1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select HAVE_ARCH_SOFT_DIRTY 32 select MODULES_USE_ELF_RELA 33 select NEED_DMA_MAP_STATE 34 select SWIOTLB 35 select ARCH_HAS_ELFCORE_COMPAT 36 select ZONE_DMA32 37 38config FORCE_DYNAMIC_FTRACE 39 def_bool y 40 depends on X86_32 41 depends on FUNCTION_TRACER 42 select DYNAMIC_FTRACE 43 help 44 We keep the static function tracing (!DYNAMIC_FTRACE) around 45 in order to test the non static function tracing in the 46 generic code, as other architectures still use it. But we 47 only need to keep it around for x86_64. No need to keep it 48 for x86_32. For x86_32, force DYNAMIC_FTRACE. 49# 50# Arch settings 51# 52# ( Note that options that are marked 'if X86_64' could in principle be 53# ported to 32-bit as well. ) 54# 55config X86 56 def_bool y 57 # 58 # Note: keep this list sorted alphabetically 59 # 60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 62 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 63 select ARCH_32BIT_OFF_T if X86_32 64 select ARCH_CLOCKSOURCE_INIT 65 select ARCH_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_CPU_PASID if IOMMU_SVA 77 select ARCH_HAS_CURRENT_STACK_POINTER 78 select ARCH_HAS_DEBUG_VIRTUAL 79 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 80 select ARCH_HAS_DEVMEM_IS_ALLOWED 81 select ARCH_HAS_EARLY_DEBUG if KGDB 82 select ARCH_HAS_ELF_RANDOMIZE 83 select ARCH_HAS_FAST_MULTIPLIER 84 select ARCH_HAS_FORTIFY_SOURCE 85 select ARCH_HAS_GCOV_PROFILE_ALL 86 select ARCH_HAS_KCOV if X86_64 87 select ARCH_HAS_MEM_ENCRYPT 88 select ARCH_HAS_MEMBARRIER_SYNC_CORE 89 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 90 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 91 select ARCH_HAS_PMEM_API if X86_64 92 select ARCH_HAS_PTE_DEVMAP if X86_64 93 select ARCH_HAS_PTE_SPECIAL 94 select ARCH_HAS_HW_PTE_YOUNG 95 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 96 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 97 select ARCH_HAS_COPY_MC if X86_64 98 select ARCH_HAS_SET_MEMORY 99 select ARCH_HAS_SET_DIRECT_MAP 100 select ARCH_HAS_STRICT_KERNEL_RWX 101 select ARCH_HAS_STRICT_MODULE_RWX 102 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 103 select ARCH_HAS_SYSCALL_WRAPPER 104 select ARCH_HAS_UBSAN 105 select ARCH_HAS_DEBUG_WX 106 select ARCH_HAS_ZONE_DMA_SET if EXPERT 107 select ARCH_HAVE_NMI_SAFE_CMPXCHG 108 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 109 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 110 select ARCH_MIGHT_HAVE_PC_PARPORT 111 select ARCH_MIGHT_HAVE_PC_SERIO 112 select ARCH_STACKWALK 113 select ARCH_SUPPORTS_ACPI 114 select ARCH_SUPPORTS_ATOMIC_RMW 115 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 116 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 117 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 118 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 119 select ARCH_SUPPORTS_CFI_CLANG if X86_64 120 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 121 select ARCH_SUPPORTS_LTO_CLANG 122 select ARCH_SUPPORTS_LTO_CLANG_THIN 123 select ARCH_USE_BUILTIN_BSWAP 124 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64 125 select ARCH_USE_MEMTEST 126 select ARCH_USE_QUEUED_RWLOCKS 127 select ARCH_USE_QUEUED_SPINLOCKS 128 select ARCH_USE_SYM_ANNOTATIONS 129 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 130 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 131 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 132 select ARCH_WANTS_NO_INSTR 133 select ARCH_WANT_GENERAL_HUGETLB 134 select ARCH_WANT_HUGE_PMD_SHARE 135 select ARCH_WANT_LD_ORPHAN_WARN 136 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 137 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 138 select ARCH_WANTS_THP_SWAP if X86_64 139 select ARCH_HAS_PARANOID_L1D_FLUSH 140 select BUILDTIME_TABLE_SORT 141 select CLKEVT_I8253 142 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 143 select CLOCKSOURCE_WATCHDOG 144 # Word-size accesses may read uninitialized data past the trailing \0 145 # in strings and cause false KMSAN reports. 146 select DCACHE_WORD_ACCESS if !KMSAN 147 select DYNAMIC_SIGFRAME 148 select EDAC_ATOMIC_SCRUB 149 select EDAC_SUPPORT 150 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 151 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 152 select GENERIC_CLOCKEVENTS_MIN_ADJUST 153 select GENERIC_CMOS_UPDATE 154 select GENERIC_CPU_AUTOPROBE 155 select GENERIC_CPU_DEVICES 156 select GENERIC_CPU_VULNERABILITIES 157 select GENERIC_EARLY_IOREMAP 158 select GENERIC_ENTRY 159 select GENERIC_IOMAP 160 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 161 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 162 select GENERIC_IRQ_MIGRATION if SMP 163 select GENERIC_IRQ_PROBE 164 select GENERIC_IRQ_RESERVATION_MODE 165 select GENERIC_IRQ_SHOW 166 select GENERIC_PENDING_IRQ if SMP 167 select GENERIC_PTDUMP 168 select GENERIC_SMP_IDLE_THREAD 169 select GENERIC_TIME_VSYSCALL 170 select GENERIC_GETTIMEOFDAY 171 select GENERIC_VDSO_TIME_NS 172 select GUP_GET_PXX_LOW_HIGH if X86_PAE 173 select HARDIRQS_SW_RESEND 174 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 175 select HAS_IOPORT 176 select HAVE_ACPI_APEI if ACPI 177 select HAVE_ACPI_APEI_NMI if ACPI 178 select HAVE_ALIGNED_STRUCT_PAGE 179 select HAVE_ARCH_AUDITSYSCALL 180 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 181 select HAVE_ARCH_HUGE_VMALLOC if X86_64 182 select HAVE_ARCH_JUMP_LABEL 183 select HAVE_ARCH_JUMP_LABEL_RELATIVE 184 select HAVE_ARCH_KASAN if X86_64 185 select HAVE_ARCH_KASAN_VMALLOC if X86_64 186 select HAVE_ARCH_KFENCE 187 select HAVE_ARCH_KMSAN if X86_64 188 select HAVE_ARCH_KGDB 189 select HAVE_ARCH_MMAP_RND_BITS if MMU 190 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 191 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 192 select HAVE_ARCH_PREL32_RELOCATIONS 193 select HAVE_ARCH_SECCOMP_FILTER 194 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 195 select HAVE_ARCH_STACKLEAK 196 select HAVE_ARCH_TRACEHOOK 197 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 198 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 199 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 200 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 201 select HAVE_ARCH_VMAP_STACK if X86_64 202 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 203 select HAVE_ARCH_WITHIN_STACK_FRAMES 204 select HAVE_ASM_MODVERSIONS 205 select HAVE_CMPXCHG_DOUBLE 206 select HAVE_CMPXCHG_LOCAL 207 select HAVE_CONTEXT_TRACKING_USER if X86_64 208 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 209 select HAVE_C_RECORDMCOUNT 210 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 211 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 212 select HAVE_BUILDTIME_MCOUNT_SORT 213 select HAVE_DEBUG_KMEMLEAK 214 select HAVE_DMA_CONTIGUOUS 215 select HAVE_DYNAMIC_FTRACE 216 select HAVE_DYNAMIC_FTRACE_WITH_REGS 217 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 218 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 219 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 220 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 221 select HAVE_EBPF_JIT 222 select HAVE_EFFICIENT_UNALIGNED_ACCESS 223 select HAVE_EISA 224 select HAVE_EXIT_THREAD 225 select HAVE_FAST_GUP 226 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 227 select HAVE_FTRACE_MCOUNT_RECORD 228 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 229 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 230 select HAVE_FUNCTION_TRACER 231 select HAVE_GCC_PLUGINS 232 select HAVE_HW_BREAKPOINT 233 select HAVE_IOREMAP_PROT 234 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 235 select HAVE_IRQ_TIME_ACCOUNTING 236 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 237 select HAVE_KERNEL_BZIP2 238 select HAVE_KERNEL_GZIP 239 select HAVE_KERNEL_LZ4 240 select HAVE_KERNEL_LZMA 241 select HAVE_KERNEL_LZO 242 select HAVE_KERNEL_XZ 243 select HAVE_KERNEL_ZSTD 244 select HAVE_KPROBES 245 select HAVE_KPROBES_ON_FTRACE 246 select HAVE_FUNCTION_ERROR_INJECTION 247 select HAVE_KRETPROBES 248 select HAVE_RETHOOK 249 select HAVE_LIVEPATCH if X86_64 250 select HAVE_MIXED_BREAKPOINTS_REGS 251 select HAVE_MOD_ARCH_SPECIFIC 252 select HAVE_MOVE_PMD 253 select HAVE_MOVE_PUD 254 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 255 select HAVE_NMI 256 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 257 select HAVE_OBJTOOL if X86_64 258 select HAVE_OPTPROBES 259 select HAVE_PAGE_SIZE_4KB 260 select HAVE_PCSPKR_PLATFORM 261 select HAVE_PERF_EVENTS 262 select HAVE_PERF_EVENTS_NMI 263 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 264 select HAVE_PCI 265 select HAVE_PERF_REGS 266 select HAVE_PERF_USER_STACK_DUMP 267 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 268 select MMU_GATHER_MERGE_VMAS 269 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 270 select HAVE_REGS_AND_STACK_ACCESS_API 271 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 272 select HAVE_FUNCTION_ARG_ACCESS_API 273 select HAVE_SETUP_PER_CPU_AREA 274 select HAVE_SOFTIRQ_ON_OWN_STACK 275 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 276 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 277 select HAVE_STATIC_CALL 278 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 279 select HAVE_PREEMPT_DYNAMIC_CALL 280 select HAVE_RSEQ 281 select HAVE_RUST if X86_64 282 select HAVE_SYSCALL_TRACEPOINTS 283 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 284 select HAVE_UNSTABLE_SCHED_CLOCK 285 select HAVE_USER_RETURN_NOTIFIER 286 select HAVE_GENERIC_VDSO 287 select HOTPLUG_PARALLEL if SMP && X86_64 288 select HOTPLUG_SMT if SMP 289 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 290 select IRQ_FORCED_THREADING 291 select LOCK_MM_AND_FIND_VMA 292 select NEED_PER_CPU_EMBED_FIRST_CHUNK 293 select NEED_PER_CPU_PAGE_FIRST_CHUNK 294 select NEED_SG_DMA_LENGTH 295 select PCI_DOMAINS if PCI 296 select PCI_LOCKLESS_CONFIG if PCI 297 select PERF_EVENTS 298 select RTC_LIB 299 select RTC_MC146818_LIB 300 select SPARSE_IRQ 301 select SYSCTL_EXCEPTION_TRACE 302 select THREAD_INFO_IN_TASK 303 select TRACE_IRQFLAGS_SUPPORT 304 select TRACE_IRQFLAGS_NMI_SUPPORT 305 select USER_STACKTRACE_SUPPORT 306 select HAVE_ARCH_KCSAN if X86_64 307 select PROC_PID_ARCH_STATUS if PROC_FS 308 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 309 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 310 select FUNCTION_ALIGNMENT_4B 311 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 312 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 313 314config INSTRUCTION_DECODER 315 def_bool y 316 depends on KPROBES || PERF_EVENTS || UPROBES 317 318config OUTPUT_FORMAT 319 string 320 default "elf32-i386" if X86_32 321 default "elf64-x86-64" if X86_64 322 323config LOCKDEP_SUPPORT 324 def_bool y 325 326config STACKTRACE_SUPPORT 327 def_bool y 328 329config MMU 330 def_bool y 331 332config ARCH_MMAP_RND_BITS_MIN 333 default 28 if 64BIT 334 default 8 335 336config ARCH_MMAP_RND_BITS_MAX 337 default 32 if 64BIT 338 default 16 339 340config ARCH_MMAP_RND_COMPAT_BITS_MIN 341 default 8 342 343config ARCH_MMAP_RND_COMPAT_BITS_MAX 344 default 16 345 346config SBUS 347 bool 348 349config GENERIC_ISA_DMA 350 def_bool y 351 depends on ISA_DMA_API 352 353config GENERIC_CSUM 354 bool 355 default y if KMSAN || KASAN 356 357config GENERIC_BUG 358 def_bool y 359 depends on BUG 360 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 361 362config GENERIC_BUG_RELATIVE_POINTERS 363 bool 364 365config ARCH_MAY_HAVE_PC_FDC 366 def_bool y 367 depends on ISA_DMA_API 368 369config GENERIC_CALIBRATE_DELAY 370 def_bool y 371 372config ARCH_HAS_CPU_RELAX 373 def_bool y 374 375config ARCH_HIBERNATION_POSSIBLE 376 def_bool y 377 378config ARCH_SUSPEND_POSSIBLE 379 def_bool y 380 381config AUDIT_ARCH 382 def_bool y if X86_64 383 384config KASAN_SHADOW_OFFSET 385 hex 386 depends on KASAN 387 default 0xdffffc0000000000 388 389config HAVE_INTEL_TXT 390 def_bool y 391 depends on INTEL_IOMMU && ACPI 392 393config X86_64_SMP 394 def_bool y 395 depends on X86_64 && SMP 396 397config ARCH_SUPPORTS_UPROBES 398 def_bool y 399 400config FIX_EARLYCON_MEM 401 def_bool y 402 403config DYNAMIC_PHYSICAL_MASK 404 bool 405 406config PGTABLE_LEVELS 407 int 408 default 5 if X86_5LEVEL 409 default 4 if X86_64 410 default 3 if X86_PAE 411 default 2 412 413config CC_HAS_SANE_STACKPROTECTOR 414 bool 415 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 416 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 417 help 418 We have to make sure stack protector is unconditionally disabled if 419 the compiler produces broken code or if it does not let us control 420 the segment on 32-bit kernels. 421 422menu "Processor type and features" 423 424config SMP 425 bool "Symmetric multi-processing support" 426 help 427 This enables support for systems with more than one CPU. If you have 428 a system with only one CPU, say N. If you have a system with more 429 than one CPU, say Y. 430 431 If you say N here, the kernel will run on uni- and multiprocessor 432 machines, but will use only one CPU of a multiprocessor machine. If 433 you say Y here, the kernel will run on many, but not all, 434 uniprocessor machines. On a uniprocessor machine, the kernel 435 will run faster if you say N here. 436 437 Note that if you say Y here and choose architecture "586" or 438 "Pentium" under "Processor family", the kernel will not work on 486 439 architectures. Similarly, multiprocessor kernels for the "PPro" 440 architecture may not work on all Pentium based boards. 441 442 People using multiprocessor machines who say Y here should also say 443 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 444 Management" code will be disabled if you say Y here. 445 446 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 447 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 448 <http://www.tldp.org/docs.html#howto>. 449 450 If you don't know what to do here, say N. 451 452config X86_X2APIC 453 bool "Support x2apic" 454 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 455 help 456 This enables x2apic support on CPUs that have this feature. 457 458 This allows 32-bit apic IDs (so it can support very large systems), 459 and accesses the local apic via MSRs not via mmio. 460 461 Some Intel systems circa 2022 and later are locked into x2APIC mode 462 and can not fall back to the legacy APIC modes if SGX or TDX are 463 enabled in the BIOS. They will boot with very reduced functionality 464 without enabling this option. 465 466 If you don't know what to do here, say N. 467 468config X86_MPPARSE 469 bool "Enable MPS table" if ACPI 470 default y 471 depends on X86_LOCAL_APIC 472 help 473 For old smp systems that do not have proper acpi support. Newer systems 474 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 475 476config X86_CPU_RESCTRL 477 bool "x86 CPU resource control support" 478 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 479 select KERNFS 480 select PROC_CPU_RESCTRL if PROC_FS 481 help 482 Enable x86 CPU resource control support. 483 484 Provide support for the allocation and monitoring of system resources 485 usage by the CPU. 486 487 Intel calls this Intel Resource Director Technology 488 (Intel(R) RDT). More information about RDT can be found in the 489 Intel x86 Architecture Software Developer Manual. 490 491 AMD calls this AMD Platform Quality of Service (AMD QoS). 492 More information about AMD QoS can be found in the AMD64 Technology 493 Platform Quality of Service Extensions manual. 494 495 Say N if unsure. 496 497config X86_FRED 498 bool "Flexible Return and Event Delivery" 499 depends on X86_64 500 help 501 When enabled, try to use Flexible Return and Event Delivery 502 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 503 ring transitions and exception/interrupt handling if the 504 system supports. 505 506if X86_32 507config X86_BIGSMP 508 bool "Support for big SMP systems with more than 8 CPUs" 509 depends on SMP 510 help 511 This option is needed for the systems that have more than 8 CPUs. 512 513config X86_EXTENDED_PLATFORM 514 bool "Support for extended (non-PC) x86 platforms" 515 default y 516 help 517 If you disable this option then the kernel will only support 518 standard PC platforms. (which covers the vast majority of 519 systems out there.) 520 521 If you enable this option then you'll be able to select support 522 for the following (non-PC) 32 bit x86 platforms: 523 Goldfish (Android emulator) 524 AMD Elan 525 RDC R-321x SoC 526 SGI 320/540 (Visual Workstation) 527 STA2X11-based (e.g. Northville) 528 Moorestown MID devices 529 530 If you have one of these systems, or if you want to build a 531 generic distribution kernel, say Y here - otherwise say N. 532endif # X86_32 533 534if X86_64 535config X86_EXTENDED_PLATFORM 536 bool "Support for extended (non-PC) x86 platforms" 537 default y 538 help 539 If you disable this option then the kernel will only support 540 standard PC platforms. (which covers the vast majority of 541 systems out there.) 542 543 If you enable this option then you'll be able to select support 544 for the following (non-PC) 64 bit x86 platforms: 545 Numascale NumaChip 546 ScaleMP vSMP 547 SGI Ultraviolet 548 549 If you have one of these systems, or if you want to build a 550 generic distribution kernel, say Y here - otherwise say N. 551endif # X86_64 552# This is an alphabetically sorted list of 64 bit extended platforms 553# Please maintain the alphabetic order if and when there are additions 554config X86_NUMACHIP 555 bool "Numascale NumaChip" 556 depends on X86_64 557 depends on X86_EXTENDED_PLATFORM 558 depends on NUMA 559 depends on SMP 560 depends on X86_X2APIC 561 depends on PCI_MMCONFIG 562 help 563 Adds support for Numascale NumaChip large-SMP systems. Needed to 564 enable more than ~168 cores. 565 If you don't have one of these, you should say N here. 566 567config X86_VSMP 568 bool "ScaleMP vSMP" 569 select HYPERVISOR_GUEST 570 select PARAVIRT 571 depends on X86_64 && PCI 572 depends on X86_EXTENDED_PLATFORM 573 depends on SMP 574 help 575 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 576 supposed to run on these EM64T-based machines. Only choose this option 577 if you have one of these machines. 578 579config X86_UV 580 bool "SGI Ultraviolet" 581 depends on X86_64 582 depends on X86_EXTENDED_PLATFORM 583 depends on NUMA 584 depends on EFI 585 depends on KEXEC_CORE 586 depends on X86_X2APIC 587 depends on PCI 588 help 589 This option is needed in order to support SGI Ultraviolet systems. 590 If you don't have one of these, you should say N here. 591 592# Following is an alphabetically sorted list of 32 bit extended platforms 593# Please maintain the alphabetic order if and when there are additions 594 595config X86_GOLDFISH 596 bool "Goldfish (Virtual Platform)" 597 depends on X86_EXTENDED_PLATFORM 598 help 599 Enable support for the Goldfish virtual platform used primarily 600 for Android development. Unless you are building for the Android 601 Goldfish emulator say N here. 602 603config X86_INTEL_CE 604 bool "CE4100 TV platform" 605 depends on PCI 606 depends on PCI_GODIRECT 607 depends on X86_IO_APIC 608 depends on X86_32 609 depends on X86_EXTENDED_PLATFORM 610 select X86_REBOOTFIXUPS 611 select OF 612 select OF_EARLY_FLATTREE 613 help 614 Select for the Intel CE media processor (CE4100) SOC. 615 This option compiles in support for the CE4100 SOC for settop 616 boxes and media devices. 617 618config X86_INTEL_MID 619 bool "Intel MID platform support" 620 depends on X86_EXTENDED_PLATFORM 621 depends on X86_PLATFORM_DEVICES 622 depends on PCI 623 depends on X86_64 || (PCI_GOANY && X86_32) 624 depends on X86_IO_APIC 625 select I2C 626 select DW_APB_TIMER 627 select INTEL_SCU_PCI 628 help 629 Select to build a kernel capable of supporting Intel MID (Mobile 630 Internet Device) platform systems which do not have the PCI legacy 631 interfaces. If you are building for a PC class system say N here. 632 633 Intel MID platforms are based on an Intel processor and chipset which 634 consume less power than most of the x86 derivatives. 635 636config X86_INTEL_QUARK 637 bool "Intel Quark platform support" 638 depends on X86_32 639 depends on X86_EXTENDED_PLATFORM 640 depends on X86_PLATFORM_DEVICES 641 depends on X86_TSC 642 depends on PCI 643 depends on PCI_GOANY 644 depends on X86_IO_APIC 645 select IOSF_MBI 646 select INTEL_IMR 647 select COMMON_CLK 648 help 649 Select to include support for Quark X1000 SoC. 650 Say Y here if you have a Quark based system such as the Arduino 651 compatible Intel Galileo. 652 653config X86_INTEL_LPSS 654 bool "Intel Low Power Subsystem Support" 655 depends on X86 && ACPI && PCI 656 select COMMON_CLK 657 select PINCTRL 658 select IOSF_MBI 659 help 660 Select to build support for Intel Low Power Subsystem such as 661 found on Intel Lynxpoint PCH. Selecting this option enables 662 things like clock tree (common clock framework) and pincontrol 663 which are needed by the LPSS peripheral drivers. 664 665config X86_AMD_PLATFORM_DEVICE 666 bool "AMD ACPI2Platform devices support" 667 depends on ACPI 668 select COMMON_CLK 669 select PINCTRL 670 help 671 Select to interpret AMD specific ACPI device to platform device 672 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 673 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 674 implemented under PINCTRL subsystem. 675 676config IOSF_MBI 677 tristate "Intel SoC IOSF Sideband support for SoC platforms" 678 depends on PCI 679 help 680 This option enables sideband register access support for Intel SoC 681 platforms. On these platforms the IOSF sideband is used in lieu of 682 MSR's for some register accesses, mostly but not limited to thermal 683 and power. Drivers may query the availability of this device to 684 determine if they need the sideband in order to work on these 685 platforms. The sideband is available on the following SoC products. 686 This list is not meant to be exclusive. 687 - BayTrail 688 - Braswell 689 - Quark 690 691 You should say Y if you are running a kernel on one of these SoC's. 692 693config IOSF_MBI_DEBUG 694 bool "Enable IOSF sideband access through debugfs" 695 depends on IOSF_MBI && DEBUG_FS 696 help 697 Select this option to expose the IOSF sideband access registers (MCR, 698 MDR, MCRX) through debugfs to write and read register information from 699 different units on the SoC. This is most useful for obtaining device 700 state information for debug and analysis. As this is a general access 701 mechanism, users of this option would have specific knowledge of the 702 device they want to access. 703 704 If you don't require the option or are in doubt, say N. 705 706config X86_RDC321X 707 bool "RDC R-321x SoC" 708 depends on X86_32 709 depends on X86_EXTENDED_PLATFORM 710 select M486 711 select X86_REBOOTFIXUPS 712 help 713 This option is needed for RDC R-321x system-on-chip, also known 714 as R-8610-(G). 715 If you don't have one of these chips, you should say N here. 716 717config X86_32_NON_STANDARD 718 bool "Support non-standard 32-bit SMP architectures" 719 depends on X86_32 && SMP 720 depends on X86_EXTENDED_PLATFORM 721 help 722 This option compiles in the bigsmp and STA2X11 default 723 subarchitectures. It is intended for a generic binary 724 kernel. If you select them all, kernel will probe it one by 725 one and will fallback to default. 726 727# Alphabetically sorted list of Non standard 32 bit platforms 728 729config X86_SUPPORTS_MEMORY_FAILURE 730 def_bool y 731 # MCE code calls memory_failure(): 732 depends on X86_MCE 733 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 734 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 735 depends on X86_64 || !SPARSEMEM 736 select ARCH_SUPPORTS_MEMORY_FAILURE 737 738config STA2X11 739 bool "STA2X11 Companion Chip Support" 740 depends on X86_32_NON_STANDARD && PCI 741 select SWIOTLB 742 select MFD_STA2X11 743 select GPIOLIB 744 help 745 This adds support for boards based on the STA2X11 IO-Hub, 746 a.k.a. "ConneXt". The chip is used in place of the standard 747 PC chipset, so all "standard" peripherals are missing. If this 748 option is selected the kernel will still be able to boot on 749 standard PC machines. 750 751config X86_32_IRIS 752 tristate "Eurobraille/Iris poweroff module" 753 depends on X86_32 754 help 755 The Iris machines from EuroBraille do not have APM or ACPI support 756 to shut themselves down properly. A special I/O sequence is 757 needed to do so, which is what this module does at 758 kernel shutdown. 759 760 This is only for Iris machines from EuroBraille. 761 762 If unused, say N. 763 764config SCHED_OMIT_FRAME_POINTER 765 def_bool y 766 prompt "Single-depth WCHAN output" 767 depends on X86 768 help 769 Calculate simpler /proc/<PID>/wchan values. If this option 770 is disabled then wchan values will recurse back to the 771 caller function. This provides more accurate wchan values, 772 at the expense of slightly more scheduling overhead. 773 774 If in doubt, say "Y". 775 776menuconfig HYPERVISOR_GUEST 777 bool "Linux guest support" 778 help 779 Say Y here to enable options for running Linux under various hyper- 780 visors. This option enables basic hypervisor detection and platform 781 setup. 782 783 If you say N, all options in this submenu will be skipped and 784 disabled, and Linux guest support won't be built in. 785 786if HYPERVISOR_GUEST 787 788config PARAVIRT 789 bool "Enable paravirtualization code" 790 depends on HAVE_STATIC_CALL 791 help 792 This changes the kernel so it can modify itself when it is run 793 under a hypervisor, potentially improving performance significantly 794 over full virtualization. However, when run without a hypervisor 795 the kernel is theoretically slower and slightly larger. 796 797config PARAVIRT_XXL 798 bool 799 800config PARAVIRT_DEBUG 801 bool "paravirt-ops debugging" 802 depends on PARAVIRT && DEBUG_KERNEL 803 help 804 Enable to debug paravirt_ops internals. Specifically, BUG if 805 a paravirt_op is missing when it is called. 806 807config PARAVIRT_SPINLOCKS 808 bool "Paravirtualization layer for spinlocks" 809 depends on PARAVIRT && SMP 810 help 811 Paravirtualized spinlocks allow a pvops backend to replace the 812 spinlock implementation with something virtualization-friendly 813 (for example, block the virtual CPU rather than spinning). 814 815 It has a minimal impact on native kernels and gives a nice performance 816 benefit on paravirtualized KVM / Xen kernels. 817 818 If you are unsure how to answer this question, answer Y. 819 820config X86_HV_CALLBACK_VECTOR 821 def_bool n 822 823source "arch/x86/xen/Kconfig" 824 825config KVM_GUEST 826 bool "KVM Guest support (including kvmclock)" 827 depends on PARAVIRT 828 select PARAVIRT_CLOCK 829 select ARCH_CPUIDLE_HALTPOLL 830 select X86_HV_CALLBACK_VECTOR 831 default y 832 help 833 This option enables various optimizations for running under the KVM 834 hypervisor. It includes a paravirtualized clock, so that instead 835 of relying on a PIT (or probably other) emulation by the 836 underlying device model, the host provides the guest with 837 timing infrastructure such as time of day, and system time 838 839config ARCH_CPUIDLE_HALTPOLL 840 def_bool n 841 prompt "Disable host haltpoll when loading haltpoll driver" 842 help 843 If virtualized under KVM, disable host haltpoll. 844 845config PVH 846 bool "Support for running PVH guests" 847 help 848 This option enables the PVH entry point for guest virtual machines 849 as specified in the x86/HVM direct boot ABI. 850 851config PARAVIRT_TIME_ACCOUNTING 852 bool "Paravirtual steal time accounting" 853 depends on PARAVIRT 854 help 855 Select this option to enable fine granularity task steal time 856 accounting. Time spent executing other tasks in parallel with 857 the current vCPU is discounted from the vCPU power. To account for 858 that, there can be a small performance impact. 859 860 If in doubt, say N here. 861 862config PARAVIRT_CLOCK 863 bool 864 865config JAILHOUSE_GUEST 866 bool "Jailhouse non-root cell support" 867 depends on X86_64 && PCI 868 select X86_PM_TIMER 869 help 870 This option allows to run Linux as guest in a Jailhouse non-root 871 cell. You can leave this option disabled if you only want to start 872 Jailhouse and run Linux afterwards in the root cell. 873 874config ACRN_GUEST 875 bool "ACRN Guest support" 876 depends on X86_64 877 select X86_HV_CALLBACK_VECTOR 878 help 879 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 880 a flexible, lightweight reference open-source hypervisor, built with 881 real-time and safety-criticality in mind. It is built for embedded 882 IOT with small footprint and real-time features. More details can be 883 found in https://projectacrn.org/. 884 885config INTEL_TDX_GUEST 886 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 887 depends on X86_64 && CPU_SUP_INTEL 888 depends on X86_X2APIC 889 depends on EFI_STUB 890 select ARCH_HAS_CC_PLATFORM 891 select X86_MEM_ENCRYPT 892 select X86_MCE 893 select UNACCEPTED_MEMORY 894 help 895 Support running as a guest under Intel TDX. Without this support, 896 the guest kernel can not boot or run under TDX. 897 TDX includes memory encryption and integrity capabilities 898 which protect the confidentiality and integrity of guest 899 memory contents and CPU state. TDX guests are protected from 900 some attacks from the VMM. 901 902endif # HYPERVISOR_GUEST 903 904source "arch/x86/Kconfig.cpu" 905 906config HPET_TIMER 907 def_bool X86_64 908 prompt "HPET Timer Support" if X86_32 909 help 910 Use the IA-PC HPET (High Precision Event Timer) to manage 911 time in preference to the PIT and RTC, if a HPET is 912 present. 913 HPET is the next generation timer replacing legacy 8254s. 914 The HPET provides a stable time base on SMP 915 systems, unlike the TSC, but it is more expensive to access, 916 as it is off-chip. The interface used is documented 917 in the HPET spec, revision 1. 918 919 You can safely choose Y here. However, HPET will only be 920 activated if the platform and the BIOS support this feature. 921 Otherwise the 8254 will be used for timing services. 922 923 Choose N to continue using the legacy 8254 timer. 924 925config HPET_EMULATE_RTC 926 def_bool y 927 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 928 929# Mark as expert because too many people got it wrong. 930# The code disables itself when not needed. 931config DMI 932 default y 933 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 934 bool "Enable DMI scanning" if EXPERT 935 help 936 Enabled scanning of DMI to identify machine quirks. Say Y 937 here unless you have verified that your setup is not 938 affected by entries in the DMI blacklist. Required by PNP 939 BIOS code. 940 941config GART_IOMMU 942 bool "Old AMD GART IOMMU support" 943 select DMA_OPS 944 select IOMMU_HELPER 945 select SWIOTLB 946 depends on X86_64 && PCI && AMD_NB 947 help 948 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 949 GART based hardware IOMMUs. 950 951 The GART supports full DMA access for devices with 32-bit access 952 limitations, on systems with more than 3 GB. This is usually needed 953 for USB, sound, many IDE/SATA chipsets and some other devices. 954 955 Newer systems typically have a modern AMD IOMMU, supported via 956 the CONFIG_AMD_IOMMU=y config option. 957 958 In normal configurations this driver is only active when needed: 959 there's more than 3 GB of memory and the system contains a 960 32-bit limited device. 961 962 If unsure, say Y. 963 964config BOOT_VESA_SUPPORT 965 bool 966 help 967 If true, at least one selected framebuffer driver can take advantage 968 of VESA video modes set at an early boot stage via the vga= parameter. 969 970config MAXSMP 971 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 972 depends on X86_64 && SMP && DEBUG_KERNEL 973 select CPUMASK_OFFSTACK 974 help 975 Enable maximum number of CPUS and NUMA Nodes for this architecture. 976 If unsure, say N. 977 978# 979# The maximum number of CPUs supported: 980# 981# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 982# and which can be configured interactively in the 983# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 984# 985# The ranges are different on 32-bit and 64-bit kernels, depending on 986# hardware capabilities and scalability features of the kernel. 987# 988# ( If MAXSMP is enabled we just use the highest possible value and disable 989# interactive configuration. ) 990# 991 992config NR_CPUS_RANGE_BEGIN 993 int 994 default NR_CPUS_RANGE_END if MAXSMP 995 default 1 if !SMP 996 default 2 997 998config NR_CPUS_RANGE_END 999 int 1000 depends on X86_32 1001 default 64 if SMP && X86_BIGSMP 1002 default 8 if SMP && !X86_BIGSMP 1003 default 1 if !SMP 1004 1005config NR_CPUS_RANGE_END 1006 int 1007 depends on X86_64 1008 default 8192 if SMP && CPUMASK_OFFSTACK 1009 default 512 if SMP && !CPUMASK_OFFSTACK 1010 default 1 if !SMP 1011 1012config NR_CPUS_DEFAULT 1013 int 1014 depends on X86_32 1015 default 32 if X86_BIGSMP 1016 default 8 if SMP 1017 default 1 if !SMP 1018 1019config NR_CPUS_DEFAULT 1020 int 1021 depends on X86_64 1022 default 8192 if MAXSMP 1023 default 64 if SMP 1024 default 1 if !SMP 1025 1026config NR_CPUS 1027 int "Maximum number of CPUs" if SMP && !MAXSMP 1028 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1029 default NR_CPUS_DEFAULT 1030 help 1031 This allows you to specify the maximum number of CPUs which this 1032 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1033 supported value is 8192, otherwise the maximum value is 512. The 1034 minimum value which makes sense is 2. 1035 1036 This is purely to save memory: each supported CPU adds about 8KB 1037 to the kernel image. 1038 1039config SCHED_CLUSTER 1040 bool "Cluster scheduler support" 1041 depends on SMP 1042 default y 1043 help 1044 Cluster scheduler support improves the CPU scheduler's decision 1045 making when dealing with machines that have clusters of CPUs. 1046 Cluster usually means a couple of CPUs which are placed closely 1047 by sharing mid-level caches, last-level cache tags or internal 1048 busses. 1049 1050config SCHED_SMT 1051 def_bool y if SMP 1052 1053config SCHED_MC 1054 def_bool y 1055 prompt "Multi-core scheduler support" 1056 depends on SMP 1057 help 1058 Multi-core scheduler support improves the CPU scheduler's decision 1059 making when dealing with multi-core CPU chips at a cost of slightly 1060 increased overhead in some places. If unsure say N here. 1061 1062config SCHED_MC_PRIO 1063 bool "CPU core priorities scheduler support" 1064 depends on SCHED_MC 1065 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1066 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1067 select CPU_FREQ 1068 default y 1069 help 1070 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1071 core ordering determined at manufacturing time, which allows 1072 certain cores to reach higher turbo frequencies (when running 1073 single threaded workloads) than others. 1074 1075 Enabling this kernel feature teaches the scheduler about 1076 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1077 scheduler's CPU selection logic accordingly, so that higher 1078 overall system performance can be achieved. 1079 1080 This feature will have no effect on CPUs without this feature. 1081 1082 If unsure say Y here. 1083 1084config UP_LATE_INIT 1085 def_bool y 1086 depends on !SMP && X86_LOCAL_APIC 1087 1088config X86_UP_APIC 1089 bool "Local APIC support on uniprocessors" if !PCI_MSI 1090 default PCI_MSI 1091 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1092 help 1093 A local APIC (Advanced Programmable Interrupt Controller) is an 1094 integrated interrupt controller in the CPU. If you have a single-CPU 1095 system which has a processor with a local APIC, you can say Y here to 1096 enable and use it. If you say Y here even though your machine doesn't 1097 have a local APIC, then the kernel will still run with no slowdown at 1098 all. The local APIC supports CPU-generated self-interrupts (timer, 1099 performance counters), and the NMI watchdog which detects hard 1100 lockups. 1101 1102config X86_UP_IOAPIC 1103 bool "IO-APIC support on uniprocessors" 1104 depends on X86_UP_APIC 1105 help 1106 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1107 SMP-capable replacement for PC-style interrupt controllers. Most 1108 SMP systems and many recent uniprocessor systems have one. 1109 1110 If you have a single-CPU system with an IO-APIC, you can say Y here 1111 to use it. If you say Y here even though your machine doesn't have 1112 an IO-APIC, then the kernel will still run with no slowdown at all. 1113 1114config X86_LOCAL_APIC 1115 def_bool y 1116 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1117 select IRQ_DOMAIN_HIERARCHY 1118 1119config X86_IO_APIC 1120 def_bool y 1121 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1122 1123config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1124 bool "Reroute for broken boot IRQs" 1125 depends on X86_IO_APIC 1126 help 1127 This option enables a workaround that fixes a source of 1128 spurious interrupts. This is recommended when threaded 1129 interrupt handling is used on systems where the generation of 1130 superfluous "boot interrupts" cannot be disabled. 1131 1132 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1133 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1134 kernel does during interrupt handling). On chipsets where this 1135 boot IRQ generation cannot be disabled, this workaround keeps 1136 the original IRQ line masked so that only the equivalent "boot 1137 IRQ" is delivered to the CPUs. The workaround also tells the 1138 kernel to set up the IRQ handler on the boot IRQ line. In this 1139 way only one interrupt is delivered to the kernel. Otherwise 1140 the spurious second interrupt may cause the kernel to bring 1141 down (vital) interrupt lines. 1142 1143 Only affects "broken" chipsets. Interrupt sharing may be 1144 increased on these systems. 1145 1146config X86_MCE 1147 bool "Machine Check / overheating reporting" 1148 select GENERIC_ALLOCATOR 1149 default y 1150 help 1151 Machine Check support allows the processor to notify the 1152 kernel if it detects a problem (e.g. overheating, data corruption). 1153 The action the kernel takes depends on the severity of the problem, 1154 ranging from warning messages to halting the machine. 1155 1156config X86_MCELOG_LEGACY 1157 bool "Support for deprecated /dev/mcelog character device" 1158 depends on X86_MCE 1159 help 1160 Enable support for /dev/mcelog which is needed by the old mcelog 1161 userspace logging daemon. Consider switching to the new generation 1162 rasdaemon solution. 1163 1164config X86_MCE_INTEL 1165 def_bool y 1166 prompt "Intel MCE features" 1167 depends on X86_MCE && X86_LOCAL_APIC 1168 help 1169 Additional support for intel specific MCE features such as 1170 the thermal monitor. 1171 1172config X86_MCE_AMD 1173 def_bool y 1174 prompt "AMD MCE features" 1175 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1176 help 1177 Additional support for AMD specific MCE features such as 1178 the DRAM Error Threshold. 1179 1180config X86_ANCIENT_MCE 1181 bool "Support for old Pentium 5 / WinChip machine checks" 1182 depends on X86_32 && X86_MCE 1183 help 1184 Include support for machine check handling on old Pentium 5 or WinChip 1185 systems. These typically need to be enabled explicitly on the command 1186 line. 1187 1188config X86_MCE_THRESHOLD 1189 depends on X86_MCE_AMD || X86_MCE_INTEL 1190 def_bool y 1191 1192config X86_MCE_INJECT 1193 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1194 tristate "Machine check injector support" 1195 help 1196 Provide support for injecting machine checks for testing purposes. 1197 If you don't know what a machine check is and you don't do kernel 1198 QA it is safe to say n. 1199 1200source "arch/x86/events/Kconfig" 1201 1202config X86_LEGACY_VM86 1203 bool "Legacy VM86 support" 1204 depends on X86_32 1205 help 1206 This option allows user programs to put the CPU into V8086 1207 mode, which is an 80286-era approximation of 16-bit real mode. 1208 1209 Some very old versions of X and/or vbetool require this option 1210 for user mode setting. Similarly, DOSEMU will use it if 1211 available to accelerate real mode DOS programs. However, any 1212 recent version of DOSEMU, X, or vbetool should be fully 1213 functional even without kernel VM86 support, as they will all 1214 fall back to software emulation. Nevertheless, if you are using 1215 a 16-bit DOS program where 16-bit performance matters, vm86 1216 mode might be faster than emulation and you might want to 1217 enable this option. 1218 1219 Note that any app that works on a 64-bit kernel is unlikely to 1220 need this option, as 64-bit kernels don't, and can't, support 1221 V8086 mode. This option is also unrelated to 16-bit protected 1222 mode and is not needed to run most 16-bit programs under Wine. 1223 1224 Enabling this option increases the complexity of the kernel 1225 and slows down exception handling a tiny bit. 1226 1227 If unsure, say N here. 1228 1229config VM86 1230 bool 1231 default X86_LEGACY_VM86 1232 1233config X86_16BIT 1234 bool "Enable support for 16-bit segments" if EXPERT 1235 default y 1236 depends on MODIFY_LDT_SYSCALL 1237 help 1238 This option is required by programs like Wine to run 16-bit 1239 protected mode legacy code on x86 processors. Disabling 1240 this option saves about 300 bytes on i386, or around 6K text 1241 plus 16K runtime memory on x86-64, 1242 1243config X86_ESPFIX32 1244 def_bool y 1245 depends on X86_16BIT && X86_32 1246 1247config X86_ESPFIX64 1248 def_bool y 1249 depends on X86_16BIT && X86_64 1250 1251config X86_VSYSCALL_EMULATION 1252 bool "Enable vsyscall emulation" if EXPERT 1253 default y 1254 depends on X86_64 1255 help 1256 This enables emulation of the legacy vsyscall page. Disabling 1257 it is roughly equivalent to booting with vsyscall=none, except 1258 that it will also disable the helpful warning if a program 1259 tries to use a vsyscall. With this option set to N, offending 1260 programs will just segfault, citing addresses of the form 1261 0xffffffffff600?00. 1262 1263 This option is required by many programs built before 2013, and 1264 care should be used even with newer programs if set to N. 1265 1266 Disabling this option saves about 7K of kernel size and 1267 possibly 4K of additional runtime pagetable memory. 1268 1269config X86_IOPL_IOPERM 1270 bool "IOPERM and IOPL Emulation" 1271 default y 1272 help 1273 This enables the ioperm() and iopl() syscalls which are necessary 1274 for legacy applications. 1275 1276 Legacy IOPL support is an overbroad mechanism which allows user 1277 space aside of accessing all 65536 I/O ports also to disable 1278 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1279 capabilities and permission from potentially active security 1280 modules. 1281 1282 The emulation restricts the functionality of the syscall to 1283 only allowing the full range I/O port access, but prevents the 1284 ability to disable interrupts from user space which would be 1285 granted if the hardware IOPL mechanism would be used. 1286 1287config TOSHIBA 1288 tristate "Toshiba Laptop support" 1289 depends on X86_32 1290 help 1291 This adds a driver to safely access the System Management Mode of 1292 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1293 not work on models with a Phoenix BIOS. The System Management Mode 1294 is used to set the BIOS and power saving options on Toshiba portables. 1295 1296 For information on utilities to make use of this driver see the 1297 Toshiba Linux utilities web site at: 1298 <http://www.buzzard.org.uk/toshiba/>. 1299 1300 Say Y if you intend to run this kernel on a Toshiba portable. 1301 Say N otherwise. 1302 1303config X86_REBOOTFIXUPS 1304 bool "Enable X86 board specific fixups for reboot" 1305 depends on X86_32 1306 help 1307 This enables chipset and/or board specific fixups to be done 1308 in order to get reboot to work correctly. This is only needed on 1309 some combinations of hardware and BIOS. The symptom, for which 1310 this config is intended, is when reboot ends with a stalled/hung 1311 system. 1312 1313 Currently, the only fixup is for the Geode machines using 1314 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1315 1316 Say Y if you want to enable the fixup. Currently, it's safe to 1317 enable this option even if you don't need it. 1318 Say N otherwise. 1319 1320config MICROCODE 1321 def_bool y 1322 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1323 1324config MICROCODE_INITRD32 1325 def_bool y 1326 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1327 1328config MICROCODE_LATE_LOADING 1329 bool "Late microcode loading (DANGEROUS)" 1330 default n 1331 depends on MICROCODE && SMP 1332 help 1333 Loading microcode late, when the system is up and executing instructions 1334 is a tricky business and should be avoided if possible. Just the sequence 1335 of synchronizing all cores and SMT threads is one fragile dance which does 1336 not guarantee that cores might not softlock after the loading. Therefore, 1337 use this at your own risk. Late loading taints the kernel unless the 1338 microcode header indicates that it is safe for late loading via the 1339 minimal revision check. This minimal revision check can be enforced on 1340 the kernel command line with "microcode.minrev=Y". 1341 1342config MICROCODE_LATE_FORCE_MINREV 1343 bool "Enforce late microcode loading minimal revision check" 1344 default n 1345 depends on MICROCODE_LATE_LOADING 1346 help 1347 To prevent that users load microcode late which modifies already 1348 in use features, newer microcode patches have a minimum revision field 1349 in the microcode header, which tells the kernel which minimum 1350 revision must be active in the CPU to safely load that new microcode 1351 late into the running system. If disabled the check will not 1352 be enforced but the kernel will be tainted when the minimal 1353 revision check fails. 1354 1355 This minimal revision check can also be controlled via the 1356 "microcode.minrev" parameter on the kernel command line. 1357 1358 If unsure say Y. 1359 1360config X86_MSR 1361 tristate "/dev/cpu/*/msr - Model-specific register support" 1362 help 1363 This device gives privileged processes access to the x86 1364 Model-Specific Registers (MSRs). It is a character device with 1365 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1366 MSR accesses are directed to a specific CPU on multi-processor 1367 systems. 1368 1369config X86_CPUID 1370 tristate "/dev/cpu/*/cpuid - CPU information support" 1371 help 1372 This device gives processes access to the x86 CPUID instruction to 1373 be executed on a specific processor. It is a character device 1374 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1375 /dev/cpu/31/cpuid. 1376 1377choice 1378 prompt "High Memory Support" 1379 default HIGHMEM4G 1380 depends on X86_32 1381 1382config NOHIGHMEM 1383 bool "off" 1384 help 1385 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1386 However, the address space of 32-bit x86 processors is only 4 1387 Gigabytes large. That means that, if you have a large amount of 1388 physical memory, not all of it can be "permanently mapped" by the 1389 kernel. The physical memory that's not permanently mapped is called 1390 "high memory". 1391 1392 If you are compiling a kernel which will never run on a machine with 1393 more than 1 Gigabyte total physical RAM, answer "off" here (default 1394 choice and suitable for most users). This will result in a "3GB/1GB" 1395 split: 3GB are mapped so that each process sees a 3GB virtual memory 1396 space and the remaining part of the 4GB virtual memory space is used 1397 by the kernel to permanently map as much physical memory as 1398 possible. 1399 1400 If the machine has between 1 and 4 Gigabytes physical RAM, then 1401 answer "4GB" here. 1402 1403 If more than 4 Gigabytes is used then answer "64GB" here. This 1404 selection turns Intel PAE (Physical Address Extension) mode on. 1405 PAE implements 3-level paging on IA32 processors. PAE is fully 1406 supported by Linux, PAE mode is implemented on all recent Intel 1407 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1408 then the kernel will not boot on CPUs that don't support PAE! 1409 1410 The actual amount of total physical memory will either be 1411 auto detected or can be forced by using a kernel command line option 1412 such as "mem=256M". (Try "man bootparam" or see the documentation of 1413 your boot loader (lilo or loadlin) about how to pass options to the 1414 kernel at boot time.) 1415 1416 If unsure, say "off". 1417 1418config HIGHMEM4G 1419 bool "4GB" 1420 help 1421 Select this if you have a 32-bit processor and between 1 and 4 1422 gigabytes of physical RAM. 1423 1424config HIGHMEM64G 1425 bool "64GB" 1426 depends on X86_HAVE_PAE 1427 select X86_PAE 1428 help 1429 Select this if you have a 32-bit processor and more than 4 1430 gigabytes of physical RAM. 1431 1432endchoice 1433 1434choice 1435 prompt "Memory split" if EXPERT 1436 default VMSPLIT_3G 1437 depends on X86_32 1438 help 1439 Select the desired split between kernel and user memory. 1440 1441 If the address range available to the kernel is less than the 1442 physical memory installed, the remaining memory will be available 1443 as "high memory". Accessing high memory is a little more costly 1444 than low memory, as it needs to be mapped into the kernel first. 1445 Note that increasing the kernel address space limits the range 1446 available to user programs, making the address space there 1447 tighter. Selecting anything other than the default 3G/1G split 1448 will also likely make your kernel incompatible with binary-only 1449 kernel modules. 1450 1451 If you are not absolutely sure what you are doing, leave this 1452 option alone! 1453 1454 config VMSPLIT_3G 1455 bool "3G/1G user/kernel split" 1456 config VMSPLIT_3G_OPT 1457 depends on !X86_PAE 1458 bool "3G/1G user/kernel split (for full 1G low memory)" 1459 config VMSPLIT_2G 1460 bool "2G/2G user/kernel split" 1461 config VMSPLIT_2G_OPT 1462 depends on !X86_PAE 1463 bool "2G/2G user/kernel split (for full 2G low memory)" 1464 config VMSPLIT_1G 1465 bool "1G/3G user/kernel split" 1466endchoice 1467 1468config PAGE_OFFSET 1469 hex 1470 default 0xB0000000 if VMSPLIT_3G_OPT 1471 default 0x80000000 if VMSPLIT_2G 1472 default 0x78000000 if VMSPLIT_2G_OPT 1473 default 0x40000000 if VMSPLIT_1G 1474 default 0xC0000000 1475 depends on X86_32 1476 1477config HIGHMEM 1478 def_bool y 1479 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1480 1481config X86_PAE 1482 bool "PAE (Physical Address Extension) Support" 1483 depends on X86_32 && X86_HAVE_PAE 1484 select PHYS_ADDR_T_64BIT 1485 select SWIOTLB 1486 help 1487 PAE is required for NX support, and furthermore enables 1488 larger swapspace support for non-overcommit purposes. It 1489 has the cost of more pagetable lookup overhead, and also 1490 consumes more pagetable space per process. 1491 1492config X86_5LEVEL 1493 bool "Enable 5-level page tables support" 1494 default y 1495 select DYNAMIC_MEMORY_LAYOUT 1496 select SPARSEMEM_VMEMMAP 1497 depends on X86_64 1498 help 1499 5-level paging enables access to larger address space: 1500 up to 128 PiB of virtual address space and 4 PiB of 1501 physical address space. 1502 1503 It will be supported by future Intel CPUs. 1504 1505 A kernel with the option enabled can be booted on machines that 1506 support 4- or 5-level paging. 1507 1508 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1509 information. 1510 1511 Say N if unsure. 1512 1513config X86_DIRECT_GBPAGES 1514 def_bool y 1515 depends on X86_64 1516 help 1517 Certain kernel features effectively disable kernel 1518 linear 1 GB mappings (even if the CPU otherwise 1519 supports them), so don't confuse the user by printing 1520 that we have them enabled. 1521 1522config X86_CPA_STATISTICS 1523 bool "Enable statistic for Change Page Attribute" 1524 depends on DEBUG_FS 1525 help 1526 Expose statistics about the Change Page Attribute mechanism, which 1527 helps to determine the effectiveness of preserving large and huge 1528 page mappings when mapping protections are changed. 1529 1530config X86_MEM_ENCRYPT 1531 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1532 select DYNAMIC_PHYSICAL_MASK 1533 def_bool n 1534 1535config AMD_MEM_ENCRYPT 1536 bool "AMD Secure Memory Encryption (SME) support" 1537 depends on X86_64 && CPU_SUP_AMD 1538 depends on EFI_STUB 1539 select DMA_COHERENT_POOL 1540 select ARCH_USE_MEMREMAP_PROT 1541 select INSTRUCTION_DECODER 1542 select ARCH_HAS_CC_PLATFORM 1543 select X86_MEM_ENCRYPT 1544 select UNACCEPTED_MEMORY 1545 help 1546 Say yes to enable support for the encryption of system memory. 1547 This requires an AMD processor that supports Secure Memory 1548 Encryption (SME). 1549 1550# Common NUMA Features 1551config NUMA 1552 bool "NUMA Memory Allocation and Scheduler Support" 1553 depends on SMP 1554 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1555 default y if X86_BIGSMP 1556 select USE_PERCPU_NUMA_NODE_ID 1557 select OF_NUMA if OF 1558 help 1559 Enable NUMA (Non-Uniform Memory Access) support. 1560 1561 The kernel will try to allocate memory used by a CPU on the 1562 local memory controller of the CPU and add some more 1563 NUMA awareness to the kernel. 1564 1565 For 64-bit this is recommended if the system is Intel Core i7 1566 (or later), AMD Opteron, or EM64T NUMA. 1567 1568 For 32-bit this is only needed if you boot a 32-bit 1569 kernel on a 64-bit NUMA platform. 1570 1571 Otherwise, you should say N. 1572 1573config AMD_NUMA 1574 def_bool y 1575 prompt "Old style AMD Opteron NUMA detection" 1576 depends on X86_64 && NUMA && PCI 1577 help 1578 Enable AMD NUMA node topology detection. You should say Y here if 1579 you have a multi processor AMD system. This uses an old method to 1580 read the NUMA configuration directly from the builtin Northbridge 1581 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1582 which also takes priority if both are compiled in. 1583 1584config X86_64_ACPI_NUMA 1585 def_bool y 1586 prompt "ACPI NUMA detection" 1587 depends on X86_64 && NUMA && ACPI && PCI 1588 select ACPI_NUMA 1589 help 1590 Enable ACPI SRAT based node topology detection. 1591 1592config NUMA_EMU 1593 bool "NUMA emulation" 1594 depends on NUMA 1595 help 1596 Enable NUMA emulation. A flat machine will be split 1597 into virtual nodes when booted with "numa=fake=N", where N is the 1598 number of nodes. This is only useful for debugging. 1599 1600config NODES_SHIFT 1601 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1602 range 1 10 1603 default "10" if MAXSMP 1604 default "6" if X86_64 1605 default "3" 1606 depends on NUMA 1607 help 1608 Specify the maximum number of NUMA Nodes available on the target 1609 system. Increases memory reserved to accommodate various tables. 1610 1611config ARCH_FLATMEM_ENABLE 1612 def_bool y 1613 depends on X86_32 && !NUMA 1614 1615config ARCH_SPARSEMEM_ENABLE 1616 def_bool y 1617 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1618 select SPARSEMEM_STATIC if X86_32 1619 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1620 1621config ARCH_SPARSEMEM_DEFAULT 1622 def_bool X86_64 || (NUMA && X86_32) 1623 1624config ARCH_SELECT_MEMORY_MODEL 1625 def_bool y 1626 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1627 1628config ARCH_MEMORY_PROBE 1629 bool "Enable sysfs memory/probe interface" 1630 depends on MEMORY_HOTPLUG 1631 help 1632 This option enables a sysfs memory/probe interface for testing. 1633 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1634 If you are unsure how to answer this question, answer N. 1635 1636config ARCH_PROC_KCORE_TEXT 1637 def_bool y 1638 depends on X86_64 && PROC_KCORE 1639 1640config ILLEGAL_POINTER_VALUE 1641 hex 1642 default 0 if X86_32 1643 default 0xdead000000000000 if X86_64 1644 1645config X86_PMEM_LEGACY_DEVICE 1646 bool 1647 1648config X86_PMEM_LEGACY 1649 tristate "Support non-standard NVDIMMs and ADR protected memory" 1650 depends on PHYS_ADDR_T_64BIT 1651 depends on BLK_DEV 1652 select X86_PMEM_LEGACY_DEVICE 1653 select NUMA_KEEP_MEMINFO if NUMA 1654 select LIBNVDIMM 1655 help 1656 Treat memory marked using the non-standard e820 type of 12 as used 1657 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1658 The kernel will offer these regions to the 'pmem' driver so 1659 they can be used for persistent storage. 1660 1661 Say Y if unsure. 1662 1663config HIGHPTE 1664 bool "Allocate 3rd-level pagetables from highmem" 1665 depends on HIGHMEM 1666 help 1667 The VM uses one page table entry for each page of physical memory. 1668 For systems with a lot of RAM, this can be wasteful of precious 1669 low memory. Setting this option will put user-space page table 1670 entries in high memory. 1671 1672config X86_CHECK_BIOS_CORRUPTION 1673 bool "Check for low memory corruption" 1674 help 1675 Periodically check for memory corruption in low memory, which 1676 is suspected to be caused by BIOS. Even when enabled in the 1677 configuration, it is disabled at runtime. Enable it by 1678 setting "memory_corruption_check=1" on the kernel command 1679 line. By default it scans the low 64k of memory every 60 1680 seconds; see the memory_corruption_check_size and 1681 memory_corruption_check_period parameters in 1682 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1683 1684 When enabled with the default parameters, this option has 1685 almost no overhead, as it reserves a relatively small amount 1686 of memory and scans it infrequently. It both detects corruption 1687 and prevents it from affecting the running system. 1688 1689 It is, however, intended as a diagnostic tool; if repeatable 1690 BIOS-originated corruption always affects the same memory, 1691 you can use memmap= to prevent the kernel from using that 1692 memory. 1693 1694config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1695 bool "Set the default setting of memory_corruption_check" 1696 depends on X86_CHECK_BIOS_CORRUPTION 1697 default y 1698 help 1699 Set whether the default state of memory_corruption_check is 1700 on or off. 1701 1702config MATH_EMULATION 1703 bool 1704 depends on MODIFY_LDT_SYSCALL 1705 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1706 help 1707 Linux can emulate a math coprocessor (used for floating point 1708 operations) if you don't have one. 486DX and Pentium processors have 1709 a math coprocessor built in, 486SX and 386 do not, unless you added 1710 a 487DX or 387, respectively. (The messages during boot time can 1711 give you some hints here ["man dmesg"].) Everyone needs either a 1712 coprocessor or this emulation. 1713 1714 If you don't have a math coprocessor, you need to say Y here; if you 1715 say Y here even though you have a coprocessor, the coprocessor will 1716 be used nevertheless. (This behavior can be changed with the kernel 1717 command line option "no387", which comes handy if your coprocessor 1718 is broken. Try "man bootparam" or see the documentation of your boot 1719 loader (lilo or loadlin) about how to pass options to the kernel at 1720 boot time.) This means that it is a good idea to say Y here if you 1721 intend to use this kernel on different machines. 1722 1723 More information about the internals of the Linux math coprocessor 1724 emulation can be found in <file:arch/x86/math-emu/README>. 1725 1726 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1727 kernel, it won't hurt. 1728 1729config MTRR 1730 def_bool y 1731 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1732 help 1733 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1734 the Memory Type Range Registers (MTRRs) may be used to control 1735 processor access to memory ranges. This is most useful if you have 1736 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1737 allows bus write transfers to be combined into a larger transfer 1738 before bursting over the PCI/AGP bus. This can increase performance 1739 of image write operations 2.5 times or more. Saying Y here creates a 1740 /proc/mtrr file which may be used to manipulate your processor's 1741 MTRRs. Typically the X server should use this. 1742 1743 This code has a reasonably generic interface so that similar 1744 control registers on other processors can be easily supported 1745 as well: 1746 1747 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1748 Registers (ARRs) which provide a similar functionality to MTRRs. For 1749 these, the ARRs are used to emulate the MTRRs. 1750 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1751 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1752 write-combining. All of these processors are supported by this code 1753 and it makes sense to say Y here if you have one of them. 1754 1755 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1756 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1757 can lead to all sorts of problems, so it's good to say Y here. 1758 1759 You can safely say Y even if your machine doesn't have MTRRs, you'll 1760 just add about 9 KB to your kernel. 1761 1762 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1763 1764config MTRR_SANITIZER 1765 def_bool y 1766 prompt "MTRR cleanup support" 1767 depends on MTRR 1768 help 1769 Convert MTRR layout from continuous to discrete, so X drivers can 1770 add writeback entries. 1771 1772 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1773 The largest mtrr entry size for a continuous block can be set with 1774 mtrr_chunk_size. 1775 1776 If unsure, say Y. 1777 1778config MTRR_SANITIZER_ENABLE_DEFAULT 1779 int "MTRR cleanup enable value (0-1)" 1780 range 0 1 1781 default "0" 1782 depends on MTRR_SANITIZER 1783 help 1784 Enable mtrr cleanup default value 1785 1786config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1787 int "MTRR cleanup spare reg num (0-7)" 1788 range 0 7 1789 default "1" 1790 depends on MTRR_SANITIZER 1791 help 1792 mtrr cleanup spare entries default, it can be changed via 1793 mtrr_spare_reg_nr=N on the kernel command line. 1794 1795config X86_PAT 1796 def_bool y 1797 prompt "x86 PAT support" if EXPERT 1798 depends on MTRR 1799 help 1800 Use PAT attributes to setup page level cache control. 1801 1802 PATs are the modern equivalents of MTRRs and are much more 1803 flexible than MTRRs. 1804 1805 Say N here if you see bootup problems (boot crash, boot hang, 1806 spontaneous reboots) or a non-working video driver. 1807 1808 If unsure, say Y. 1809 1810config ARCH_USES_PG_UNCACHED 1811 def_bool y 1812 depends on X86_PAT 1813 1814config X86_UMIP 1815 def_bool y 1816 prompt "User Mode Instruction Prevention" if EXPERT 1817 help 1818 User Mode Instruction Prevention (UMIP) is a security feature in 1819 some x86 processors. If enabled, a general protection fault is 1820 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1821 executed in user mode. These instructions unnecessarily expose 1822 information about the hardware state. 1823 1824 The vast majority of applications do not use these instructions. 1825 For the very few that do, software emulation is provided in 1826 specific cases in protected and virtual-8086 modes. Emulated 1827 results are dummy. 1828 1829config CC_HAS_IBT 1830 # GCC >= 9 and binutils >= 2.29 1831 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1832 # Clang/LLVM >= 14 1833 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1834 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1835 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1836 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1837 $(as-instr,endbr64) 1838 1839config X86_CET 1840 def_bool n 1841 help 1842 CET features configured (Shadow stack or IBT) 1843 1844config X86_KERNEL_IBT 1845 prompt "Indirect Branch Tracking" 1846 def_bool y 1847 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1848 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1849 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1850 select OBJTOOL 1851 select X86_CET 1852 help 1853 Build the kernel with support for Indirect Branch Tracking, a 1854 hardware support course-grain forward-edge Control Flow Integrity 1855 protection. It enforces that all indirect calls must land on 1856 an ENDBR instruction, as such, the compiler will instrument the 1857 code with them to make this happen. 1858 1859 In addition to building the kernel with IBT, seal all functions that 1860 are not indirect call targets, avoiding them ever becoming one. 1861 1862 This requires LTO like objtool runs and will slow down the build. It 1863 does significantly reduce the number of ENDBR instructions in the 1864 kernel image. 1865 1866config X86_INTEL_MEMORY_PROTECTION_KEYS 1867 prompt "Memory Protection Keys" 1868 def_bool y 1869 # Note: only available in 64-bit mode 1870 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1871 select ARCH_USES_HIGH_VMA_FLAGS 1872 select ARCH_HAS_PKEYS 1873 help 1874 Memory Protection Keys provides a mechanism for enforcing 1875 page-based protections, but without requiring modification of the 1876 page tables when an application changes protection domains. 1877 1878 For details, see Documentation/core-api/protection-keys.rst 1879 1880 If unsure, say y. 1881 1882choice 1883 prompt "TSX enable mode" 1884 depends on CPU_SUP_INTEL 1885 default X86_INTEL_TSX_MODE_OFF 1886 help 1887 Intel's TSX (Transactional Synchronization Extensions) feature 1888 allows to optimize locking protocols through lock elision which 1889 can lead to a noticeable performance boost. 1890 1891 On the other hand it has been shown that TSX can be exploited 1892 to form side channel attacks (e.g. TAA) and chances are there 1893 will be more of those attacks discovered in the future. 1894 1895 Therefore TSX is not enabled by default (aka tsx=off). An admin 1896 might override this decision by tsx=on the command line parameter. 1897 Even with TSX enabled, the kernel will attempt to enable the best 1898 possible TAA mitigation setting depending on the microcode available 1899 for the particular machine. 1900 1901 This option allows to set the default tsx mode between tsx=on, =off 1902 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1903 details. 1904 1905 Say off if not sure, auto if TSX is in use but it should be used on safe 1906 platforms or on if TSX is in use and the security aspect of tsx is not 1907 relevant. 1908 1909config X86_INTEL_TSX_MODE_OFF 1910 bool "off" 1911 help 1912 TSX is disabled if possible - equals to tsx=off command line parameter. 1913 1914config X86_INTEL_TSX_MODE_ON 1915 bool "on" 1916 help 1917 TSX is always enabled on TSX capable HW - equals the tsx=on command 1918 line parameter. 1919 1920config X86_INTEL_TSX_MODE_AUTO 1921 bool "auto" 1922 help 1923 TSX is enabled on TSX capable HW that is believed to be safe against 1924 side channel attacks- equals the tsx=auto command line parameter. 1925endchoice 1926 1927config X86_SGX 1928 bool "Software Guard eXtensions (SGX)" 1929 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1930 depends on CRYPTO=y 1931 depends on CRYPTO_SHA256=y 1932 select MMU_NOTIFIER 1933 select NUMA_KEEP_MEMINFO if NUMA 1934 select XARRAY_MULTI 1935 help 1936 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1937 that can be used by applications to set aside private regions of code 1938 and data, referred to as enclaves. An enclave's private memory can 1939 only be accessed by code running within the enclave. Accesses from 1940 outside the enclave, including other enclaves, are disallowed by 1941 hardware. 1942 1943 If unsure, say N. 1944 1945config X86_USER_SHADOW_STACK 1946 bool "X86 userspace shadow stack" 1947 depends on AS_WRUSS 1948 depends on X86_64 1949 select ARCH_USES_HIGH_VMA_FLAGS 1950 select X86_CET 1951 help 1952 Shadow stack protection is a hardware feature that detects function 1953 return address corruption. This helps mitigate ROP attacks. 1954 Applications must be enabled to use it, and old userspace does not 1955 get protection "for free". 1956 1957 CPUs supporting shadow stacks were first released in 2020. 1958 1959 See Documentation/arch/x86/shstk.rst for more information. 1960 1961 If unsure, say N. 1962 1963config INTEL_TDX_HOST 1964 bool "Intel Trust Domain Extensions (TDX) host support" 1965 depends on CPU_SUP_INTEL 1966 depends on X86_64 1967 depends on KVM_INTEL 1968 depends on X86_X2APIC 1969 select ARCH_KEEP_MEMBLOCK 1970 depends on CONTIG_ALLOC 1971 depends on !KEXEC_CORE 1972 depends on X86_MCE 1973 help 1974 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1975 host and certain physical attacks. This option enables necessary TDX 1976 support in the host kernel to run confidential VMs. 1977 1978 If unsure, say N. 1979 1980config EFI 1981 bool "EFI runtime service support" 1982 depends on ACPI 1983 select UCS2_STRING 1984 select EFI_RUNTIME_WRAPPERS 1985 select ARCH_USE_MEMREMAP_PROT 1986 select EFI_RUNTIME_MAP if KEXEC_CORE 1987 help 1988 This enables the kernel to use EFI runtime services that are 1989 available (such as the EFI variable services). 1990 1991 This option is only useful on systems that have EFI firmware. 1992 In addition, you should use the latest ELILO loader available 1993 at <http://elilo.sourceforge.net> in order to take advantage 1994 of EFI runtime services. However, even with this option, the 1995 resultant kernel should continue to boot on existing non-EFI 1996 platforms. 1997 1998config EFI_STUB 1999 bool "EFI stub support" 2000 depends on EFI 2001 select RELOCATABLE 2002 help 2003 This kernel feature allows a bzImage to be loaded directly 2004 by EFI firmware without the use of a bootloader. 2005 2006 See Documentation/admin-guide/efi-stub.rst for more information. 2007 2008config EFI_HANDOVER_PROTOCOL 2009 bool "EFI handover protocol (DEPRECATED)" 2010 depends on EFI_STUB 2011 default y 2012 help 2013 Select this in order to include support for the deprecated EFI 2014 handover protocol, which defines alternative entry points into the 2015 EFI stub. This is a practice that has no basis in the UEFI 2016 specification, and requires a priori knowledge on the part of the 2017 bootloader about Linux/x86 specific ways of passing the command line 2018 and initrd, and where in memory those assets may be loaded. 2019 2020 If in doubt, say Y. Even though the corresponding support is not 2021 present in upstream GRUB or other bootloaders, most distros build 2022 GRUB with numerous downstream patches applied, and may rely on the 2023 handover protocol as as result. 2024 2025config EFI_MIXED 2026 bool "EFI mixed-mode support" 2027 depends on EFI_STUB && X86_64 2028 help 2029 Enabling this feature allows a 64-bit kernel to be booted 2030 on a 32-bit firmware, provided that your CPU supports 64-bit 2031 mode. 2032 2033 Note that it is not possible to boot a mixed-mode enabled 2034 kernel via the EFI boot stub - a bootloader that supports 2035 the EFI handover protocol must be used. 2036 2037 If unsure, say N. 2038 2039config EFI_FAKE_MEMMAP 2040 bool "Enable EFI fake memory map" 2041 depends on EFI 2042 help 2043 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2044 this parameter, you can add arbitrary attribute to specific memory 2045 range by updating original (firmware provided) EFI memmap. This is 2046 useful for debugging of EFI memmap related feature, e.g., Address 2047 Range Mirroring feature. 2048 2049config EFI_MAX_FAKE_MEM 2050 int "maximum allowable number of ranges in efi_fake_mem boot option" 2051 depends on EFI_FAKE_MEMMAP 2052 range 1 128 2053 default 8 2054 help 2055 Maximum allowable number of ranges in efi_fake_mem boot option. 2056 Ranges can be set up to this value using comma-separated list. 2057 The default value is 8. 2058 2059config EFI_RUNTIME_MAP 2060 bool "Export EFI runtime maps to sysfs" if EXPERT 2061 depends on EFI 2062 help 2063 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2064 That memory map is required by the 2nd kernel to set up EFI virtual 2065 mappings after kexec, but can also be used for debugging purposes. 2066 2067 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2068 2069source "kernel/Kconfig.hz" 2070 2071config ARCH_SUPPORTS_KEXEC 2072 def_bool y 2073 2074config ARCH_SUPPORTS_KEXEC_FILE 2075 def_bool X86_64 2076 2077config ARCH_SELECTS_KEXEC_FILE 2078 def_bool y 2079 depends on KEXEC_FILE 2080 select HAVE_IMA_KEXEC if IMA 2081 2082config ARCH_SUPPORTS_KEXEC_PURGATORY 2083 def_bool y 2084 2085config ARCH_SUPPORTS_KEXEC_SIG 2086 def_bool y 2087 2088config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2089 def_bool y 2090 2091config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2092 def_bool y 2093 2094config ARCH_SUPPORTS_KEXEC_JUMP 2095 def_bool y 2096 2097config ARCH_SUPPORTS_CRASH_DUMP 2098 def_bool X86_64 || (X86_32 && HIGHMEM) 2099 2100config ARCH_SUPPORTS_CRASH_HOTPLUG 2101 def_bool y 2102 2103config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2104 def_bool CRASH_RESERVE 2105 2106config PHYSICAL_START 2107 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2108 default "0x1000000" 2109 help 2110 This gives the physical address where the kernel is loaded. 2111 2112 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2113 will decompress itself to above physical address and run from there. 2114 Otherwise, bzImage will run from the address where it has been loaded 2115 by the boot loader. The only exception is if it is loaded below the 2116 above physical address, in which case it will relocate itself there. 2117 2118 In normal kdump cases one does not have to set/change this option 2119 as now bzImage can be compiled as a completely relocatable image 2120 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2121 address. This option is mainly useful for the folks who don't want 2122 to use a bzImage for capturing the crash dump and want to use a 2123 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2124 to be specifically compiled to run from a specific memory area 2125 (normally a reserved region) and this option comes handy. 2126 2127 So if you are using bzImage for capturing the crash dump, 2128 leave the value here unchanged to 0x1000000 and set 2129 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2130 for capturing the crash dump change this value to start of 2131 the reserved region. In other words, it can be set based on 2132 the "X" value as specified in the "crashkernel=YM@XM" 2133 command line boot parameter passed to the panic-ed 2134 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2135 for more details about crash dumps. 2136 2137 Usage of bzImage for capturing the crash dump is recommended as 2138 one does not have to build two kernels. Same kernel can be used 2139 as production kernel and capture kernel. Above option should have 2140 gone away after relocatable bzImage support is introduced. But it 2141 is present because there are users out there who continue to use 2142 vmlinux for dump capture. This option should go away down the 2143 line. 2144 2145 Don't change this unless you know what you are doing. 2146 2147config RELOCATABLE 2148 bool "Build a relocatable kernel" 2149 default y 2150 help 2151 This builds a kernel image that retains relocation information 2152 so it can be loaded someplace besides the default 1MB. 2153 The relocations tend to make the kernel binary about 10% larger, 2154 but are discarded at runtime. 2155 2156 One use is for the kexec on panic case where the recovery kernel 2157 must live at a different physical address than the primary 2158 kernel. 2159 2160 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2161 it has been loaded at and the compile time physical address 2162 (CONFIG_PHYSICAL_START) is used as the minimum location. 2163 2164config RANDOMIZE_BASE 2165 bool "Randomize the address of the kernel image (KASLR)" 2166 depends on RELOCATABLE 2167 default y 2168 help 2169 In support of Kernel Address Space Layout Randomization (KASLR), 2170 this randomizes the physical address at which the kernel image 2171 is decompressed and the virtual address where the kernel 2172 image is mapped, as a security feature that deters exploit 2173 attempts relying on knowledge of the location of kernel 2174 code internals. 2175 2176 On 64-bit, the kernel physical and virtual addresses are 2177 randomized separately. The physical address will be anywhere 2178 between 16MB and the top of physical memory (up to 64TB). The 2179 virtual address will be randomized from 16MB up to 1GB (9 bits 2180 of entropy). Note that this also reduces the memory space 2181 available to kernel modules from 1.5GB to 1GB. 2182 2183 On 32-bit, the kernel physical and virtual addresses are 2184 randomized together. They will be randomized from 16MB up to 2185 512MB (8 bits of entropy). 2186 2187 Entropy is generated using the RDRAND instruction if it is 2188 supported. If RDTSC is supported, its value is mixed into 2189 the entropy pool as well. If neither RDRAND nor RDTSC are 2190 supported, then entropy is read from the i8254 timer. The 2191 usable entropy is limited by the kernel being built using 2192 2GB addressing, and that PHYSICAL_ALIGN must be at a 2193 minimum of 2MB. As a result, only 10 bits of entropy are 2194 theoretically possible, but the implementations are further 2195 limited due to memory layouts. 2196 2197 If unsure, say Y. 2198 2199# Relocation on x86 needs some additional build support 2200config X86_NEED_RELOCS 2201 def_bool y 2202 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2203 2204config PHYSICAL_ALIGN 2205 hex "Alignment value to which kernel should be aligned" 2206 default "0x200000" 2207 range 0x2000 0x1000000 if X86_32 2208 range 0x200000 0x1000000 if X86_64 2209 help 2210 This value puts the alignment restrictions on physical address 2211 where kernel is loaded and run from. Kernel is compiled for an 2212 address which meets above alignment restriction. 2213 2214 If bootloader loads the kernel at a non-aligned address and 2215 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2216 address aligned to above value and run from there. 2217 2218 If bootloader loads the kernel at a non-aligned address and 2219 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2220 load address and decompress itself to the address it has been 2221 compiled for and run from there. The address for which kernel is 2222 compiled already meets above alignment restrictions. Hence the 2223 end result is that kernel runs from a physical address meeting 2224 above alignment restrictions. 2225 2226 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2227 this value must be a multiple of 0x200000. 2228 2229 Don't change this unless you know what you are doing. 2230 2231config DYNAMIC_MEMORY_LAYOUT 2232 bool 2233 help 2234 This option makes base addresses of vmalloc and vmemmap as well as 2235 __PAGE_OFFSET movable during boot. 2236 2237config RANDOMIZE_MEMORY 2238 bool "Randomize the kernel memory sections" 2239 depends on X86_64 2240 depends on RANDOMIZE_BASE 2241 select DYNAMIC_MEMORY_LAYOUT 2242 default RANDOMIZE_BASE 2243 help 2244 Randomizes the base virtual address of kernel memory sections 2245 (physical memory mapping, vmalloc & vmemmap). This security feature 2246 makes exploits relying on predictable memory locations less reliable. 2247 2248 The order of allocations remains unchanged. Entropy is generated in 2249 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2250 configuration have in average 30,000 different possible virtual 2251 addresses for each memory section. 2252 2253 If unsure, say Y. 2254 2255config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2256 hex "Physical memory mapping padding" if EXPERT 2257 depends on RANDOMIZE_MEMORY 2258 default "0xa" if MEMORY_HOTPLUG 2259 default "0x0" 2260 range 0x1 0x40 if MEMORY_HOTPLUG 2261 range 0x0 0x40 2262 help 2263 Define the padding in terabytes added to the existing physical 2264 memory size during kernel memory randomization. It is useful 2265 for memory hotplug support but reduces the entropy available for 2266 address randomization. 2267 2268 If unsure, leave at the default value. 2269 2270config ADDRESS_MASKING 2271 bool "Linear Address Masking support" 2272 depends on X86_64 2273 help 2274 Linear Address Masking (LAM) modifies the checking that is applied 2275 to 64-bit linear addresses, allowing software to use of the 2276 untranslated address bits for metadata. 2277 2278 The capability can be used for efficient address sanitizers (ASAN) 2279 implementation and for optimizations in JITs. 2280 2281config HOTPLUG_CPU 2282 def_bool y 2283 depends on SMP 2284 2285config COMPAT_VDSO 2286 def_bool n 2287 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2288 depends on COMPAT_32 2289 help 2290 Certain buggy versions of glibc will crash if they are 2291 presented with a 32-bit vDSO that is not mapped at the address 2292 indicated in its segment table. 2293 2294 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2295 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2296 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2297 the only released version with the bug, but OpenSUSE 9 2298 contains a buggy "glibc 2.3.2". 2299 2300 The symptom of the bug is that everything crashes on startup, saying: 2301 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2302 2303 Saying Y here changes the default value of the vdso32 boot 2304 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2305 This works around the glibc bug but hurts performance. 2306 2307 If unsure, say N: if you are compiling your own kernel, you 2308 are unlikely to be using a buggy version of glibc. 2309 2310choice 2311 prompt "vsyscall table for legacy applications" 2312 depends on X86_64 2313 default LEGACY_VSYSCALL_XONLY 2314 help 2315 Legacy user code that does not know how to find the vDSO expects 2316 to be able to issue three syscalls by calling fixed addresses in 2317 kernel space. Since this location is not randomized with ASLR, 2318 it can be used to assist security vulnerability exploitation. 2319 2320 This setting can be changed at boot time via the kernel command 2321 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2322 is deprecated and can only be enabled using the kernel command 2323 line. 2324 2325 On a system with recent enough glibc (2.14 or newer) and no 2326 static binaries, you can say None without a performance penalty 2327 to improve security. 2328 2329 If unsure, select "Emulate execution only". 2330 2331 config LEGACY_VSYSCALL_XONLY 2332 bool "Emulate execution only" 2333 help 2334 The kernel traps and emulates calls into the fixed vsyscall 2335 address mapping and does not allow reads. This 2336 configuration is recommended when userspace might use the 2337 legacy vsyscall area but support for legacy binary 2338 instrumentation of legacy code is not needed. It mitigates 2339 certain uses of the vsyscall area as an ASLR-bypassing 2340 buffer. 2341 2342 config LEGACY_VSYSCALL_NONE 2343 bool "None" 2344 help 2345 There will be no vsyscall mapping at all. This will 2346 eliminate any risk of ASLR bypass due to the vsyscall 2347 fixed address mapping. Attempts to use the vsyscalls 2348 will be reported to dmesg, so that either old or 2349 malicious userspace programs can be identified. 2350 2351endchoice 2352 2353config CMDLINE_BOOL 2354 bool "Built-in kernel command line" 2355 help 2356 Allow for specifying boot arguments to the kernel at 2357 build time. On some systems (e.g. embedded ones), it is 2358 necessary or convenient to provide some or all of the 2359 kernel boot arguments with the kernel itself (that is, 2360 to not rely on the boot loader to provide them.) 2361 2362 To compile command line arguments into the kernel, 2363 set this option to 'Y', then fill in the 2364 boot arguments in CONFIG_CMDLINE. 2365 2366 Systems with fully functional boot loaders (i.e. non-embedded) 2367 should leave this option set to 'N'. 2368 2369config CMDLINE 2370 string "Built-in kernel command string" 2371 depends on CMDLINE_BOOL 2372 default "" 2373 help 2374 Enter arguments here that should be compiled into the kernel 2375 image and used at boot time. If the boot loader provides a 2376 command line at boot time, it is appended to this string to 2377 form the full kernel command line, when the system boots. 2378 2379 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2380 change this behavior. 2381 2382 In most cases, the command line (whether built-in or provided 2383 by the boot loader) should specify the device for the root 2384 file system. 2385 2386config CMDLINE_OVERRIDE 2387 bool "Built-in command line overrides boot loader arguments" 2388 depends on CMDLINE_BOOL && CMDLINE != "" 2389 help 2390 Set this option to 'Y' to have the kernel ignore the boot loader 2391 command line, and use ONLY the built-in command line. 2392 2393 This is used to work around broken boot loaders. This should 2394 be set to 'N' under normal conditions. 2395 2396config MODIFY_LDT_SYSCALL 2397 bool "Enable the LDT (local descriptor table)" if EXPERT 2398 default y 2399 help 2400 Linux can allow user programs to install a per-process x86 2401 Local Descriptor Table (LDT) using the modify_ldt(2) system 2402 call. This is required to run 16-bit or segmented code such as 2403 DOSEMU or some Wine programs. It is also used by some very old 2404 threading libraries. 2405 2406 Enabling this feature adds a small amount of overhead to 2407 context switches and increases the low-level kernel attack 2408 surface. Disabling it removes the modify_ldt(2) system call. 2409 2410 Saying 'N' here may make sense for embedded or server kernels. 2411 2412config STRICT_SIGALTSTACK_SIZE 2413 bool "Enforce strict size checking for sigaltstack" 2414 depends on DYNAMIC_SIGFRAME 2415 help 2416 For historical reasons MINSIGSTKSZ is a constant which became 2417 already too small with AVX512 support. Add a mechanism to 2418 enforce strict checking of the sigaltstack size against the 2419 real size of the FPU frame. This option enables the check 2420 by default. It can also be controlled via the kernel command 2421 line option 'strict_sas_size' independent of this config 2422 switch. Enabling it might break existing applications which 2423 allocate a too small sigaltstack but 'work' because they 2424 never get a signal delivered. 2425 2426 Say 'N' unless you want to really enforce this check. 2427 2428source "kernel/livepatch/Kconfig" 2429 2430endmenu 2431 2432config CC_HAS_NAMED_AS 2433 def_bool CC_IS_GCC && GCC_VERSION >= 120100 2434 2435config USE_X86_SEG_SUPPORT 2436 def_bool y 2437 depends on CC_HAS_NAMED_AS 2438 # 2439 # -fsanitize=kernel-address (KASAN) is at the moment incompatible 2440 # with named address spaces - see GCC PR sanitizer/111736. 2441 # 2442 depends on !KASAN 2443 # -fsanitize=thread (KCSAN) is also incompatible. 2444 depends on !KCSAN 2445 2446config CC_HAS_SLS 2447 def_bool $(cc-option,-mharden-sls=all) 2448 2449config CC_HAS_RETURN_THUNK 2450 def_bool $(cc-option,-mfunction-return=thunk-extern) 2451 2452config CC_HAS_ENTRY_PADDING 2453 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2454 2455config FUNCTION_PADDING_CFI 2456 int 2457 default 59 if FUNCTION_ALIGNMENT_64B 2458 default 27 if FUNCTION_ALIGNMENT_32B 2459 default 11 if FUNCTION_ALIGNMENT_16B 2460 default 3 if FUNCTION_ALIGNMENT_8B 2461 default 0 2462 2463# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2464# except Kconfig can't do arithmetic :/ 2465config FUNCTION_PADDING_BYTES 2466 int 2467 default FUNCTION_PADDING_CFI if CFI_CLANG 2468 default FUNCTION_ALIGNMENT 2469 2470config CALL_PADDING 2471 def_bool n 2472 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2473 select FUNCTION_ALIGNMENT_16B 2474 2475config FINEIBT 2476 def_bool y 2477 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE 2478 select CALL_PADDING 2479 2480config HAVE_CALL_THUNKS 2481 def_bool y 2482 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2483 2484config CALL_THUNKS 2485 def_bool n 2486 select CALL_PADDING 2487 2488config PREFIX_SYMBOLS 2489 def_bool y 2490 depends on CALL_PADDING && !CFI_CLANG 2491 2492menuconfig CPU_MITIGATIONS 2493 bool "Mitigations for CPU vulnerabilities" 2494 default y 2495 help 2496 Say Y here to enable options which enable mitigations for hardware 2497 vulnerabilities (usually related to speculative execution). 2498 Mitigations can be disabled or restricted to SMT systems at runtime 2499 via the "mitigations" kernel parameter. 2500 2501 If you say N, all mitigations will be disabled. This CANNOT be 2502 overridden at runtime. 2503 2504 Say 'Y', unless you really know what you are doing. 2505 2506if CPU_MITIGATIONS 2507 2508config MITIGATION_PAGE_TABLE_ISOLATION 2509 bool "Remove the kernel mapping in user mode" 2510 default y 2511 depends on (X86_64 || X86_PAE) 2512 help 2513 This feature reduces the number of hardware side channels by 2514 ensuring that the majority of kernel addresses are not mapped 2515 into userspace. 2516 2517 See Documentation/arch/x86/pti.rst for more details. 2518 2519config MITIGATION_RETPOLINE 2520 bool "Avoid speculative indirect branches in kernel" 2521 select OBJTOOL if HAVE_OBJTOOL 2522 default y 2523 help 2524 Compile kernel with the retpoline compiler options to guard against 2525 kernel-to-user data leaks by avoiding speculative indirect 2526 branches. Requires a compiler with -mindirect-branch=thunk-extern 2527 support for full protection. The kernel may run slower. 2528 2529config MITIGATION_RETHUNK 2530 bool "Enable return-thunks" 2531 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2532 select OBJTOOL if HAVE_OBJTOOL 2533 default y if X86_64 2534 help 2535 Compile the kernel with the return-thunks compiler option to guard 2536 against kernel-to-user data leaks by avoiding return speculation. 2537 Requires a compiler with -mfunction-return=thunk-extern 2538 support for full protection. The kernel may run slower. 2539 2540config MITIGATION_UNRET_ENTRY 2541 bool "Enable UNRET on kernel entry" 2542 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2543 default y 2544 help 2545 Compile the kernel with support for the retbleed=unret mitigation. 2546 2547config MITIGATION_CALL_DEPTH_TRACKING 2548 bool "Mitigate RSB underflow with call depth tracking" 2549 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2550 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2551 select CALL_THUNKS 2552 default y 2553 help 2554 Compile the kernel with call depth tracking to mitigate the Intel 2555 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2556 mitigation is off by default and needs to be enabled on the 2557 kernel command line via the retbleed=stuff option. For 2558 non-affected systems the overhead of this option is marginal as 2559 the call depth tracking is using run-time generated call thunks 2560 in a compiler generated padding area and call patching. This 2561 increases text size by ~5%. For non affected systems this space 2562 is unused. On affected SKL systems this results in a significant 2563 performance gain over the IBRS mitigation. 2564 2565config CALL_THUNKS_DEBUG 2566 bool "Enable call thunks and call depth tracking debugging" 2567 depends on MITIGATION_CALL_DEPTH_TRACKING 2568 select FUNCTION_ALIGNMENT_32B 2569 default n 2570 help 2571 Enable call/ret counters for imbalance detection and build in 2572 a noisy dmesg about callthunks generation and call patching for 2573 trouble shooting. The debug prints need to be enabled on the 2574 kernel command line with 'debug-callthunks'. 2575 Only enable this when you are debugging call thunks as this 2576 creates a noticeable runtime overhead. If unsure say N. 2577 2578config MITIGATION_IBPB_ENTRY 2579 bool "Enable IBPB on kernel entry" 2580 depends on CPU_SUP_AMD && X86_64 2581 default y 2582 help 2583 Compile the kernel with support for the retbleed=ibpb mitigation. 2584 2585config MITIGATION_IBRS_ENTRY 2586 bool "Enable IBRS on kernel entry" 2587 depends on CPU_SUP_INTEL && X86_64 2588 default y 2589 help 2590 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2591 This mitigates both spectre_v2 and retbleed at great cost to 2592 performance. 2593 2594config MITIGATION_SRSO 2595 bool "Mitigate speculative RAS overflow on AMD" 2596 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2597 default y 2598 help 2599 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2600 2601config MITIGATION_SLS 2602 bool "Mitigate Straight-Line-Speculation" 2603 depends on CC_HAS_SLS && X86_64 2604 select OBJTOOL if HAVE_OBJTOOL 2605 default n 2606 help 2607 Compile the kernel with straight-line-speculation options to guard 2608 against straight line speculation. The kernel image might be slightly 2609 larger. 2610 2611config MITIGATION_GDS_FORCE 2612 bool "Force GDS Mitigation" 2613 depends on CPU_SUP_INTEL 2614 default n 2615 help 2616 Gather Data Sampling (GDS) is a hardware vulnerability which allows 2617 unprivileged speculative access to data which was previously stored in 2618 vector registers. 2619 2620 This option is equivalent to setting gather_data_sampling=force on the 2621 command line. The microcode mitigation is used if present, otherwise 2622 AVX is disabled as a mitigation. On affected systems that are missing 2623 the microcode any userspace code that unconditionally uses AVX will 2624 break with this option set. 2625 2626 Setting this option on systems not vulnerable to GDS has no effect. 2627 2628 If in doubt, say N. 2629 2630config MITIGATION_RFDS 2631 bool "RFDS Mitigation" 2632 depends on CPU_SUP_INTEL 2633 default y 2634 help 2635 Enable mitigation for Register File Data Sampling (RFDS) by default. 2636 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2637 allows unprivileged speculative access to stale data previously 2638 stored in floating point, vector and integer registers. 2639 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2640 2641config MITIGATION_SPECTRE_BHI 2642 bool "Mitigate Spectre-BHB (Branch History Injection)" 2643 depends on CPU_SUP_INTEL 2644 default y 2645 help 2646 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2647 where the branch history buffer is poisoned to speculatively steer 2648 indirect branches. 2649 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2650 2651endif 2652 2653config ARCH_HAS_ADD_PAGES 2654 def_bool y 2655 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2656 2657menu "Power management and ACPI options" 2658 2659config ARCH_HIBERNATION_HEADER 2660 def_bool y 2661 depends on HIBERNATION 2662 2663source "kernel/power/Kconfig" 2664 2665source "drivers/acpi/Kconfig" 2666 2667config X86_APM_BOOT 2668 def_bool y 2669 depends on APM 2670 2671menuconfig APM 2672 tristate "APM (Advanced Power Management) BIOS support" 2673 depends on X86_32 && PM_SLEEP 2674 help 2675 APM is a BIOS specification for saving power using several different 2676 techniques. This is mostly useful for battery powered laptops with 2677 APM compliant BIOSes. If you say Y here, the system time will be 2678 reset after a RESUME operation, the /proc/apm device will provide 2679 battery status information, and user-space programs will receive 2680 notification of APM "events" (e.g. battery status change). 2681 2682 If you select "Y" here, you can disable actual use of the APM 2683 BIOS by passing the "apm=off" option to the kernel at boot time. 2684 2685 Note that the APM support is almost completely disabled for 2686 machines with more than one CPU. 2687 2688 In order to use APM, you will need supporting software. For location 2689 and more information, read <file:Documentation/power/apm-acpi.rst> 2690 and the Battery Powered Linux mini-HOWTO, available from 2691 <http://www.tldp.org/docs.html#howto>. 2692 2693 This driver does not spin down disk drives (see the hdparm(8) 2694 manpage ("man 8 hdparm") for that), and it doesn't turn off 2695 VESA-compliant "green" monitors. 2696 2697 This driver does not support the TI 4000M TravelMate and the ACER 2698 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2699 desktop machines also don't have compliant BIOSes, and this driver 2700 may cause those machines to panic during the boot phase. 2701 2702 Generally, if you don't have a battery in your machine, there isn't 2703 much point in using this driver and you should say N. If you get 2704 random kernel OOPSes or reboots that don't seem to be related to 2705 anything, try disabling/enabling this option (or disabling/enabling 2706 APM in your BIOS). 2707 2708 Some other things you should try when experiencing seemingly random, 2709 "weird" problems: 2710 2711 1) make sure that you have enough swap space and that it is 2712 enabled. 2713 2) pass the "idle=poll" option to the kernel 2714 3) switch on floating point emulation in the kernel and pass 2715 the "no387" option to the kernel 2716 4) pass the "floppy=nodma" option to the kernel 2717 5) pass the "mem=4M" option to the kernel (thereby disabling 2718 all but the first 4 MB of RAM) 2719 6) make sure that the CPU is not over clocked. 2720 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2721 8) disable the cache from your BIOS settings 2722 9) install a fan for the video card or exchange video RAM 2723 10) install a better fan for the CPU 2724 11) exchange RAM chips 2725 12) exchange the motherboard. 2726 2727 To compile this driver as a module, choose M here: the 2728 module will be called apm. 2729 2730if APM 2731 2732config APM_IGNORE_USER_SUSPEND 2733 bool "Ignore USER SUSPEND" 2734 help 2735 This option will ignore USER SUSPEND requests. On machines with a 2736 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2737 series notebooks, it is necessary to say Y because of a BIOS bug. 2738 2739config APM_DO_ENABLE 2740 bool "Enable PM at boot time" 2741 help 2742 Enable APM features at boot time. From page 36 of the APM BIOS 2743 specification: "When disabled, the APM BIOS does not automatically 2744 power manage devices, enter the Standby State, enter the Suspend 2745 State, or take power saving steps in response to CPU Idle calls." 2746 This driver will make CPU Idle calls when Linux is idle (unless this 2747 feature is turned off -- see "Do CPU IDLE calls", below). This 2748 should always save battery power, but more complicated APM features 2749 will be dependent on your BIOS implementation. You may need to turn 2750 this option off if your computer hangs at boot time when using APM 2751 support, or if it beeps continuously instead of suspending. Turn 2752 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2753 T400CDT. This is off by default since most machines do fine without 2754 this feature. 2755 2756config APM_CPU_IDLE 2757 depends on CPU_IDLE 2758 bool "Make CPU Idle calls when idle" 2759 help 2760 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2761 On some machines, this can activate improved power savings, such as 2762 a slowed CPU clock rate, when the machine is idle. These idle calls 2763 are made after the idle loop has run for some length of time (e.g., 2764 333 mS). On some machines, this will cause a hang at boot time or 2765 whenever the CPU becomes idle. (On machines with more than one CPU, 2766 this option does nothing.) 2767 2768config APM_DISPLAY_BLANK 2769 bool "Enable console blanking using APM" 2770 help 2771 Enable console blanking using the APM. Some laptops can use this to 2772 turn off the LCD backlight when the screen blanker of the Linux 2773 virtual console blanks the screen. Note that this is only used by 2774 the virtual console screen blanker, and won't turn off the backlight 2775 when using the X Window system. This also doesn't have anything to 2776 do with your VESA-compliant power-saving monitor. Further, this 2777 option doesn't work for all laptops -- it might not turn off your 2778 backlight at all, or it might print a lot of errors to the console, 2779 especially if you are using gpm. 2780 2781config APM_ALLOW_INTS 2782 bool "Allow interrupts during APM BIOS calls" 2783 help 2784 Normally we disable external interrupts while we are making calls to 2785 the APM BIOS as a measure to lessen the effects of a badly behaving 2786 BIOS implementation. The BIOS should reenable interrupts if it 2787 needs to. Unfortunately, some BIOSes do not -- especially those in 2788 many of the newer IBM Thinkpads. If you experience hangs when you 2789 suspend, try setting this to Y. Otherwise, say N. 2790 2791endif # APM 2792 2793source "drivers/cpufreq/Kconfig" 2794 2795source "drivers/cpuidle/Kconfig" 2796 2797source "drivers/idle/Kconfig" 2798 2799endmenu 2800 2801menu "Bus options (PCI etc.)" 2802 2803choice 2804 prompt "PCI access mode" 2805 depends on X86_32 && PCI 2806 default PCI_GOANY 2807 help 2808 On PCI systems, the BIOS can be used to detect the PCI devices and 2809 determine their configuration. However, some old PCI motherboards 2810 have BIOS bugs and may crash if this is done. Also, some embedded 2811 PCI-based systems don't have any BIOS at all. Linux can also try to 2812 detect the PCI hardware directly without using the BIOS. 2813 2814 With this option, you can specify how Linux should detect the 2815 PCI devices. If you choose "BIOS", the BIOS will be used, 2816 if you choose "Direct", the BIOS won't be used, and if you 2817 choose "MMConfig", then PCI Express MMCONFIG will be used. 2818 If you choose "Any", the kernel will try MMCONFIG, then the 2819 direct access method and falls back to the BIOS if that doesn't 2820 work. If unsure, go with the default, which is "Any". 2821 2822config PCI_GOBIOS 2823 bool "BIOS" 2824 2825config PCI_GOMMCONFIG 2826 bool "MMConfig" 2827 2828config PCI_GODIRECT 2829 bool "Direct" 2830 2831config PCI_GOOLPC 2832 bool "OLPC XO-1" 2833 depends on OLPC 2834 2835config PCI_GOANY 2836 bool "Any" 2837 2838endchoice 2839 2840config PCI_BIOS 2841 def_bool y 2842 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2843 2844# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2845config PCI_DIRECT 2846 def_bool y 2847 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2848 2849config PCI_MMCONFIG 2850 bool "Support mmconfig PCI config space access" if X86_64 2851 default y 2852 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2853 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2854 2855config PCI_OLPC 2856 def_bool y 2857 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2858 2859config PCI_XEN 2860 def_bool y 2861 depends on PCI && XEN 2862 2863config MMCONF_FAM10H 2864 def_bool y 2865 depends on X86_64 && PCI_MMCONFIG && ACPI 2866 2867config PCI_CNB20LE_QUIRK 2868 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2869 depends on PCI 2870 help 2871 Read the PCI windows out of the CNB20LE host bridge. This allows 2872 PCI hotplug to work on systems with the CNB20LE chipset which do 2873 not have ACPI. 2874 2875 There's no public spec for this chipset, and this functionality 2876 is known to be incomplete. 2877 2878 You should say N unless you know you need this. 2879 2880config ISA_BUS 2881 bool "ISA bus support on modern systems" if EXPERT 2882 help 2883 Expose ISA bus device drivers and options available for selection and 2884 configuration. Enable this option if your target machine has an ISA 2885 bus. ISA is an older system, displaced by PCI and newer bus 2886 architectures -- if your target machine is modern, it probably does 2887 not have an ISA bus. 2888 2889 If unsure, say N. 2890 2891# x86_64 have no ISA slots, but can have ISA-style DMA. 2892config ISA_DMA_API 2893 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2894 default y 2895 help 2896 Enables ISA-style DMA support for devices requiring such controllers. 2897 If unsure, say Y. 2898 2899if X86_32 2900 2901config ISA 2902 bool "ISA support" 2903 help 2904 Find out whether you have ISA slots on your motherboard. ISA is the 2905 name of a bus system, i.e. the way the CPU talks to the other stuff 2906 inside your box. Other bus systems are PCI, EISA, MicroChannel 2907 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2908 newer boards don't support it. If you have ISA, say Y, otherwise N. 2909 2910config SCx200 2911 tristate "NatSemi SCx200 support" 2912 help 2913 This provides basic support for National Semiconductor's 2914 (now AMD's) Geode processors. The driver probes for the 2915 PCI-IDs of several on-chip devices, so its a good dependency 2916 for other scx200_* drivers. 2917 2918 If compiled as a module, the driver is named scx200. 2919 2920config SCx200HR_TIMER 2921 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2922 depends on SCx200 2923 default y 2924 help 2925 This driver provides a clocksource built upon the on-chip 2926 27MHz high-resolution timer. Its also a workaround for 2927 NSC Geode SC-1100's buggy TSC, which loses time when the 2928 processor goes idle (as is done by the scheduler). The 2929 other workaround is idle=poll boot option. 2930 2931config OLPC 2932 bool "One Laptop Per Child support" 2933 depends on !X86_PAE 2934 select GPIOLIB 2935 select OF 2936 select OF_PROMTREE 2937 select IRQ_DOMAIN 2938 select OLPC_EC 2939 help 2940 Add support for detecting the unique features of the OLPC 2941 XO hardware. 2942 2943config OLPC_XO1_PM 2944 bool "OLPC XO-1 Power Management" 2945 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2946 help 2947 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2948 2949config OLPC_XO1_RTC 2950 bool "OLPC XO-1 Real Time Clock" 2951 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2952 help 2953 Add support for the XO-1 real time clock, which can be used as a 2954 programmable wakeup source. 2955 2956config OLPC_XO1_SCI 2957 bool "OLPC XO-1 SCI extras" 2958 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2959 depends on INPUT=y 2960 select POWER_SUPPLY 2961 help 2962 Add support for SCI-based features of the OLPC XO-1 laptop: 2963 - EC-driven system wakeups 2964 - Power button 2965 - Ebook switch 2966 - Lid switch 2967 - AC adapter status updates 2968 - Battery status updates 2969 2970config OLPC_XO15_SCI 2971 bool "OLPC XO-1.5 SCI extras" 2972 depends on OLPC && ACPI 2973 select POWER_SUPPLY 2974 help 2975 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2976 - EC-driven system wakeups 2977 - AC adapter status updates 2978 - Battery status updates 2979 2980config ALIX 2981 bool "PCEngines ALIX System Support (LED setup)" 2982 select GPIOLIB 2983 help 2984 This option enables system support for the PCEngines ALIX. 2985 At present this just sets up LEDs for GPIO control on 2986 ALIX2/3/6 boards. However, other system specific setup should 2987 get added here. 2988 2989 Note: You must still enable the drivers for GPIO and LED support 2990 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2991 2992 Note: You have to set alix.force=1 for boards with Award BIOS. 2993 2994config NET5501 2995 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2996 select GPIOLIB 2997 help 2998 This option enables system support for the Soekris Engineering net5501. 2999 3000config GEOS 3001 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3002 select GPIOLIB 3003 depends on DMI 3004 help 3005 This option enables system support for the Traverse Technologies GEOS. 3006 3007config TS5500 3008 bool "Technologic Systems TS-5500 platform support" 3009 depends on MELAN 3010 select CHECK_SIGNATURE 3011 select NEW_LEDS 3012 select LEDS_CLASS 3013 help 3014 This option enables system support for the Technologic Systems TS-5500. 3015 3016endif # X86_32 3017 3018config AMD_NB 3019 def_bool y 3020 depends on CPU_SUP_AMD && PCI 3021 3022endmenu 3023 3024menu "Binary Emulations" 3025 3026config IA32_EMULATION 3027 bool "IA32 Emulation" 3028 depends on X86_64 3029 select ARCH_WANT_OLD_COMPAT_IPC 3030 select BINFMT_ELF 3031 select COMPAT_OLD_SIGACTION 3032 help 3033 Include code to run legacy 32-bit programs under a 3034 64-bit kernel. You should likely turn this on, unless you're 3035 100% sure that you don't have any 32-bit programs left. 3036 3037config IA32_EMULATION_DEFAULT_DISABLED 3038 bool "IA32 emulation disabled by default" 3039 default n 3040 depends on IA32_EMULATION 3041 help 3042 Make IA32 emulation disabled by default. This prevents loading 32-bit 3043 processes and access to 32-bit syscalls. If unsure, leave it to its 3044 default value. 3045 3046config X86_X32_ABI 3047 bool "x32 ABI for 64-bit mode" 3048 depends on X86_64 3049 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3050 # compressed debug sections to x86_x32 properly: 3051 # https://github.com/ClangBuiltLinux/linux/issues/514 3052 # https://github.com/ClangBuiltLinux/linux/issues/1141 3053 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3054 help 3055 Include code to run binaries for the x32 native 32-bit ABI 3056 for 64-bit processors. An x32 process gets access to the 3057 full 64-bit register file and wide data path while leaving 3058 pointers at 32 bits for smaller memory footprint. 3059 3060config COMPAT_32 3061 def_bool y 3062 depends on IA32_EMULATION || X86_32 3063 select HAVE_UID16 3064 select OLD_SIGSUSPEND3 3065 3066config COMPAT 3067 def_bool y 3068 depends on IA32_EMULATION || X86_X32_ABI 3069 3070config COMPAT_FOR_U64_ALIGNMENT 3071 def_bool y 3072 depends on COMPAT 3073 3074endmenu 3075 3076config HAVE_ATOMIC_IOMAP 3077 def_bool y 3078 depends on X86_32 3079 3080source "arch/x86/kvm/Kconfig" 3081 3082source "arch/x86/Kconfig.assembler" 3083