bool "Enable IBRS on kernel entry" 2574 depends on CPU_SUP_INTEL && X86_64 2575 default y 2576 help 2577 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2578 This mitigates both spectre_v2 and retbleed at great cost to 2579 performance. 2580 2581config CPU_SRSO 2582 bool "Mitigate speculative RAS overflow on AMD" 2583 depends on CPU_SUP_AMD && X86_64 && RETHUNK 2584 default y 2585 help 2586 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2587 2588config SLS 2589 bool "Mitigate Straight-Line-Speculation" 2590 depends on CC_HAS_SLS && X86_64 2591 select OBJTOOL if HAVE_OBJTOOL 2592 default n 2593 help 2594 Compile the kernel with straight-line-speculation options to guard 2595 against straight line speculation. The kernel image might be slightly 2596 larger. 2597 2598config GDS_FORCE_MITIGATION 2599 bool "Force GDS Mitigation" 2600 depends on CPU_SUP_INTEL 2601 default n 2602 help 2603 Gather Data Sampling (GDS) is a hardware vulnerability which allows 2604 unprivileged speculative access to data which was previously stored in 2605 vector registers. 2606 2607 This option is equivalent to setting gather_data_sampling=force on the 2608 command line. The microcode mitigation is used if present, otherwise 2609 AVX is disabled as a mitigation. On affected systems that are missing 2610 the microcode any userspace code that unconditionally uses AVX will 2611 break with this option set. 2612 2613 Setting this option on systems not vulnerable to GDS has no effect. 2614 2615 If in doubt, say N. 2616 2617endif 2618 2619config ARCH_HAS_ADD_PAGES 2620 def_bool y 2621 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2622 2623menu "Power management and ACPI options" 2624 2625config ARCH_HIBERNATION_HEADER 2626 def_bool y 2627 depends on HIBERNATION 2628 2629source "kernel/power/Kconfig" 2630 2631source "drivers/acpi/Kconfig" 2632 2633config X86_APM_BOOT 2634 def_bool y 2635 depends on APM 2636 2637menuconfig APM 2638 tristate "APM (Advanced Power Management) BIOS support" 2639 depends on X86_32 && PM_SLEEP 2640 help 2641 APM is a BIOS specification for saving power using several different 2642 techniques. This is mostly useful for battery powered laptops with 2643 APM compliant BIOSes. If you say Y here, the system time will be 2644 reset after a RESUME operation, the /proc/apm device will provide 2645 battery status information, and user-space programs will receive 2646 notification of APM "events" (e.g. battery status change). 2647 2648 If you select "Y" here, you can disable actual use of the APM 2649 BIOS by passing the "apm=off" option to the kernel at boot time. 2650 2651 Note that the APM support is almost completely disabled for 2652 machines with more than one CPU. 2653 2654 In order to use APM, you will need supporting software. For location 2655 and more information, read <file:Documentation/power/apm-acpi.rst> 2656 and the Battery Powered Linux mini-HOWTO, available from 2657 <http://www.tldp.org/docs.html#howto>. 2658 2659 This driver does not spin down disk drives (see the hdparm(8) 2660 manpage ("man 8 hdparm") for that), and it doesn't turn off 2661 VESA-compliant "green" monitors. 2662 2663 This driver does not support the TI 4000M TravelMate and the ACER 2664 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2665 desktop machines also don't have compliant BIOSes, and this driver 2666 may cause those machines to panic during the boot phase. 2667 2668 Generally, if you don't have a battery in your machine, there isn't 2669 much point in using this driver and you should say N. If you get 2670 random kernel OOPSes or reboots that don't seem to be related to 2671 anything, try disabling/enabling this option (or disabling/enabling 2672 APM in your BIOS). 2673 2674 Some other things you should try when experiencing seemingly random, 2675 "weird" problems: 2676 2677 1) make sure that you have enough swap space and that it is 2678 enabled. 2679 2) pass the "idle=poll" option to the kernel 2680 3) switch on floating point emulation in the kernel and pass 2681 the "no387" option to the kernel 2682 4) pass the "floppy=nodma" option to the kernel 2683 5) pass the "mem=4M" option to the kernel (thereby disabling 2684 all but the first 4 MB of RAM) 2685 6) make sure that the CPU is not over clocked. 2686 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2687 8) disable the cache from your BIOS settings 2688 9) install a fan for the video card or exchange video RAM 2689 10) install a better fan for the CPU 2690 11) exchange RAM chips 2691 12) exchange the motherboard. 2692 2693 To compile this driver as a module, choose M here: the 2694 module will be called apm. 2695 2696if APM 2697 2698config APM_IGNORE_USER_SUSPEND 2699 bool "Ignore USER SUSPEND" 2700 help 2701 This option will ignore USER SUSPEND requests. On machines with a 2702 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2703 series notebooks, it is necessary to say Y because of a BIOS bug. 2704 2705config APM_DO_ENABLE 2706 bool "Enable PM at boot time" 2707 help 2708 Enable APM features at boot time. From page 36 of the APM BIOS 2709 specification: "When disabled, the APM BIOS does not automatically 2710 power manage devices, enter the Standby State, enter the Suspend 2711 State, or take power saving steps in response to CPU Idle calls." 2712 This driver will make CPU Idle calls when Linux is idle (unless this 2713 feature is turned off -- see "Do CPU IDLE calls", below). This 2714 should always save battery power, but more complicated APM features 2715 will be dependent on your BIOS implementation. You may need to turn 2716 this option off if your computer hangs at boot time when using APM 2717 support, or if it beeps continuously instead of suspending. Turn 2718 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2719 T400CDT. This is off by default since most machines do fine without 2720 this feature. 2721 2722config APM_CPU_IDLE 2723 depends on CPU_IDLE 2724 bool "Make CPU Idle calls when idle" 2725 help 2726 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2727 On some machines, this can activate improved power savings, such as 2728 a slowed CPU clock rate, when the machine is idle. These idle calls 2729 are made after the idle loop has run for some length of time (e.g., 2730 333 mS). On some machines, this will cause a hang at boot time or 2731 whenever the CPU becomes idle. (On machines with more than one CPU, 2732 this option does nothing.) 2733 2734config APM_DISPLAY_BLANK 2735 bool "Enable console blanking using APM" 2736 help 2737 Enable console blanking using the APM. Some laptops can use this to 2738 turn off the LCD backlight when the screen blanker of the Linux 2739 virtual console blanks the screen. Note that this is only used by 2740 the virtual console screen blanker, and won't turn off the backlight 2741 when using the X Window system. This also doesn't have anything to 2742 do with your VESA-compliant power-saving monitor. Further, this 2743 option doesn't work for all laptops -- it might not turn off your 2744 backlight at all, or it might print a lot of errors to the console, 2745 especially if you are using gpm. 2746 2747config APM_ALLOW_INTS 2748 bool "Allow interrupts during APM BIOS calls" 2749 help 2750 Normally we disable external interrupts while we are making calls to 2751 the APM BIOS as a measure to lessen the effects of a badly behaving 2752 BIOS implementation. The BIOS should reenable interrupts if it 2753 needs to. Unfortunately, some BIOSes do not -- especially those in 2754 many of the newer IBM Thinkpads. If you experience hangs when you 2755 suspend, try setting this to Y. Otherwise, say N. 2756 2757endif # APM 2758 2759source "drivers/cpufreq/Kconfig" 2760 2761source "drivers/cpuidle/Kconfig" 2762 2763source "drivers/idle/Kconfig" 2764 2765endmenu 2766 2767menu "Bus options (PCI etc.)" 2768 2769choice 2770 prompt "PCI access mode" 2771 depends on X86_32 && PCI 2772 default PCI_GOANY 2773 help 2774 On PCI systems, the BIOS can be used to detect the PCI devices and 2775 determine their configuration. However, some old PCI motherboards 2776 have BIOS bugs and may crash if this is done. Also, some embedded 2777 PCI-based systems don't have any BIOS at all. Linux can also try to 2778 detect the PCI hardware directly without using the BIOS. 2779 2780 With this option, you can specify how Linux should detect the 2781 PCI devices. If you choose "BIOS", the BIOS will be used, 2782 if you choose "Direct", the BIOS won't be used, and if you 2783 choose "MMConfig", then PCI Express MMCONFIG will be used. 2784 If you choose "Any", the kernel will try MMCONFIG, then the 2785 direct access method and falls back to the BIOS if that doesn't 2786 work. If unsure, go with the default, which is "Any". 2787 2788config PCI_GOBIOS 2789 bool "BIOS" 2790 2791config PCI_GOMMCONFIG 2792 bool "MMConfig" 2793 2794config PCI_GODIRECT 2795 bool "Direct" 2796 2797config PCI_GOOLPC 2798 bool "OLPC XO-1" 2799 depends on OLPC 2800 2801config PCI_GOANY 2802 bool "Any" 2803 2804endchoice 2805 2806config PCI_BIOS 2807 def_bool y 2808 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2809 2810# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2811config PCI_DIRECT 2812 def_bool y 2813 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2814 2815config PCI_MMCONFIG 2816 bool "Support mmconfig PCI config space access" if X86_64 2817 default y 2818 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2819 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2820 2821config PCI_OLPC 2822 def_bool y 2823 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2824 2825config PCI_XEN 2826 def_bool y 2827 depends on PCI && XEN 2828 2829config MMCONF_FAM10H 2830 def_bool y 2831 depends on X86_64 && PCI_MMCONFIG && ACPI 2832 2833config PCI_CNB20LE_QUIRK 2834 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2835 depends on PCI 2836 help 2837 Read the PCI windows out of the CNB20LE host bridge. This allows 2838 PCI hotplug to work on systems with the CNB20LE chipset which do 2839 not have ACPI. 2840 2841 There's no public spec for this chipset, and this functionality 2842 is known to be incomplete. 2843 2844 You should say N unless you know you need this. 2845 2846config ISA_BUS 2847 bool "ISA bus support on modern systems" if EXPERT 2848 help 2849 Expose ISA bus device drivers and options available for selection and 2850 configuration. Enable this option if your target machine has an ISA 2851 bus. ISA is an older system, displaced by PCI and newer bus 2852 architectures -- if your target machine is modern, it probably does 2853 not have an ISA bus. 2854 2855 If unsure, say N. 2856 2857# x86_64 have no ISA slots, but can have ISA-style DMA. 2858config ISA_DMA_API 2859 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2860 default y 2861 help 2862 Enables ISA-style DMA support for devices requiring such controllers. 2863 If unsure, say Y. 2864 2865if X86_32 2866 2867config ISA 2868 bool "ISA support" 2869 help 2870 Find out whether you have ISA slots on your motherboard. ISA is the 2871 name of a bus system, i.e. the way the CPU talks to the other stuff 2872 inside your box. Other bus systems are PCI, EISA, MicroChannel 2873 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2874 newer boards don't support it. If you have ISA, say Y, otherwise N. 2875 2876config SCx200 2877 tristate "NatSemi SCx200 support" 2878 help 2879 This provides basic support for National Semiconductor's 2880 (now AMD's) Geode processors. The driver probes for the 2881 PCI-IDs of several on-chip devices, so its a good dependency 2882 for other scx200_* drivers. 2883 2884 If compiled as a module, the driver is named scx200. 2885 2886config SCx200HR_TIMER 2887 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2888 depends on SCx200 2889 default y 2890 help 2891 This driver provides a clocksource built upon the on-chip 2892 27MHz high-resolution timer. Its also a workaround for 2893 NSC Geode SC-1100's buggy TSC, which loses time when the 2894 processor goes idle (as is done by the scheduler). The 2895 other workaround is idle=poll boot option. 2896 2897config OLPC 2898 bool "One Laptop Per Child support" 2899 depends on !X86_PAE 2900 select GPIOLIB 2901 select OF 2902 select OF_PROMTREE 2903 select IRQ_DOMAIN 2904 select OLPC_EC 2905 help 2906 Add support for detecting the unique features of the OLPC 2907 XO hardware. 2908 2909config OLPC_XO1_PM 2910 bool "OLPC XO-1 Power Management" 2911 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2912 help 2913 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2914 2915config OLPC_XO1_RTC 2916 bool "OLPC XO-1 Real Time Clock" 2917 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2918 help 2919 Add support for the XO-1 real time clock, which can be used as a 2920 programmable wakeup source. 2921 2922config OLPC_XO1_SCI 2923 bool "OLPC XO-1 SCI extras" 2924 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2925 depends on INPUT=y 2926 select POWER_SUPPLY 2927 help 2928 Add support for SCI-based features of the OLPC XO-1 laptop: 2929 - EC-driven system wakeups 2930 - Power button 2931 - Ebook switch 2932 - Lid switch 2933 - AC adapter status updates 2934 - Battery status updates 2935 2936config OLPC_XO15_SCI 2937 bool "OLPC XO-1.5 SCI extras" 2938 depends on OLPC && ACPI 2939 select POWER_SUPPLY 2940 help 2941 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2942 - EC-driven system wakeups 2943 - AC adapter status updates 2944 - Battery status updates 2945 2946config ALIX 2947 bool "PCEngines ALIX System Support (LED setup)" 2948 select GPIOLIB 2949 help 2950 This option enables system support for the PCEngines ALIX. 2951 At present this just sets up LEDs for GPIO control on 2952 ALIX2/3/6 boards. However, other system specific setup should 2953 get added here. 2954 2955 Note: You must still enable the drivers for GPIO and LED support 2956 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2957 2958 Note: You have to set alix.force=1 for boards with Award BIOS. 2959 2960config NET5501 2961 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2962 select GPIOLIB 2963 help 2964 This option enables system support for the Soekris Engineering net5501. 2965 2966config GEOS 2967 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2968 select GPIOLIB 2969 depends on DMI 2970 help 2971 This option enables system support for the Traverse Technologies GEOS. 2972 2973config TS5500 2974 bool "Technologic Systems TS-5500 platform support" 2975 depends on MELAN 2976 select CHECK_SIGNATURE 2977 select NEW_LEDS 2978 select LEDS_CLASS 2979 help 2980 This option enables system support for the Technologic Systems TS-5500. 2981 2982endif # X86_32 2983 2984config AMD_NB 2985 def_bool y 2986 depends on CPU_SUP_AMD && PCI 2987 2988endmenu 2989 2990menu "Binary Emulations" 2991 2992config IA32_EMULATION 2993 bool "IA32 Emulation" 2994 depends on X86_64 2995 select ARCH_WANT_OLD_COMPAT_IPC 2996 select BINFMT_ELF 2997 select COMPAT_OLD_SIGACTION 2998 help 2999 Include code to run legacy 32-bit programs under a 3000 64-bit kernel. You should likely turn this on, unless you're 3001 100% sure that you don't have any 32-bit programs left. 3002 3003config IA32_EMULATION_DEFAULT_DISABLED 3004 bool "IA32 emulation disabled by default" 3005 default n 3006 depends on IA32_EMULATION 3007 help 3008 Make IA32 emulation disabled by default. This prevents loading 32-bit 3009 processes and access to 32-bit syscalls. If unsure, leave it to its 3010 default value. 3011 3012config X86_X32_ABI 3013 bool "x32 ABI for 64-bit mode" 3014 depends on X86_64 3015 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3016 # compressed debug sections to x86_x32 properly: 3017 # https://github.com/ClangBuiltLinux/linux/issues/514 3018 # https://github.com/ClangBuiltLinux/linux/issues/1141 3019 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3020 help 3021 Include code to run binaries for the x32 native 32-bit ABI 3022 for 64-bit processors. An x32 process gets access to the 3023 full 64-bit register file and wide data path while leaving 3024 pointers at 32 bits for smaller memory footprint. 3025 3026config COMPAT_32 3027 def_bool y 3028 depends on IA32_EMULATION || X86_32 3029 select HAVE_UID16 3030 select OLD_SIGSUSPEND3 3031 3032config COMPAT 3033 def_bool y 3034 depends on IA32_EMULATION || X86_X32_ABI 3035 3036config COMPAT_FOR_U64_ALIGNMENT 3037 def_bool y 3038 depends on COMPAT 3039 3040endmenu 3041 3042config HAVE_ATOMIC_IOMAP 3043 def_bool y 3044 depends on X86_32 3045 3046source "arch/x86/kvm/Kconfig" 3047 3048source "arch/x86/Kconfig.assembler" 3049