1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select ARCH_USE_CMPXCHG_LOCKREF 32 select HAVE_ARCH_SOFT_DIRTY 33 select MODULES_USE_ELF_RELA 34 select NEED_DMA_MAP_STATE 35 select SWIOTLB 36 select ARCH_HAS_ELFCORE_COMPAT 37 select ZONE_DMA32 38 39config FORCE_DYNAMIC_FTRACE 40 def_bool y 41 depends on X86_32 42 depends on FUNCTION_TRACER 43 select DYNAMIC_FTRACE 44 help 45 We keep the static function tracing (!DYNAMIC_FTRACE) around 46 in order to test the non static function tracing in the 47 generic code, as other architectures still use it. But we 48 only need to keep it around for x86_64. No need to keep it 49 for x86_32. For x86_32, force DYNAMIC_FTRACE. 50# 51# Arch settings 52# 53# ( Note that options that are marked 'if X86_64' could in principle be 54# ported to 32-bit as well. ) 55# 56config X86 57 def_bool y 58 # 59 # Note: keep this list sorted alphabetically 60 # 61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 63 select ARCH_32BIT_OFF_T if X86_32 64 select ARCH_CLOCKSOURCE_INIT 65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 72 select ARCH_HAS_CACHE_LINE_SIZE 73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 74 select ARCH_HAS_CPU_FINALIZE_INIT 75 select ARCH_HAS_CURRENT_STACK_POINTER 76 select ARCH_HAS_DEBUG_VIRTUAL 77 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 78 select ARCH_HAS_DEVMEM_IS_ALLOWED 79 select ARCH_HAS_EARLY_DEBUG if KGDB 80 select ARCH_HAS_ELF_RANDOMIZE 81 select ARCH_HAS_FAST_MULTIPLIER 82 select ARCH_HAS_FORTIFY_SOURCE 83 select ARCH_HAS_GCOV_PROFILE_ALL 84 select ARCH_HAS_KCOV if X86_64 85 select ARCH_HAS_MEM_ENCRYPT 86 select ARCH_HAS_MEMBARRIER_SYNC_CORE 87 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 88 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 89 select ARCH_HAS_PMEM_API if X86_64 90 select ARCH_HAS_PTE_DEVMAP if X86_64 91 select ARCH_HAS_PTE_SPECIAL 92 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 93 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 94 select ARCH_HAS_COPY_MC if X86_64 95 select ARCH_HAS_SET_MEMORY 96 select ARCH_HAS_SET_DIRECT_MAP 97 select ARCH_HAS_STRICT_KERNEL_RWX 98 select ARCH_HAS_STRICT_MODULE_RWX 99 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 100 select ARCH_HAS_SYSCALL_WRAPPER 101 select ARCH_HAS_UBSAN_SANITIZE_ALL 102 select ARCH_HAS_DEBUG_WX 103 select ARCH_HAS_ZONE_DMA_SET if EXPERT 104 select ARCH_HAVE_NMI_SAFE_CMPXCHG 105 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 106 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 107 select ARCH_MIGHT_HAVE_PC_PARPORT 108 select ARCH_MIGHT_HAVE_PC_SERIO 109 select ARCH_STACKWALK 110 select ARCH_SUPPORTS_ACPI 111 select ARCH_SUPPORTS_ATOMIC_RMW 112 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 113 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 114 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 115 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 116 select ARCH_SUPPORTS_CFI_CLANG if X86_64 117 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 118 select ARCH_SUPPORTS_LTO_CLANG 119 select ARCH_SUPPORTS_LTO_CLANG_THIN 120 select ARCH_USE_BUILTIN_BSWAP 121 select ARCH_USE_MEMTEST 122 select ARCH_USE_QUEUED_RWLOCKS 123 select ARCH_USE_QUEUED_SPINLOCKS 124 select ARCH_USE_SYM_ANNOTATIONS 125 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 126 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 127 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 128 select ARCH_WANTS_NO_INSTR 129 select ARCH_WANT_GENERAL_HUGETLB 130 select ARCH_WANT_HUGE_PMD_SHARE 131 select ARCH_WANT_LD_ORPHAN_WARN 132 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 133 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 134 select ARCH_WANTS_THP_SWAP if X86_64 135 select ARCH_HAS_PARANOID_L1D_FLUSH 136 select BUILDTIME_TABLE_SORT 137 select CLKEVT_I8253 138 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 139 select CLOCKSOURCE_WATCHDOG 140 # Word-size accesses may read uninitialized data past the trailing \0 141 # in strings and cause false KMSAN reports. 142 select DCACHE_WORD_ACCESS if !KMSAN 143 select DYNAMIC_SIGFRAME 144 select EDAC_ATOMIC_SCRUB 145 select EDAC_SUPPORT 146 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 147 select GENERIC_CLOCKEVENTS_MIN_ADJUST 148 select GENERIC_CMOS_UPDATE 149 select GENERIC_CPU_AUTOPROBE 150 select GENERIC_CPU_VULNERABILITIES 151 select GENERIC_EARLY_IOREMAP 152 select GENERIC_ENTRY 153 select GENERIC_IOMAP 154 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 155 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 156 select GENERIC_IRQ_MIGRATION if SMP 157 select GENERIC_IRQ_PROBE 158 select GENERIC_IRQ_RESERVATION_MODE 159 select GENERIC_IRQ_SHOW 160 select GENERIC_PENDING_IRQ if SMP 161 select GENERIC_PTDUMP 162 select GENERIC_SMP_IDLE_THREAD 163 select GENERIC_TIME_VSYSCALL 164 select GENERIC_GETTIMEOFDAY 165 select GENERIC_VDSO_TIME_NS 166 select GUP_GET_PXX_LOW_HIGH if X86_PAE 167 select HARDIRQS_SW_RESEND 168 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 169 select HAS_IOPORT 170 select HAVE_ACPI_APEI if ACPI 171 select HAVE_ACPI_APEI_NMI if ACPI 172 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 173 select HAVE_ARCH_AUDITSYSCALL 174 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 175 select HAVE_ARCH_HUGE_VMALLOC if X86_64 176 select HAVE_ARCH_JUMP_LABEL 177 select HAVE_ARCH_JUMP_LABEL_RELATIVE 178 select HAVE_ARCH_KASAN if X86_64 179 select HAVE_ARCH_KASAN_VMALLOC if X86_64 180 select HAVE_ARCH_KFENCE 181 select HAVE_ARCH_KMSAN if X86_64 182 select HAVE_ARCH_KGDB 183 select HAVE_ARCH_MMAP_RND_BITS if MMU 184 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 185 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 186 select HAVE_ARCH_PREL32_RELOCATIONS 187 select HAVE_ARCH_SECCOMP_FILTER 188 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 189 select HAVE_ARCH_STACKLEAK 190 select HAVE_ARCH_TRACEHOOK 191 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 192 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 193 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 194 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 195 select HAVE_ARCH_VMAP_STACK if X86_64 196 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 197 select HAVE_ARCH_WITHIN_STACK_FRAMES 198 select HAVE_ASM_MODVERSIONS 199 select HAVE_CMPXCHG_DOUBLE 200 select HAVE_CMPXCHG_LOCAL 201 select HAVE_CONTEXT_TRACKING_USER if X86_64 202 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 203 select HAVE_C_RECORDMCOUNT 204 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 205 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 206 select HAVE_BUILDTIME_MCOUNT_SORT 207 select HAVE_DEBUG_KMEMLEAK 208 select HAVE_DMA_CONTIGUOUS 209 select HAVE_DYNAMIC_FTRACE 210 select HAVE_DYNAMIC_FTRACE_WITH_REGS 211 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 212 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 213 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 214 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 215 select HAVE_EBPF_JIT 216 select HAVE_EFFICIENT_UNALIGNED_ACCESS 217 select HAVE_EISA 218 select HAVE_EXIT_THREAD 219 select HAVE_FAST_GUP 220 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 221 select HAVE_FTRACE_MCOUNT_RECORD 222 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 223 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 224 select HAVE_FUNCTION_TRACER 225 select HAVE_GCC_PLUGINS 226 select HAVE_HW_BREAKPOINT 227 select HAVE_IOREMAP_PROT 228 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 229 select HAVE_IRQ_TIME_ACCOUNTING 230 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 231 select HAVE_KERNEL_BZIP2 232 select HAVE_KERNEL_GZIP 233 select HAVE_KERNEL_LZ4 234 select HAVE_KERNEL_LZMA 235 select HAVE_KERNEL_LZO 236 select HAVE_KERNEL_XZ 237 select HAVE_KERNEL_ZSTD 238 select HAVE_KPROBES 239 select HAVE_KPROBES_ON_FTRACE 240 select HAVE_FUNCTION_ERROR_INJECTION 241 select HAVE_KRETPROBES 242 select HAVE_RETHOOK 243 select HAVE_KVM 244 select HAVE_LIVEPATCH if X86_64 245 select HAVE_MIXED_BREAKPOINTS_REGS 246 select HAVE_MOD_ARCH_SPECIFIC 247 select HAVE_MOVE_PMD 248 select HAVE_MOVE_PUD 249 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 250 select HAVE_NMI 251 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 252 select HAVE_OBJTOOL if X86_64 253 select HAVE_OPTPROBES 254 select HAVE_PCSPKR_PLATFORM 255 select HAVE_PERF_EVENTS 256 select HAVE_PERF_EVENTS_NMI 257 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 258 select HAVE_PCI 259 select HAVE_PERF_REGS 260 select HAVE_PERF_USER_STACK_DUMP 261 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 262 select MMU_GATHER_MERGE_VMAS 263 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 264 select HAVE_REGS_AND_STACK_ACCESS_API 265 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 266 select HAVE_FUNCTION_ARG_ACCESS_API 267 select HAVE_SETUP_PER_CPU_AREA 268 select HAVE_SOFTIRQ_ON_OWN_STACK 269 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 270 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 271 select HAVE_STATIC_CALL 272 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 273 select HAVE_PREEMPT_DYNAMIC_CALL 274 select HAVE_RSEQ 275 select HAVE_RUST if X86_64 276 select HAVE_SYSCALL_TRACEPOINTS 277 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 278 select HAVE_UNSTABLE_SCHED_CLOCK 279 select HAVE_USER_RETURN_NOTIFIER 280 select HAVE_GENERIC_VDSO 281 select HOTPLUG_PARALLEL if SMP && X86_64 282 select HOTPLUG_SMT if SMP 283 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 284 select IRQ_FORCED_THREADING 285 select LOCK_MM_AND_FIND_VMA 286 select NEED_PER_CPU_EMBED_FIRST_CHUNK 287 select NEED_PER_CPU_PAGE_FIRST_CHUNK 288 select NEED_SG_DMA_LENGTH 289 select PCI_DOMAINS if PCI 290 select PCI_LOCKLESS_CONFIG if PCI 291 select PERF_EVENTS 292 select RTC_LIB 293 select RTC_MC146818_LIB 294 select SPARSE_IRQ 295 select SYSCTL_EXCEPTION_TRACE 296 select THREAD_INFO_IN_TASK 297 select TRACE_IRQFLAGS_SUPPORT 298 select TRACE_IRQFLAGS_NMI_SUPPORT 299 select USER_STACKTRACE_SUPPORT 300 select HAVE_ARCH_KCSAN if X86_64 301 select PROC_PID_ARCH_STATUS if PROC_FS 302 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 303 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 304 select FUNCTION_ALIGNMENT_4B 305 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 306 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 307 308config INSTRUCTION_DECODER 309 def_bool y 310 depends on KPROBES || PERF_EVENTS || UPROBES 311 312config OUTPUT_FORMAT 313 string 314 default "elf32-i386" if X86_32 315 default "elf64-x86-64" if X86_64 316 317config LOCKDEP_SUPPORT 318 def_bool y 319 320config STACKTRACE_SUPPORT 321 def_bool y 322 323config MMU 324 def_bool y 325 326config ARCH_MMAP_RND_BITS_MIN 327 default 28 if 64BIT 328 default 8 329 330config ARCH_MMAP_RND_BITS_MAX 331 default 32 if 64BIT 332 default 16 333 334config ARCH_MMAP_RND_COMPAT_BITS_MIN 335 default 8 336 337config ARCH_MMAP_RND_COMPAT_BITS_MAX 338 default 16 339 340config SBUS 341 bool 342 343config GENERIC_ISA_DMA 344 def_bool y 345 depends on ISA_DMA_API 346 347config GENERIC_CSUM 348 bool 349 default y if KMSAN || KASAN 350 351config GENERIC_BUG 352 def_bool y 353 depends on BUG 354 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 355 356config GENERIC_BUG_RELATIVE_POINTERS 357 bool 358 359config ARCH_MAY_HAVE_PC_FDC 360 def_bool y 361 depends on ISA_DMA_API 362 363config GENERIC_CALIBRATE_DELAY 364 def_bool y 365 366config ARCH_HAS_CPU_RELAX 367 def_bool y 368 369config ARCH_HIBERNATION_POSSIBLE 370 def_bool y 371 372config ARCH_SUSPEND_POSSIBLE 373 def_bool y 374 375config AUDIT_ARCH 376 def_bool y if X86_64 377 378config KASAN_SHADOW_OFFSET 379 hex 380 depends on KASAN 381 default 0xdffffc0000000000 382 383config HAVE_INTEL_TXT 384 def_bool y 385 depends on INTEL_IOMMU && ACPI 386 387config X86_32_SMP 388 def_bool y 389 depends on X86_32 && SMP 390 391config X86_64_SMP 392 def_bool y 393 depends on X86_64 && SMP 394 395config ARCH_SUPPORTS_UPROBES 396 def_bool y 397 398config FIX_EARLYCON_MEM 399 def_bool y 400 401config DYNAMIC_PHYSICAL_MASK 402 bool 403 404config PGTABLE_LEVELS 405 int 406 default 5 if X86_5LEVEL 407 default 4 if X86_64 408 default 3 if X86_PAE 409 default 2 410 411config CC_HAS_SANE_STACKPROTECTOR 412 bool 413 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 414 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 415 help 416 We have to make sure stack protector is unconditionally disabled if 417 the compiler produces broken code or if it does not let us control 418 the segment on 32-bit kernels. 419 420menu "Processor type and features" 421 422config SMP 423 bool "Symmetric multi-processing support" 424 help 425 This enables support for systems with more than one CPU. If you have 426 a system with only one CPU, say N. If you have a system with more 427 than one CPU, say Y. 428 429 If you say N here, the kernel will run on uni- and multiprocessor 430 machines, but will use only one CPU of a multiprocessor machine. If 431 you say Y here, the kernel will run on many, but not all, 432 uniprocessor machines. On a uniprocessor machine, the kernel 433 will run faster if you say N here. 434 435 Note that if you say Y here and choose architecture "586" or 436 "Pentium" under "Processor family", the kernel will not work on 486 437 architectures. Similarly, multiprocessor kernels for the "PPro" 438 architecture may not work on all Pentium based boards. 439 440 People using multiprocessor machines who say Y here should also say 441 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 442 Management" code will be disabled if you say Y here. 443 444 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 445 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 446 <http://www.tldp.org/docs.html#howto>. 447 448 If you don't know what to do here, say N. 449 450config X86_X2APIC 451 bool "Support x2apic" 452 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 453 help 454 This enables x2apic support on CPUs that have this feature. 455 456 This allows 32-bit apic IDs (so it can support very large systems), 457 and accesses the local apic via MSRs not via mmio. 458 459 Some Intel systems circa 2022 and later are locked into x2APIC mode 460 and can not fall back to the legacy APIC modes if SGX or TDX are 461 enabled in the BIOS. They will boot with very reduced functionality 462 without enabling this option. 463 464 If you don't know what to do here, say N. 465 466config X86_MPPARSE 467 bool "Enable MPS table" if ACPI 468 default y 469 depends on X86_LOCAL_APIC 470 help 471 For old smp systems that do not have proper acpi support. Newer systems 472 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 473 474config GOLDFISH 475 def_bool y 476 depends on X86_GOLDFISH 477 478config X86_CPU_RESCTRL 479 bool "x86 CPU resource control support" 480 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 481 select KERNFS 482 select PROC_CPU_RESCTRL if PROC_FS 483 help 484 Enable x86 CPU resource control support. 485 486 Provide support for the allocation and monitoring of system resources 487 usage by the CPU. 488 489 Intel calls this Intel Resource Director Technology 490 (Intel(R) RDT). More information about RDT can be found in the 491 Intel x86 Architecture Software Developer Manual. 492 493 AMD calls this AMD Platform Quality of Service (AMD QoS). 494 More information about AMD QoS can be found in the AMD64 Technology 495 Platform Quality of Service Extensions manual. 496 497 Say N if unsure. 498 499if X86_32 500config X86_BIGSMP 501 bool "Support for big SMP systems with more than 8 CPUs" 502 depends on SMP 503 help 504 This option is needed for the systems that have more than 8 CPUs. 505 506config X86_EXTENDED_PLATFORM 507 bool "Support for extended (non-PC) x86 platforms" 508 default y 509 help 510 If you disable this option then the kernel will only support 511 standard PC platforms. (which covers the vast majority of 512 systems out there.) 513 514 If you enable this option then you'll be able to select support 515 for the following (non-PC) 32 bit x86 platforms: 516 Goldfish (Android emulator) 517 AMD Elan 518 RDC R-321x SoC 519 SGI 320/540 (Visual Workstation) 520 STA2X11-based (e.g. Northville) 521 Moorestown MID devices 522 523 If you have one of these systems, or if you want to build a 524 generic distribution kernel, say Y here - otherwise say N. 525endif # X86_32 526 527if X86_64 528config X86_EXTENDED_PLATFORM 529 bool "Support for extended (non-PC) x86 platforms" 530 default y 531 help 532 If you disable this option then the kernel will only support 533 standard PC platforms. (which covers the vast majority of 534 systems out there.) 535 536 If you enable this option then you'll be able to select support 537 for the following (non-PC) 64 bit x86 platforms: 538 Numascale NumaChip 539 ScaleMP vSMP 540 SGI Ultraviolet 541 542 If you have one of these systems, or if you want to build a 543 generic distribution kernel, say Y here - otherwise say N. 544endif # X86_64 545# This is an alphabetically sorted list of 64 bit extended platforms 546# Please maintain the alphabetic order if and when there are additions 547config X86_NUMACHIP 548 bool "Numascale NumaChip" 549 depends on X86_64 550 depends on X86_EXTENDED_PLATFORM 551 depends on NUMA 552 depends on SMP 553 depends on X86_X2APIC 554 depends on PCI_MMCONFIG 555 help 556 Adds support for Numascale NumaChip large-SMP systems. Needed to 557 enable more than ~168 cores. 558 If you don't have one of these, you should say N here. 559 560config X86_VSMP 561 bool "ScaleMP vSMP" 562 select HYPERVISOR_GUEST 563 select PARAVIRT 564 depends on X86_64 && PCI 565 depends on X86_EXTENDED_PLATFORM 566 depends on SMP 567 help 568 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 569 supposed to run on these EM64T-based machines. Only choose this option 570 if you have one of these machines. 571 572config X86_UV 573 bool "SGI Ultraviolet" 574 depends on X86_64 575 depends on X86_EXTENDED_PLATFORM 576 depends on NUMA 577 depends on EFI 578 depends on KEXEC_CORE 579 depends on X86_X2APIC 580 depends on PCI 581 help 582 This option is needed in order to support SGI Ultraviolet systems. 583 If you don't have one of these, you should say N here. 584 585# Following is an alphabetically sorted list of 32 bit extended platforms 586# Please maintain the alphabetic order if and when there are additions 587 588config X86_GOLDFISH 589 bool "Goldfish (Virtual Platform)" 590 depends on X86_EXTENDED_PLATFORM 591 help 592 Enable support for the Goldfish virtual platform used primarily 593 for Android development. Unless you are building for the Android 594 Goldfish emulator say N here. 595 596config X86_INTEL_CE 597 bool "CE4100 TV platform" 598 depends on PCI 599 depends on PCI_GODIRECT 600 depends on X86_IO_APIC 601 depends on X86_32 602 depends on X86_EXTENDED_PLATFORM 603 select X86_REBOOTFIXUPS 604 select OF 605 select OF_EARLY_FLATTREE 606 help 607 Select for the Intel CE media processor (CE4100) SOC. 608 This option compiles in support for the CE4100 SOC for settop 609 boxes and media devices. 610 611config X86_INTEL_MID 612 bool "Intel MID platform support" 613 depends on X86_EXTENDED_PLATFORM 614 depends on X86_PLATFORM_DEVICES 615 depends on PCI 616 depends on X86_64 || (PCI_GOANY && X86_32) 617 depends on X86_IO_APIC 618 select I2C 619 select DW_APB_TIMER 620 select INTEL_SCU_PCI 621 help 622 Select to build a kernel capable of supporting Intel MID (Mobile 623 Internet Device) platform systems which do not have the PCI legacy 624 interfaces. If you are building for a PC class system say N here. 625 626 Intel MID platforms are based on an Intel processor and chipset which 627 consume less power than most of the x86 derivatives. 628 629config X86_INTEL_QUARK 630 bool "Intel Quark platform support" 631 depends on X86_32 632 depends on X86_EXTENDED_PLATFORM 633 depends on X86_PLATFORM_DEVICES 634 depends on X86_TSC 635 depends on PCI 636 depends on PCI_GOANY 637 depends on X86_IO_APIC 638 select IOSF_MBI 639 select INTEL_IMR 640 select COMMON_CLK 641 help 642 Select to include support for Quark X1000 SoC. 643 Say Y here if you have a Quark based system such as the Arduino 644 compatible Intel Galileo. 645 646config X86_INTEL_LPSS 647 bool "Intel Low Power Subsystem Support" 648 depends on X86 && ACPI && PCI 649 select COMMON_CLK 650 select PINCTRL 651 select IOSF_MBI 652 help 653 Select to build support for Intel Low Power Subsystem such as 654 found on Intel Lynxpoint PCH. Selecting this option enables 655 things like clock tree (common clock framework) and pincontrol 656 which are needed by the LPSS peripheral drivers. 657 658config X86_AMD_PLATFORM_DEVICE 659 bool "AMD ACPI2Platform devices support" 660 depends on ACPI 661 select COMMON_CLK 662 select PINCTRL 663 help 664 Select to interpret AMD specific ACPI device to platform device 665 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 666 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 667 implemented under PINCTRL subsystem. 668 669config IOSF_MBI 670 tristate "Intel SoC IOSF Sideband support for SoC platforms" 671 depends on PCI 672 help 673 This option enables sideband register access support for Intel SoC 674 platforms. On these platforms the IOSF sideband is used in lieu of 675 MSR's for some register accesses, mostly but not limited to thermal 676 and power. Drivers may query the availability of this device to 677 determine if they need the sideband in order to work on these 678 platforms. The sideband is available on the following SoC products. 679 This list is not meant to be exclusive. 680 - BayTrail 681 - Braswell 682 - Quark 683 684 You should say Y if you are running a kernel on one of these SoC's. 685 686config IOSF_MBI_DEBUG 687 bool "Enable IOSF sideband access through debugfs" 688 depends on IOSF_MBI && DEBUG_FS 689 help 690 Select this option to expose the IOSF sideband access registers (MCR, 691 MDR, MCRX) through debugfs to write and read register information from 692 different units on the SoC. This is most useful for obtaining device 693 state information for debug and analysis. As this is a general access 694 mechanism, users of this option would have specific knowledge of the 695 device they want to access. 696 697 If you don't require the option or are in doubt, say N. 698 699config X86_RDC321X 700 bool "RDC R-321x SoC" 701 depends on X86_32 702 depends on X86_EXTENDED_PLATFORM 703 select M486 704 select X86_REBOOTFIXUPS 705 help 706 This option is needed for RDC R-321x system-on-chip, also known 707 as R-8610-(G). 708 If you don't have one of these chips, you should say N here. 709 710config X86_32_NON_STANDARD 711 bool "Support non-standard 32-bit SMP architectures" 712 depends on X86_32 && SMP 713 depends on X86_EXTENDED_PLATFORM 714 help 715 This option compiles in the bigsmp and STA2X11 default 716 subarchitectures. It is intended for a generic binary 717 kernel. If you select them all, kernel will probe it one by 718 one and will fallback to default. 719 720# Alphabetically sorted list of Non standard 32 bit platforms 721 722config X86_SUPPORTS_MEMORY_FAILURE 723 def_bool y 724 # MCE code calls memory_failure(): 725 depends on X86_MCE 726 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 727 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 728 depends on X86_64 || !SPARSEMEM 729 select ARCH_SUPPORTS_MEMORY_FAILURE 730 731config STA2X11 732 bool "STA2X11 Companion Chip Support" 733 depends on X86_32_NON_STANDARD && PCI 734 select SWIOTLB 735 select MFD_STA2X11 736 select GPIOLIB 737 help 738 This adds support for boards based on the STA2X11 IO-Hub, 739 a.k.a. "ConneXt". The chip is used in place of the standard 740 PC chipset, so all "standard" peripherals are missing. If this 741 option is selected the kernel will still be able to boot on 742 standard PC machines. 743 744config X86_32_IRIS 745 tristate "Eurobraille/Iris poweroff module" 746 depends on X86_32 747 help 748 The Iris machines from EuroBraille do not have APM or ACPI support 749 to shut themselves down properly. A special I/O sequence is 750 needed to do so, which is what this module does at 751 kernel shutdown. 752 753 This is only for Iris machines from EuroBraille. 754 755 If unused, say N. 756 757config SCHED_OMIT_FRAME_POINTER 758 def_bool y 759 prompt "Single-depth WCHAN output" 760 depends on X86 761 help 762 Calculate simpler /proc/<PID>/wchan values. If this option 763 is disabled then wchan values will recurse back to the 764 caller function. This provides more accurate wchan values, 765 at the expense of slightly more scheduling overhead. 766 767 If in doubt, say "Y". 768 769menuconfig HYPERVISOR_GUEST 770 bool "Linux guest support" 771 help 772 Say Y here to enable options for running Linux under various hyper- 773 visors. This option enables basic hypervisor detection and platform 774 setup. 775 776 If you say N, all options in this submenu will be skipped and 777 disabled, and Linux guest support won't be built in. 778 779if HYPERVISOR_GUEST 780 781config PARAVIRT 782 bool "Enable paravirtualization code" 783 depends on HAVE_STATIC_CALL 784 help 785 This changes the kernel so it can modify itself when it is run 786 under a hypervisor, potentially improving performance significantly 787 over full virtualization. However, when run without a hypervisor 788 the kernel is theoretically slower and slightly larger. 789 790config PARAVIRT_XXL 791 bool 792 793config PARAVIRT_DEBUG 794 bool "paravirt-ops debugging" 795 depends on PARAVIRT && DEBUG_KERNEL 796 help 797 Enable to debug paravirt_ops internals. Specifically, BUG if 798 a paravirt_op is missing when it is called. 799 800config PARAVIRT_SPINLOCKS 801 bool "Paravirtualization layer for spinlocks" 802 depends on PARAVIRT && SMP 803 help 804 Paravirtualized spinlocks allow a pvops backend to replace the 805 spinlock implementation with something virtualization-friendly 806 (for example, block the virtual CPU rather than spinning). 807 808 It has a minimal impact on native kernels and gives a nice performance 809 benefit on paravirtualized KVM / Xen kernels. 810 811 If you are unsure how to answer this question, answer Y. 812 813config X86_HV_CALLBACK_VECTOR 814 def_bool n 815 816source "arch/x86/xen/Kconfig" 817 818config KVM_GUEST 819 bool "KVM Guest support (including kvmclock)" 820 depends on PARAVIRT 821 select PARAVIRT_CLOCK 822 select ARCH_CPUIDLE_HALTPOLL 823 select X86_HV_CALLBACK_VECTOR 824 default y 825 help 826 This option enables various optimizations for running under the KVM 827 hypervisor. It includes a paravirtualized clock, so that instead 828 of relying on a PIT (or probably other) emulation by the 829 underlying device model, the host provides the guest with 830 timing infrastructure such as time of day, and system time 831 832config ARCH_CPUIDLE_HALTPOLL 833 def_bool n 834 prompt "Disable host haltpoll when loading haltpoll driver" 835 help 836 If virtualized under KVM, disable host haltpoll. 837 838config PVH 839 bool "Support for running PVH guests" 840 help 841 This option enables the PVH entry point for guest virtual machines 842 as specified in the x86/HVM direct boot ABI. 843 844config PARAVIRT_TIME_ACCOUNTING 845 bool "Paravirtual steal time accounting" 846 depends on PARAVIRT 847 help 848 Select this option to enable fine granularity task steal time 849 accounting. Time spent executing other tasks in parallel with 850 the current vCPU is discounted from the vCPU power. To account for 851 that, there can be a small performance impact. 852 853 If in doubt, say N here. 854 855config PARAVIRT_CLOCK 856 bool 857 858config JAILHOUSE_GUEST 859 bool "Jailhouse non-root cell support" 860 depends on X86_64 && PCI 861 select X86_PM_TIMER 862 help 863 This option allows to run Linux as guest in a Jailhouse non-root 864 cell. You can leave this option disabled if you only want to start 865 Jailhouse and run Linux afterwards in the root cell. 866 867config ACRN_GUEST 868 bool "ACRN Guest support" 869 depends on X86_64 870 select X86_HV_CALLBACK_VECTOR 871 help 872 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 873 a flexible, lightweight reference open-source hypervisor, built with 874 real-time and safety-criticality in mind. It is built for embedded 875 IOT with small footprint and real-time features. More details can be 876 found in https://projectacrn.org/. 877 878config INTEL_TDX_GUEST 879 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 880 depends on X86_64 && CPU_SUP_INTEL 881 depends on X86_X2APIC 882 depends on EFI_STUB 883 select ARCH_HAS_CC_PLATFORM 884 select X86_MEM_ENCRYPT 885 select X86_MCE 886 select UNACCEPTED_MEMORY 887 help 888 Support running as a guest under Intel TDX. Without this support, 889 the guest kernel can not boot or run under TDX. 890 TDX includes memory encryption and integrity capabilities 891 which protect the confidentiality and integrity of guest 892 memory contents and CPU state. TDX guests are protected from 893 some attacks from the VMM. 894 895endif # HYPERVISOR_GUEST 896 897source "arch/x86/Kconfig.cpu" 898 899config HPET_TIMER 900 def_bool X86_64 901 prompt "HPET Timer Support" if X86_32 902 help 903 Use the IA-PC HPET (High Precision Event Timer) to manage 904 time in preference to the PIT and RTC, if a HPET is 905 present. 906 HPET is the next generation timer replacing legacy 8254s. 907 The HPET provides a stable time base on SMP 908 systems, unlike the TSC, but it is more expensive to access, 909 as it is off-chip. The interface used is documented 910 in the HPET spec, revision 1. 911 912 You can safely choose Y here. However, HPET will only be 913 activated if the platform and the BIOS support this feature. 914 Otherwise the 8254 will be used for timing services. 915 916 Choose N to continue using the legacy 8254 timer. 917 918config HPET_EMULATE_RTC 919 def_bool y 920 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 921 922# Mark as expert because too many people got it wrong. 923# The code disables itself when not needed. 924config DMI 925 default y 926 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 927 bool "Enable DMI scanning" if EXPERT 928 help 929 Enabled scanning of DMI to identify machine quirks. Say Y 930 here unless you have verified that your setup is not 931 affected by entries in the DMI blacklist. Required by PNP 932 BIOS code. 933 934config GART_IOMMU 935 bool "Old AMD GART IOMMU support" 936 select DMA_OPS 937 select IOMMU_HELPER 938 select SWIOTLB 939 depends on X86_64 && PCI && AMD_NB 940 help 941 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 942 GART based hardware IOMMUs. 943 944 The GART supports full DMA access for devices with 32-bit access 945 limitations, on systems with more than 3 GB. This is usually needed 946 for USB, sound, many IDE/SATA chipsets and some other devices. 947 948 Newer systems typically have a modern AMD IOMMU, supported via 949 the CONFIG_AMD_IOMMU=y config option. 950 951 In normal configurations this driver is only active when needed: 952 there's more than 3 GB of memory and the system contains a 953 32-bit limited device. 954 955 If unsure, say Y. 956 957config BOOT_VESA_SUPPORT 958 bool 959 help 960 If true, at least one selected framebuffer driver can take advantage 961 of VESA video modes set at an early boot stage via the vga= parameter. 962 963config MAXSMP 964 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 965 depends on X86_64 && SMP && DEBUG_KERNEL 966 select CPUMASK_OFFSTACK 967 help 968 Enable maximum number of CPUS and NUMA Nodes for this architecture. 969 If unsure, say N. 970 971# 972# The maximum number of CPUs supported: 973# 974# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 975# and which can be configured interactively in the 976# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 977# 978# The ranges are different on 32-bit and 64-bit kernels, depending on 979# hardware capabilities and scalability features of the kernel. 980# 981# ( If MAXSMP is enabled we just use the highest possible value and disable 982# interactive configuration. ) 983# 984 985config NR_CPUS_RANGE_BEGIN 986 int 987 default NR_CPUS_RANGE_END if MAXSMP 988 default 1 if !SMP 989 default 2 990 991config NR_CPUS_RANGE_END 992 int 993 depends on X86_32 994 default 64 if SMP && X86_BIGSMP 995 default 8 if SMP && !X86_BIGSMP 996 default 1 if !SMP 997 998config NR_CPUS_RANGE_END 999 int 1000 depends on X86_64 1001 default 8192 if SMP && CPUMASK_OFFSTACK 1002 default 512 if SMP && !CPUMASK_OFFSTACK 1003 default 1 if !SMP 1004 1005config NR_CPUS_DEFAULT 1006 int 1007 depends on X86_32 1008 default 32 if X86_BIGSMP 1009 default 8 if SMP 1010 default 1 if !SMP 1011 1012config NR_CPUS_DEFAULT 1013 int 1014 depends on X86_64 1015 default 8192 if MAXSMP 1016 default 64 if SMP 1017 default 1 if !SMP 1018 1019config NR_CPUS 1020 int "Maximum number of CPUs" if SMP && !MAXSMP 1021 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1022 default NR_CPUS_DEFAULT 1023 help 1024 This allows you to specify the maximum number of CPUs which this 1025 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1026 supported value is 8192, otherwise the maximum value is 512. The 1027 minimum value which makes sense is 2. 1028 1029 This is purely to save memory: each supported CPU adds about 8KB 1030 to the kernel image. 1031 1032config SCHED_CLUSTER 1033 bool "Cluster scheduler support" 1034 depends on SMP 1035 default y 1036 help 1037 Cluster scheduler support improves the CPU scheduler's decision 1038 making when dealing with machines that have clusters of CPUs. 1039 Cluster usually means a couple of CPUs which are placed closely 1040 by sharing mid-level caches, last-level cache tags or internal 1041 busses. 1042 1043config SCHED_SMT 1044 def_bool y if SMP 1045 1046config SCHED_MC 1047 def_bool y 1048 prompt "Multi-core scheduler support" 1049 depends on SMP 1050 help 1051 Multi-core scheduler support improves the CPU scheduler's decision 1052 making when dealing with multi-core CPU chips at a cost of slightly 1053 increased overhead in some places. If unsure say N here. 1054 1055config SCHED_MC_PRIO 1056 bool "CPU core priorities scheduler support" 1057 depends on SCHED_MC && CPU_SUP_INTEL 1058 select X86_INTEL_PSTATE 1059 select CPU_FREQ 1060 default y 1061 help 1062 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1063 core ordering determined at manufacturing time, which allows 1064 certain cores to reach higher turbo frequencies (when running 1065 single threaded workloads) than others. 1066 1067 Enabling this kernel feature teaches the scheduler about 1068 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1069 scheduler's CPU selection logic accordingly, so that higher 1070 overall system performance can be achieved. 1071 1072 This feature will have no effect on CPUs without this feature. 1073 1074 If unsure say Y here. 1075 1076config UP_LATE_INIT 1077 def_bool y 1078 depends on !SMP && X86_LOCAL_APIC 1079 1080config X86_UP_APIC 1081 bool "Local APIC support on uniprocessors" if !PCI_MSI 1082 default PCI_MSI 1083 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1084 help 1085 A local APIC (Advanced Programmable Interrupt Controller) is an 1086 integrated interrupt controller in the CPU. If you have a single-CPU 1087 system which has a processor with a local APIC, you can say Y here to 1088 enable and use it. If you say Y here even though your machine doesn't 1089 have a local APIC, then the kernel will still run with no slowdown at 1090 all. The local APIC supports CPU-generated self-interrupts (timer, 1091 performance counters), and the NMI watchdog which detects hard 1092 lockups. 1093 1094config X86_UP_IOAPIC 1095 bool "IO-APIC support on uniprocessors" 1096 depends on X86_UP_APIC 1097 help 1098 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1099 SMP-capable replacement for PC-style interrupt controllers. Most 1100 SMP systems and many recent uniprocessor systems have one. 1101 1102 If you have a single-CPU system with an IO-APIC, you can say Y here 1103 to use it. If you say Y here even though your machine doesn't have 1104 an IO-APIC, then the kernel will still run with no slowdown at all. 1105 1106config X86_LOCAL_APIC 1107 def_bool y 1108 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1109 select IRQ_DOMAIN_HIERARCHY 1110 1111config X86_IO_APIC 1112 def_bool y 1113 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1114 1115config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1116 bool "Reroute for broken boot IRQs" 1117 depends on X86_IO_APIC 1118 help 1119 This option enables a workaround that fixes a source of 1120 spurious interrupts. This is recommended when threaded 1121 interrupt handling is used on systems where the generation of 1122 superfluous "boot interrupts" cannot be disabled. 1123 1124 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1125 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1126 kernel does during interrupt handling). On chipsets where this 1127 boot IRQ generation cannot be disabled, this workaround keeps 1128 the original IRQ line masked so that only the equivalent "boot 1129 IRQ" is delivered to the CPUs. The workaround also tells the 1130 kernel to set up the IRQ handler on the boot IRQ line. In this 1131 way only one interrupt is delivered to the kernel. Otherwise 1132 the spurious second interrupt may cause the kernel to bring 1133 down (vital) interrupt lines. 1134 1135 Only affects "broken" chipsets. Interrupt sharing may be 1136 increased on these systems. 1137 1138config X86_MCE 1139 bool "Machine Check / overheating reporting" 1140 select GENERIC_ALLOCATOR 1141 default y 1142 help 1143 Machine Check support allows the processor to notify the 1144 kernel if it detects a problem (e.g. overheating, data corruption). 1145 The action the kernel takes depends on the severity of the problem, 1146 ranging from warning messages to halting the machine. 1147 1148config X86_MCELOG_LEGACY 1149 bool "Support for deprecated /dev/mcelog character device" 1150 depends on X86_MCE 1151 help 1152 Enable support for /dev/mcelog which is needed by the old mcelog 1153 userspace logging daemon. Consider switching to the new generation 1154 rasdaemon solution. 1155 1156config X86_MCE_INTEL 1157 def_bool y 1158 prompt "Intel MCE features" 1159 depends on X86_MCE && X86_LOCAL_APIC 1160 help 1161 Additional support for intel specific MCE features such as 1162 the thermal monitor. 1163 1164config X86_MCE_AMD 1165 def_bool y 1166 prompt "AMD MCE features" 1167 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1168 help 1169 Additional support for AMD specific MCE features such as 1170 the DRAM Error Threshold. 1171 1172config X86_ANCIENT_MCE 1173 bool "Support for old Pentium 5 / WinChip machine checks" 1174 depends on X86_32 && X86_MCE 1175 help 1176 Include support for machine check handling on old Pentium 5 or WinChip 1177 systems. These typically need to be enabled explicitly on the command 1178 line. 1179 1180config X86_MCE_THRESHOLD 1181 depends on X86_MCE_AMD || X86_MCE_INTEL 1182 def_bool y 1183 1184config X86_MCE_INJECT 1185 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1186 tristate "Machine check injector support" 1187 help 1188 Provide support for injecting machine checks for testing purposes. 1189 If you don't know what a machine check is and you don't do kernel 1190 QA it is safe to say n. 1191 1192source "arch/x86/events/Kconfig" 1193 1194config X86_LEGACY_VM86 1195 bool "Legacy VM86 support" 1196 depends on X86_32 1197 help 1198 This option allows user programs to put the CPU into V8086 1199 mode, which is an 80286-era approximation of 16-bit real mode. 1200 1201 Some very old versions of X and/or vbetool require this option 1202 for user mode setting. Similarly, DOSEMU will use it if 1203 available to accelerate real mode DOS programs. However, any 1204 recent version of DOSEMU, X, or vbetool should be fully 1205 functional even without kernel VM86 support, as they will all 1206 fall back to software emulation. Nevertheless, if you are using 1207 a 16-bit DOS program where 16-bit performance matters, vm86 1208 mode might be faster than emulation and you might want to 1209 enable this option. 1210 1211 Note that any app that works on a 64-bit kernel is unlikely to 1212 need this option, as 64-bit kernels don't, and can't, support 1213 V8086 mode. This option is also unrelated to 16-bit protected 1214 mode and is not needed to run most 16-bit programs under Wine. 1215 1216 Enabling this option increases the complexity of the kernel 1217 and slows down exception handling a tiny bit. 1218 1219 If unsure, say N here. 1220 1221config VM86 1222 bool 1223 default X86_LEGACY_VM86 1224 1225config X86_16BIT 1226 bool "Enable support for 16-bit segments" if EXPERT 1227 default y 1228 depends on MODIFY_LDT_SYSCALL 1229 help 1230 This option is required by programs like Wine to run 16-bit 1231 protected mode legacy code on x86 processors. Disabling 1232 this option saves about 300 bytes on i386, or around 6K text 1233 plus 16K runtime memory on x86-64, 1234 1235config X86_ESPFIX32 1236 def_bool y 1237 depends on X86_16BIT && X86_32 1238 1239config X86_ESPFIX64 1240 def_bool y 1241 depends on X86_16BIT && X86_64 1242 1243config X86_VSYSCALL_EMULATION 1244 bool "Enable vsyscall emulation" if EXPERT 1245 default y 1246 depends on X86_64 1247 help 1248 This enables emulation of the legacy vsyscall page. Disabling 1249 it is roughly equivalent to booting with vsyscall=none, except 1250 that it will also disable the helpful warning if a program 1251 tries to use a vsyscall. With this option set to N, offending 1252 programs will just segfault, citing addresses of the form 1253 0xffffffffff600?00. 1254 1255 This option is required by many programs built before 2013, and 1256 care should be used even with newer programs if set to N. 1257 1258 Disabling this option saves about 7K of kernel size and 1259 possibly 4K of additional runtime pagetable memory. 1260 1261config X86_IOPL_IOPERM 1262 bool "IOPERM and IOPL Emulation" 1263 default y 1264 help 1265 This enables the ioperm() and iopl() syscalls which are necessary 1266 for legacy applications. 1267 1268 Legacy IOPL support is an overbroad mechanism which allows user 1269 space aside of accessing all 65536 I/O ports also to disable 1270 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1271 capabilities and permission from potentially active security 1272 modules. 1273 1274 The emulation restricts the functionality of the syscall to 1275 only allowing the full range I/O port access, but prevents the 1276 ability to disable interrupts from user space which would be 1277 granted if the hardware IOPL mechanism would be used. 1278 1279config TOSHIBA 1280 tristate "Toshiba Laptop support" 1281 depends on X86_32 1282 help 1283 This adds a driver to safely access the System Management Mode of 1284 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1285 not work on models with a Phoenix BIOS. The System Management Mode 1286 is used to set the BIOS and power saving options on Toshiba portables. 1287 1288 For information on utilities to make use of this driver see the 1289 Toshiba Linux utilities web site at: 1290 <http://www.buzzard.org.uk/toshiba/>. 1291 1292 Say Y if you intend to run this kernel on a Toshiba portable. 1293 Say N otherwise. 1294 1295config X86_REBOOTFIXUPS 1296 bool "Enable X86 board specific fixups for reboot" 1297 depends on X86_32 1298 help 1299 This enables chipset and/or board specific fixups to be done 1300 in order to get reboot to work correctly. This is only needed on 1301 some combinations of hardware and BIOS. The symptom, for which 1302 this config is intended, is when reboot ends with a stalled/hung 1303 system. 1304 1305 Currently, the only fixup is for the Geode machines using 1306 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1307 1308 Say Y if you want to enable the fixup. Currently, it's safe to 1309 enable this option even if you don't need it. 1310 Say N otherwise. 1311 1312config MICROCODE 1313 def_bool y 1314 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1315 1316config MICROCODE_LATE_LOADING 1317 bool "Late microcode loading (DANGEROUS)" 1318 default n 1319 depends on MICROCODE 1320 help 1321 Loading microcode late, when the system is up and executing instructions 1322 is a tricky business and should be avoided if possible. Just the sequence 1323 of synchronizing all cores and SMT threads is one fragile dance which does 1324 not guarantee that cores might not softlock after the loading. Therefore, 1325 use this at your own risk. Late loading taints the kernel too. 1326 1327config X86_MSR 1328 tristate "/dev/cpu/*/msr - Model-specific register support" 1329 help 1330 This device gives privileged processes access to the x86 1331 Model-Specific Registers (MSRs). It is a character device with 1332 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1333 MSR accesses are directed to a specific CPU on multi-processor 1334 systems. 1335 1336config X86_CPUID 1337 tristate "/dev/cpu/*/cpuid - CPU information support" 1338 help 1339 This device gives processes access to the x86 CPUID instruction to 1340 be executed on a specific processor. It is a character device 1341 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1342 /dev/cpu/31/cpuid. 1343 1344choice 1345 prompt "High Memory Support" 1346 default HIGHMEM4G 1347 depends on X86_32 1348 1349config NOHIGHMEM 1350 bool "off" 1351 help 1352 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1353 However, the address space of 32-bit x86 processors is only 4 1354 Gigabytes large. That means that, if you have a large amount of 1355 physical memory, not all of it can be "permanently mapped" by the 1356 kernel. The physical memory that's not permanently mapped is called 1357 "high memory". 1358 1359 If you are compiling a kernel which will never run on a machine with 1360 more than 1 Gigabyte total physical RAM, answer "off" here (default 1361 choice and suitable for most users). This will result in a "3GB/1GB" 1362 split: 3GB are mapped so that each process sees a 3GB virtual memory 1363 space and the remaining part of the 4GB virtual memory space is used 1364 by the kernel to permanently map as much physical memory as 1365 possible. 1366 1367 If the machine has between 1 and 4 Gigabytes physical RAM, then 1368 answer "4GB" here. 1369 1370 If more than 4 Gigabytes is used then answer "64GB" here. This 1371 selection turns Intel PAE (Physical Address Extension) mode on. 1372 PAE implements 3-level paging on IA32 processors. PAE is fully 1373 supported by Linux, PAE mode is implemented on all recent Intel 1374 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1375 then the kernel will not boot on CPUs that don't support PAE! 1376 1377 The actual amount of total physical memory will either be 1378 auto detected or can be forced by using a kernel command line option 1379 such as "mem=256M". (Try "man bootparam" or see the documentation of 1380 your boot loader (lilo or loadlin) about how to pass options to the 1381 kernel at boot time.) 1382 1383 If unsure, say "off". 1384 1385config HIGHMEM4G 1386 bool "4GB" 1387 help 1388 Select this if you have a 32-bit processor and between 1 and 4 1389 gigabytes of physical RAM. 1390 1391config HIGHMEM64G 1392 bool "64GB" 1393 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1394 select X86_PAE 1395 help 1396 Select this if you have a 32-bit processor and more than 4 1397 gigabytes of physical RAM. 1398 1399endchoice 1400 1401choice 1402 prompt "Memory split" if EXPERT 1403 default VMSPLIT_3G 1404 depends on X86_32 1405 help 1406 Select the desired split between kernel and user memory. 1407 1408 If the address range available to the kernel is less than the 1409 physical memory installed, the remaining memory will be available 1410 as "high memory". Accessing high memory is a little more costly 1411 than low memory, as it needs to be mapped into the kernel first. 1412 Note that increasing the kernel address space limits the range 1413 available to user programs, making the address space there 1414 tighter. Selecting anything other than the default 3G/1G split 1415 will also likely make your kernel incompatible with binary-only 1416 kernel modules. 1417 1418 If you are not absolutely sure what you are doing, leave this 1419 option alone! 1420 1421 config VMSPLIT_3G 1422 bool "3G/1G user/kernel split" 1423 config VMSPLIT_3G_OPT 1424 depends on !X86_PAE 1425 bool "3G/1G user/kernel split (for full 1G low memory)" 1426 config VMSPLIT_2G 1427 bool "2G/2G user/kernel split" 1428 config VMSPLIT_2G_OPT 1429 depends on !X86_PAE 1430 bool "2G/2G user/kernel split (for full 2G low memory)" 1431 config VMSPLIT_1G 1432 bool "1G/3G user/kernel split" 1433endchoice 1434 1435config PAGE_OFFSET 1436 hex 1437 default 0xB0000000 if VMSPLIT_3G_OPT 1438 default 0x80000000 if VMSPLIT_2G 1439 default 0x78000000 if VMSPLIT_2G_OPT 1440 default 0x40000000 if VMSPLIT_1G 1441 default 0xC0000000 1442 depends on X86_32 1443 1444config HIGHMEM 1445 def_bool y 1446 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1447 1448config X86_PAE 1449 bool "PAE (Physical Address Extension) Support" 1450 depends on X86_32 && !HIGHMEM4G 1451 select PHYS_ADDR_T_64BIT 1452 select SWIOTLB 1453 help 1454 PAE is required for NX support, and furthermore enables 1455 larger swapspace support for non-overcommit purposes. It 1456 has the cost of more pagetable lookup overhead, and also 1457 consumes more pagetable space per process. 1458 1459config X86_5LEVEL 1460 bool "Enable 5-level page tables support" 1461 default y 1462 select DYNAMIC_MEMORY_LAYOUT 1463 select SPARSEMEM_VMEMMAP 1464 depends on X86_64 1465 help 1466 5-level paging enables access to larger address space: 1467 up to 128 PiB of virtual address space and 4 PiB of 1468 physical address space. 1469 1470 It will be supported by future Intel CPUs. 1471 1472 A kernel with the option enabled can be booted on machines that 1473 support 4- or 5-level paging. 1474 1475 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1476 information. 1477 1478 Say N if unsure. 1479 1480config X86_DIRECT_GBPAGES 1481 def_bool y 1482 depends on X86_64 1483 help 1484 Certain kernel features effectively disable kernel 1485 linear 1 GB mappings (even if the CPU otherwise 1486 supports them), so don't confuse the user by printing 1487 that we have them enabled. 1488 1489config X86_CPA_STATISTICS 1490 bool "Enable statistic for Change Page Attribute" 1491 depends on DEBUG_FS 1492 help 1493 Expose statistics about the Change Page Attribute mechanism, which 1494 helps to determine the effectiveness of preserving large and huge 1495 page mappings when mapping protections are changed. 1496 1497config X86_MEM_ENCRYPT 1498 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1499 select DYNAMIC_PHYSICAL_MASK 1500 def_bool n 1501 1502config AMD_MEM_ENCRYPT 1503 bool "AMD Secure Memory Encryption (SME) support" 1504 depends on X86_64 && CPU_SUP_AMD 1505 depends on EFI_STUB 1506 select DMA_COHERENT_POOL 1507 select ARCH_USE_MEMREMAP_PROT 1508 select INSTRUCTION_DECODER 1509 select ARCH_HAS_CC_PLATFORM 1510 select X86_MEM_ENCRYPT 1511 select UNACCEPTED_MEMORY 1512 help 1513 Say yes to enable support for the encryption of system memory. 1514 This requires an AMD processor that supports Secure Memory 1515 Encryption (SME). 1516 1517config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1518 bool "Activate AMD Secure Memory Encryption (SME) by default" 1519 depends on AMD_MEM_ENCRYPT 1520 help 1521 Say yes to have system memory encrypted by default if running on 1522 an AMD processor that supports Secure Memory Encryption (SME). 1523 1524 If set to Y, then the encryption of system memory can be 1525 deactivated with the mem_encrypt=off command line option. 1526 1527 If set to N, then the encryption of system memory can be 1528 activated with the mem_encrypt=on command line option. 1529 1530# Common NUMA Features 1531config NUMA 1532 bool "NUMA Memory Allocation and Scheduler Support" 1533 depends on SMP 1534 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1535 default y if X86_BIGSMP 1536 select USE_PERCPU_NUMA_NODE_ID 1537 help 1538 Enable NUMA (Non-Uniform Memory Access) support. 1539 1540 The kernel will try to allocate memory used by a CPU on the 1541 local memory controller of the CPU and add some more 1542 NUMA awareness to the kernel. 1543 1544 For 64-bit this is recommended if the system is Intel Core i7 1545 (or later), AMD Opteron, or EM64T NUMA. 1546 1547 For 32-bit this is only needed if you boot a 32-bit 1548 kernel on a 64-bit NUMA platform. 1549 1550 Otherwise, you should say N. 1551 1552config AMD_NUMA 1553 def_bool y 1554 prompt "Old style AMD Opteron NUMA detection" 1555 depends on X86_64 && NUMA && PCI 1556 help 1557 Enable AMD NUMA node topology detection. You should say Y here if 1558 you have a multi processor AMD system. This uses an old method to 1559 read the NUMA configuration directly from the builtin Northbridge 1560 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1561 which also takes priority if both are compiled in. 1562 1563config X86_64_ACPI_NUMA 1564 def_bool y 1565 prompt "ACPI NUMA detection" 1566 depends on X86_64 && NUMA && ACPI && PCI 1567 select ACPI_NUMA 1568 help 1569 Enable ACPI SRAT based node topology detection. 1570 1571config NUMA_EMU 1572 bool "NUMA emulation" 1573 depends on NUMA 1574 help 1575 Enable NUMA emulation. A flat machine will be split 1576 into virtual nodes when booted with "numa=fake=N", where N is the 1577 number of nodes. This is only useful for debugging. 1578 1579config NODES_SHIFT 1580 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1581 range 1 10 1582 default "10" if MAXSMP 1583 default "6" if X86_64 1584 default "3" 1585 depends on NUMA 1586 help 1587 Specify the maximum number of NUMA Nodes available on the target 1588 system. Increases memory reserved to accommodate various tables. 1589 1590config ARCH_FLATMEM_ENABLE 1591 def_bool y 1592 depends on X86_32 && !NUMA 1593 1594config ARCH_SPARSEMEM_ENABLE 1595 def_bool y 1596 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1597 select SPARSEMEM_STATIC if X86_32 1598 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1599 1600config ARCH_SPARSEMEM_DEFAULT 1601 def_bool X86_64 || (NUMA && X86_32) 1602 1603config ARCH_SELECT_MEMORY_MODEL 1604 def_bool y 1605 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1606 1607config ARCH_MEMORY_PROBE 1608 bool "Enable sysfs memory/probe interface" 1609 depends on MEMORY_HOTPLUG 1610 help 1611 This option enables a sysfs memory/probe interface for testing. 1612 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1613 If you are unsure how to answer this question, answer N. 1614 1615config ARCH_PROC_KCORE_TEXT 1616 def_bool y 1617 depends on X86_64 && PROC_KCORE 1618 1619config ILLEGAL_POINTER_VALUE 1620 hex 1621 default 0 if X86_32 1622 default 0xdead000000000000 if X86_64 1623 1624config X86_PMEM_LEGACY_DEVICE 1625 bool 1626 1627config X86_PMEM_LEGACY 1628 tristate "Support non-standard NVDIMMs and ADR protected memory" 1629 depends on PHYS_ADDR_T_64BIT 1630 depends on BLK_DEV 1631 select X86_PMEM_LEGACY_DEVICE 1632 select NUMA_KEEP_MEMINFO if NUMA 1633 select LIBNVDIMM 1634 help 1635 Treat memory marked using the non-standard e820 type of 12 as used 1636 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1637 The kernel will offer these regions to the 'pmem' driver so 1638 they can be used for persistent storage. 1639 1640 Say Y if unsure. 1641 1642config HIGHPTE 1643 bool "Allocate 3rd-level pagetables from highmem" 1644 depends on HIGHMEM 1645 help 1646 The VM uses one page table entry for each page of physical memory. 1647 For systems with a lot of RAM, this can be wasteful of precious 1648 low memory. Setting this option will put user-space page table 1649 entries in high memory. 1650 1651config X86_CHECK_BIOS_CORRUPTION 1652 bool "Check for low memory corruption" 1653 help 1654 Periodically check for memory corruption in low memory, which 1655 is suspected to be caused by BIOS. Even when enabled in the 1656 configuration, it is disabled at runtime. Enable it by 1657 setting "memory_corruption_check=1" on the kernel command 1658 line. By default it scans the low 64k of memory every 60 1659 seconds; see the memory_corruption_check_size and 1660 memory_corruption_check_period parameters in 1661 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1662 1663 When enabled with the default parameters, this option has 1664 almost no overhead, as it reserves a relatively small amount 1665 of memory and scans it infrequently. It both detects corruption 1666 and prevents it from affecting the running system. 1667 1668 It is, however, intended as a diagnostic tool; if repeatable 1669 BIOS-originated corruption always affects the same memory, 1670 you can use memmap= to prevent the kernel from using that 1671 memory. 1672 1673config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1674 bool "Set the default setting of memory_corruption_check" 1675 depends on X86_CHECK_BIOS_CORRUPTION 1676 default y 1677 help 1678 Set whether the default state of memory_corruption_check is 1679 on or off. 1680 1681config MATH_EMULATION 1682 bool 1683 depends on MODIFY_LDT_SYSCALL 1684 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1685 help 1686 Linux can emulate a math coprocessor (used for floating point 1687 operations) if you don't have one. 486DX and Pentium processors have 1688 a math coprocessor built in, 486SX and 386 do not, unless you added 1689 a 487DX or 387, respectively. (The messages during boot time can 1690 give you some hints here ["man dmesg"].) Everyone needs either a 1691 coprocessor or this emulation. 1692 1693 If you don't have a math coprocessor, you need to say Y here; if you 1694 say Y here even though you have a coprocessor, the coprocessor will 1695 be used nevertheless. (This behavior can be changed with the kernel 1696 command line option "no387", which comes handy if your coprocessor 1697 is broken. Try "man bootparam" or see the documentation of your boot 1698 loader (lilo or loadlin) about how to pass options to the kernel at 1699 boot time.) This means that it is a good idea to say Y here if you 1700 intend to use this kernel on different machines. 1701 1702 More information about the internals of the Linux math coprocessor 1703 emulation can be found in <file:arch/x86/math-emu/README>. 1704 1705 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1706 kernel, it won't hurt. 1707 1708config MTRR 1709 def_bool y 1710 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1711 help 1712 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1713 the Memory Type Range Registers (MTRRs) may be used to control 1714 processor access to memory ranges. This is most useful if you have 1715 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1716 allows bus write transfers to be combined into a larger transfer 1717 before bursting over the PCI/AGP bus. This can increase performance 1718 of image write operations 2.5 times or more. Saying Y here creates a 1719 /proc/mtrr file which may be used to manipulate your processor's 1720 MTRRs. Typically the X server should use this. 1721 1722 This code has a reasonably generic interface so that similar 1723 control registers on other processors can be easily supported 1724 as well: 1725 1726 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1727 Registers (ARRs) which provide a similar functionality to MTRRs. For 1728 these, the ARRs are used to emulate the MTRRs. 1729 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1730 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1731 write-combining. All of these processors are supported by this code 1732 and it makes sense to say Y here if you have one of them. 1733 1734 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1735 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1736 can lead to all sorts of problems, so it's good to say Y here. 1737 1738 You can safely say Y even if your machine doesn't have MTRRs, you'll 1739 just add about 9 KB to your kernel. 1740 1741 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1742 1743config MTRR_SANITIZER 1744 def_bool y 1745 prompt "MTRR cleanup support" 1746 depends on MTRR 1747 help 1748 Convert MTRR layout from continuous to discrete, so X drivers can 1749 add writeback entries. 1750 1751 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1752 The largest mtrr entry size for a continuous block can be set with 1753 mtrr_chunk_size. 1754 1755 If unsure, say Y. 1756 1757config MTRR_SANITIZER_ENABLE_DEFAULT 1758 int "MTRR cleanup enable value (0-1)" 1759 range 0 1 1760 default "0" 1761 depends on MTRR_SANITIZER 1762 help 1763 Enable mtrr cleanup default value 1764 1765config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1766 int "MTRR cleanup spare reg num (0-7)" 1767 range 0 7 1768 default "1" 1769 depends on MTRR_SANITIZER 1770 help 1771 mtrr cleanup spare entries default, it can be changed via 1772 mtrr_spare_reg_nr=N on the kernel command line. 1773 1774config X86_PAT 1775 def_bool y 1776 prompt "x86 PAT support" if EXPERT 1777 depends on MTRR 1778 help 1779 Use PAT attributes to setup page level cache control. 1780 1781 PATs are the modern equivalents of MTRRs and are much more 1782 flexible than MTRRs. 1783 1784 Say N here if you see bootup problems (boot crash, boot hang, 1785 spontaneous reboots) or a non-working video driver. 1786 1787 If unsure, say Y. 1788 1789config ARCH_USES_PG_UNCACHED 1790 def_bool y 1791 depends on X86_PAT 1792 1793config X86_UMIP 1794 def_bool y 1795 prompt "User Mode Instruction Prevention" if EXPERT 1796 help 1797 User Mode Instruction Prevention (UMIP) is a security feature in 1798 some x86 processors. If enabled, a general protection fault is 1799 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1800 executed in user mode. These instructions unnecessarily expose 1801 information about the hardware state. 1802 1803 The vast majority of applications do not use these instructions. 1804 For the very few that do, software emulation is provided in 1805 specific cases in protected and virtual-8086 modes. Emulated 1806 results are dummy. 1807 1808config CC_HAS_IBT 1809 # GCC >= 9 and binutils >= 2.29 1810 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1811 # Clang/LLVM >= 14 1812 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1813 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1814 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1815 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1816 $(as-instr,endbr64) 1817 1818config X86_CET 1819 def_bool n 1820 help 1821 CET features configured (Shadow stack or IBT) 1822 1823config X86_KERNEL_IBT 1824 prompt "Indirect Branch Tracking" 1825 def_bool y 1826 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1827 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1828 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1829 select OBJTOOL 1830 select X86_CET 1831 help 1832 Build the kernel with support for Indirect Branch Tracking, a 1833 hardware support course-grain forward-edge Control Flow Integrity 1834 protection. It enforces that all indirect calls must land on 1835 an ENDBR instruction, as such, the compiler will instrument the 1836 code with them to make this happen. 1837 1838 In addition to building the kernel with IBT, seal all functions that 1839 are not indirect call targets, avoiding them ever becoming one. 1840 1841 This requires LTO like objtool runs and will slow down the build. It 1842 does significantly reduce the number of ENDBR instructions in the 1843 kernel image. 1844 1845config X86_INTEL_MEMORY_PROTECTION_KEYS 1846 prompt "Memory Protection Keys" 1847 def_bool y 1848 # Note: only available in 64-bit mode 1849 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1850 select ARCH_USES_HIGH_VMA_FLAGS 1851 select ARCH_HAS_PKEYS 1852 help 1853 Memory Protection Keys provides a mechanism for enforcing 1854 page-based protections, but without requiring modification of the 1855 page tables when an application changes protection domains. 1856 1857 For details, see Documentation/core-api/protection-keys.rst 1858 1859 If unsure, say y. 1860 1861choice 1862 prompt "TSX enable mode" 1863 depends on CPU_SUP_INTEL 1864 default X86_INTEL_TSX_MODE_OFF 1865 help 1866 Intel's TSX (Transactional Synchronization Extensions) feature 1867 allows to optimize locking protocols through lock elision which 1868 can lead to a noticeable performance boost. 1869 1870 On the other hand it has been shown that TSX can be exploited 1871 to form side channel attacks (e.g. TAA) and chances are there 1872 will be more of those attacks discovered in the future. 1873 1874 Therefore TSX is not enabled by default (aka tsx=off). An admin 1875 might override this decision by tsx=on the command line parameter. 1876 Even with TSX enabled, the kernel will attempt to enable the best 1877 possible TAA mitigation setting depending on the microcode available 1878 for the particular machine. 1879 1880 This option allows to set the default tsx mode between tsx=on, =off 1881 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1882 details. 1883 1884 Say off if not sure, auto if TSX is in use but it should be used on safe 1885 platforms or on if TSX is in use and the security aspect of tsx is not 1886 relevant. 1887 1888config X86_INTEL_TSX_MODE_OFF 1889 bool "off" 1890 help 1891 TSX is disabled if possible - equals to tsx=off command line parameter. 1892 1893config X86_INTEL_TSX_MODE_ON 1894 bool "on" 1895 help 1896 TSX is always enabled on TSX capable HW - equals the tsx=on command 1897 line parameter. 1898 1899config X86_INTEL_TSX_MODE_AUTO 1900 bool "auto" 1901 help 1902 TSX is enabled on TSX capable HW that is believed to be safe against 1903 side channel attacks- equals the tsx=auto command line parameter. 1904endchoice 1905 1906config X86_SGX 1907 bool "Software Guard eXtensions (SGX)" 1908 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1909 depends on CRYPTO=y 1910 depends on CRYPTO_SHA256=y 1911 select MMU_NOTIFIER 1912 select NUMA_KEEP_MEMINFO if NUMA 1913 select XARRAY_MULTI 1914 help 1915 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1916 that can be used by applications to set aside private regions of code 1917 and data, referred to as enclaves. An enclave's private memory can 1918 only be accessed by code running within the enclave. Accesses from 1919 outside the enclave, including other enclaves, are disallowed by 1920 hardware. 1921 1922 If unsure, say N. 1923 1924config X86_USER_SHADOW_STACK 1925 bool "X86 userspace shadow stack" 1926 depends on AS_WRUSS 1927 depends on X86_64 1928 select ARCH_USES_HIGH_VMA_FLAGS 1929 select X86_CET 1930 help 1931 Shadow stack protection is a hardware feature that detects function 1932 return address corruption. This helps mitigate ROP attacks. 1933 Applications must be enabled to use it, and old userspace does not 1934 get protection "for free". 1935 1936 CPUs supporting shadow stacks were first released in 2020. 1937 1938 See Documentation/arch/x86/shstk.rst for more information. 1939 1940 If unsure, say N. 1941 1942config EFI 1943 bool "EFI runtime service support" 1944 depends on ACPI 1945 select UCS2_STRING 1946 select EFI_RUNTIME_WRAPPERS 1947 select ARCH_USE_MEMREMAP_PROT 1948 select EFI_RUNTIME_MAP if KEXEC_CORE 1949 help 1950 This enables the kernel to use EFI runtime services that are 1951 available (such as the EFI variable services). 1952 1953 This option is only useful on systems that have EFI firmware. 1954 In addition, you should use the latest ELILO loader available 1955 at <http://elilo.sourceforge.net> in order to take advantage 1956 of EFI runtime services. However, even with this option, the 1957 resultant kernel should continue to boot on existing non-EFI 1958 platforms. 1959 1960config EFI_STUB 1961 bool "EFI stub support" 1962 depends on EFI 1963 select RELOCATABLE 1964 help 1965 This kernel feature allows a bzImage to be loaded directly 1966 by EFI firmware without the use of a bootloader. 1967 1968 See Documentation/admin-guide/efi-stub.rst for more information. 1969 1970config EFI_HANDOVER_PROTOCOL 1971 bool "EFI handover protocol (DEPRECATED)" 1972 depends on EFI_STUB 1973 default y 1974 help 1975 Select this in order to include support for the deprecated EFI 1976 handover protocol, which defines alternative entry points into the 1977 EFI stub. This is a practice that has no basis in the UEFI 1978 specification, and requires a priori knowledge on the part of the 1979 bootloader about Linux/x86 specific ways of passing the command line 1980 and initrd, and where in memory those assets may be loaded. 1981 1982 If in doubt, say Y. Even though the corresponding support is not 1983 present in upstream GRUB or other bootloaders, most distros build 1984 GRUB with numerous downstream patches applied, and may rely on the 1985 handover protocol as as result. 1986 1987config EFI_MIXED 1988 bool "EFI mixed-mode support" 1989 depends on EFI_STUB && X86_64 1990 help 1991 Enabling this feature allows a 64-bit kernel to be booted 1992 on a 32-bit firmware, provided that your CPU supports 64-bit 1993 mode. 1994 1995 Note that it is not possible to boot a mixed-mode enabled 1996 kernel via the EFI boot stub - a bootloader that supports 1997 the EFI handover protocol must be used. 1998 1999 If unsure, say N. 2000 2001config EFI_FAKE_MEMMAP 2002 bool "Enable EFI fake memory map" 2003 depends on EFI 2004 help 2005 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2006 this parameter, you can add arbitrary attribute to specific memory 2007 range by updating original (firmware provided) EFI memmap. This is 2008 useful for debugging of EFI memmap related feature, e.g., Address 2009 Range Mirroring feature. 2010 2011config EFI_MAX_FAKE_MEM 2012 int "maximum allowable number of ranges in efi_fake_mem boot option" 2013 depends on EFI_FAKE_MEMMAP 2014 range 1 128 2015 default 8 2016 help 2017 Maximum allowable number of ranges in efi_fake_mem boot option. 2018 Ranges can be set up to this value using comma-separated list. 2019 The default value is 8. 2020 2021config EFI_RUNTIME_MAP 2022 bool "Export EFI runtime maps to sysfs" if EXPERT 2023 depends on EFI 2024 help 2025 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2026 That memory map is required by the 2nd kernel to set up EFI virtual 2027 mappings after kexec, but can also be used for debugging purposes. 2028 2029 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2030 2031source "kernel/Kconfig.hz" 2032 2033config ARCH_SUPPORTS_KEXEC 2034 def_bool y 2035 2036config ARCH_SUPPORTS_KEXEC_FILE 2037 def_bool X86_64 && CRYPTO && CRYPTO_SHA256 2038 2039config ARCH_SELECTS_KEXEC_FILE 2040 def_bool y 2041 depends on KEXEC_FILE 2042 select HAVE_IMA_KEXEC if IMA 2043 2044config ARCH_SUPPORTS_KEXEC_PURGATORY 2045 def_bool KEXEC_FILE 2046 2047config ARCH_SUPPORTS_KEXEC_SIG 2048 def_bool y 2049 2050config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2051 def_bool y 2052 2053config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2054 def_bool y 2055 2056config ARCH_SUPPORTS_KEXEC_JUMP 2057 def_bool y 2058 2059config ARCH_SUPPORTS_CRASH_DUMP 2060 def_bool X86_64 || (X86_32 && HIGHMEM) 2061 2062config ARCH_SUPPORTS_CRASH_HOTPLUG 2063 def_bool y 2064 2065config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2066 def_bool CRASH_CORE 2067 2068config PHYSICAL_START 2069 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2070 default "0x1000000" 2071 help 2072 This gives the physical address where the kernel is loaded. 2073 2074 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2075 bzImage will decompress itself to above physical address and 2076 run from there. Otherwise, bzImage will run from the address where 2077 it has been loaded by the boot loader and will ignore above physical 2078 address. 2079 2080 In normal kdump cases one does not have to set/change this option 2081 as now bzImage can be compiled as a completely relocatable image 2082 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2083 address. This option is mainly useful for the folks who don't want 2084 to use a bzImage for capturing the crash dump and want to use a 2085 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2086 to be specifically compiled to run from a specific memory area 2087 (normally a reserved region) and this option comes handy. 2088 2089 So if you are using bzImage for capturing the crash dump, 2090 leave the value here unchanged to 0x1000000 and set 2091 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2092 for capturing the crash dump change this value to start of 2093 the reserved region. In other words, it can be set based on 2094 the "X" value as specified in the "crashkernel=YM@XM" 2095 command line boot parameter passed to the panic-ed 2096 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2097 for more details about crash dumps. 2098 2099 Usage of bzImage for capturing the crash dump is recommended as 2100 one does not have to build two kernels. Same kernel can be used 2101 as production kernel and capture kernel. Above option should have 2102 gone away after relocatable bzImage support is introduced. But it 2103 is present because there are users out there who continue to use 2104 vmlinux for dump capture. This option should go away down the 2105 line. 2106 2107 Don't change this unless you know what you are doing. 2108 2109config RELOCATABLE 2110 bool "Build a relocatable kernel" 2111 default y 2112 help 2113 This builds a kernel image that retains relocation information 2114 so it can be loaded someplace besides the default 1MB. 2115 The relocations tend to make the kernel binary about 10% larger, 2116 but are discarded at runtime. 2117 2118 One use is for the kexec on panic case where the recovery kernel 2119 must live at a different physical address than the primary 2120 kernel. 2121 2122 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2123 it has been loaded at and the compile time physical address 2124 (CONFIG_PHYSICAL_START) is used as the minimum location. 2125 2126config RANDOMIZE_BASE 2127 bool "Randomize the address of the kernel image (KASLR)" 2128 depends on RELOCATABLE 2129 default y 2130 help 2131 In support of Kernel Address Space Layout Randomization (KASLR), 2132 this randomizes the physical address at which the kernel image 2133 is decompressed and the virtual address where the kernel 2134 image is mapped, as a security feature that deters exploit 2135 attempts relying on knowledge of the location of kernel 2136 code internals. 2137 2138 On 64-bit, the kernel physical and virtual addresses are 2139 randomized separately. The physical address will be anywhere 2140 between 16MB and the top of physical memory (up to 64TB). The 2141 virtual address will be randomized from 16MB up to 1GB (9 bits 2142 of entropy). Note that this also reduces the memory space 2143 available to kernel modules from 1.5GB to 1GB. 2144 2145 On 32-bit, the kernel physical and virtual addresses are 2146 randomized together. They will be randomized from 16MB up to 2147 512MB (8 bits of entropy). 2148 2149 Entropy is generated using the RDRAND instruction if it is 2150 supported. If RDTSC is supported, its value is mixed into 2151 the entropy pool as well. If neither RDRAND nor RDTSC are 2152 supported, then entropy is read from the i8254 timer. The 2153 usable entropy is limited by the kernel being built using 2154 2GB addressing, and that PHYSICAL_ALIGN must be at a 2155 minimum of 2MB. As a result, only 10 bits of entropy are 2156 theoretically possible, but the implementations are further 2157 limited due to memory layouts. 2158 2159 If unsure, say Y. 2160 2161# Relocation on x86 needs some additional build support 2162config X86_NEED_RELOCS 2163 def_bool y 2164 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2165 2166config PHYSICAL_ALIGN 2167 hex "Alignment value to which kernel should be aligned" 2168 default "0x200000" 2169 range 0x2000 0x1000000 if X86_32 2170 range 0x200000 0x1000000 if X86_64 2171 help 2172 This value puts the alignment restrictions on physical address 2173 where kernel is loaded and run from. Kernel is compiled for an 2174 address which meets above alignment restriction. 2175 2176 If bootloader loads the kernel at a non-aligned address and 2177 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2178 address aligned to above value and run from there. 2179 2180 If bootloader loads the kernel at a non-aligned address and 2181 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2182 load address and decompress itself to the address it has been 2183 compiled for and run from there. The address for which kernel is 2184 compiled already meets above alignment restrictions. Hence the 2185 end result is that kernel runs from a physical address meeting 2186 above alignment restrictions. 2187 2188 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2189 this value must be a multiple of 0x200000. 2190 2191 Don't change this unless you know what you are doing. 2192 2193config DYNAMIC_MEMORY_LAYOUT 2194 bool 2195 help 2196 This option makes base addresses of vmalloc and vmemmap as well as 2197 __PAGE_OFFSET movable during boot. 2198 2199config RANDOMIZE_MEMORY 2200 bool "Randomize the kernel memory sections" 2201 depends on X86_64 2202 depends on RANDOMIZE_BASE 2203 select DYNAMIC_MEMORY_LAYOUT 2204 default RANDOMIZE_BASE 2205 help 2206 Randomizes the base virtual address of kernel memory sections 2207 (physical memory mapping, vmalloc & vmemmap). This security feature 2208 makes exploits relying on predictable memory locations less reliable. 2209 2210 The order of allocations remains unchanged. Entropy is generated in 2211 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2212 configuration have in average 30,000 different possible virtual 2213 addresses for each memory section. 2214 2215 If unsure, say Y. 2216 2217config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2218 hex "Physical memory mapping padding" if EXPERT 2219 depends on RANDOMIZE_MEMORY 2220 default "0xa" if MEMORY_HOTPLUG 2221 default "0x0" 2222 range 0x1 0x40 if MEMORY_HOTPLUG 2223 range 0x0 0x40 2224 help 2225 Define the padding in terabytes added to the existing physical 2226 memory size during kernel memory randomization. It is useful 2227 for memory hotplug support but reduces the entropy available for 2228 address randomization. 2229 2230 If unsure, leave at the default value. 2231 2232config ADDRESS_MASKING 2233 bool "Linear Address Masking support" 2234 depends on X86_64 2235 help 2236 Linear Address Masking (LAM) modifies the checking that is applied 2237 to 64-bit linear addresses, allowing software to use of the 2238 untranslated address bits for metadata. 2239 2240 The capability can be used for efficient address sanitizers (ASAN) 2241 implementation and for optimizations in JITs. 2242 2243config HOTPLUG_CPU 2244 def_bool y 2245 depends on SMP 2246 2247config COMPAT_VDSO 2248 def_bool n 2249 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2250 depends on COMPAT_32 2251 help 2252 Certain buggy versions of glibc will crash if they are 2253 presented with a 32-bit vDSO that is not mapped at the address 2254 indicated in its segment table. 2255 2256 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2257 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2258 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2259 the only released version with the bug, but OpenSUSE 9 2260 contains a buggy "glibc 2.3.2". 2261 2262 The symptom of the bug is that everything crashes on startup, saying: 2263 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2264 2265 Saying Y here changes the default value of the vdso32 boot 2266 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2267 This works around the glibc bug but hurts performance. 2268 2269 If unsure, say N: if you are compiling your own kernel, you 2270 are unlikely to be using a buggy version of glibc. 2271 2272choice 2273 prompt "vsyscall table for legacy applications" 2274 depends on X86_64 2275 default LEGACY_VSYSCALL_XONLY 2276 help 2277 Legacy user code that does not know how to find the vDSO expects 2278 to be able to issue three syscalls by calling fixed addresses in 2279 kernel space. Since this location is not randomized with ASLR, 2280 it can be used to assist security vulnerability exploitation. 2281 2282 This setting can be changed at boot time via the kernel command 2283 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2284 is deprecated and can only be enabled using the kernel command 2285 line. 2286 2287 On a system with recent enough glibc (2.14 or newer) and no 2288 static binaries, you can say None without a performance penalty 2289 to improve security. 2290 2291 If unsure, select "Emulate execution only". 2292 2293 config LEGACY_VSYSCALL_XONLY 2294 bool "Emulate execution only" 2295 help 2296 The kernel traps and emulates calls into the fixed vsyscall 2297 address mapping and does not allow reads. This 2298 configuration is recommended when userspace might use the 2299 legacy vsyscall area but support for legacy binary 2300 instrumentation of legacy code is not needed. It mitigates 2301 certain uses of the vsyscall area as an ASLR-bypassing 2302 buffer. 2303 2304 config LEGACY_VSYSCALL_NONE 2305 bool "None" 2306 help 2307 There will be no vsyscall mapping at all. This will 2308 eliminate any risk of ASLR bypass due to the vsyscall 2309 fixed address mapping. Attempts to use the vsyscalls 2310 will be reported to dmesg, so that either old or 2311 malicious userspace programs can be identified. 2312 2313endchoice 2314 2315config CMDLINE_BOOL 2316 bool "Built-in kernel command line" 2317 help 2318 Allow for specifying boot arguments to the kernel at 2319 build time. On some systems (e.g. embedded ones), it is 2320 necessary or convenient to provide some or all of the 2321 kernel boot arguments with the kernel itself (that is, 2322 to not rely on the boot loader to provide them.) 2323 2324 To compile command line arguments into the kernel, 2325 set this option to 'Y', then fill in the 2326 boot arguments in CONFIG_CMDLINE. 2327 2328 Systems with fully functional boot loaders (i.e. non-embedded) 2329 should leave this option set to 'N'. 2330 2331config CMDLINE 2332 string "Built-in kernel command string" 2333 depends on CMDLINE_BOOL 2334 default "" 2335 help 2336 Enter arguments here that should be compiled into the kernel 2337 image and used at boot time. If the boot loader provides a 2338 command line at boot time, it is appended to this string to 2339 form the full kernel command line, when the system boots. 2340 2341 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2342 change this behavior. 2343 2344 In most cases, the command line (whether built-in or provided 2345 by the boot loader) should specify the device for the root 2346 file system. 2347 2348config CMDLINE_OVERRIDE 2349 bool "Built-in command line overrides boot loader arguments" 2350 depends on CMDLINE_BOOL && CMDLINE != "" 2351 help 2352 Set this option to 'Y' to have the kernel ignore the boot loader 2353 command line, and use ONLY the built-in command line. 2354 2355 This is used to work around broken boot loaders. This should 2356 be set to 'N' under normal conditions. 2357 2358config MODIFY_LDT_SYSCALL 2359 bool "Enable the LDT (local descriptor table)" if EXPERT 2360 default y 2361 help 2362 Linux can allow user programs to install a per-process x86 2363 Local Descriptor Table (LDT) using the modify_ldt(2) system 2364 call. This is required to run 16-bit or segmented code such as 2365 DOSEMU or some Wine programs. It is also used by some very old 2366 threading libraries. 2367 2368 Enabling this feature adds a small amount of overhead to 2369 context switches and increases the low-level kernel attack 2370 surface. Disabling it removes the modify_ldt(2) system call. 2371 2372 Saying 'N' here may make sense for embedded or server kernels. 2373 2374config STRICT_SIGALTSTACK_SIZE 2375 bool "Enforce strict size checking for sigaltstack" 2376 depends on DYNAMIC_SIGFRAME 2377 help 2378 For historical reasons MINSIGSTKSZ is a constant which became 2379 already too small with AVX512 support. Add a mechanism to 2380 enforce strict checking of the sigaltstack size against the 2381 real size of the FPU frame. This option enables the check 2382 by default. It can also be controlled via the kernel command 2383 line option 'strict_sas_size' independent of this config 2384 switch. Enabling it might break existing applications which 2385 allocate a too small sigaltstack but 'work' because they 2386 never get a signal delivered. 2387 2388 Say 'N' unless you want to really enforce this check. 2389 2390source "kernel/livepatch/Kconfig" 2391 2392endmenu 2393 2394config CC_HAS_SLS 2395 def_bool $(cc-option,-mharden-sls=all) 2396 2397config CC_HAS_RETURN_THUNK 2398 def_bool $(cc-option,-mfunction-return=thunk-extern) 2399 2400config CC_HAS_ENTRY_PADDING 2401 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2402 2403config FUNCTION_PADDING_CFI 2404 int 2405 default 59 if FUNCTION_ALIGNMENT_64B 2406 default 27 if FUNCTION_ALIGNMENT_32B 2407 default 11 if FUNCTION_ALIGNMENT_16B 2408 default 3 if FUNCTION_ALIGNMENT_8B 2409 default 0 2410 2411# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2412# except Kconfig can't do arithmetic :/ 2413config FUNCTION_PADDING_BYTES 2414 int 2415 default FUNCTION_PADDING_CFI if CFI_CLANG 2416 default FUNCTION_ALIGNMENT 2417 2418config CALL_PADDING 2419 def_bool n 2420 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2421 select FUNCTION_ALIGNMENT_16B 2422 2423config FINEIBT 2424 def_bool y 2425 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE 2426 select CALL_PADDING 2427 2428config HAVE_CALL_THUNKS 2429 def_bool y 2430 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL 2431 2432config CALL_THUNKS 2433 def_bool n 2434 select CALL_PADDING 2435 2436config PREFIX_SYMBOLS 2437 def_bool y 2438 depends on CALL_PADDING && !CFI_CLANG 2439 2440menuconfig SPECULATION_MITIGATIONS 2441 bool "Mitigations for speculative execution vulnerabilities" 2442 default y 2443 help 2444 Say Y here to enable options which enable mitigations for 2445 speculative execution hardware vulnerabilities. 2446 2447 If you say N, all mitigations will be disabled. You really 2448 should know what you are doing to say so. 2449 2450if SPECULATION_MITIGATIONS 2451 2452config PAGE_TABLE_ISOLATION 2453 bool "Remove the kernel mapping in user mode" 2454 default y 2455 depends on (X86_64 || X86_PAE) 2456 help 2457 This feature reduces the number of hardware side channels by 2458 ensuring that the majority of kernel addresses are not mapped 2459 into userspace. 2460 2461 See Documentation/arch/x86/pti.rst for more details. 2462 2463config RETPOLINE 2464 bool "Avoid speculative indirect branches in kernel" 2465 select OBJTOOL if HAVE_OBJTOOL 2466 default y 2467 help 2468 Compile kernel with the retpoline compiler options to guard against 2469 kernel-to-user data leaks by avoiding speculative indirect 2470 branches. Requires a compiler with -mindirect-branch=thunk-extern 2471 support for full protection. The kernel may run slower. 2472 2473config RETHUNK 2474 bool "Enable return-thunks" 2475 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2476 select OBJTOOL if HAVE_OBJTOOL 2477 default y if X86_64 2478 help 2479 Compile the kernel with the return-thunks compiler option to guard 2480 against kernel-to-user data leaks by avoiding return speculation. 2481 Requires a compiler with -mfunction-return=thunk-extern 2482 support for full protection. The kernel may run slower. 2483 2484config CPU_UNRET_ENTRY 2485 bool "Enable UNRET on kernel entry" 2486 depends on CPU_SUP_AMD && RETHUNK && X86_64 2487 default y 2488 help 2489 Compile the kernel with support for the retbleed=unret mitigation. 2490 2491config CALL_DEPTH_TRACKING 2492 bool "Mitigate RSB underflow with call depth tracking" 2493 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2494 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2495 select CALL_THUNKS 2496 default y 2497 help 2498 Compile the kernel with call depth tracking to mitigate the Intel 2499 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2500 mitigation is off by default and needs to be enabled on the 2501 kernel command line via the retbleed=stuff option. For 2502 non-affected systems the overhead of this option is marginal as 2503 the call depth tracking is using run-time generated call thunks 2504 in a compiler generated padding area and call patching. This 2505 increases text size by ~5%. For non affected systems this space 2506 is unused. On affected SKL systems this results in a significant 2507 performance gain over the IBRS mitigation. 2508 2509config CALL_THUNKS_DEBUG 2510 bool "Enable call thunks and call depth tracking debugging" 2511 depends on CALL_DEPTH_TRACKING 2512 select FUNCTION_ALIGNMENT_32B 2513 default n 2514 help 2515 Enable call/ret counters for imbalance detection and build in 2516 a noisy dmesg about callthunks generation and call patching for 2517 trouble shooting. The debug prints need to be enabled on the 2518 kernel command line with 'debug-callthunks'. 2519 Only enable this when you are debugging call thunks as this 2520 creates a noticeable runtime overhead. If unsure say N. 2521 2522config CPU_IBPB_ENTRY 2523 bool "Enable IBPB on kernel entry" 2524 depends on CPU_SUP_AMD && X86_64 2525 default y 2526 help 2527 Compile the kernel with support for the retbleed=ibpb mitigation. 2528 2529config CPU_IBRS_ENTRY 2530 bool "Enable IBRS on kernel entry" 2531 depends on CPU_SUP_INTEL && X86_64 2532 default y 2533 help 2534 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2535 This mitigates both spectre_v2 and retbleed at great cost to 2536 performance. 2537 2538config CPU_SRSO 2539 bool "Mitigate speculative RAS overflow on AMD" 2540 depends on CPU_SUP_AMD && X86_64 && RETHUNK 2541 default y 2542 help 2543 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2544 2545config SLS 2546 bool "Mitigate Straight-Line-Speculation" 2547 depends on CC_HAS_SLS && X86_64 2548 select OBJTOOL if HAVE_OBJTOOL 2549 default n 2550 help 2551 Compile the kernel with straight-line-speculation options to guard 2552 against straight line speculation. The kernel image might be slightly 2553 larger. 2554 2555config GDS_FORCE_MITIGATION 2556 bool "Force GDS Mitigation" 2557 depends on CPU_SUP_INTEL 2558 default n 2559 help 2560 Gather Data Sampling (GDS) is a hardware vulnerability which allows 2561 unprivileged speculative access to data which was previously stored in 2562 vector registers. 2563 2564 This option is equivalent to setting gather_data_sampling=force on the 2565 command line. The microcode mitigation is used if present, otherwise 2566 AVX is disabled as a mitigation. On affected systems that are missing 2567 the microcode any userspace code that unconditionally uses AVX will 2568 break with this option set. 2569 2570 Setting this option on systems not vulnerable to GDS has no effect. 2571 2572 If in doubt, say N. 2573 2574endif 2575 2576config ARCH_HAS_ADD_PAGES 2577 def_bool y 2578 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2579 2580menu "Power management and ACPI options" 2581 2582config ARCH_HIBERNATION_HEADER 2583 def_bool y 2584 depends on HIBERNATION 2585 2586source "kernel/power/Kconfig" 2587 2588source "drivers/acpi/Kconfig" 2589 2590config X86_APM_BOOT 2591 def_bool y 2592 depends on APM 2593 2594menuconfig APM 2595 tristate "APM (Advanced Power Management) BIOS support" 2596 depends on X86_32 && PM_SLEEP 2597 help 2598 APM is a BIOS specification for saving power using several different 2599 techniques. This is mostly useful for battery powered laptops with 2600 APM compliant BIOSes. If you say Y here, the system time will be 2601 reset after a RESUME operation, the /proc/apm device will provide 2602 battery status information, and user-space programs will receive 2603 notification of APM "events" (e.g. battery status change). 2604 2605 If you select "Y" here, you can disable actual use of the APM 2606 BIOS by passing the "apm=off" option to the kernel at boot time. 2607 2608 Note that the APM support is almost completely disabled for 2609 machines with more than one CPU. 2610 2611 In order to use APM, you will need supporting software. For location 2612 and more information, read <file:Documentation/power/apm-acpi.rst> 2613 and the Battery Powered Linux mini-HOWTO, available from 2614 <http://www.tldp.org/docs.html#howto>. 2615 2616 This driver does not spin down disk drives (see the hdparm(8) 2617 manpage ("man 8 hdparm") for that), and it doesn't turn off 2618 VESA-compliant "green" monitors. 2619 2620 This driver does not support the TI 4000M TravelMate and the ACER 2621 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2622 desktop machines also don't have compliant BIOSes, and this driver 2623 may cause those machines to panic during the boot phase. 2624 2625 Generally, if you don't have a battery in your machine, there isn't 2626 much point in using this driver and you should say N. If you get 2627 random kernel OOPSes or reboots that don't seem to be related to 2628 anything, try disabling/enabling this option (or disabling/enabling 2629 APM in your BIOS). 2630 2631 Some other things you should try when experiencing seemingly random, 2632 "weird" problems: 2633 2634 1) make sure that you have enough swap space and that it is 2635 enabled. 2636 2) pass the "idle=poll" option to the kernel 2637 3) switch on floating point emulation in the kernel and pass 2638 the "no387" option to the kernel 2639 4) pass the "floppy=nodma" option to the kernel 2640 5) pass the "mem=4M" option to the kernel (thereby disabling 2641 all but the first 4 MB of RAM) 2642 6) make sure that the CPU is not over clocked. 2643 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2644 8) disable the cache from your BIOS settings 2645 9) install a fan for the video card or exchange video RAM 2646 10) install a better fan for the CPU 2647 11) exchange RAM chips 2648 12) exchange the motherboard. 2649 2650 To compile this driver as a module, choose M here: the 2651 module will be called apm. 2652 2653if APM 2654 2655config APM_IGNORE_USER_SUSPEND 2656 bool "Ignore USER SUSPEND" 2657 help 2658 This option will ignore USER SUSPEND requests. On machines with a 2659 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2660 series notebooks, it is necessary to say Y because of a BIOS bug. 2661 2662config APM_DO_ENABLE 2663 bool "Enable PM at boot time" 2664 help 2665 Enable APM features at boot time. From page 36 of the APM BIOS 2666 specification: "When disabled, the APM BIOS does not automatically 2667 power manage devices, enter the Standby State, enter the Suspend 2668 State, or take power saving steps in response to CPU Idle calls." 2669 This driver will make CPU Idle calls when Linux is idle (unless this 2670 feature is turned off -- see "Do CPU IDLE calls", below). This 2671 should always save battery power, but more complicated APM features 2672 will be dependent on your BIOS implementation. You may need to turn 2673 this option off if your computer hangs at boot time when using APM 2674 support, or if it beeps continuously instead of suspending. Turn 2675 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2676 T400CDT. This is off by default since most machines do fine without 2677 this feature. 2678 2679config APM_CPU_IDLE 2680 depends on CPU_IDLE 2681 bool "Make CPU Idle calls when idle" 2682 help 2683 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2684 On some machines, this can activate improved power savings, such as 2685 a slowed CPU clock rate, when the machine is idle. These idle calls 2686 are made after the idle loop has run for some length of time (e.g., 2687 333 mS). On some machines, this will cause a hang at boot time or 2688 whenever the CPU becomes idle. (On machines with more than one CPU, 2689 this option does nothing.) 2690 2691config APM_DISPLAY_BLANK 2692 bool "Enable console blanking using APM" 2693 help 2694 Enable console blanking using the APM. Some laptops can use this to 2695 turn off the LCD backlight when the screen blanker of the Linux 2696 virtual console blanks the screen. Note that this is only used by 2697 the virtual console screen blanker, and won't turn off the backlight 2698 when using the X Window system. This also doesn't have anything to 2699 do with your VESA-compliant power-saving monitor. Further, this 2700 option doesn't work for all laptops -- it might not turn off your 2701 backlight at all, or it might print a lot of errors to the console, 2702 especially if you are using gpm. 2703 2704config APM_ALLOW_INTS 2705 bool "Allow interrupts during APM BIOS calls" 2706 help 2707 Normally we disable external interrupts while we are making calls to 2708 the APM BIOS as a measure to lessen the effects of a badly behaving 2709 BIOS implementation. The BIOS should reenable interrupts if it 2710 needs to. Unfortunately, some BIOSes do not -- especially those in 2711 many of the newer IBM Thinkpads. If you experience hangs when you 2712 suspend, try setting this to Y. Otherwise, say N. 2713 2714endif # APM 2715 2716source "drivers/cpufreq/Kconfig" 2717 2718source "drivers/cpuidle/Kconfig" 2719 2720source "drivers/idle/Kconfig" 2721 2722endmenu 2723 2724menu "Bus options (PCI etc.)" 2725 2726choice 2727 prompt "PCI access mode" 2728 depends on X86_32 && PCI 2729 default PCI_GOANY 2730 help 2731 On PCI systems, the BIOS can be used to detect the PCI devices and 2732 determine their configuration. However, some old PCI motherboards 2733 have BIOS bugs and may crash if this is done. Also, some embedded 2734 PCI-based systems don't have any BIOS at all. Linux can also try to 2735 detect the PCI hardware directly without using the BIOS. 2736 2737 With this option, you can specify how Linux should detect the 2738 PCI devices. If you choose "BIOS", the BIOS will be used, 2739 if you choose "Direct", the BIOS won't be used, and if you 2740 choose "MMConfig", then PCI Express MMCONFIG will be used. 2741 If you choose "Any", the kernel will try MMCONFIG, then the 2742 direct access method and falls back to the BIOS if that doesn't 2743 work. If unsure, go with the default, which is "Any". 2744 2745config PCI_GOBIOS 2746 bool "BIOS" 2747 2748config PCI_GOMMCONFIG 2749 bool "MMConfig" 2750 2751config PCI_GODIRECT 2752 bool "Direct" 2753 2754config PCI_GOOLPC 2755 bool "OLPC XO-1" 2756 depends on OLPC 2757 2758config PCI_GOANY 2759 bool "Any" 2760 2761endchoice 2762 2763config PCI_BIOS 2764 def_bool y 2765 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2766 2767# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2768config PCI_DIRECT 2769 def_bool y 2770 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2771 2772config PCI_MMCONFIG 2773 bool "Support mmconfig PCI config space access" if X86_64 2774 default y 2775 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2776 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2777 2778config PCI_OLPC 2779 def_bool y 2780 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2781 2782config PCI_XEN 2783 def_bool y 2784 depends on PCI && XEN 2785 2786config MMCONF_FAM10H 2787 def_bool y 2788 depends on X86_64 && PCI_MMCONFIG && ACPI 2789 2790config PCI_CNB20LE_QUIRK 2791 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2792 depends on PCI 2793 help 2794 Read the PCI windows out of the CNB20LE host bridge. This allows 2795 PCI hotplug to work on systems with the CNB20LE chipset which do 2796 not have ACPI. 2797 2798 There's no public spec for this chipset, and this functionality 2799 is known to be incomplete. 2800 2801 You should say N unless you know you need this. 2802 2803config ISA_BUS 2804 bool "ISA bus support on modern systems" if EXPERT 2805 help 2806 Expose ISA bus device drivers and options available for selection and 2807 configuration. Enable this option if your target machine has an ISA 2808 bus. ISA is an older system, displaced by PCI and newer bus 2809 architectures -- if your target machine is modern, it probably does 2810 not have an ISA bus. 2811 2812 If unsure, say N. 2813 2814# x86_64 have no ISA slots, but can have ISA-style DMA. 2815config ISA_DMA_API 2816 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2817 default y 2818 help 2819 Enables ISA-style DMA support for devices requiring such controllers. 2820 If unsure, say Y. 2821 2822if X86_32 2823 2824config ISA 2825 bool "ISA support" 2826 help 2827 Find out whether you have ISA slots on your motherboard. ISA is the 2828 name of a bus system, i.e. the way the CPU talks to the other stuff 2829 inside your box. Other bus systems are PCI, EISA, MicroChannel 2830 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2831 newer boards don't support it. If you have ISA, say Y, otherwise N. 2832 2833config SCx200 2834 tristate "NatSemi SCx200 support" 2835 help 2836 This provides basic support for National Semiconductor's 2837 (now AMD's) Geode processors. The driver probes for the 2838 PCI-IDs of several on-chip devices, so its a good dependency 2839 for other scx200_* drivers. 2840 2841 If compiled as a module, the driver is named scx200. 2842 2843config SCx200HR_TIMER 2844 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2845 depends on SCx200 2846 default y 2847 help 2848 This driver provides a clocksource built upon the on-chip 2849 27MHz high-resolution timer. Its also a workaround for 2850 NSC Geode SC-1100's buggy TSC, which loses time when the 2851 processor goes idle (as is done by the scheduler). The 2852 other workaround is idle=poll boot option. 2853 2854config OLPC 2855 bool "One Laptop Per Child support" 2856 depends on !X86_PAE 2857 select GPIOLIB 2858 select OF 2859 select OF_PROMTREE 2860 select IRQ_DOMAIN 2861 select OLPC_EC 2862 help 2863 Add support for detecting the unique features of the OLPC 2864 XO hardware. 2865 2866config OLPC_XO1_PM 2867 bool "OLPC XO-1 Power Management" 2868 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2869 help 2870 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2871 2872config OLPC_XO1_RTC 2873 bool "OLPC XO-1 Real Time Clock" 2874 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2875 help 2876 Add support for the XO-1 real time clock, which can be used as a 2877 programmable wakeup source. 2878 2879config OLPC_XO1_SCI 2880 bool "OLPC XO-1 SCI extras" 2881 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2882 depends on INPUT=y 2883 select POWER_SUPPLY 2884 help 2885 Add support for SCI-based features of the OLPC XO-1 laptop: 2886 - EC-driven system wakeups 2887 - Power button 2888 - Ebook switch 2889 - Lid switch 2890 - AC adapter status updates 2891 - Battery status updates 2892 2893config OLPC_XO15_SCI 2894 bool "OLPC XO-1.5 SCI extras" 2895 depends on OLPC && ACPI 2896 select POWER_SUPPLY 2897 help 2898 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2899 - EC-driven system wakeups 2900 - AC adapter status updates 2901 - Battery status updates 2902 2903config ALIX 2904 bool "PCEngines ALIX System Support (LED setup)" 2905 select GPIOLIB 2906 help 2907 This option enables system support for the PCEngines ALIX. 2908 At present this just sets up LEDs for GPIO control on 2909 ALIX2/3/6 boards. However, other system specific setup should 2910 get added here. 2911 2912 Note: You must still enable the drivers for GPIO and LED support 2913 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2914 2915 Note: You have to set alix.force=1 for boards with Award BIOS. 2916 2917config NET5501 2918 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2919 select GPIOLIB 2920 help 2921 This option enables system support for the Soekris Engineering net5501. 2922 2923config GEOS 2924 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2925 select GPIOLIB 2926 depends on DMI 2927 help 2928 This option enables system support for the Traverse Technologies GEOS. 2929 2930config TS5500 2931 bool "Technologic Systems TS-5500 platform support" 2932 depends on MELAN 2933 select CHECK_SIGNATURE 2934 select NEW_LEDS 2935 select LEDS_CLASS 2936 help 2937 This option enables system support for the Technologic Systems TS-5500. 2938 2939endif # X86_32 2940 2941config AMD_NB 2942 def_bool y 2943 depends on CPU_SUP_AMD && PCI 2944 2945endmenu 2946 2947menu "Binary Emulations" 2948 2949config IA32_EMULATION 2950 bool "IA32 Emulation" 2951 depends on X86_64 2952 select ARCH_WANT_OLD_COMPAT_IPC 2953 select BINFMT_ELF 2954 select COMPAT_OLD_SIGACTION 2955 help 2956 Include code to run legacy 32-bit programs under a 2957 64-bit kernel. You should likely turn this on, unless you're 2958 100% sure that you don't have any 32-bit programs left. 2959 2960config X86_X32_ABI 2961 bool "x32 ABI for 64-bit mode" 2962 depends on X86_64 2963 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2964 # compressed debug sections to x86_x32 properly: 2965 # https://github.com/ClangBuiltLinux/linux/issues/514 2966 # https://github.com/ClangBuiltLinux/linux/issues/1141 2967 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 2968 help 2969 Include code to run binaries for the x32 native 32-bit ABI 2970 for 64-bit processors. An x32 process gets access to the 2971 full 64-bit register file and wide data path while leaving 2972 pointers at 32 bits for smaller memory footprint. 2973 2974config COMPAT_32 2975 def_bool y 2976 depends on IA32_EMULATION || X86_32 2977 select HAVE_UID16 2978 select OLD_SIGSUSPEND3 2979 2980config COMPAT 2981 def_bool y 2982 depends on IA32_EMULATION || X86_X32_ABI 2983 2984config COMPAT_FOR_U64_ALIGNMENT 2985 def_bool y 2986 depends on COMPAT 2987 2988endmenu 2989 2990config HAVE_ATOMIC_IOMAP 2991 def_bool y 2992 depends on X86_32 2993 2994source "arch/x86/kvm/Kconfig" 2995 2996source "arch/x86/Kconfig.assembler" 2997