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 select EXECMEM if DYNAMIC_FTRACE 38 39config FORCE_DYNAMIC_FTRACE 40 def_bool y 41 depends on X86_32 42 depends on FUNCTION_TRACER 43 select DYNAMIC_FTRACE 44 help 45 We keep the static function tracing (!DYNAMIC_FTRACE) around 46 in order to test the non static function tracing in the 47 generic code, as other architectures still use it. But we 48 only need to keep it around for x86_64. No need to keep it 49 for x86_32. For x86_32, force DYNAMIC_FTRACE. 50# 51# Arch settings 52# 53# ( Note that options that are marked 'if X86_64' could in principle be 54# ported to 32-bit as well. ) 55# 56config X86 57 def_bool y 58 # 59 # Note: keep this list sorted alphabetically 60 # 61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 63 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 64 select ARCH_32BIT_OFF_T if X86_32 65 select ARCH_CLOCKSOURCE_INIT 66 select ARCH_CONFIGURES_CPU_MITIGATIONS 67 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 68 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 69 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 70 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 71 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 72 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 73 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 74 select ARCH_HAS_CACHE_LINE_SIZE 75 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 76 select ARCH_HAS_CPU_FINALIZE_INIT 77 select ARCH_HAS_CPU_PASID if IOMMU_SVA 78 select ARCH_HAS_CURRENT_STACK_POINTER 79 select ARCH_HAS_DEBUG_VIRTUAL 80 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 81 select ARCH_HAS_DEVMEM_IS_ALLOWED 82 select ARCH_HAS_EARLY_DEBUG if KGDB 83 select ARCH_HAS_ELF_RANDOMIZE 84 select ARCH_HAS_FAST_MULTIPLIER 85 select ARCH_HAS_FORTIFY_SOURCE 86 select ARCH_HAS_GCOV_PROFILE_ALL 87 select ARCH_HAS_KCOV if X86_64 88 select ARCH_HAS_KERNEL_FPU_SUPPORT 89 select ARCH_HAS_MEM_ENCRYPT 90 select ARCH_HAS_MEMBARRIER_SYNC_CORE 91 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 92 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 93 select ARCH_HAS_PMEM_API if X86_64 94 select ARCH_HAS_PTE_DEVMAP if X86_64 95 select ARCH_HAS_PTE_SPECIAL 96 select ARCH_HAS_HW_PTE_YOUNG 97 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 98 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 99 select ARCH_HAS_COPY_MC if X86_64 100 select ARCH_HAS_SET_MEMORY 101 select ARCH_HAS_SET_DIRECT_MAP 102 select ARCH_HAS_STRICT_KERNEL_RWX 103 select ARCH_HAS_STRICT_MODULE_RWX 104 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 105 select ARCH_HAS_SYSCALL_WRAPPER 106 select ARCH_HAS_UBSAN 107 select ARCH_HAS_DEBUG_WX 108 select ARCH_HAS_ZONE_DMA_SET if EXPERT 109 select ARCH_HAVE_NMI_SAFE_CMPXCHG 110 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 111 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 112 select ARCH_MIGHT_HAVE_PC_PARPORT 113 select ARCH_MIGHT_HAVE_PC_SERIO 114 select ARCH_STACKWALK 115 select ARCH_SUPPORTS_ACPI 116 select ARCH_SUPPORTS_ATOMIC_RMW 117 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 118 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 119 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 120 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 121 select ARCH_SUPPORTS_CFI_CLANG if X86_64 122 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 123 select ARCH_SUPPORTS_LTO_CLANG 124 select ARCH_SUPPORTS_LTO_CLANG_THIN 125 select ARCH_USE_BUILTIN_BSWAP 126 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64 127 select ARCH_USE_MEMTEST 128 select ARCH_USE_QUEUED_RWLOCKS 129 select ARCH_USE_QUEUED_SPINLOCKS 130 select ARCH_USE_SYM_ANNOTATIONS 131 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 132 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 133 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 134 select ARCH_WANTS_NO_INSTR 135 select ARCH_WANT_GENERAL_HUGETLB 136 select ARCH_WANT_HUGE_PMD_SHARE 137 select ARCH_WANT_LD_ORPHAN_WARN 138 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 139 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 140 select ARCH_WANTS_THP_SWAP if X86_64 141 select ARCH_HAS_PARANOID_L1D_FLUSH 142 select BUILDTIME_TABLE_SORT 143 select CLKEVT_I8253 144 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 145 select CLOCKSOURCE_WATCHDOG 146 # Word-size accesses may read uninitialized data past the trailing \0 147 # in strings and cause false KMSAN reports. 148 select DCACHE_WORD_ACCESS if !KMSAN 149 select DYNAMIC_SIGFRAME 150 select EDAC_ATOMIC_SCRUB 151 select EDAC_SUPPORT 152 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 153 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 154 select GENERIC_CLOCKEVENTS_MIN_ADJUST 155 select GENERIC_CMOS_UPDATE 156 select GENERIC_CPU_AUTOPROBE 157 select GENERIC_CPU_DEVICES 158 select GENERIC_CPU_VULNERABILITIES 159 select GENERIC_EARLY_IOREMAP 160 select GENERIC_ENTRY 161 select GENERIC_IOMAP 162 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 163 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 164 select GENERIC_IRQ_MIGRATION if SMP 165 select GENERIC_IRQ_PROBE 166 select GENERIC_IRQ_RESERVATION_MODE 167 select GENERIC_IRQ_SHOW 168 select GENERIC_PENDING_IRQ if SMP 169 select GENERIC_PTDUMP 170 select GENERIC_SMP_IDLE_THREAD 171 select GENERIC_TIME_VSYSCALL 172 select GENERIC_GETTIMEOFDAY 173 select GENERIC_VDSO_TIME_NS 174 select GENERIC_VDSO_OVERFLOW_PROTECT 175 select GUP_GET_PXX_LOW_HIGH if X86_PAE 176 select HARDIRQS_SW_RESEND 177 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 178 select HAS_IOPORT 179 select HAVE_ACPI_APEI if ACPI 180 select HAVE_ACPI_APEI_NMI if ACPI 181 select HAVE_ALIGNED_STRUCT_PAGE 182 select HAVE_ARCH_AUDITSYSCALL 183 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 184 select HAVE_ARCH_HUGE_VMALLOC if X86_64 185 select HAVE_ARCH_JUMP_LABEL 186 select HAVE_ARCH_JUMP_LABEL_RELATIVE 187 select HAVE_ARCH_KASAN if X86_64 188 select HAVE_ARCH_KASAN_VMALLOC if X86_64 189 select HAVE_ARCH_KFENCE 190 select HAVE_ARCH_KMSAN if X86_64 191 select HAVE_ARCH_KGDB 192 select HAVE_ARCH_MMAP_RND_BITS if MMU 193 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 194 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 195 select HAVE_ARCH_PREL32_RELOCATIONS 196 select HAVE_ARCH_SECCOMP_FILTER 197 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 198 select HAVE_ARCH_STACKLEAK 199 select HAVE_ARCH_TRACEHOOK 200 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 201 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 202 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 203 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 204 select HAVE_ARCH_VMAP_STACK if X86_64 205 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 206 select HAVE_ARCH_WITHIN_STACK_FRAMES 207 select HAVE_ASM_MODVERSIONS 208 select HAVE_CMPXCHG_DOUBLE 209 select HAVE_CMPXCHG_LOCAL 210 select HAVE_CONTEXT_TRACKING_USER if X86_64 211 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 212 select HAVE_C_RECORDMCOUNT 213 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 214 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 215 select HAVE_BUILDTIME_MCOUNT_SORT 216 select HAVE_DEBUG_KMEMLEAK 217 select HAVE_DMA_CONTIGUOUS 218 select HAVE_DYNAMIC_FTRACE 219 select HAVE_DYNAMIC_FTRACE_WITH_REGS 220 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 221 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 222 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 223 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 224 select HAVE_EBPF_JIT 225 select HAVE_EFFICIENT_UNALIGNED_ACCESS 226 select HAVE_EISA 227 select HAVE_EXIT_THREAD 228 select HAVE_GUP_FAST 229 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 230 select HAVE_FTRACE_MCOUNT_RECORD 231 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 232 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 233 select HAVE_FUNCTION_TRACER 234 select HAVE_GCC_PLUGINS 235 select HAVE_HW_BREAKPOINT 236 select HAVE_IOREMAP_PROT 237 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 238 select HAVE_IRQ_TIME_ACCOUNTING 239 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 240 select HAVE_KERNEL_BZIP2 241 select HAVE_KERNEL_GZIP 242 select HAVE_KERNEL_LZ4 243 select HAVE_KERNEL_LZMA 244 select HAVE_KERNEL_LZO 245 select HAVE_KERNEL_XZ 246 select HAVE_KERNEL_ZSTD 247 select HAVE_KPROBES 248 select HAVE_KPROBES_ON_FTRACE 249 select HAVE_FUNCTION_ERROR_INJECTION 250 select HAVE_KRETPROBES 251 select HAVE_RETHOOK 252 select HAVE_LIVEPATCH if X86_64 253 select HAVE_MIXED_BREAKPOINTS_REGS 254 select HAVE_MOD_ARCH_SPECIFIC 255 select HAVE_MOVE_PMD 256 select HAVE_MOVE_PUD 257 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 258 select HAVE_NMI 259 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 260 select HAVE_OBJTOOL if X86_64 261 select HAVE_OPTPROBES 262 select HAVE_PAGE_SIZE_4KB 263 select HAVE_PCSPKR_PLATFORM 264 select HAVE_PERF_EVENTS 265 select HAVE_PERF_EVENTS_NMI 266 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 267 select HAVE_PCI 268 select HAVE_PERF_REGS 269 select HAVE_PERF_USER_STACK_DUMP 270 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 271 select MMU_GATHER_MERGE_VMAS 272 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 273 select HAVE_REGS_AND_STACK_ACCESS_API 274 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 275 select HAVE_FUNCTION_ARG_ACCESS_API 276 select HAVE_SETUP_PER_CPU_AREA 277 select HAVE_SOFTIRQ_ON_OWN_STACK 278 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 279 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 280 select HAVE_STATIC_CALL 281 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 282 select HAVE_PREEMPT_DYNAMIC_CALL 283 select HAVE_RSEQ 284 select HAVE_RUST if X86_64 285 select HAVE_SYSCALL_TRACEPOINTS 286 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 287 select HAVE_UNSTABLE_SCHED_CLOCK 288 select HAVE_USER_RETURN_NOTIFIER 289 select HAVE_GENERIC_VDSO 290 select HOTPLUG_PARALLEL if SMP && X86_64 291 select HOTPLUG_SMT if SMP 292 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 293 select IRQ_FORCED_THREADING 294 select LOCK_MM_AND_FIND_VMA 295 select NEED_PER_CPU_EMBED_FIRST_CHUNK 296 select NEED_PER_CPU_PAGE_FIRST_CHUNK 297 select NEED_SG_DMA_LENGTH 298 select PCI_DOMAINS if PCI 299 select PCI_LOCKLESS_CONFIG if PCI 300 select PERF_EVENTS 301 select RTC_LIB 302 select RTC_MC146818_LIB 303 select SPARSE_IRQ 304 select SYSCTL_EXCEPTION_TRACE 305 select THREAD_INFO_IN_TASK 306 select TRACE_IRQFLAGS_SUPPORT 307 select TRACE_IRQFLAGS_NMI_SUPPORT 308 select USER_STACKTRACE_SUPPORT 309 select HAVE_ARCH_KCSAN if X86_64 310 select PROC_PID_ARCH_STATUS if PROC_FS 311 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 312 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 313 select FUNCTION_ALIGNMENT_4B 314 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 315 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 316 317config INSTRUCTION_DECODER 318 def_bool y 319 depends on KPROBES || PERF_EVENTS || UPROBES 320 321config OUTPUT_FORMAT 322 string 323 default "elf32-i386" if X86_32 324 default "elf64-x86-64" if X86_64 325 326config LOCKDEP_SUPPORT 327 def_bool y 328 329config STACKTRACE_SUPPORT 330 def_bool y 331 332config MMU 333 def_bool y 334 335config ARCH_MMAP_RND_BITS_MIN 336 default 28 if 64BIT 337 default 8 338 339config ARCH_MMAP_RND_BITS_MAX 340 default 32 if 64BIT 341 default 16 342 343config ARCH_MMAP_RND_COMPAT_BITS_MIN 344 default 8 345 346config ARCH_MMAP_RND_COMPAT_BITS_MAX 347 default 16 348 349config SBUS 350 bool 351 352config GENERIC_ISA_DMA 353 def_bool y 354 depends on ISA_DMA_API 355 356config GENERIC_CSUM 357 bool 358 default y if KMSAN || KASAN 359 360config GENERIC_BUG 361 def_bool y 362 depends on BUG 363 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 364 365config GENERIC_BUG_RELATIVE_POINTERS 366 bool 367 368config ARCH_MAY_HAVE_PC_FDC 369 def_bool y 370 depends on ISA_DMA_API 371 372config GENERIC_CALIBRATE_DELAY 373 def_bool y 374 375config ARCH_HAS_CPU_RELAX 376 def_bool y 377 378config ARCH_HIBERNATION_POSSIBLE 379 def_bool y 380 381config ARCH_SUSPEND_POSSIBLE 382 def_bool y 383 384config AUDIT_ARCH 385 def_bool y if X86_64 386 387config KASAN_SHADOW_OFFSET 388 hex 389 depends on KASAN 390 default 0xdffffc0000000000 391 392config HAVE_INTEL_TXT 393 def_bool y 394 depends on INTEL_IOMMU && ACPI 395 396config X86_64_SMP 397 def_bool y 398 depends on X86_64 && SMP 399 400config ARCH_SUPPORTS_UPROBES 401 def_bool y 402 403config FIX_EARLYCON_MEM 404 def_bool y 405 406config DYNAMIC_PHYSICAL_MASK 407 bool 408 409config PGTABLE_LEVELS 410 int 411 default 5 if X86_5LEVEL 412 default 4 if X86_64 413 default 3 if X86_PAE 414 default 2 415 416config CC_HAS_SANE_STACKPROTECTOR 417 bool 418 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 419 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 420 help 421 We have to make sure stack protector is unconditionally disabled if 422 the compiler produces broken code or if it does not let us control 423 the segment on 32-bit kernels. 424 425menu "Processor type and features" 426 427config SMP 428 bool "Symmetric multi-processing support" 429 help 430 This enables support for systems with more than one CPU. If you have 431 a system with only one CPU, say N. If you have a system with more 432 than one CPU, say Y. 433 434 If you say N here, the kernel will run on uni- and multiprocessor 435 machines, but will use only one CPU of a multiprocessor machine. If 436 you say Y here, the kernel will run on many, but not all, 437 uniprocessor machines. On a uniprocessor machine, the kernel 438 will run faster if you say N here. 439 440 Note that if you say Y here and choose architecture "586" or 441 "Pentium" under "Processor family", the kernel will not work on 486 442 architectures. Similarly, multiprocessor kernels for the "PPro" 443 architecture may not work on all Pentium based boards. 444 445 People using multiprocessor machines who say Y here should also say 446 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 447 Management" code will be disabled if you say Y here. 448 449 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 450 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 451 <http://www.tldp.org/docs.html#howto>. 452 453 If you don't know what to do here, say N. 454 455config X86_X2APIC 456 bool "Support x2apic" 457 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 458 help 459 This enables x2apic support on CPUs that have this feature. 460 461 This allows 32-bit apic IDs (so it can support very large systems), 462 and accesses the local apic via MSRs not via mmio. 463 464 Some Intel systems circa 2022 and later are locked into x2APIC mode 465 and can not fall back to the legacy APIC modes if SGX or TDX are 466 enabled in the BIOS. They will boot with very reduced functionality 467 without enabling this option. 468 469 If you don't know what to do here, say N. 470 471config X86_POSTED_MSI 472 bool "Enable MSI and MSI-x delivery by posted interrupts" 473 depends on X86_64 && IRQ_REMAP 474 help 475 This enables MSIs that are under interrupt remapping to be delivered as 476 posted interrupts to the host kernel. Interrupt throughput can 477 potentially be improved by coalescing CPU notifications during high 478 frequency bursts. 479 480 If you don't know what to do here, say N. 481 482config X86_MPPARSE 483 bool "Enable MPS table" if ACPI 484 default y 485 depends on X86_LOCAL_APIC 486 help 487 For old smp systems that do not have proper acpi support. Newer systems 488 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 489 490config X86_CPU_RESCTRL 491 bool "x86 CPU resource control support" 492 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 493 select KERNFS 494 select PROC_CPU_RESCTRL if PROC_FS 495 help 496 Enable x86 CPU resource control support. 497 498 Provide support for the allocation and monitoring of system resources 499 usage by the CPU. 500 501 Intel calls this Intel Resource Director Technology 502 (Intel(R) RDT). More information about RDT can be found in the 503 Intel x86 Architecture Software Developer Manual. 504 505 AMD calls this AMD Platform Quality of Service (AMD QoS). 506 More information about AMD QoS can be found in the AMD64 Technology 507 Platform Quality of Service Extensions manual. 508 509 Say N if unsure. 510 511config X86_FRED 512 bool "Flexible Return and Event Delivery" 513 depends on X86_64 514 help 515 When enabled, try to use Flexible Return and Event Delivery 516 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 517 ring transitions and exception/interrupt handling if the 518 system supports it. 519 520config X86_BIGSMP 521 bool "Support for big SMP systems with more than 8 CPUs" 522 depends on SMP && X86_32 523 help 524 This option is needed for the systems that have more than 8 CPUs. 525 526config X86_EXTENDED_PLATFORM 527 bool "Support for extended (non-PC) x86 platforms" 528 default y 529 help 530 If you disable this option then the kernel will only support 531 standard PC platforms. (which covers the vast majority of 532 systems out there.) 533 534 If you enable this option then you'll be able to select support 535 for the following non-PC x86 platforms, depending on the value of 536 CONFIG_64BIT. 537 538 32-bit platforms (CONFIG_64BIT=n): 539 Goldfish (Android emulator) 540 AMD Elan 541 RDC R-321x SoC 542 SGI 320/540 (Visual Workstation) 543 STA2X11-based (e.g. Northville) 544 Moorestown MID devices 545 546 64-bit platforms (CONFIG_64BIT=y): 547 Numascale NumaChip 548 ScaleMP vSMP 549 SGI Ultraviolet 550 551 If you have one of these systems, or if you want to build a 552 generic distribution kernel, say Y here - otherwise say N. 553 554# This is an alphabetically sorted list of 64 bit extended platforms 555# Please maintain the alphabetic order if and when there are additions 556config X86_NUMACHIP 557 bool "Numascale NumaChip" 558 depends on X86_64 559 depends on X86_EXTENDED_PLATFORM 560 depends on NUMA 561 depends on SMP 562 depends on X86_X2APIC 563 depends on PCI_MMCONFIG 564 help 565 Adds support for Numascale NumaChip large-SMP systems. Needed to 566 enable more than ~168 cores. 567 If you don't have one of these, you should say N here. 568 569config X86_VSMP 570 bool "ScaleMP vSMP" 571 select HYPERVISOR_GUEST 572 select PARAVIRT 573 depends on X86_64 && PCI 574 depends on X86_EXTENDED_PLATFORM 575 depends on SMP 576 help 577 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 578 supposed to run on these EM64T-based machines. Only choose this option 579 if you have one of these machines. 580 581config X86_UV 582 bool "SGI Ultraviolet" 583 depends on X86_64 584 depends on X86_EXTENDED_PLATFORM 585 depends on NUMA 586 depends on EFI 587 depends on KEXEC_CORE 588 depends on X86_X2APIC 589 depends on PCI 590 help 591 This option is needed in order to support SGI Ultraviolet systems. 592 If you don't have one of these, you should say N here. 593 594# Following is an alphabetically sorted list of 32 bit extended platforms 595# Please maintain the alphabetic order if and when there are additions 596 597config X86_GOLDFISH 598 bool "Goldfish (Virtual Platform)" 599 depends on X86_EXTENDED_PLATFORM 600 help 601 Enable support for the Goldfish virtual platform used primarily 602 for Android development. Unless you are building for the Android 603 Goldfish emulator say N here. 604 605config X86_INTEL_CE 606 bool "CE4100 TV platform" 607 depends on PCI 608 depends on PCI_GODIRECT 609 depends on X86_IO_APIC 610 depends on X86_32 611 depends on X86_EXTENDED_PLATFORM 612 select X86_REBOOTFIXUPS 613 select OF 614 select OF_EARLY_FLATTREE 615 help 616 Select for the Intel CE media processor (CE4100) SOC. 617 This option compiles in support for the CE4100 SOC for settop 618 boxes and media devices. 619 620config X86_INTEL_MID 621 bool "Intel MID platform support" 622 depends on X86_EXTENDED_PLATFORM 623 depends on X86_PLATFORM_DEVICES 624 depends on PCI 625 depends on X86_64 || (PCI_GOANY && X86_32) 626 depends on X86_IO_APIC 627 select I2C 628 select DW_APB_TIMER 629 select INTEL_SCU_PCI 630 help 631 Select to build a kernel capable of supporting Intel MID (Mobile 632 Internet Device) platform systems which do not have the PCI legacy 633 interfaces. If you are building for a PC class system say N here. 634 635 Intel MID platforms are based on an Intel processor and chipset which 636 consume less power than most of the x86 derivatives. 637 638config X86_INTEL_QUARK 639 bool "Intel Quark platform support" 640 depends on X86_32 641 depends on X86_EXTENDED_PLATFORM 642 depends on X86_PLATFORM_DEVICES 643 depends on X86_TSC 644 depends on PCI 645 depends on PCI_GOANY 646 depends on X86_IO_APIC 647 select IOSF_MBI 648 select INTEL_IMR 649 select COMMON_CLK 650 help 651 Select to include support for Quark X1000 SoC. 652 Say Y here if you have a Quark based system such as the Arduino 653 compatible Intel Galileo. 654 655config X86_INTEL_LPSS 656 bool "Intel Low Power Subsystem Support" 657 depends on X86 && ACPI && PCI 658 select COMMON_CLK 659 select PINCTRL 660 select IOSF_MBI 661 help 662 Select to build support for Intel Low Power Subsystem such as 663 found on Intel Lynxpoint PCH. Selecting this option enables 664 things like clock tree (common clock framework) and pincontrol 665 which are needed by the LPSS peripheral drivers. 666 667config X86_AMD_PLATFORM_DEVICE 668 bool "AMD ACPI2Platform devices support" 669 depends on ACPI 670 select COMMON_CLK 671 select PINCTRL 672 help 673 Select to interpret AMD specific ACPI device to platform device 674 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 675 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 676 implemented under PINCTRL subsystem. 677 678config IOSF_MBI 679 tristate "Intel SoC IOSF Sideband support for SoC platforms" 680 depends on PCI 681 help 682 This option enables sideband register access support for Intel SoC 683 platforms. On these platforms the IOSF sideband is used in lieu of 684 MSR's for some register accesses, mostly but not limited to thermal 685 and power. Drivers may query the availability of this device to 686 determine if they need the sideband in order to work on these 687 platforms. The sideband is available on the following SoC products. 688 This list is not meant to be exclusive. 689 - BayTrail 690 - Braswell 691 - Quark 692 693 You should say Y if you are running a kernel on one of these SoC's. 694 695config IOSF_MBI_DEBUG 696 bool "Enable IOSF sideband access through debugfs" 697 depends on IOSF_MBI && DEBUG_FS 698 help 699 Select this option to expose the IOSF sideband access registers (MCR, 700 MDR, MCRX) through debugfs to write and read register information from 701 different units on the SoC. This is most useful for obtaining device 702 state information for debug and analysis. As this is a general access 703 mechanism, users of this option would have specific knowledge of the 704 device they want to access. 705 706 If you don't require the option or are in doubt, say N. 707 708config X86_RDC321X 709 bool "RDC R-321x SoC" 710 depends on X86_32 711 depends on X86_EXTENDED_PLATFORM 712 select M486 713 select X86_REBOOTFIXUPS 714 help 715 This option is needed for RDC R-321x system-on-chip, also known 716 as R-8610-(G). 717 If you don't have one of these chips, you should say N here. 718 719config X86_32_NON_STANDARD 720 bool "Support non-standard 32-bit SMP architectures" 721 depends on X86_32 && SMP 722 depends on X86_EXTENDED_PLATFORM 723 help 724 This option compiles in the bigsmp and STA2X11 default 725 subarchitectures. It is intended for a generic binary 726 kernel. If you select them all, kernel will probe it one by 727 one and will fallback to default. 728 729# Alphabetically sorted list of Non standard 32 bit platforms 730 731config X86_SUPPORTS_MEMORY_FAILURE 732 def_bool y 733 # MCE code calls memory_failure(): 734 depends on X86_MCE 735 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 736 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 737 depends on X86_64 || !SPARSEMEM 738 select ARCH_SUPPORTS_MEMORY_FAILURE 739 740config STA2X11 741 bool "STA2X11 Companion Chip Support" 742 depends on X86_32_NON_STANDARD && PCI 743 select SWIOTLB 744 select MFD_STA2X11 745 select GPIOLIB 746 help 747 This adds support for boards based on the STA2X11 IO-Hub, 748 a.k.a. "ConneXt". The chip is used in place of the standard 749 PC chipset, so all "standard" peripherals are missing. If this 750 option is selected the kernel will still be able to boot on 751 standard PC machines. 752 753config X86_32_IRIS 754 tristate "Eurobraille/Iris poweroff module" 755 depends on X86_32 756 help 757 The Iris machines from EuroBraille do not have APM or ACPI support 758 to shut themselves down properly. A special I/O sequence is 759 needed to do so, which is what this module does at 760 kernel shutdown. 761 762 This is only for Iris machines from EuroBraille. 763 764 If unused, say N. 765 766config SCHED_OMIT_FRAME_POINTER 767 def_bool y 768 prompt "Single-depth WCHAN output" 769 depends on X86 770 help 771 Calculate simpler /proc/<PID>/wchan values. If this option 772 is disabled then wchan values will recurse back to the 773 caller function. This provides more accurate wchan values, 774 at the expense of slightly more scheduling overhead. 775 776 If in doubt, say "Y". 777 778menuconfig HYPERVISOR_GUEST 779 bool "Linux guest support" 780 help 781 Say Y here to enable options for running Linux under various hyper- 782 visors. This option enables basic hypervisor detection and platform 783 setup. 784 785 If you say N, all options in this submenu will be skipped and 786 disabled, and Linux guest support won't be built in. 787 788if HYPERVISOR_GUEST 789 790config PARAVIRT 791 bool "Enable paravirtualization code" 792 depends on HAVE_STATIC_CALL 793 help 794 This changes the kernel so it can modify itself when it is run 795 under a hypervisor, potentially improving performance significantly 796 over full virtualization. However, when run without a hypervisor 797 the kernel is theoretically slower and slightly larger. 798 799config PARAVIRT_XXL 800 bool 801 802config PARAVIRT_DEBUG 803 bool "paravirt-ops debugging" 804 depends on PARAVIRT && DEBUG_KERNEL 805 help 806 Enable to debug paravirt_ops internals. Specifically, BUG if 807 a paravirt_op is missing when it is called. 808 809config PARAVIRT_SPINLOCKS 810 bool "Paravirtualization layer for spinlocks" 811 depends on PARAVIRT && SMP 812 help 813 Paravirtualized spinlocks allow a pvops backend to replace the 814 spinlock implementation with something virtualization-friendly 815 (for example, block the virtual CPU rather than spinning). 816 817 It has a minimal impact on native kernels and gives a nice performance 818 benefit on paravirtualized KVM / Xen kernels. 819 820 If you are unsure how to answer this question, answer Y. 821 822config X86_HV_CALLBACK_VECTOR 823 def_bool n 824 825source "arch/x86/xen/Kconfig" 826 827config KVM_GUEST 828 bool "KVM Guest support (including kvmclock)" 829 depends on PARAVIRT 830 select PARAVIRT_CLOCK 831 select ARCH_CPUIDLE_HALTPOLL 832 select X86_HV_CALLBACK_VECTOR 833 default y 834 help 835 This option enables various optimizations for running under the KVM 836 hypervisor. It includes a paravirtualized clock, so that instead 837 of relying on a PIT (or probably other) emulation by the 838 underlying device model, the host provides the guest with 839 timing infrastructure such as time of day, and system time 840 841config ARCH_CPUIDLE_HALTPOLL 842 def_bool n 843 prompt "Disable host haltpoll when loading haltpoll driver" 844 help 845 If virtualized under KVM, disable host haltpoll. 846 847config PVH 848 bool "Support for running PVH guests" 849 help 850 This option enables the PVH entry point for guest virtual machines 851 as specified in the x86/HVM direct boot ABI. 852 853config PARAVIRT_TIME_ACCOUNTING 854 bool "Paravirtual steal time accounting" 855 depends on PARAVIRT 856 help 857 Select this option to enable fine granularity task steal time 858 accounting. Time spent executing other tasks in parallel with 859 the current vCPU is discounted from the vCPU power. To account for 860 that, there can be a small performance impact. 861 862 If in doubt, say N here. 863 864config PARAVIRT_CLOCK 865 bool 866 867config JAILHOUSE_GUEST 868 bool "Jailhouse non-root cell support" 869 depends on X86_64 && PCI 870 select X86_PM_TIMER 871 help 872 This option allows to run Linux as guest in a Jailhouse non-root 873 cell. You can leave this option disabled if you only want to start 874 Jailhouse and run Linux afterwards in the root cell. 875 876config ACRN_GUEST 877 bool "ACRN Guest support" 878 depends on X86_64 879 select X86_HV_CALLBACK_VECTOR 880 help 881 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 882 a flexible, lightweight reference open-source hypervisor, built with 883 real-time and safety-criticality in mind. It is built for embedded 884 IOT with small footprint and real-time features. More details can be 885 found in https://projectacrn.org/. 886 887config INTEL_TDX_GUEST 888 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 889 depends on X86_64 && CPU_SUP_INTEL 890 depends on X86_X2APIC 891 depends on EFI_STUB 892 select ARCH_HAS_CC_PLATFORM 893 select X86_MEM_ENCRYPT 894 select X86_MCE 895 select UNACCEPTED_MEMORY 896 help 897 Support running as a guest under Intel TDX. Without this support, 898 the guest kernel can not boot or run under TDX. 899 TDX includes memory encryption and integrity capabilities 900 which protect the confidentiality and integrity of guest 901 memory contents and CPU state. TDX guests are protected from 902 some attacks from the VMM. 903 904endif # HYPERVISOR_GUEST 905 906source "arch/x86/Kconfig.cpu" 907 908config HPET_TIMER 909 def_bool X86_64 910 prompt "HPET Timer Support" if X86_32 911 help 912 Use the IA-PC HPET (High Precision Event Timer) to manage 913 time in preference to the PIT and RTC, if a HPET is 914 present. 915 HPET is the next generation timer replacing legacy 8254s. 916 The HPET provides a stable time base on SMP 917 systems, unlike the TSC, but it is more expensive to access, 918 as it is off-chip. The interface used is documented 919 in the HPET spec, revision 1. 920 921 You can safely choose Y here. However, HPET will only be 922 activated if the platform and the BIOS support this feature. 923 Otherwise the 8254 will be used for timing services. 924 925 Choose N to continue using the legacy 8254 timer. 926 927config HPET_EMULATE_RTC 928 def_bool y 929 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 930 931# Mark as expert because too many people got it wrong. 932# The code disables itself when not needed. 933config DMI 934 default y 935 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 936 bool "Enable DMI scanning" if EXPERT 937 help 938 Enabled scanning of DMI to identify machine quirks. Say Y 939 here unless you have verified that your setup is not 940 affected by entries in the DMI blacklist. Required by PNP 941 BIOS code. 942 943config GART_IOMMU 944 bool "Old AMD GART IOMMU support" 945 select DMA_OPS 946 select IOMMU_HELPER 947 select SWIOTLB 948 depends on X86_64 && PCI && AMD_NB 949 help 950 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 951 GART based hardware IOMMUs. 952 953 The GART supports full DMA access for devices with 32-bit access 954 limitations, on systems with more than 3 GB. This is usually needed 955 for USB, sound, many IDE/SATA chipsets and some other devices. 956 957 Newer systems typically have a modern AMD IOMMU, supported via 958 the CONFIG_AMD_IOMMU=y config option. 959 960 In normal configurations this driver is only active when needed: 961 there's more than 3 GB of memory and the system contains a 962 32-bit limited device. 963 964 If unsure, say Y. 965 966config BOOT_VESA_SUPPORT 967 bool 968 help 969 If true, at least one selected framebuffer driver can take advantage 970 of VESA video modes set at an early boot stage via the vga= parameter. 971 972config MAXSMP 973 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 974 depends on X86_64 && SMP && DEBUG_KERNEL 975 select CPUMASK_OFFSTACK 976 help 977 Enable maximum number of CPUS and NUMA Nodes for this architecture. 978 If unsure, say N. 979 980# 981# The maximum number of CPUs supported: 982# 983# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 984# and which can be configured interactively in the 985# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 986# 987# The ranges are different on 32-bit and 64-bit kernels, depending on 988# hardware capabilities and scalability features of the kernel. 989# 990# ( If MAXSMP is enabled we just use the highest possible value and disable 991# interactive configuration. ) 992# 993 994config NR_CPUS_RANGE_BEGIN 995 int 996 default NR_CPUS_RANGE_END if MAXSMP 997 default 1 if !SMP 998 default 2 999 1000config NR_CPUS_RANGE_END 1001 int 1002 depends on X86_32 1003 default 64 if SMP && X86_BIGSMP 1004 default 8 if SMP && !X86_BIGSMP 1005 default 1 if !SMP 1006 1007config NR_CPUS_RANGE_END 1008 int 1009 depends on X86_64 1010 default 8192 if SMP && CPUMASK_OFFSTACK 1011 default 512 if SMP && !CPUMASK_OFFSTACK 1012 default 1 if !SMP 1013 1014config NR_CPUS_DEFAULT 1015 int 1016 depends on X86_32 1017 default 32 if X86_BIGSMP 1018 default 8 if SMP 1019 default 1 if !SMP 1020 1021config NR_CPUS_DEFAULT 1022 int 1023 depends on X86_64 1024 default 8192 if MAXSMP 1025 default 64 if SMP 1026 default 1 if !SMP 1027 1028config NR_CPUS 1029 int "Maximum number of CPUs" if SMP && !MAXSMP 1030 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1031 default NR_CPUS_DEFAULT 1032 help 1033 This allows you to specify the maximum number of CPUs which this 1034 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1035 supported value is 8192, otherwise the maximum value is 512. The 1036 minimum value which makes sense is 2. 1037 1038 This is purely to save memory: each supported CPU adds about 8KB 1039 to the kernel image. 1040 1041config SCHED_CLUSTER 1042 bool "Cluster scheduler support" 1043 depends on SMP 1044 default y 1045 help 1046 Cluster scheduler support improves the CPU scheduler's decision 1047 making when dealing with machines that have clusters of CPUs. 1048 Cluster usually means a couple of CPUs which are placed closely 1049 by sharing mid-level caches, last-level cache tags or internal 1050 busses. 1051 1052config SCHED_SMT 1053 def_bool y if SMP 1054 1055config SCHED_MC 1056 def_bool y 1057 prompt "Multi-core scheduler support" 1058 depends on SMP 1059 help 1060 Multi-core scheduler support improves the CPU scheduler's decision 1061 making when dealing with multi-core CPU chips at a cost of slightly 1062 increased overhead in some places. If unsure say N here. 1063 1064config SCHED_MC_PRIO 1065 bool "CPU core priorities scheduler support" 1066 depends on SCHED_MC 1067 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1068 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1069 select CPU_FREQ 1070 default y 1071 help 1072 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1073 core ordering determined at manufacturing time, which allows 1074 certain cores to reach higher turbo frequencies (when running 1075 single threaded workloads) than others. 1076 1077 Enabling this kernel feature teaches the scheduler about 1078 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1079 scheduler's CPU selection logic accordingly, so that higher 1080 overall system performance can be achieved. 1081 1082 This feature will have no effect on CPUs without this feature. 1083 1084 If unsure say Y here. 1085 1086config UP_LATE_INIT 1087 def_bool y 1088 depends on !SMP && X86_LOCAL_APIC 1089 1090config X86_UP_APIC 1091 bool "Local APIC support on uniprocessors" if !PCI_MSI 1092 default PCI_MSI 1093 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1094 help 1095 A local APIC (Advanced Programmable Interrupt Controller) is an 1096 integrated interrupt controller in the CPU. If you have a single-CPU 1097 system which has a processor with a local APIC, you can say Y here to 1098 enable and use it. If you say Y here even though your machine doesn't 1099 have a local APIC, then the kernel will still run with no slowdown at 1100 all. The local APIC supports CPU-generated self-interrupts (timer, 1101 performance counters), and the NMI watchdog which detects hard 1102 lockups. 1103 1104config X86_UP_IOAPIC 1105 bool "IO-APIC support on uniprocessors" 1106 depends on X86_UP_APIC 1107 help 1108 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1109 SMP-capable replacement for PC-style interrupt controllers. Most 1110 SMP systems and many recent uniprocessor systems have one. 1111 1112 If you have a single-CPU system with an IO-APIC, you can say Y here 1113 to use it. If you say Y here even though your machine doesn't have 1114 an IO-APIC, then the kernel will still run with no slowdown at all. 1115 1116config X86_LOCAL_APIC 1117 def_bool y 1118 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1119 select IRQ_DOMAIN_HIERARCHY 1120 1121config ACPI_MADT_WAKEUP 1122 def_bool y 1123 depends on X86_64 1124 depends on ACPI 1125 depends on SMP 1126 depends on X86_LOCAL_APIC 1127 1128config X86_IO_APIC 1129 def_bool y 1130 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1131 1132config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1133 bool "Reroute for broken boot IRQs" 1134 depends on X86_IO_APIC 1135 help 1136 This option enables a workaround that fixes a source of 1137 spurious interrupts. This is recommended when threaded 1138 interrupt handling is used on systems where the generation of 1139 superfluous "boot interrupts" cannot be disabled. 1140 1141 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1142 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1143 kernel does during interrupt handling). On chipsets where this 1144 boot IRQ generation cannot be disabled, this workaround keeps 1145 the original IRQ line masked so that only the equivalent "boot 1146 IRQ" is delivered to the CPUs. The workaround also tells the 1147 kernel to set up the IRQ handler on the boot IRQ line. In this 1148 way only one interrupt is delivered to the kernel. Otherwise 1149 the spurious second interrupt may cause the kernel to bring 1150 down (vital) interrupt lines. 1151 1152 Only affects "broken" chipsets. Interrupt sharing may be 1153 increased on these systems. 1154 1155config X86_MCE 1156 bool "Machine Check / overheating reporting" 1157 select GENERIC_ALLOCATOR 1158 default y 1159 help 1160 Machine Check support allows the processor to notify the 1161 kernel if it detects a problem (e.g. overheating, data corruption). 1162 The action the kernel takes depends on the severity of the problem, 1163 ranging from warning messages to halting the machine. 1164 1165config X86_MCELOG_LEGACY 1166 bool "Support for deprecated /dev/mcelog character device" 1167 depends on X86_MCE 1168 help 1169 Enable support for /dev/mcelog which is needed by the old mcelog 1170 userspace logging daemon. Consider switching to the new generation 1171 rasdaemon solution. 1172 1173config X86_MCE_INTEL 1174 def_bool y 1175 prompt "Intel MCE features" 1176 depends on X86_MCE && X86_LOCAL_APIC 1177 help 1178 Additional support for intel specific MCE features such as 1179 the thermal monitor. 1180 1181config X86_MCE_AMD 1182 def_bool y 1183 prompt "AMD MCE features" 1184 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1185 help 1186 Additional support for AMD specific MCE features such as 1187 the DRAM Error Threshold. 1188 1189config X86_ANCIENT_MCE 1190 bool "Support for old Pentium 5 / WinChip machine checks" 1191 depends on X86_32 && X86_MCE 1192 help 1193 Include support for machine check handling on old Pentium 5 or WinChip 1194 systems. These typically need to be enabled explicitly on the command 1195 line. 1196 1197config X86_MCE_THRESHOLD 1198 depends on X86_MCE_AMD || X86_MCE_INTEL 1199 def_bool y 1200 1201config X86_MCE_INJECT 1202 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1203 tristate "Machine check injector support" 1204 help 1205 Provide support for injecting machine checks for testing purposes. 1206 If you don't know what a machine check is and you don't do kernel 1207 QA it is safe to say n. 1208 1209source "arch/x86/events/Kconfig" 1210 1211config X86_LEGACY_VM86 1212 bool "Legacy VM86 support" 1213 depends on X86_32 1214 help 1215 This option allows user programs to put the CPU into V8086 1216 mode, which is an 80286-era approximation of 16-bit real mode. 1217 1218 Some very old versions of X and/or vbetool require this option 1219 for user mode setting. Similarly, DOSEMU will use it if 1220 available to accelerate real mode DOS programs. However, any 1221 recent version of DOSEMU, X, or vbetool should be fully 1222 functional even without kernel VM86 support, as they will all 1223 fall back to software emulation. Nevertheless, if you are using 1224 a 16-bit DOS program where 16-bit performance matters, vm86 1225 mode might be faster than emulation and you might want to 1226 enable this option. 1227 1228 Note that any app that works on a 64-bit kernel is unlikely to 1229 need this option, as 64-bit kernels don't, and can't, support 1230 V8086 mode. This option is also unrelated to 16-bit protected 1231 mode and is not needed to run most 16-bit programs under Wine. 1232 1233 Enabling this option increases the complexity of the kernel 1234 and slows down exception handling a tiny bit. 1235 1236 If unsure, say N here. 1237 1238config VM86 1239 bool 1240 default X86_LEGACY_VM86 1241 1242config X86_16BIT 1243 bool "Enable support for 16-bit segments" if EXPERT 1244 default y 1245 depends on MODIFY_LDT_SYSCALL 1246 help 1247 This option is required by programs like Wine to run 16-bit 1248 protected mode legacy code on x86 processors. Disabling 1249 this option saves about 300 bytes on i386, or around 6K text 1250 plus 16K runtime memory on x86-64, 1251 1252config X86_ESPFIX32 1253 def_bool y 1254 depends on X86_16BIT && X86_32 1255 1256config X86_ESPFIX64 1257 def_bool y 1258 depends on X86_16BIT && X86_64 1259 1260config X86_VSYSCALL_EMULATION 1261 bool "Enable vsyscall emulation" if EXPERT 1262 default y 1263 depends on X86_64 1264 help 1265 This enables emulation of the legacy vsyscall page. Disabling 1266 it is roughly equivalent to booting with vsyscall=none, except 1267 that it will also disable the helpful warning if a program 1268 tries to use a vsyscall. With this option set to N, offending 1269 programs will just segfault, citing addresses of the form 1270 0xffffffffff600?00. 1271 1272 This option is required by many programs built before 2013, and 1273 care should be used even with newer programs if set to N. 1274 1275 Disabling this option saves about 7K of kernel size and 1276 possibly 4K of additional runtime pagetable memory. 1277 1278config X86_IOPL_IOPERM 1279 bool "IOPERM and IOPL Emulation" 1280 default y 1281 help 1282 This enables the ioperm() and iopl() syscalls which are necessary 1283 for legacy applications. 1284 1285 Legacy IOPL support is an overbroad mechanism which allows user 1286 space aside of accessing all 65536 I/O ports also to disable 1287 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1288 capabilities and permission from potentially active security 1289 modules. 1290 1291 The emulation restricts the functionality of the syscall to 1292 only allowing the full range I/O port access, but prevents the 1293 ability to disable interrupts from user space which would be 1294 granted if the hardware IOPL mechanism would be used. 1295 1296config TOSHIBA 1297 tristate "Toshiba Laptop support" 1298 depends on X86_32 1299 help 1300 This adds a driver to safely access the System Management Mode of 1301 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1302 not work on models with a Phoenix BIOS. The System Management Mode 1303 is used to set the BIOS and power saving options on Toshiba portables. 1304 1305 For information on utilities to make use of this driver see the 1306 Toshiba Linux utilities web site at: 1307 <http://www.buzzard.org.uk/toshiba/>. 1308 1309 Say Y if you intend to run this kernel on a Toshiba portable. 1310 Say N otherwise. 1311 1312config X86_REBOOTFIXUPS 1313 bool "Enable X86 board specific fixups for reboot" 1314 depends on X86_32 1315 help 1316 This enables chipset and/or board specific fixups to be done 1317 in order to get reboot to work correctly. This is only needed on 1318 some combinations of hardware and BIOS. The symptom, for which 1319 this config is intended, is when reboot ends with a stalled/hung 1320 system. 1321 1322 Currently, the only fixup is for the Geode machines using 1323 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1324 1325 Say Y if you want to enable the fixup. Currently, it's safe to 1326 enable this option even if you don't need it. 1327 Say N otherwise. 1328 1329config MICROCODE 1330 def_bool y 1331 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1332 1333config MICROCODE_INITRD32 1334 def_bool y 1335 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1336 1337config MICROCODE_LATE_LOADING 1338 bool "Late microcode loading (DANGEROUS)" 1339 default n 1340 depends on MICROCODE && SMP 1341 help 1342 Loading microcode late, when the system is up and executing instructions 1343 is a tricky business and should be avoided if possible. Just the sequence 1344 of synchronizing all cores and SMT threads is one fragile dance which does 1345 not guarantee that cores might not softlock after the loading. Therefore, 1346 use this at your own risk. Late loading taints the kernel unless the 1347 microcode header indicates that it is safe for late loading via the 1348 minimal revision check. This minimal revision check can be enforced on 1349 the kernel command line with "microcode.minrev=Y". 1350 1351config MICROCODE_LATE_FORCE_MINREV 1352 bool "Enforce late microcode loading minimal revision check" 1353 default n 1354 depends on MICROCODE_LATE_LOADING 1355 help 1356 To prevent that users load microcode late which modifies already 1357 in use features, newer microcode patches have a minimum revision field 1358 in the microcode header, which tells the kernel which minimum 1359 revision must be active in the CPU to safely load that new microcode 1360 late into the running system. If disabled the check will not 1361 be enforced but the kernel will be tainted when the minimal 1362 revision check fails. 1363 1364 This minimal revision check can also be controlled via the 1365 "microcode.minrev" parameter on the kernel command line. 1366 1367 If unsure say Y. 1368 1369config X86_MSR 1370 tristate "/dev/cpu/*/msr - Model-specific register support" 1371 help 1372 This device gives privileged processes access to the x86 1373 Model-Specific Registers (MSRs). It is a character device with 1374 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1375 MSR accesses are directed to a specific CPU on multi-processor 1376 systems. 1377 1378config X86_CPUID 1379 tristate "/dev/cpu/*/cpuid - CPU information support" 1380 help 1381 This device gives processes access to the x86 CPUID instruction to 1382 be executed on a specific processor. It is a character device 1383 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1384 /dev/cpu/31/cpuid. 1385 1386choice 1387 prompt "High Memory Support" 1388 default HIGHMEM4G 1389 depends on X86_32 1390 1391config NOHIGHMEM 1392 bool "off" 1393 help 1394 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1395 However, the address space of 32-bit x86 processors is only 4 1396 Gigabytes large. That means that, if you have a large amount of 1397 physical memory, not all of it can be "permanently mapped" by the 1398 kernel. The physical memory that's not permanently mapped is called 1399 "high memory". 1400 1401 If you are compiling a kernel which will never run on a machine with 1402 more than 1 Gigabyte total physical RAM, answer "off" here (default 1403 choice and suitable for most users). This will result in a "3GB/1GB" 1404 split: 3GB are mapped so that each process sees a 3GB virtual memory 1405 space and the remaining part of the 4GB virtual memory space is used 1406 by the kernel to permanently map as much physical memory as 1407 possible. 1408 1409 If the machine has between 1 and 4 Gigabytes physical RAM, then 1410 answer "4GB" here. 1411 1412 If more than 4 Gigabytes is used then answer "64GB" here. This 1413 selection turns Intel PAE (Physical Address Extension) mode on. 1414 PAE implements 3-level paging on IA32 processors. PAE is fully 1415 supported by Linux, PAE mode is implemented on all recent Intel 1416 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1417 then the kernel will not boot on CPUs that don't support PAE! 1418 1419 The actual amount of total physical memory will either be 1420 auto detected or can be forced by using a kernel command line option 1421 such as "mem=256M". (Try "man bootparam" or see the documentation of 1422 your boot loader (lilo or loadlin) about how to pass options to the 1423 kernel at boot time.) 1424 1425 If unsure, say "off". 1426 1427config HIGHMEM4G 1428 bool "4GB" 1429 help 1430 Select this if you have a 32-bit processor and between 1 and 4 1431 gigabytes of physical RAM. 1432 1433config HIGHMEM64G 1434 bool "64GB" 1435 depends on X86_HAVE_PAE 1436 select X86_PAE 1437 help 1438 Select this if you have a 32-bit processor and more than 4 1439 gigabytes of physical RAM. 1440 1441endchoice 1442 1443choice 1444 prompt "Memory split" if EXPERT 1445 default VMSPLIT_3G 1446 depends on X86_32 1447 help 1448 Select the desired split between kernel and user memory. 1449 1450 If the address range available to the kernel is less than the 1451 physical memory installed, the remaining memory will be available 1452 as "high memory". Accessing high memory is a little more costly 1453 than low memory, as it needs to be mapped into the kernel first. 1454 Note that increasing the kernel address space limits the range 1455 available to user programs, making the address space there 1456 tighter. Selecting anything other than the default 3G/1G split 1457 will also likely make your kernel incompatible with binary-only 1458 kernel modules. 1459 1460 If you are not absolutely sure what you are doing, leave this 1461 option alone! 1462 1463 config VMSPLIT_3G 1464 bool "3G/1G user/kernel split" 1465 config VMSPLIT_3G_OPT 1466 depends on !X86_PAE 1467 bool "3G/1G user/kernel split (for full 1G low memory)" 1468 config VMSPLIT_2G 1469 bool "2G/2G user/kernel split" 1470 config VMSPLIT_2G_OPT 1471 depends on !X86_PAE 1472 bool "2G/2G user/kernel split (for full 2G low memory)" 1473 config VMSPLIT_1G 1474 bool "1G/3G user/kernel split" 1475endchoice 1476 1477config PAGE_OFFSET 1478 hex 1479 default 0xB0000000 if VMSPLIT_3G_OPT 1480 default 0x80000000 if VMSPLIT_2G 1481 default 0x78000000 if VMSPLIT_2G_OPT 1482 default 0x40000000 if VMSPLIT_1G 1483 default 0xC0000000 1484 depends on X86_32 1485 1486config HIGHMEM 1487 def_bool y 1488 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1489 1490config X86_PAE 1491 bool "PAE (Physical Address Extension) Support" 1492 depends on X86_32 && X86_HAVE_PAE 1493 select PHYS_ADDR_T_64BIT 1494 select SWIOTLB 1495 help 1496 PAE is required for NX support, and furthermore enables 1497 larger swapspace support for non-overcommit purposes. It 1498 has the cost of more pagetable lookup overhead, and also 1499 consumes more pagetable space per process. 1500 1501config X86_5LEVEL 1502 bool "Enable 5-level page tables support" 1503 default y 1504 select DYNAMIC_MEMORY_LAYOUT 1505 select SPARSEMEM_VMEMMAP 1506 depends on X86_64 1507 help 1508 5-level paging enables access to larger address space: 1509 up to 128 PiB of virtual address space and 4 PiB of 1510 physical address space. 1511 1512 It will be supported by future Intel CPUs. 1513 1514 A kernel with the option enabled can be booted on machines that 1515 support 4- or 5-level paging. 1516 1517 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1518 information. 1519 1520 Say N if unsure. 1521 1522config X86_DIRECT_GBPAGES 1523 def_bool y 1524 depends on X86_64 1525 help 1526 Certain kernel features effectively disable kernel 1527 linear 1 GB mappings (even if the CPU otherwise 1528 supports them), so don't confuse the user by printing 1529 that we have them enabled. 1530 1531config X86_CPA_STATISTICS 1532 bool "Enable statistic for Change Page Attribute" 1533 depends on DEBUG_FS 1534 help 1535 Expose statistics about the Change Page Attribute mechanism, which 1536 helps to determine the effectiveness of preserving large and huge 1537 page mappings when mapping protections are changed. 1538 1539config X86_MEM_ENCRYPT 1540 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1541 select DYNAMIC_PHYSICAL_MASK 1542 def_bool n 1543 1544config AMD_MEM_ENCRYPT 1545 bool "AMD Secure Memory Encryption (SME) support" 1546 depends on X86_64 && CPU_SUP_AMD 1547 depends on EFI_STUB 1548 select DMA_COHERENT_POOL 1549 select ARCH_USE_MEMREMAP_PROT 1550 select INSTRUCTION_DECODER 1551 select ARCH_HAS_CC_PLATFORM 1552 select X86_MEM_ENCRYPT 1553 select UNACCEPTED_MEMORY 1554 help 1555 Say yes to enable support for the encryption of system memory. 1556 This requires an AMD processor that supports Secure Memory 1557 Encryption (SME). 1558 1559# Common NUMA Features 1560config NUMA 1561 bool "NUMA Memory Allocation and Scheduler Support" 1562 depends on SMP 1563 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1564 default y if X86_BIGSMP 1565 select USE_PERCPU_NUMA_NODE_ID 1566 select OF_NUMA if OF 1567 help 1568 Enable NUMA (Non-Uniform Memory Access) support. 1569 1570 The kernel will try to allocate memory used by a CPU on the 1571 local memory controller of the CPU and add some more 1572 NUMA awareness to the kernel. 1573 1574 For 64-bit this is recommended if the system is Intel Core i7 1575 (or later), AMD Opteron, or EM64T NUMA. 1576 1577 For 32-bit this is only needed if you boot a 32-bit 1578 kernel on a 64-bit NUMA platform. 1579 1580 Otherwise, you should say N. 1581 1582config AMD_NUMA 1583 def_bool y 1584 prompt "Old style AMD Opteron NUMA detection" 1585 depends on X86_64 && NUMA && PCI 1586 help 1587 Enable AMD NUMA node topology detection. You should say Y here if 1588 you have a multi processor AMD system. This uses an old method to 1589 read the NUMA configuration directly from the builtin Northbridge 1590 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1591 which also takes priority if both are compiled in. 1592 1593config X86_64_ACPI_NUMA 1594 def_bool y 1595 prompt "ACPI NUMA detection" 1596 depends on X86_64 && NUMA && ACPI && PCI 1597 select ACPI_NUMA 1598 help 1599 Enable ACPI SRAT based node topology detection. 1600 1601config NUMA_EMU 1602 bool "NUMA emulation" 1603 depends on NUMA 1604 help 1605 Enable NUMA emulation. A flat machine will be split 1606 into virtual nodes when booted with "numa=fake=N", where N is the 1607 number of nodes. This is only useful for debugging. 1608 1609config NODES_SHIFT 1610 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1611 range 1 10 1612 default "10" if MAXSMP 1613 default "6" if X86_64 1614 default "3" 1615 depends on NUMA 1616 help 1617 Specify the maximum number of NUMA Nodes available on the target 1618 system. Increases memory reserved to accommodate various tables. 1619 1620config ARCH_FLATMEM_ENABLE 1621 def_bool y 1622 depends on X86_32 && !NUMA 1623 1624config ARCH_SPARSEMEM_ENABLE 1625 def_bool y 1626 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1627 select SPARSEMEM_STATIC if X86_32 1628 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1629 1630config ARCH_SPARSEMEM_DEFAULT 1631 def_bool X86_64 || (NUMA && X86_32) 1632 1633config ARCH_SELECT_MEMORY_MODEL 1634 def_bool y 1635 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1636 1637config ARCH_MEMORY_PROBE 1638 bool "Enable sysfs memory/probe interface" 1639 depends on MEMORY_HOTPLUG 1640 help 1641 This option enables a sysfs memory/probe interface for testing. 1642 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1643 If you are unsure how to answer this question, answer N. 1644 1645config ARCH_PROC_KCORE_TEXT 1646 def_bool y 1647 depends on X86_64 && PROC_KCORE 1648 1649config ILLEGAL_POINTER_VALUE 1650 hex 1651 default 0 if X86_32 1652 default 0xdead000000000000 if X86_64 1653 1654config X86_PMEM_LEGACY_DEVICE 1655 bool 1656 1657config X86_PMEM_LEGACY 1658 tristate "Support non-standard NVDIMMs and ADR protected memory" 1659 depends on PHYS_ADDR_T_64BIT 1660 depends on BLK_DEV 1661 select X86_PMEM_LEGACY_DEVICE 1662 select NUMA_KEEP_MEMINFO if NUMA 1663 select LIBNVDIMM 1664 help 1665 Treat memory marked using the non-standard e820 type of 12 as used 1666 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1667 The kernel will offer these regions to the 'pmem' driver so 1668 they can be used for persistent storage. 1669 1670 Say Y if unsure. 1671 1672config HIGHPTE 1673 bool "Allocate 3rd-level pagetables from highmem" 1674 depends on HIGHMEM 1675 help 1676 The VM uses one page table entry for each page of physical memory. 1677 For systems with a lot of RAM, this can be wasteful of precious 1678 low memory. Setting this option will put user-space page table 1679 entries in high memory. 1680 1681config X86_CHECK_BIOS_CORRUPTION 1682 bool "Check for low memory corruption" 1683 help 1684 Periodically check for memory corruption in low memory, which 1685 is suspected to be caused by BIOS. Even when enabled in the 1686 configuration, it is disabled at runtime. Enable it by 1687 setting "memory_corruption_check=1" on the kernel command 1688 line. By default it scans the low 64k of memory every 60 1689 seconds; see the memory_corruption_check_size and 1690 memory_corruption_check_period parameters in 1691 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1692 1693 When enabled with the default parameters, this option has 1694 almost no overhead, as it reserves a relatively small amount 1695 of memory and scans it infrequently. It both detects corruption 1696 and prevents it from affecting the running system. 1697 1698 It is, however, intended as a diagnostic tool; if repeatable 1699 BIOS-originated corruption always affects the same memory, 1700 you can use memmap= to prevent the kernel from using that 1701 memory. 1702 1703config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1704 bool "Set the default setting of memory_corruption_check" 1705 depends on X86_CHECK_BIOS_CORRUPTION 1706 default y 1707 help 1708 Set whether the default state of memory_corruption_check is 1709 on or off. 1710 1711config MATH_EMULATION 1712 bool 1713 depends on MODIFY_LDT_SYSCALL 1714 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1715 help 1716 Linux can emulate a math coprocessor (used for floating point 1717 operations) if you don't have one. 486DX and Pentium processors have 1718 a math coprocessor built in, 486SX and 386 do not, unless you added 1719 a 487DX or 387, respectively. (The messages during boot time can 1720 give you some hints here ["man dmesg"].) Everyone needs either a 1721 coprocessor or this emulation. 1722 1723 If you don't have a math coprocessor, you need to say Y here; if you 1724 say Y here even though you have a coprocessor, the coprocessor will 1725 be used nevertheless. (This behavior can be changed with the kernel 1726 command line option "no387", which comes handy if your coprocessor 1727 is broken. Try "man bootparam" or see the documentation of your boot 1728 loader (lilo or loadlin) about how to pass options to the kernel at 1729 boot time.) This means that it is a good idea to say Y here if you 1730 intend to use this kernel on different machines. 1731 1732 More information about the internals of the Linux math coprocessor 1733 emulation can be found in <file:arch/x86/math-emu/README>. 1734 1735 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1736 kernel, it won't hurt. 1737 1738config MTRR 1739 def_bool y 1740 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1741 help 1742 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1743 the Memory Type Range Registers (MTRRs) may be used to control 1744 processor access to memory ranges. This is most useful if you have 1745 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1746 allows bus write transfers to be combined into a larger transfer 1747 before bursting over the PCI/AGP bus. This can increase performance 1748 of image write operations 2.5 times or more. Saying Y here creates a 1749 /proc/mtrr file which may be used to manipulate your processor's 1750 MTRRs. Typically the X server should use this. 1751 1752 This code has a reasonably generic interface so that similar 1753 control registers on other processors can be easily supported 1754 as well: 1755 1756 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1757 Registers (ARRs) which provide a similar functionality to MTRRs. For 1758 these, the ARRs are used to emulate the MTRRs. 1759 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1760 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1761 write-combining. All of these processors are supported by this code 1762 and it makes sense to say Y here if you have one of them. 1763 1764 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1765 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1766 can lead to all sorts of problems, so it's good to say Y here. 1767 1768 You can safely say Y even if your machine doesn't have MTRRs, you'll 1769 just add about 9 KB to your kernel. 1770 1771 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1772 1773config MTRR_SANITIZER 1774 def_bool y 1775 prompt "MTRR cleanup support" 1776 depends on MTRR 1777 help 1778 Convert MTRR layout from continuous to discrete, so X drivers can 1779 add writeback entries. 1780 1781 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1782 The largest mtrr entry size for a continuous block can be set with 1783 mtrr_chunk_size. 1784 1785 If unsure, say Y. 1786 1787config MTRR_SANITIZER_ENABLE_DEFAULT 1788 int "MTRR cleanup enable value (0-1)" 1789 range 0 1 1790 default "0" 1791 depends on MTRR_SANITIZER 1792 help 1793 Enable mtrr cleanup default value 1794 1795config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1796 int "MTRR cleanup spare reg num (0-7)" 1797 range 0 7 1798 default "1" 1799 depends on MTRR_SANITIZER 1800 help 1801 mtrr cleanup spare entries default, it can be changed via 1802 mtrr_spare_reg_nr=N on the kernel command line. 1803 1804config X86_PAT 1805 def_bool y 1806 prompt "x86 PAT support" if EXPERT 1807 depends on MTRR 1808 help 1809 Use PAT attributes to setup page level cache control. 1810 1811 PATs are the modern equivalents of MTRRs and are much more 1812 flexible than MTRRs. 1813 1814 Say N here if you see bootup problems (boot crash, boot hang, 1815 spontaneous reboots) or a non-working video driver. 1816 1817 If unsure, say Y. 1818 1819config ARCH_USES_PG_UNCACHED 1820 def_bool y 1821 depends on X86_PAT 1822 1823config X86_UMIP 1824 def_bool y 1825 prompt "User Mode Instruction Prevention" if EXPERT 1826 help 1827 User Mode Instruction Prevention (UMIP) is a security feature in 1828 some x86 processors. If enabled, a general protection fault is 1829 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1830 executed in user mode. These instructions unnecessarily expose 1831 information about the hardware state. 1832 1833 The vast majority of applications do not use these instructions. 1834 For the very few that do, software emulation is provided in 1835 specific cases in protected and virtual-8086 modes. Emulated 1836 results are dummy. 1837 1838config CC_HAS_IBT 1839 # GCC >= 9 and binutils >= 2.29 1840 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1841 # Clang/LLVM >= 14 1842 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1843 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1844 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1845 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1846 $(as-instr,endbr64) 1847 1848config X86_CET 1849 def_bool n 1850 help 1851 CET features configured (Shadow stack or IBT) 1852 1853config X86_KERNEL_IBT 1854 prompt "Indirect Branch Tracking" 1855 def_bool y 1856 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1857 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1858 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1859 select OBJTOOL 1860 select X86_CET 1861 help 1862 Build the kernel with support for Indirect Branch Tracking, a 1863 hardware support course-grain forward-edge Control Flow Integrity 1864 protection. It enforces that all indirect calls must land on 1865 an ENDBR instruction, as such, the compiler will instrument the 1866 code with them to make this happen. 1867 1868 In addition to building the kernel with IBT, seal all functions that 1869 are not indirect call targets, avoiding them ever becoming one. 1870 1871 This requires LTO like objtool runs and will slow down the build. It 1872 does significantly reduce the number of ENDBR instructions in the 1873 kernel image. 1874 1875config X86_INTEL_MEMORY_PROTECTION_KEYS 1876 prompt "Memory Protection Keys" 1877 def_bool y 1878 # Note: only available in 64-bit mode 1879 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1880 select ARCH_USES_HIGH_VMA_FLAGS 1881 select ARCH_HAS_PKEYS 1882 help 1883 Memory Protection Keys provides a mechanism for enforcing 1884 page-based protections, but without requiring modification of the 1885 page tables when an application changes protection domains. 1886 1887 For details, see Documentation/core-api/protection-keys.rst 1888 1889 If unsure, say y. 1890 1891choice 1892 prompt "TSX enable mode" 1893 depends on CPU_SUP_INTEL 1894 default X86_INTEL_TSX_MODE_OFF 1895 help 1896 Intel's TSX (Transactional Synchronization Extensions) feature 1897 allows to optimize locking protocols through lock elision which 1898 can lead to a noticeable performance boost. 1899 1900 On the other hand it has been shown that TSX can be exploited 1901 to form side channel attacks (e.g. TAA) and chances are there 1902 will be more of those attacks discovered in the future. 1903 1904 Therefore TSX is not enabled by default (aka tsx=off). An admin 1905 might override this decision by tsx=on the command line parameter. 1906 Even with TSX enabled, the kernel will attempt to enable the best 1907 possible TAA mitigation setting depending on the microcode available 1908 for the particular machine. 1909 1910 This option allows to set the default tsx mode between tsx=on, =off 1911 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1912 details. 1913 1914 Say off if not sure, auto if TSX is in use but it should be used on safe 1915 platforms or on if TSX is in use and the security aspect of tsx is not 1916 relevant. 1917 1918config X86_INTEL_TSX_MODE_OFF 1919 bool "off" 1920 help 1921 TSX is disabled if possible - equals to tsx=off command line parameter. 1922 1923config X86_INTEL_TSX_MODE_ON 1924 bool "on" 1925 help 1926 TSX is always enabled on TSX capable HW - equals the tsx=on command 1927 line parameter. 1928 1929config X86_INTEL_TSX_MODE_AUTO 1930 bool "auto" 1931 help 1932 TSX is enabled on TSX capable HW that is believed to be safe against 1933 side channel attacks- equals the tsx=auto command line parameter. 1934endchoice 1935 1936config X86_SGX 1937 bool "Software Guard eXtensions (SGX)" 1938 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1939 depends on CRYPTO=y 1940 depends on CRYPTO_SHA256=y 1941 select MMU_NOTIFIER 1942 select NUMA_KEEP_MEMINFO if NUMA 1943 select XARRAY_MULTI 1944 help 1945 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1946 that can be used by applications to set aside private regions of code 1947 and data, referred to as enclaves. An enclave's private memory can 1948 only be accessed by code running within the enclave. Accesses from 1949 outside the enclave, including other enclaves, are disallowed by 1950 hardware. 1951 1952 If unsure, say N. 1953 1954config X86_USER_SHADOW_STACK 1955 bool "X86 userspace shadow stack" 1956 depends on AS_WRUSS 1957 depends on X86_64 1958 select ARCH_USES_HIGH_VMA_FLAGS 1959 select X86_CET 1960 help 1961 Shadow stack protection is a hardware feature that detects function 1962 return address corruption. This helps mitigate ROP attacks. 1963 Applications must be enabled to use it, and old userspace does not 1964 get protection "for free". 1965 1966 CPUs supporting shadow stacks were first released in 2020. 1967 1968 See Documentation/arch/x86/shstk.rst for more information. 1969 1970 If unsure, say N. 1971 1972config INTEL_TDX_HOST 1973 bool "Intel Trust Domain Extensions (TDX) host support" 1974 depends on CPU_SUP_INTEL 1975 depends on X86_64 1976 depends on KVM_INTEL 1977 depends on X86_X2APIC 1978 select ARCH_KEEP_MEMBLOCK 1979 depends on CONTIG_ALLOC 1980 depends on !KEXEC_CORE 1981 depends on X86_MCE 1982 help 1983 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1984 host and certain physical attacks. This option enables necessary TDX 1985 support in the host kernel to run confidential VMs. 1986 1987 If unsure, say N. 1988 1989config EFI 1990 bool "EFI runtime service support" 1991 depends on ACPI 1992 select UCS2_STRING 1993 select EFI_RUNTIME_WRAPPERS 1994 select ARCH_USE_MEMREMAP_PROT 1995 select EFI_RUNTIME_MAP if KEXEC_CORE 1996 help 1997 This enables the kernel to use EFI runtime services that are 1998 available (such as the EFI variable services). 1999 2000 This option is only useful on systems that have EFI firmware. 2001 In addition, you should use the latest ELILO loader available 2002 at <http://elilo.sourceforge.net> in order to take advantage 2003 of EFI runtime services. However, even with this option, the 2004 resultant kernel should continue to boot on existing non-EFI 2005 platforms. 2006 2007config EFI_STUB 2008 bool "EFI stub support" 2009 depends on EFI 2010 select RELOCATABLE 2011 help 2012 This kernel feature allows a bzImage to be loaded directly 2013 by EFI firmware without the use of a bootloader. 2014 2015 See Documentation/admin-guide/efi-stub.rst for more information. 2016 2017config EFI_HANDOVER_PROTOCOL 2018 bool "EFI handover protocol (DEPRECATED)" 2019 depends on EFI_STUB 2020 default y 2021 help 2022 Select this in order to include support for the deprecated EFI 2023 handover protocol, which defines alternative entry points into the 2024 EFI stub. This is a practice that has no basis in the UEFI 2025 specification, and requires a priori knowledge on the part of the 2026 bootloader about Linux/x86 specific ways of passing the command line 2027 and initrd, and where in memory those assets may be loaded. 2028 2029 If in doubt, say Y. Even though the corresponding support is not 2030 present in upstream GRUB or other bootloaders, most distros build 2031 GRUB with numerous downstream patches applied, and may rely on the 2032 handover protocol as as result. 2033 2034config EFI_MIXED 2035 bool "EFI mixed-mode support" 2036 depends on EFI_STUB && X86_64 2037 help 2038 Enabling this feature allows a 64-bit kernel to be booted 2039 on a 32-bit firmware, provided that your CPU supports 64-bit 2040 mode. 2041 2042 Note that it is not possible to boot a mixed-mode enabled 2043 kernel via the EFI boot stub - a bootloader that supports 2044 the EFI handover protocol must be used. 2045 2046 If unsure, say N. 2047 2048config EFI_RUNTIME_MAP 2049 bool "Export EFI runtime maps to sysfs" if EXPERT 2050 depends on EFI 2051 help 2052 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2053 That memory map is required by the 2nd kernel to set up EFI virtual 2054 mappings after kexec, but can also be used for debugging purposes. 2055 2056 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2057 2058source "kernel/Kconfig.hz" 2059 2060config ARCH_SUPPORTS_KEXEC 2061 def_bool y 2062 2063config ARCH_SUPPORTS_KEXEC_FILE 2064 def_bool X86_64 2065 2066config ARCH_SELECTS_KEXEC_FILE 2067 def_bool y 2068 depends on KEXEC_FILE 2069 select HAVE_IMA_KEXEC if IMA 2070 2071config ARCH_SUPPORTS_KEXEC_PURGATORY 2072 def_bool y 2073 2074config ARCH_SUPPORTS_KEXEC_SIG 2075 def_bool y 2076 2077config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2078 def_bool y 2079 2080config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2081 def_bool y 2082 2083config ARCH_SUPPORTS_KEXEC_JUMP 2084 def_bool y 2085 2086config ARCH_SUPPORTS_CRASH_DUMP 2087 def_bool X86_64 || (X86_32 && HIGHMEM) 2088 2089config ARCH_SUPPORTS_CRASH_HOTPLUG 2090 def_bool y 2091 2092config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2093 def_bool CRASH_RESERVE 2094 2095config PHYSICAL_START 2096 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2097 default "0x1000000" 2098 help 2099 This gives the physical address where the kernel is loaded. 2100 2101 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2102 will decompress itself to above physical address and run from there. 2103 Otherwise, bzImage will run from the address where it has been loaded 2104 by the boot loader. The only exception is if it is loaded below the 2105 above physical address, in which case it will relocate itself there. 2106 2107 In normal kdump cases one does not have to set/change this option 2108 as now bzImage can be compiled as a completely relocatable image 2109 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2110 address. This option is mainly useful for the folks who don't want 2111 to use a bzImage for capturing the crash dump and want to use a 2112 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2113 to be specifically compiled to run from a specific memory area 2114 (normally a reserved region) and this option comes handy. 2115 2116 So if you are using bzImage for capturing the crash dump, 2117 leave the value here unchanged to 0x1000000 and set 2118 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2119 for capturing the crash dump change this value to start of 2120 the reserved region. In other words, it can be set based on 2121 the "X" value as specified in the "crashkernel=YM@XM" 2122 command line boot parameter passed to the panic-ed 2123 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2124 for more details about crash dumps. 2125 2126 Usage of bzImage for capturing the crash dump is recommended as 2127 one does not have to build two kernels. Same kernel can be used 2128 as production kernel and capture kernel. Above option should have 2129 gone away after relocatable bzImage support is introduced. But it 2130 is present because there are users out there who continue to use 2131 vmlinux for dump capture. This option should go away down the 2132 line. 2133 2134 Don't change this unless you know what you are doing. 2135 2136config RELOCATABLE 2137 bool "Build a relocatable kernel" 2138 default y 2139 help 2140 This builds a kernel image that retains relocation information 2141 so it can be loaded someplace besides the default 1MB. 2142 The relocations tend to make the kernel binary about 10% larger, 2143 but are discarded at runtime. 2144 2145 One use is for the kexec on panic case where the recovery kernel 2146 must live at a different physical address than the primary 2147 kernel. 2148 2149 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2150 it has been loaded at and the compile time physical address 2151 (CONFIG_PHYSICAL_START) is used as the minimum location. 2152 2153config RANDOMIZE_BASE 2154 bool "Randomize the address of the kernel image (KASLR)" 2155 depends on RELOCATABLE 2156 default y 2157 help 2158 In support of Kernel Address Space Layout Randomization (KASLR), 2159 this randomizes the physical address at which the kernel image 2160 is decompressed and the virtual address where the kernel 2161 image is mapped, as a security feature that deters exploit 2162 attempts relying on knowledge of the location of kernel 2163 code internals. 2164 2165 On 64-bit, the kernel physical and virtual addresses are 2166 randomized separately. The physical address will be anywhere 2167 between 16MB and the top of physical memory (up to 64TB). The 2168 virtual address will be randomized from 16MB up to 1GB (9 bits 2169 of entropy). Note that this also reduces the memory space 2170 available to kernel modules from 1.5GB to 1GB. 2171 2172 On 32-bit, the kernel physical and virtual addresses are 2173 randomized together. They will be randomized from 16MB up to 2174 512MB (8 bits of entropy). 2175 2176 Entropy is generated using the RDRAND instruction if it is 2177 supported. If RDTSC is supported, its value is mixed into 2178 the entropy pool as well. If neither RDRAND nor RDTSC are 2179 supported, then entropy is read from the i8254 timer. The 2180 usable entropy is limited by the kernel being built using 2181 2GB addressing, and that PHYSICAL_ALIGN must be at a 2182 minimum of 2MB. As a result, only 10 bits of entropy are 2183 theoretically possible, but the implementations are further 2184 limited due to memory layouts. 2185 2186 If unsure, say Y. 2187 2188# Relocation on x86 needs some additional build support 2189config X86_NEED_RELOCS 2190 def_bool y 2191 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2192 2193config PHYSICAL_ALIGN 2194 hex "Alignment value to which kernel should be aligned" 2195 default "0x200000" 2196 range 0x2000 0x1000000 if X86_32 2197 range 0x200000 0x1000000 if X86_64 2198 help 2199 This value puts the alignment restrictions on physical address 2200 where kernel is loaded and run from. Kernel is compiled for an 2201 address which meets above alignment restriction. 2202 2203 If bootloader loads the kernel at a non-aligned address and 2204 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2205 address aligned to above value and run from there. 2206 2207 If bootloader loads the kernel at a non-aligned address and 2208 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2209 load address and decompress itself to the address it has been 2210 compiled for and run from there. The address for which kernel is 2211 compiled already meets above alignment restrictions. Hence the 2212 end result is that kernel runs from a physical address meeting 2213 above alignment restrictions. 2214 2215 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2216 this value must be a multiple of 0x200000. 2217 2218 Don't change this unless you know what you are doing. 2219 2220config DYNAMIC_MEMORY_LAYOUT 2221 bool 2222 help 2223 This option makes base addresses of vmalloc and vmemmap as well as 2224 __PAGE_OFFSET movable during boot. 2225 2226config RANDOMIZE_MEMORY 2227 bool "Randomize the kernel memory sections" 2228 depends on X86_64 2229 depends on RANDOMIZE_BASE 2230 select DYNAMIC_MEMORY_LAYOUT 2231 default RANDOMIZE_BASE 2232 help 2233 Randomizes the base virtual address of kernel memory sections 2234 (physical memory mapping, vmalloc & vmemmap). This security feature 2235 makes exploits relying on predictable memory locations less reliable. 2236 2237 The order of allocations remains unchanged. Entropy is generated in 2238 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2239 configuration have in average 30,000 different possible virtual 2240 addresses for each memory section. 2241 2242 If unsure, say Y. 2243 2244config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2245 hex "Physical memory mapping padding" if EXPERT 2246 depends on RANDOMIZE_MEMORY 2247 default "0xa" if MEMORY_HOTPLUG 2248 default "0x0" 2249 range 0x1 0x40 if MEMORY_HOTPLUG 2250 range 0x0 0x40 2251 help 2252 Define the padding in terabytes added to the existing physical 2253 memory size during kernel memory randomization. It is useful 2254 for memory hotplug support but reduces the entropy available for 2255 address randomization. 2256 2257 If unsure, leave at the default value. 2258 2259config ADDRESS_MASKING 2260 bool "Linear Address Masking support" 2261 depends on X86_64 2262 help 2263 Linear Address Masking (LAM) modifies the checking that is applied 2264 to 64-bit linear addresses, allowing software to use of the 2265 untranslated address bits for metadata. 2266 2267 The capability can be used for efficient address sanitizers (ASAN) 2268 implementation and for optimizations in JITs. 2269 2270config HOTPLUG_CPU 2271 def_bool y 2272 depends on SMP 2273 2274config COMPAT_VDSO 2275 def_bool n 2276 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2277 depends on COMPAT_32 2278 help 2279 Certain buggy versions of glibc will crash if they are 2280 presented with a 32-bit vDSO that is not mapped at the address 2281 indicated in its segment table. 2282 2283 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2284 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2285 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2286 the only released version with the bug, but OpenSUSE 9 2287 contains a buggy "glibc 2.3.2". 2288 2289 The symptom of the bug is that everything crashes on startup, saying: 2290 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2291 2292 Saying Y here changes the default value of the vdso32 boot 2293 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2294 This works around the glibc bug but hurts performance. 2295 2296 If unsure, say N: if you are compiling your own kernel, you 2297 are unlikely to be using a buggy version of glibc. 2298 2299choice 2300 prompt "vsyscall table for legacy applications" 2301 depends on X86_64 2302 default LEGACY_VSYSCALL_XONLY 2303 help 2304 Legacy user code that does not know how to find the vDSO expects 2305 to be able to issue three syscalls by calling fixed addresses in 2306 kernel space. Since this location is not randomized with ASLR, 2307 it can be used to assist security vulnerability exploitation. 2308 2309 This setting can be changed at boot time via the kernel command 2310 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2311 is deprecated and can only be enabled using the kernel command 2312 line. 2313 2314 On a system with recent enough glibc (2.14 or newer) and no 2315 static binaries, you can say None without a performance penalty 2316 to improve security. 2317 2318 If unsure, select "Emulate execution only". 2319 2320 config LEGACY_VSYSCALL_XONLY 2321 bool "Emulate execution only" 2322 help 2323 The kernel traps and emulates calls into the fixed vsyscall 2324 address mapping and does not allow reads. This 2325 configuration is recommended when userspace might use the 2326 legacy vsyscall area but support for legacy binary 2327 instrumentation of legacy code is not needed. It mitigates 2328 certain uses of the vsyscall area as an ASLR-bypassing 2329 buffer. 2330 2331 config LEGACY_VSYSCALL_NONE 2332 bool "None" 2333 help 2334 There will be no vsyscall mapping at all. This will 2335 eliminate any risk of ASLR bypass due to the vsyscall 2336 fixed address mapping. Attempts to use the vsyscalls 2337 will be reported to dmesg, so that either old or 2338 malicious userspace programs can be identified. 2339 2340endchoice 2341 2342config CMDLINE_BOOL 2343 bool "Built-in kernel command line" 2344 help 2345 Allow for specifying boot arguments to the kernel at 2346 build time. On some systems (e.g. embedded ones), it is 2347 necessary or convenient to provide some or all of the 2348 kernel boot arguments with the kernel itself (that is, 2349 to not rely on the boot loader to provide them.) 2350 2351 To compile command line arguments into the kernel, 2352 set this option to 'Y', then fill in the 2353 boot arguments in CONFIG_CMDLINE. 2354 2355 Systems with fully functional boot loaders (i.e. non-embedded) 2356 should leave this option set to 'N'. 2357 2358config CMDLINE 2359 string "Built-in kernel command string" 2360 depends on CMDLINE_BOOL 2361 default "" 2362 help 2363 Enter arguments here that should be compiled into the kernel 2364 image and used at boot time. If the boot loader provides a 2365 command line at boot time, it is appended to this string to 2366 form the full kernel command line, when the system boots. 2367 2368 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2369 change this behavior. 2370 2371 In most cases, the command line (whether built-in or provided 2372 by the boot loader) should specify the device for the root 2373 file system. 2374 2375config CMDLINE_OVERRIDE 2376 bool "Built-in command line overrides boot loader arguments" 2377 depends on CMDLINE_BOOL && CMDLINE != "" 2378 help 2379 Set this option to 'Y' to have the kernel ignore the boot loader 2380 command line, and use ONLY the built-in command line. 2381 2382 This is used to work around broken boot loaders. This should 2383 be set to 'N' under normal conditions. 2384 2385config MODIFY_LDT_SYSCALL 2386 bool "Enable the LDT (local descriptor table)" if EXPERT 2387 default y 2388 help 2389 Linux can allow user programs to install a per-process x86 2390 Local Descriptor Table (LDT) using the modify_ldt(2) system 2391 call. This is required to run 16-bit or segmented code such as 2392 DOSEMU or some Wine programs. It is also used by some very old 2393 threading libraries. 2394 2395 Enabling this feature adds a small amount of overhead to 2396 context switches and increases the low-level kernel attack 2397 surface. Disabling it removes the modify_ldt(2) system call. 2398 2399 Saying 'N' here may make sense for embedded or server kernels. 2400 2401config STRICT_SIGALTSTACK_SIZE 2402 bool "Enforce strict size checking for sigaltstack" 2403 depends on DYNAMIC_SIGFRAME 2404 help 2405 For historical reasons MINSIGSTKSZ is a constant which became 2406 already too small with AVX512 support. Add a mechanism to 2407 enforce strict checking of the sigaltstack size against the 2408 real size of the FPU frame. This option enables the check 2409 by default. It can also be controlled via the kernel command 2410 line option 'strict_sas_size' independent of this config 2411 switch. Enabling it might break existing applications which 2412 allocate a too small sigaltstack but 'work' because they 2413 never get a signal delivered. 2414 2415 Say 'N' unless you want to really enforce this check. 2416 2417config CFI_AUTO_DEFAULT 2418 bool "Attempt to use FineIBT by default at boot time" 2419 depends on FINEIBT 2420 default y 2421 help 2422 Attempt to use FineIBT by default at boot time. If enabled, 2423 this is the same as booting with "cfi=auto". If disabled, 2424 this is the same as booting with "cfi=kcfi". 2425 2426source "kernel/livepatch/Kconfig" 2427 2428endmenu 2429 2430config CC_HAS_NAMED_AS 2431 def_bool CC_IS_GCC && GCC_VERSION >= 90100 2432 2433config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2434 def_bool CC_IS_GCC && GCC_VERSION >= 130300 2435 2436config USE_X86_SEG_SUPPORT 2437 def_bool y 2438 depends on CC_HAS_NAMED_AS 2439 # 2440 # -fsanitize=kernel-address (KASAN) and -fsanitize=thread 2441 # (KCSAN) are incompatible with named address spaces with 2442 # GCC < 13.3 - see GCC PR sanitizer/111736. 2443 # 2444 depends on !(KASAN || KCSAN) || CC_HAS_NAMED_AS_FIXED_SANITIZERS 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