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 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD 1317 1318config MICROCODE_LATE_LOADING 1319 bool "Late microcode loading (DANGEROUS)" 1320 default n 1321 depends on MICROCODE && SMP 1322 help 1323 Loading microcode late, when the system is up and executing instructions 1324 is a tricky business and should be avoided if possible. Just the sequence 1325 of synchronizing all cores and SMT threads is one fragile dance which does 1326 not guarantee that cores might not softlock after the loading. Therefore, 1327 use this at your own risk. Late loading taints the kernel unless the 1328 microcode header indicates that it is safe for late loading via the 1329 minimal revision check. This minimal revision check can be enforced on 1330 the kernel command line with "microcode.minrev=Y". 1331 1332config MICROCODE_LATE_FORCE_MINREV 1333 bool "Enforce late microcode loading minimal revision check" 1334 default n 1335 depends on MICROCODE_LATE_LOADING 1336 help 1337 To prevent that users load microcode late which modifies already 1338 in use features, newer microcode patches have a minimum revision field 1339 in the microcode header, which tells the kernel which minimum 1340 revision must be active in the CPU to safely load that new microcode 1341 late into the running system. If disabled the check will not 1342 be enforced but the kernel will be tainted when the minimal 1343 revision check fails. 1344 1345 This minimal revision check can also be controlled via the 1346 "microcode.minrev" parameter on the kernel command line. 1347 1348 If unsure say Y. 1349 1350config X86_MSR 1351 tristate "/dev/cpu/*/msr - Model-specific register support" 1352 help 1353 This device gives privileged processes access to the x86 1354 Model-Specific Registers (MSRs). It is a character device with 1355 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1356 MSR accesses are directed to a specific CPU on multi-processor 1357 systems. 1358 1359config X86_CPUID 1360 tristate "/dev/cpu/*/cpuid - CPU information support" 1361 help 1362 This device gives processes access to the x86 CPUID instruction to 1363 be executed on a specific processor. It is a character device 1364 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1365 /dev/cpu/31/cpuid. 1366 1367choice 1368 prompt "High Memory Support" 1369 default HIGHMEM4G 1370 depends on X86_32 1371 1372config NOHIGHMEM 1373 bool "off" 1374 help 1375 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1376 However, the address space of 32-bit x86 processors is only 4 1377 Gigabytes large. That means that, if you have a large amount of 1378 physical memory, not all of it can be "permanently mapped" by the 1379 kernel. The physical memory that's not permanently mapped is called 1380 "high memory". 1381 1382 If you are compiling a kernel which will never run on a machine with 1383 more than 1 Gigabyte total physical RAM, answer "off" here (default 1384 choice and suitable for most users). This will result in a "3GB/1GB" 1385 split: 3GB are mapped so that each process sees a 3GB virtual memory 1386 space and the remaining part of the 4GB virtual memory space is used 1387 by the kernel to permanently map as much physical memory as 1388 possible. 1389 1390 If the machine has between 1 and 4 Gigabytes physical RAM, then 1391 answer "4GB" here. 1392 1393 If more than 4 Gigabytes is used then answer "64GB" here. This 1394 selection turns Intel PAE (Physical Address Extension) mode on. 1395 PAE implements 3-level paging on IA32 processors. PAE is fully 1396 supported by Linux, PAE mode is implemented on all recent Intel 1397 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1398 then the kernel will not boot on CPUs that don't support PAE! 1399 1400 The actual amount of total physical memory will either be 1401 auto detected or can be forced by using a kernel command line option 1402 such as "mem=256M". (Try "man bootparam" or see the documentation of 1403 your boot loader (lilo or loadlin) about how to pass options to the 1404 kernel at boot time.) 1405 1406 If unsure, say "off". 1407 1408config HIGHMEM4G 1409 bool "4GB" 1410 help 1411 Select this if you have a 32-bit processor and between 1 and 4 1412 gigabytes of physical RAM. 1413 1414config HIGHMEM64G 1415 bool "64GB" 1416 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1417 select X86_PAE 1418 help 1419 Select this if you have a 32-bit processor and more than 4 1420 gigabytes of physical RAM. 1421 1422endchoice 1423 1424choice 1425 prompt "Memory split" if EXPERT 1426 default VMSPLIT_3G 1427 depends on X86_32 1428 help 1429 Select the desired split between kernel and user memory. 1430 1431 If the address range available to the kernel is less than the 1432 physical memory installed, the remaining memory will be available 1433 as "high memory". Accessing high memory is a little more costly 1434 than low memory, as it needs to be mapped into the kernel first. 1435 Note that increasing the kernel address space limits the range 1436 available to user programs, making the address space there 1437 tighter. Selecting anything other than the default 3G/1G split 1438 will also likely make your kernel incompatible with binary-only 1439 kernel modules. 1440 1441 If you are not absolutely sure what you are doing, leave this 1442 option alone! 1443 1444 config VMSPLIT_3G 1445 bool "3G/1G user/kernel split" 1446 config VMSPLIT_3G_OPT 1447 depends on !X86_PAE 1448 bool "3G/1G user/kernel split (for full 1G low memory)" 1449 config VMSPLIT_2G 1450 bool "2G/2G user/kernel split" 1451 config VMSPLIT_2G_OPT 1452 depends on !X86_PAE 1453 bool "2G/2G user/kernel split (for full 2G low memory)" 1454 config VMSPLIT_1G 1455 bool "1G/3G user/kernel split" 1456endchoice 1457 1458config PAGE_OFFSET 1459 hex 1460 default 0xB0000000 if VMSPLIT_3G_OPT 1461 default 0x80000000 if VMSPLIT_2G 1462 default 0x78000000 if VMSPLIT_2G_OPT 1463 default 0x40000000 if VMSPLIT_1G 1464 default 0xC0000000 1465 depends on X86_32 1466 1467config HIGHMEM 1468 def_bool y 1469 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1470 1471config X86_PAE 1472 bool "PAE (Physical Address Extension) Support" 1473 depends on X86_32 && !HIGHMEM4G 1474 select PHYS_ADDR_T_64BIT 1475 select SWIOTLB 1476 help 1477 PAE is required for NX support, and furthermore enables 1478 larger swapspace support for non-overcommit purposes. It 1479 has the cost of more pagetable lookup overhead, and also 1480 consumes more pagetable space per process. 1481 1482config X86_5LEVEL 1483 bool "Enable 5-level page tables support" 1484 default y 1485 select DYNAMIC_MEMORY_LAYOUT 1486 select SPARSEMEM_VMEMMAP 1487 depends on X86_64 1488 help 1489 5-level paging enables access to larger address space: 1490 up to 128 PiB of virtual address space and 4 PiB of 1491 physical address space. 1492 1493 It will be supported by future Intel CPUs. 1494 1495 A kernel with the option enabled can be booted on machines that 1496 support 4- or 5-level paging. 1497 1498 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1499 information. 1500 1501 Say N if unsure. 1502 1503config X86_DIRECT_GBPAGES 1504 def_bool y 1505 depends on X86_64 1506 help 1507 Certain kernel features effectively disable kernel 1508 linear 1 GB mappings (even if the CPU otherwise 1509 supports them), so don't confuse the user by printing 1510 that we have them enabled. 1511 1512config X86_CPA_STATISTICS 1513 bool "Enable statistic for Change Page Attribute" 1514 depends on DEBUG_FS 1515 help 1516 Expose statistics about the Change Page Attribute mechanism, which 1517 helps to determine the effectiveness of preserving large and huge 1518 page mappings when mapping protections are changed. 1519 1520config X86_MEM_ENCRYPT 1521 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1522 select DYNAMIC_PHYSICAL_MASK 1523 def_bool n 1524 1525config AMD_MEM_ENCRYPT 1526 bool "AMD Secure Memory Encryption (SME) support" 1527 depends on X86_64 && CPU_SUP_AMD 1528 depends on EFI_STUB 1529 select DMA_COHERENT_POOL 1530 select ARCH_USE_MEMREMAP_PROT 1531 select INSTRUCTION_DECODER 1532 select ARCH_HAS_CC_PLATFORM 1533 select X86_MEM_ENCRYPT 1534 select UNACCEPTED_MEMORY 1535 help 1536 Say yes to enable support for the encryption of system memory. 1537 This requires an AMD processor that supports Secure Memory 1538 Encryption (SME). 1539 1540# Common NUMA Features 1541config NUMA 1542 bool "NUMA Memory Allocation and Scheduler Support" 1543 depends on SMP 1544 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1545 default y if X86_BIGSMP 1546 select USE_PERCPU_NUMA_NODE_ID 1547 help 1548 Enable NUMA (Non-Uniform Memory Access) support. 1549 1550 The kernel will try to allocate memory used by a CPU on the 1551 local memory controller of the CPU and add some more 1552 NUMA awareness to the kernel. 1553 1554 For 64-bit this is recommended if the system is Intel Core i7 1555 (or later), AMD Opteron, or EM64T NUMA. 1556 1557 For 32-bit this is only needed if you boot a 32-bit 1558 kernel on a 64-bit NUMA platform. 1559 1560 Otherwise, you should say N. 1561 1562config AMD_NUMA 1563 def_bool y 1564 prompt "Old style AMD Opteron NUMA detection" 1565 depends on X86_64 && NUMA && PCI 1566 help 1567 Enable AMD NUMA node topology detection. You should say Y here if 1568 you have a multi processor AMD system. This uses an old method to 1569 read the NUMA configuration directly from the builtin Northbridge 1570 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1571 which also takes priority if both are compiled in. 1572 1573config X86_64_ACPI_NUMA 1574 def_bool y 1575 prompt "ACPI NUMA detection" 1576 depends on X86_64 && NUMA && ACPI && PCI 1577 select ACPI_NUMA 1578 help 1579 Enable ACPI SRAT based node topology detection. 1580 1581config NUMA_EMU 1582 bool "NUMA emulation" 1583 depends on NUMA 1584 help 1585 Enable NUMA emulation. A flat machine will be split 1586 into virtual nodes when booted with "numa=fake=N", where N is the 1587 number of nodes. This is only useful for debugging. 1588 1589config NODES_SHIFT 1590 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1591 range 1 10 1592 default "10" if MAXSMP 1593 default "6" if X86_64 1594 default "3" 1595 depends on NUMA 1596 help 1597 Specify the maximum number of NUMA Nodes available on the target 1598 system. Increases memory reserved to accommodate various tables. 1599 1600config ARCH_FLATMEM_ENABLE 1601 def_bool y 1602 depends on X86_32 && !NUMA 1603 1604config ARCH_SPARSEMEM_ENABLE 1605 def_bool y 1606 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1607 select SPARSEMEM_STATIC if X86_32 1608 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1609 1610config ARCH_SPARSEMEM_DEFAULT 1611 def_bool X86_64 || (NUMA && X86_32) 1612 1613config ARCH_SELECT_MEMORY_MODEL 1614 def_bool y 1615 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1616 1617config ARCH_MEMORY_PROBE 1618 bool "Enable sysfs memory/probe interface" 1619 depends on MEMORY_HOTPLUG 1620 help 1621 This option enables a sysfs memory/probe interface for testing. 1622 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1623 If you are unsure how to answer this question, answer N. 1624 1625config ARCH_PROC_KCORE_TEXT 1626 def_bool y 1627 depends on X86_64 && PROC_KCORE 1628 1629config ILLEGAL_POINTER_VALUE 1630 hex 1631 default 0 if X86_32 1632 default 0xdead000000000000 if X86_64 1633 1634config X86_PMEM_LEGACY_DEVICE 1635 bool 1636 1637config X86_PMEM_LEGACY 1638 tristate "Support non-standard NVDIMMs and ADR protected memory" 1639 depends on PHYS_ADDR_T_64BIT 1640 depends on BLK_DEV 1641 select X86_PMEM_LEGACY_DEVICE 1642 select NUMA_KEEP_MEMINFO if NUMA 1643 select LIBNVDIMM 1644 help 1645 Treat memory marked using the non-standard e820 type of 12 as used 1646 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1647 The kernel will offer these regions to the 'pmem' driver so 1648 they can be used for persistent storage. 1649 1650 Say Y if unsure. 1651 1652config HIGHPTE 1653 bool "Allocate 3rd-level pagetables from highmem" 1654 depends on HIGHMEM 1655 help 1656 The VM uses one page table entry for each page of physical memory. 1657 For systems with a lot of RAM, this can be wasteful of precious 1658 low memory. Setting this option will put user-space page table 1659 entries in high memory. 1660 1661config X86_CHECK_BIOS_CORRUPTION 1662 bool "Check for low memory corruption" 1663 help 1664 Periodically check for memory corruption in low memory, which 1665 is suspected to be caused by BIOS. Even when enabled in the 1666 configuration, it is disabled at runtime. Enable it by 1667 setting "memory_corruption_check=1" on the kernel command 1668 line. By default it scans the low 64k of memory every 60 1669 seconds; see the memory_corruption_check_size and 1670 memory_corruption_check_period parameters in 1671 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1672 1673 When enabled with the default parameters, this option has 1674 almost no overhead, as it reserves a relatively small amount 1675 of memory and scans it infrequently. It both detects corruption 1676 and prevents it from affecting the running system. 1677 1678 It is, however, intended as a diagnostic tool; if repeatable 1679 BIOS-originated corruption always affects the same memory, 1680 you can use memmap= to prevent the kernel from using that 1681 memory. 1682 1683config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1684 bool "Set the default setting of memory_corruption_check" 1685 depends on X86_CHECK_BIOS_CORRUPTION 1686 default y 1687 help 1688 Set whether the default state of memory_corruption_check is 1689 on or off. 1690 1691config MATH_EMULATION 1692 bool 1693 depends on MODIFY_LDT_SYSCALL 1694 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1695 help 1696 Linux can emulate a math coprocessor (used for floating point 1697 operations) if you don't have one. 486DX and Pentium processors have 1698 a math coprocessor built in, 486SX and 386 do not, unless you added 1699 a 487DX or 387, respectively. (The messages during boot time can 1700 give you some hints here ["man dmesg"].) Everyone needs either a 1701 coprocessor or this emulation. 1702 1703 If you don't have a math coprocessor, you need to say Y here; if you 1704 say Y here even though you have a coprocessor, the coprocessor will 1705 be used nevertheless. (This behavior can be changed with the kernel 1706 command line option "no387", which comes handy if your coprocessor 1707 is broken. Try "man bootparam" or see the documentation of your boot 1708 loader (lilo or loadlin) about how to pass options to the kernel at 1709 boot time.) This means that it is a good idea to say Y here if you 1710 intend to use this kernel on different machines. 1711 1712 More information about the internals of the Linux math coprocessor 1713 emulation can be found in <file:arch/x86/math-emu/README>. 1714 1715 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1716 kernel, it won't hurt. 1717 1718config MTRR 1719 def_bool y 1720 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1721 help 1722 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1723 the Memory Type Range Registers (MTRRs) may be used to control 1724 processor access to memory ranges. This is most useful if you have 1725 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1726 allows bus write transfers to be combined into a larger transfer 1727 before bursting over the PCI/AGP bus. This can increase performance 1728 of image write operations 2.5 times or more. Saying Y here creates a 1729 /proc/mtrr file which may be used to manipulate your processor's 1730 MTRRs. Typically the X server should use this. 1731 1732 This code has a reasonably generic interface so that similar 1733 control registers on other processors can be easily supported 1734 as well: 1735 1736 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1737 Registers (ARRs) which provide a similar functionality to MTRRs. For 1738 these, the ARRs are used to emulate the MTRRs. 1739 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1740 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1741 write-combining. All of these processors are supported by this code 1742 and it makes sense to say Y here if you have one of them. 1743 1744 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1745 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1746 can lead to all sorts of problems, so it's good to say Y here. 1747 1748 You can safely say Y even if your machine doesn't have MTRRs, you'll 1749 just add about 9 KB to your kernel. 1750 1751 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1752 1753config MTRR_SANITIZER 1754 def_bool y 1755 prompt "MTRR cleanup support" 1756 depends on MTRR 1757 help 1758 Convert MTRR layout from continuous to discrete, so X drivers can 1759 add writeback entries. 1760 1761 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1762 The largest mtrr entry size for a continuous block can be set with 1763 mtrr_chunk_size. 1764 1765 If unsure, say Y. 1766 1767config MTRR_SANITIZER_ENABLE_DEFAULT 1768 int "MTRR cleanup enable value (0-1)" 1769 range 0 1 1770 default "0" 1771 depends on MTRR_SANITIZER 1772 help 1773 Enable mtrr cleanup default value 1774 1775config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1776 int "MTRR cleanup spare reg num (0-7)" 1777 range 0 7 1778 default "1" 1779 depends on MTRR_SANITIZER 1780 help 1781 mtrr cleanup spare entries default, it can be changed via 1782 mtrr_spare_reg_nr=N on the kernel command line. 1783 1784config X86_PAT 1785 def_bool y 1786 prompt "x86 PAT support" if EXPERT 1787 depends on MTRR 1788 help 1789 Use PAT attributes to setup page level cache control. 1790 1791 PATs are the modern equivalents of MTRRs and are much more 1792 flexible than MTRRs. 1793 1794 Say N here if you see bootup problems (boot crash, boot hang, 1795 spontaneous reboots) or a non-working video driver. 1796 1797 If unsure, say Y. 1798 1799config ARCH_USES_PG_UNCACHED 1800 def_bool y 1801 depends on X86_PAT 1802 1803config X86_UMIP 1804 def_bool y 1805 prompt "User Mode Instruction Prevention" if EXPERT 1806 help 1807 User Mode Instruction Prevention (UMIP) is a security feature in 1808 some x86 processors. If enabled, a general protection fault is 1809 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1810 executed in user mode. These instructions unnecessarily expose 1811 information about the hardware state. 1812 1813 The vast majority of applications do not use these instructions. 1814 For the very few that do, software emulation is provided in 1815 specific cases in protected and virtual-8086 modes. Emulated 1816 results are dummy. 1817 1818config CC_HAS_IBT 1819 # GCC >= 9 and binutils >= 2.29 1820 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1821 # Clang/LLVM >= 14 1822 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1823 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1824 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1825 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1826 $(as-instr,endbr64) 1827 1828config X86_CET 1829 def_bool n 1830 help 1831 CET features configured (Shadow stack or IBT) 1832 1833config X86_KERNEL_IBT 1834 prompt "Indirect Branch Tracking" 1835 def_bool y 1836 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1837 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1838 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1839 select OBJTOOL 1840 select X86_CET 1841 help 1842 Build the kernel with support for Indirect Branch Tracking, a 1843 hardware support course-grain forward-edge Control Flow Integrity 1844 protection. It enforces that all indirect calls must land on 1845 an ENDBR instruction, as such, the compiler will instrument the 1846 code with them to make this happen. 1847 1848 In addition to building the kernel with IBT, seal all functions that 1849 are not indirect call targets, avoiding them ever becoming one. 1850 1851 This requires LTO like objtool runs and will slow down the build. It 1852 does significantly reduce the number of ENDBR instructions in the 1853 kernel image. 1854 1855config X86_INTEL_MEMORY_PROTECTION_KEYS 1856 prompt "Memory Protection Keys" 1857 def_bool y 1858 # Note: only available in 64-bit mode 1859 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1860 select ARCH_USES_HIGH_VMA_FLAGS 1861 select ARCH_HAS_PKEYS 1862 help 1863 Memory Protection Keys provides a mechanism for enforcing 1864 page-based protections, but without requiring modification of the 1865 page tables when an application changes protection domains. 1866 1867 For details, see Documentation/core-api/protection-keys.rst 1868 1869 If unsure, say y. 1870 1871choice 1872 prompt "TSX enable mode" 1873 depends on CPU_SUP_INTEL 1874 default X86_INTEL_TSX_MODE_OFF 1875 help 1876 Intel's TSX (Transactional Synchronization Extensions) feature 1877 allows to optimize locking protocols through lock elision which 1878 can lead to a noticeable performance boost. 1879 1880 On the other hand it has been shown that TSX can be exploited 1881 to form side channel attacks (e.g. TAA) and chances are there 1882 will be more of those attacks discovered in the future. 1883 1884 Therefore TSX is not enabled by default (aka tsx=off). An admin 1885 might override this decision by tsx=on the command line parameter. 1886 Even with TSX enabled, the kernel will attempt to enable the best 1887 possible TAA mitigation setting depending on the microcode available 1888 for the particular machine. 1889 1890 This option allows to set the default tsx mode between tsx=on, =off 1891 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1892 details. 1893 1894 Say off if not sure, auto if TSX is in use but it should be used on safe 1895 platforms or on if TSX is in use and the security aspect of tsx is not 1896 relevant. 1897 1898config X86_INTEL_TSX_MODE_OFF 1899 bool "off" 1900 help 1901 TSX is disabled if possible - equals to tsx=off command line parameter. 1902 1903config X86_INTEL_TSX_MODE_ON 1904 bool "on" 1905 help 1906 TSX is always enabled on TSX capable HW - equals the tsx=on command 1907 line parameter. 1908 1909config X86_INTEL_TSX_MODE_AUTO 1910 bool "auto" 1911 help 1912 TSX is enabled on TSX capable HW that is believed to be safe against 1913 side channel attacks- equals the tsx=auto command line parameter. 1914endchoice 1915 1916config X86_SGX 1917 bool "Software Guard eXtensions (SGX)" 1918 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1919 depends on CRYPTO=y 1920 depends on CRYPTO_SHA256=y 1921 select MMU_NOTIFIER 1922 select NUMA_KEEP_MEMINFO if NUMA 1923 select XARRAY_MULTI 1924 help 1925 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1926 that can be used by applications to set aside private regions of code 1927 and data, referred to as enclaves. An enclave's private memory can 1928 only be accessed by code running within the enclave. Accesses from 1929 outside the enclave, including other enclaves, are disallowed by 1930 hardware. 1931 1932 If unsure, say N. 1933 1934config X86_USER_SHADOW_STACK 1935 bool "X86 userspace shadow stack" 1936 depends on AS_WRUSS 1937 depends on X86_64 1938 select ARCH_USES_HIGH_VMA_FLAGS 1939 select X86_CET 1940 help 1941 Shadow stack protection is a hardware feature that detects function 1942 return address corruption. This helps mitigate ROP attacks. 1943 Applications must be enabled to use it, and old userspace does not 1944 get protection "for free". 1945 1946 CPUs supporting shadow stacks were first released in 2020. 1947 1948 See Documentation/arch/x86/shstk.rst for more information. 1949 1950 If unsure, say N. 1951 1952config EFI 1953 bool "EFI runtime service support" 1954 depends on ACPI 1955 select UCS2_STRING 1956 select EFI_RUNTIME_WRAPPERS 1957 select ARCH_USE_MEMREMAP_PROT 1958 select EFI_RUNTIME_MAP if KEXEC_CORE 1959 help 1960 This enables the kernel to use EFI runtime services that are 1961 available (such as the EFI variable services). 1962 1963 This option is only useful on systems that have EFI firmware. 1964 In addition, you should use the latest ELILO loader available 1965 at <http://elilo.sourceforge.net> in order to take advantage 1966 of EFI runtime services. However, even with this option, the 1967 resultant kernel should continue to boot on existing non-EFI 1968 platforms. 1969 1970config EFI_STUB 1971 bool "EFI stub support" 1972 depends on EFI 1973 select RELOCATABLE 1974 help 1975 This kernel feature allows a bzImage to be loaded directly 1976 by EFI firmware without the use of a bootloader. 1977 1978 See Documentation/admin-guide/efi-stub.rst for more information. 1979 1980config EFI_HANDOVER_PROTOCOL 1981 bool "EFI handover protocol (DEPRECATED)" 1982 depends on EFI_STUB 1983 default y 1984 help 1985 Select this in order to include support for the deprecated EFI 1986 handover protocol, which defines alternative entry points into the 1987 EFI stub. This is a practice that has no basis in the UEFI 1988 specification, and requires a priori knowledge on the part of the 1989 bootloader about Linux/x86 specific ways of passing the command line 1990 and initrd, and where in memory those assets may be loaded. 1991 1992 If in doubt, say Y. Even though the corresponding support is not 1993 present in upstream GRUB or other bootloaders, most distros build 1994 GRUB with numerous downstream patches applied, and may rely on the 1995 handover protocol as as result. 1996 1997config EFI_MIXED 1998 bool "EFI mixed-mode support" 1999 depends on EFI_STUB && X86_64 2000 help 2001 Enabling this feature allows a 64-bit kernel to be booted 2002 on a 32-bit firmware, provided that your CPU supports 64-bit 2003 mode. 2004 2005 Note that it is not possible to boot a mixed-mode enabled 2006 kernel via the EFI boot stub - a bootloader that supports 2007 the EFI handover protocol must be used. 2008 2009 If unsure, say N. 2010 2011config EFI_FAKE_MEMMAP 2012 bool "Enable EFI fake memory map" 2013 depends on EFI 2014 help 2015 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2016 this parameter, you can add arbitrary attribute to specific memory 2017 range by updating original (firmware provided) EFI memmap. This is 2018 useful for debugging of EFI memmap related feature, e.g., Address 2019 Range Mirroring feature. 2020 2021config EFI_MAX_FAKE_MEM 2022 int "maximum allowable number of ranges in efi_fake_mem boot option" 2023 depends on EFI_FAKE_MEMMAP 2024 range 1 128 2025 default 8 2026 help 2027 Maximum allowable number of ranges in efi_fake_mem boot option. 2028 Ranges can be set up to this value using comma-separated list. 2029 The default value is 8. 2030 2031config EFI_RUNTIME_MAP 2032 bool "Export EFI runtime maps to sysfs" if EXPERT 2033 depends on EFI 2034 help 2035 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2036 That memory map is required by the 2nd kernel to set up EFI virtual 2037 mappings after kexec, but can also be used for debugging purposes. 2038 2039 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2040 2041source "kernel/Kconfig.hz" 2042 2043config ARCH_SUPPORTS_KEXEC 2044 def_bool y 2045 2046config ARCH_SUPPORTS_KEXEC_FILE 2047 def_bool X86_64 2048 2049config ARCH_SELECTS_KEXEC_FILE 2050 def_bool y 2051 depends on KEXEC_FILE 2052 select HAVE_IMA_KEXEC if IMA 2053 2054config ARCH_SUPPORTS_KEXEC_PURGATORY 2055 def_bool y 2056 2057config ARCH_SUPPORTS_KEXEC_SIG 2058 def_bool y 2059 2060config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2061 def_bool y 2062 2063config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2064 def_bool y 2065 2066config ARCH_SUPPORTS_KEXEC_JUMP 2067 def_bool y 2068 2069config ARCH_SUPPORTS_CRASH_DUMP 2070 def_bool X86_64 || (X86_32 && HIGHMEM) 2071 2072config ARCH_SUPPORTS_CRASH_HOTPLUG 2073 def_bool y 2074 2075config PHYSICAL_START 2076 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2077 default "0x1000000" 2078 help 2079 This gives the physical address where the kernel is loaded. 2080 2081 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2082 bzImage will decompress itself to above physical address and 2083 run from there. Otherwise, bzImage will run from the address where 2084 it has been loaded by the boot loader and will ignore above physical 2085 address. 2086 2087 In normal kdump cases one does not have to set/change this option 2088 as now bzImage can be compiled as a completely relocatable image 2089 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2090 address. This option is mainly useful for the folks who don't want 2091 to use a bzImage for capturing the crash dump and want to use a 2092 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2093 to be specifically compiled to run from a specific memory area 2094 (normally a reserved region) and this option comes handy. 2095 2096 So if you are using bzImage for capturing the crash dump, 2097 leave the value here unchanged to 0x1000000 and set 2098 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2099 for capturing the crash dump change this value to start of 2100 the reserved region. In other words, it can be set based on 2101 the "X" value as specified in the "crashkernel=YM@XM" 2102 command line boot parameter passed to the panic-ed 2103 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2104 for more details about crash dumps. 2105 2106 Usage of bzImage for capturing the crash dump is recommended as 2107 one does not have to build two kernels. Same kernel can be used 2108 as production kernel and capture kernel. Above option should have 2109 gone away after relocatable bzImage support is introduced. But it 2110 is present because there are users out there who continue to use 2111 vmlinux for dump capture. This option should go away down the 2112 line. 2113 2114 Don't change this unless you know what you are doing. 2115 2116config RELOCATABLE 2117 bool "Build a relocatable kernel" 2118 default y 2119 help 2120 This builds a kernel image that retains relocation information 2121 so it can be loaded someplace besides the default 1MB. 2122 The relocations tend to make the kernel binary about 10% larger, 2123 but are discarded at runtime. 2124 2125 One use is for the kexec on panic case where the recovery kernel 2126 must live at a different physical address than the primary 2127 kernel. 2128 2129 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2130 it has been loaded at and the compile time physical address 2131 (CONFIG_PHYSICAL_START) is used as the minimum location. 2132 2133config RANDOMIZE_BASE 2134 bool "Randomize the address of the kernel image (KASLR)" 2135 depends on RELOCATABLE 2136 default y 2137 help 2138 In support of Kernel Address Space Layout Randomization (KASLR), 2139 this randomizes the physical address at which the kernel image 2140 is decompressed and the virtual address where the kernel 2141 image is mapped, as a security feature that deters exploit 2142 attempts relying on knowledge of the location of kernel 2143 code internals. 2144 2145 On 64-bit, the kernel physical and virtual addresses are 2146 randomized separately. The physical address will be anywhere 2147 between 16MB and the top of physical memory (up to 64TB). The 2148 virtual address will be randomized from 16MB up to 1GB (9 bits 2149 of entropy). Note that this also reduces the memory space 2150 available to kernel modules from 1.5GB to 1GB. 2151 2152 On 32-bit, the kernel physical and virtual addresses are 2153 randomized together. They will be randomized from 16MB up to 2154 512MB (8 bits of entropy). 2155 2156 Entropy is generated using the RDRAND instruction if it is 2157 supported. If RDTSC is supported, its value is mixed into 2158 the entropy pool as well. If neither RDRAND nor RDTSC are 2159 supported, then entropy is read from the i8254 timer. The 2160 usable entropy is limited by the kernel being built using 2161 2GB addressing, and that PHYSICAL_ALIGN must be at a 2162 minimum of 2MB. As a result, only 10 bits of entropy are 2163 theoretically possible, but the implementations are further 2164 limited due to memory layouts. 2165 2166 If unsure, say Y. 2167 2168# Relocation on x86 needs some additional build support 2169config X86_NEED_RELOCS 2170 def_bool y 2171 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2172 2173config PHYSICAL_ALIGN 2174 hex "Alignment value to which kernel should be aligned" 2175 default "0x200000" 2176 range 0x2000 0x1000000 if X86_32 2177 range 0x200000 0x1000000 if X86_64 2178 help 2179 This value puts the alignment restrictions on physical address 2180 where kernel is loaded and run from. Kernel is compiled for an 2181 address which meets above alignment restriction. 2182 2183 If bootloader loads the kernel at a non-aligned address and 2184 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2185 address aligned to above value and run from there. 2186 2187 If bootloader loads the kernel at a non-aligned address and 2188 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2189 load address and decompress itself to the address it has been 2190 compiled for and run from there. The address for which kernel is 2191 compiled already meets above alignment restrictions. Hence the 2192 end result is that kernel runs from a physical address meeting 2193 above alignment restrictions. 2194 2195 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2196 this value must be a multiple of 0x200000. 2197 2198 Don't change this unless you know what you are doing. 2199 2200config DYNAMIC_MEMORY_LAYOUT 2201 bool 2202 help 2203 This option makes base addresses of vmalloc and vmemmap as well as 2204 __PAGE_OFFSET movable during boot. 2205 2206config RANDOMIZE_MEMORY 2207 bool "Randomize the kernel memory sections" 2208 depends on X86_64 2209 depends on RANDOMIZE_BASE 2210 select DYNAMIC_MEMORY_LAYOUT 2211 default RANDOMIZE_BASE 2212 help 2213 Randomizes the base virtual address of kernel memory sections 2214 (physical memory mapping, vmalloc & vmemmap). This security feature 2215 makes exploits relying on predictable memory locations less reliable. 2216 2217 The order of allocations remains unchanged. Entropy is generated in 2218 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2219 configuration have in average 30,000 different possible virtual 2220 addresses for each memory section. 2221 2222 If unsure, say Y. 2223 2224config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2225 hex "Physical memory mapping padding" if EXPERT 2226 depends on RANDOMIZE_MEMORY 2227 default "0xa" if MEMORY_HOTPLUG 2228 default "0x0" 2229 range 0x1 0x40 if MEMORY_HOTPLUG 2230 range 0x0 0x40 2231 help 2232 Define the padding in terabytes added to the existing physical 2233 memory size during kernel memory randomization. It is useful 2234 for memory hotplug support but reduces the entropy available for 2235 address randomization. 2236 2237 If unsure, leave at the default value. 2238 2239config ADDRESS_MASKING 2240 bool "Linear Address Masking support" 2241 depends on X86_64 2242 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2243 help 2244 Linear Address Masking (LAM) modifies the checking that is applied 2245 to 64-bit linear addresses, allowing software to use of the 2246 untranslated address bits for metadata. 2247 2248 The capability can be used for efficient address sanitizers (ASAN) 2249 implementation and for optimizations in JITs. 2250 2251config HOTPLUG_CPU 2252 def_bool y 2253 depends on SMP 2254 2255config COMPAT_VDSO 2256 def_bool n 2257 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2258 depends on COMPAT_32 2259 help 2260 Certain buggy versions of glibc will crash if they are 2261 presented with a 32-bit vDSO that is not mapped at the address 2262 indicated in its segment table. 2263 2264 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2265 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2266 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2267 the only released version with the bug, but OpenSUSE 9 2268 contains a buggy "glibc 2.3.2". 2269 2270 The symptom of the bug is that everything crashes on startup, saying: 2271 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2272 2273 Saying Y here changes the default value of the vdso32 boot 2274 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2275 This works around the glibc bug but hurts performance. 2276 2277 If unsure, say N: if you are compiling your own kernel, you 2278 are unlikely to be using a buggy version of glibc. 2279 2280choice 2281 prompt "vsyscall table for legacy applications" 2282 depends on X86_64 2283 default LEGACY_VSYSCALL_XONLY 2284 help 2285 Legacy user code that does not know how to find the vDSO expects 2286 to be able to issue three syscalls by calling fixed addresses in 2287 kernel space. Since this location is not randomized with ASLR, 2288 it can be used to assist security vulnerability exploitation. 2289 2290 This setting can be changed at boot time via the kernel command 2291 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2292 is deprecated and can only be enabled using the kernel command 2293 line. 2294 2295 On a system with recent enough glibc (2.14 or newer) and no 2296 static binaries, you can say None without a performance penalty 2297 to improve security. 2298 2299 If unsure, select "Emulate execution only". 2300 2301 config LEGACY_VSYSCALL_XONLY 2302 bool "Emulate execution only" 2303 help 2304 The kernel traps and emulates calls into the fixed vsyscall 2305 address mapping and does not allow reads. This 2306 configuration is recommended when userspace might use the 2307 legacy vsyscall area but support for legacy binary 2308 instrumentation of legacy code is not needed. It mitigates 2309 certain uses of the vsyscall area as an ASLR-bypassing 2310 buffer. 2311 2312 config LEGACY_VSYSCALL_NONE 2313 bool "None" 2314 help 2315 There will be no vsyscall mapping at all. This will 2316 eliminate any risk of ASLR bypass due to the vsyscall 2317 fixed address mapping. Attempts to use the vsyscalls 2318 will be reported to dmesg, so that either old or 2319 malicious userspace programs can be identified. 2320 2321endchoice 2322 2323config CMDLINE_BOOL 2324 bool "Built-in kernel command line" 2325 help 2326 Allow for specifying boot arguments to the kernel at 2327 build time. On some systems (e.g. embedded ones), it is 2328 necessary or convenient to provide some or all of the 2329 kernel boot arguments with the kernel itself (that is, 2330 to not rely on the boot loader to provide them.) 2331 2332 To compile command line arguments into the kernel, 2333 set this option to 'Y', then fill in the 2334 boot arguments in CONFIG_CMDLINE. 2335 2336 Systems with fully functional boot loaders (i.e. non-embedded) 2337 should leave this option set to 'N'. 2338 2339config CMDLINE 2340 string "Built-in kernel command string" 2341 depends on CMDLINE_BOOL 2342 default "" 2343 help 2344 Enter arguments here that should be compiled into the kernel 2345 image and used at boot time. If the boot loader provides a 2346 command line at boot time, it is appended to this string to 2347 form the full kernel command line, when the system boots. 2348 2349 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2350 change this behavior. 2351 2352 In most cases, the command line (whether built-in or provided 2353 by the boot loader) should specify the device for the root 2354 file system. 2355 2356config CMDLINE_OVERRIDE 2357 bool "Built-in command line overrides boot loader arguments" 2358 depends on CMDLINE_BOOL && CMDLINE != "" 2359 help 2360 Set this option to 'Y' to have the kernel ignore the boot loader 2361 command line, and use ONLY the built-in command line. 2362 2363 This is used to work around broken boot loaders. This should 2364 be set to 'N' under normal conditions. 2365 2366config MODIFY_LDT_SYSCALL 2367 bool "Enable the LDT (local descriptor table)" if EXPERT 2368 default y 2369 help 2370 Linux can allow user programs to install a per-process x86 2371 Local Descriptor Table (LDT) using the modify_ldt(2) system 2372 call. This is required to run 16-bit or segmented code such as 2373 DOSEMU or some Wine programs. It is also used by some very old 2374 threading libraries. 2375 2376 Enabling this feature adds a small amount of overhead to 2377 context switches and increases the low-level kernel attack 2378 surface. Disabling it removes the modify_ldt(2) system call. 2379 2380 Saying 'N' here may make sense for embedded or server kernels. 2381 2382config STRICT_SIGALTSTACK_SIZE 2383 bool "Enforce strict size checking for sigaltstack" 2384 depends on DYNAMIC_SIGFRAME 2385 help 2386 For historical reasons MINSIGSTKSZ is a constant which became 2387 already too small with AVX512 support. Add a mechanism to 2388 enforce strict checking of the sigaltstack size against the 2389 real size of the FPU frame. This option enables the check 2390 by default. It can also be controlled via the kernel command 2391 line option 'strict_sas_size' independent of this config 2392 switch. Enabling it might break existing applications which 2393 allocate a too small sigaltstack but 'work' because they 2394 never get a signal delivered. 2395 2396 Say 'N' unless you want to really enforce this check. 2397 2398source "kernel/livepatch/Kconfig" 2399 2400endmenu 2401 2402config CC_HAS_SLS 2403 def_bool $(cc-option,-mharden-sls=all) 2404 2405config CC_HAS_RETURN_THUNK 2406 def_bool $(cc-option,-mfunction-return=thunk-extern) 2407 2408config CC_HAS_ENTRY_PADDING 2409 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2410 2411config FUNCTION_PADDING_CFI 2412 int 2413 default 59 if FUNCTION_ALIGNMENT_64B 2414 default 27 if FUNCTION_ALIGNMENT_32B 2415 default 11 if FUNCTION_ALIGNMENT_16B 2416 default 3 if FUNCTION_ALIGNMENT_8B 2417 default 0 2418 2419# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2420# except Kconfig can't do arithmetic :/ 2421config FUNCTION_PADDING_BYTES 2422 int 2423 default FUNCTION_PADDING_CFI if CFI_CLANG 2424 default FUNCTION_ALIGNMENT 2425 2426config CALL_PADDING 2427 def_bool n 2428 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2429 select FUNCTION_ALIGNMENT_16B 2430 2431config FINEIBT 2432 def_bool y 2433 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE 2434 select CALL_PADDING 2435 2436config HAVE_CALL_THUNKS 2437 def_bool y 2438 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL 2439 2440config CALL_THUNKS 2441 def_bool n 2442 select CALL_PADDING 2443 2444config PREFIX_SYMBOLS 2445 def_bool y 2446 depends on CALL_PADDING && !CFI_CLANG 2447 2448menuconfig CPU_MITIGATIONS 2449 bool "Mitigations for CPU vulnerabilities" 2450 default y 2451 help 2452 Say Y here to enable options which enable mitigations for hardware 2453 vulnerabilities (usually related to speculative execution). 2454 Mitigations can be disabled or restricted to SMT systems at runtime 2455 via the "mitigations" kernel parameter. 2456 2457 If you say N, all mitigations will be disabled. This CANNOT be 2458 overridden at runtime. 2459 2460 Say 'Y', unless you really know what you are doing. 2461 2462if CPU_MITIGATIONS 2463 2464config PAGE_TABLE_ISOLATION 2465 bool "Remove the kernel mapping in user mode" 2466 default y 2467 depends on (X86_64 || X86_PAE) 2468 help 2469 This feature reduces the number of hardware side channels by 2470 ensuring that the majority of kernel addresses are not mapped 2471 into userspace. 2472 2473 See Documentation/arch/x86/pti.rst for more details. 2474 2475config RETPOLINE 2476 bool "Avoid speculative indirect branches in kernel" 2477 select OBJTOOL if HAVE_OBJTOOL 2478 default y 2479 help 2480 Compile kernel with the retpoline compiler options to guard against 2481 kernel-to-user data leaks by avoiding speculative indirect 2482 branches. Requires a compiler with -mindirect-branch=thunk-extern 2483 support for full protection. The kernel may run slower. 2484 2485config RETHUNK 2486 bool "Enable return-thunks" 2487 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2488 select OBJTOOL if HAVE_OBJTOOL 2489 default y if X86_64 2490 help 2491 Compile the kernel with the return-thunks compiler option to guard 2492 against kernel-to-user data leaks by avoiding return speculation. 2493 Requires a compiler with -mfunction-return=thunk-extern 2494 support for full protection. The kernel may run slower. 2495 2496config CPU_UNRET_ENTRY 2497 bool "Enable UNRET on kernel entry" 2498 depends on CPU_SUP_AMD && RETHUNK && X86_64 2499 default y 2500 help 2501 Compile the kernel with support for the retbleed=unret mitigation. 2502 2503config CALL_DEPTH_TRACKING 2504 bool "Mitigate RSB underflow with call depth tracking" 2505 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2506 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2507 select CALL_THUNKS 2508 default y 2509 help 2510 Compile the kernel with call depth tracking to mitigate the Intel 2511 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2512 mitigation is off by default and needs to be enabled on the 2513 kernel command line via the retbleed=stuff option. For 2514 non-affected systems the overhead of this option is marginal as 2515 the call depth tracking is using run-time generated call thunks 2516 in a compiler generated padding area and call patching. This 2517 increases text size by ~5%. For non affected systems this space 2518 is unused. On affected SKL systems this results in a significant 2519 performance gain over the IBRS mitigation. 2520 2521config CALL_THUNKS_DEBUG 2522 bool "Enable call thunks and call depth tracking debugging" 2523 depends on CALL_DEPTH_TRACKING 2524 select FUNCTION_ALIGNMENT_32B 2525 default n 2526 help 2527 Enable call/ret counters for imbalance detection and build in 2528 a noisy dmesg about callthunks generation and call patching for 2529 trouble shooting. The debug prints need to be enabled on the 2530 kernel command line with 'debug-callthunks'. 2531 Only enable this when you are debugging call thunks as this 2532 creates a noticeable runtime overhead. If unsure say N. 2533 2534config CPU_IBPB_ENTRY 2535 bool "Enable IBPB on kernel entry" 2536 depends on CPU_SUP_AMD && X86_64 2537 default y 2538 help 2539 Compile the kernel with support for the retbleed=ibpb and 2540 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations. 2541 2542config CPU_IBRS_ENTRY 2543 bool "Enable IBRS on kernel entry" 2544 depends on CPU_SUP_INTEL && X86_64 2545 default y 2546 help 2547 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2548 This mitigates both spectre_v2 and retbleed at great cost to 2549 performance. 2550 2551config CPU_SRSO 2552 bool "Mitigate speculative RAS overflow on AMD" 2553 depends on CPU_SUP_AMD && X86_64 && RETHUNK 2554 default y 2555 help 2556 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2557 2558config SLS 2559 bool "Mitigate Straight-Line-Speculation" 2560 depends on CC_HAS_SLS && X86_64 2561 select OBJTOOL if HAVE_OBJTOOL 2562 default n 2563 help 2564 Compile the kernel with straight-line-speculation options to guard 2565 against straight line speculation. The kernel image might be slightly 2566 larger. 2567 2568config GDS_FORCE_MITIGATION 2569 bool "Force GDS Mitigation" 2570 depends on CPU_SUP_INTEL 2571 default n 2572 help 2573 Gather Data Sampling (GDS) is a hardware vulnerability which allows 2574 unprivileged speculative access to data which was previously stored in 2575 vector registers. 2576 2577 This option is equivalent to setting gather_data_sampling=force on the 2578 command line. The microcode mitigation is used if present, otherwise 2579 AVX is disabled as a mitigation. On affected systems that are missing 2580 the microcode any userspace code that unconditionally uses AVX will 2581 break with this option set. 2582 2583 Setting this option on systems not vulnerable to GDS has no effect. 2584 2585 If in doubt, say N. 2586 2587config MITIGATION_RFDS 2588 bool "RFDS Mitigation" 2589 depends on CPU_SUP_INTEL 2590 default y 2591 help 2592 Enable mitigation for Register File Data Sampling (RFDS) by default. 2593 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2594 allows unprivileged speculative access to stale data previously 2595 stored in floating point, vector and integer registers. 2596 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2597 2598config MITIGATION_SPECTRE_BHI 2599 bool "Mitigate Spectre-BHB (Branch History Injection)" 2600 depends on CPU_SUP_INTEL 2601 default y 2602 help 2603 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2604 where the branch history buffer is poisoned to speculatively steer 2605 indirect branches. 2606 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2607 2608endif 2609 2610config ARCH_HAS_ADD_PAGES 2611 def_bool y 2612 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2613 2614menu "Power management and ACPI options" 2615 2616config ARCH_HIBERNATION_HEADER 2617 def_bool y 2618 depends on HIBERNATION 2619 2620source "kernel/power/Kconfig" 2621 2622source "drivers/acpi/Kconfig" 2623 2624config X86_APM_BOOT 2625 def_bool y 2626 depends on APM 2627 2628menuconfig APM 2629 tristate "APM (Advanced Power Management) BIOS support" 2630 depends on X86_32 && PM_SLEEP 2631 help 2632 APM is a BIOS specification for saving power using several different 2633 techniques. This is mostly useful for battery powered laptops with 2634 APM compliant BIOSes. If you say Y here, the system time will be 2635 reset after a RESUME operation, the /proc/apm device will provide 2636 battery status information, and user-space programs will receive 2637 notification of APM "events" (e.g. battery status change). 2638 2639 If you select "Y" here, you can disable actual use of the APM 2640 BIOS by passing the "apm=off" option to the kernel at boot time. 2641 2642 Note that the APM support is almost completely disabled for 2643 machines with more than one CPU. 2644 2645 In order to use APM, you will need supporting software. For location 2646 and more information, read <file:Documentation/power/apm-acpi.rst> 2647 and the Battery Powered Linux mini-HOWTO, available from 2648 <http://www.tldp.org/docs.html#howto>. 2649 2650 This driver does not spin down disk drives (see the hdparm(8) 2651 manpage ("man 8 hdparm") for that), and it doesn't turn off 2652 VESA-compliant "green" monitors. 2653 2654 This driver does not support the TI 4000M TravelMate and the ACER 2655 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2656 desktop machines also don't have compliant BIOSes, and this driver 2657 may cause those machines to panic during the boot phase. 2658 2659 Generally, if you don't have a battery in your machine, there isn't 2660 much point in using this driver and you should say N. If you get 2661 random kernel OOPSes or reboots that don't seem to be related to 2662 anything, try disabling/enabling this option (or disabling/enabling 2663 APM in your BIOS). 2664 2665 Some other things you should try when experiencing seemingly random, 2666 "weird" problems: 2667 2668 1) make sure that you have enough swap space and that it is 2669 enabled. 2670 2) pass the "idle=poll" option to the kernel 2671 3) switch on floating point emulation in the kernel and pass 2672 the "no387" option to the kernel 2673 4) pass the "floppy=nodma" option to the kernel 2674 5) pass the "mem=4M" option to the kernel (thereby disabling 2675 all but the first 4 MB of RAM) 2676 6) make sure that the CPU is not over clocked. 2677 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2678 8) disable the cache from your BIOS settings 2679 9) install a fan for the video card or exchange video RAM 2680 10) install a better fan for the CPU 2681 11) exchange RAM chips 2682 12) exchange the motherboard. 2683 2684 To compile this driver as a module, choose M here: the 2685 module will be called apm. 2686 2687if APM 2688 2689config APM_IGNORE_USER_SUSPEND 2690 bool "Ignore USER SUSPEND" 2691 help 2692 This option will ignore USER SUSPEND requests. On machines with a 2693 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2694 series notebooks, it is necessary to say Y because of a BIOS bug. 2695 2696config APM_DO_ENABLE 2697 bool "Enable PM at boot time" 2698 help 2699 Enable APM features at boot time. From page 36 of the APM BIOS 2700 specification: "When disabled, the APM BIOS does not automatically 2701 power manage devices, enter the Standby State, enter the Suspend 2702 State, or take power saving steps in response to CPU Idle calls." 2703 This driver will make CPU Idle calls when Linux is idle (unless this 2704 feature is turned off -- see "Do CPU IDLE calls", below). This 2705 should always save battery power, but more complicated APM features 2706 will be dependent on your BIOS implementation. You may need to turn 2707 this option off if your computer hangs at boot time when using APM 2708 support, or if it beeps continuously instead of suspending. Turn 2709 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2710 T400CDT. This is off by default since most machines do fine without 2711 this feature. 2712 2713config APM_CPU_IDLE 2714 depends on CPU_IDLE 2715 bool "Make CPU Idle calls when idle" 2716 help 2717 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2718 On some machines, this can activate improved power savings, such as 2719 a slowed CPU clock rate, when the machine is idle. These idle calls 2720 are made after the idle loop has run for some length of time (e.g., 2721 333 mS). On some machines, this will cause a hang at boot time or 2722 whenever the CPU becomes idle. (On machines with more than one CPU, 2723 this option does nothing.) 2724 2725config APM_DISPLAY_BLANK 2726 bool "Enable console blanking using APM" 2727 help 2728 Enable console blanking using the APM. Some laptops can use this to 2729 turn off the LCD backlight when the screen blanker of the Linux 2730 virtual console blanks the screen. Note that this is only used by 2731 the virtual console screen blanker, and won't turn off the backlight 2732 when using the X Window system. This also doesn't have anything to 2733 do with your VESA-compliant power-saving monitor. Further, this 2734 option doesn't work for all laptops -- it might not turn off your 2735 backlight at all, or it might print a lot of errors to the console, 2736 especially if you are using gpm. 2737 2738config APM_ALLOW_INTS 2739 bool "Allow interrupts during APM BIOS calls" 2740 help 2741 Normally we disable external interrupts while we are making calls to 2742 the APM BIOS as a measure to lessen the effects of a badly behaving 2743 BIOS implementation. The BIOS should reenable interrupts if it 2744 needs to. Unfortunately, some BIOSes do not -- especially those in 2745 many of the newer IBM Thinkpads. If you experience hangs when you 2746 suspend, try setting this to Y. Otherwise, say N. 2747 2748endif # APM 2749 2750source "drivers/cpufreq/Kconfig" 2751 2752source "drivers/cpuidle/Kconfig" 2753 2754source "drivers/idle/Kconfig" 2755 2756endmenu 2757 2758menu "Bus options (PCI etc.)" 2759 2760choice 2761 prompt "PCI access mode" 2762 depends on X86_32 && PCI 2763 default PCI_GOANY 2764 help 2765 On PCI systems, the BIOS can be used to detect the PCI devices and 2766 determine their configuration. However, some old PCI motherboards 2767 have BIOS bugs and may crash if this is done. Also, some embedded 2768 PCI-based systems don't have any BIOS at all. Linux can also try to 2769 detect the PCI hardware directly without using the BIOS. 2770 2771 With this option, you can specify how Linux should detect the 2772 PCI devices. If you choose "BIOS", the BIOS will be used, 2773 if you choose "Direct", the BIOS won't be used, and if you 2774 choose "MMConfig", then PCI Express MMCONFIG will be used. 2775 If you choose "Any", the kernel will try MMCONFIG, then the 2776 direct access method and falls back to the BIOS if that doesn't 2777 work. If unsure, go with the default, which is "Any". 2778 2779config PCI_GOBIOS 2780 bool "BIOS" 2781 2782config PCI_GOMMCONFIG 2783 bool "MMConfig" 2784 2785config PCI_GODIRECT 2786 bool "Direct" 2787 2788config PCI_GOOLPC 2789 bool "OLPC XO-1" 2790 depends on OLPC 2791 2792config PCI_GOANY 2793 bool "Any" 2794 2795endchoice 2796 2797config PCI_BIOS 2798 def_bool y 2799 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2800 2801# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2802config PCI_DIRECT 2803 def_bool y 2804 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2805 2806config PCI_MMCONFIG 2807 bool "Support mmconfig PCI config space access" if X86_64 2808 default y 2809 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2810 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2811 2812config PCI_OLPC 2813 def_bool y 2814 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2815 2816config PCI_XEN 2817 def_bool y 2818 depends on PCI && XEN 2819 2820config MMCONF_FAM10H 2821 def_bool y 2822 depends on X86_64 && PCI_MMCONFIG && ACPI 2823 2824config PCI_CNB20LE_QUIRK 2825 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2826 depends on PCI 2827 help 2828 Read the PCI windows out of the CNB20LE host bridge. This allows 2829 PCI hotplug to work on systems with the CNB20LE chipset which do 2830 not have ACPI. 2831 2832 There's no public spec for this chipset, and this functionality 2833 is known to be incomplete. 2834 2835 You should say N unless you know you need this. 2836 2837config ISA_BUS 2838 bool "ISA bus support on modern systems" if EXPERT 2839 help 2840 Expose ISA bus device drivers and options available for selection and 2841 configuration. Enable this option if your target machine has an ISA 2842 bus. ISA is an older system, displaced by PCI and newer bus 2843 architectures -- if your target machine is modern, it probably does 2844 not have an ISA bus. 2845 2846 If unsure, say N. 2847 2848# x86_64 have no ISA slots, but can have ISA-style DMA. 2849config ISA_DMA_API 2850 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2851 default y 2852 help 2853 Enables ISA-style DMA support for devices requiring such controllers. 2854 If unsure, say Y. 2855 2856if X86_32 2857 2858config ISA 2859 bool "ISA support" 2860 help 2861 Find out whether you have ISA slots on your motherboard. ISA is the 2862 name of a bus system, i.e. the way the CPU talks to the other stuff 2863 inside your box. Other bus systems are PCI, EISA, MicroChannel 2864 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2865 newer boards don't support it. If you have ISA, say Y, otherwise N. 2866 2867config SCx200 2868 tristate "NatSemi SCx200 support" 2869 help 2870 This provides basic support for National Semiconductor's 2871 (now AMD's) Geode processors. The driver probes for the 2872 PCI-IDs of several on-chip devices, so its a good dependency 2873 for other scx200_* drivers. 2874 2875 If compiled as a module, the driver is named scx200. 2876 2877config SCx200HR_TIMER 2878 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2879 depends on SCx200 2880 default y 2881 help 2882 This driver provides a clocksource built upon the on-chip 2883 27MHz high-resolution timer. Its also a workaround for 2884 NSC Geode SC-1100's buggy TSC, which loses time when the 2885 processor goes idle (as is done by the scheduler). The 2886 other workaround is idle=poll boot option. 2887 2888config OLPC 2889 bool "One Laptop Per Child support" 2890 depends on !X86_PAE 2891 select GPIOLIB 2892 select OF 2893 select OF_PROMTREE 2894 select IRQ_DOMAIN 2895 select OLPC_EC 2896 help 2897 Add support for detecting the unique features of the OLPC 2898 XO hardware. 2899 2900config OLPC_XO1_PM 2901 bool "OLPC XO-1 Power Management" 2902 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2903 help 2904 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2905 2906config OLPC_XO1_RTC 2907 bool "OLPC XO-1 Real Time Clock" 2908 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2909 help 2910 Add support for the XO-1 real time clock, which can be used as a 2911 programmable wakeup source. 2912 2913config OLPC_XO1_SCI 2914 bool "OLPC XO-1 SCI extras" 2915 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2916 depends on INPUT=y 2917 select POWER_SUPPLY 2918 help 2919 Add support for SCI-based features of the OLPC XO-1 laptop: 2920 - EC-driven system wakeups 2921 - Power button 2922 - Ebook switch 2923 - Lid switch 2924 - AC adapter status updates 2925 - Battery status updates 2926 2927config OLPC_XO15_SCI 2928 bool "OLPC XO-1.5 SCI extras" 2929 depends on OLPC && ACPI 2930 select POWER_SUPPLY 2931 help 2932 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2933 - EC-driven system wakeups 2934 - AC adapter status updates 2935 - Battery status updates 2936 2937config ALIX 2938 bool "PCEngines ALIX System Support (LED setup)" 2939 select GPIOLIB 2940 help 2941 This option enables system support for the PCEngines ALIX. 2942 At present this just sets up LEDs for GPIO control on 2943 ALIX2/3/6 boards. However, other system specific setup should 2944 get added here. 2945 2946 Note: You must still enable the drivers for GPIO and LED support 2947 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2948 2949 Note: You have to set alix.force=1 for boards with Award BIOS. 2950 2951config NET5501 2952 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2953 select GPIOLIB 2954 help 2955 This option enables system support for the Soekris Engineering net5501. 2956 2957config GEOS 2958 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2959 select GPIOLIB 2960 depends on DMI 2961 help 2962 This option enables system support for the Traverse Technologies GEOS. 2963 2964config TS5500 2965 bool "Technologic Systems TS-5500 platform support" 2966 depends on MELAN 2967 select CHECK_SIGNATURE 2968 select NEW_LEDS 2969 select LEDS_CLASS 2970 help 2971 This option enables system support for the Technologic Systems TS-5500. 2972 2973endif # X86_32 2974 2975config AMD_NB 2976 def_bool y 2977 depends on CPU_SUP_AMD && PCI 2978 2979endmenu 2980 2981menu "Binary Emulations" 2982 2983config IA32_EMULATION 2984 bool "IA32 Emulation" 2985 depends on X86_64 2986 select ARCH_WANT_OLD_COMPAT_IPC 2987 select BINFMT_ELF 2988 select COMPAT_OLD_SIGACTION 2989 help 2990 Include code to run legacy 32-bit programs under a 2991 64-bit kernel. You should likely turn this on, unless you're 2992 100% sure that you don't have any 32-bit programs left. 2993 2994config X86_X32_ABI 2995 bool "x32 ABI for 64-bit mode" 2996 depends on X86_64 2997 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2998 # compressed debug sections to x86_x32 properly: 2999 # https://github.com/ClangBuiltLinux/linux/issues/514 3000 # https://github.com/ClangBuiltLinux/linux/issues/1141 3001 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3002 help 3003 Include code to run binaries for the x32 native 32-bit ABI 3004 for 64-bit processors. An x32 process gets access to the 3005 full 64-bit register file and wide data path while leaving 3006 pointers at 32 bits for smaller memory footprint. 3007 3008config COMPAT_32 3009 def_bool y 3010 depends on IA32_EMULATION || X86_32 3011 select HAVE_UID16 3012 select OLD_SIGSUSPEND3 3013 3014config COMPAT 3015 def_bool y 3016 depends on IA32_EMULATION || X86_X32_ABI 3017 3018config COMPAT_FOR_U64_ALIGNMENT 3019 def_bool y 3020 depends on COMPAT 3021 3022endmenu 3023 3024config HAVE_ATOMIC_IOMAP 3025 def_bool y 3026 depends on X86_32 3027 3028source "arch/x86/kvm/Kconfig" 3029 3030source "arch/x86/Kconfig.assembler" 3031