1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select ARCH_USE_CMPXCHG_LOCKREF 32 select HAVE_ARCH_SOFT_DIRTY 33 select MODULES_USE_ELF_RELA 34 select NEED_DMA_MAP_STATE 35 select SWIOTLB 36 select ARCH_HAS_ELFCORE_COMPAT 37 select ZONE_DMA32 38 39config FORCE_DYNAMIC_FTRACE 40 def_bool y 41 depends on X86_32 42 depends on FUNCTION_TRACER 43 select DYNAMIC_FTRACE 44 help 45 We keep the static function tracing (!DYNAMIC_FTRACE) around 46 in order to test the non static function tracing in the 47 generic code, as other architectures still use it. But we 48 only need to keep it around for x86_64. No need to keep it 49 for x86_32. For x86_32, force DYNAMIC_FTRACE. 50# 51# Arch settings 52# 53# ( Note that options that are marked 'if X86_64' could in principle be 54# ported to 32-bit as well. ) 55# 56config X86 57 def_bool y 58 # 59 # Note: keep this list sorted alphabetically 60 # 61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 63 select ARCH_32BIT_OFF_T if X86_32 64 select ARCH_CLOCKSOURCE_INIT 65 select ARCH_CONFIGURES_CPU_MITIGATIONS 66 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 67 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 68 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 69 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 70 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 71 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 72 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 73 select ARCH_HAS_CACHE_LINE_SIZE 74 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 75 select ARCH_HAS_CPU_FINALIZE_INIT 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_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 94 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 95 select ARCH_HAS_COPY_MC if X86_64 96 select ARCH_HAS_SET_MEMORY 97 select ARCH_HAS_SET_DIRECT_MAP 98 select ARCH_HAS_STRICT_KERNEL_RWX 99 select ARCH_HAS_STRICT_MODULE_RWX 100 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 101 select ARCH_HAS_SYSCALL_WRAPPER 102 select ARCH_HAS_UBSAN_SANITIZE_ALL 103 select ARCH_HAS_DEBUG_WX 104 select ARCH_HAS_ZONE_DMA_SET if EXPERT 105 select ARCH_HAVE_NMI_SAFE_CMPXCHG 106 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 107 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 108 select ARCH_MIGHT_HAVE_PC_PARPORT 109 select ARCH_MIGHT_HAVE_PC_SERIO 110 select ARCH_STACKWALK 111 select ARCH_SUPPORTS_ACPI 112 select ARCH_SUPPORTS_ATOMIC_RMW 113 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 114 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 115 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 116 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 117 select ARCH_SUPPORTS_CFI_CLANG if X86_64 118 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 119 select ARCH_SUPPORTS_LTO_CLANG 120 select ARCH_SUPPORTS_LTO_CLANG_THIN 121 select ARCH_USE_BUILTIN_BSWAP 122 select ARCH_USE_MEMTEST 123 select ARCH_USE_QUEUED_RWLOCKS 124 select ARCH_USE_QUEUED_SPINLOCKS 125 select ARCH_USE_SYM_ANNOTATIONS 126 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 127 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 128 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 129 select ARCH_WANTS_NO_INSTR 130 select ARCH_WANT_GENERAL_HUGETLB 131 select ARCH_WANT_HUGE_PMD_SHARE 132 select ARCH_WANT_LD_ORPHAN_WARN 133 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 134 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 135 select ARCH_WANTS_THP_SWAP if X86_64 136 select ARCH_HAS_PARANOID_L1D_FLUSH 137 select BUILDTIME_TABLE_SORT 138 select CLKEVT_I8253 139 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 140 select CLOCKSOURCE_WATCHDOG 141 # Word-size accesses may read uninitialized data past the trailing \0 142 # in strings and cause false KMSAN reports. 143 select DCACHE_WORD_ACCESS if !KMSAN 144 select DYNAMIC_SIGFRAME 145 select EDAC_ATOMIC_SCRUB 146 select EDAC_SUPPORT 147 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 148 select GENERIC_CLOCKEVENTS_MIN_ADJUST 149 select GENERIC_CMOS_UPDATE 150 select GENERIC_CPU_AUTOPROBE 151 select GENERIC_CPU_VULNERABILITIES 152 select GENERIC_EARLY_IOREMAP 153 select GENERIC_ENTRY 154 select GENERIC_IOMAP 155 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 156 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 157 select GENERIC_IRQ_MIGRATION if SMP 158 select GENERIC_IRQ_PROBE 159 select GENERIC_IRQ_RESERVATION_MODE 160 select GENERIC_IRQ_SHOW 161 select GENERIC_PENDING_IRQ if SMP 162 select GENERIC_PTDUMP 163 select GENERIC_SMP_IDLE_THREAD 164 select GENERIC_TIME_VSYSCALL 165 select GENERIC_GETTIMEOFDAY 166 select GENERIC_VDSO_TIME_NS 167 select GUP_GET_PXX_LOW_HIGH if X86_PAE 168 select HARDIRQS_SW_RESEND 169 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 170 select HAS_IOPORT 171 select HAVE_ACPI_APEI if ACPI 172 select HAVE_ACPI_APEI_NMI if ACPI 173 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 174 select HAVE_ARCH_AUDITSYSCALL 175 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 176 select HAVE_ARCH_HUGE_VMALLOC if X86_64 177 select HAVE_ARCH_JUMP_LABEL 178 select HAVE_ARCH_JUMP_LABEL_RELATIVE 179 select HAVE_ARCH_KASAN if X86_64 180 select HAVE_ARCH_KASAN_VMALLOC if X86_64 181 select HAVE_ARCH_KFENCE 182 select HAVE_ARCH_KMSAN if X86_64 183 select HAVE_ARCH_KGDB 184 select HAVE_ARCH_MMAP_RND_BITS if MMU 185 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 186 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 187 select HAVE_ARCH_PREL32_RELOCATIONS 188 select HAVE_ARCH_SECCOMP_FILTER 189 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 190 select HAVE_ARCH_STACKLEAK 191 select HAVE_ARCH_TRACEHOOK 192 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 193 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 194 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 195 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 196 select HAVE_ARCH_VMAP_STACK if X86_64 197 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 198 select HAVE_ARCH_WITHIN_STACK_FRAMES 199 select HAVE_ASM_MODVERSIONS 200 select HAVE_CMPXCHG_DOUBLE 201 select HAVE_CMPXCHG_LOCAL 202 select HAVE_CONTEXT_TRACKING_USER if X86_64 203 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 204 select HAVE_C_RECORDMCOUNT 205 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 206 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 207 select HAVE_BUILDTIME_MCOUNT_SORT 208 select HAVE_DEBUG_KMEMLEAK 209 select HAVE_DMA_CONTIGUOUS 210 select HAVE_DYNAMIC_FTRACE 211 select HAVE_DYNAMIC_FTRACE_WITH_REGS 212 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 213 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 214 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 215 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 216 select HAVE_EBPF_JIT 217 select HAVE_EFFICIENT_UNALIGNED_ACCESS 218 select HAVE_EISA 219 select HAVE_EXIT_THREAD 220 select HAVE_FAST_GUP 221 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 222 select HAVE_FTRACE_MCOUNT_RECORD 223 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 224 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 225 select HAVE_FUNCTION_TRACER 226 select HAVE_GCC_PLUGINS 227 select HAVE_HW_BREAKPOINT 228 select HAVE_IOREMAP_PROT 229 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 230 select HAVE_IRQ_TIME_ACCOUNTING 231 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 232 select HAVE_KERNEL_BZIP2 233 select HAVE_KERNEL_GZIP 234 select HAVE_KERNEL_LZ4 235 select HAVE_KERNEL_LZMA 236 select HAVE_KERNEL_LZO 237 select HAVE_KERNEL_XZ 238 select HAVE_KERNEL_ZSTD 239 select HAVE_KPROBES 240 select HAVE_KPROBES_ON_FTRACE 241 select HAVE_FUNCTION_ERROR_INJECTION 242 select HAVE_KRETPROBES 243 select HAVE_RETHOOK 244 select HAVE_KVM 245 select HAVE_LIVEPATCH if X86_64 246 select HAVE_MIXED_BREAKPOINTS_REGS 247 select HAVE_MOD_ARCH_SPECIFIC 248 select HAVE_MOVE_PMD 249 select HAVE_MOVE_PUD 250 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 251 select HAVE_NMI 252 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 253 select HAVE_OBJTOOL if X86_64 254 select HAVE_OPTPROBES 255 select HAVE_PCSPKR_PLATFORM 256 select HAVE_PERF_EVENTS 257 select HAVE_PERF_EVENTS_NMI 258 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 259 select HAVE_PCI 260 select HAVE_PERF_REGS 261 select HAVE_PERF_USER_STACK_DUMP 262 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 263 select MMU_GATHER_MERGE_VMAS 264 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 265 select HAVE_REGS_AND_STACK_ACCESS_API 266 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 267 select HAVE_FUNCTION_ARG_ACCESS_API 268 select HAVE_SETUP_PER_CPU_AREA 269 select HAVE_SOFTIRQ_ON_OWN_STACK 270 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 271 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 272 select HAVE_STATIC_CALL 273 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 274 select HAVE_PREEMPT_DYNAMIC_CALL 275 select HAVE_RSEQ 276 select HAVE_RUST if X86_64 277 select HAVE_SYSCALL_TRACEPOINTS 278 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 279 select HAVE_UNSTABLE_SCHED_CLOCK 280 select HAVE_USER_RETURN_NOTIFIER 281 select HAVE_GENERIC_VDSO 282 select HOTPLUG_PARALLEL if SMP && X86_64 283 select HOTPLUG_SMT if SMP 284 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 285 select IRQ_FORCED_THREADING 286 select LOCK_MM_AND_FIND_VMA 287 select NEED_PER_CPU_EMBED_FIRST_CHUNK 288 select NEED_PER_CPU_PAGE_FIRST_CHUNK 289 select NEED_SG_DMA_LENGTH 290 select PCI_DOMAINS if PCI 291 select PCI_LOCKLESS_CONFIG if PCI 292 select PERF_EVENTS 293 select RTC_LIB 294 select RTC_MC146818_LIB 295 select SPARSE_IRQ 296 select SYSCTL_EXCEPTION_TRACE 297 select THREAD_INFO_IN_TASK 298 select TRACE_IRQFLAGS_SUPPORT 299 select TRACE_IRQFLAGS_NMI_SUPPORT 300 select USER_STACKTRACE_SUPPORT 301 select HAVE_ARCH_KCSAN if X86_64 302 select PROC_PID_ARCH_STATUS if PROC_FS 303 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 304 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 305 select FUNCTION_ALIGNMENT_4B 306 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 307 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 308 309config INSTRUCTION_DECODER 310 def_bool y 311 depends on KPROBES || PERF_EVENTS || UPROBES 312 313config OUTPUT_FORMAT 314 string 315 default "elf32-i386" if X86_32 316 default "elf64-x86-64" if X86_64 317 318config LOCKDEP_SUPPORT 319 def_bool y 320 321config STACKTRACE_SUPPORT 322 def_bool y 323 324config MMU 325 def_bool y 326 327config ARCH_MMAP_RND_BITS_MIN 328 default 28 if 64BIT 329 default 8 330 331config ARCH_MMAP_RND_BITS_MAX 332 default 32 if 64BIT 333 default 16 334 335config ARCH_MMAP_RND_COMPAT_BITS_MIN 336 default 8 337 338config ARCH_MMAP_RND_COMPAT_BITS_MAX 339 default 16 340 341config SBUS 342 bool 343 344config GENERIC_ISA_DMA 345 def_bool y 346 depends on ISA_DMA_API 347 348config GENERIC_CSUM 349 bool 350 default y if KMSAN || KASAN 351 352config GENERIC_BUG 353 def_bool y 354 depends on BUG 355 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 356 357config GENERIC_BUG_RELATIVE_POINTERS 358 bool 359 360config ARCH_MAY_HAVE_PC_FDC 361 def_bool y 362 depends on ISA_DMA_API 363 364config GENERIC_CALIBRATE_DELAY 365 def_bool y 366 367config ARCH_HAS_CPU_RELAX 368 def_bool y 369 370config ARCH_HIBERNATION_POSSIBLE 371 def_bool y 372 373config ARCH_SUSPEND_POSSIBLE 374 def_bool y 375 376config AUDIT_ARCH 377 def_bool y if X86_64 378 379config KASAN_SHADOW_OFFSET 380 hex 381 depends on KASAN 382 default 0xdffffc0000000000 383 384config HAVE_INTEL_TXT 385 def_bool y 386 depends on INTEL_IOMMU && ACPI 387 388config X86_32_SMP 389 def_bool y 390 depends on X86_32 && SMP 391 392config X86_64_SMP 393 def_bool y 394 depends on X86_64 && SMP 395 396config ARCH_SUPPORTS_UPROBES 397 def_bool y 398 399config FIX_EARLYCON_MEM 400 def_bool y 401 402config DYNAMIC_PHYSICAL_MASK 403 bool 404 405config PGTABLE_LEVELS 406 int 407 default 5 if X86_5LEVEL 408 default 4 if X86_64 409 default 3 if X86_PAE 410 default 2 411 412config CC_HAS_SANE_STACKPROTECTOR 413 bool 414 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 415 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 416 help 417 We have to make sure stack protector is unconditionally disabled if 418 the compiler produces broken code or if it does not let us control 419 the segment on 32-bit kernels. 420 421menu "Processor type and features" 422 423config SMP 424 bool "Symmetric multi-processing support" 425 help 426 This enables support for systems with more than one CPU. If you have 427 a system with only one CPU, say N. If you have a system with more 428 than one CPU, say Y. 429 430 If you say N here, the kernel will run on uni- and multiprocessor 431 machines, but will use only one CPU of a multiprocessor machine. If 432 you say Y here, the kernel will run on many, but not all, 433 uniprocessor machines. On a uniprocessor machine, the kernel 434 will run faster if you say N here. 435 436 Note that if you say Y here and choose architecture "586" or 437 "Pentium" under "Processor family", the kernel will not work on 486 438 architectures. Similarly, multiprocessor kernels for the "PPro" 439 architecture may not work on all Pentium based boards. 440 441 People using multiprocessor machines who say Y here should also say 442 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 443 Management" code will be disabled if you say Y here. 444 445 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 446 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 447 <http://www.tldp.org/docs.html#howto>. 448 449 If you don't know what to do here, say N. 450 451config X86_X2APIC 452 bool "Support x2apic" 453 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 454 help 455 This enables x2apic support on CPUs that have this feature. 456 457 This allows 32-bit apic IDs (so it can support very large systems), 458 and accesses the local apic via MSRs not via mmio. 459 460 Some Intel systems circa 2022 and later are locked into x2APIC mode 461 and can not fall back to the legacy APIC modes if SGX or TDX are 462 enabled in the BIOS. They will boot with very reduced functionality 463 without enabling this option. 464 465 If you don't know what to do here, say N. 466 467config X86_MPPARSE 468 bool "Enable MPS table" if ACPI 469 default y 470 depends on X86_LOCAL_APIC 471 help 472 For old smp systems that do not have proper acpi support. Newer systems 473 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 474 475config GOLDFISH 476 def_bool y 477 depends on X86_GOLDFISH 478 479config X86_CPU_RESCTRL 480 bool "x86 CPU resource control support" 481 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 482 select KERNFS 483 select PROC_CPU_RESCTRL if PROC_FS 484 help 485 Enable x86 CPU resource control support. 486 487 Provide support for the allocation and monitoring of system resources 488 usage by the CPU. 489 490 Intel calls this Intel Resource Director Technology 491 (Intel(R) RDT). More information about RDT can be found in the 492 Intel x86 Architecture Software Developer Manual. 493 494 AMD calls this AMD Platform Quality of Service (AMD QoS). 495 More information about AMD QoS can be found in the AMD64 Technology 496 Platform Quality of Service Extensions manual. 497 498 Say N if unsure. 499 500if X86_32 501config X86_BIGSMP 502 bool "Support for big SMP systems with more than 8 CPUs" 503 depends on SMP 504 help 505 This option is needed for the systems that have more than 8 CPUs. 506 507config X86_EXTENDED_PLATFORM 508 bool "Support for extended (non-PC) x86 platforms" 509 default y 510 help 511 If you disable this option then the kernel will only support 512 standard PC platforms. (which covers the vast majority of 513 systems out there.) 514 515 If you enable this option then you'll be able to select support 516 for the following (non-PC) 32 bit x86 platforms: 517 Goldfish (Android emulator) 518 AMD Elan 519 RDC R-321x SoC 520 SGI 320/540 (Visual Workstation) 521 STA2X11-based (e.g. Northville) 522 Moorestown MID devices 523 524 If you have one of these systems, or if you want to build a 525 generic distribution kernel, say Y here - otherwise say N. 526endif # X86_32 527 528if X86_64 529config X86_EXTENDED_PLATFORM 530 bool "Support for extended (non-PC) x86 platforms" 531 default y 532 help 533 If you disable this option then the kernel will only support 534 standard PC platforms. (which covers the vast majority of 535 systems out there.) 536 537 If you enable this option then you'll be able to select support 538 for the following (non-PC) 64 bit x86 platforms: 539 Numascale NumaChip 540 ScaleMP vSMP 541 SGI Ultraviolet 542 543 If you have one of these systems, or if you want to build a 544 generic distribution kernel, say Y here - otherwise say N. 545endif # X86_64 546# This is an alphabetically sorted list of 64 bit extended platforms 547# Please maintain the alphabetic order if and when there are additions 548config X86_NUMACHIP 549 bool "Numascale NumaChip" 550 depends on X86_64 551 depends on X86_EXTENDED_PLATFORM 552 depends on NUMA 553 depends on SMP 554 depends on X86_X2APIC 555 depends on PCI_MMCONFIG 556 help 557 Adds support for Numascale NumaChip large-SMP systems. Needed to 558 enable more than ~168 cores. 559 If you don't have one of these, you should say N here. 560 561config X86_VSMP 562 bool "ScaleMP vSMP" 563 select HYPERVISOR_GUEST 564 select PARAVIRT 565 depends on X86_64 && PCI 566 depends on X86_EXTENDED_PLATFORM 567 depends on SMP 568 help 569 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 570 supposed to run on these EM64T-based machines. Only choose this option 571 if you have one of these machines. 572 573config X86_UV 574 bool "SGI Ultraviolet" 575 depends on X86_64 576 depends on X86_EXTENDED_PLATFORM 577 depends on NUMA 578 depends on EFI 579 depends on KEXEC_CORE 580 depends on X86_X2APIC 581 depends on PCI 582 help 583 This option is needed in order to support SGI Ultraviolet systems. 584 If you don't have one of these, you should say N here. 585 586# Following is an alphabetically sorted list of 32 bit extended platforms 587# Please maintain the alphabetic order if and when there are additions 588 589config X86_GOLDFISH 590 bool "Goldfish (Virtual Platform)" 591 depends on X86_EXTENDED_PLATFORM 592 help 593 Enable support for the Goldfish virtual platform used primarily 594 for Android development. Unless you are building for the Android 595 Goldfish emulator say N here. 596 597config X86_INTEL_CE 598 bool "CE4100 TV platform" 599 depends on PCI 600 depends on PCI_GODIRECT 601 depends on X86_IO_APIC 602 depends on X86_32 603 depends on X86_EXTENDED_PLATFORM 604 select X86_REBOOTFIXUPS 605 select OF 606 select OF_EARLY_FLATTREE 607 help 608 Select for the Intel CE media processor (CE4100) SOC. 609 This option compiles in support for the CE4100 SOC for settop 610 boxes and media devices. 611 612config X86_INTEL_MID 613 bool "Intel MID platform support" 614 depends on X86_EXTENDED_PLATFORM 615 depends on X86_PLATFORM_DEVICES 616 depends on PCI 617 depends on X86_64 || (PCI_GOANY && X86_32) 618 depends on X86_IO_APIC 619 select I2C 620 select DW_APB_TIMER 621 select INTEL_SCU_PCI 622 help 623 Select to build a kernel capable of supporting Intel MID (Mobile 624 Internet Device) platform systems which do not have the PCI legacy 625 interfaces. If you are building for a PC class system say N here. 626 627 Intel MID platforms are based on an Intel processor and chipset which 628 consume less power than most of the x86 derivatives. 629 630config X86_INTEL_QUARK 631 bool "Intel Quark platform support" 632 depends on X86_32 633 depends on X86_EXTENDED_PLATFORM 634 depends on X86_PLATFORM_DEVICES 635 depends on X86_TSC 636 depends on PCI 637 depends on PCI_GOANY 638 depends on X86_IO_APIC 639 select IOSF_MBI 640 select INTEL_IMR 641 select COMMON_CLK 642 help 643 Select to include support for Quark X1000 SoC. 644 Say Y here if you have a Quark based system such as the Arduino 645 compatible Intel Galileo. 646 647config X86_INTEL_LPSS 648 bool "Intel Low Power Subsystem Support" 649 depends on X86 && ACPI && PCI 650 select COMMON_CLK 651 select PINCTRL 652 select IOSF_MBI 653 help 654 Select to build support for Intel Low Power Subsystem such as 655 found on Intel Lynxpoint PCH. Selecting this option enables 656 things like clock tree (common clock framework) and pincontrol 657 which are needed by the LPSS peripheral drivers. 658 659config X86_AMD_PLATFORM_DEVICE 660 bool "AMD ACPI2Platform devices support" 661 depends on ACPI 662 select COMMON_CLK 663 select PINCTRL 664 help 665 Select to interpret AMD specific ACPI device to platform device 666 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 667 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 668 implemented under PINCTRL subsystem. 669 670config IOSF_MBI 671 tristate "Intel SoC IOSF Sideband support for SoC platforms" 672 depends on PCI 673 help 674 This option enables sideband register access support for Intel SoC 675 platforms. On these platforms the IOSF sideband is used in lieu of 676 MSR's for some register accesses, mostly but not limited to thermal 677 and power. Drivers may query the availability of this device to 678 determine if they need the sideband in order to work on these 679 platforms. The sideband is available on the following SoC products. 680 This list is not meant to be exclusive. 681 - BayTrail 682 - Braswell 683 - Quark 684 685 You should say Y if you are running a kernel on one of these SoC's. 686 687config IOSF_MBI_DEBUG 688 bool "Enable IOSF sideband access through debugfs" 689 depends on IOSF_MBI && DEBUG_FS 690 help 691 Select this option to expose the IOSF sideband access registers (MCR, 692 MDR, MCRX) through debugfs to write and read register information from 693 different units on the SoC. This is most useful for obtaining device 694 state information for debug and analysis. As this is a general access 695 mechanism, users of this option would have specific knowledge of the 696 device they want to access. 697 698 If you don't require the option or are in doubt, say N. 699 700config X86_RDC321X 701 bool "RDC R-321x SoC" 702 depends on X86_32 703 depends on X86_EXTENDED_PLATFORM 704 select M486 705 select X86_REBOOTFIXUPS 706 help 707 This option is needed for RDC R-321x system-on-chip, also known 708 as R-8610-(G). 709 If you don't have one of these chips, you should say N here. 710 711config X86_32_NON_STANDARD 712 bool "Support non-standard 32-bit SMP architectures" 713 depends on X86_32 && SMP 714 depends on X86_EXTENDED_PLATFORM 715 help 716 This option compiles in the bigsmp and STA2X11 default 717 subarchitectures. It is intended for a generic binary 718 kernel. If you select them all, kernel will probe it one by 719 one and will fallback to default. 720 721# Alphabetically sorted list of Non standard 32 bit platforms 722 723config X86_SUPPORTS_MEMORY_FAILURE 724 def_bool y 725 # MCE code calls memory_failure(): 726 depends on X86_MCE 727 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 728 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 729 depends on X86_64 || !SPARSEMEM 730 select ARCH_SUPPORTS_MEMORY_FAILURE 731 732config STA2X11 733 bool "STA2X11 Companion Chip Support" 734 depends on X86_32_NON_STANDARD && PCI 735 select SWIOTLB 736 select MFD_STA2X11 737 select GPIOLIB 738 help 739 This adds support for boards based on the STA2X11 IO-Hub, 740 a.k.a. "ConneXt". The chip is used in place of the standard 741 PC chipset, so all "standard" peripherals are missing. If this 742 option is selected the kernel will still be able to boot on 743 standard PC machines. 744 745config X86_32_IRIS 746 tristate "Eurobraille/Iris poweroff module" 747 depends on X86_32 748 help 749 The Iris machines from EuroBraille do not have APM or ACPI support 750 to shut themselves down properly. A special I/O sequence is 751 needed to do so, which is what this module does at 752 kernel shutdown. 753 754 This is only for Iris machines from EuroBraille. 755 756 If unused, say N. 757 758config SCHED_OMIT_FRAME_POINTER 759 def_bool y 760 prompt "Single-depth WCHAN output" 761 depends on X86 762 help 763 Calculate simpler /proc/<PID>/wchan values. If this option 764 is disabled then wchan values will recurse back to the 765 caller function. This provides more accurate wchan values, 766 at the expense of slightly more scheduling overhead. 767 768 If in doubt, say "Y". 769 770menuconfig HYPERVISOR_GUEST 771 bool "Linux guest support" 772 help 773 Say Y here to enable options for running Linux under various hyper- 774 visors. This option enables basic hypervisor detection and platform 775 setup. 776 777 If you say N, all options in this submenu will be skipped and 778 disabled, and Linux guest support won't be built in. 779 780if HYPERVISOR_GUEST 781 782config PARAVIRT 783 bool "Enable paravirtualization code" 784 depends on HAVE_STATIC_CALL 785 help 786 This changes the kernel so it can modify itself when it is run 787 under a hypervisor, potentially improving performance significantly 788 over full virtualization. However, when run without a hypervisor 789 the kernel is theoretically slower and slightly larger. 790 791config PARAVIRT_XXL 792 bool 793 794config PARAVIRT_DEBUG 795 bool "paravirt-ops debugging" 796 depends on PARAVIRT && DEBUG_KERNEL 797 help 798 Enable to debug paravirt_ops internals. Specifically, BUG if 799 a paravirt_op is missing when it is called. 800 801config PARAVIRT_SPINLOCKS 802 bool "Paravirtualization layer for spinlocks" 803 depends on PARAVIRT && SMP 804 help 805 Paravirtualized spinlocks allow a pvops backend to replace the 806 spinlock implementation with something virtualization-friendly 807 (for example, block the virtual CPU rather than spinning). 808 809 It has a minimal impact on native kernels and gives a nice performance 810 benefit on paravirtualized KVM / Xen kernels. 811 812 If you are unsure how to answer this question, answer Y. 813 814config X86_HV_CALLBACK_VECTOR 815 def_bool n 816 817source "arch/x86/xen/Kconfig" 818 819config KVM_GUEST 820 bool "KVM Guest support (including kvmclock)" 821 depends on PARAVIRT 822 select PARAVIRT_CLOCK 823 select ARCH_CPUIDLE_HALTPOLL 824 select X86_HV_CALLBACK_VECTOR 825 default y 826 help 827 This option enables various optimizations for running under the KVM 828 hypervisor. It includes a paravirtualized clock, so that instead 829 of relying on a PIT (or probably other) emulation by the 830 underlying device model, the host provides the guest with 831 timing infrastructure such as time of day, and system time 832 833config ARCH_CPUIDLE_HALTPOLL 834 def_bool n 835 prompt "Disable host haltpoll when loading haltpoll driver" 836 help 837 If virtualized under KVM, disable host haltpoll. 838 839config PVH 840 bool "Support for running PVH guests" 841 help 842 This option enables the PVH entry point for guest virtual machines 843 as specified in the x86/HVM direct boot ABI. 844 845config PARAVIRT_TIME_ACCOUNTING 846 bool "Paravirtual steal time accounting" 847 depends on PARAVIRT 848 help 849 Select this option to enable fine granularity task steal time 850 accounting. Time spent executing other tasks in parallel with 851 the current vCPU is discounted from the vCPU power. To account for 852 that, there can be a small performance impact. 853 854 If in doubt, say N here. 855 856config PARAVIRT_CLOCK 857 bool 858 859config JAILHOUSE_GUEST 860 bool "Jailhouse non-root cell support" 861 depends on X86_64 && PCI 862 select X86_PM_TIMER 863 help 864 This option allows to run Linux as guest in a Jailhouse non-root 865 cell. You can leave this option disabled if you only want to start 866 Jailhouse and run Linux afterwards in the root cell. 867 868config ACRN_GUEST 869 bool "ACRN Guest support" 870 depends on X86_64 871 select X86_HV_CALLBACK_VECTOR 872 help 873 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 874 a flexible, lightweight reference open-source hypervisor, built with 875 real-time and safety-criticality in mind. It is built for embedded 876 IOT with small footprint and real-time features. More details can be 877 found in https://projectacrn.org/. 878 879config INTEL_TDX_GUEST 880 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 881 depends on X86_64 && CPU_SUP_INTEL 882 depends on X86_X2APIC 883 depends on EFI_STUB 884 select ARCH_HAS_CC_PLATFORM 885 select X86_MEM_ENCRYPT 886 select X86_MCE 887 select UNACCEPTED_MEMORY 888 help 889 Support running as a guest under Intel TDX. Without this support, 890 the guest kernel can not boot or run under TDX. 891 TDX includes memory encryption and integrity capabilities 892 which protect the confidentiality and integrity of guest 893 memory contents and CPU state. TDX guests are protected from 894 some attacks from the VMM. 895 896endif # HYPERVISOR_GUEST 897 898source "arch/x86/Kconfig.cpu" 899 900config HPET_TIMER 901 def_bool X86_64 902 prompt "HPET Timer Support" if X86_32 903 help 904 Use the IA-PC HPET (High Precision Event Timer) to manage 905 time in preference to the PIT and RTC, if a HPET is 906 present. 907 HPET is the next generation timer replacing legacy 8254s. 908 The HPET provides a stable time base on SMP 909 systems, unlike the TSC, but it is more expensive to access, 910 as it is off-chip. The interface used is documented 911 in the HPET spec, revision 1. 912 913 You can safely choose Y here. However, HPET will only be 914 activated if the platform and the BIOS support this feature. 915 Otherwise the 8254 will be used for timing services. 916 917 Choose N to continue using the legacy 8254 timer. 918 919config HPET_EMULATE_RTC 920 def_bool y 921 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 922 923# Mark as expert because too many people got it wrong. 924# The code disables itself when not needed. 925config DMI 926 default y 927 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 928 bool "Enable DMI scanning" if EXPERT 929 help 930 Enabled scanning of DMI to identify machine quirks. Say Y 931 here unless you have verified that your setup is not 932 affected by entries in the DMI blacklist. Required by PNP 933 BIOS code. 934 935config GART_IOMMU 936 bool "Old AMD GART IOMMU support" 937 select DMA_OPS 938 select IOMMU_HELPER 939 select SWIOTLB 940 depends on X86_64 && PCI && AMD_NB 941 help 942 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 943 GART based hardware IOMMUs. 944 945 The GART supports full DMA access for devices with 32-bit access 946 limitations, on systems with more than 3 GB. This is usually needed 947 for USB, sound, many IDE/SATA chipsets and some other devices. 948 949 Newer systems typically have a modern AMD IOMMU, supported via 950 the CONFIG_AMD_IOMMU=y config option. 951 952 In normal configurations this driver is only active when needed: 953 there's more than 3 GB of memory and the system contains a 954 32-bit limited device. 955 956 If unsure, say Y. 957 958config BOOT_VESA_SUPPORT 959 bool 960 help 961 If true, at least one selected framebuffer driver can take advantage 962 of VESA video modes set at an early boot stage via the vga= parameter. 963 964config MAXSMP 965 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 966 depends on X86_64 && SMP && DEBUG_KERNEL 967 select CPUMASK_OFFSTACK 968 help 969 Enable maximum number of CPUS and NUMA Nodes for this architecture. 970 If unsure, say N. 971 972# 973# The maximum number of CPUs supported: 974# 975# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 976# and which can be configured interactively in the 977# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 978# 979# The ranges are different on 32-bit and 64-bit kernels, depending on 980# hardware capabilities and scalability features of the kernel. 981# 982# ( If MAXSMP is enabled we just use the highest possible value and disable 983# interactive configuration. ) 984# 985 986config NR_CPUS_RANGE_BEGIN 987 int 988 default NR_CPUS_RANGE_END if MAXSMP 989 default 1 if !SMP 990 default 2 991 992config NR_CPUS_RANGE_END 993 int 994 depends on X86_32 995 default 64 if SMP && X86_BIGSMP 996 default 8 if SMP && !X86_BIGSMP 997 default 1 if !SMP 998 999config NR_CPUS_RANGE_END 1000 int 1001 depends on X86_64 1002 default 8192 if SMP && CPUMASK_OFFSTACK 1003 default 512 if SMP && !CPUMASK_OFFSTACK 1004 default 1 if !SMP 1005 1006config NR_CPUS_DEFAULT 1007 int 1008 depends on X86_32 1009 default 32 if X86_BIGSMP 1010 default 8 if SMP 1011 default 1 if !SMP 1012 1013config NR_CPUS_DEFAULT 1014 int 1015 depends on X86_64 1016 default 8192 if MAXSMP 1017 default 64 if SMP 1018 default 1 if !SMP 1019 1020config NR_CPUS 1021 int "Maximum number of CPUs" if SMP && !MAXSMP 1022 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1023 default NR_CPUS_DEFAULT 1024 help 1025 This allows you to specify the maximum number of CPUs which this 1026 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1027 supported value is 8192, otherwise the maximum value is 512. The 1028 minimum value which makes sense is 2. 1029 1030 This is purely to save memory: each supported CPU adds about 8KB 1031 to the kernel image. 1032 1033config SCHED_CLUSTER 1034 bool "Cluster scheduler support" 1035 depends on SMP 1036 default y 1037 help 1038 Cluster scheduler support improves the CPU scheduler's decision 1039 making when dealing with machines that have clusters of CPUs. 1040 Cluster usually means a couple of CPUs which are placed closely 1041 by sharing mid-level caches, last-level cache tags or internal 1042 busses. 1043 1044config SCHED_SMT 1045 def_bool y if SMP 1046 1047config SCHED_MC 1048 def_bool y 1049 prompt "Multi-core scheduler support" 1050 depends on SMP 1051 help 1052 Multi-core scheduler support improves the CPU scheduler's decision 1053 making when dealing with multi-core CPU chips at a cost of slightly 1054 increased overhead in some places. If unsure say N here. 1055 1056config SCHED_MC_PRIO 1057 bool "CPU core priorities scheduler support" 1058 depends on SCHED_MC && CPU_SUP_INTEL 1059 select X86_INTEL_PSTATE 1060 select CPU_FREQ 1061 default y 1062 help 1063 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1064 core ordering determined at manufacturing time, which allows 1065 certain cores to reach higher turbo frequencies (when running 1066 single threaded workloads) than others. 1067 1068 Enabling this kernel feature teaches the scheduler about 1069 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1070 scheduler's CPU selection logic accordingly, so that higher 1071 overall system performance can be achieved. 1072 1073 This feature will have no effect on CPUs without this feature. 1074 1075 If unsure say Y here. 1076 1077config UP_LATE_INIT 1078 def_bool y 1079 depends on !SMP && X86_LOCAL_APIC 1080 1081config X86_UP_APIC 1082 bool "Local APIC support on uniprocessors" if !PCI_MSI 1083 default PCI_MSI 1084 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1085 help 1086 A local APIC (Advanced Programmable Interrupt Controller) is an 1087 integrated interrupt controller in the CPU. If you have a single-CPU 1088 system which has a processor with a local APIC, you can say Y here to 1089 enable and use it. If you say Y here even though your machine doesn't 1090 have a local APIC, then the kernel will still run with no slowdown at 1091 all. The local APIC supports CPU-generated self-interrupts (timer, 1092 performance counters), and the NMI watchdog which detects hard 1093 lockups. 1094 1095config X86_UP_IOAPIC 1096 bool "IO-APIC support on uniprocessors" 1097 depends on X86_UP_APIC 1098 help 1099 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1100 SMP-capable replacement for PC-style interrupt controllers. Most 1101 SMP systems and many recent uniprocessor systems have one. 1102 1103 If you have a single-CPU system with an IO-APIC, you can say Y here 1104 to use it. If you say Y here even though your machine doesn't have 1105 an IO-APIC, then the kernel will still run with no slowdown at all. 1106 1107config X86_LOCAL_APIC 1108 def_bool y 1109 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1110 select IRQ_DOMAIN_HIERARCHY 1111 1112config X86_IO_APIC 1113 def_bool y 1114 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1115 1116config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1117 bool "Reroute for broken boot IRQs" 1118 depends on X86_IO_APIC 1119 help 1120 This option enables a workaround that fixes a source of 1121 spurious interrupts. This is recommended when threaded 1122 interrupt handling is used on systems where the generation of 1123 superfluous "boot interrupts" cannot be disabled. 1124 1125 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1126 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1127 kernel does during interrupt handling). On chipsets where this 1128 boot IRQ generation cannot be disabled, this workaround keeps 1129 the original IRQ line masked so that only the equivalent "boot 1130 IRQ" is delivered to the CPUs. The workaround also tells the 1131 kernel to set up the IRQ handler on the boot IRQ line. In this 1132 way only one interrupt is delivered to the kernel. Otherwise 1133 the spurious second interrupt may cause the kernel to bring 1134 down (vital) interrupt lines. 1135 1136 Only affects "broken" chipsets. Interrupt sharing may be 1137 increased on these systems. 1138 1139config X86_MCE 1140 bool "Machine Check / overheating reporting" 1141 select GENERIC_ALLOCATOR 1142 default y 1143 help 1144 Machine Check support allows the processor to notify the 1145 kernel if it detects a problem (e.g. overheating, data corruption). 1146 The action the kernel takes depends on the severity of the problem, 1147 ranging from warning messages to halting the machine. 1148 1149config X86_MCELOG_LEGACY 1150 bool "Support for deprecated /dev/mcelog character device" 1151 depends on X86_MCE 1152 help 1153 Enable support for /dev/mcelog which is needed by the old mcelog 1154 userspace logging daemon. Consider switching to the new generation 1155 rasdaemon solution. 1156 1157config X86_MCE_INTEL 1158 def_bool y 1159 prompt "Intel MCE features" 1160 depends on X86_MCE && X86_LOCAL_APIC 1161 help 1162 Additional support for intel specific MCE features such as 1163 the thermal monitor. 1164 1165config X86_MCE_AMD 1166 def_bool y 1167 prompt "AMD MCE features" 1168 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1169 help 1170 Additional support for AMD specific MCE features such as 1171 the DRAM Error Threshold. 1172 1173config X86_ANCIENT_MCE 1174 bool "Support for old Pentium 5 / WinChip machine checks" 1175 depends on X86_32 && X86_MCE 1176 help 1177 Include support for machine check handling on old Pentium 5 or WinChip 1178 systems. These typically need to be enabled explicitly on the command 1179 line. 1180 1181config X86_MCE_THRESHOLD 1182 depends on X86_MCE_AMD || X86_MCE_INTEL 1183 def_bool y 1184 1185config X86_MCE_INJECT 1186 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1187 tristate "Machine check injector support" 1188 help 1189 Provide support for injecting machine checks for testing purposes. 1190 If you don't know what a machine check is and you don't do kernel 1191 QA it is safe to say n. 1192 1193source "arch/x86/events/Kconfig" 1194 1195config X86_LEGACY_VM86 1196 bool "Legacy VM86 support" 1197 depends on X86_32 1198 help 1199 This option allows user programs to put the CPU into V8086 1200 mode, which is an 80286-era approximation of 16-bit real mode. 1201 1202 Some very old versions of X and/or vbetool require this option 1203 for user mode setting. Similarly, DOSEMU will use it if 1204 available to accelerate real mode DOS programs. However, any 1205 recent version of DOSEMU, X, or vbetool should be fully 1206 functional even without kernel VM86 support, as they will all 1207 fall back to software emulation. Nevertheless, if you are using 1208 a 16-bit DOS program where 16-bit performance matters, vm86 1209 mode might be faster than emulation and you might want to 1210 enable this option. 1211 1212 Note that any app that works on a 64-bit kernel is unlikely to 1213 need this option, as 64-bit kernels don't, and can't, support 1214 V8086 mode. This option is also unrelated to 16-bit protected 1215 mode and is not needed to run most 16-bit programs under Wine. 1216 1217 Enabling this option increases the complexity of the kernel 1218 and slows down exception handling a tiny bit. 1219 1220 If unsure, say N here. 1221 1222config VM86 1223 bool 1224 default X86_LEGACY_VM86 1225 1226config X86_16BIT 1227 bool "Enable support for 16-bit segments" if EXPERT 1228 default y 1229 depends on MODIFY_LDT_SYSCALL 1230 help 1231 This option is required by programs like Wine to run 16-bit 1232 protected mode legacy code on x86 processors. Disabling 1233 this option saves about 300 bytes on i386, or around 6K text 1234 plus 16K runtime memory on x86-64, 1235 1236config X86_ESPFIX32 1237 def_bool y 1238 depends on X86_16BIT && X86_32 1239 1240config X86_ESPFIX64 1241 def_bool y 1242 depends on X86_16BIT && X86_64 1243 1244config X86_VSYSCALL_EMULATION 1245 bool "Enable vsyscall emulation" if EXPERT 1246 default y 1247 depends on X86_64 1248 help 1249 This enables emulation of the legacy vsyscall page. Disabling 1250 it is roughly equivalent to booting with vsyscall=none, except 1251 that it will also disable the helpful warning if a program 1252 tries to use a vsyscall. With this option set to N, offending 1253 programs will just segfault, citing addresses of the form 1254 0xffffffffff600?00. 1255 1256 This option is required by many programs built before 2013, and 1257 care should be used even with newer programs if set to N. 1258 1259 Disabling this option saves about 7K of kernel size and 1260 possibly 4K of additional runtime pagetable memory. 1261 1262config X86_IOPL_IOPERM 1263 bool "IOPERM and IOPL Emulation" 1264 default y 1265 help 1266 This enables the ioperm() and iopl() syscalls which are necessary 1267 for legacy applications. 1268 1269 Legacy IOPL support is an overbroad mechanism which allows user 1270 space aside of accessing all 65536 I/O ports also to disable 1271 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1272 capabilities and permission from potentially active security 1273 modules. 1274 1275 The emulation restricts the functionality of the syscall to 1276 only allowing the full range I/O port access, but prevents the 1277 ability to disable interrupts from user space which would be 1278 granted if the hardware IOPL mechanism would be used. 1279 1280config TOSHIBA 1281 tristate "Toshiba Laptop support" 1282 depends on X86_32 1283 help 1284 This adds a driver to safely access the System Management Mode of 1285 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1286 not work on models with a Phoenix BIOS. The System Management Mode 1287 is used to set the BIOS and power saving options on Toshiba portables. 1288 1289 For information on utilities to make use of this driver see the 1290 Toshiba Linux utilities web site at: 1291 <http://www.buzzard.org.uk/toshiba/>. 1292 1293 Say Y if you intend to run this kernel on a Toshiba portable. 1294 Say N otherwise. 1295 1296config X86_REBOOTFIXUPS 1297 bool "Enable X86 board specific fixups for reboot" 1298 depends on X86_32 1299 help 1300 This enables chipset and/or board specific fixups to be done 1301 in order to get reboot to work correctly. This is only needed on 1302 some combinations of hardware and BIOS. The symptom, for which 1303 this config is intended, is when reboot ends with a stalled/hung 1304 system. 1305 1306 Currently, the only fixup is for the Geode machines using 1307 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1308 1309 Say Y if you want to enable the fixup. Currently, it's safe to 1310 enable this option even if you don't need it. 1311 Say N otherwise. 1312 1313config MICROCODE 1314 def_bool y 1315 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1316 1317config MICROCODE_LATE_LOADING 1318 bool "Late microcode loading (DANGEROUS)" 1319 default n 1320 depends on MICROCODE 1321 help 1322 Loading microcode late, when the system is up and executing instructions 1323 is a tricky business and should be avoided if possible. Just the sequence 1324 of synchronizing all cores and SMT threads is one fragile dance which does 1325 not guarantee that cores might not softlock after the loading. Therefore, 1326 use this at your own risk. Late loading taints the kernel too. 1327 1328config X86_MSR 1329 tristate "/dev/cpu/*/msr - Model-specific register support" 1330 help 1331 This device gives privileged processes access to the x86 1332 Model-Specific Registers (MSRs). It is a character device with 1333 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1334 MSR accesses are directed to a specific CPU on multi-processor 1335 systems. 1336 1337config X86_CPUID 1338 tristate "/dev/cpu/*/cpuid - CPU information support" 1339 help 1340 This device gives processes access to the x86 CPUID instruction to 1341 be executed on a specific processor. It is a character device 1342 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1343 /dev/cpu/31/cpuid. 1344 1345choice 1346 prompt "High Memory Support" 1347 default HIGHMEM4G 1348 depends on X86_32 1349 1350config NOHIGHMEM 1351 bool "off" 1352 help 1353 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1354 However, the address space of 32-bit x86 processors is only 4 1355 Gigabytes large. That means that, if you have a large amount of 1356 physical memory, not all of it can be "permanently mapped" by the 1357 kernel. The physical memory that's not permanently mapped is called 1358 "high memory". 1359 1360 If you are compiling a kernel which will never run on a machine with 1361 more than 1 Gigabyte total physical RAM, answer "off" here (default 1362 choice and suitable for most users). This will result in a "3GB/1GB" 1363 split: 3GB are mapped so that each process sees a 3GB virtual memory 1364 space and the remaining part of the 4GB virtual memory space is used 1365 by the kernel to permanently map as much physical memory as 1366 possible. 1367 1368 If the machine has between 1 and 4 Gigabytes physical RAM, then 1369 answer "4GB" here. 1370 1371 If more than 4 Gigabytes is used then answer "64GB" here. This 1372 selection turns Intel PAE (Physical Address Extension) mode on. 1373 PAE implements 3-level paging on IA32 processors. PAE is fully 1374 supported by Linux, PAE mode is implemented on all recent Intel 1375 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1376 then the kernel will not boot on CPUs that don't support PAE! 1377 1378 The actual amount of total physical memory will either be 1379 auto detected or can be forced by using a kernel command line option 1380 such as "mem=256M". (Try "man bootparam" or see the documentation of 1381 your boot loader (lilo or loadlin) about how to pass options to the 1382 kernel at boot time.) 1383 1384 If unsure, say "off". 1385 1386config HIGHMEM4G 1387 bool "4GB" 1388 help 1389 Select this if you have a 32-bit processor and between 1 and 4 1390 gigabytes of physical RAM. 1391 1392config HIGHMEM64G 1393 bool "64GB" 1394 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1395 select X86_PAE 1396 help 1397 Select this if you have a 32-bit processor and more than 4 1398 gigabytes of physical RAM. 1399 1400endchoice 1401 1402choice 1403 prompt "Memory split" if EXPERT 1404 default VMSPLIT_3G 1405 depends on X86_32 1406 help 1407 Select the desired split between kernel and user memory. 1408 1409 If the address range available to the kernel is less than the 1410 physical memory installed, the remaining memory will be available 1411 as "high memory". Accessing high memory is a little more costly 1412 than low memory, as it needs to be mapped into the kernel first. 1413 Note that increasing the kernel address space limits the range 1414 available to user programs, making the address space there 1415 tighter. Selecting anything other than the default 3G/1G split 1416 will also likely make your kernel incompatible with binary-only 1417 kernel modules. 1418 1419 If you are not absolutely sure what you are doing, leave this 1420 option alone! 1421 1422 config VMSPLIT_3G 1423 bool "3G/1G user/kernel split" 1424 config VMSPLIT_3G_OPT 1425 depends on !X86_PAE 1426 bool "3G/1G user/kernel split (for full 1G low memory)" 1427 config VMSPLIT_2G 1428 bool "2G/2G user/kernel split" 1429 config VMSPLIT_2G_OPT 1430 depends on !X86_PAE 1431 bool "2G/2G user/kernel split (for full 2G low memory)" 1432 config VMSPLIT_1G 1433 bool "1G/3G user/kernel split" 1434endchoice 1435 1436config PAGE_OFFSET 1437 hex 1438 default 0xB0000000 if VMSPLIT_3G_OPT 1439 default 0x80000000 if VMSPLIT_2G 1440 default 0x78000000 if VMSPLIT_2G_OPT 1441 default 0x40000000 if VMSPLIT_1G 1442 default 0xC0000000 1443 depends on X86_32 1444 1445config HIGHMEM 1446 def_bool y 1447 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1448 1449config X86_PAE 1450 bool "PAE (Physical Address Extension) Support" 1451 depends on X86_32 && !HIGHMEM4G 1452 select PHYS_ADDR_T_64BIT 1453 select SWIOTLB 1454 help 1455 PAE is required for NX support, and furthermore enables 1456 larger swapspace support for non-overcommit purposes. It 1457 has the cost of more pagetable lookup overhead, and also 1458 consumes more pagetable space per process. 1459 1460config X86_5LEVEL 1461 bool "Enable 5-level page tables support" 1462 default y 1463 select DYNAMIC_MEMORY_LAYOUT 1464 select SPARSEMEM_VMEMMAP 1465 depends on X86_64 1466 help 1467 5-level paging enables access to larger address space: 1468 up to 128 PiB of virtual address space and 4 PiB of 1469 physical address space. 1470 1471 It will be supported by future Intel CPUs. 1472 1473 A kernel with the option enabled can be booted on machines that 1474 support 4- or 5-level paging. 1475 1476 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1477 information. 1478 1479 Say N if unsure. 1480 1481config X86_DIRECT_GBPAGES 1482 def_bool y 1483 depends on X86_64 1484 help 1485 Certain kernel features effectively disable kernel 1486 linear 1 GB mappings (even if the CPU otherwise 1487 supports them), so don't confuse the user by printing 1488 that we have them enabled. 1489 1490config X86_CPA_STATISTICS 1491 bool "Enable statistic for Change Page Attribute" 1492 depends on DEBUG_FS 1493 help 1494 Expose statistics about the Change Page Attribute mechanism, which 1495 helps to determine the effectiveness of preserving large and huge 1496 page mappings when mapping protections are changed. 1497 1498config X86_MEM_ENCRYPT 1499 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1500 select DYNAMIC_PHYSICAL_MASK 1501 def_bool n 1502 1503config AMD_MEM_ENCRYPT 1504 bool "AMD Secure Memory Encryption (SME) support" 1505 depends on X86_64 && CPU_SUP_AMD 1506 depends on EFI_STUB 1507 select DMA_COHERENT_POOL 1508 select ARCH_USE_MEMREMAP_PROT 1509 select INSTRUCTION_DECODER 1510 select ARCH_HAS_CC_PLATFORM 1511 select X86_MEM_ENCRYPT 1512 select UNACCEPTED_MEMORY 1513 help 1514 Say yes to enable support for the encryption of system memory. 1515 This requires an AMD processor that supports Secure Memory 1516 Encryption (SME). 1517 1518# Common NUMA Features 1519config NUMA 1520 bool "NUMA Memory Allocation and Scheduler Support" 1521 depends on SMP 1522 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1523 default y if X86_BIGSMP 1524 select USE_PERCPU_NUMA_NODE_ID 1525 help 1526 Enable NUMA (Non-Uniform Memory Access) support. 1527 1528 The kernel will try to allocate memory used by a CPU on the 1529 local memory controller of the CPU and add some more 1530 NUMA awareness to the kernel. 1531 1532 For 64-bit this is recommended if the system is Intel Core i7 1533 (or later), AMD Opteron, or EM64T NUMA. 1534 1535 For 32-bit this is only needed if you boot a 32-bit 1536 kernel on a 64-bit NUMA platform. 1537 1538 Otherwise, you should say N. 1539 1540config AMD_NUMA 1541 def_bool y 1542 prompt "Old style AMD Opteron NUMA detection" 1543 depends on X86_64 && NUMA && PCI 1544 help 1545 Enable AMD NUMA node topology detection. You should say Y here if 1546 you have a multi processor AMD system. This uses an old method to 1547 read the NUMA configuration directly from the builtin Northbridge 1548 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1549 which also takes priority if both are compiled in. 1550 1551config X86_64_ACPI_NUMA 1552 def_bool y 1553 prompt "ACPI NUMA detection" 1554 depends on X86_64 && NUMA && ACPI && PCI 1555 select ACPI_NUMA 1556 help 1557 Enable ACPI SRAT based node topology detection. 1558 1559config NUMA_EMU 1560 bool "NUMA emulation" 1561 depends on NUMA 1562 help 1563 Enable NUMA emulation. A flat machine will be split 1564 into virtual nodes when booted with "numa=fake=N", where N is the 1565 number of nodes. This is only useful for debugging. 1566 1567config NODES_SHIFT 1568 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1569 range 1 10 1570 default "10" if MAXSMP 1571 default "6" if X86_64 1572 default "3" 1573 depends on NUMA 1574 help 1575 Specify the maximum number of NUMA Nodes available on the target 1576 system. Increases memory reserved to accommodate various tables. 1577 1578config ARCH_FLATMEM_ENABLE 1579 def_bool y 1580 depends on X86_32 && !NUMA 1581 1582config ARCH_SPARSEMEM_ENABLE 1583 def_bool y 1584 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1585 select SPARSEMEM_STATIC if X86_32 1586 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1587 1588config ARCH_SPARSEMEM_DEFAULT 1589 def_bool X86_64 || (NUMA && X86_32) 1590 1591config ARCH_SELECT_MEMORY_MODEL 1592 def_bool y 1593 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1594 1595config ARCH_MEMORY_PROBE 1596 bool "Enable sysfs memory/probe interface" 1597 depends on MEMORY_HOTPLUG 1598 help 1599 This option enables a sysfs memory/probe interface for testing. 1600 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1601 If you are unsure how to answer this question, answer N. 1602 1603config ARCH_PROC_KCORE_TEXT 1604 def_bool y 1605 depends on X86_64 && PROC_KCORE 1606 1607config ILLEGAL_POINTER_VALUE 1608 hex 1609 default 0 if X86_32 1610 default 0xdead000000000000 if X86_64 1611 1612config X86_PMEM_LEGACY_DEVICE 1613 bool 1614 1615config X86_PMEM_LEGACY 1616 tristate "Support non-standard NVDIMMs and ADR protected memory" 1617 depends on PHYS_ADDR_T_64BIT 1618 depends on BLK_DEV 1619 select X86_PMEM_LEGACY_DEVICE 1620 select NUMA_KEEP_MEMINFO if NUMA 1621 select LIBNVDIMM 1622 help 1623 Treat memory marked using the non-standard e820 type of 12 as used 1624 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1625 The kernel will offer these regions to the 'pmem' driver so 1626 they can be used for persistent storage. 1627 1628 Say Y if unsure. 1629 1630config HIGHPTE 1631 bool "Allocate 3rd-level pagetables from highmem" 1632 depends on HIGHMEM 1633 help 1634 The VM uses one page table entry for each page of physical memory. 1635 For systems with a lot of RAM, this can be wasteful of precious 1636 low memory. Setting this option will put user-space page table 1637 entries in high memory. 1638 1639config X86_CHECK_BIOS_CORRUPTION 1640 bool "Check for low memory corruption" 1641 help 1642 Periodically check for memory corruption in low memory, which 1643 is suspected to be caused by BIOS. Even when enabled in the 1644 configuration, it is disabled at runtime. Enable it by 1645 setting "memory_corruption_check=1" on the kernel command 1646 line. By default it scans the low 64k of memory every 60 1647 seconds; see the memory_corruption_check_size and 1648 memory_corruption_check_period parameters in 1649 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1650 1651 When enabled with the default parameters, this option has 1652 almost no overhead, as it reserves a relatively small amount 1653 of memory and scans it infrequently. It both detects corruption 1654 and prevents it from affecting the running system. 1655 1656 It is, however, intended as a diagnostic tool; if repeatable 1657 BIOS-originated corruption always affects the same memory, 1658 you can use memmap= to prevent the kernel from using that 1659 memory. 1660 1661config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1662 bool "Set the default setting of memory_corruption_check" 1663 depends on X86_CHECK_BIOS_CORRUPTION 1664 default y 1665 help 1666 Set whether the default state of memory_corruption_check is 1667 on or off. 1668 1669config MATH_EMULATION 1670 bool 1671 depends on MODIFY_LDT_SYSCALL 1672 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1673 help 1674 Linux can emulate a math coprocessor (used for floating point 1675 operations) if you don't have one. 486DX and Pentium processors have 1676 a math coprocessor built in, 486SX and 386 do not, unless you added 1677 a 487DX or 387, respectively. (The messages during boot time can 1678 give you some hints here ["man dmesg"].) Everyone needs either a 1679 coprocessor or this emulation. 1680 1681 If you don't have a math coprocessor, you need to say Y here; if you 1682 say Y here even though you have a coprocessor, the coprocessor will 1683 be used nevertheless. (This behavior can be changed with the kernel 1684 command line option "no387", which comes handy if your coprocessor 1685 is broken. Try "man bootparam" or see the documentation of your boot 1686 loader (lilo or loadlin) about how to pass options to the kernel at 1687 boot time.) This means that it is a good idea to say Y here if you 1688 intend to use this kernel on different machines. 1689 1690 More information about the internals of the Linux math coprocessor 1691 emulation can be found in <file:arch/x86/math-emu/README>. 1692 1693 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1694 kernel, it won't hurt. 1695 1696config MTRR 1697 def_bool y 1698 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1699 help 1700 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1701 the Memory Type Range Registers (MTRRs) may be used to control 1702 processor access to memory ranges. This is most useful if you have 1703 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1704 allows bus write transfers to be combined into a larger transfer 1705 before bursting over the PCI/AGP bus. This can increase performance 1706 of image write operations 2.5 times or more. Saying Y here creates a 1707 /proc/mtrr file which may be used to manipulate your processor's 1708 MTRRs. Typically the X server should use this. 1709 1710 This code has a reasonably generic interface so that similar 1711 control registers on other processors can be easily supported 1712 as well: 1713 1714 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1715 Registers (ARRs) which provide a similar functionality to MTRRs. For 1716 these, the ARRs are used to emulate the MTRRs. 1717 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1718 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1719 write-combining. All of these processors are supported by this code 1720 and it makes sense to say Y here if you have one of them. 1721 1722 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1723 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1724 can lead to all sorts of problems, so it's good to say Y here. 1725 1726 You can safely say Y even if your machine doesn't have MTRRs, you'll 1727 just add about 9 KB to your kernel. 1728 1729 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1730 1731config MTRR_SANITIZER 1732 def_bool y 1733 prompt "MTRR cleanup support" 1734 depends on MTRR 1735 help 1736 Convert MTRR layout from continuous to discrete, so X drivers can 1737 add writeback entries. 1738 1739 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1740 The largest mtrr entry size for a continuous block can be set with 1741 mtrr_chunk_size. 1742 1743 If unsure, say Y. 1744 1745config MTRR_SANITIZER_ENABLE_DEFAULT 1746 int "MTRR cleanup enable value (0-1)" 1747 range 0 1 1748 default "0" 1749 depends on MTRR_SANITIZER 1750 help 1751 Enable mtrr cleanup default value 1752 1753config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1754 int "MTRR cleanup spare reg num (0-7)" 1755 range 0 7 1756 default "1" 1757 depends on MTRR_SANITIZER 1758 help 1759 mtrr cleanup spare entries default, it can be changed via 1760 mtrr_spare_reg_nr=N on the kernel command line. 1761 1762config X86_PAT 1763 def_bool y 1764 prompt "x86 PAT support" if EXPERT 1765 depends on MTRR 1766 help 1767 Use PAT attributes to setup page level cache control. 1768 1769 PATs are the modern equivalents of MTRRs and are much more 1770 flexible than MTRRs. 1771 1772 Say N here if you see bootup problems (boot crash, boot hang, 1773 spontaneous reboots) or a non-working video driver. 1774 1775 If unsure, say Y. 1776 1777config ARCH_USES_PG_UNCACHED 1778 def_bool y 1779 depends on X86_PAT 1780 1781config X86_UMIP 1782 def_bool y 1783 prompt "User Mode Instruction Prevention" if EXPERT 1784 help 1785 User Mode Instruction Prevention (UMIP) is a security feature in 1786 some x86 processors. If enabled, a general protection fault is 1787 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1788 executed in user mode. These instructions unnecessarily expose 1789 information about the hardware state. 1790 1791 The vast majority of applications do not use these instructions. 1792 For the very few that do, software emulation is provided in 1793 specific cases in protected and virtual-8086 modes. Emulated 1794 results are dummy. 1795 1796config CC_HAS_IBT 1797 # GCC >= 9 and binutils >= 2.29 1798 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1799 # Clang/LLVM >= 14 1800 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1801 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1802 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1803 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1804 $(as-instr,endbr64) 1805 1806config X86_CET 1807 def_bool n 1808 help 1809 CET features configured (Shadow stack or IBT) 1810 1811config X86_KERNEL_IBT 1812 prompt "Indirect Branch Tracking" 1813 def_bool y 1814 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1815 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1816 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1817 select OBJTOOL 1818 select X86_CET 1819 help 1820 Build the kernel with support for Indirect Branch Tracking, a 1821 hardware support course-grain forward-edge Control Flow Integrity 1822 protection. It enforces that all indirect calls must land on 1823 an ENDBR instruction, as such, the compiler will instrument the 1824 code with them to make this happen. 1825 1826 In addition to building the kernel with IBT, seal all functions that 1827 are not indirect call targets, avoiding them ever becoming one. 1828 1829 This requires LTO like objtool runs and will slow down the build. It 1830 does significantly reduce the number of ENDBR instructions in the 1831 kernel image. 1832 1833config X86_INTEL_MEMORY_PROTECTION_KEYS 1834 prompt "Memory Protection Keys" 1835 def_bool y 1836 # Note: only available in 64-bit mode 1837 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1838 select ARCH_USES_HIGH_VMA_FLAGS 1839 select ARCH_HAS_PKEYS 1840 help 1841 Memory Protection Keys provides a mechanism for enforcing 1842 page-based protections, but without requiring modification of the 1843 page tables when an application changes protection domains. 1844 1845 For details, see Documentation/core-api/protection-keys.rst 1846 1847 If unsure, say y. 1848 1849choice 1850 prompt "TSX enable mode" 1851 depends on CPU_SUP_INTEL 1852 default X86_INTEL_TSX_MODE_OFF 1853 help 1854 Intel's TSX (Transactional Synchronization Extensions) feature 1855 allows to optimize locking protocols through lock elision which 1856 can lead to a noticeable performance boost. 1857 1858 On the other hand it has been shown that TSX can be exploited 1859 to form side channel attacks (e.g. TAA) and chances are there 1860 will be more of those attacks discovered in the future. 1861 1862 Therefore TSX is not enabled by default (aka tsx=off). An admin 1863 might override this decision by tsx=on the command line parameter. 1864 Even with TSX enabled, the kernel will attempt to enable the best 1865 possible TAA mitigation setting depending on the microcode available 1866 for the particular machine. 1867 1868 This option allows to set the default tsx mode between tsx=on, =off 1869 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1870 details. 1871 1872 Say off if not sure, auto if TSX is in use but it should be used on safe 1873 platforms or on if TSX is in use and the security aspect of tsx is not 1874 relevant. 1875 1876config X86_INTEL_TSX_MODE_OFF 1877 bool "off" 1878 help 1879 TSX is disabled if possible - equals to tsx=off command line parameter. 1880 1881config X86_INTEL_TSX_MODE_ON 1882 bool "on" 1883 help 1884 TSX is always enabled on TSX capable HW - equals the tsx=on command 1885 line parameter. 1886 1887config X86_INTEL_TSX_MODE_AUTO 1888 bool "auto" 1889 help 1890 TSX is enabled on TSX capable HW that is believed to be safe against 1891 side channel attacks- equals the tsx=auto command line parameter. 1892endchoice 1893 1894config X86_SGX 1895 bool "Software Guard eXtensions (SGX)" 1896 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1897 depends on CRYPTO=y 1898 depends on CRYPTO_SHA256=y 1899 select MMU_NOTIFIER 1900 select NUMA_KEEP_MEMINFO if NUMA 1901 select XARRAY_MULTI 1902 help 1903 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1904 that can be used by applications to set aside private regions of code 1905 and data, referred to as enclaves. An enclave's private memory can 1906 only be accessed by code running within the enclave. Accesses from 1907 outside the enclave, including other enclaves, are disallowed by 1908 hardware. 1909 1910 If unsure, say N. 1911 1912config X86_USER_SHADOW_STACK 1913 bool "X86 userspace shadow stack" 1914 depends on AS_WRUSS 1915 depends on X86_64 1916 select ARCH_USES_HIGH_VMA_FLAGS 1917 select X86_CET 1918 help 1919 Shadow stack protection is a hardware feature that detects function 1920 return address corruption. This helps mitigate ROP attacks. 1921 Applications must be enabled to use it, and old userspace does not 1922 get protection "for free". 1923 1924 CPUs supporting shadow stacks were first released in 2020. 1925 1926 See Documentation/arch/x86/shstk.rst for more information. 1927 1928 If unsure, say N. 1929 1930config EFI 1931 bool "EFI runtime service support" 1932 depends on ACPI 1933 select UCS2_STRING 1934 select EFI_RUNTIME_WRAPPERS 1935 select ARCH_USE_MEMREMAP_PROT 1936 select EFI_RUNTIME_MAP if KEXEC_CORE 1937 help 1938 This enables the kernel to use EFI runtime services that are 1939 available (such as the EFI variable services). 1940 1941 This option is only useful on systems that have EFI firmware. 1942 In addition, you should use the latest ELILO loader available 1943 at <http://elilo.sourceforge.net> in order to take advantage 1944 of EFI runtime services. However, even with this option, the 1945 resultant kernel should continue to boot on existing non-EFI 1946 platforms. 1947 1948config EFI_STUB 1949 bool "EFI stub support" 1950 depends on EFI 1951 select RELOCATABLE 1952 help 1953 This kernel feature allows a bzImage to be loaded directly 1954 by EFI firmware without the use of a bootloader. 1955 1956 See Documentation/admin-guide/efi-stub.rst for more information. 1957 1958config EFI_HANDOVER_PROTOCOL 1959 bool "EFI handover protocol (DEPRECATED)" 1960 depends on EFI_STUB 1961 default y 1962 help 1963 Select this in order to include support for the deprecated EFI 1964 handover protocol, which defines alternative entry points into the 1965 EFI stub. This is a practice that has no basis in the UEFI 1966 specification, and requires a priori knowledge on the part of the 1967 bootloader about Linux/x86 specific ways of passing the command line 1968 and initrd, and where in memory those assets may be loaded. 1969 1970 If in doubt, say Y. Even though the corresponding support is not 1971 present in upstream GRUB or other bootloaders, most distros build 1972 GRUB with numerous downstream patches applied, and may rely on the 1973 handover protocol as as result. 1974 1975config EFI_MIXED 1976 bool "EFI mixed-mode support" 1977 depends on EFI_STUB && X86_64 1978 help 1979 Enabling this feature allows a 64-bit kernel to be booted 1980 on a 32-bit firmware, provided that your CPU supports 64-bit 1981 mode. 1982 1983 Note that it is not possible to boot a mixed-mode enabled 1984 kernel via the EFI boot stub - a bootloader that supports 1985 the EFI handover protocol must be used. 1986 1987 If unsure, say N. 1988 1989config EFI_FAKE_MEMMAP 1990 bool "Enable EFI fake memory map" 1991 depends on EFI 1992 help 1993 Saying Y here will enable "efi_fake_mem" boot option. By specifying 1994 this parameter, you can add arbitrary attribute to specific memory 1995 range by updating original (firmware provided) EFI memmap. This is 1996 useful for debugging of EFI memmap related feature, e.g., Address 1997 Range Mirroring feature. 1998 1999config EFI_MAX_FAKE_MEM 2000 int "maximum allowable number of ranges in efi_fake_mem boot option" 2001 depends on EFI_FAKE_MEMMAP 2002 range 1 128 2003 default 8 2004 help 2005 Maximum allowable number of ranges in efi_fake_mem boot option. 2006 Ranges can be set up to this value using comma-separated list. 2007 The default value is 8. 2008 2009config EFI_RUNTIME_MAP 2010 bool "Export EFI runtime maps to sysfs" if EXPERT 2011 depends on EFI 2012 help 2013 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2014 That memory map is required by the 2nd kernel to set up EFI virtual 2015 mappings after kexec, but can also be used for debugging purposes. 2016 2017 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2018 2019source "kernel/Kconfig.hz" 2020 2021config ARCH_SUPPORTS_KEXEC 2022 def_bool y 2023 2024config ARCH_SUPPORTS_KEXEC_FILE 2025 def_bool X86_64 2026 2027config ARCH_SELECTS_KEXEC_FILE 2028 def_bool y 2029 depends on KEXEC_FILE 2030 select HAVE_IMA_KEXEC if IMA 2031 2032config ARCH_SUPPORTS_KEXEC_PURGATORY 2033 def_bool y 2034 2035config ARCH_SUPPORTS_KEXEC_SIG 2036 def_bool y 2037 2038config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2039 def_bool y 2040 2041config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2042 def_bool y 2043 2044config ARCH_SUPPORTS_KEXEC_JUMP 2045 def_bool y 2046 2047config ARCH_SUPPORTS_CRASH_DUMP 2048 def_bool X86_64 || (X86_32 && HIGHMEM) 2049 2050config ARCH_SUPPORTS_CRASH_HOTPLUG 2051 def_bool y 2052 2053config PHYSICAL_START 2054 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2055 default "0x1000000" 2056 help 2057 This gives the physical address where the kernel is loaded. 2058 2059 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2060 bzImage will decompress itself to above physical address and 2061 run from there. Otherwise, bzImage will run from the address where 2062 it has been loaded by the boot loader and will ignore above physical 2063 address. 2064 2065 In normal kdump cases one does not have to set/change this option 2066 as now bzImage can be compiled as a completely relocatable image 2067 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2068 address. This option is mainly useful for the folks who don't want 2069 to use a bzImage for capturing the crash dump and want to use a 2070 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2071 to be specifically compiled to run from a specific memory area 2072 (normally a reserved region) and this option comes handy. 2073 2074 So if you are using bzImage for capturing the crash dump, 2075 leave the value here unchanged to 0x1000000 and set 2076 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2077 for capturing the crash dump change this value to start of 2078 the reserved region. In other words, it can be set based on 2079 the "X" value as specified in the "crashkernel=YM@XM" 2080 command line boot parameter passed to the panic-ed 2081 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2082 for more details about crash dumps. 2083 2084 Usage of bzImage for capturing the crash dump is recommended as 2085 one does not have to build two kernels. Same kernel can be used 2086 as production kernel and capture kernel. Above option should have 2087 gone away after relocatable bzImage support is introduced. But it 2088 is present because there are users out there who continue to use 2089 vmlinux for dump capture. This option should go away down the 2090 line. 2091 2092 Don't change this unless you know what you are doing. 2093 2094config RELOCATABLE 2095 bool "Build a relocatable kernel" 2096 default y 2097 help 2098 This builds a kernel image that retains relocation information 2099 so it can be loaded someplace besides the default 1MB. 2100 The relocations tend to make the kernel binary about 10% larger, 2101 but are discarded at runtime. 2102 2103 One use is for the kexec on panic case where the recovery kernel 2104 must live at a different physical address than the primary 2105 kernel. 2106 2107 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2108 it has been loaded at and the compile time physical address 2109 (CONFIG_PHYSICAL_START) is used as the minimum location. 2110 2111config RANDOMIZE_BASE 2112 bool "Randomize the address of the kernel image (KASLR)" 2113 depends on RELOCATABLE 2114 default y 2115 help 2116 In support of Kernel Address Space Layout Randomization (KASLR), 2117 this randomizes the physical address at which the kernel image 2118 is decompressed and the virtual address where the kernel 2119 image is mapped, as a security feature that deters exploit 2120 attempts relying on knowledge of the location of kernel 2121 code internals. 2122 2123 On 64-bit, the kernel physical and virtual addresses are 2124 randomized separately. The physical address will be anywhere 2125 between 16MB and the top of physical memory (up to 64TB). The 2126 virtual address will be randomized from 16MB up to 1GB (9 bits 2127 of entropy). Note that this also reduces the memory space 2128 available to kernel modules from 1.5GB to 1GB. 2129 2130 On 32-bit, the kernel physical and virtual addresses are 2131 randomized together. They will be randomized from 16MB up to 2132 512MB (8 bits of entropy). 2133 2134 Entropy is generated using the RDRAND instruction if it is 2135 supported. If RDTSC is supported, its value is mixed into 2136 the entropy pool as well. If neither RDRAND nor RDTSC are 2137 supported, then entropy is read from the i8254 timer. The 2138 usable entropy is limited by the kernel being built using 2139 2GB addressing, and that PHYSICAL_ALIGN must be at a 2140 minimum of 2MB. As a result, only 10 bits of entropy are 2141 theoretically possible, but the implementations are further 2142 limited due to memory layouts. 2143 2144 If unsure, say Y. 2145 2146# Relocation on x86 needs some additional build support 2147config X86_NEED_RELOCS 2148 def_bool y 2149 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2150 2151config PHYSICAL_ALIGN 2152 hex "Alignment value to which kernel should be aligned" 2153 default "0x200000" 2154 range 0x2000 0x1000000 if X86_32 2155 range 0x200000 0x1000000 if X86_64 2156 help 2157 This value puts the alignment restrictions on physical address 2158 where kernel is loaded and run from. Kernel is compiled for an 2159 address which meets above alignment restriction. 2160 2161 If bootloader loads the kernel at a non-aligned address and 2162 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2163 address aligned to above value and run from there. 2164 2165 If bootloader loads the kernel at a non-aligned address and 2166 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2167 load address and decompress itself to the address it has been 2168 compiled for and run from there. The address for which kernel is 2169 compiled already meets above alignment restrictions. Hence the 2170 end result is that kernel runs from a physical address meeting 2171 above alignment restrictions. 2172 2173 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2174 this value must be a multiple of 0x200000. 2175 2176 Don't change this unless you know what you are doing. 2177 2178config DYNAMIC_MEMORY_LAYOUT 2179 bool 2180 help 2181 This option makes base addresses of vmalloc and vmemmap as well as 2182 __PAGE_OFFSET movable during boot. 2183 2184config RANDOMIZE_MEMORY 2185 bool "Randomize the kernel memory sections" 2186 depends on X86_64 2187 depends on RANDOMIZE_BASE 2188 select DYNAMIC_MEMORY_LAYOUT 2189 default RANDOMIZE_BASE 2190 help 2191 Randomizes the base virtual address of kernel memory sections 2192 (physical memory mapping, vmalloc & vmemmap). This security feature 2193 makes exploits relying on predictable memory locations less reliable. 2194 2195 The order of allocations remains unchanged. Entropy is generated in 2196 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2197 configuration have in average 30,000 different possible virtual 2198 addresses for each memory section. 2199 2200 If unsure, say Y. 2201 2202config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2203 hex "Physical memory mapping padding" if EXPERT 2204 depends on RANDOMIZE_MEMORY 2205 default "0xa" if MEMORY_HOTPLUG 2206 default "0x0" 2207 range 0x1 0x40 if MEMORY_HOTPLUG 2208 range 0x0 0x40 2209 help 2210 Define the padding in terabytes added to the existing physical 2211 memory size during kernel memory randomization. It is useful 2212 for memory hotplug support but reduces the entropy available for 2213 address randomization. 2214 2215 If unsure, leave at the default value. 2216 2217config ADDRESS_MASKING 2218 bool "Linear Address Masking support" 2219 depends on X86_64 2220 help 2221 Linear Address Masking (LAM) modifies the checking that is applied 2222 to 64-bit linear addresses, allowing software to use of the 2223 untranslated address bits for metadata. 2224 2225 The capability can be used for efficient address sanitizers (ASAN) 2226 implementation and for optimizations in JITs. 2227 2228config HOTPLUG_CPU 2229 def_bool y 2230 depends on SMP 2231 2232config COMPAT_VDSO 2233 def_bool n 2234 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2235 depends on COMPAT_32 2236 help 2237 Certain buggy versions of glibc will crash if they are 2238 presented with a 32-bit vDSO that is not mapped at the address 2239 indicated in its segment table. 2240 2241 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2242 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2243 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2244 the only released version with the bug, but OpenSUSE 9 2245 contains a buggy "glibc 2.3.2". 2246 2247 The symptom of the bug is that everything crashes on startup, saying: 2248 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2249 2250 Saying Y here changes the default value of the vdso32 boot 2251 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2252 This works around the glibc bug but hurts performance. 2253 2254 If unsure, say N: if you are compiling your own kernel, you 2255 are unlikely to be using a buggy version of glibc. 2256 2257choice 2258 prompt "vsyscall table for legacy applications" 2259 depends on X86_64 2260 default LEGACY_VSYSCALL_XONLY 2261 help 2262 Legacy user code that does not know how to find the vDSO expects 2263 to be able to issue three syscalls by calling fixed addresses in 2264 kernel space. Since this location is not randomized with ASLR, 2265 it can be used to assist security vulnerability exploitation. 2266 2267 This setting can be changed at boot time via the kernel command 2268 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2269 is deprecated and can only be enabled using the kernel command 2270 line. 2271 2272 On a system with recent enough glibc (2.14 or newer) and no 2273 static binaries, you can say None without a performance penalty 2274 to improve security. 2275 2276 If unsure, select "Emulate execution only". 2277 2278 config LEGACY_VSYSCALL_XONLY 2279 bool "Emulate execution only" 2280 help 2281 The kernel traps and emulates calls into the fixed vsyscall 2282 address mapping and does not allow reads. This 2283 configuration is recommended when userspace might use the 2284 legacy vsyscall area but support for legacy binary 2285 instrumentation of legacy code is not needed. It mitigates 2286 certain uses of the vsyscall area as an ASLR-bypassing 2287 buffer. 2288 2289 config LEGACY_VSYSCALL_NONE 2290 bool "None" 2291 help 2292 There will be no vsyscall mapping at all. This will 2293 eliminate any risk of ASLR bypass due to the vsyscall 2294 fixed address mapping. Attempts to use the vsyscalls 2295 will be reported to dmesg, so that either old or 2296 malicious userspace programs can be identified. 2297 2298endchoice 2299 2300config CMDLINE_BOOL 2301 bool "Built-in kernel command line" 2302 help 2303 Allow for specifying boot arguments to the kernel at 2304 build time. On some systems (e.g. embedded ones), it is 2305 necessary or convenient to provide some or all of the 2306 kernel boot arguments with the kernel itself (that is, 2307 to not rely on the boot loader to provide them.) 2308 2309 To compile command line arguments into the kernel, 2310 set this option to 'Y', then fill in the 2311 boot arguments in CONFIG_CMDLINE. 2312 2313 Systems with fully functional boot loaders (i.e. non-embedded) 2314 should leave this option set to 'N'. 2315 2316config CMDLINE 2317 string "Built-in kernel command string" 2318 depends on CMDLINE_BOOL 2319 default "" 2320 help 2321 Enter arguments here that should be compiled into the kernel 2322 image and used at boot time. If the boot loader provides a 2323 command line at boot time, it is appended to this string to 2324 form the full kernel command line, when the system boots. 2325 2326 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2327 change this behavior. 2328 2329 In most cases, the command line (whether built-in or provided 2330 by the boot loader) should specify the device for the root 2331 file system. 2332 2333config CMDLINE_OVERRIDE 2334 bool "Built-in command line overrides boot loader arguments" 2335 depends on CMDLINE_BOOL && CMDLINE != "" 2336 help 2337 Set this option to 'Y' to have the kernel ignore the boot loader 2338 command line, and use ONLY the built-in command line. 2339 2340 This is used to work around broken boot loaders. This should 2341 be set to 'N' under normal conditions. 2342 2343config MODIFY_LDT_SYSCALL 2344 bool "Enable the LDT (local descriptor table)" if EXPERT 2345 default y 2346 help 2347 Linux can allow user programs to install a per-process x86 2348 Local Descriptor Table (LDT) using the modify_ldt(2) system 2349 call. This is required to run 16-bit or segmented code such as 2350 DOSEMU or some Wine programs. It is also used by some very old 2351 threading libraries. 2352 2353 Enabling this feature adds a small amount of overhead to 2354 context switches and increases the low-level kernel attack 2355 surface. Disabling it removes the modify_ldt(2) system call. 2356 2357 Saying 'N' here may make sense for embedded or server kernels. 2358 2359config STRICT_SIGALTSTACK_SIZE 2360 bool "Enforce strict size checking for sigaltstack" 2361 depends on DYNAMIC_SIGFRAME 2362 help 2363 For historical reasons MINSIGSTKSZ is a constant which became 2364 already too small with AVX512 support. Add a mechanism to 2365 enforce strict checking of the sigaltstack size against the 2366 real size of the FPU frame. This option enables the check 2367 by default. It can also be controlled via the kernel command 2368 line option 'strict_sas_size' independent of this config 2369 switch. Enabling it might break existing applications which 2370 allocate a too small sigaltstack but 'work' because they 2371 never get a signal delivered. 2372 2373 Say 'N' unless you want to really enforce this check. 2374 2375source "kernel/livepatch/Kconfig" 2376 2377endmenu 2378 2379config CC_HAS_SLS 2380 def_bool $(cc-option,-mharden-sls=all) 2381 2382config CC_HAS_RETURN_THUNK 2383 def_bool $(cc-option,-mfunction-return=thunk-extern) 2384 2385config CC_HAS_ENTRY_PADDING 2386 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2387 2388config FUNCTION_PADDING_CFI 2389 int 2390 default 59 if FUNCTION_ALIGNMENT_64B 2391 default 27 if FUNCTION_ALIGNMENT_32B 2392 default 11 if FUNCTION_ALIGNMENT_16B 2393 default 3 if FUNCTION_ALIGNMENT_8B 2394 default 0 2395 2396# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2397# except Kconfig can't do arithmetic :/ 2398config FUNCTION_PADDING_BYTES 2399 int 2400 default FUNCTION_PADDING_CFI if CFI_CLANG 2401 default FUNCTION_ALIGNMENT 2402 2403config CALL_PADDING 2404 def_bool n 2405 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2406 select FUNCTION_ALIGNMENT_16B 2407 2408config FINEIBT 2409 def_bool y 2410 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE 2411 select CALL_PADDING 2412 2413config HAVE_CALL_THUNKS 2414 def_bool y 2415 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL 2416 2417config CALL_THUNKS 2418 def_bool n 2419 select CALL_PADDING 2420 2421config PREFIX_SYMBOLS 2422 def_bool y 2423 depends on CALL_PADDING && !CFI_CLANG 2424 2425menuconfig CPU_MITIGATIONS 2426 bool "Mitigations for CPU vulnerabilities" 2427 default y 2428 help 2429 Say Y here to enable options which enable mitigations for hardware 2430 vulnerabilities (usually related to speculative execution). 2431 Mitigations can be disabled or restricted to SMT systems at runtime 2432 via the "mitigations" kernel parameter. 2433 2434 If you say N, all mitigations will be disabled. This CANNOT be 2435 overridden at runtime. 2436 2437 Say 'Y', unless you really know what you are doing. 2438 2439if CPU_MITIGATIONS 2440 2441config PAGE_TABLE_ISOLATION 2442 bool "Remove the kernel mapping in user mode" 2443 default y 2444 depends on (X86_64 || X86_PAE) 2445 help 2446 This feature reduces the number of hardware side channels by 2447 ensuring that the majority of kernel addresses are not mapped 2448 into userspace. 2449 2450 See Documentation/arch/x86/pti.rst for more details. 2451 2452config RETPOLINE 2453 bool "Avoid speculative indirect branches in kernel" 2454 select OBJTOOL if HAVE_OBJTOOL 2455 default y 2456 help 2457 Compile kernel with the retpoline compiler options to guard against 2458 kernel-to-user data leaks by avoiding speculative indirect 2459 branches. Requires a compiler with -mindirect-branch=thunk-extern 2460 support for full protection. The kernel may run slower. 2461 2462config RETHUNK 2463 bool "Enable return-thunks" 2464 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2465 select OBJTOOL if HAVE_OBJTOOL 2466 default y if X86_64 2467 help 2468 Compile the kernel with the return-thunks compiler option to guard 2469 against kernel-to-user data leaks by avoiding return speculation. 2470 Requires a compiler with -mfunction-return=thunk-extern 2471 support for full protection. The kernel may run slower. 2472 2473config CPU_UNRET_ENTRY 2474 bool "Enable UNRET on kernel entry" 2475 depends on CPU_SUP_AMD && RETHUNK && X86_64 2476 default y 2477 help 2478 Compile the kernel with support for the retbleed=unret mitigation. 2479 2480config CALL_DEPTH_TRACKING 2481 bool "Mitigate RSB underflow with call depth tracking" 2482 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2483 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2484 select CALL_THUNKS 2485 default y 2486 help 2487 Compile the kernel with call depth tracking to mitigate the Intel 2488 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2489 mitigation is off by default and needs to be enabled on the 2490 kernel command line via the retbleed=stuff option. For 2491 non-affected systems the overhead of this option is marginal as 2492 the call depth tracking is using run-time generated call thunks 2493 in a compiler generated padding area and call patching. This 2494 increases text size by ~5%. For non affected systems this space 2495 is unused. On affected SKL systems this results in a significant 2496 performance gain over the IBRS mitigation. 2497 2498config CALL_THUNKS_DEBUG 2499 bool "Enable call thunks and call depth tracking debugging" 2500 depends on CALL_DEPTH_TRACKING 2501 select FUNCTION_ALIGNMENT_32B 2502 default n 2503 help 2504 Enable call/ret counters for imbalance detection and build in 2505 a noisy dmesg about callthunks generation and call patching for 2506 trouble shooting. The debug prints need to be enabled on the 2507 kernel command line with 'debug-callthunks'. 2508 Only enable this when you are debugging call thunks as this 2509 creates a noticeable runtime overhead. If unsure say N. 2510 2511config CPU_IBPB_ENTRY 2512 bool "Enable IBPB on kernel entry" 2513 depends on CPU_SUP_AMD && X86_64 2514 default y 2515 help 2516 Compile the kernel with support for the retbleed=ibpb mitigation. 2517 2518config CPU_IBRS_ENTRY 2519 bool "Enable IBRS on kernel entry" 2520 depends on CPU_SUP_INTEL && X86_64 2521 default y 2522 help 2523 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2524 This mitigates both spectre_v2 and retbleed at great cost to 2525 performance. 2526 2527config CPU_SRSO 2528 bool "Mitigate speculative RAS overflow on AMD" 2529 depends on CPU_SUP_AMD && X86_64 && RETHUNK 2530 default y 2531 help 2532 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2533 2534config SLS 2535 bool "Mitigate Straight-Line-Speculation" 2536 depends on CC_HAS_SLS && X86_64 2537 select OBJTOOL if HAVE_OBJTOOL 2538 default n 2539 help 2540 Compile the kernel with straight-line-speculation options to guard 2541 against straight line speculation. The kernel image might be slightly 2542 larger. 2543 2544config GDS_FORCE_MITIGATION 2545 bool "Force GDS Mitigation" 2546 depends on CPU_SUP_INTEL 2547 default n 2548 help 2549 Gather Data Sampling (GDS) is a hardware vulnerability which allows 2550 unprivileged speculative access to data which was previously stored in 2551 vector registers. 2552 2553 This option is equivalent to setting gather_data_sampling=force on the 2554 command line. The microcode mitigation is used if present, otherwise 2555 AVX is disabled as a mitigation. On affected systems that are missing 2556 the microcode any userspace code that unconditionally uses AVX will 2557 break with this option set. 2558 2559 Setting this option on systems not vulnerable to GDS has no effect. 2560 2561 If in doubt, say N. 2562 2563config MITIGATION_RFDS 2564 bool "RFDS Mitigation" 2565 depends on CPU_SUP_INTEL 2566 default y 2567 help 2568 Enable mitigation for Register File Data Sampling (RFDS) by default. 2569 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2570 allows unprivileged speculative access to stale data previously 2571 stored in floating point, vector and integer registers. 2572 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2573 2574config MITIGATION_SPECTRE_BHI 2575 bool "Mitigate Spectre-BHB (Branch History Injection)" 2576 depends on CPU_SUP_INTEL 2577 default y 2578 help 2579 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2580 where the branch history buffer is poisoned to speculatively steer 2581 indirect branches. 2582 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2583 2584endif 2585 2586config ARCH_HAS_ADD_PAGES 2587 def_bool y 2588 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2589 2590menu "Power management and ACPI options" 2591 2592config ARCH_HIBERNATION_HEADER 2593 def_bool y 2594 depends on HIBERNATION 2595 2596source "kernel/power/Kconfig" 2597 2598source "drivers/acpi/Kconfig" 2599 2600config X86_APM_BOOT 2601 def_bool y 2602 depends on APM 2603 2604menuconfig APM 2605 tristate "APM (Advanced Power Management) BIOS support" 2606 depends on X86_32 && PM_SLEEP 2607 help 2608 APM is a BIOS specification for saving power using several different 2609 techniques. This is mostly useful for battery powered laptops with 2610 APM compliant BIOSes. If you say Y here, the system time will be 2611 reset after a RESUME operation, the /proc/apm device will provide 2612 battery status information, and user-space programs will receive 2613 notification of APM "events" (e.g. battery status change). 2614 2615 If you select "Y" here, you can disable actual use of the APM 2616 BIOS by passing the "apm=off" option to the kernel at boot time. 2617 2618 Note that the APM support is almost completely disabled for 2619 machines with more than one CPU. 2620 2621 In order to use APM, you will need supporting software. For location 2622 and more information, read <file:Documentation/power/apm-acpi.rst> 2623 and the Battery Powered Linux mini-HOWTO, available from 2624 <http://www.tldp.org/docs.html#howto>. 2625 2626 This driver does not spin down disk drives (see the hdparm(8) 2627 manpage ("man 8 hdparm") for that), and it doesn't turn off 2628 VESA-compliant "green" monitors. 2629 2630 This driver does not support the TI 4000M TravelMate and the ACER 2631 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2632 desktop machines also don't have compliant BIOSes, and this driver 2633 may cause those machines to panic during the boot phase. 2634 2635 Generally, if you don't have a battery in your machine, there isn't 2636 much point in using this driver and you should say N. If you get 2637 random kernel OOPSes or reboots that don't seem to be related to 2638 anything, try disabling/enabling this option (or disabling/enabling 2639 APM in your BIOS). 2640 2641 Some other things you should try when experiencing seemingly random, 2642 "weird" problems: 2643 2644 1) make sure that you have enough swap space and that it is 2645 enabled. 2646 2) pass the "idle=poll" option to the kernel 2647 3) switch on floating point emulation in the kernel and pass 2648 the "no387" option to the kernel 2649 4) pass the "floppy=nodma" option to the kernel 2650 5) pass the "mem=4M" option to the kernel (thereby disabling 2651 all but the first 4 MB of RAM) 2652 6) make sure that the CPU is not over clocked. 2653 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2654 8) disable the cache from your BIOS settings 2655 9) install a fan for the video card or exchange video RAM 2656 10) install a better fan for the CPU 2657 11) exchange RAM chips 2658 12) exchange the motherboard. 2659 2660 To compile this driver as a module, choose M here: the 2661 module will be called apm. 2662 2663if APM 2664 2665config APM_IGNORE_USER_SUSPEND 2666 bool "Ignore USER SUSPEND" 2667 help 2668 This option will ignore USER SUSPEND requests. On machines with a 2669 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2670 series notebooks, it is necessary to say Y because of a BIOS bug. 2671 2672config APM_DO_ENABLE 2673 bool "Enable PM at boot time" 2674 help 2675 Enable APM features at boot time. From page 36 of the APM BIOS 2676 specification: "When disabled, the APM BIOS does not automatically 2677 power manage devices, enter the Standby State, enter the Suspend 2678 State, or take power saving steps in response to CPU Idle calls." 2679 This driver will make CPU Idle calls when Linux is idle (unless this 2680 feature is turned off -- see "Do CPU IDLE calls", below). This 2681 should always save battery power, but more complicated APM features 2682 will be dependent on your BIOS implementation. You may need to turn 2683 this option off if your computer hangs at boot time when using APM 2684 support, or if it beeps continuously instead of suspending. Turn 2685 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2686 T400CDT. This is off by default since most machines do fine without 2687 this feature. 2688 2689config APM_CPU_IDLE 2690 depends on CPU_IDLE 2691 bool "Make CPU Idle calls when idle" 2692 help 2693 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2694 On some machines, this can activate improved power savings, such as 2695 a slowed CPU clock rate, when the machine is idle. These idle calls 2696 are made after the idle loop has run for some length of time (e.g., 2697 333 mS). On some machines, this will cause a hang at boot time or 2698 whenever the CPU becomes idle. (On machines with more than one CPU, 2699 this option does nothing.) 2700 2701config APM_DISPLAY_BLANK 2702 bool "Enable console blanking using APM" 2703 help 2704 Enable console blanking using the APM. Some laptops can use this to 2705 turn off the LCD backlight when the screen blanker of the Linux 2706 virtual console blanks the screen. Note that this is only used by 2707 the virtual console screen blanker, and won't turn off the backlight 2708 when using the X Window system. This also doesn't have anything to 2709 do with your VESA-compliant power-saving monitor. Further, this 2710 option doesn't work for all laptops -- it might not turn off your 2711 backlight at all, or it might print a lot of errors to the console, 2712 especially if you are using gpm. 2713 2714config APM_ALLOW_INTS 2715 bool "Allow interrupts during APM BIOS calls" 2716 help 2717 Normally we disable external interrupts while we are making calls to 2718 the APM BIOS as a measure to lessen the effects of a badly behaving 2719 BIOS implementation. The BIOS should reenable interrupts if it 2720 needs to. Unfortunately, some BIOSes do not -- especially those in 2721 many of the newer IBM Thinkpads. If you experience hangs when you 2722 suspend, try setting this to Y. Otherwise, say N. 2723 2724endif # APM 2725 2726source "drivers/cpufreq/Kconfig" 2727 2728source "drivers/cpuidle/Kconfig" 2729 2730source "drivers/idle/Kconfig" 2731 2732endmenu 2733 2734menu "Bus options (PCI etc.)" 2735 2736choice 2737 prompt "PCI access mode" 2738 depends on X86_32 && PCI 2739 default PCI_GOANY 2740 help 2741 On PCI systems, the BIOS can be used to detect the PCI devices and 2742 determine their configuration. However, some old PCI motherboards 2743 have BIOS bugs and may crash if this is done. Also, some embedded 2744 PCI-based systems don't have any BIOS at all. Linux can also try to 2745 detect the PCI hardware directly without using the BIOS. 2746 2747 With this option, you can specify how Linux should detect the 2748 PCI devices. If you choose "BIOS", the BIOS will be used, 2749 if you choose "Direct", the BIOS won't be used, and if you 2750 choose "MMConfig", then PCI Express MMCONFIG will be used. 2751 If you choose "Any", the kernel will try MMCONFIG, then the 2752 direct access method and falls back to the BIOS if that doesn't 2753 work. If unsure, go with the default, which is "Any". 2754 2755config PCI_GOBIOS 2756 bool "BIOS" 2757 2758config PCI_GOMMCONFIG 2759 bool "MMConfig" 2760 2761config PCI_GODIRECT 2762 bool "Direct" 2763 2764config PCI_GOOLPC 2765 bool "OLPC XO-1" 2766 depends on OLPC 2767 2768config PCI_GOANY 2769 bool "Any" 2770 2771endchoice 2772 2773config PCI_BIOS 2774 def_bool y 2775 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2776 2777# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2778config PCI_DIRECT 2779 def_bool y 2780 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2781 2782config PCI_MMCONFIG 2783 bool "Support mmconfig PCI config space access" if X86_64 2784 default y 2785 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2786 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2787 2788config PCI_OLPC 2789 def_bool y 2790 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2791 2792config PCI_XEN 2793 def_bool y 2794 depends on PCI && XEN 2795 2796config MMCONF_FAM10H 2797 def_bool y 2798 depends on X86_64 && PCI_MMCONFIG && ACPI 2799 2800config PCI_CNB20LE_QUIRK 2801 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2802 depends on PCI 2803 help 2804 Read the PCI windows out of the CNB20LE host bridge. This allows 2805 PCI hotplug to work on systems with the CNB20LE chipset which do 2806 not have ACPI. 2807 2808 There's no public spec for this chipset, and this functionality 2809 is known to be incomplete. 2810 2811 You should say N unless you know you need this. 2812 2813config ISA_BUS 2814 bool "ISA bus support on modern systems" if EXPERT 2815 help 2816 Expose ISA bus device drivers and options available for selection and 2817 configuration. Enable this option if your target machine has an ISA 2818 bus. ISA is an older system, displaced by PCI and newer bus 2819 architectures -- if your target machine is modern, it probably does 2820 not have an ISA bus. 2821 2822 If unsure, say N. 2823 2824# x86_64 have no ISA slots, but can have ISA-style DMA. 2825config ISA_DMA_API 2826 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2827 default y 2828 help 2829 Enables ISA-style DMA support for devices requiring such controllers. 2830 If unsure, say Y. 2831 2832if X86_32 2833 2834config ISA 2835 bool "ISA support" 2836 help 2837 Find out whether you have ISA slots on your motherboard. ISA is the 2838 name of a bus system, i.e. the way the CPU talks to the other stuff 2839 inside your box. Other bus systems are PCI, EISA, MicroChannel 2840 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2841 newer boards don't support it. If you have ISA, say Y, otherwise N. 2842 2843config SCx200 2844 tristate "NatSemi SCx200 support" 2845 help 2846 This provides basic support for National Semiconductor's 2847 (now AMD's) Geode processors. The driver probes for the 2848 PCI-IDs of several on-chip devices, so its a good dependency 2849 for other scx200_* drivers. 2850 2851 If compiled as a module, the driver is named scx200. 2852 2853config SCx200HR_TIMER 2854 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2855 depends on SCx200 2856 default y 2857 help 2858 This driver provides a clocksource built upon the on-chip 2859 27MHz high-resolution timer. Its also a workaround for 2860 NSC Geode SC-1100's buggy TSC, which loses time when the 2861 processor goes idle (as is done by the scheduler). The 2862 other workaround is idle=poll boot option. 2863 2864config OLPC 2865 bool "One Laptop Per Child support" 2866 depends on !X86_PAE 2867 select GPIOLIB 2868 select OF 2869 select OF_PROMTREE 2870 select IRQ_DOMAIN 2871 select OLPC_EC 2872 help 2873 Add support for detecting the unique features of the OLPC 2874 XO hardware. 2875 2876config OLPC_XO1_PM 2877 bool "OLPC XO-1 Power Management" 2878 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2879 help 2880 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2881 2882config OLPC_XO1_RTC 2883 bool "OLPC XO-1 Real Time Clock" 2884 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2885 help 2886 Add support for the XO-1 real time clock, which can be used as a 2887 programmable wakeup source. 2888 2889config OLPC_XO1_SCI 2890 bool "OLPC XO-1 SCI extras" 2891 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2892 depends on INPUT=y 2893 select POWER_SUPPLY 2894 help 2895 Add support for SCI-based features of the OLPC XO-1 laptop: 2896 - EC-driven system wakeups 2897 - Power button 2898 - Ebook switch 2899 - Lid switch 2900 - AC adapter status updates 2901 - Battery status updates 2902 2903config OLPC_XO15_SCI 2904 bool "OLPC XO-1.5 SCI extras" 2905 depends on OLPC && ACPI 2906 select POWER_SUPPLY 2907 help 2908 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2909 - EC-driven system wakeups 2910 - AC adapter status updates 2911 - Battery status updates 2912 2913config ALIX 2914 bool "PCEngines ALIX System Support (LED setup)" 2915 select GPIOLIB 2916 help 2917 This option enables system support for the PCEngines ALIX. 2918 At present this just sets up LEDs for GPIO control on 2919 ALIX2/3/6 boards. However, other system specific setup should 2920 get added here. 2921 2922 Note: You must still enable the drivers for GPIO and LED support 2923 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2924 2925 Note: You have to set alix.force=1 for boards with Award BIOS. 2926 2927config NET5501 2928 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2929 select GPIOLIB 2930 help 2931 This option enables system support for the Soekris Engineering net5501. 2932 2933config GEOS 2934 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2935 select GPIOLIB 2936 depends on DMI 2937 help 2938 This option enables system support for the Traverse Technologies GEOS. 2939 2940config TS5500 2941 bool "Technologic Systems TS-5500 platform support" 2942 depends on MELAN 2943 select CHECK_SIGNATURE 2944 select NEW_LEDS 2945 select LEDS_CLASS 2946 help 2947 This option enables system support for the Technologic Systems TS-5500. 2948 2949endif # X86_32 2950 2951config AMD_NB 2952 def_bool y 2953 depends on CPU_SUP_AMD && PCI 2954 2955endmenu 2956 2957menu "Binary Emulations" 2958 2959config IA32_EMULATION 2960 bool "IA32 Emulation" 2961 depends on X86_64 2962 select ARCH_WANT_OLD_COMPAT_IPC 2963 select BINFMT_ELF 2964 select COMPAT_OLD_SIGACTION 2965 help 2966 Include code to run legacy 32-bit programs under a 2967 64-bit kernel. You should likely turn this on, unless you're 2968 100% sure that you don't have any 32-bit programs left. 2969 2970config X86_X32_ABI 2971 bool "x32 ABI for 64-bit mode" 2972 depends on X86_64 2973 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2974 # compressed debug sections to x86_x32 properly: 2975 # https://github.com/ClangBuiltLinux/linux/issues/514 2976 # https://github.com/ClangBuiltLinux/linux/issues/1141 2977 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 2978 help 2979 Include code to run binaries for the x32 native 32-bit ABI 2980 for 64-bit processors. An x32 process gets access to the 2981 full 64-bit register file and wide data path while leaving 2982 pointers at 32 bits for smaller memory footprint. 2983 2984config COMPAT_32 2985 def_bool y 2986 depends on IA32_EMULATION || X86_32 2987 select HAVE_UID16 2988 select OLD_SIGSUSPEND3 2989 2990config COMPAT 2991 def_bool y 2992 depends on IA32_EMULATION || X86_X32_ABI 2993 2994config COMPAT_FOR_U64_ALIGNMENT 2995 def_bool y 2996 depends on COMPAT 2997 2998endmenu 2999 3000config HAVE_ATOMIC_IOMAP 3001 def_bool y 3002 depends on X86_32 3003 3004source "arch/x86/kvm/Kconfig" 3005 3006source "arch/x86/Kconfig.assembler" 3007