1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select ARCH_USE_CMPXCHG_LOCKREF 32 select HAVE_ARCH_SOFT_DIRTY 33 select MODULES_USE_ELF_RELA 34 select NEED_DMA_MAP_STATE 35 select SWIOTLB 36 select ARCH_HAS_ELFCORE_COMPAT 37 select ZONE_DMA32 38 39config FORCE_DYNAMIC_FTRACE 40 def_bool y 41 depends on X86_32 42 depends on FUNCTION_TRACER 43 select DYNAMIC_FTRACE 44 help 45 We keep the static function tracing (!DYNAMIC_FTRACE) around 46 in order to test the non static function tracing in the 47 generic code, as other architectures still use it. But we 48 only need to keep it around for x86_64. No need to keep it 49 for x86_32. For x86_32, force DYNAMIC_FTRACE. 50# 51# Arch settings 52# 53# ( Note that options that are marked 'if X86_64' could in principle be 54# ported to 32-bit as well. ) 55# 56config X86 57 def_bool y 58 # 59 # Note: keep this list sorted alphabetically 60 # 61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 63 select ARCH_32BIT_OFF_T if X86_32 64 select ARCH_CLOCKSOURCE_INIT 65 select ARCH_CONFIGURES_CPU_MITIGATIONS 66 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 67 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 68 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 69 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 70 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 71 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 72 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 73 select ARCH_HAS_CACHE_LINE_SIZE 74 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 75 select ARCH_HAS_CPU_FINALIZE_INIT 76 select ARCH_HAS_CURRENT_STACK_POINTER 77 select ARCH_HAS_DEBUG_VIRTUAL 78 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 79 select ARCH_HAS_DEVMEM_IS_ALLOWED 80 select ARCH_HAS_EARLY_DEBUG if KGDB 81 select ARCH_HAS_ELF_RANDOMIZE 82 select ARCH_HAS_FAST_MULTIPLIER 83 select ARCH_HAS_FORTIFY_SOURCE 84 select ARCH_HAS_GCOV_PROFILE_ALL 85 select ARCH_HAS_KCOV if X86_64 86 select ARCH_HAS_MEM_ENCRYPT 87 select ARCH_HAS_MEMBARRIER_SYNC_CORE 88 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 89 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 90 select ARCH_HAS_PMEM_API if X86_64 91 select ARCH_HAS_PTE_DEVMAP if X86_64 92 select ARCH_HAS_PTE_SPECIAL 93 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 94 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 95 select ARCH_HAS_COPY_MC if X86_64 96 select ARCH_HAS_SET_MEMORY 97 select ARCH_HAS_SET_DIRECT_MAP 98 select ARCH_HAS_STRICT_KERNEL_RWX 99 select ARCH_HAS_STRICT_MODULE_RWX 100 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 101 select ARCH_HAS_SYSCALL_WRAPPER 102 select ARCH_HAS_UBSAN_SANITIZE_ALL 103 select ARCH_HAS_DEBUG_WX 104 select ARCH_HAS_ZONE_DMA_SET if EXPERT 105 select ARCH_HAVE_NMI_SAFE_CMPXCHG 106 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 107 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 108 select ARCH_MIGHT_HAVE_PC_PARPORT 109 select ARCH_MIGHT_HAVE_PC_SERIO 110 select ARCH_STACKWALK 111 select ARCH_SUPPORTS_ACPI 112 select ARCH_SUPPORTS_ATOMIC_RMW 113 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 114 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 115 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 116 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 117 select ARCH_SUPPORTS_CFI_CLANG if X86_64 118 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 119 select ARCH_SUPPORTS_LTO_CLANG 120 select ARCH_SUPPORTS_LTO_CLANG_THIN 121 select ARCH_USE_BUILTIN_BSWAP 122 select ARCH_USE_MEMTEST 123 select ARCH_USE_QUEUED_RWLOCKS 124 select ARCH_USE_QUEUED_SPINLOCKS 125 select ARCH_USE_SYM_ANNOTATIONS 126 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 127 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 128 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 129 select ARCH_WANTS_NO_INSTR 130 select ARCH_WANT_GENERAL_HUGETLB 131 select ARCH_WANT_HUGE_PMD_SHARE 132 select ARCH_WANT_LD_ORPHAN_WARN 133 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 134 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 135 select ARCH_WANTS_THP_SWAP if X86_64 136 select ARCH_HAS_PARANOID_L1D_FLUSH 137 select BUILDTIME_TABLE_SORT 138 select CLKEVT_I8253 139 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 140 select CLOCKSOURCE_WATCHDOG 141 # Word-size accesses may read uninitialized data past the trailing \0 142 # in strings and cause false KMSAN reports. 143 select DCACHE_WORD_ACCESS if !KMSAN 144 select DYNAMIC_SIGFRAME 145 select EDAC_ATOMIC_SCRUB 146 select EDAC_SUPPORT 147 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 148 select GENERIC_CLOCKEVENTS_MIN_ADJUST 149 select GENERIC_CMOS_UPDATE 150 select GENERIC_CPU_AUTOPROBE 151 select GENERIC_CPU_VULNERABILITIES 152 select GENERIC_EARLY_IOREMAP 153 select GENERIC_ENTRY 154 select GENERIC_IOMAP 155 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 156 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 157 select GENERIC_IRQ_MIGRATION if SMP 158 select GENERIC_IRQ_PROBE 159 select GENERIC_IRQ_RESERVATION_MODE 160 select GENERIC_IRQ_SHOW 161 select GENERIC_PENDING_IRQ if SMP 162 select GENERIC_PTDUMP 163 select GENERIC_SMP_IDLE_THREAD 164 select GENERIC_TIME_VSYSCALL 165 select GENERIC_GETTIMEOFDAY 166 select GENERIC_VDSO_TIME_NS 167 select GUP_GET_PXX_LOW_HIGH if X86_PAE 168 select HARDIRQS_SW_RESEND 169 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 170 select HAS_IOPORT 171 select HAVE_ACPI_APEI if ACPI 172 select HAVE_ACPI_APEI_NMI if ACPI 173 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 174 select HAVE_ARCH_AUDITSYSCALL 175 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 176 select HAVE_ARCH_HUGE_VMALLOC if X86_64 177 select HAVE_ARCH_JUMP_LABEL 178 select HAVE_ARCH_JUMP_LABEL_RELATIVE 179 select HAVE_ARCH_KASAN if X86_64 180 select HAVE_ARCH_KASAN_VMALLOC if X86_64 181 select HAVE_ARCH_KFENCE 182 select HAVE_ARCH_KMSAN if X86_64 183 select HAVE_ARCH_KGDB 184 select HAVE_ARCH_MMAP_RND_BITS if MMU 185 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 186 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 187 select HAVE_ARCH_PREL32_RELOCATIONS 188 select HAVE_ARCH_SECCOMP_FILTER 189 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 190 select HAVE_ARCH_STACKLEAK 191 select HAVE_ARCH_TRACEHOOK 192 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 193 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 194 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 195 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 196 select HAVE_ARCH_VMAP_STACK if X86_64 197 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 198 select HAVE_ARCH_WITHIN_STACK_FRAMES 199 select HAVE_ASM_MODVERSIONS 200 select HAVE_CMPXCHG_DOUBLE 201 select HAVE_CMPXCHG_LOCAL 202 select HAVE_CONTEXT_TRACKING_USER if X86_64 203 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 204 select HAVE_C_RECORDMCOUNT 205 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 206 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 207 select HAVE_BUILDTIME_MCOUNT_SORT 208 select HAVE_DEBUG_KMEMLEAK 209 select HAVE_DMA_CONTIGUOUS 210 select HAVE_DYNAMIC_FTRACE 211 select HAVE_DYNAMIC_FTRACE_WITH_REGS 212 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 213 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 214 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 215 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 216 select HAVE_EBPF_JIT 217 select HAVE_EFFICIENT_UNALIGNED_ACCESS 218 select HAVE_EISA if X86_32 219 select HAVE_EXIT_THREAD 220 select HAVE_FAST_GUP 221 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 222 select HAVE_FTRACE_MCOUNT_RECORD 223 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 224 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 225 select HAVE_FUNCTION_TRACER 226 select HAVE_GCC_PLUGINS 227 select HAVE_HW_BREAKPOINT 228 select HAVE_IOREMAP_PROT 229 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 230 select HAVE_IRQ_TIME_ACCOUNTING 231 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 232 select HAVE_KERNEL_BZIP2 233 select HAVE_KERNEL_GZIP 234 select HAVE_KERNEL_LZ4 235 select HAVE_KERNEL_LZMA 236 select HAVE_KERNEL_LZO 237 select HAVE_KERNEL_XZ 238 select HAVE_KERNEL_ZSTD 239 select HAVE_KPROBES 240 select HAVE_KPROBES_ON_FTRACE 241 select HAVE_FUNCTION_ERROR_INJECTION 242 select HAVE_KRETPROBES 243 select HAVE_RETHOOK 244 select HAVE_KVM 245 select HAVE_LIVEPATCH if X86_64 246 select HAVE_MIXED_BREAKPOINTS_REGS 247 select HAVE_MOD_ARCH_SPECIFIC 248 select HAVE_MOVE_PMD 249 select HAVE_MOVE_PUD 250 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 251 select HAVE_NMI 252 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 253 select HAVE_OBJTOOL if X86_64 254 select HAVE_OPTPROBES 255 select HAVE_PCSPKR_PLATFORM 256 select HAVE_PERF_EVENTS 257 select HAVE_PERF_EVENTS_NMI 258 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 259 select HAVE_PCI 260 select HAVE_PERF_REGS 261 select HAVE_PERF_USER_STACK_DUMP 262 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 263 select MMU_GATHER_MERGE_VMAS 264 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 265 select HAVE_REGS_AND_STACK_ACCESS_API 266 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 267 select HAVE_FUNCTION_ARG_ACCESS_API 268 select HAVE_SETUP_PER_CPU_AREA 269 select HAVE_SOFTIRQ_ON_OWN_STACK 270 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 271 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 272 select HAVE_STATIC_CALL 273 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 274 select HAVE_PREEMPT_DYNAMIC_CALL 275 select HAVE_RSEQ 276 select HAVE_RUST if X86_64 277 select HAVE_SYSCALL_TRACEPOINTS 278 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 279 select HAVE_UNSTABLE_SCHED_CLOCK 280 select HAVE_USER_RETURN_NOTIFIER 281 select HAVE_GENERIC_VDSO 282 select HOTPLUG_PARALLEL if SMP && X86_64 283 select HOTPLUG_SMT if SMP 284 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 285 select IRQ_FORCED_THREADING 286 select LOCK_MM_AND_FIND_VMA 287 select NEED_PER_CPU_EMBED_FIRST_CHUNK 288 select NEED_PER_CPU_PAGE_FIRST_CHUNK 289 select NEED_SG_DMA_LENGTH 290 select PCI_DOMAINS if PCI 291 select PCI_LOCKLESS_CONFIG if PCI 292 select PERF_EVENTS 293 select RTC_LIB 294 select RTC_MC146818_LIB 295 select SPARSE_IRQ 296 select SYSCTL_EXCEPTION_TRACE 297 select THREAD_INFO_IN_TASK 298 select TRACE_IRQFLAGS_SUPPORT 299 select TRACE_IRQFLAGS_NMI_SUPPORT 300 select USER_STACKTRACE_SUPPORT 301 select HAVE_ARCH_KCSAN if X86_64 302 select PROC_PID_ARCH_STATUS if PROC_FS 303 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 304 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 305 select FUNCTION_ALIGNMENT_4B 306 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 307 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 308 309config INSTRUCTION_DECODER 310 def_bool y 311 depends on KPROBES || PERF_EVENTS || UPROBES 312 313config OUTPUT_FORMAT 314 string 315 default "elf32-i386" if X86_32 316 default "elf64-x86-64" if X86_64 317 318config LOCKDEP_SUPPORT 319 def_bool y 320 321config STACKTRACE_SUPPORT 322 def_bool y 323 324config MMU 325 def_bool y 326 327config ARCH_MMAP_RND_BITS_MIN 328 default 28 if 64BIT 329 default 8 330 331config ARCH_MMAP_RND_BITS_MAX 332 default 32 if 64BIT 333 default 16 334 335config ARCH_MMAP_RND_COMPAT_BITS_MIN 336 default 8 337 338config ARCH_MMAP_RND_COMPAT_BITS_MAX 339 default 16 340 341config SBUS 342 bool 343 344config GENERIC_ISA_DMA 345 def_bool y 346 depends on ISA_DMA_API 347 348config GENERIC_CSUM 349 bool 350 default y if KMSAN || KASAN 351 352config GENERIC_BUG 353 def_bool y 354 depends on BUG 355 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 356 357config GENERIC_BUG_RELATIVE_POINTERS 358 bool 359 360config ARCH_MAY_HAVE_PC_FDC 361 def_bool y 362 depends on ISA_DMA_API 363 364config GENERIC_CALIBRATE_DELAY 365 def_bool y 366 367config ARCH_HAS_CPU_RELAX 368 def_bool y 369 370config ARCH_HIBERNATION_POSSIBLE 371 def_bool y 372 373config ARCH_SUSPEND_POSSIBLE 374 def_bool y 375 376config AUDIT_ARCH 377 def_bool y if X86_64 378 379config KASAN_SHADOW_OFFSET 380 hex 381 depends on KASAN 382 default 0xdffffc0000000000 383 384config HAVE_INTEL_TXT 385 def_bool y 386 depends on INTEL_IOMMU && ACPI 387 388config X86_32_SMP 389 def_bool y 390 depends on X86_32 && SMP 391 392config X86_64_SMP 393 def_bool y 394 depends on X86_64 && SMP 395 396config ARCH_SUPPORTS_UPROBES 397 def_bool y 398 399config FIX_EARLYCON_MEM 400 def_bool y 401 402config DYNAMIC_PHYSICAL_MASK 403 bool 404 405config PGTABLE_LEVELS 406 int 407 default 5 if X86_5LEVEL 408 default 4 if X86_64 409 default 3 if X86_PAE 410 default 2 411 412config CC_HAS_SANE_STACKPROTECTOR 413 bool 414 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 415 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 416 help 417 We have to make sure stack protector is unconditionally disabled if 418 the compiler produces broken code or if it does not let us control 419 the segment on 32-bit kernels. 420 421menu "Processor type and features" 422 423config SMP 424 bool "Symmetric multi-processing support" 425 help 426 This enables support for systems with more than one CPU. If you have 427 a system with only one CPU, say N. If you have a system with more 428 than one CPU, say Y. 429 430 If you say N here, the kernel will run on uni- and multiprocessor 431 machines, but will use only one CPU of a multiprocessor machine. If 432 you say Y here, the kernel will run on many, but not all, 433 uniprocessor machines. On a uniprocessor machine, the kernel 434 will run faster if you say N here. 435 436 Note that if you say Y here and choose architecture "586" or 437 "Pentium" under "Processor family", the kernel will not work on 486 438 architectures. Similarly, multiprocessor kernels for the "PPro" 439 architecture may not work on all Pentium based boards. 440 441 People using multiprocessor machines who say Y here should also say 442 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 443 Management" code will be disabled if you say Y here. 444 445 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 446 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 447 <http://www.tldp.org/docs.html#howto>. 448 449 If you don't know what to do here, say N. 450 451config X86_X2APIC 452 bool "Support x2apic" 453 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 454 help 455 This enables x2apic support on CPUs that have this feature. 456 457 This allows 32-bit apic IDs (so it can support very large systems), 458 and accesses the local apic via MSRs not via mmio. 459 460 Some Intel systems circa 2022 and later are locked into x2APIC mode 461 and can not fall back to the legacy APIC modes if SGX or TDX are 462 enabled in the BIOS. They will boot with very reduced functionality 463 without enabling this option. 464 465 If you don't know what to do here, say N. 466 467config X86_MPPARSE 468 bool "Enable MPS table" if ACPI 469 default y 470 depends on X86_LOCAL_APIC 471 help 472 For old smp systems that do not have proper acpi support. Newer systems 473 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 474 475config GOLDFISH 476 def_bool y 477 depends on X86_GOLDFISH 478 479config X86_CPU_RESCTRL 480 bool "x86 CPU resource control support" 481 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 482 select KERNFS 483 select PROC_CPU_RESCTRL if PROC_FS 484 help 485 Enable x86 CPU resource control support. 486 487 Provide support for the allocation and monitoring of system resources 488 usage by the CPU. 489 490 Intel calls this Intel Resource Director Technology 491 (Intel(R) RDT). More information about RDT can be found in the 492 Intel x86 Architecture Software Developer Manual. 493 494 AMD calls this AMD Platform Quality of Service (AMD QoS). 495 More information about AMD QoS can be found in the AMD64 Technology 496 Platform Quality of Service Extensions manual. 497 498 Say N if unsure. 499 500if X86_32 501config X86_BIGSMP 502 bool "Support for big SMP systems with more than 8 CPUs" 503 depends on SMP 504 help 505 This option is needed for the systems that have more than 8 CPUs. 506 507config X86_EXTENDED_PLATFORM 508 bool "Support for extended (non-PC) x86 platforms" 509 default y 510 help 511 If you disable this option then the kernel will only support 512 standard PC platforms. (which covers the vast majority of 513 systems out there.) 514 515 If you enable this option then you'll be able to select support 516 for the following (non-PC) 32 bit x86 platforms: 517 Goldfish (Android emulator) 518 AMD Elan 519 RDC R-321x SoC 520 SGI 320/540 (Visual Workstation) 521 STA2X11-based (e.g. Northville) 522 Moorestown MID devices 523 524 If you have one of these systems, or if you want to build a 525 generic distribution kernel, say Y here - otherwise say N. 526endif # X86_32 527 528if X86_64 529config X86_EXTENDED_PLATFORM 530 bool "Support for extended (non-PC) x86 platforms" 531 default y 532 help 533 If you disable this option then the kernel will only support 534 standard PC platforms. (which covers the vast majority of 535 systems out there.) 536 537 If you enable this option then you'll be able to select support 538 for the following (non-PC) 64 bit x86 platforms: 539 Numascale NumaChip 540 ScaleMP vSMP 541 SGI Ultraviolet 542 543 If you have one of these systems, or if you want to build a 544 generic distribution kernel, say Y here - otherwise say N. 545endif # X86_64 546# This is an alphabetically sorted list of 64 bit extended platforms 547# Please maintain the alphabetic order if and when there are additions 548config X86_NUMACHIP 549 bool "Numascale NumaChip" 550 depends on X86_64 551 depends on X86_EXTENDED_PLATFORM 552 depends on NUMA 553 depends on SMP 554 depends on X86_X2APIC 555 depends on PCI_MMCONFIG 556 help 557 Adds support for Numascale NumaChip large-SMP systems. Needed to 558 enable more than ~168 cores. 559 If you don't have one of these, you should say N here. 560 561config X86_VSMP 562 bool "ScaleMP vSMP" 563 select HYPERVISOR_GUEST 564 select PARAVIRT 565 depends on X86_64 && PCI 566 depends on X86_EXTENDED_PLATFORM 567 depends on SMP 568 help 569 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 570 supposed to run on these EM64T-based machines. Only choose this option 571 if you have one of these machines. 572 573config X86_UV 574 bool "SGI Ultraviolet" 575 depends on X86_64 576 depends on X86_EXTENDED_PLATFORM 577 depends on NUMA 578 depends on EFI 579 depends on KEXEC_CORE 580 depends on X86_X2APIC 581 depends on PCI 582 help 583 This option is needed in order to support SGI Ultraviolet systems. 584 If you don't have one of these, you should say N here. 585 586# Following is an alphabetically sorted list of 32 bit extended platforms 587# Please maintain the alphabetic order if and when there are additions 588 589config X86_GOLDFISH 590 bool "Goldfish (Virtual Platform)" 591 depends on X86_EXTENDED_PLATFORM 592 help 593 Enable support for the Goldfish virtual platform used primarily 594 for Android development. Unless you are building for the Android 595 Goldfish emulator say N here. 596 597config X86_INTEL_CE 598 bool "CE4100 TV platform" 599 depends on PCI 600 depends on PCI_GODIRECT 601 depends on X86_IO_APIC 602 depends on X86_32 603 depends on X86_EXTENDED_PLATFORM 604 select X86_REBOOTFIXUPS 605 select OF 606 select OF_EARLY_FLATTREE 607 help 608 Select for the Intel CE media processor (CE4100) SOC. 609 This option compiles in support for the CE4100 SOC for settop 610 boxes and media devices. 611 612config X86_INTEL_MID 613 bool "Intel MID platform support" 614 depends on X86_EXTENDED_PLATFORM 615 depends on X86_PLATFORM_DEVICES 616 depends on PCI 617 depends on X86_64 || (PCI_GOANY && X86_32) 618 depends on X86_IO_APIC 619 select I2C 620 select DW_APB_TIMER 621 select INTEL_SCU_PCI 622 help 623 Select to build a kernel capable of supporting Intel MID (Mobile 624 Internet Device) platform systems which do not have the PCI legacy 625 interfaces. If you are building for a PC class system say N here. 626 627 Intel MID platforms are based on an Intel processor and chipset which 628 consume less power than most of the x86 derivatives. 629 630config X86_INTEL_QUARK 631 bool "Intel Quark platform support" 632 depends on X86_32 633 depends on X86_EXTENDED_PLATFORM 634 depends on X86_PLATFORM_DEVICES 635 depends on X86_TSC 636 depends on PCI 637 depends on PCI_GOANY 638 depends on X86_IO_APIC 639 select IOSF_MBI 640 select INTEL_IMR 641 select COMMON_CLK 642 help 643 Select to include support for Quark X1000 SoC. 644 Say Y here if you have a Quark based system such as the Arduino 645 compatible Intel Galileo. 646 647config X86_INTEL_LPSS 648 bool "Intel Low Power Subsystem Support" 649 depends on X86 && ACPI && PCI 650 select COMMON_CLK 651 select PINCTRL 652 select IOSF_MBI 653 help 654 Select to build support for Intel Low Power Subsystem such as 655 found on Intel Lynxpoint PCH. Selecting this option enables 656 things like clock tree (common clock framework) and pincontrol 657 which are needed by the LPSS peripheral drivers. 658 659config X86_AMD_PLATFORM_DEVICE 660 bool "AMD ACPI2Platform devices support" 661 depends on ACPI 662 select COMMON_CLK 663 select PINCTRL 664 help 665 Select to interpret AMD specific ACPI device to platform device 666 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 667 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 668 implemented under PINCTRL subsystem. 669 670config IOSF_MBI 671 tristate "Intel SoC IOSF Sideband support for SoC platforms" 672 depends on PCI 673 help 674 This option enables sideband register access support for Intel SoC 675 platforms. On these platforms the IOSF sideband is used in lieu of 676 MSR's for some register accesses, mostly but not limited to thermal 677 and power. Drivers may query the availability of this device to 678 determine if they need the sideband in order to work on these 679 platforms. The sideband is available on the following SoC products. 680 This list is not meant to be exclusive. 681 - BayTrail 682 - Braswell 683 - Quark 684 685 You should say Y if you are running a kernel on one of these SoC's. 686 687config IOSF_MBI_DEBUG 688 bool "Enable IOSF sideband access through debugfs" 689 depends on IOSF_MBI && DEBUG_FS 690 help 691 Select this option to expose the IOSF sideband access registers (MCR, 692 MDR, MCRX) through debugfs to write and read register information from 693 different units on the SoC. This is most useful for obtaining device 694 state information for debug and analysis. As this is a general access 695 mechanism, users of this option would have specific knowledge of the 696 device they want to access. 697 698 If you don't require the option or are in doubt, say N. 699 700config X86_RDC321X 701 bool "RDC R-321x SoC" 702 depends on X86_32 703 depends on X86_EXTENDED_PLATFORM 704 select M486 705 select X86_REBOOTFIXUPS 706 help 707 This option is needed for RDC R-321x system-on-chip, also known 708 as R-8610-(G). 709 If you don't have one of these chips, you should say N here. 710 711config X86_32_NON_STANDARD 712 bool "Support non-standard 32-bit SMP architectures" 713 depends on X86_32 && SMP 714 depends on X86_EXTENDED_PLATFORM 715 help 716 This option compiles in the bigsmp and STA2X11 default 717 subarchitectures. It is intended for a generic binary 718 kernel. If you select them all, kernel will probe it one by 719 one and will fallback to default. 720 721# Alphabetically sorted list of Non standard 32 bit platforms 722 723config X86_SUPPORTS_MEMORY_FAILURE 724 def_bool y 725 # MCE code calls memory_failure(): 726 depends on X86_MCE 727 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 728 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 729 depends on X86_64 || !SPARSEMEM 730 select ARCH_SUPPORTS_MEMORY_FAILURE 731 732config STA2X11 733 bool "STA2X11 Companion Chip Support" 734 depends on X86_32_NON_STANDARD && PCI 735 select SWIOTLB 736 select MFD_STA2X11 737 select GPIOLIB 738 help 739 This adds support for boards based on the STA2X11 IO-Hub, 740 a.k.a. "ConneXt". The chip is used in place of the standard 741 PC chipset, so all "standard" peripherals are missing. If this 742 option is selected the kernel will still be able to boot on 743 standard PC machines. 744 745config X86_32_IRIS 746 tristate "Eurobraille/Iris poweroff module" 747 depends on X86_32 748 help 749 The Iris machines from EuroBraille do not have APM or ACPI support 750 to shut themselves down properly. A special I/O sequence is 751 needed to do so, which is what this module does at 752 kernel shutdown. 753 754 This is only for Iris machines from EuroBraille. 755 756 If unused, say N. 757 758config SCHED_OMIT_FRAME_POINTER 759 def_bool y 760 prompt "Single-depth WCHAN output" 761 depends on X86 762 help 763 Calculate simpler /proc/<PID>/wchan values. If this option 764 is disabled then wchan values will recurse back to the 765 caller function. This provides more accurate wchan values, 766 at the expense of slightly more scheduling overhead. 767 768 If in doubt, say "Y". 769 770menuconfig HYPERVISOR_GUEST 771 bool "Linux guest support" 772 help 773 Say Y here to enable options for running Linux under various hyper- 774 visors. This option enables basic hypervisor detection and platform 775 setup. 776 777 If you say N, all options in this submenu will be skipped and 778 disabled, and Linux guest support won't be built in. 779 780if HYPERVISOR_GUEST 781 782config PARAVIRT 783 bool "Enable paravirtualization code" 784 depends on HAVE_STATIC_CALL 785 help 786 This changes the kernel so it can modify itself when it is run 787 under a hypervisor, potentially improving performance significantly 788 over full virtualization. However, when run without a hypervisor 789 the kernel is theoretically slower and slightly larger. 790 791config PARAVIRT_XXL 792 bool 793 794config PARAVIRT_DEBUG 795 bool "paravirt-ops debugging" 796 depends on PARAVIRT && DEBUG_KERNEL 797 help 798 Enable to debug paravirt_ops internals. Specifically, BUG if 799 a paravirt_op is missing when it is called. 800 801config PARAVIRT_SPINLOCKS 802 bool "Paravirtualization layer for spinlocks" 803 depends on PARAVIRT && SMP 804 help 805 Paravirtualized spinlocks allow a pvops backend to replace the 806 spinlock implementation with something virtualization-friendly 807 (for example, block the virtual CPU rather than spinning). 808 809 It has a minimal impact on native kernels and gives a nice performance 810 benefit on paravirtualized KVM / Xen kernels. 811 812 If you are unsure how to answer this question, answer Y. 813 814config X86_HV_CALLBACK_VECTOR 815 def_bool n 816 817source "arch/x86/xen/Kconfig" 818 819config KVM_GUEST 820 bool "KVM Guest support (including kvmclock)" 821 depends on PARAVIRT 822 select PARAVIRT_CLOCK 823 select ARCH_CPUIDLE_HALTPOLL 824 select X86_HV_CALLBACK_VECTOR 825 default y 826 help 827 This option enables various optimizations for running under the KVM 828 hypervisor. It includes a paravirtualized clock, so that instead 829 of relying on a PIT (or probably other) emulation by the 830 underlying device model, the host provides the guest with 831 timing infrastructure such as time of day, and system time 832 833config ARCH_CPUIDLE_HALTPOLL 834 def_bool n 835 prompt "Disable host haltpoll when loading haltpoll driver" 836 help 837 If virtualized under KVM, disable host haltpoll. 838 839config PVH 840 bool "Support for running PVH guests" 841 help 842 This option enables the PVH entry point for guest virtual machines 843 as specified in the x86/HVM direct boot ABI. 844 845config PARAVIRT_TIME_ACCOUNTING 846 bool "Paravirtual steal time accounting" 847 depends on PARAVIRT 848 help 849 Select this option to enable fine granularity task steal time 850 accounting. Time spent executing other tasks in parallel with 851 the current vCPU is discounted from the vCPU power. To account for 852 that, there can be a small performance impact. 853 854 If in doubt, say N here. 855 856config PARAVIRT_CLOCK 857 bool 858 859config JAILHOUSE_GUEST 860 bool "Jailhouse non-root cell support" 861 depends on X86_64 && PCI 862 select X86_PM_TIMER 863 help 864 This option allows to run Linux as guest in a Jailhouse non-root 865 cell. You can leave this option disabled if you only want to start 866 Jailhouse and run Linux afterwards in the root cell. 867 868config ACRN_GUEST 869 bool "ACRN Guest support" 870 depends on X86_64 871 select X86_HV_CALLBACK_VECTOR 872 help 873 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 874 a flexible, lightweight reference open-source hypervisor, built with 875 real-time and safety-criticality in mind. It is built for embedded 876 IOT with small footprint and real-time features. More details can be 877 found in https://projectacrn.org/. 878 879config INTEL_TDX_GUEST 880 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 881 depends on X86_64 && CPU_SUP_INTEL 882 depends on X86_X2APIC 883 depends on EFI_STUB 884 depends on PARAVIRT 885 select ARCH_HAS_CC_PLATFORM 886 select X86_MEM_ENCRYPT 887 select X86_MCE 888 select UNACCEPTED_MEMORY 889 help 890 Support running as a guest under Intel TDX. Without this support, 891 the guest kernel can not boot or run under TDX. 892 TDX includes memory encryption and integrity capabilities 893 which protect the confidentiality and integrity of guest 894 memory contents and CPU state. TDX guests are protected from 895 some attacks from the VMM. 896 897endif # HYPERVISOR_GUEST 898 899source "arch/x86/Kconfig.cpu" 900 901config HPET_TIMER 902 def_bool X86_64 903 prompt "HPET Timer Support" if X86_32 904 help 905 Use the IA-PC HPET (High Precision Event Timer) to manage 906 time in preference to the PIT and RTC, if a HPET is 907 present. 908 HPET is the next generation timer replacing legacy 8254s. 909 The HPET provides a stable time base on SMP 910 systems, unlike the TSC, but it is more expensive to access, 911 as it is off-chip. The interface used is documented 912 in the HPET spec, revision 1. 913 914 You can safely choose Y here. However, HPET will only be 915 activated if the platform and the BIOS support this feature. 916 Otherwise the 8254 will be used for timing services. 917 918 Choose N to continue using the legacy 8254 timer. 919 920config HPET_EMULATE_RTC 921 def_bool y 922 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 923 924# Mark as expert because too many people got it wrong. 925# The code disables itself when not needed. 926config DMI 927 default y 928 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 929 bool "Enable DMI scanning" if EXPERT 930 help 931 Enabled scanning of DMI to identify machine quirks. Say Y 932 here unless you have verified that your setup is not 933 affected by entries in the DMI blacklist. Required by PNP 934 BIOS code. 935 936config GART_IOMMU 937 bool "Old AMD GART IOMMU support" 938 select DMA_OPS 939 select IOMMU_HELPER 940 select SWIOTLB 941 depends on X86_64 && PCI && AMD_NB 942 help 943 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 944 GART based hardware IOMMUs. 945 946 The GART supports full DMA access for devices with 32-bit access 947 limitations, on systems with more than 3 GB. This is usually needed 948 for USB, sound, many IDE/SATA chipsets and some other devices. 949 950 Newer systems typically have a modern AMD IOMMU, supported via 951 the CONFIG_AMD_IOMMU=y config option. 952 953 In normal configurations this driver is only active when needed: 954 there's more than 3 GB of memory and the system contains a 955 32-bit limited device. 956 957 If unsure, say Y. 958 959config BOOT_VESA_SUPPORT 960 bool 961 help 962 If true, at least one selected framebuffer driver can take advantage 963 of VESA video modes set at an early boot stage via the vga= parameter. 964 965config MAXSMP 966 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 967 depends on X86_64 && SMP && DEBUG_KERNEL 968 select CPUMASK_OFFSTACK 969 help 970 Enable maximum number of CPUS and NUMA Nodes for this architecture. 971 If unsure, say N. 972 973# 974# The maximum number of CPUs supported: 975# 976# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 977# and which can be configured interactively in the 978# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 979# 980# The ranges are different on 32-bit and 64-bit kernels, depending on 981# hardware capabilities and scalability features of the kernel. 982# 983# ( If MAXSMP is enabled we just use the highest possible value and disable 984# interactive configuration. ) 985# 986 987config NR_CPUS_RANGE_BEGIN 988 int 989 default NR_CPUS_RANGE_END if MAXSMP 990 default 1 if !SMP 991 default 2 992 993config NR_CPUS_RANGE_END 994 int 995 depends on X86_32 996 default 64 if SMP && X86_BIGSMP 997 default 8 if SMP && !X86_BIGSMP 998 default 1 if !SMP 999 1000config NR_CPUS_RANGE_END 1001 int 1002 depends on X86_64 1003 default 8192 if SMP && CPUMASK_OFFSTACK 1004 default 512 if SMP && !CPUMASK_OFFSTACK 1005 default 1 if !SMP 1006 1007config NR_CPUS_DEFAULT 1008 int 1009 depends on X86_32 1010 default 32 if X86_BIGSMP 1011 default 8 if SMP 1012 default 1 if !SMP 1013 1014config NR_CPUS_DEFAULT 1015 int 1016 depends on X86_64 1017 default 8192 if MAXSMP 1018 default 64 if SMP 1019 default 1 if !SMP 1020 1021config NR_CPUS 1022 int "Maximum number of CPUs" if SMP && !MAXSMP 1023 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1024 default NR_CPUS_DEFAULT 1025 help 1026 This allows you to specify the maximum number of CPUs which this 1027 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1028 supported value is 8192, otherwise the maximum value is 512. The 1029 minimum value which makes sense is 2. 1030 1031 This is purely to save memory: each supported CPU adds about 8KB 1032 to the kernel image. 1033 1034config SCHED_CLUSTER 1035 bool "Cluster scheduler support" 1036 depends on SMP 1037 default y 1038 help 1039 Cluster scheduler support improves the CPU scheduler's decision 1040 making when dealing with machines that have clusters of CPUs. 1041 Cluster usually means a couple of CPUs which are placed closely 1042 by sharing mid-level caches, last-level cache tags or internal 1043 busses. 1044 1045config SCHED_SMT 1046 def_bool y if SMP 1047 1048config SCHED_MC 1049 def_bool y 1050 prompt "Multi-core scheduler support" 1051 depends on SMP 1052 help 1053 Multi-core scheduler support improves the CPU scheduler's decision 1054 making when dealing with multi-core CPU chips at a cost of slightly 1055 increased overhead in some places. If unsure say N here. 1056 1057config SCHED_MC_PRIO 1058 bool "CPU core priorities scheduler support" 1059 depends on SCHED_MC && CPU_SUP_INTEL 1060 select X86_INTEL_PSTATE 1061 select CPU_FREQ 1062 default y 1063 help 1064 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1065 core ordering determined at manufacturing time, which allows 1066 certain cores to reach higher turbo frequencies (when running 1067 single threaded workloads) than others. 1068 1069 Enabling this kernel feature teaches the scheduler about 1070 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1071 scheduler's CPU selection logic accordingly, so that higher 1072 overall system performance can be achieved. 1073 1074 This feature will have no effect on CPUs without this feature. 1075 1076 If unsure say Y here. 1077 1078config UP_LATE_INIT 1079 def_bool y 1080 depends on !SMP && X86_LOCAL_APIC 1081 1082config X86_UP_APIC 1083 bool "Local APIC support on uniprocessors" if !PCI_MSI 1084 default PCI_MSI 1085 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1086 help 1087 A local APIC (Advanced Programmable Interrupt Controller) is an 1088 integrated interrupt controller in the CPU. If you have a single-CPU 1089 system which has a processor with a local APIC, you can say Y here to 1090 enable and use it. If you say Y here even though your machine doesn't 1091 have a local APIC, then the kernel will still run with no slowdown at 1092 all. The local APIC supports CPU-generated self-interrupts (timer, 1093 performance counters), and the NMI watchdog which detects hard 1094 lockups. 1095 1096config X86_UP_IOAPIC 1097 bool "IO-APIC support on uniprocessors" 1098 depends on X86_UP_APIC 1099 help 1100 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1101 SMP-capable replacement for PC-style interrupt controllers. Most 1102 SMP systems and many recent uniprocessor systems have one. 1103 1104 If you have a single-CPU system with an IO-APIC, you can say Y here 1105 to use it. If you say Y here even though your machine doesn't have 1106 an IO-APIC, then the kernel will still run with no slowdown at all. 1107 1108config X86_LOCAL_APIC 1109 def_bool y 1110 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1111 select IRQ_DOMAIN_HIERARCHY 1112 1113config X86_IO_APIC 1114 def_bool y 1115 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1116 1117config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1118 bool "Reroute for broken boot IRQs" 1119 depends on X86_IO_APIC 1120 help 1121 This option enables a workaround that fixes a source of 1122 spurious interrupts. This is recommended when threaded 1123 interrupt handling is used on systems where the generation of 1124 superfluous "boot interrupts" cannot be disabled. 1125 1126 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1127 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1128 kernel does during interrupt handling). On chipsets where this 1129 boot IRQ generation cannot be disabled, this workaround keeps 1130 the original IRQ line masked so that only the equivalent "boot 1131 IRQ" is delivered to the CPUs. The workaround also tells the 1132 kernel to set up the IRQ handler on the boot IRQ line. In this 1133 way only one interrupt is delivered to the kernel. Otherwise 1134 the spurious second interrupt may cause the kernel to bring 1135 down (vital) interrupt lines. 1136 1137 Only affects "broken" chipsets. Interrupt sharing may be 1138 increased on these systems. 1139 1140config X86_MCE 1141 bool "Machine Check / overheating reporting" 1142 select GENERIC_ALLOCATOR 1143 default y 1144 help 1145 Machine Check support allows the processor to notify the 1146 kernel if it detects a problem (e.g. overheating, data corruption). 1147 The action the kernel takes depends on the severity of the problem, 1148 ranging from warning messages to halting the machine. 1149 1150config X86_MCELOG_LEGACY 1151 bool "Support for deprecated /dev/mcelog character device" 1152 depends on X86_MCE 1153 help 1154 Enable support for /dev/mcelog which is needed by the old mcelog 1155 userspace logging daemon. Consider switching to the new generation 1156 rasdaemon solution. 1157 1158config X86_MCE_INTEL 1159 def_bool y 1160 prompt "Intel MCE features" 1161 depends on X86_MCE && X86_LOCAL_APIC 1162 help 1163 Additional support for intel specific MCE features such as 1164 the thermal monitor. 1165 1166config X86_MCE_AMD 1167 def_bool y 1168 prompt "AMD MCE features" 1169 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1170 help 1171 Additional support for AMD specific MCE features such as 1172 the DRAM Error Threshold. 1173 1174config X86_ANCIENT_MCE 1175 bool "Support for old Pentium 5 / WinChip machine checks" 1176 depends on X86_32 && X86_MCE 1177 help 1178 Include support for machine check handling on old Pentium 5 or WinChip 1179 systems. These typically need to be enabled explicitly on the command 1180 line. 1181 1182config X86_MCE_THRESHOLD 1183 depends on X86_MCE_AMD || X86_MCE_INTEL 1184 def_bool y 1185 1186config X86_MCE_INJECT 1187 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1188 tristate "Machine check injector support" 1189 help 1190 Provide support for injecting machine checks for testing purposes. 1191 If you don't know what a machine check is and you don't do kernel 1192 QA it is safe to say n. 1193 1194source "arch/x86/events/Kconfig" 1195 1196config X86_LEGACY_VM86 1197 bool "Legacy VM86 support" 1198 depends on X86_32 1199 help 1200 This option allows user programs to put the CPU into V8086 1201 mode, which is an 80286-era approximation of 16-bit real mode. 1202 1203 Some very old versions of X and/or vbetool require this option 1204 for user mode setting. Similarly, DOSEMU will use it if 1205 available to accelerate real mode DOS programs. However, any 1206 recent version of DOSEMU, X, or vbetool should be fully 1207 functional even without kernel VM86 support, as they will all 1208 fall back to software emulation. Nevertheless, if you are using 1209 a 16-bit DOS program where 16-bit performance matters, vm86 1210 mode might be faster than emulation and you might want to 1211 enable this option. 1212 1213 Note that any app that works on a 64-bit kernel is unlikely to 1214 need this option, as 64-bit kernels don't, and can't, support 1215 V8086 mode. This option is also unrelated to 16-bit protected 1216 mode and is not needed to run most 16-bit programs under Wine. 1217 1218 Enabling this option increases the complexity of the kernel 1219 and slows down exception handling a tiny bit. 1220 1221 If unsure, say N here. 1222 1223config VM86 1224 bool 1225 default X86_LEGACY_VM86 1226 1227config X86_16BIT 1228 bool "Enable support for 16-bit segments" if EXPERT 1229 default y 1230 depends on MODIFY_LDT_SYSCALL 1231 help 1232 This option is required by programs like Wine to run 16-bit 1233 protected mode legacy code on x86 processors. Disabling 1234 this option saves about 300 bytes on i386, or around 6K text 1235 plus 16K runtime memory on x86-64, 1236 1237config X86_ESPFIX32 1238 def_bool y 1239 depends on X86_16BIT && X86_32 1240 1241config X86_ESPFIX64 1242 def_bool y 1243 depends on X86_16BIT && X86_64 1244 1245config X86_VSYSCALL_EMULATION 1246 bool "Enable vsyscall emulation" if EXPERT 1247 default y 1248 depends on X86_64 1249 help 1250 This enables emulation of the legacy vsyscall page. Disabling 1251 it is roughly equivalent to booting with vsyscall=none, except 1252 that it will also disable the helpful warning if a program 1253 tries to use a vsyscall. With this option set to N, offending 1254 programs will just segfault, citing addresses of the form 1255 0xffffffffff600?00. 1256 1257 This option is required by many programs built before 2013, and 1258 care should be used even with newer programs if set to N. 1259 1260 Disabling this option saves about 7K of kernel size and 1261 possibly 4K of additional runtime pagetable memory. 1262 1263config X86_IOPL_IOPERM 1264 bool "IOPERM and IOPL Emulation" 1265 default y 1266 help 1267 This enables the ioperm() and iopl() syscalls which are necessary 1268 for legacy applications. 1269 1270 Legacy IOPL support is an overbroad mechanism which allows user 1271 space aside of accessing all 65536 I/O ports also to disable 1272 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1273 capabilities and permission from potentially active security 1274 modules. 1275 1276 The emulation restricts the functionality of the syscall to 1277 only allowing the full range I/O port access, but prevents the 1278 ability to disable interrupts from user space which would be 1279 granted if the hardware IOPL mechanism would be used. 1280 1281config TOSHIBA 1282 tristate "Toshiba Laptop support" 1283 depends on X86_32 1284 help 1285 This adds a driver to safely access the System Management Mode of 1286 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1287 not work on models with a Phoenix BIOS. The System Management Mode 1288 is used to set the BIOS and power saving options on Toshiba portables. 1289 1290 For information on utilities to make use of this driver see the 1291 Toshiba Linux utilities web site at: 1292 <http://www.buzzard.org.uk/toshiba/>. 1293 1294 Say Y if you intend to run this kernel on a Toshiba portable. 1295 Say N otherwise. 1296 1297config X86_REBOOTFIXUPS 1298 bool "Enable X86 board specific fixups for reboot" 1299 depends on X86_32 1300 help 1301 This enables chipset and/or board specific fixups to be done 1302 in order to get reboot to work correctly. This is only needed on 1303 some combinations of hardware and BIOS. The symptom, for which 1304 this config is intended, is when reboot ends with a stalled/hung 1305 system. 1306 1307 Currently, the only fixup is for the Geode machines using 1308 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1309 1310 Say Y if you want to enable the fixup. Currently, it's safe to 1311 enable this option even if you don't need it. 1312 Say N otherwise. 1313 1314config MICROCODE 1315 def_bool y 1316 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1317 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD 1318 1319config MICROCODE_INITRD32 1320 def_bool y 1321 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1322 1323config MICROCODE_LATE_LOADING 1324 bool "Late microcode loading (DANGEROUS)" 1325 default n 1326 depends on MICROCODE && SMP 1327 help 1328 Loading microcode late, when the system is up and executing instructions 1329 is a tricky business and should be avoided if possible. Just the sequence 1330 of synchronizing all cores and SMT threads is one fragile dance which does 1331 not guarantee that cores might not softlock after the loading. Therefore, 1332 use this at your own risk. Late loading taints the kernel unless the 1333 microcode header indicates that it is safe for late loading via the 1334 minimal revision check. This minimal revision check can be enforced on 1335 the kernel command line with "microcode.minrev=Y". 1336 1337config MICROCODE_LATE_FORCE_MINREV 1338 bool "Enforce late microcode loading minimal revision check" 1339 default n 1340 depends on MICROCODE_LATE_LOADING 1341 help 1342 To prevent that users load microcode late which modifies already 1343 in use features, newer microcode patches have a minimum revision field 1344 in the microcode header, which tells the kernel which minimum 1345 revision must be active in the CPU to safely load that new microcode 1346 late into the running system. If disabled the check will not 1347 be enforced but the kernel will be tainted when the minimal 1348 revision check fails. 1349 1350 This minimal revision check can also be controlled via the 1351 "microcode.minrev" parameter on the kernel command line. 1352 1353 If unsure say Y. 1354 1355config X86_MSR 1356 tristate "/dev/cpu/*/msr - Model-specific register support" 1357 help 1358 This device gives privileged processes access to the x86 1359 Model-Specific Registers (MSRs). It is a character device with 1360 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1361 MSR accesses are directed to a specific CPU on multi-processor 1362 systems. 1363 1364config X86_CPUID 1365 tristate "/dev/cpu/*/cpuid - CPU information support" 1366 help 1367 This device gives processes access to the x86 CPUID instruction to 1368 be executed on a specific processor. It is a character device 1369 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1370 /dev/cpu/31/cpuid. 1371 1372choice 1373 prompt "High Memory Support" 1374 default HIGHMEM4G 1375 depends on X86_32 1376 1377config NOHIGHMEM 1378 bool "off" 1379 help 1380 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1381 However, the address space of 32-bit x86 processors is only 4 1382 Gigabytes large. That means that, if you have a large amount of 1383 physical memory, not all of it can be "permanently mapped" by the 1384 kernel. The physical memory that's not permanently mapped is called 1385 "high memory". 1386 1387 If you are compiling a kernel which will never run on a machine with 1388 more than 1 Gigabyte total physical RAM, answer "off" here (default 1389 choice and suitable for most users). This will result in a "3GB/1GB" 1390 split: 3GB are mapped so that each process sees a 3GB virtual memory 1391 space and the remaining part of the 4GB virtual memory space is used 1392 by the kernel to permanently map as much physical memory as 1393 possible. 1394 1395 If the machine has between 1 and 4 Gigabytes physical RAM, then 1396 answer "4GB" here. 1397 1398 If more than 4 Gigabytes is used then answer "64GB" here. This 1399 selection turns Intel PAE (Physical Address Extension) mode on. 1400 PAE implements 3-level paging on IA32 processors. PAE is fully 1401 supported by Linux, PAE mode is implemented on all recent Intel 1402 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1403 then the kernel will not boot on CPUs that don't support PAE! 1404 1405 The actual amount of total physical memory will either be 1406 auto detected or can be forced by using a kernel command line option 1407 such as "mem=256M". (Try "man bootparam" or see the documentation of 1408 your boot loader (lilo or loadlin) about how to pass options to the 1409 kernel at boot time.) 1410 1411 If unsure, say "off". 1412 1413config HIGHMEM4G 1414 bool "4GB" 1415 help 1416 Select this if you have a 32-bit processor and between 1 and 4 1417 gigabytes of physical RAM. 1418 1419config HIGHMEM64G 1420 bool "64GB" 1421 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1422 select X86_PAE 1423 help 1424 Select this if you have a 32-bit processor and more than 4 1425 gigabytes of physical RAM. 1426 1427endchoice 1428 1429choice 1430 prompt "Memory split" if EXPERT 1431 default VMSPLIT_3G 1432 depends on X86_32 1433 help 1434 Select the desired split between kernel and user memory. 1435 1436 If the address range available to the kernel is less than the 1437 physical memory installed, the remaining memory will be available 1438 as "high memory". Accessing high memory is a little more costly 1439 than low memory, as it needs to be mapped into the kernel first. 1440 Note that increasing the kernel address space limits the range 1441 available to user programs, making the address space there 1442 tighter. Selecting anything other than the default 3G/1G split 1443 will also likely make your kernel incompatible with binary-only 1444 kernel modules. 1445 1446 If you are not absolutely sure what you are doing, leave this 1447 option alone! 1448 1449 config VMSPLIT_3G 1450 bool "3G/1G user/kernel split" 1451 config VMSPLIT_3G_OPT 1452 depends on !X86_PAE 1453 bool "3G/1G user/kernel split (for full 1G low memory)" 1454 config VMSPLIT_2G 1455 bool "2G/2G user/kernel split" 1456 config VMSPLIT_2G_OPT 1457 depends on !X86_PAE 1458 bool "2G/2G user/kernel split (for full 2G low memory)" 1459 config VMSPLIT_1G 1460 bool "1G/3G user/kernel split" 1461endchoice 1462 1463config PAGE_OFFSET 1464 hex 1465 default 0xB0000000 if VMSPLIT_3G_OPT 1466 default 0x80000000 if VMSPLIT_2G 1467 default 0x78000000 if VMSPLIT_2G_OPT 1468 default 0x40000000 if VMSPLIT_1G 1469 default 0xC0000000 1470 depends on X86_32 1471 1472config HIGHMEM 1473 def_bool y 1474 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1475 1476config X86_PAE 1477 bool "PAE (Physical Address Extension) Support" 1478 depends on X86_32 && !HIGHMEM4G 1479 select PHYS_ADDR_T_64BIT 1480 select SWIOTLB 1481 help 1482 PAE is required for NX support, and furthermore enables 1483 larger swapspace support for non-overcommit purposes. It 1484 has the cost of more pagetable lookup overhead, and also 1485 consumes more pagetable space per process. 1486 1487config X86_5LEVEL 1488 bool "Enable 5-level page tables support" 1489 default y 1490 select DYNAMIC_MEMORY_LAYOUT 1491 select SPARSEMEM_VMEMMAP 1492 depends on X86_64 1493 help 1494 5-level paging enables access to larger address space: 1495 up to 128 PiB of virtual address space and 4 PiB of 1496 physical address space. 1497 1498 It will be supported by future Intel CPUs. 1499 1500 A kernel with the option enabled can be booted on machines that 1501 support 4- or 5-level paging. 1502 1503 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1504 information. 1505 1506 Say N if unsure. 1507 1508config X86_DIRECT_GBPAGES 1509 def_bool y 1510 depends on X86_64 1511 help 1512 Certain kernel features effectively disable kernel 1513 linear 1 GB mappings (even if the CPU otherwise 1514 supports them), so don't confuse the user by printing 1515 that we have them enabled. 1516 1517config X86_CPA_STATISTICS 1518 bool "Enable statistic for Change Page Attribute" 1519 depends on DEBUG_FS 1520 help 1521 Expose statistics about the Change Page Attribute mechanism, which 1522 helps to determine the effectiveness of preserving large and huge 1523 page mappings when mapping protections are changed. 1524 1525config X86_MEM_ENCRYPT 1526 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1527 select DYNAMIC_PHYSICAL_MASK 1528 def_bool n 1529 1530config AMD_MEM_ENCRYPT 1531 bool "AMD Secure Memory Encryption (SME) support" 1532 depends on X86_64 && CPU_SUP_AMD 1533 depends on EFI_STUB 1534 select DMA_COHERENT_POOL 1535 select ARCH_USE_MEMREMAP_PROT 1536 select INSTRUCTION_DECODER 1537 select ARCH_HAS_CC_PLATFORM 1538 select X86_MEM_ENCRYPT 1539 select UNACCEPTED_MEMORY 1540 help 1541 Say yes to enable support for the encryption of system memory. 1542 This requires an AMD processor that supports Secure Memory 1543 Encryption (SME). 1544 1545# Common NUMA Features 1546config NUMA 1547 bool "NUMA Memory Allocation and Scheduler Support" 1548 depends on SMP 1549 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1550 default y if X86_BIGSMP 1551 select USE_PERCPU_NUMA_NODE_ID 1552 help 1553 Enable NUMA (Non-Uniform Memory Access) support. 1554 1555 The kernel will try to allocate memory used by a CPU on the 1556 local memory controller of the CPU and add some more 1557 NUMA awareness to the kernel. 1558 1559 For 64-bit this is recommended if the system is Intel Core i7 1560 (or later), AMD Opteron, or EM64T NUMA. 1561 1562 For 32-bit this is only needed if you boot a 32-bit 1563 kernel on a 64-bit NUMA platform. 1564 1565 Otherwise, you should say N. 1566 1567config AMD_NUMA 1568 def_bool y 1569 prompt "Old style AMD Opteron NUMA detection" 1570 depends on X86_64 && NUMA && PCI 1571 help 1572 Enable AMD NUMA node topology detection. You should say Y here if 1573 you have a multi processor AMD system. This uses an old method to 1574 read the NUMA configuration directly from the builtin Northbridge 1575 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1576 which also takes priority if both are compiled in. 1577 1578config X86_64_ACPI_NUMA 1579 def_bool y 1580 prompt "ACPI NUMA detection" 1581 depends on X86_64 && NUMA && ACPI && PCI 1582 select ACPI_NUMA 1583 help 1584 Enable ACPI SRAT based node topology detection. 1585 1586config NUMA_EMU 1587 bool "NUMA emulation" 1588 depends on NUMA 1589 help 1590 Enable NUMA emulation. A flat machine will be split 1591 into virtual nodes when booted with "numa=fake=N", where N is the 1592 number of nodes. This is only useful for debugging. 1593 1594config NODES_SHIFT 1595 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1596 range 1 10 1597 default "10" if MAXSMP 1598 default "6" if X86_64 1599 default "3" 1600 depends on NUMA 1601 help 1602 Specify the maximum number of NUMA Nodes available on the target 1603 system. Increases memory reserved to accommodate various tables. 1604 1605config ARCH_FLATMEM_ENABLE 1606 def_bool y 1607 depends on X86_32 && !NUMA 1608 1609config ARCH_SPARSEMEM_ENABLE 1610 def_bool y 1611 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1612 select SPARSEMEM_STATIC if X86_32 1613 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1614 1615config ARCH_SPARSEMEM_DEFAULT 1616 def_bool X86_64 || (NUMA && X86_32) 1617 1618config ARCH_SELECT_MEMORY_MODEL 1619 def_bool y 1620 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1621 1622config ARCH_MEMORY_PROBE 1623 bool "Enable sysfs memory/probe interface" 1624 depends on MEMORY_HOTPLUG 1625 help 1626 This option enables a sysfs memory/probe interface for testing. 1627 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1628 If you are unsure how to answer this question, answer N. 1629 1630config ARCH_PROC_KCORE_TEXT 1631 def_bool y 1632 depends on X86_64 && PROC_KCORE 1633 1634config ILLEGAL_POINTER_VALUE 1635 hex 1636 default 0 if X86_32 1637 default 0xdead000000000000 if X86_64 1638 1639config X86_PMEM_LEGACY_DEVICE 1640 bool 1641 1642config X86_PMEM_LEGACY 1643 tristate "Support non-standard NVDIMMs and ADR protected memory" 1644 depends on PHYS_ADDR_T_64BIT 1645 depends on BLK_DEV 1646 select X86_PMEM_LEGACY_DEVICE 1647 select NUMA_KEEP_MEMINFO if NUMA 1648 select LIBNVDIMM 1649 help 1650 Treat memory marked using the non-standard e820 type of 12 as used 1651 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1652 The kernel will offer these regions to the 'pmem' driver so 1653 they can be used for persistent storage. 1654 1655 Say Y if unsure. 1656 1657config HIGHPTE 1658 bool "Allocate 3rd-level pagetables from highmem" 1659 depends on HIGHMEM 1660 help 1661 The VM uses one page table entry for each page of physical memory. 1662 For systems with a lot of RAM, this can be wasteful of precious 1663 low memory. Setting this option will put user-space page table 1664 entries in high memory. 1665 1666config X86_CHECK_BIOS_CORRUPTION 1667 bool "Check for low memory corruption" 1668 help 1669 Periodically check for memory corruption in low memory, which 1670 is suspected to be caused by BIOS. Even when enabled in the 1671 configuration, it is disabled at runtime. Enable it by 1672 setting "memory_corruption_check=1" on the kernel command 1673 line. By default it scans the low 64k of memory every 60 1674 seconds; see the memory_corruption_check_size and 1675 memory_corruption_check_period parameters in 1676 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1677 1678 When enabled with the default parameters, this option has 1679 almost no overhead, as it reserves a relatively small amount 1680 of memory and scans it infrequently. It both detects corruption 1681 and prevents it from affecting the running system. 1682 1683 It is, however, intended as a diagnostic tool; if repeatable 1684 BIOS-originated corruption always affects the same memory, 1685 you can use memmap= to prevent the kernel from using that 1686 memory. 1687 1688config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1689 bool "Set the default setting of memory_corruption_check" 1690 depends on X86_CHECK_BIOS_CORRUPTION 1691 default y 1692 help 1693 Set whether the default state of memory_corruption_check is 1694 on or off. 1695 1696config MATH_EMULATION 1697 bool 1698 depends on MODIFY_LDT_SYSCALL 1699 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1700 help 1701 Linux can emulate a math coprocessor (used for floating point 1702 operations) if you don't have one. 486DX and Pentium processors have 1703 a math coprocessor built in, 486SX and 386 do not, unless you added 1704 a 487DX or 387, respectively. (The messages during boot time can 1705 give you some hints here ["man dmesg"].) Everyone needs either a 1706 coprocessor or this emulation. 1707 1708 If you don't have a math coprocessor, you need to say Y here; if you 1709 say Y here even though you have a coprocessor, the coprocessor will 1710 be used nevertheless. (This behavior can be changed with the kernel 1711 command line option "no387", which comes handy if your coprocessor 1712 is broken. Try "man bootparam" or see the documentation of your boot 1713 loader (lilo or loadlin) about how to pass options to the kernel at 1714 boot time.) This means that it is a good idea to say Y here if you 1715 intend to use this kernel on different machines. 1716 1717 More information about the internals of the Linux math coprocessor 1718 emulation can be found in <file:arch/x86/math-emu/README>. 1719 1720 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1721 kernel, it won't hurt. 1722 1723config MTRR 1724 def_bool y 1725 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1726 help 1727 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1728 the Memory Type Range Registers (MTRRs) may be used to control 1729 processor access to memory ranges. This is most useful if you have 1730 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1731 allows bus write transfers to be combined into a larger transfer 1732 before bursting over the PCI/AGP bus. This can increase performance 1733 of image write operations 2.5 times or more. Saying Y here creates a 1734 /proc/mtrr file which may be used to manipulate your processor's 1735 MTRRs. Typically the X server should use this. 1736 1737 This code has a reasonably generic interface so that similar 1738 control registers on other processors can be easily supported 1739 as well: 1740 1741 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1742 Registers (ARRs) which provide a similar functionality to MTRRs. For 1743 these, the ARRs are used to emulate the MTRRs. 1744 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1745 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1746 write-combining. All of these processors are supported by this code 1747 and it makes sense to say Y here if you have one of them. 1748 1749 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1750 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1751 can lead to all sorts of problems, so it's good to say Y here. 1752 1753 You can safely say Y even if your machine doesn't have MTRRs, you'll 1754 just add about 9 KB to your kernel. 1755 1756 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1757 1758config MTRR_SANITIZER 1759 def_bool y 1760 prompt "MTRR cleanup support" 1761 depends on MTRR 1762 help 1763 Convert MTRR layout from continuous to discrete, so X drivers can 1764 add writeback entries. 1765 1766 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1767 The largest mtrr entry size for a continuous block can be set with 1768 mtrr_chunk_size. 1769 1770 If unsure, say Y. 1771 1772config MTRR_SANITIZER_ENABLE_DEFAULT 1773 int "MTRR cleanup enable value (0-1)" 1774 range 0 1 1775 default "0" 1776 depends on MTRR_SANITIZER 1777 help 1778 Enable mtrr cleanup default value 1779 1780config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1781 int "MTRR cleanup spare reg num (0-7)" 1782 range 0 7 1783 default "1" 1784 depends on MTRR_SANITIZER 1785 help 1786 mtrr cleanup spare entries default, it can be changed via 1787 mtrr_spare_reg_nr=N on the kernel command line. 1788 1789config X86_PAT 1790 def_bool y 1791 prompt "x86 PAT support" if EXPERT 1792 depends on MTRR 1793 help 1794 Use PAT attributes to setup page level cache control. 1795 1796 PATs are the modern equivalents of MTRRs and are much more 1797 flexible than MTRRs. 1798 1799 Say N here if you see bootup problems (boot crash, boot hang, 1800 spontaneous reboots) or a non-working video driver. 1801 1802 If unsure, say Y. 1803 1804config ARCH_USES_PG_UNCACHED 1805 def_bool y 1806 depends on X86_PAT 1807 1808config X86_UMIP 1809 def_bool y 1810 prompt "User Mode Instruction Prevention" if EXPERT 1811 help 1812 User Mode Instruction Prevention (UMIP) is a security feature in 1813 some x86 processors. If enabled, a general protection fault is 1814 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1815 executed in user mode. These instructions unnecessarily expose 1816 information about the hardware state. 1817 1818 The vast majority of applications do not use these instructions. 1819 For the very few that do, software emulation is provided in 1820 specific cases in protected and virtual-8086 modes. Emulated 1821 results are dummy. 1822 1823config CC_HAS_IBT 1824 # GCC >= 9 and binutils >= 2.29 1825 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1826 # Clang/LLVM >= 14 1827 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1828 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1829 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1830 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1831 $(as-instr,endbr64) 1832 1833config X86_CET 1834 def_bool n 1835 help 1836 CET features configured (Shadow stack or IBT) 1837 1838config X86_KERNEL_IBT 1839 prompt "Indirect Branch Tracking" 1840 def_bool y 1841 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1842 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1843 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1844 select OBJTOOL 1845 select X86_CET 1846 help 1847 Build the kernel with support for Indirect Branch Tracking, a 1848 hardware support course-grain forward-edge Control Flow Integrity 1849 protection. It enforces that all indirect calls must land on 1850 an ENDBR instruction, as such, the compiler will instrument the 1851 code with them to make this happen. 1852 1853 In addition to building the kernel with IBT, seal all functions that 1854 are not indirect call targets, avoiding them ever becoming one. 1855 1856 This requires LTO like objtool runs and will slow down the build. It 1857 does significantly reduce the number of ENDBR instructions in the 1858 kernel image. 1859 1860config X86_INTEL_MEMORY_PROTECTION_KEYS 1861 prompt "Memory Protection Keys" 1862 def_bool y 1863 # Note: only available in 64-bit mode 1864 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1865 select ARCH_USES_HIGH_VMA_FLAGS 1866 select ARCH_HAS_PKEYS 1867 help 1868 Memory Protection Keys provides a mechanism for enforcing 1869 page-based protections, but without requiring modification of the 1870 page tables when an application changes protection domains. 1871 1872 For details, see Documentation/core-api/protection-keys.rst 1873 1874 If unsure, say y. 1875 1876choice 1877 prompt "TSX enable mode" 1878 depends on CPU_SUP_INTEL 1879 default X86_INTEL_TSX_MODE_OFF 1880 help 1881 Intel's TSX (Transactional Synchronization Extensions) feature 1882 allows to optimize locking protocols through lock elision which 1883 can lead to a noticeable performance boost. 1884 1885 On the other hand it has been shown that TSX can be exploited 1886 to form side channel attacks (e.g. TAA) and chances are there 1887 will be more of those attacks discovered in the future. 1888 1889 Therefore TSX is not enabled by default (aka tsx=off). An admin 1890 might override this decision by tsx=on the command line parameter. 1891 Even with TSX enabled, the kernel will attempt to enable the best 1892 possible TAA mitigation setting depending on the microcode available 1893 for the particular machine. 1894 1895 This option allows to set the default tsx mode between tsx=on, =off 1896 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1897 details. 1898 1899 Say off if not sure, auto if TSX is in use but it should be used on safe 1900 platforms or on if TSX is in use and the security aspect of tsx is not 1901 relevant. 1902 1903config X86_INTEL_TSX_MODE_OFF 1904 bool "off" 1905 help 1906 TSX is disabled if possible - equals to tsx=off command line parameter. 1907 1908config X86_INTEL_TSX_MODE_ON 1909 bool "on" 1910 help 1911 TSX is always enabled on TSX capable HW - equals the tsx=on command 1912 line parameter. 1913 1914config X86_INTEL_TSX_MODE_AUTO 1915 bool "auto" 1916 help 1917 TSX is enabled on TSX capable HW that is believed to be safe against 1918 side channel attacks- equals the tsx=auto command line parameter. 1919endchoice 1920 1921config X86_SGX 1922 bool "Software Guard eXtensions (SGX)" 1923 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1924 depends on CRYPTO=y 1925 depends on CRYPTO_SHA256=y 1926 select MMU_NOTIFIER 1927 select NUMA_KEEP_MEMINFO if NUMA 1928 select XARRAY_MULTI 1929 help 1930 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1931 that can be used by applications to set aside private regions of code 1932 and data, referred to as enclaves. An enclave's private memory can 1933 only be accessed by code running within the enclave. Accesses from 1934 outside the enclave, including other enclaves, are disallowed by 1935 hardware. 1936 1937 If unsure, say N. 1938 1939config X86_USER_SHADOW_STACK 1940 bool "X86 userspace shadow stack" 1941 depends on AS_WRUSS 1942 depends on X86_64 1943 select ARCH_USES_HIGH_VMA_FLAGS 1944 select X86_CET 1945 help 1946 Shadow stack protection is a hardware feature that detects function 1947 return address corruption. This helps mitigate ROP attacks. 1948 Applications must be enabled to use it, and old userspace does not 1949 get protection "for free". 1950 1951 CPUs supporting shadow stacks were first released in 2020. 1952 1953 See Documentation/arch/x86/shstk.rst for more information. 1954 1955 If unsure, say N. 1956 1957config EFI 1958 bool "EFI runtime service support" 1959 depends on ACPI 1960 select UCS2_STRING 1961 select EFI_RUNTIME_WRAPPERS 1962 select ARCH_USE_MEMREMAP_PROT 1963 select EFI_RUNTIME_MAP if KEXEC_CORE 1964 help 1965 This enables the kernel to use EFI runtime services that are 1966 available (such as the EFI variable services). 1967 1968 This option is only useful on systems that have EFI firmware. 1969 In addition, you should use the latest ELILO loader available 1970 at <http://elilo.sourceforge.net> in order to take advantage 1971 of EFI runtime services. However, even with this option, the 1972 resultant kernel should continue to boot on existing non-EFI 1973 platforms. 1974 1975config EFI_STUB 1976 bool "EFI stub support" 1977 depends on EFI 1978 select RELOCATABLE 1979 help 1980 This kernel feature allows a bzImage to be loaded directly 1981 by EFI firmware without the use of a bootloader. 1982 1983 See Documentation/admin-guide/efi-stub.rst for more information. 1984 1985config EFI_HANDOVER_PROTOCOL 1986 bool "EFI handover protocol (DEPRECATED)" 1987 depends on EFI_STUB 1988 default y 1989 help 1990 Select this in order to include support for the deprecated EFI 1991 handover protocol, which defines alternative entry points into the 1992 EFI stub. This is a practice that has no basis in the UEFI 1993 specification, and requires a priori knowledge on the part of the 1994 bootloader about Linux/x86 specific ways of passing the command line 1995 and initrd, and where in memory those assets may be loaded. 1996 1997 If in doubt, say Y. Even though the corresponding support is not 1998 present in upstream GRUB or other bootloaders, most distros build 1999 GRUB with numerous downstream patches applied, and may rely on the 2000 handover protocol as as result. 2001 2002config EFI_MIXED 2003 bool "EFI mixed-mode support" 2004 depends on EFI_STUB && X86_64 2005 help 2006 Enabling this feature allows a 64-bit kernel to be booted 2007 on a 32-bit firmware, provided that your CPU supports 64-bit 2008 mode. 2009 2010 Note that it is not possible to boot a mixed-mode enabled 2011 kernel via the EFI boot stub - a bootloader that supports 2012 the EFI handover protocol must be used. 2013 2014 If unsure, say N. 2015 2016config EFI_FAKE_MEMMAP 2017 bool "Enable EFI fake memory map" 2018 depends on EFI 2019 help 2020 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2021 this parameter, you can add arbitrary attribute to specific memory 2022 range by updating original (firmware provided) EFI memmap. This is 2023 useful for debugging of EFI memmap related feature, e.g., Address 2024 Range Mirroring feature. 2025 2026config EFI_MAX_FAKE_MEM 2027 int "maximum allowable number of ranges in efi_fake_mem boot option" 2028 depends on EFI_FAKE_MEMMAP 2029 range 1 128 2030 default 8 2031 help 2032 Maximum allowable number of ranges in efi_fake_mem boot option. 2033 Ranges can be set up to this value using comma-separated list. 2034 The default value is 8. 2035 2036config EFI_RUNTIME_MAP 2037 bool "Export EFI runtime maps to sysfs" if EXPERT 2038 depends on EFI 2039 help 2040 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2041 That memory map is required by the 2nd kernel to set up EFI virtual 2042 mappings after kexec, but can also be used for debugging purposes. 2043 2044 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2045 2046source "kernel/Kconfig.hz" 2047 2048config ARCH_SUPPORTS_KEXEC 2049 def_bool y 2050 2051config ARCH_SUPPORTS_KEXEC_FILE 2052 def_bool X86_64 2053 2054config ARCH_SELECTS_KEXEC_FILE 2055 def_bool y 2056 depends on KEXEC_FILE 2057 select HAVE_IMA_KEXEC if IMA 2058 2059config ARCH_SUPPORTS_KEXEC_PURGATORY 2060 def_bool y 2061 2062config ARCH_SUPPORTS_KEXEC_SIG 2063 def_bool y 2064 2065config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2066 def_bool y 2067 2068config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2069 def_bool y 2070 2071config ARCH_SUPPORTS_KEXEC_JUMP 2072 def_bool y 2073 2074config ARCH_SUPPORTS_CRASH_DUMP 2075 def_bool X86_64 || (X86_32 && HIGHMEM) 2076 2077config ARCH_SUPPORTS_CRASH_HOTPLUG 2078 def_bool y 2079 2080config PHYSICAL_START 2081 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2082 default "0x1000000" 2083 help 2084 This gives the physical address where the kernel is loaded. 2085 2086 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2087 bzImage will decompress itself to above physical address and 2088 run from there. Otherwise, bzImage will run from the address where 2089 it has been loaded by the boot loader and will ignore above physical 2090 address. 2091 2092 In normal kdump cases one does not have to set/change this option 2093 as now bzImage can be compiled as a completely relocatable image 2094 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2095 address. This option is mainly useful for the folks who don't want 2096 to use a bzImage for capturing the crash dump and want to use a 2097 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2098 to be specifically compiled to run from a specific memory area 2099 (normally a reserved region) and this option comes handy. 2100 2101 So if you are using bzImage for capturing the crash dump, 2102 leave the value here unchanged to 0x1000000 and set 2103 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2104 for capturing the crash dump change this value to start of 2105 the reserved region. In other words, it can be set based on 2106 the "X" value as specified in the "crashkernel=YM@XM" 2107 command line boot parameter passed to the panic-ed 2108 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2109 for more details about crash dumps. 2110 2111 Usage of bzImage for capturing the crash dump is recommended as 2112 one does not have to build two kernels. Same kernel can be used 2113 as production kernel and capture kernel. Above option should have 2114 gone away after relocatable bzImage support is introduced. But it 2115 is present because there are users out there who continue to use 2116 vmlinux for dump capture. This option should go away down the 2117 line. 2118 2119 Don't change this unless you know what you are doing. 2120 2121config RELOCATABLE 2122 bool "Build a relocatable kernel" 2123 default y 2124 help 2125 This builds a kernel image that retains relocation information 2126 so it can be loaded someplace besides the default 1MB. 2127 The relocations tend to make the kernel binary about 10% larger, 2128 but are discarded at runtime. 2129 2130 One use is for the kexec on panic case where the recovery kernel 2131 must live at a different physical address than the primary 2132 kernel. 2133 2134 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2135 it has been loaded at and the compile time physical address 2136 (CONFIG_PHYSICAL_START) is used as the minimum location. 2137 2138config RANDOMIZE_BASE 2139 bool "Randomize the address of the kernel image (KASLR)" 2140 depends on RELOCATABLE 2141 default y 2142 help 2143 In support of Kernel Address Space Layout Randomization (KASLR), 2144 this randomizes the physical address at which the kernel image 2145 is decompressed and the virtual address where the kernel 2146 image is mapped, as a security feature that deters exploit 2147 attempts relying on knowledge of the location of kernel 2148 code internals. 2149 2150 On 64-bit, the kernel physical and virtual addresses are 2151 randomized separately. The physical address will be anywhere 2152 between 16MB and the top of physical memory (up to 64TB). The 2153 virtual address will be randomized from 16MB up to 1GB (9 bits 2154 of entropy). Note that this also reduces the memory space 2155 available to kernel modules from 1.5GB to 1GB. 2156 2157 On 32-bit, the kernel physical and virtual addresses are 2158 randomized together. They will be randomized from 16MB up to 2159 512MB (8 bits of entropy). 2160 2161 Entropy is generated using the RDRAND instruction if it is 2162 supported. If RDTSC is supported, its value is mixed into 2163 the entropy pool as well. If neither RDRAND nor RDTSC are 2164 supported, then entropy is read from the i8254 timer. The 2165 usable entropy is limited by the kernel being built using 2166 2GB addressing, and that PHYSICAL_ALIGN must be at a 2167 minimum of 2MB. As a result, only 10 bits of entropy are 2168 theoretically possible, but the implementations are further 2169 limited due to memory layouts. 2170 2171 If unsure, say Y. 2172 2173# Relocation on x86 needs some additional build support 2174config X86_NEED_RELOCS 2175 def_bool y 2176 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2177 2178config PHYSICAL_ALIGN 2179 hex "Alignment value to which kernel should be aligned" 2180 default "0x200000" 2181 range 0x2000 0x1000000 if X86_32 2182 range 0x200000 0x1000000 if X86_64 2183 help 2184 This value puts the alignment restrictions on physical address 2185 where kernel is loaded and run from. Kernel is compiled for an 2186 address which meets above alignment restriction. 2187 2188 If bootloader loads the kernel at a non-aligned address and 2189 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2190 address aligned to above value and run from there. 2191 2192 If bootloader loads the kernel at a non-aligned address and 2193 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2194 load address and decompress itself to the address it has been 2195 compiled for and run from there. The address for which kernel is 2196 compiled already meets above alignment restrictions. Hence the 2197 end result is that kernel runs from a physical address meeting 2198 above alignment restrictions. 2199 2200 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2201 this value must be a multiple of 0x200000. 2202 2203 Don't change this unless you know what you are doing. 2204 2205config DYNAMIC_MEMORY_LAYOUT 2206 bool 2207 help 2208 This option makes base addresses of vmalloc and vmemmap as well as 2209 __PAGE_OFFSET movable during boot. 2210 2211config RANDOMIZE_MEMORY 2212 bool "Randomize the kernel memory sections" 2213 depends on X86_64 2214 depends on RANDOMIZE_BASE 2215 select DYNAMIC_MEMORY_LAYOUT 2216 default RANDOMIZE_BASE 2217 help 2218 Randomizes the base virtual address of kernel memory sections 2219 (physical memory mapping, vmalloc & vmemmap). This security feature 2220 makes exploits relying on predictable memory locations less reliable. 2221 2222 The order of allocations remains unchanged. Entropy is generated in 2223 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2224 configuration have in average 30,000 different possible virtual 2225 addresses for each memory section. 2226 2227 If unsure, say Y. 2228 2229config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2230 hex "Physical memory mapping padding" if EXPERT 2231 depends on RANDOMIZE_MEMORY 2232 default "0xa" if MEMORY_HOTPLUG 2233 default "0x0" 2234 range 0x1 0x40 if MEMORY_HOTPLUG 2235 range 0x0 0x40 2236 help 2237 Define the padding in terabytes added to the existing physical 2238 memory size during kernel memory randomization. It is useful 2239 for memory hotplug support but reduces the entropy available for 2240 address randomization. 2241 2242 If unsure, leave at the default value. 2243 2244config ADDRESS_MASKING 2245 bool "Linear Address Masking support" 2246 depends on X86_64 2247 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2248 help 2249 Linear Address Masking (LAM) modifies the checking that is applied 2250 to 64-bit linear addresses, allowing software to use of the 2251 untranslated address bits for metadata. 2252 2253 The capability can be used for efficient address sanitizers (ASAN) 2254 implementation and for optimizations in JITs. 2255 2256config HOTPLUG_CPU 2257 def_bool y 2258 depends on SMP 2259 2260config COMPAT_VDSO 2261 def_bool n 2262 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2263 depends on COMPAT_32 2264 help 2265 Certain buggy versions of glibc will crash if they are 2266 presented with a 32-bit vDSO that is not mapped at the address 2267 indicated in its segment table. 2268 2269 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2270 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2271 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2272 the only released version with the bug, but OpenSUSE 9 2273 contains a buggy "glibc 2.3.2". 2274 2275 The symptom of the bug is that everything crashes on startup, saying: 2276 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2277 2278 Saying Y here changes the default value of the vdso32 boot 2279 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2280 This works around the glibc bug but hurts performance. 2281 2282 If unsure, say N: if you are compiling your own kernel, you 2283 are unlikely to be using a buggy version of glibc. 2284 2285choice 2286 prompt "vsyscall table for legacy applications" 2287 depends on X86_64 2288 default LEGACY_VSYSCALL_XONLY 2289 help 2290 Legacy user code that does not know how to find the vDSO expects 2291 to be able to issue three syscalls by calling fixed addresses in 2292 kernel space. Since this location is not randomized with ASLR, 2293 it can be used to assist security vulnerability exploitation. 2294 2295 This setting can be changed at boot time via the kernel command 2296 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2297 is deprecated and can only be enabled using the kernel command 2298 line. 2299 2300 On a system with recent enough glibc (2.14 or newer) and no 2301 static binaries, you can say None without a performance penalty 2302 to improve security. 2303 2304 If unsure, select "Emulate execution only". 2305 2306 config LEGACY_VSYSCALL_XONLY 2307 bool "Emulate execution only" 2308 help 2309 The kernel traps and emulates calls into the fixed vsyscall 2310 address mapping and does not allow reads. This 2311 configuration is recommended when userspace might use the 2312 legacy vsyscall area but support for legacy binary 2313 instrumentation of legacy code is not needed. It mitigates 2314 certain uses of the vsyscall area as an ASLR-bypassing 2315 buffer. 2316 2317 config LEGACY_VSYSCALL_NONE 2318 bool "None" 2319 help 2320 There will be no vsyscall mapping at all. This will 2321 eliminate any risk of ASLR bypass due to the vsyscall 2322 fixed address mapping. Attempts to use the vsyscalls 2323 will be reported to dmesg, so that either old or 2324 malicious userspace programs can be identified. 2325 2326endchoice 2327 2328config CMDLINE_BOOL 2329 bool "Built-in kernel command line" 2330 help 2331 Allow for specifying boot arguments to the kernel at 2332 build time. On some systems (e.g. embedded ones), it is 2333 necessary or convenient to provide some or all of the 2334 kernel boot arguments with the kernel itself (that is, 2335 to not rely on the boot loader to provide them.) 2336 2337 To compile command line arguments into the kernel, 2338 set this option to 'Y', then fill in the 2339 boot arguments in CONFIG_CMDLINE. 2340 2341 Systems with fully functional boot loaders (i.e. non-embedded) 2342 should leave this option set to 'N'. 2343 2344config CMDLINE 2345 string "Built-in kernel command string" 2346 depends on CMDLINE_BOOL 2347 default "" 2348 help 2349 Enter arguments here that should be compiled into the kernel 2350 image and used at boot time. If the boot loader provides a 2351 command line at boot time, it is appended to this string to 2352 form the full kernel command line, when the system boots. 2353 2354 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2355 change this behavior. 2356 2357 In most cases, the command line (whether built-in or provided 2358 by the boot loader) should specify the device for the root 2359 file system. 2360 2361config CMDLINE_OVERRIDE 2362 bool "Built-in command line overrides boot loader arguments" 2363 depends on CMDLINE_BOOL && CMDLINE != "" 2364 help 2365 Set this option to 'Y' to have the kernel ignore the boot loader 2366 command line, and use ONLY the built-in command line. 2367 2368 This is used to work around broken boot loaders. This should 2369 be set to 'N' under normal conditions. 2370 2371config MODIFY_LDT_SYSCALL 2372 bool "Enable the LDT (local descriptor table)" if EXPERT 2373 default y 2374 help 2375 Linux can allow user programs to install a per-process x86 2376 Local Descriptor Table (LDT) using the modify_ldt(2) system 2377 call. This is required to run 16-bit or segmented code such as 2378 DOSEMU or some Wine programs. It is also used by some very old 2379 threading libraries. 2380 2381 Enabling this feature adds a small amount of overhead to 2382 context switches and increases the low-level kernel attack 2383 surface. Disabling it removes the modify_ldt(2) system call. 2384 2385 Saying 'N' here may make sense for embedded or server kernels. 2386 2387config STRICT_SIGALTSTACK_SIZE 2388 bool "Enforce strict size checking for sigaltstack" 2389 depends on DYNAMIC_SIGFRAME 2390 help 2391 For historical reasons MINSIGSTKSZ is a constant which became 2392 already too small with AVX512 support. Add a mechanism to 2393 enforce strict checking of the sigaltstack size against the 2394 real size of the FPU frame. This option enables the check 2395 by default. It can also be controlled via the kernel command 2396 line option 'strict_sas_size' independent of this config 2397 switch. Enabling it might break existing applications which 2398 allocate a too small sigaltstack but 'work' because they 2399 never get a signal delivered. 2400 2401 Say 'N' unless you want to really enforce this check. 2402 2403source "kernel/livepatch/Kconfig" 2404 2405endmenu 2406 2407config CC_HAS_SLS 2408 def_bool $(cc-option,-mharden-sls=all) 2409 2410config CC_HAS_RETURN_THUNK 2411 def_bool $(cc-option,-mfunction-return=thunk-extern) 2412 2413config CC_HAS_ENTRY_PADDING 2414 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2415 2416config FUNCTION_PADDING_CFI 2417 int 2418 default 59 if FUNCTION_ALIGNMENT_64B 2419 default 27 if FUNCTION_ALIGNMENT_32B 2420 default 11 if FUNCTION_ALIGNMENT_16B 2421 default 3 if FUNCTION_ALIGNMENT_8B 2422 default 0 2423 2424# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2425# except Kconfig can't do arithmetic :/ 2426config FUNCTION_PADDING_BYTES 2427 int 2428 default FUNCTION_PADDING_CFI if CFI_CLANG 2429 default FUNCTION_ALIGNMENT 2430 2431config CALL_PADDING 2432 def_bool n 2433 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2434 select FUNCTION_ALIGNMENT_16B 2435 2436config FINEIBT 2437 def_bool y 2438 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE 2439 select CALL_PADDING 2440 2441config HAVE_CALL_THUNKS 2442 def_bool y 2443 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL 2444 2445config CALL_THUNKS 2446 def_bool n 2447 select CALL_PADDING 2448 2449config PREFIX_SYMBOLS 2450 def_bool y 2451 depends on CALL_PADDING && !CFI_CLANG 2452 2453menuconfig CPU_MITIGATIONS 2454 bool "Mitigations for CPU vulnerabilities" 2455 default y 2456 help 2457 Say Y here to enable options which enable mitigations for hardware 2458 vulnerabilities (usually related to speculative execution). 2459 Mitigations can be disabled or restricted to SMT systems at runtime 2460 via the "mitigations" kernel parameter. 2461 2462 If you say N, all mitigations will be disabled. This CANNOT be 2463 overridden at runtime. 2464 2465 Say 'Y', unless you really know what you are doing. 2466 2467if CPU_MITIGATIONS 2468 2469config PAGE_TABLE_ISOLATION 2470 bool "Remove the kernel mapping in user mode" 2471 default y 2472 depends on (X86_64 || X86_PAE) 2473 help 2474 This feature reduces the number of hardware side channels by 2475 ensuring that the majority of kernel addresses are not mapped 2476 into userspace. 2477 2478 See Documentation/arch/x86/pti.rst for more details. 2479 2480config RETPOLINE 2481 bool "Avoid speculative indirect branches in kernel" 2482 select OBJTOOL if HAVE_OBJTOOL 2483 default y 2484 help 2485 Compile kernel with the retpoline compiler options to guard against 2486 kernel-to-user data leaks by avoiding speculative indirect 2487 branches. Requires a compiler with -mindirect-branch=thunk-extern 2488 support for full protection. The kernel may run slower. 2489 2490config RETHUNK 2491 bool "Enable return-thunks" 2492 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2493 select OBJTOOL if HAVE_OBJTOOL 2494 default y if X86_64 2495 help 2496 Compile the kernel with the return-thunks compiler option to guard 2497 against kernel-to-user data leaks by avoiding return speculation. 2498 Requires a compiler with -mfunction-return=thunk-extern 2499 support for full protection. The kernel may run slower. 2500 2501config CPU_UNRET_ENTRY 2502 bool "Enable UNRET on kernel entry" 2503 depends on CPU_SUP_AMD && RETHUNK && X86_64 2504 default y 2505 help 2506 Compile the kernel with support for the retbleed=unret mitigation. 2507 2508config CALL_DEPTH_TRACKING 2509 bool "Mitigate RSB underflow with call depth tracking" 2510 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2511 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2512 select CALL_THUNKS 2513 default y 2514 help 2515 Compile the kernel with call depth tracking to mitigate the Intel 2516 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2517 mitigation is off by default and needs to be enabled on the 2518 kernel command line via the retbleed=stuff option. For 2519 non-affected systems the overhead of this option is marginal as 2520 the call depth tracking is using run-time generated call thunks 2521 in a compiler generated padding area and call patching. This 2522 increases text size by ~5%. For non affected systems this space 2523 is unused. On affected SKL systems this results in a significant 2524 performance gain over the IBRS mitigation. 2525 2526config CALL_THUNKS_DEBUG 2527 bool "Enable call thunks and call depth tracking debugging" 2528 depends on CALL_DEPTH_TRACKING 2529 select FUNCTION_ALIGNMENT_32B 2530 default n 2531 help 2532 Enable call/ret counters for imbalance detection and build in 2533 a noisy dmesg about callthunks generation and call patching for 2534 trouble shooting. The debug prints need to be enabled on the 2535 kernel command line with 'debug-callthunks'. 2536 Only enable this when you are debugging call thunks as this 2537 creates a noticeable runtime overhead. If unsure say N. 2538 2539config CPU_IBPB_ENTRY 2540 bool "Enable IBPB on kernel entry" 2541 depends on CPU_SUP_AMD && X86_64 2542 default y 2543 help 2544 Compile the kernel with support for the retbleed=ibpb and 2545 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations. 2546 2547config CPU_IBRS_ENTRY 2548 bool "Enable IBRS on kernel entry" 2549 depends on CPU_SUP_INTEL && X86_64 2550 default y 2551 help 2552 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2553 This mitigates both spectre_v2 and retbleed at great cost to 2554 performance. 2555 2556config CPU_SRSO 2557 bool "Mitigate speculative RAS overflow on AMD" 2558 depends on CPU_SUP_AMD && X86_64 && RETHUNK 2559 default y 2560 help 2561 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2562 2563config SLS 2564 bool "Mitigate Straight-Line-Speculation" 2565 depends on CC_HAS_SLS && X86_64 2566 select OBJTOOL if HAVE_OBJTOOL 2567 default n 2568 help 2569 Compile the kernel with straight-line-speculation options to guard 2570 against straight line speculation. The kernel image might be slightly 2571 larger. 2572 2573config GDS_FORCE_MITIGATION 2574 bool "Force GDS Mitigation" 2575 depends on CPU_SUP_INTEL 2576 default n 2577 help 2578 Gather Data Sampling (GDS) is a hardware vulnerability which allows 2579 unprivileged speculative access to data which was previously stored in 2580 vector registers. 2581 2582 This option is equivalent to setting gather_data_sampling=force on the 2583 command line. The microcode mitigation is used if present, otherwise 2584 AVX is disabled as a mitigation. On affected systems that are missing 2585 the microcode any userspace code that unconditionally uses AVX will 2586 break with this option set. 2587 2588 Setting this option on systems not vulnerable to GDS has no effect. 2589 2590 If in doubt, say N. 2591 2592config MITIGATION_RFDS 2593 bool "RFDS Mitigation" 2594 depends on CPU_SUP_INTEL 2595 default y 2596 help 2597 Enable mitigation for Register File Data Sampling (RFDS) by default. 2598 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2599 allows unprivileged speculative access to stale data previously 2600 stored in floating point, vector and integer registers. 2601 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2602 2603config MITIGATION_SPECTRE_BHI 2604 bool "Mitigate Spectre-BHB (Branch History Injection)" 2605 depends on CPU_SUP_INTEL 2606 default y 2607 help 2608 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2609 where the branch history buffer is poisoned to speculatively steer 2610 indirect branches. 2611 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2612 2613endif 2614 2615config ARCH_HAS_ADD_PAGES 2616 def_bool y 2617 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2618 2619menu "Power management and ACPI options" 2620 2621config ARCH_HIBERNATION_HEADER 2622 def_bool y 2623 depends on HIBERNATION 2624 2625source "kernel/power/Kconfig" 2626 2627source "drivers/acpi/Kconfig" 2628 2629config X86_APM_BOOT 2630 def_bool y 2631 depends on APM 2632 2633menuconfig APM 2634 tristate "APM (Advanced Power Management) BIOS support" 2635 depends on X86_32 && PM_SLEEP 2636 help 2637 APM is a BIOS specification for saving power using several different 2638 techniques. This is mostly useful for battery powered laptops with 2639 APM compliant BIOSes. If you say Y here, the system time will be 2640 reset after a RESUME operation, the /proc/apm device will provide 2641 battery status information, and user-space programs will receive 2642 notification of APM "events" (e.g. battery status change). 2643 2644 If you select "Y" here, you can disable actual use of the APM 2645 BIOS by passing the "apm=off" option to the kernel at boot time. 2646 2647 Note that the APM support is almost completely disabled for 2648 machines with more than one CPU. 2649 2650 In order to use APM, you will need supporting software. For location 2651 and more information, read <file:Documentation/power/apm-acpi.rst> 2652 and the Battery Powered Linux mini-HOWTO, available from 2653 <http://www.tldp.org/docs.html#howto>. 2654 2655 This driver does not spin down disk drives (see the hdparm(8) 2656 manpage ("man 8 hdparm") for that), and it doesn't turn off 2657 VESA-compliant "green" monitors. 2658 2659 This driver does not support the TI 4000M TravelMate and the ACER 2660 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2661 desktop machines also don't have compliant BIOSes, and this driver 2662 may cause those machines to panic during the boot phase. 2663 2664 Generally, if you don't have a battery in your machine, there isn't 2665 much point in using this driver and you should say N. If you get 2666 random kernel OOPSes or reboots that don't seem to be related to 2667 anything, try disabling/enabling this option (or disabling/enabling 2668 APM in your BIOS). 2669 2670 Some other things you should try when experiencing seemingly random, 2671 "weird" problems: 2672 2673 1) make sure that you have enough swap space and that it is 2674 enabled. 2675 2) pass the "idle=poll" option to the kernel 2676 3) switch on floating point emulation in the kernel and pass 2677 the "no387" option to the kernel 2678 4) pass the "floppy=nodma" option to the kernel 2679 5) pass the "mem=4M" option to the kernel (thereby disabling 2680 all but the first 4 MB of RAM) 2681 6) make sure that the CPU is not over clocked. 2682 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2683 8) disable the cache from your BIOS settings 2684 9) install a fan for the video card or exchange video RAM 2685 10) install a better fan for the CPU 2686 11) exchange RAM chips 2687 12) exchange the motherboard. 2688 2689 To compile this driver as a module, choose M here: the 2690 module will be called apm. 2691 2692if APM 2693 2694config APM_IGNORE_USER_SUSPEND 2695 bool "Ignore USER SUSPEND" 2696 help 2697 This option will ignore USER SUSPEND requests. On machines with a 2698 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2699 series notebooks, it is necessary to say Y because of a BIOS bug. 2700 2701config APM_DO_ENABLE 2702 bool "Enable PM at boot time" 2703 help 2704 Enable APM features at boot time. From page 36 of the APM BIOS 2705 specification: "When disabled, the APM BIOS does not automatically 2706 power manage devices, enter the Standby State, enter the Suspend 2707 State, or take power saving steps in response to CPU Idle calls." 2708 This driver will make CPU Idle calls when Linux is idle (unless this 2709 feature is turned off -- see "Do CPU IDLE calls", below). This 2710 should always save battery power, but more complicated APM features 2711 will be dependent on your BIOS implementation. You may need to turn 2712 this option off if your computer hangs at boot time when using APM 2713 support, or if it beeps continuously instead of suspending. Turn 2714 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2715 T400CDT. This is off by default since most machines do fine without 2716 this feature. 2717 2718config APM_CPU_IDLE 2719 depends on CPU_IDLE 2720 bool "Make CPU Idle calls when idle" 2721 help 2722 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2723 On some machines, this can activate improved power savings, such as 2724 a slowed CPU clock rate, when the machine is idle. These idle calls 2725 are made after the idle loop has run for some length of time (e.g., 2726 333 mS). On some machines, this will cause a hang at boot time or 2727 whenever the CPU becomes idle. (On machines with more than one CPU, 2728 this option does nothing.) 2729 2730config APM_DISPLAY_BLANK 2731 bool "Enable console blanking using APM" 2732 help 2733 Enable console blanking using the APM. Some laptops can use this to 2734 turn off the LCD backlight when the screen blanker of the Linux 2735 virtual console blanks the screen. Note that this is only used by 2736 the virtual console screen blanker, and won't turn off the backlight 2737 when using the X Window system. This also doesn't have anything to 2738 do with your VESA-compliant power-saving monitor. Further, this 2739 option doesn't work for all laptops -- it might not turn off your 2740 backlight at all, or it might print a lot of errors to the console, 2741 especially if you are using gpm. 2742 2743config APM_ALLOW_INTS 2744 bool "Allow interrupts during APM BIOS calls" 2745 help 2746 Normally we disable external interrupts while we are making calls to 2747 the APM BIOS as a measure to lessen the effects of a badly behaving 2748 BIOS implementation. The BIOS should reenable interrupts if it 2749 needs to. Unfortunately, some BIOSes do not -- especially those in 2750 many of the newer IBM Thinkpads. If you experience hangs when you 2751 suspend, try setting this to Y. Otherwise, say N. 2752 2753endif # APM 2754 2755source "drivers/cpufreq/Kconfig" 2756 2757source "drivers/cpuidle/Kconfig" 2758 2759source "drivers/idle/Kconfig" 2760 2761endmenu 2762 2763menu "Bus options (PCI etc.)" 2764 2765choice 2766 prompt "PCI access mode" 2767 depends on X86_32 && PCI 2768 default PCI_GOANY 2769 help 2770 On PCI systems, the BIOS can be used to detect the PCI devices and 2771 determine their configuration. However, some old PCI motherboards 2772 have BIOS bugs and may crash if this is done. Also, some embedded 2773 PCI-based systems don't have any BIOS at all. Linux can also try to 2774 detect the PCI hardware directly without using the BIOS. 2775 2776 With this option, you can specify how Linux should detect the 2777 PCI devices. If you choose "BIOS", the BIOS will be used, 2778 if you choose "Direct", the BIOS won't be used, and if you 2779 choose "MMConfig", then PCI Express MMCONFIG will be used. 2780 If you choose "Any", the kernel will try MMCONFIG, then the 2781 direct access method and falls back to the BIOS if that doesn't 2782 work. If unsure, go with the default, which is "Any". 2783 2784config PCI_GOBIOS 2785 bool "BIOS" 2786 2787config PCI_GOMMCONFIG 2788 bool "MMConfig" 2789 2790config PCI_GODIRECT 2791 bool "Direct" 2792 2793config PCI_GOOLPC 2794 bool "OLPC XO-1" 2795 depends on OLPC 2796 2797config PCI_GOANY 2798 bool "Any" 2799 2800endchoice 2801 2802config PCI_BIOS 2803 def_bool y 2804 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2805 2806# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2807config PCI_DIRECT 2808 def_bool y 2809 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2810 2811config PCI_MMCONFIG 2812 bool "Support mmconfig PCI config space access" if X86_64 2813 default y 2814 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2815 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2816 2817config PCI_OLPC 2818 def_bool y 2819 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2820 2821config PCI_XEN 2822 def_bool y 2823 depends on PCI && XEN 2824 2825config MMCONF_FAM10H 2826 def_bool y 2827 depends on X86_64 && PCI_MMCONFIG && ACPI 2828 2829config PCI_CNB20LE_QUIRK 2830 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2831 depends on PCI 2832 help 2833 Read the PCI windows out of the CNB20LE host bridge. This allows 2834 PCI hotplug to work on systems with the CNB20LE chipset which do 2835 not have ACPI. 2836 2837 There's no public spec for this chipset, and this functionality 2838 is known to be incomplete. 2839 2840 You should say N unless you know you need this. 2841 2842config ISA_BUS 2843 bool "ISA bus support on modern systems" if EXPERT 2844 help 2845 Expose ISA bus device drivers and options available for selection and 2846 configuration. Enable this option if your target machine has an ISA 2847 bus. ISA is an older system, displaced by PCI and newer bus 2848 architectures -- if your target machine is modern, it probably does 2849 not have an ISA bus. 2850 2851 If unsure, say N. 2852 2853# x86_64 have no ISA slots, but can have ISA-style DMA. 2854config ISA_DMA_API 2855 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2856 default y 2857 help 2858 Enables ISA-style DMA support for devices requiring such controllers. 2859 If unsure, say Y. 2860 2861if X86_32 2862 2863config ISA 2864 bool "ISA support" 2865 help 2866 Find out whether you have ISA slots on your motherboard. ISA is the 2867 name of a bus system, i.e. the way the CPU talks to the other stuff 2868 inside your box. Other bus systems are PCI, EISA, MicroChannel 2869 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2870 newer boards don't support it. If you have ISA, say Y, otherwise N. 2871 2872config SCx200 2873 tristate "NatSemi SCx200 support" 2874 help 2875 This provides basic support for National Semiconductor's 2876 (now AMD's) Geode processors. The driver probes for the 2877 PCI-IDs of several on-chip devices, so its a good dependency 2878 for other scx200_* drivers. 2879 2880 If compiled as a module, the driver is named scx200. 2881 2882config SCx200HR_TIMER 2883 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2884 depends on SCx200 2885 default y 2886 help 2887 This driver provides a clocksource built upon the on-chip 2888 27MHz high-resolution timer. Its also a workaround for 2889 NSC Geode SC-1100's buggy TSC, which loses time when the 2890 processor goes idle (as is done by the scheduler). The 2891 other workaround is idle=poll boot option. 2892 2893config OLPC 2894 bool "One Laptop Per Child support" 2895 depends on !X86_PAE 2896 select GPIOLIB 2897 select OF 2898 select OF_PROMTREE 2899 select IRQ_DOMAIN 2900 select OLPC_EC 2901 help 2902 Add support for detecting the unique features of the OLPC 2903 XO hardware. 2904 2905config OLPC_XO1_PM 2906 bool "OLPC XO-1 Power Management" 2907 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2908 help 2909 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2910 2911config OLPC_XO1_RTC 2912 bool "OLPC XO-1 Real Time Clock" 2913 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2914 help 2915 Add support for the XO-1 real time clock, which can be used as a 2916 programmable wakeup source. 2917 2918config OLPC_XO1_SCI 2919 bool "OLPC XO-1 SCI extras" 2920 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2921 depends on INPUT=y 2922 select POWER_SUPPLY 2923 help 2924 Add support for SCI-based features of the OLPC XO-1 laptop: 2925 - EC-driven system wakeups 2926 - Power button 2927 - Ebook switch 2928 - Lid switch 2929 - AC adapter status updates 2930 - Battery status updates 2931 2932config OLPC_XO15_SCI 2933 bool "OLPC XO-1.5 SCI extras" 2934 depends on OLPC && ACPI 2935 select POWER_SUPPLY 2936 help 2937 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2938 - EC-driven system wakeups 2939 - AC adapter status updates 2940 - Battery status updates 2941 2942config ALIX 2943 bool "PCEngines ALIX System Support (LED setup)" 2944 select GPIOLIB 2945 help 2946 This option enables system support for the PCEngines ALIX. 2947 At present this just sets up LEDs for GPIO control on 2948 ALIX2/3/6 boards. However, other system specific setup should 2949 get added here. 2950 2951 Note: You must still enable the drivers for GPIO and LED support 2952 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2953 2954 Note: You have to set alix.force=1 for boards with Award BIOS. 2955 2956config NET5501 2957 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2958 select GPIOLIB 2959 help 2960 This option enables system support for the Soekris Engineering net5501. 2961 2962config GEOS 2963 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2964 select GPIOLIB 2965 depends on DMI 2966 help 2967 This option enables system support for the Traverse Technologies GEOS. 2968 2969config TS5500 2970 bool "Technologic Systems TS-5500 platform support" 2971 depends on MELAN 2972 select CHECK_SIGNATURE 2973 select NEW_LEDS 2974 select LEDS_CLASS 2975 help 2976 This option enables system support for the Technologic Systems TS-5500. 2977 2978endif # X86_32 2979 2980config AMD_NB 2981 def_bool y 2982 depends on CPU_SUP_AMD && PCI 2983 2984endmenu 2985 2986menu "Binary Emulations" 2987 2988config IA32_EMULATION 2989 bool "IA32 Emulation" 2990 depends on X86_64 2991 select ARCH_WANT_OLD_COMPAT_IPC 2992 select BINFMT_ELF 2993 select COMPAT_OLD_SIGACTION 2994 help 2995 Include code to run legacy 32-bit programs under a 2996 64-bit kernel. You should likely turn this on, unless you're 2997 100% sure that you don't have any 32-bit programs left. 2998 2999config X86_X32_ABI 3000 bool "x32 ABI for 64-bit mode" 3001 depends on X86_64 3002 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3003 # compressed debug sections to x86_x32 properly: 3004 # https://github.com/ClangBuiltLinux/linux/issues/514 3005 # https://github.com/ClangBuiltLinux/linux/issues/1141 3006 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3007 help 3008 Include code to run binaries for the x32 native 32-bit ABI 3009 for 64-bit processors. An x32 process gets access to the 3010 full 64-bit register file and wide data path while leaving 3011 pointers at 32 bits for smaller memory footprint. 3012 3013config COMPAT_32 3014 def_bool y 3015 depends on IA32_EMULATION || X86_32 3016 select HAVE_UID16 3017 select OLD_SIGSUSPEND3 3018 3019config COMPAT 3020 def_bool y 3021 depends on IA32_EMULATION || X86_X32_ABI 3022 3023config COMPAT_FOR_U64_ALIGNMENT 3024 def_bool y 3025 depends on COMPAT 3026 3027endmenu 3028 3029config HAVE_ATOMIC_IOMAP 3030 def_bool y 3031 depends on X86_32 3032 3033source "arch/x86/kvm/Kconfig" 3034 3035source "arch/x86/Kconfig.assembler" 3036