1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select HAVE_ARCH_SOFT_DIRTY 32 select MODULES_USE_ELF_RELA 33 select NEED_DMA_MAP_STATE 34 select SWIOTLB 35 select ARCH_HAS_ELFCORE_COMPAT 36 select ZONE_DMA32 37 38config FORCE_DYNAMIC_FTRACE 39 def_bool y 40 depends on X86_32 41 depends on FUNCTION_TRACER 42 select DYNAMIC_FTRACE 43 help 44 We keep the static function tracing (!DYNAMIC_FTRACE) around 45 in order to test the non static function tracing in the 46 generic code, as other architectures still use it. But we 47 only need to keep it around for x86_64. No need to keep it 48 for x86_32. For x86_32, force DYNAMIC_FTRACE. 49# 50# Arch settings 51# 52# ( Note that options that are marked 'if X86_64' could in principle be 53# ported to 32-bit as well. ) 54# 55config X86 56 def_bool y 57 # 58 # Note: keep this list sorted alphabetically 59 # 60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 62 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 63 select ARCH_32BIT_OFF_T if X86_32 64 select ARCH_CLOCKSOURCE_INIT 65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 72 select ARCH_HAS_CACHE_LINE_SIZE 73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 74 select ARCH_HAS_CPU_FINALIZE_INIT 75 select ARCH_HAS_CPU_PASID if IOMMU_SVA 76 select ARCH_HAS_CURRENT_STACK_POINTER 77 select ARCH_HAS_DEBUG_VIRTUAL 78 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 79 select ARCH_HAS_DEVMEM_IS_ALLOWED 80 select ARCH_HAS_EARLY_DEBUG if KGDB 81 select ARCH_HAS_ELF_RANDOMIZE 82 select ARCH_HAS_FAST_MULTIPLIER 83 select ARCH_HAS_FORTIFY_SOURCE 84 select ARCH_HAS_GCOV_PROFILE_ALL 85 select ARCH_HAS_KCOV if X86_64 86 select ARCH_HAS_MEM_ENCRYPT 87 select ARCH_HAS_MEMBARRIER_SYNC_CORE 88 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 89 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 90 select ARCH_HAS_PMEM_API if X86_64 91 select ARCH_HAS_PTE_DEVMAP if X86_64 92 select ARCH_HAS_PTE_SPECIAL 93 select ARCH_HAS_HW_PTE_YOUNG 94 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 95 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 96 select ARCH_HAS_COPY_MC if X86_64 97 select ARCH_HAS_SET_MEMORY 98 select ARCH_HAS_SET_DIRECT_MAP 99 select ARCH_HAS_STRICT_KERNEL_RWX 100 select ARCH_HAS_STRICT_MODULE_RWX 101 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 102 select ARCH_HAS_SYSCALL_WRAPPER 103 select ARCH_HAS_UBSAN 104 select ARCH_HAS_DEBUG_WX 105 select ARCH_HAS_ZONE_DMA_SET if EXPERT 106 select ARCH_HAVE_NMI_SAFE_CMPXCHG 107 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 108 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 109 select ARCH_MIGHT_HAVE_PC_PARPORT 110 select ARCH_MIGHT_HAVE_PC_SERIO 111 select ARCH_STACKWALK 112 select ARCH_SUPPORTS_ACPI 113 select ARCH_SUPPORTS_ATOMIC_RMW 114 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 115 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 116 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 117 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 118 select ARCH_SUPPORTS_CFI_CLANG if X86_64 119 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 120 select ARCH_SUPPORTS_LTO_CLANG 121 select ARCH_SUPPORTS_LTO_CLANG_THIN 122 select ARCH_USE_BUILTIN_BSWAP 123 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64 124 select ARCH_USE_MEMTEST 125 select ARCH_USE_QUEUED_RWLOCKS 126 select ARCH_USE_QUEUED_SPINLOCKS 127 select ARCH_USE_SYM_ANNOTATIONS 128 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 129 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 130 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 131 select ARCH_WANTS_NO_INSTR 132 select ARCH_WANT_GENERAL_HUGETLB 133 select ARCH_WANT_HUGE_PMD_SHARE 134 select ARCH_WANT_LD_ORPHAN_WARN 135 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 136 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 137 select ARCH_WANTS_THP_SWAP if X86_64 138 select ARCH_HAS_PARANOID_L1D_FLUSH 139 select BUILDTIME_TABLE_SORT 140 select CLKEVT_I8253 141 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 142 select CLOCKSOURCE_WATCHDOG 143 # Word-size accesses may read uninitialized data past the trailing \0 144 # in strings and cause false KMSAN reports. 145 select DCACHE_WORD_ACCESS if !KMSAN 146 select DYNAMIC_SIGFRAME 147 select EDAC_ATOMIC_SCRUB 148 select EDAC_SUPPORT 149 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 150 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 151 select GENERIC_CLOCKEVENTS_MIN_ADJUST 152 select GENERIC_CMOS_UPDATE 153 select GENERIC_CPU_AUTOPROBE 154 select GENERIC_CPU_DEVICES 155 select GENERIC_CPU_VULNERABILITIES 156 select GENERIC_EARLY_IOREMAP 157 select GENERIC_ENTRY 158 select GENERIC_IOMAP 159 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 160 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 161 select GENERIC_IRQ_MIGRATION if SMP 162 select GENERIC_IRQ_PROBE 163 select GENERIC_IRQ_RESERVATION_MODE 164 select GENERIC_IRQ_SHOW 165 select GENERIC_PENDING_IRQ if SMP 166 select GENERIC_PTDUMP 167 select GENERIC_SMP_IDLE_THREAD 168 select GENERIC_TIME_VSYSCALL 169 select GENERIC_GETTIMEOFDAY 170 select GENERIC_VDSO_TIME_NS 171 select GUP_GET_PXX_LOW_HIGH if X86_PAE 172 select HARDIRQS_SW_RESEND 173 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 174 select HAS_IOPORT 175 select HAVE_ACPI_APEI if ACPI 176 select HAVE_ACPI_APEI_NMI if ACPI 177 select HAVE_ALIGNED_STRUCT_PAGE 178 select HAVE_ARCH_AUDITSYSCALL 179 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 180 select HAVE_ARCH_HUGE_VMALLOC if X86_64 181 select HAVE_ARCH_JUMP_LABEL 182 select HAVE_ARCH_JUMP_LABEL_RELATIVE 183 select HAVE_ARCH_KASAN if X86_64 184 select HAVE_ARCH_KASAN_VMALLOC if X86_64 185 select HAVE_ARCH_KFENCE 186 select HAVE_ARCH_KMSAN if X86_64 187 select HAVE_ARCH_KGDB 188 select HAVE_ARCH_MMAP_RND_BITS if MMU 189 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 190 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 191 select HAVE_ARCH_PREL32_RELOCATIONS 192 select HAVE_ARCH_SECCOMP_FILTER 193 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 194 select HAVE_ARCH_STACKLEAK 195 select HAVE_ARCH_TRACEHOOK 196 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 197 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 198 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 199 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 200 select HAVE_ARCH_VMAP_STACK if X86_64 201 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 202 select HAVE_ARCH_WITHIN_STACK_FRAMES 203 select HAVE_ASM_MODVERSIONS 204 select HAVE_CMPXCHG_DOUBLE 205 select HAVE_CMPXCHG_LOCAL 206 select HAVE_CONTEXT_TRACKING_USER if X86_64 207 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 208 select HAVE_C_RECORDMCOUNT 209 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 210 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 211 select HAVE_BUILDTIME_MCOUNT_SORT 212 select HAVE_DEBUG_KMEMLEAK 213 select HAVE_DMA_CONTIGUOUS 214 select HAVE_DYNAMIC_FTRACE 215 select HAVE_DYNAMIC_FTRACE_WITH_REGS 216 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 217 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 218 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 219 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 220 select HAVE_EBPF_JIT 221 select HAVE_EFFICIENT_UNALIGNED_ACCESS 222 select HAVE_EISA 223 select HAVE_EXIT_THREAD 224 select HAVE_FAST_GUP 225 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 226 select HAVE_FTRACE_MCOUNT_RECORD 227 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 228 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 229 select HAVE_FUNCTION_TRACER 230 select HAVE_GCC_PLUGINS 231 select HAVE_HW_BREAKPOINT 232 select HAVE_IOREMAP_PROT 233 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 234 select HAVE_IRQ_TIME_ACCOUNTING 235 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 236 select HAVE_KERNEL_BZIP2 237 select HAVE_KERNEL_GZIP 238 select HAVE_KERNEL_LZ4 239 select HAVE_KERNEL_LZMA 240 select HAVE_KERNEL_LZO 241 select HAVE_KERNEL_XZ 242 select HAVE_KERNEL_ZSTD 243 select HAVE_KPROBES 244 select HAVE_KPROBES_ON_FTRACE 245 select HAVE_FUNCTION_ERROR_INJECTION 246 select HAVE_KRETPROBES 247 select HAVE_RETHOOK 248 select HAVE_LIVEPATCH if X86_64 249 select HAVE_MIXED_BREAKPOINTS_REGS 250 select HAVE_MOD_ARCH_SPECIFIC 251 select HAVE_MOVE_PMD 252 select HAVE_MOVE_PUD 253 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 254 select HAVE_NMI 255 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 256 select HAVE_OBJTOOL if X86_64 257 select HAVE_OPTPROBES 258 select HAVE_PAGE_SIZE_4KB 259 select HAVE_PCSPKR_PLATFORM 260 select HAVE_PERF_EVENTS 261 select HAVE_PERF_EVENTS_NMI 262 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 263 select HAVE_PCI 264 select HAVE_PERF_REGS 265 select HAVE_PERF_USER_STACK_DUMP 266 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 267 select MMU_GATHER_MERGE_VMAS 268 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 269 select HAVE_REGS_AND_STACK_ACCESS_API 270 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 271 select HAVE_FUNCTION_ARG_ACCESS_API 272 select HAVE_SETUP_PER_CPU_AREA 273 select HAVE_SOFTIRQ_ON_OWN_STACK 274 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 275 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 276 select HAVE_STATIC_CALL 277 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 278 select HAVE_PREEMPT_DYNAMIC_CALL 279 select HAVE_RSEQ 280 select HAVE_RUST if X86_64 281 select HAVE_SYSCALL_TRACEPOINTS 282 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 283 select HAVE_UNSTABLE_SCHED_CLOCK 284 select HAVE_USER_RETURN_NOTIFIER 285 select HAVE_GENERIC_VDSO 286 select HOTPLUG_PARALLEL if SMP && X86_64 287 select HOTPLUG_SMT if SMP 288 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 289 select IRQ_FORCED_THREADING 290 select LOCK_MM_AND_FIND_VMA 291 select NEED_PER_CPU_EMBED_FIRST_CHUNK 292 select NEED_PER_CPU_PAGE_FIRST_CHUNK 293 select NEED_SG_DMA_LENGTH 294 select PCI_DOMAINS if PCI 295 select PCI_LOCKLESS_CONFIG if PCI 296 select PERF_EVENTS 297 select RTC_LIB 298 select RTC_MC146818_LIB 299 select SPARSE_IRQ 300 select SYSCTL_EXCEPTION_TRACE 301 select THREAD_INFO_IN_TASK 302 select TRACE_IRQFLAGS_SUPPORT 303 select TRACE_IRQFLAGS_NMI_SUPPORT 304 select USER_STACKTRACE_SUPPORT 305 select HAVE_ARCH_KCSAN if X86_64 306 select PROC_PID_ARCH_STATUS if PROC_FS 307 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 308 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 309 select FUNCTION_ALIGNMENT_4B 310 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 311 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 312 313config INSTRUCTION_DECODER 314 def_bool y 315 depends on KPROBES || PERF_EVENTS || UPROBES 316 317config OUTPUT_FORMAT 318 string 319 default "elf32-i386" if X86_32 320 default "elf64-x86-64" if X86_64 321 322config LOCKDEP_SUPPORT 323 def_bool y 324 325config STACKTRACE_SUPPORT 326 def_bool y 327 328config MMU 329 def_bool y 330 331config ARCH_MMAP_RND_BITS_MIN 332 default 28 if 64BIT 333 default 8 334 335config ARCH_MMAP_RND_BITS_MAX 336 default 32 if 64BIT 337 default 16 338 339config ARCH_MMAP_RND_COMPAT_BITS_MIN 340 default 8 341 342config ARCH_MMAP_RND_COMPAT_BITS_MAX 343 default 16 344 345config SBUS 346 bool 347 348config GENERIC_ISA_DMA 349 def_bool y 350 depends on ISA_DMA_API 351 352config GENERIC_CSUM 353 bool 354 default y if KMSAN || KASAN 355 356config GENERIC_BUG 357 def_bool y 358 depends on BUG 359 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 360 361config GENERIC_BUG_RELATIVE_POINTERS 362 bool 363 364config ARCH_MAY_HAVE_PC_FDC 365 def_bool y 366 depends on ISA_DMA_API 367 368config GENERIC_CALIBRATE_DELAY 369 def_bool y 370 371config ARCH_HAS_CPU_RELAX 372 def_bool y 373 374config ARCH_HIBERNATION_POSSIBLE 375 def_bool y 376 377config ARCH_SUSPEND_POSSIBLE 378 def_bool y 379 380config AUDIT_ARCH 381 def_bool y if X86_64 382 383config KASAN_SHADOW_OFFSET 384 hex 385 depends on KASAN 386 default 0xdffffc0000000000 387 388config HAVE_INTEL_TXT 389 def_bool y 390 depends on INTEL_IOMMU && ACPI 391 392config X86_64_SMP 393 def_bool y 394 depends on X86_64 && SMP 395 396config ARCH_SUPPORTS_UPROBES 397 def_bool y 398 399config FIX_EARLYCON_MEM 400 def_bool y 401 402config DYNAMIC_PHYSICAL_MASK 403 bool 404 405config PGTABLE_LEVELS 406 int 407 default 5 if X86_5LEVEL 408 default 4 if X86_64 409 default 3 if X86_PAE 410 default 2 411 412config CC_HAS_SANE_STACKPROTECTOR 413 bool 414 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 415 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 416 help 417 We have to make sure stack protector is unconditionally disabled if 418 the compiler produces broken code or if it does not let us control 419 the segment on 32-bit kernels. 420 421menu "Processor type and features" 422 423config SMP 424 bool "Symmetric multi-processing support" 425 help 426 This enables support for systems with more than one CPU. If you have 427 a system with only one CPU, say N. If you have a system with more 428 than one CPU, say Y. 429 430 If you say N here, the kernel will run on uni- and multiprocessor 431 machines, but will use only one CPU of a multiprocessor machine. If 432 you say Y here, the kernel will run on many, but not all, 433 uniprocessor machines. On a uniprocessor machine, the kernel 434 will run faster if you say N here. 435 436 Note that if you say Y here and choose architecture "586" or 437 "Pentium" under "Processor family", the kernel will not work on 486 438 architectures. Similarly, multiprocessor kernels for the "PPro" 439 architecture may not work on all Pentium based boards. 440 441 People using multiprocessor machines who say Y here should also say 442 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 443 Management" code will be disabled if you say Y here. 444 445 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 446 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 447 <http://www.tldp.org/docs.html#howto>. 448 449 If you don't know what to do here, say N. 450 451config X86_X2APIC 452 bool "Support x2apic" 453 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 454 help 455 This enables x2apic support on CPUs that have this feature. 456 457 This allows 32-bit apic IDs (so it can support very large systems), 458 and accesses the local apic via MSRs not via mmio. 459 460 Some Intel systems circa 2022 and later are locked into x2APIC mode 461 and can not fall back to the legacy APIC modes if SGX or TDX are 462 enabled in the BIOS. They will boot with very reduced functionality 463 without enabling this option. 464 465 If you don't know what to do here, say N. 466 467config X86_MPPARSE 468 bool "Enable MPS table" if ACPI 469 default y 470 depends on X86_LOCAL_APIC 471 help 472 For old smp systems that do not have proper acpi support. Newer systems 473 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 474 475config GOLDFISH 476 def_bool y 477 depends on X86_GOLDFISH 478 479config X86_CPU_RESCTRL 480 bool "x86 CPU resource control support" 481 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 482 select KERNFS 483 select PROC_CPU_RESCTRL if PROC_FS 484 help 485 Enable x86 CPU resource control support. 486 487 Provide support for the allocation and monitoring of system resources 488 usage by the CPU. 489 490 Intel calls this Intel Resource Director Technology 491 (Intel(R) RDT). More information about RDT can be found in the 492 Intel x86 Architecture Software Developer Manual. 493 494 AMD calls this AMD Platform Quality of Service (AMD QoS). 495 More information about AMD QoS can be found in the AMD64 Technology 496 Platform Quality of Service Extensions manual. 497 498 Say N if unsure. 499 500config X86_FRED 501 bool "Flexible Return and Event Delivery" 502 depends on X86_64 503 help 504 When enabled, try to use Flexible Return and Event Delivery 505 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 506 ring transitions and exception/interrupt handling if the 507 system supports. 508 509if X86_32 510config X86_BIGSMP 511 bool "Support for big SMP systems with more than 8 CPUs" 512 depends on SMP 513 help 514 This option is needed for the systems that have more than 8 CPUs. 515 516config X86_EXTENDED_PLATFORM 517 bool "Support for extended (non-PC) x86 platforms" 518 default y 519 help 520 If you disable this option then the kernel will only support 521 standard PC platforms. (which covers the vast majority of 522 systems out there.) 523 524 If you enable this option then you'll be able to select support 525 for the following (non-PC) 32 bit x86 platforms: 526 Goldfish (Android emulator) 527 AMD Elan 528 RDC R-321x SoC 529 SGI 320/540 (Visual Workstation) 530 STA2X11-based (e.g. Northville) 531 Moorestown MID devices 532 533 If you have one of these systems, or if you want to build a 534 generic distribution kernel, say Y here - otherwise say N. 535endif # X86_32 536 537if X86_64 538config X86_EXTENDED_PLATFORM 539 bool "Support for extended (non-PC) x86 platforms" 540 default y 541 help 542 If you disable this option then the kernel will only support 543 standard PC platforms. (which covers the vast majority of 544 systems out there.) 545 546 If you enable this option then you'll be able to select support 547 for the following (non-PC) 64 bit x86 platforms: 548 Numascale NumaChip 549 ScaleMP vSMP 550 SGI Ultraviolet 551 552 If you have one of these systems, or if you want to build a 553 generic distribution kernel, say Y here - otherwise say N. 554endif # X86_64 555# This is an alphabetically sorted list of 64 bit extended platforms 556# Please maintain the alphabetic order if and when there are additions 557config X86_NUMACHIP 558 bool "Numascale NumaChip" 559 depends on X86_64 560 depends on X86_EXTENDED_PLATFORM 561 depends on NUMA 562 depends on SMP 563 depends on X86_X2APIC 564 depends on PCI_MMCONFIG 565 help 566 Adds support for Numascale NumaChip large-SMP systems. Needed to 567 enable more than ~168 cores. 568 If you don't have one of these, you should say N here. 569 570config X86_VSMP 571 bool "ScaleMP vSMP" 572 select HYPERVISOR_GUEST 573 select PARAVIRT 574 depends on X86_64 && PCI 575 depends on X86_EXTENDED_PLATFORM 576 depends on SMP 577 help 578 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 579 supposed to run on these EM64T-based machines. Only choose this option 580 if you have one of these machines. 581 582config X86_UV 583 bool "SGI Ultraviolet" 584 depends on X86_64 585 depends on X86_EXTENDED_PLATFORM 586 depends on NUMA 587 depends on EFI 588 depends on KEXEC_CORE 589 depends on X86_X2APIC 590 depends on PCI 591 help 592 This option is needed in order to support SGI Ultraviolet systems. 593 If you don't have one of these, you should say N here. 594 595# Following is an alphabetically sorted list of 32 bit extended platforms 596# Please maintain the alphabetic order if and when there are additions 597 598config X86_GOLDFISH 599 bool "Goldfish (Virtual Platform)" 600 depends on X86_EXTENDED_PLATFORM 601 help 602 Enable support for the Goldfish virtual platform used primarily 603 for Android development. Unless you are building for the Android 604 Goldfish emulator say N here. 605 606config X86_INTEL_CE 607 bool "CE4100 TV platform" 608 depends on PCI 609 depends on PCI_GODIRECT 610 depends on X86_IO_APIC 611 depends on X86_32 612 depends on X86_EXTENDED_PLATFORM 613 select X86_REBOOTFIXUPS 614 select OF 615 select OF_EARLY_FLATTREE 616 help 617 Select for the Intel CE media processor (CE4100) SOC. 618 This option compiles in support for the CE4100 SOC for settop 619 boxes and media devices. 620 621config X86_INTEL_MID 622 bool "Intel MID platform support" 623 depends on X86_EXTENDED_PLATFORM 624 depends on X86_PLATFORM_DEVICES 625 depends on PCI 626 depends on X86_64 || (PCI_GOANY && X86_32) 627 depends on X86_IO_APIC 628 select I2C 629 select DW_APB_TIMER 630 select INTEL_SCU_PCI 631 help 632 Select to build a kernel capable of supporting Intel MID (Mobile 633 Internet Device) platform systems which do not have the PCI legacy 634 interfaces. If you are building for a PC class system say N here. 635 636 Intel MID platforms are based on an Intel processor and chipset which 637 consume less power than most of the x86 derivatives. 638 639config X86_INTEL_QUARK 640 bool "Intel Quark platform support" 641 depends on X86_32 642 depends on X86_EXTENDED_PLATFORM 643 depends on X86_PLATFORM_DEVICES 644 depends on X86_TSC 645 depends on PCI 646 depends on PCI_GOANY 647 depends on X86_IO_APIC 648 select IOSF_MBI 649 select INTEL_IMR 650 select COMMON_CLK 651 help 652 Select to include support for Quark X1000 SoC. 653 Say Y here if you have a Quark based system such as the Arduino 654 compatible Intel Galileo. 655 656config X86_INTEL_LPSS 657 bool "Intel Low Power Subsystem Support" 658 depends on X86 && ACPI && PCI 659 select COMMON_CLK 660 select PINCTRL 661 select IOSF_MBI 662 help 663 Select to build support for Intel Low Power Subsystem such as 664 found on Intel Lynxpoint PCH. Selecting this option enables 665 things like clock tree (common clock framework) and pincontrol 666 which are needed by the LPSS peripheral drivers. 667 668config X86_AMD_PLATFORM_DEVICE 669 bool "AMD ACPI2Platform devices support" 670 depends on ACPI 671 select COMMON_CLK 672 select PINCTRL 673 help 674 Select to interpret AMD specific ACPI device to platform device 675 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 676 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 677 implemented under PINCTRL subsystem. 678 679config IOSF_MBI 680 tristate "Intel SoC IOSF Sideband support for SoC platforms" 681 depends on PCI 682 help 683 This option enables sideband register access support for Intel SoC 684 platforms. On these platforms the IOSF sideband is used in lieu of 685 MSR's for some register accesses, mostly but not limited to thermal 686 and power. Drivers may query the availability of this device to 687 determine if they need the sideband in order to work on these 688 platforms. The sideband is available on the following SoC products. 689 This list is not meant to be exclusive. 690 - BayTrail 691 - Braswell 692 - Quark 693 694 You should say Y if you are running a kernel on one of these SoC's. 695 696config IOSF_MBI_DEBUG 697 bool "Enable IOSF sideband access through debugfs" 698 depends on IOSF_MBI && DEBUG_FS 699 help 700 Select this option to expose the IOSF sideband access registers (MCR, 701 MDR, MCRX) through debugfs to write and read register information from 702 different units on the SoC. This is most useful for obtaining device 703 state information for debug and analysis. As this is a general access 704 mechanism, users of this option would have specific knowledge of the 705 device they want to access. 706 707 If you don't require the option or are in doubt, say N. 708 709config X86_RDC321X 710 bool "RDC R-321x SoC" 711 depends on X86_32 712 depends on X86_EXTENDED_PLATFORM 713 select M486 714 select X86_REBOOTFIXUPS 715 help 716 This option is needed for RDC R-321x system-on-chip, also known 717 as R-8610-(G). 718 If you don't have one of these chips, you should say N here. 719 720config X86_32_NON_STANDARD 721 bool "Support non-standard 32-bit SMP architectures" 722 depends on X86_32 && SMP 723 depends on X86_EXTENDED_PLATFORM 724 help 725 This option compiles in the bigsmp and STA2X11 default 726 subarchitectures. It is intended for a generic binary 727 kernel. If you select them all, kernel will probe it one by 728 one and will fallback to default. 729 730# Alphabetically sorted list of Non standard 32 bit platforms 731 732config X86_SUPPORTS_MEMORY_FAILURE 733 def_bool y 734 # MCE code calls memory_failure(): 735 depends on X86_MCE 736 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 737 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 738 depends on X86_64 || !SPARSEMEM 739 select ARCH_SUPPORTS_MEMORY_FAILURE 740 741config STA2X11 742 bool "STA2X11 Companion Chip Support" 743 depends on X86_32_NON_STANDARD && PCI 744 select SWIOTLB 745 select MFD_STA2X11 746 select GPIOLIB 747 help 748 This adds support for boards based on the STA2X11 IO-Hub, 749 a.k.a. "ConneXt". The chip is used in place of the standard 750 PC chipset, so all "standard" peripherals are missing. If this 751 option is selected the kernel will still be able to boot on 752 standard PC machines. 753 754config X86_32_IRIS 755 tristate "Eurobraille/Iris poweroff module" 756 depends on X86_32 757 help 758 The Iris machines from EuroBraille do not have APM or ACPI support 759 to shut themselves down properly. A special I/O sequence is 760 needed to do so, which is what this module does at 761 kernel shutdown. 762 763 This is only for Iris machines from EuroBraille. 764 765 If unused, say N. 766 767config SCHED_OMIT_FRAME_POINTER 768 def_bool y 769 prompt "Single-depth WCHAN output" 770 depends on X86 771 help 772 Calculate simpler /proc/<PID>/wchan values. If this option 773 is disabled then wchan values will recurse back to the 774 caller function. This provides more accurate wchan values, 775 at the expense of slightly more scheduling overhead. 776 777 If in doubt, say "Y". 778 779menuconfig HYPERVISOR_GUEST 780 bool "Linux guest support" 781 help 782 Say Y here to enable options for running Linux under various hyper- 783 visors. This option enables basic hypervisor detection and platform 784 setup. 785 786 If you say N, all options in this submenu will be skipped and 787 disabled, and Linux guest support won't be built in. 788 789if HYPERVISOR_GUEST 790 791config PARAVIRT 792 bool "Enable paravirtualization code" 793 depends on HAVE_STATIC_CALL 794 help 795 This changes the kernel so it can modify itself when it is run 796 under a hypervisor, potentially improving performance significantly 797 over full virtualization. However, when run without a hypervisor 798 the kernel is theoretically slower and slightly larger. 799 800config PARAVIRT_XXL 801 bool 802 803config PARAVIRT_DEBUG 804 bool "paravirt-ops debugging" 805 depends on PARAVIRT && DEBUG_KERNEL 806 help 807 Enable to debug paravirt_ops internals. Specifically, BUG if 808 a paravirt_op is missing when it is called. 809 810config PARAVIRT_SPINLOCKS 811 bool "Paravirtualization layer for spinlocks" 812 depends on PARAVIRT && SMP 813 help 814 Paravirtualized spinlocks allow a pvops backend to replace the 815 spinlock implementation with something virtualization-friendly 816 (for example, block the virtual CPU rather than spinning). 817 818 It has a minimal impact on native kernels and gives a nice performance 819 benefit on paravirtualized KVM / Xen kernels. 820 821 If you are unsure how to answer this question, answer Y. 822 823config X86_HV_CALLBACK_VECTOR 824 def_bool n 825 826source "arch/x86/xen/Kconfig" 827 828config KVM_GUEST 829 bool "KVM Guest support (including kvmclock)" 830 depends on PARAVIRT 831 select PARAVIRT_CLOCK 832 select ARCH_CPUIDLE_HALTPOLL 833 select X86_HV_CALLBACK_VECTOR 834 default y 835 help 836 This option enables various optimizations for running under the KVM 837 hypervisor. It includes a paravirtualized clock, so that instead 838 of relying on a PIT (or probably other) emulation by the 839 underlying device model, the host provides the guest with 840 timing infrastructure such as time of day, and system time 841 842config ARCH_CPUIDLE_HALTPOLL 843 def_bool n 844 prompt "Disable host haltpoll when loading haltpoll driver" 845 help 846 If virtualized under KVM, disable host haltpoll. 847 848config PVH 849 bool "Support for running PVH guests" 850 help 851 This option enables the PVH entry point for guest virtual machines 852 as specified in the x86/HVM direct boot ABI. 853 854config PARAVIRT_TIME_ACCOUNTING 855 bool "Paravirtual steal time accounting" 856 depends on PARAVIRT 857 help 858 Select this option to enable fine granularity task steal time 859 accounting. Time spent executing other tasks in parallel with 860 the current vCPU is discounted from the vCPU power. To account for 861 that, there can be a small performance impact. 862 863 If in doubt, say N here. 864 865config PARAVIRT_CLOCK 866 bool 867 868config JAILHOUSE_GUEST 869 bool "Jailhouse non-root cell support" 870 depends on X86_64 && PCI 871 select X86_PM_TIMER 872 help 873 This option allows to run Linux as guest in a Jailhouse non-root 874 cell. You can leave this option disabled if you only want to start 875 Jailhouse and run Linux afterwards in the root cell. 876 877config ACRN_GUEST 878 bool "ACRN Guest support" 879 depends on X86_64 880 select X86_HV_CALLBACK_VECTOR 881 help 882 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 883 a flexible, lightweight reference open-source hypervisor, built with 884 real-time and safety-criticality in mind. It is built for embedded 885 IOT with small footprint and real-time features. More details can be 886 found in https://projectacrn.org/. 887 888config INTEL_TDX_GUEST 889 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 890 depends on X86_64 && CPU_SUP_INTEL 891 depends on X86_X2APIC 892 depends on EFI_STUB 893 select ARCH_HAS_CC_PLATFORM 894 select X86_MEM_ENCRYPT 895 select X86_MCE 896 select UNACCEPTED_MEMORY 897 help 898 Support running as a guest under Intel TDX. Without this support, 899 the guest kernel can not boot or run under TDX. 900 TDX includes memory encryption and integrity capabilities 901 which protect the confidentiality and integrity of guest 902 memory contents and CPU state. TDX guests are protected from 903 some attacks from the VMM. 904 905endif # HYPERVISOR_GUEST 906 907source "arch/x86/Kconfig.cpu" 908 909config HPET_TIMER 910 def_bool X86_64 911 prompt "HPET Timer Support" if X86_32 912 help 913 Use the IA-PC HPET (High Precision Event Timer) to manage 914 time in preference to the PIT and RTC, if a HPET is 915 present. 916 HPET is the next generation timer replacing legacy 8254s. 917 The HPET provides a stable time base on SMP 918 systems, unlike the TSC, but it is more expensive to access, 919 as it is off-chip. The interface used is documented 920 in the HPET spec, revision 1. 921 922 You can safely choose Y here. However, HPET will only be 923 activated if the platform and the BIOS support this feature. 924 Otherwise the 8254 will be used for timing services. 925 926 Choose N to continue using the legacy 8254 timer. 927 928config HPET_EMULATE_RTC 929 def_bool y 930 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 931 932# Mark as expert because too many people got it wrong. 933# The code disables itself when not needed. 934config DMI 935 default y 936 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 937 bool "Enable DMI scanning" if EXPERT 938 help 939 Enabled scanning of DMI to identify machine quirks. Say Y 940 here unless you have verified that your setup is not 941 affected by entries in the DMI blacklist. Required by PNP 942 BIOS code. 943 944config GART_IOMMU 945 bool "Old AMD GART IOMMU support" 946 select DMA_OPS 947 select IOMMU_HELPER 948 select SWIOTLB 949 depends on X86_64 && PCI && AMD_NB 950 help 951 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 952 GART based hardware IOMMUs. 953 954 The GART supports full DMA access for devices with 32-bit access 955 limitations, on systems with more than 3 GB. This is usually needed 956 for USB, sound, many IDE/SATA chipsets and some other devices. 957 958 Newer systems typically have a modern AMD IOMMU, supported via 959 the CONFIG_AMD_IOMMU=y config option. 960 961 In normal configurations this driver is only active when needed: 962 there's more than 3 GB of memory and the system contains a 963 32-bit limited device. 964 965 If unsure, say Y. 966 967config BOOT_VESA_SUPPORT 968 bool 969 help 970 If true, at least one selected framebuffer driver can take advantage 971 of VESA video modes set at an early boot stage via the vga= parameter. 972 973config MAXSMP 974 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 975 depends on X86_64 && SMP && DEBUG_KERNEL 976 select CPUMASK_OFFSTACK 977 help 978 Enable maximum number of CPUS and NUMA Nodes for this architecture. 979 If unsure, say N. 980 981# 982# The maximum number of CPUs supported: 983# 984# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 985# and which can be configured interactively in the 986# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 987# 988# The ranges are different on 32-bit and 64-bit kernels, depending on 989# hardware capabilities and scalability features of the kernel. 990# 991# ( If MAXSMP is enabled we just use the highest possible value and disable 992# interactive configuration. ) 993# 994 995config NR_CPUS_RANGE_BEGIN 996 int 997 default NR_CPUS_RANGE_END if MAXSMP 998 default 1 if !SMP 999 default 2 1000 1001config NR_CPUS_RANGE_END 1002 int 1003 depends on X86_32 1004 default 64 if SMP && X86_BIGSMP 1005 default 8 if SMP && !X86_BIGSMP 1006 default 1 if !SMP 1007 1008config NR_CPUS_RANGE_END 1009 int 1010 depends on X86_64 1011 default 8192 if SMP && CPUMASK_OFFSTACK 1012 default 512 if SMP && !CPUMASK_OFFSTACK 1013 default 1 if !SMP 1014 1015config NR_CPUS_DEFAULT 1016 int 1017 depends on X86_32 1018 default 32 if X86_BIGSMP 1019 default 8 if SMP 1020 default 1 if !SMP 1021 1022config NR_CPUS_DEFAULT 1023 int 1024 depends on X86_64 1025 default 8192 if MAXSMP 1026 default 64 if SMP 1027 default 1 if !SMP 1028 1029config NR_CPUS 1030 int "Maximum number of CPUs" if SMP && !MAXSMP 1031 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1032 default NR_CPUS_DEFAULT 1033 help 1034 This allows you to specify the maximum number of CPUs which this 1035 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1036 supported value is 8192, otherwise the maximum value is 512. The 1037 minimum value which makes sense is 2. 1038 1039 This is purely to save memory: each supported CPU adds about 8KB 1040 to the kernel image. 1041 1042config SCHED_CLUSTER 1043 bool "Cluster scheduler support" 1044 depends on SMP 1045 default y 1046 help 1047 Cluster scheduler support improves the CPU scheduler's decision 1048 making when dealing with machines that have clusters of CPUs. 1049 Cluster usually means a couple of CPUs which are placed closely 1050 by sharing mid-level caches, last-level cache tags or internal 1051 busses. 1052 1053config SCHED_SMT 1054 def_bool y if SMP 1055 1056config SCHED_MC 1057 def_bool y 1058 prompt "Multi-core scheduler support" 1059 depends on SMP 1060 help 1061 Multi-core scheduler support improves the CPU scheduler's decision 1062 making when dealing with multi-core CPU chips at a cost of slightly 1063 increased overhead in some places. If unsure say N here. 1064 1065config SCHED_MC_PRIO 1066 bool "CPU core priorities scheduler support" 1067 depends on SCHED_MC 1068 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1069 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1070 select CPU_FREQ 1071 default y 1072 help 1073 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1074 core ordering determined at manufacturing time, which allows 1075 certain cores to reach higher turbo frequencies (when running 1076 single threaded workloads) than others. 1077 1078 Enabling this kernel feature teaches the scheduler about 1079 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1080 scheduler's CPU selection logic accordingly, so that higher 1081 overall system performance can be achieved. 1082 1083 This feature will have no effect on CPUs without this feature. 1084 1085 If unsure say Y here. 1086 1087config UP_LATE_INIT 1088 def_bool y 1089 depends on !SMP && X86_LOCAL_APIC 1090 1091config X86_UP_APIC 1092 bool "Local APIC support on uniprocessors" if !PCI_MSI 1093 default PCI_MSI 1094 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1095 help 1096 A local APIC (Advanced Programmable Interrupt Controller) is an 1097 integrated interrupt controller in the CPU. If you have a single-CPU 1098 system which has a processor with a local APIC, you can say Y here to 1099 enable and use it. If you say Y here even though your machine doesn't 1100 have a local APIC, then the kernel will still run with no slowdown at 1101 all. The local APIC supports CPU-generated self-interrupts (timer, 1102 performance counters), and the NMI watchdog which detects hard 1103 lockups. 1104 1105config X86_UP_IOAPIC 1106 bool "IO-APIC support on uniprocessors" 1107 depends on X86_UP_APIC 1108 help 1109 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1110 SMP-capable replacement for PC-style interrupt controllers. Most 1111 SMP systems and many recent uniprocessor systems have one. 1112 1113 If you have a single-CPU system with an IO-APIC, you can say Y here 1114 to use it. If you say Y here even though your machine doesn't have 1115 an IO-APIC, then the kernel will still run with no slowdown at all. 1116 1117config X86_LOCAL_APIC 1118 def_bool y 1119 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1120 select IRQ_DOMAIN_HIERARCHY 1121 1122config X86_IO_APIC 1123 def_bool y 1124 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1125 1126config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1127 bool "Reroute for broken boot IRQs" 1128 depends on X86_IO_APIC 1129 help 1130 This option enables a workaround that fixes a source of 1131 spurious interrupts. This is recommended when threaded 1132 interrupt handling is used on systems where the generation of 1133 superfluous "boot interrupts" cannot be disabled. 1134 1135 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1136 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1137 kernel does during interrupt handling). On chipsets where this 1138 boot IRQ generation cannot be disabled, this workaround keeps 1139 the original IRQ line masked so that only the equivalent "boot 1140 IRQ" is delivered to the CPUs. The workaround also tells the 1141 kernel to set up the IRQ handler on the boot IRQ line. In this 1142 way only one interrupt is delivered to the kernel. Otherwise 1143 the spurious second interrupt may cause the kernel to bring 1144 down (vital) interrupt lines. 1145 1146 Only affects "broken" chipsets. Interrupt sharing may be 1147 increased on these systems. 1148 1149config X86_MCE 1150 bool "Machine Check / overheating reporting" 1151 select GENERIC_ALLOCATOR 1152 default y 1153 help 1154 Machine Check support allows the processor to notify the 1155 kernel if it detects a problem (e.g. overheating, data corruption). 1156 The action the kernel takes depends on the severity of the problem, 1157 ranging from warning messages to halting the machine. 1158 1159config X86_MCELOG_LEGACY 1160 bool "Support for deprecated /dev/mcelog character device" 1161 depends on X86_MCE 1162 help 1163 Enable support for /dev/mcelog which is needed by the old mcelog 1164 userspace logging daemon. Consider switching to the new generation 1165 rasdaemon solution. 1166 1167config X86_MCE_INTEL 1168 def_bool y 1169 prompt "Intel MCE features" 1170 depends on X86_MCE && X86_LOCAL_APIC 1171 help 1172 Additional support for intel specific MCE features such as 1173 the thermal monitor. 1174 1175config X86_MCE_AMD 1176 def_bool y 1177 prompt "AMD MCE features" 1178 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1179 help 1180 Additional support for AMD specific MCE features such as 1181 the DRAM Error Threshold. 1182 1183config X86_ANCIENT_MCE 1184 bool "Support for old Pentium 5 / WinChip machine checks" 1185 depends on X86_32 && X86_MCE 1186 help 1187 Include support for machine check handling on old Pentium 5 or WinChip 1188 systems. These typically need to be enabled explicitly on the command 1189 line. 1190 1191config X86_MCE_THRESHOLD 1192 depends on X86_MCE_AMD || X86_MCE_INTEL 1193 def_bool y 1194 1195config X86_MCE_INJECT 1196 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1197 tristate "Machine check injector support" 1198 help 1199 Provide support for injecting machine checks for testing purposes. 1200 If you don't know what a machine check is and you don't do kernel 1201 QA it is safe to say n. 1202 1203source "arch/x86/events/Kconfig" 1204 1205config X86_LEGACY_VM86 1206 bool "Legacy VM86 support" 1207 depends on X86_32 1208 help 1209 This option allows user programs to put the CPU into V8086 1210 mode, which is an 80286-era approximation of 16-bit real mode. 1211 1212 Some very old versions of X and/or vbetool require this option 1213 for user mode setting. Similarly, DOSEMU will use it if 1214 available to accelerate real mode DOS programs. However, any 1215 recent version of DOSEMU, X, or vbetool should be fully 1216 functional even without kernel VM86 support, as they will all 1217 fall back to software emulation. Nevertheless, if you are using 1218 a 16-bit DOS program where 16-bit performance matters, vm86 1219 mode might be faster than emulation and you might want to 1220 enable this option. 1221 1222 Note that any app that works on a 64-bit kernel is unlikely to 1223 need this option, as 64-bit kernels don't, and can't, support 1224 V8086 mode. This option is also unrelated to 16-bit protected 1225 mode and is not needed to run most 16-bit programs under Wine. 1226 1227 Enabling this option increases the complexity of the kernel 1228 and slows down exception handling a tiny bit. 1229 1230 If unsure, say N here. 1231 1232config VM86 1233 bool 1234 default X86_LEGACY_VM86 1235 1236config X86_16BIT 1237 bool "Enable support for 16-bit segments" if EXPERT 1238 default y 1239 depends on MODIFY_LDT_SYSCALL 1240 help 1241 This option is required by programs like Wine to run 16-bit 1242 protected mode legacy code on x86 processors. Disabling 1243 this option saves about 300 bytes on i386, or around 6K text 1244 plus 16K runtime memory on x86-64, 1245 1246config X86_ESPFIX32 1247 def_bool y 1248 depends on X86_16BIT && X86_32 1249 1250config X86_ESPFIX64 1251 def_bool y 1252 depends on X86_16BIT && X86_64 1253 1254config X86_VSYSCALL_EMULATION 1255 bool "Enable vsyscall emulation" if EXPERT 1256 default y 1257 depends on X86_64 1258 help 1259 This enables emulation of the legacy vsyscall page. Disabling 1260 it is roughly equivalent to booting with vsyscall=none, except 1261 that it will also disable the helpful warning if a program 1262 tries to use a vsyscall. With this option set to N, offending 1263 programs will just segfault, citing addresses of the form 1264 0xffffffffff600?00. 1265 1266 This option is required by many programs built before 2013, and 1267 care should be used even with newer programs if set to N. 1268 1269 Disabling this option saves about 7K of kernel size and 1270 possibly 4K of additional runtime pagetable memory. 1271 1272config X86_IOPL_IOPERM 1273 bool "IOPERM and IOPL Emulation" 1274 default y 1275 help 1276 This enables the ioperm() and iopl() syscalls which are necessary 1277 for legacy applications. 1278 1279 Legacy IOPL support is an overbroad mechanism which allows user 1280 space aside of accessing all 65536 I/O ports also to disable 1281 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1282 capabilities and permission from potentially active security 1283 modules. 1284 1285 The emulation restricts the functionality of the syscall to 1286 only allowing the full range I/O port access, but prevents the 1287 ability to disable interrupts from user space which would be 1288 granted if the hardware IOPL mechanism would be used. 1289 1290config TOSHIBA 1291 tristate "Toshiba Laptop support" 1292 depends on X86_32 1293 help 1294 This adds a driver to safely access the System Management Mode of 1295 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1296 not work on models with a Phoenix BIOS. The System Management Mode 1297 is used to set the BIOS and power saving options on Toshiba portables. 1298 1299 For information on utilities to make use of this driver see the 1300 Toshiba Linux utilities web site at: 1301 <http://www.buzzard.org.uk/toshiba/>. 1302 1303 Say Y if you intend to run this kernel on a Toshiba portable. 1304 Say N otherwise. 1305 1306config X86_REBOOTFIXUPS 1307 bool "Enable X86 board specific fixups for reboot" 1308 depends on X86_32 1309 help 1310 This enables chipset and/or board specific fixups to be done 1311 in order to get reboot to work correctly. This is only needed on 1312 some combinations of hardware and BIOS. The symptom, for which 1313 this config is intended, is when reboot ends with a stalled/hung 1314 system. 1315 1316 Currently, the only fixup is for the Geode machines using 1317 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1318 1319 Say Y if you want to enable the fixup. Currently, it's safe to 1320 enable this option even if you don't need it. 1321 Say N otherwise. 1322 1323config MICROCODE 1324 def_bool y 1325 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1326 1327config MICROCODE_INITRD32 1328 def_bool y 1329 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1330 1331config MICROCODE_LATE_LOADING 1332 bool "Late microcode loading (DANGEROUS)" 1333 default n 1334 depends on MICROCODE && SMP 1335 help 1336 Loading microcode late, when the system is up and executing instructions 1337 is a tricky business and should be avoided if possible. Just the sequence 1338 of synchronizing all cores and SMT threads is one fragile dance which does 1339 not guarantee that cores might not softlock after the loading. Therefore, 1340 use this at your own risk. Late loading taints the kernel unless the 1341 microcode header indicates that it is safe for late loading via the 1342 minimal revision check. This minimal revision check can be enforced on 1343 the kernel command line with "microcode.minrev=Y". 1344 1345config MICROCODE_LATE_FORCE_MINREV 1346 bool "Enforce late microcode loading minimal revision check" 1347 default n 1348 depends on MICROCODE_LATE_LOADING 1349 help 1350 To prevent that users load microcode late which modifies already 1351 in use features, newer microcode patches have a minimum revision field 1352 in the microcode header, which tells the kernel which minimum 1353 revision must be active in the CPU to safely load that new microcode 1354 late into the running system. If disabled the check will not 1355 be enforced but the kernel will be tainted when the minimal 1356 revision check fails. 1357 1358 This minimal revision check can also be controlled via the 1359 "microcode.minrev" parameter on the kernel command line. 1360 1361 If unsure say Y. 1362 1363config X86_MSR 1364 tristate "/dev/cpu/*/msr - Model-specific register support" 1365 help 1366 This device gives privileged processes access to the x86 1367 Model-Specific Registers (MSRs). It is a character device with 1368 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1369 MSR accesses are directed to a specific CPU on multi-processor 1370 systems. 1371 1372config X86_CPUID 1373 tristate "/dev/cpu/*/cpuid - CPU information support" 1374 help 1375 This device gives processes access to the x86 CPUID instruction to 1376 be executed on a specific processor. It is a character device 1377 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1378 /dev/cpu/31/cpuid. 1379 1380choice 1381 prompt "High Memory Support" 1382 default HIGHMEM4G 1383 depends on X86_32 1384 1385config NOHIGHMEM 1386 bool "off" 1387 help 1388 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1389 However, the address space of 32-bit x86 processors is only 4 1390 Gigabytes large. That means that, if you have a large amount of 1391 physical memory, not all of it can be "permanently mapped" by the 1392 kernel. The physical memory that's not permanently mapped is called 1393 "high memory". 1394 1395 If you are compiling a kernel which will never run on a machine with 1396 more than 1 Gigabyte total physical RAM, answer "off" here (default 1397 choice and suitable for most users). This will result in a "3GB/1GB" 1398 split: 3GB are mapped so that each process sees a 3GB virtual memory 1399 space and the remaining part of the 4GB virtual memory space is used 1400 by the kernel to permanently map as much physical memory as 1401 possible. 1402 1403 If the machine has between 1 and 4 Gigabytes physical RAM, then 1404 answer "4GB" here. 1405 1406 If more than 4 Gigabytes is used then answer "64GB" here. This 1407 selection turns Intel PAE (Physical Address Extension) mode on. 1408 PAE implements 3-level paging on IA32 processors. PAE is fully 1409 supported by Linux, PAE mode is implemented on all recent Intel 1410 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1411 then the kernel will not boot on CPUs that don't support PAE! 1412 1413 The actual amount of total physical memory will either be 1414 auto detected or can be forced by using a kernel command line option 1415 such as "mem=256M". (Try "man bootparam" or see the documentation of 1416 your boot loader (lilo or loadlin) about how to pass options to the 1417 kernel at boot time.) 1418 1419 If unsure, say "off". 1420 1421config HIGHMEM4G 1422 bool "4GB" 1423 help 1424 Select this if you have a 32-bit processor and between 1 and 4 1425 gigabytes of physical RAM. 1426 1427config HIGHMEM64G 1428 bool "64GB" 1429 depends on X86_HAVE_PAE 1430 select X86_PAE 1431 help 1432 Select this if you have a 32-bit processor and more than 4 1433 gigabytes of physical RAM. 1434 1435endchoice 1436 1437choice 1438 prompt "Memory split" if EXPERT 1439 default VMSPLIT_3G 1440 depends on X86_32 1441 help 1442 Select the desired split between kernel and user memory. 1443 1444 If the address range available to the kernel is less than the 1445 physical memory installed, the remaining memory will be available 1446 as "high memory". Accessing high memory is a little more costly 1447 than low memory, as it needs to be mapped into the kernel first. 1448 Note that increasing the kernel address space limits the range 1449 available to user programs, making the address space there 1450 tighter. Selecting anything other than the default 3G/1G split 1451 will also likely make your kernel incompatible with binary-only 1452 kernel modules. 1453 1454 If you are not absolutely sure what you are doing, leave this 1455 option alone! 1456 1457 config VMSPLIT_3G 1458 bool "3G/1G user/kernel split" 1459 config VMSPLIT_3G_OPT 1460 depends on !X86_PAE 1461 bool "3G/1G user/kernel split (for full 1G low memory)" 1462 config VMSPLIT_2G 1463 bool "2G/2G user/kernel split" 1464 config VMSPLIT_2G_OPT 1465 depends on !X86_PAE 1466 bool "2G/2G user/kernel split (for full 2G low memory)" 1467 config VMSPLIT_1G 1468 bool "1G/3G user/kernel split" 1469endchoice 1470 1471config PAGE_OFFSET 1472 hex 1473 default 0xB0000000 if VMSPLIT_3G_OPT 1474 default 0x80000000 if VMSPLIT_2G 1475 default 0x78000000 if VMSPLIT_2G_OPT 1476 default 0x40000000 if VMSPLIT_1G 1477 default 0xC0000000 1478 depends on X86_32 1479 1480config HIGHMEM 1481 def_bool y 1482 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1483 1484config X86_PAE 1485 bool "PAE (Physical Address Extension) Support" 1486 depends on X86_32 && X86_HAVE_PAE 1487 select PHYS_ADDR_T_64BIT 1488 select SWIOTLB 1489 help 1490 PAE is required for NX support, and furthermore enables 1491 larger swapspace support for non-overcommit purposes. It 1492 has the cost of more pagetable lookup overhead, and also 1493 consumes more pagetable space per process. 1494 1495config X86_5LEVEL 1496 bool "Enable 5-level page tables support" 1497 default y 1498 select DYNAMIC_MEMORY_LAYOUT 1499 select SPARSEMEM_VMEMMAP 1500 depends on X86_64 1501 help 1502 5-level paging enables access to larger address space: 1503 up to 128 PiB of virtual address space and 4 PiB of 1504 physical address space. 1505 1506 It will be supported by future Intel CPUs. 1507 1508 A kernel with the option enabled can be booted on machines that 1509 support 4- or 5-level paging. 1510 1511 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1512 information. 1513 1514 Say N if unsure. 1515 1516config X86_DIRECT_GBPAGES 1517 def_bool y 1518 depends on X86_64 1519 help 1520 Certain kernel features effectively disable kernel 1521 linear 1 GB mappings (even if the CPU otherwise 1522 supports them), so don't confuse the user by printing 1523 that we have them enabled. 1524 1525config X86_CPA_STATISTICS 1526 bool "Enable statistic for Change Page Attribute" 1527 depends on DEBUG_FS 1528 help 1529 Expose statistics about the Change Page Attribute mechanism, which 1530 helps to determine the effectiveness of preserving large and huge 1531 page mappings when mapping protections are changed. 1532 1533config X86_MEM_ENCRYPT 1534 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1535 select DYNAMIC_PHYSICAL_MASK 1536 def_bool n 1537 1538config AMD_MEM_ENCRYPT 1539 bool "AMD Secure Memory Encryption (SME) support" 1540 depends on X86_64 && CPU_SUP_AMD 1541 depends on EFI_STUB 1542 select DMA_COHERENT_POOL 1543 select ARCH_USE_MEMREMAP_PROT 1544 select INSTRUCTION_DECODER 1545 select ARCH_HAS_CC_PLATFORM 1546 select X86_MEM_ENCRYPT 1547 select UNACCEPTED_MEMORY 1548 help 1549 Say yes to enable support for the encryption of system memory. 1550 This requires an AMD processor that supports Secure Memory 1551 Encryption (SME). 1552 1553# Common NUMA Features 1554config NUMA 1555 bool "NUMA Memory Allocation and Scheduler Support" 1556 depends on SMP 1557 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1558 default y if X86_BIGSMP 1559 select USE_PERCPU_NUMA_NODE_ID 1560 select OF_NUMA if OF 1561 help 1562 Enable NUMA (Non-Uniform Memory Access) support. 1563 1564 The kernel will try to allocate memory used by a CPU on the 1565 local memory controller of the CPU and add some more 1566 NUMA awareness to the kernel. 1567 1568 For 64-bit this is recommended if the system is Intel Core i7 1569 (or later), AMD Opteron, or EM64T NUMA. 1570 1571 For 32-bit this is only needed if you boot a 32-bit 1572 kernel on a 64-bit NUMA platform. 1573 1574 Otherwise, you should say N. 1575 1576config AMD_NUMA 1577 def_bool y 1578 prompt "Old style AMD Opteron NUMA detection" 1579 depends on X86_64 && NUMA && PCI 1580 help 1581 Enable AMD NUMA node topology detection. You should say Y here if 1582 you have a multi processor AMD system. This uses an old method to 1583 read the NUMA configuration directly from the builtin Northbridge 1584 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1585 which also takes priority if both are compiled in. 1586 1587config X86_64_ACPI_NUMA 1588 def_bool y 1589 prompt "ACPI NUMA detection" 1590 depends on X86_64 && NUMA && ACPI && PCI 1591 select ACPI_NUMA 1592 help 1593 Enable ACPI SRAT based node topology detection. 1594 1595config NUMA_EMU 1596 bool "NUMA emulation" 1597 depends on NUMA 1598 help 1599 Enable NUMA emulation. A flat machine will be split 1600 into virtual nodes when booted with "numa=fake=N", where N is the 1601 number of nodes. This is only useful for debugging. 1602 1603config NODES_SHIFT 1604 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1605 range 1 10 1606 default "10" if MAXSMP 1607 default "6" if X86_64 1608 default "3" 1609 depends on NUMA 1610 help 1611 Specify the maximum number of NUMA Nodes available on the target 1612 system. Increases memory reserved to accommodate various tables. 1613 1614config ARCH_FLATMEM_ENABLE 1615 def_bool y 1616 depends on X86_32 && !NUMA 1617 1618config ARCH_SPARSEMEM_ENABLE 1619 def_bool y 1620 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1621 select SPARSEMEM_STATIC if X86_32 1622 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1623 1624config ARCH_SPARSEMEM_DEFAULT 1625 def_bool X86_64 || (NUMA && X86_32) 1626 1627config ARCH_SELECT_MEMORY_MODEL 1628 def_bool y 1629 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1630 1631config ARCH_MEMORY_PROBE 1632 bool "Enable sysfs memory/probe interface" 1633 depends on MEMORY_HOTPLUG 1634 help 1635 This option enables a sysfs memory/probe interface for testing. 1636 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1637 If you are unsure how to answer this question, answer N. 1638 1639config ARCH_PROC_KCORE_TEXT 1640 def_bool y 1641 depends on X86_64 && PROC_KCORE 1642 1643config ILLEGAL_POINTER_VALUE 1644 hex 1645 default 0 if X86_32 1646 default 0xdead000000000000 if X86_64 1647 1648config X86_PMEM_LEGACY_DEVICE 1649 bool 1650 1651config X86_PMEM_LEGACY 1652 tristate "Support non-standard NVDIMMs and ADR protected memory" 1653 depends on PHYS_ADDR_T_64BIT 1654 depends on BLK_DEV 1655 select X86_PMEM_LEGACY_DEVICE 1656 select NUMA_KEEP_MEMINFO if NUMA 1657 select LIBNVDIMM 1658 help 1659 Treat memory marked using the non-standard e820 type of 12 as used 1660 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1661 The kernel will offer these regions to the 'pmem' driver so 1662 they can be used for persistent storage. 1663 1664 Say Y if unsure. 1665 1666config HIGHPTE 1667 bool "Allocate 3rd-level pagetables from highmem" 1668 depends on HIGHMEM 1669 help 1670 The VM uses one page table entry for each page of physical memory. 1671 For systems with a lot of RAM, this can be wasteful of precious 1672 low memory. Setting this option will put user-space page table 1673 entries in high memory. 1674 1675config X86_CHECK_BIOS_CORRUPTION 1676 bool "Check for low memory corruption" 1677 help 1678 Periodically check for memory corruption in low memory, which 1679 is suspected to be caused by BIOS. Even when enabled in the 1680 configuration, it is disabled at runtime. Enable it by 1681 setting "memory_corruption_check=1" on the kernel command 1682 line. By default it scans the low 64k of memory every 60 1683 seconds; see the memory_corruption_check_size and 1684 memory_corruption_check_period parameters in 1685 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1686 1687 When enabled with the default parameters, this option has 1688 almost no overhead, as it reserves a relatively small amount 1689 of memory and scans it infrequently. It both detects corruption 1690 and prevents it from affecting the running system. 1691 1692 It is, however, intended as a diagnostic tool; if repeatable 1693 BIOS-originated corruption always affects the same memory, 1694 you can use memmap= to prevent the kernel from using that 1695 memory. 1696 1697config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1698 bool "Set the default setting of memory_corruption_check" 1699 depends on X86_CHECK_BIOS_CORRUPTION 1700 default y 1701 help 1702 Set whether the default state of memory_corruption_check is 1703 on or off. 1704 1705config MATH_EMULATION 1706 bool 1707 depends on MODIFY_LDT_SYSCALL 1708 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1709 help 1710 Linux can emulate a math coprocessor (used for floating point 1711 operations) if you don't have one. 486DX and Pentium processors have 1712 a math coprocessor built in, 486SX and 386 do not, unless you added 1713 a 487DX or 387, respectively. (The messages during boot time can 1714 give you some hints here ["man dmesg"].) Everyone needs either a 1715 coprocessor or this emulation. 1716 1717 If you don't have a math coprocessor, you need to say Y here; if you 1718 say Y here even though you have a coprocessor, the coprocessor will 1719 be used nevertheless. (This behavior can be changed with the kernel 1720 command line option "no387", which comes handy if your coprocessor 1721 is broken. Try "man bootparam" or see the documentation of your boot 1722 loader (lilo or loadlin) about how to pass options to the kernel at 1723 boot time.) This means that it is a good idea to say Y here if you 1724 intend to use this kernel on different machines. 1725 1726 More information about the internals of the Linux math coprocessor 1727 emulation can be found in <file:arch/x86/math-emu/README>. 1728 1729 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1730 kernel, it won't hurt. 1731 1732config MTRR 1733 def_bool y 1734 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1735 help 1736 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1737 the Memory Type Range Registers (MTRRs) may be used to control 1738 processor access to memory ranges. This is most useful if you have 1739 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1740 allows bus write transfers to be combined into a larger transfer 1741 before bursting over the PCI/AGP bus. This can increase performance 1742 of image write operations 2.5 times or more. Saying Y here creates a 1743 /proc/mtrr file which may be used to manipulate your processor's 1744 MTRRs. Typically the X server should use this. 1745 1746 This code has a reasonably generic interface so that similar 1747 control registers on other processors can be easily supported 1748 as well: 1749 1750 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1751 Registers (ARRs) which provide a similar functionality to MTRRs. For 1752 these, the ARRs are used to emulate the MTRRs. 1753 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1754 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1755 write-combining. All of these processors are supported by this code 1756 and it makes sense to say Y here if you have one of them. 1757 1758 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1759 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1760 can lead to all sorts of problems, so it's good to say Y here. 1761 1762 You can safely say Y even if your machine doesn't have MTRRs, you'll 1763 just add about 9 KB to your kernel. 1764 1765 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1766 1767config MTRR_SANITIZER 1768 def_bool y 1769 prompt "MTRR cleanup support" 1770 depends on MTRR 1771 help 1772 Convert MTRR layout from continuous to discrete, so X drivers can 1773 add writeback entries. 1774 1775 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1776 The largest mtrr entry size for a continuous block can be set with 1777 mtrr_chunk_size. 1778 1779 If unsure, say Y. 1780 1781config MTRR_SANITIZER_ENABLE_DEFAULT 1782 int "MTRR cleanup enable value (0-1)" 1783 range 0 1 1784 default "0" 1785 depends on MTRR_SANITIZER 1786 help 1787 Enable mtrr cleanup default value 1788 1789config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1790 int "MTRR cleanup spare reg num (0-7)" 1791 range 0 7 1792 default "1" 1793 depends on MTRR_SANITIZER 1794 help 1795 mtrr cleanup spare entries default, it can be changed via 1796 mtrr_spare_reg_nr=N on the kernel command line. 1797 1798config X86_PAT 1799 def_bool y 1800 prompt "x86 PAT support" if EXPERT 1801 depends on MTRR 1802 help 1803 Use PAT attributes to setup page level cache control. 1804 1805 PATs are the modern equivalents of MTRRs and are much more 1806 flexible than MTRRs. 1807 1808 Say N here if you see bootup problems (boot crash, boot hang, 1809 spontaneous reboots) or a non-working video driver. 1810 1811 If unsure, say Y. 1812 1813config ARCH_USES_PG_UNCACHED 1814 def_bool y 1815 depends on X86_PAT 1816 1817config X86_UMIP 1818 def_bool y 1819 prompt "User Mode Instruction Prevention" if EXPERT 1820 help 1821 User Mode Instruction Prevention (UMIP) is a security feature in 1822 some x86 processors. If enabled, a general protection fault is 1823 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1824 executed in user mode. These instructions unnecessarily expose 1825 information about the hardware state. 1826 1827 The vast majority of applications do not use these instructions. 1828 For the very few that do, software emulation is provided in 1829 specific cases in protected and virtual-8086 modes. Emulated 1830 results are dummy. 1831 1832config CC_HAS_IBT 1833 # GCC >= 9 and binutils >= 2.29 1834 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1835 # Clang/LLVM >= 14 1836 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1837 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1838 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1839 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1840 $(as-instr,endbr64) 1841 1842config X86_CET 1843 def_bool n 1844 help 1845 CET features configured (Shadow stack or IBT) 1846 1847config X86_KERNEL_IBT 1848 prompt "Indirect Branch Tracking" 1849 def_bool y 1850 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1851 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1852 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1853 select OBJTOOL 1854 select X86_CET 1855 help 1856 Build the kernel with support for Indirect Branch Tracking, a 1857 hardware support course-grain forward-edge Control Flow Integrity 1858 protection. It enforces that all indirect calls must land on 1859 an ENDBR instruction, as such, the compiler will instrument the 1860 code with them to make this happen. 1861 1862 In addition to building the kernel with IBT, seal all functions that 1863 are not indirect call targets, avoiding them ever becoming one. 1864 1865 This requires LTO like objtool runs and will slow down the build. It 1866 does significantly reduce the number of ENDBR instructions in the 1867 kernel image. 1868 1869config X86_INTEL_MEMORY_PROTECTION_KEYS 1870 prompt "Memory Protection Keys" 1871 def_bool y 1872 # Note: only available in 64-bit mode 1873 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1874 select ARCH_USES_HIGH_VMA_FLAGS 1875 select ARCH_HAS_PKEYS 1876 help 1877 Memory Protection Keys provides a mechanism for enforcing 1878 page-based protections, but without requiring modification of the 1879 page tables when an application changes protection domains. 1880 1881 For details, see Documentation/core-api/protection-keys.rst 1882 1883 If unsure, say y. 1884 1885choice 1886 prompt "TSX enable mode" 1887 depends on CPU_SUP_INTEL 1888 default X86_INTEL_TSX_MODE_OFF 1889 help 1890 Intel's TSX (Transactional Synchronization Extensions) feature 1891 allows to optimize locking protocols through lock elision which 1892 can lead to a noticeable performance boost. 1893 1894 On the other hand it has been shown that TSX can be exploited 1895 to form side channel attacks (e.g. TAA) and chances are there 1896 will be more of those attacks discovered in the future. 1897 1898 Therefore TSX is not enabled by default (aka tsx=off). An admin 1899 might override this decision by tsx=on the command line parameter. 1900 Even with TSX enabled, the kernel will attempt to enable the best 1901 possible TAA mitigation setting depending on the microcode available 1902 for the particular machine. 1903 1904 This option allows to set the default tsx mode between tsx=on, =off 1905 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1906 details. 1907 1908 Say off if not sure, auto if TSX is in use but it should be used on safe 1909 platforms or on if TSX is in use and the security aspect of tsx is not 1910 relevant. 1911 1912config X86_INTEL_TSX_MODE_OFF 1913 bool "off" 1914 help 1915 TSX is disabled if possible - equals to tsx=off command line parameter. 1916 1917config X86_INTEL_TSX_MODE_ON 1918 bool "on" 1919 help 1920 TSX is always enabled on TSX capable HW - equals the tsx=on command 1921 line parameter. 1922 1923config X86_INTEL_TSX_MODE_AUTO 1924 bool "auto" 1925 help 1926 TSX is enabled on TSX capable HW that is believed to be safe against 1927 side channel attacks- equals the tsx=auto command line parameter. 1928endchoice 1929 1930config X86_SGX 1931 bool "Software Guard eXtensions (SGX)" 1932 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1933 depends on CRYPTO=y 1934 depends on CRYPTO_SHA256=y 1935 select MMU_NOTIFIER 1936 select NUMA_KEEP_MEMINFO if NUMA 1937 select XARRAY_MULTI 1938 help 1939 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1940 that can be used by applications to set aside private regions of code 1941 and data, referred to as enclaves. An enclave's private memory can 1942 only be accessed by code running within the enclave. Accesses from 1943 outside the enclave, including other enclaves, are disallowed by 1944 hardware. 1945 1946 If unsure, say N. 1947 1948config X86_USER_SHADOW_STACK 1949 bool "X86 userspace shadow stack" 1950 depends on AS_WRUSS 1951 depends on X86_64 1952 select ARCH_USES_HIGH_VMA_FLAGS 1953 select X86_CET 1954 help 1955 Shadow stack protection is a hardware feature that detects function 1956 return address corruption. This helps mitigate ROP attacks. 1957 Applications must be enabled to use it, and old userspace does not 1958 get protection "for free". 1959 1960 CPUs supporting shadow stacks were first released in 2020. 1961 1962 See Documentation/arch/x86/shstk.rst for more information. 1963 1964 If unsure, say N. 1965 1966config INTEL_TDX_HOST 1967 bool "Intel Trust Domain Extensions (TDX) host support" 1968 depends on CPU_SUP_INTEL 1969 depends on X86_64 1970 depends on KVM_INTEL 1971 depends on X86_X2APIC 1972 select ARCH_KEEP_MEMBLOCK 1973 depends on CONTIG_ALLOC 1974 depends on !KEXEC_CORE 1975 depends on X86_MCE 1976 help 1977 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1978 host and certain physical attacks. This option enables necessary TDX 1979 support in the host kernel to run confidential VMs. 1980 1981 If unsure, say N. 1982 1983config EFI 1984 bool "EFI runtime service support" 1985 depends on ACPI 1986 select UCS2_STRING 1987 select EFI_RUNTIME_WRAPPERS 1988 select ARCH_USE_MEMREMAP_PROT 1989 select EFI_RUNTIME_MAP if KEXEC_CORE 1990 help 1991 This enables the kernel to use EFI runtime services that are 1992 available (such as the EFI variable services). 1993 1994 This option is only useful on systems that have EFI firmware. 1995 In addition, you should use the latest ELILO loader available 1996 at <http://elilo.sourceforge.net> in order to take advantage 1997 of EFI runtime services. However, even with this option, the 1998 resultant kernel should continue to boot on existing non-EFI 1999 platforms. 2000 2001config EFI_STUB 2002 bool "EFI stub support" 2003 depends on EFI 2004 select RELOCATABLE 2005 help 2006 This kernel feature allows a bzImage to be loaded directly 2007 by EFI firmware without the use of a bootloader. 2008 2009 See Documentation/admin-guide/efi-stub.rst for more information. 2010 2011config EFI_HANDOVER_PROTOCOL 2012 bool "EFI handover protocol (DEPRECATED)" 2013 depends on EFI_STUB 2014 default y 2015 help 2016 Select this in order to include support for the deprecated EFI 2017 handover protocol, which defines alternative entry points into the 2018 EFI stub. This is a practice that has no basis in the UEFI 2019 specification, and requires a priori knowledge on the part of the 2020 bootloader about Linux/x86 specific ways of passing the command line 2021 and initrd, and where in memory those assets may be loaded. 2022 2023 If in doubt, say Y. Even though the corresponding support is not 2024 present in upstream GRUB or other bootloaders, most distros build 2025 GRUB with numerous downstream patches applied, and may rely on the 2026 handover protocol as as result. 2027 2028config EFI_MIXED 2029 bool "EFI mixed-mode support" 2030 depends on EFI_STUB && X86_64 2031 help 2032 Enabling this feature allows a 64-bit kernel to be booted 2033 on a 32-bit firmware, provided that your CPU supports 64-bit 2034 mode. 2035 2036 Note that it is not possible to boot a mixed-mode enabled 2037 kernel via the EFI boot stub - a bootloader that supports 2038 the EFI handover protocol must be used. 2039 2040 If unsure, say N. 2041 2042config EFI_FAKE_MEMMAP 2043 bool "Enable EFI fake memory map" 2044 depends on EFI 2045 help 2046 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2047 this parameter, you can add arbitrary attribute to specific memory 2048 range by updating original (firmware provided) EFI memmap. This is 2049 useful for debugging of EFI memmap related feature, e.g., Address 2050 Range Mirroring feature. 2051 2052config EFI_MAX_FAKE_MEM 2053 int "maximum allowable number of ranges in efi_fake_mem boot option" 2054 depends on EFI_FAKE_MEMMAP 2055 range 1 128 2056 default 8 2057 help 2058 Maximum allowable number of ranges in efi_fake_mem boot option. 2059 Ranges can be set up to this value using comma-separated list. 2060 The default value is 8. 2061 2062config EFI_RUNTIME_MAP 2063 bool "Export EFI runtime maps to sysfs" if EXPERT 2064 depends on EFI 2065 help 2066 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2067 That memory map is required by the 2nd kernel to set up EFI virtual 2068 mappings after kexec, but can also be used for debugging purposes. 2069 2070 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2071 2072source "kernel/Kconfig.hz" 2073 2074config ARCH_SUPPORTS_KEXEC 2075 def_bool y 2076 2077config ARCH_SUPPORTS_KEXEC_FILE 2078 def_bool X86_64 2079 2080config ARCH_SELECTS_KEXEC_FILE 2081 def_bool y 2082 depends on KEXEC_FILE 2083 select HAVE_IMA_KEXEC if IMA 2084 2085config ARCH_SUPPORTS_KEXEC_PURGATORY 2086 def_bool y 2087 2088config ARCH_SUPPORTS_KEXEC_SIG 2089 def_bool y 2090 2091config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2092 def_bool y 2093 2094config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2095 def_bool y 2096 2097config ARCH_SUPPORTS_KEXEC_JUMP 2098 def_bool y 2099 2100config ARCH_SUPPORTS_CRASH_DUMP 2101 def_bool X86_64 || (X86_32 && HIGHMEM) 2102 2103config ARCH_SUPPORTS_CRASH_HOTPLUG 2104 def_bool y 2105 2106config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2107 def_bool CRASH_RESERVE 2108 2109config PHYSICAL_START 2110 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2111 default "0x1000000" 2112 help 2113 This gives the physical address where the kernel is loaded. 2114 2115 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2116 will decompress itself to above physical address and run from there. 2117 Otherwise, bzImage will run from the address where it has been loaded 2118 by the boot loader. The only exception is if it is loaded below the 2119 above physical address, in which case it will relocate itself there. 2120 2121 In normal kdump cases one does not have to set/change this option 2122 as now bzImage can be compiled as a completely relocatable image 2123 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2124 address. This option is mainly useful for the folks who don't want 2125 to use a bzImage for capturing the crash dump and want to use a 2126 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2127 to be specifically compiled to run from a specific memory area 2128 (normally a reserved region) and this option comes handy. 2129 2130 So if you are using bzImage for capturing the crash dump, 2131 leave the value here unchanged to 0x1000000 and set 2132 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2133 for capturing the crash dump change this value to start of 2134 the reserved region. In other words, it can be set based on 2135 the "X" value as specified in the "crashkernel=YM@XM" 2136 command line boot parameter passed to the panic-ed 2137 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2138 for more details about crash dumps. 2139 2140 Usage of bzImage for capturing the crash dump is recommended as 2141 one does not have to build two kernels. Same kernel can be used 2142 as production kernel and capture kernel. Above option should have 2143 gone away after relocatable bzImage support is introduced. But it 2144 is present because there are users out there who continue to use 2145 vmlinux for dump capture. This option should go away down the 2146 line. 2147 2148 Don't change this unless you know what you are doing. 2149 2150config RELOCATABLE 2151 bool "Build a relocatable kernel" 2152 default y 2153 help 2154 This builds a kernel image that retains relocation information 2155 so it can be loaded someplace besides the default 1MB. 2156 The relocations tend to make the kernel binary about 10% larger, 2157 but are discarded at runtime. 2158 2159 One use is for the kexec on panic case where the recovery kernel 2160 must live at a different physical address than the primary 2161 kernel. 2162 2163 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2164 it has been loaded at and the compile time physical address 2165 (CONFIG_PHYSICAL_START) is used as the minimum location. 2166 2167config RANDOMIZE_BASE 2168 bool "Randomize the address of the kernel image (KASLR)" 2169 depends on RELOCATABLE 2170 default y 2171 help 2172 In support of Kernel Address Space Layout Randomization (KASLR), 2173 this randomizes the physical address at which the kernel image 2174 is decompressed and the virtual address where the kernel 2175 image is mapped, as a security feature that deters exploit 2176 attempts relying on knowledge of the location of kernel 2177 code internals. 2178 2179 On 64-bit, the kernel physical and virtual addresses are 2180 randomized separately. The physical address will be anywhere 2181 between 16MB and the top of physical memory (up to 64TB). The 2182 virtual address will be randomized from 16MB up to 1GB (9 bits 2183 of entropy). Note that this also reduces the memory space 2184 available to kernel modules from 1.5GB to 1GB. 2185 2186 On 32-bit, the kernel physical and virtual addresses are 2187 randomized together. They will be randomized from 16MB up to 2188 512MB (8 bits of entropy). 2189 2190 Entropy is generated using the RDRAND instruction if it is 2191 supported. If RDTSC is supported, its value is mixed into 2192 the entropy pool as well. If neither RDRAND nor RDTSC are 2193 supported, then entropy is read from the i8254 timer. The 2194 usable entropy is limited by the kernel being built using 2195 2GB addressing, and that PHYSICAL_ALIGN must be at a 2196 minimum of 2MB. As a result, only 10 bits of entropy are 2197 theoretically possible, but the implementations are further 2198 limited due to memory layouts. 2199 2200 If unsure, say Y. 2201 2202# Relocation on x86 needs some additional build support 2203config X86_NEED_RELOCS 2204 def_bool y 2205 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2206 2207config PHYSICAL_ALIGN 2208 hex "Alignment value to which kernel should be aligned" 2209 default "0x200000" 2210 range 0x2000 0x1000000 if X86_32 2211 range 0x200000 0x1000000 if X86_64 2212 help 2213 This value puts the alignment restrictions on physical address 2214 where kernel is loaded and run from. Kernel is compiled for an 2215 address which meets above alignment restriction. 2216 2217 If bootloader loads the kernel at a non-aligned address and 2218 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2219 address aligned to above value and run from there. 2220 2221 If bootloader loads the kernel at a non-aligned address and 2222 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2223 load address and decompress itself to the address it has been 2224 compiled for and run from there. The address for which kernel is 2225 compiled already meets above alignment restrictions. Hence the 2226 end result is that kernel runs from a physical address meeting 2227 above alignment restrictions. 2228 2229 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2230 this value must be a multiple of 0x200000. 2231 2232 Don't change this unless you know what you are doing. 2233 2234config DYNAMIC_MEMORY_LAYOUT 2235 bool 2236 help 2237 This option makes base addresses of vmalloc and vmemmap as well as 2238 __PAGE_OFFSET movable during boot. 2239 2240config RANDOMIZE_MEMORY 2241 bool "Randomize the kernel memory sections" 2242 depends on X86_64 2243 depends on RANDOMIZE_BASE 2244 select DYNAMIC_MEMORY_LAYOUT 2245 default RANDOMIZE_BASE 2246 help 2247 Randomizes the base virtual address of kernel memory sections 2248 (physical memory mapping, vmalloc & vmemmap). This security feature 2249 makes exploits relying on predictable memory locations less reliable. 2250 2251 The order of allocations remains unchanged. Entropy is generated in 2252 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2253 configuration have in average 30,000 different possible virtual 2254 addresses for each memory section. 2255 2256 If unsure, say Y. 2257 2258config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2259 hex "Physical memory mapping padding" if EXPERT 2260 depends on RANDOMIZE_MEMORY 2261 default "0xa" if MEMORY_HOTPLUG 2262 default "0x0" 2263 range 0x1 0x40 if MEMORY_HOTPLUG 2264 range 0x0 0x40 2265 help 2266 Define the padding in terabytes added to the existing physical 2267 memory size during kernel memory randomization. It is useful 2268 for memory hotplug support but reduces the entropy available for 2269 address randomization. 2270 2271 If unsure, leave at the default value. 2272 2273config ADDRESS_MASKING 2274 bool "Linear Address Masking support" 2275 depends on X86_64 2276 help 2277 Linear Address Masking (LAM) modifies the checking that is applied 2278 to 64-bit linear addresses, allowing software to use of the 2279 untranslated address bits for metadata. 2280 2281 The capability can be used for efficient address sanitizers (ASAN) 2282 implementation and for optimizations in JITs. 2283 2284config HOTPLUG_CPU 2285 def_bool y 2286 depends on SMP 2287 2288config COMPAT_VDSO 2289 def_bool n 2290 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2291 depends on COMPAT_32 2292 help 2293 Certain buggy versions of glibc will crash if they are 2294 presented with a 32-bit vDSO that is not mapped at the address 2295 indicated in its segment table. 2296 2297 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2298 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2299 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2300 the only released version with the bug, but OpenSUSE 9 2301 contains a buggy "glibc 2.3.2". 2302 2303 The symptom of the bug is that everything crashes on startup, saying: 2304 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2305 2306 Saying Y here changes the default value of the vdso32 boot 2307 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2308 This works around the glibc bug but hurts performance. 2309 2310 If unsure, say N: if you are compiling your own kernel, you 2311 are unlikely to be using a buggy version of glibc. 2312 2313choice 2314 prompt "vsyscall table for legacy applications" 2315 depends on X86_64 2316 default LEGACY_VSYSCALL_XONLY 2317 help 2318 Legacy user code that does not know how to find the vDSO expects 2319 to be able to issue three syscalls by calling fixed addresses in 2320 kernel space. Since this location is not randomized with ASLR, 2321 it can be used to assist security vulnerability exploitation. 2322 2323 This setting can be changed at boot time via the kernel command 2324 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2325 is deprecated and can only be enabled using the kernel command 2326 line. 2327 2328 On a system with recent enough glibc (2.14 or newer) and no 2329 static binaries, you can say None without a performance penalty 2330 to improve security. 2331 2332 If unsure, select "Emulate execution only". 2333 2334 config LEGACY_VSYSCALL_XONLY 2335 bool "Emulate execution only" 2336 help 2337 The kernel traps and emulates calls into the fixed vsyscall 2338 address mapping and does not allow reads. This 2339 configuration is recommended when userspace might use the 2340 legacy vsyscall area but support for legacy binary 2341 instrumentation of legacy code is not needed. It mitigates 2342 certain uses of the vsyscall area as an ASLR-bypassing 2343 buffer. 2344 2345 config LEGACY_VSYSCALL_NONE 2346 bool "None" 2347 help 2348 There will be no vsyscall mapping at all. This will 2349 eliminate any risk of ASLR bypass due to the vsyscall 2350 fixed address mapping. Attempts to use the vsyscalls 2351 will be reported to dmesg, so that either old or 2352 malicious userspace programs can be identified. 2353 2354endchoice 2355 2356config CMDLINE_BOOL 2357 bool "Built-in kernel command line" 2358 help 2359 Allow for specifying boot arguments to the kernel at 2360 build time. On some systems (e.g. embedded ones), it is 2361 necessary or convenient to provide some or all of the 2362 kernel boot arguments with the kernel itself (that is, 2363 to not rely on the boot loader to provide them.) 2364 2365 To compile command line arguments into the kernel, 2366 set this option to 'Y', then fill in the 2367 boot arguments in CONFIG_CMDLINE. 2368 2369 Systems with fully functional boot loaders (i.e. non-embedded) 2370 should leave this option set to 'N'. 2371 2372config CMDLINE 2373 string "Built-in kernel command string" 2374 depends on CMDLINE_BOOL 2375 default "" 2376 help 2377 Enter arguments here that should be compiled into the kernel 2378 image and used at boot time. If the boot loader provides a 2379 command line at boot time, it is appended to this string to 2380 form the full kernel command line, when the system boots. 2381 2382 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2383 change this behavior. 2384 2385 In most cases, the command line (whether built-in or provided 2386 by the boot loader) should specify the device for the root 2387 file system. 2388 2389config CMDLINE_OVERRIDE 2390 bool "Built-in command line overrides boot loader arguments" 2391 depends on CMDLINE_BOOL && CMDLINE != "" 2392 help 2393 Set this option to 'Y' to have the kernel ignore the boot loader 2394 command line, and use ONLY the built-in command line. 2395 2396 This is used to work around broken boot loaders. This should 2397 be set to 'N' under normal conditions. 2398 2399config MODIFY_LDT_SYSCALL 2400 bool "Enable the LDT (local descriptor table)" if EXPERT 2401 default y 2402 help 2403 Linux can allow user programs to install a per-process x86 2404 Local Descriptor Table (LDT) using the modify_ldt(2) system 2405 call. This is required to run 16-bit or segmented code such as 2406 DOSEMU or some Wine programs. It is also used by some very old 2407 threading libraries. 2408 2409 Enabling this feature adds a small amount of overhead to 2410 context switches and increases the low-level kernel attack 2411 surface. Disabling it removes the modify_ldt(2) system call. 2412 2413 Saying 'N' here may make sense for embedded or server kernels. 2414 2415config STRICT_SIGALTSTACK_SIZE 2416 bool "Enforce strict size checking for sigaltstack" 2417 depends on DYNAMIC_SIGFRAME 2418 help 2419 For historical reasons MINSIGSTKSZ is a constant which became 2420 already too small with AVX512 support. Add a mechanism to 2421 enforce strict checking of the sigaltstack size against the 2422 real size of the FPU frame. This option enables the check 2423 by default. It can also be controlled via the kernel command 2424 line option 'strict_sas_size' independent of this config 2425 switch. Enabling it might break existing applications which 2426 allocate a too small sigaltstack but 'work' because they 2427 never get a signal delivered. 2428 2429 Say 'N' unless you want to really enforce this check. 2430 2431source "kernel/livepatch/Kconfig" 2432 2433endmenu 2434 2435config CC_HAS_NAMED_AS 2436 def_bool CC_IS_GCC && GCC_VERSION >= 120100 2437 2438config USE_X86_SEG_SUPPORT 2439 def_bool y 2440 depends on CC_HAS_NAMED_AS 2441 # 2442 # -fsanitize=kernel-address (KASAN) is at the moment incompatible 2443 # with named address spaces - see GCC PR sanitizer/111736. 2444 # 2445 depends on !KASAN 2446 2447config CC_HAS_SLS 2448 def_bool $(cc-option,-mharden-sls=all) 2449 2450config CC_HAS_RETURN_THUNK 2451 def_bool $(cc-option,-mfunction-return=thunk-extern) 2452 2453config CC_HAS_ENTRY_PADDING 2454 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2455 2456config FUNCTION_PADDING_CFI 2457 int 2458 default 59 if FUNCTION_ALIGNMENT_64B 2459 default 27 if FUNCTION_ALIGNMENT_32B 2460 default 11 if FUNCTION_ALIGNMENT_16B 2461 default 3 if FUNCTION_ALIGNMENT_8B 2462 default 0 2463 2464# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2465# except Kconfig can't do arithmetic :/ 2466config FUNCTION_PADDING_BYTES 2467 int 2468 default FUNCTION_PADDING_CFI if CFI_CLANG 2469 default FUNCTION_ALIGNMENT 2470 2471config CALL_PADDING 2472 def_bool n 2473 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2474 select FUNCTION_ALIGNMENT_16B 2475 2476config FINEIBT 2477 def_bool y 2478 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE 2479 select CALL_PADDING 2480 2481config HAVE_CALL_THUNKS 2482 def_bool y 2483 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2484 2485config CALL_THUNKS 2486 def_bool n 2487 select CALL_PADDING 2488 2489config PREFIX_SYMBOLS 2490 def_bool y 2491 depends on CALL_PADDING && !CFI_CLANG 2492 2493menuconfig SPECULATION_MITIGATIONS 2494 bool "Mitigations for speculative execution vulnerabilities" 2495 default y 2496 help 2497 Say Y here to enable options which enable mitigations for 2498 speculative execution hardware vulnerabilities. 2499 2500 If you say N, all mitigations will be disabled. You really 2501 should know what you are doing to say so. 2502 2503if SPECULATION_MITIGATIONS 2504 2505config MITIGATION_PAGE_TABLE_ISOLATION 2506 bool "Remove the kernel mapping in user mode" 2507 default y 2508 depends on (X86_64 || X86_PAE) 2509 help 2510 This feature reduces the number of hardware side channels by 2511 ensuring that the majority of kernel addresses are not mapped 2512 into userspace. 2513 2514 See Documentation/arch/x86/pti.rst for more details. 2515 2516config MITIGATION_RETPOLINE 2517 bool "Avoid speculative indirect branches in kernel" 2518 select OBJTOOL if HAVE_OBJTOOL 2519 default y 2520 help 2521 Compile kernel with the retpoline compiler options to guard against 2522 kernel-to-user data leaks by avoiding speculative indirect 2523 branches. Requires a compiler with -mindirect-branch=thunk-extern 2524 support for full protection. The kernel may run slower. 2525 2526config MITIGATION_RETHUNK 2527 bool "Enable return-thunks" 2528 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2529 select OBJTOOL if HAVE_OBJTOOL 2530 default y if X86_64 2531 help 2532 Compile the kernel with the return-thunks compiler option to guard 2533 against kernel-to-user data leaks by avoiding return speculation. 2534 Requires a compiler with -mfunction-return=thunk-extern 2535 support for full protection. The kernel may run slower. 2536 2537config MITIGATION_UNRET_ENTRY 2538 bool "Enable UNRET on kernel entry" 2539 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2540 default y 2541 help 2542 Compile the kernel with support for the retbleed=unret mitigation. 2543 2544config MITIGATION_CALL_DEPTH_TRACKING 2545 bool "Mitigate RSB underflow with call depth tracking" 2546 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2547 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2548 select CALL_THUNKS 2549 default y 2550 help 2551 Compile the kernel with call depth tracking to mitigate the Intel 2552 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2553 mitigation is off by default and needs to be enabled on the 2554 kernel command line via the retbleed=stuff option. For 2555 non-affected systems the overhead of this option is marginal as 2556 the call depth tracking is using run-time generated call thunks 2557 in a compiler generated padding area and call patching. This 2558 increases text size by ~5%. For non affected systems this space 2559 is unused. On affected SKL systems this results in a significant 2560 performance gain over the IBRS mitigation. 2561 2562config CALL_THUNKS_DEBUG 2563 bool "Enable call thunks and call depth tracking debugging" 2564 depends on MITIGATION_CALL_DEPTH_TRACKING 2565 select FUNCTION_ALIGNMENT_32B 2566 default n 2567 help 2568 Enable call/ret counters for imbalance detection and build in 2569 a noisy dmesg about callthunks generation and call patching for 2570 trouble shooting. The debug prints need to be enabled on the 2571 kernel command line with 'debug-callthunks'. 2572 Only enable this when you are debugging call thunks as this 2573 creates a noticeable runtime overhead. If unsure say N. 2574 2575config MITIGATION_IBPB_ENTRY 2576 bool "Enable IBPB on kernel entry" 2577 depends on CPU_SUP_AMD && X86_64 2578 default y 2579 help 2580 Compile the kernel with support for the retbleed=ibpb mitigation. 2581 2582config MITIGATION_IBRS_ENTRY 2583 bool "Enable IBRS on kernel entry" 2584 depends on CPU_SUP_INTEL && X86_64 2585 default y 2586 help 2587 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2588 This mitigates both spectre_v2 and retbleed at great cost to 2589 performance. 2590 2591config MITIGATION_SRSO 2592 bool "Mitigate speculative RAS overflow on AMD" 2593 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2594 default y 2595 help 2596 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2597 2598config MITIGATION_SLS 2599 bool "Mitigate Straight-Line-Speculation" 2600 depends on CC_HAS_SLS && X86_64 2601 select OBJTOOL if HAVE_OBJTOOL 2602 default n 2603 help 2604 Compile the kernel with straight-line-speculation options to guard 2605 against straight line speculation. The kernel image might be slightly 2606 larger. 2607 2608config MITIGATION_GDS_FORCE 2609 bool "Force GDS Mitigation" 2610 depends on CPU_SUP_INTEL 2611 default n 2612 help 2613 Gather Data Sampling (GDS) is a hardware vulnerability which allows 2614 unprivileged speculative access to data which was previously stored in 2615 vector registers. 2616 2617 This option is equivalent to setting gather_data_sampling=force on the 2618 command line. The microcode mitigation is used if present, otherwise 2619 AVX is disabled as a mitigation. On affected systems that are missing 2620 the microcode any userspace code that unconditionally uses AVX will 2621 break with this option set. 2622 2623 Setting this option on systems not vulnerable to GDS has no effect. 2624 2625 If in doubt, say N. 2626 2627config MITIGATION_RFDS 2628 bool "RFDS Mitigation" 2629 depends on CPU_SUP_INTEL 2630 default y 2631 help 2632 Enable mitigation for Register File Data Sampling (RFDS) by default. 2633 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2634 allows unprivileged speculative access to stale data previously 2635 stored in floating point, vector and integer registers. 2636 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2637 2638endif 2639 2640config ARCH_HAS_ADD_PAGES 2641 def_bool y 2642 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2643 2644menu "Power management and ACPI options" 2645 2646config ARCH_HIBERNATION_HEADER 2647 def_bool y 2648 depends on HIBERNATION 2649 2650source "kernel/power/Kconfig" 2651 2652source "drivers/acpi/Kconfig" 2653 2654config X86_APM_BOOT 2655 def_bool y 2656 depends on APM 2657 2658menuconfig APM 2659 tristate "APM (Advanced Power Management) BIOS support" 2660 depends on X86_32 && PM_SLEEP 2661 help 2662 APM is a BIOS specification for saving power using several different 2663 techniques. This is mostly useful for battery powered laptops with 2664 APM compliant BIOSes. If you say Y here, the system time will be 2665 reset after a RESUME operation, the /proc/apm device will provide 2666 battery status information, and user-space programs will receive 2667 notification of APM "events" (e.g. battery status change). 2668 2669 If you select "Y" here, you can disable actual use of the APM 2670 BIOS by passing the "apm=off" option to the kernel at boot time. 2671 2672 Note that the APM support is almost completely disabled for 2673 machines with more than one CPU. 2674 2675 In order to use APM, you will need supporting software. For location 2676 and more information, read <file:Documentation/power/apm-acpi.rst> 2677 and the Battery Powered Linux mini-HOWTO, available from 2678 <http://www.tldp.org/docs.html#howto>. 2679 2680 This driver does not spin down disk drives (see the hdparm(8) 2681 manpage ("man 8 hdparm") for that), and it doesn't turn off 2682 VESA-compliant "green" monitors. 2683 2684 This driver does not support the TI 4000M TravelMate and the ACER 2685 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2686 desktop machines also don't have compliant BIOSes, and this driver 2687 may cause those machines to panic during the boot phase. 2688 2689 Generally, if you don't have a battery in your machine, there isn't 2690 much point in using this driver and you should say N. If you get 2691 random kernel OOPSes or reboots that don't seem to be related to 2692 anything, try disabling/enabling this option (or disabling/enabling 2693 APM in your BIOS). 2694 2695 Some other things you should try when experiencing seemingly random, 2696 "weird" problems: 2697 2698 1) make sure that you have enough swap space and that it is 2699 enabled. 2700 2) pass the "idle=poll" option to the kernel 2701 3) switch on floating point emulation in the kernel and pass 2702 the "no387" option to the kernel 2703 4) pass the "floppy=nodma" option to the kernel 2704 5) pass the "mem=4M" option to the kernel (thereby disabling 2705 all but the first 4 MB of RAM) 2706 6) make sure that the CPU is not over clocked. 2707 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2708 8) disable the cache from your BIOS settings 2709 9) install a fan for the video card or exchange video RAM 2710 10) install a better fan for the CPU 2711 11) exchange RAM chips 2712 12) exchange the motherboard. 2713 2714 To compile this driver as a module, choose M here: the 2715 module will be called apm. 2716 2717if APM 2718 2719config APM_IGNORE_USER_SUSPEND 2720 bool "Ignore USER SUSPEND" 2721 help 2722 This option will ignore USER SUSPEND requests. On machines with a 2723 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2724 series notebooks, it is necessary to say Y because of a BIOS bug. 2725 2726config APM_DO_ENABLE 2727 bool "Enable PM at boot time" 2728 help 2729 Enable APM features at boot time. From page 36 of the APM BIOS 2730 specification: "When disabled, the APM BIOS does not automatically 2731 power manage devices, enter the Standby State, enter the Suspend 2732 State, or take power saving steps in response to CPU Idle calls." 2733 This driver will make CPU Idle calls when Linux is idle (unless this 2734 feature is turned off -- see "Do CPU IDLE calls", below). This 2735 should always save battery power, but more complicated APM features 2736 will be dependent on your BIOS implementation. You may need to turn 2737 this option off if your computer hangs at boot time when using APM 2738 support, or if it beeps continuously instead of suspending. Turn 2739 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2740 T400CDT. This is off by default since most machines do fine without 2741 this feature. 2742 2743config APM_CPU_IDLE 2744 depends on CPU_IDLE 2745 bool "Make CPU Idle calls when idle" 2746 help 2747 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2748 On some machines, this can activate improved power savings, such as 2749 a slowed CPU clock rate, when the machine is idle. These idle calls 2750 are made after the idle loop has run for some length of time (e.g., 2751 333 mS). On some machines, this will cause a hang at boot time or 2752 whenever the CPU becomes idle. (On machines with more than one CPU, 2753 this option does nothing.) 2754 2755config APM_DISPLAY_BLANK 2756 bool "Enable console blanking using APM" 2757 help 2758 Enable console blanking using the APM. Some laptops can use this to 2759 turn off the LCD backlight when the screen blanker of the Linux 2760 virtual console blanks the screen. Note that this is only used by 2761 the virtual console screen blanker, and won't turn off the backlight 2762 when using the X Window system. This also doesn't have anything to 2763 do with your VESA-compliant power-saving monitor. Further, this 2764 option doesn't work for all laptops -- it might not turn off your 2765 backlight at all, or it might print a lot of errors to the console, 2766 especially if you are using gpm. 2767 2768config APM_ALLOW_INTS 2769 bool "Allow interrupts during APM BIOS calls" 2770 help 2771 Normally we disable external interrupts while we are making calls to 2772 the APM BIOS as a measure to lessen the effects of a badly behaving 2773 BIOS implementation. The BIOS should reenable interrupts if it 2774 needs to. Unfortunately, some BIOSes do not -- especially those in 2775 many of the newer IBM Thinkpads. If you experience hangs when you 2776 suspend, try setting this to Y. Otherwise, say N. 2777 2778endif # APM 2779 2780source "drivers/cpufreq/Kconfig" 2781 2782source "drivers/cpuidle/Kconfig" 2783 2784source "drivers/idle/Kconfig" 2785 2786endmenu 2787 2788menu "Bus options (PCI etc.)" 2789 2790choice 2791 prompt "PCI access mode" 2792 depends on X86_32 && PCI 2793 default PCI_GOANY 2794 help 2795 On PCI systems, the BIOS can be used to detect the PCI devices and 2796 determine their configuration. However, some old PCI motherboards 2797 have BIOS bugs and may crash if this is done. Also, some embedded 2798 PCI-based systems don't have any BIOS at all. Linux can also try to 2799 detect the PCI hardware directly without using the BIOS. 2800 2801 With this option, you can specify how Linux should detect the 2802 PCI devices. If you choose "BIOS", the BIOS will be used, 2803 if you choose "Direct", the BIOS won't be used, and if you 2804 choose "MMConfig", then PCI Express MMCONFIG will be used. 2805 If you choose "Any", the kernel will try MMCONFIG, then the 2806 direct access method and falls back to the BIOS if that doesn't 2807 work. If unsure, go with the default, which is "Any". 2808 2809config PCI_GOBIOS 2810 bool "BIOS" 2811 2812config PCI_GOMMCONFIG 2813 bool "MMConfig" 2814 2815config PCI_GODIRECT 2816 bool "Direct" 2817 2818config PCI_GOOLPC 2819 bool "OLPC XO-1" 2820 depends on OLPC 2821 2822config PCI_GOANY 2823 bool "Any" 2824 2825endchoice 2826 2827config PCI_BIOS 2828 def_bool y 2829 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2830 2831# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2832config PCI_DIRECT 2833 def_bool y 2834 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2835 2836config PCI_MMCONFIG 2837 bool "Support mmconfig PCI config space access" if X86_64 2838 default y 2839 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2840 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2841 2842config PCI_OLPC 2843 def_bool y 2844 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2845 2846config PCI_XEN 2847 def_bool y 2848 depends on PCI && XEN 2849 2850config MMCONF_FAM10H 2851 def_bool y 2852 depends on X86_64 && PCI_MMCONFIG && ACPI 2853 2854config PCI_CNB20LE_QUIRK 2855 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2856 depends on PCI 2857 help 2858 Read the PCI windows out of the CNB20LE host bridge. This allows 2859 PCI hotplug to work on systems with the CNB20LE chipset which do 2860 not have ACPI. 2861 2862 There's no public spec for this chipset, and this functionality 2863 is known to be incomplete. 2864 2865 You should say N unless you know you need this. 2866 2867config ISA_BUS 2868 bool "ISA bus support on modern systems" if EXPERT 2869 help 2870 Expose ISA bus device drivers and options available for selection and 2871 configuration. Enable this option if your target machine has an ISA 2872 bus. ISA is an older system, displaced by PCI and newer bus 2873 architectures -- if your target machine is modern, it probably does 2874 not have an ISA bus. 2875 2876 If unsure, say N. 2877 2878# x86_64 have no ISA slots, but can have ISA-style DMA. 2879config ISA_DMA_API 2880 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2881 default y 2882 help 2883 Enables ISA-style DMA support for devices requiring such controllers. 2884 If unsure, say Y. 2885 2886if X86_32 2887 2888config ISA 2889 bool "ISA support" 2890 help 2891 Find out whether you have ISA slots on your motherboard. ISA is the 2892 name of a bus system, i.e. the way the CPU talks to the other stuff 2893 inside your box. Other bus systems are PCI, EISA, MicroChannel 2894 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2895 newer boards don't support it. If you have ISA, say Y, otherwise N. 2896 2897config SCx200 2898 tristate "NatSemi SCx200 support" 2899 help 2900 This provides basic support for National Semiconductor's 2901 (now AMD's) Geode processors. The driver probes for the 2902 PCI-IDs of several on-chip devices, so its a good dependency 2903 for other scx200_* drivers. 2904 2905 If compiled as a module, the driver is named scx200. 2906 2907config SCx200HR_TIMER 2908 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2909 depends on SCx200 2910 default y 2911 help 2912 This driver provides a clocksource built upon the on-chip 2913 27MHz high-resolution timer. Its also a workaround for 2914 NSC Geode SC-1100's buggy TSC, which loses time when the 2915 processor goes idle (as is done by the scheduler). The 2916 other workaround is idle=poll boot option. 2917 2918config OLPC 2919 bool "One Laptop Per Child support" 2920 depends on !X86_PAE 2921 select GPIOLIB 2922 select OF 2923 select OF_PROMTREE 2924 select IRQ_DOMAIN 2925 select OLPC_EC 2926 help 2927 Add support for detecting the unique features of the OLPC 2928 XO hardware. 2929 2930config OLPC_XO1_PM 2931 bool "OLPC XO-1 Power Management" 2932 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2933 help 2934 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2935 2936config OLPC_XO1_RTC 2937 bool "OLPC XO-1 Real Time Clock" 2938 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2939 help 2940 Add support for the XO-1 real time clock, which can be used as a 2941 programmable wakeup source. 2942 2943config OLPC_XO1_SCI 2944 bool "OLPC XO-1 SCI extras" 2945 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2946 depends on INPUT=y 2947 select POWER_SUPPLY 2948 help 2949 Add support for SCI-based features of the OLPC XO-1 laptop: 2950 - EC-driven system wakeups 2951 - Power button 2952 - Ebook switch 2953 - Lid switch 2954 - AC adapter status updates 2955 - Battery status updates 2956 2957config OLPC_XO15_SCI 2958 bool "OLPC XO-1.5 SCI extras" 2959 depends on OLPC && ACPI 2960 select POWER_SUPPLY 2961 help 2962 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2963 - EC-driven system wakeups 2964 - AC adapter status updates 2965 - Battery status updates 2966 2967config ALIX 2968 bool "PCEngines ALIX System Support (LED setup)" 2969 select GPIOLIB 2970 help 2971 This option enables system support for the PCEngines ALIX. 2972 At present this just sets up LEDs for GPIO control on 2973 ALIX2/3/6 boards. However, other system specific setup should 2974 get added here. 2975 2976 Note: You must still enable the drivers for GPIO and LED support 2977 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2978 2979 Note: You have to set alix.force=1 for boards with Award BIOS. 2980 2981config NET5501 2982 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2983 select GPIOLIB 2984 help 2985 This option enables system support for the Soekris Engineering net5501. 2986 2987config GEOS 2988 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2989 select GPIOLIB 2990 depends on DMI 2991 help 2992 This option enables system support for the Traverse Technologies GEOS. 2993 2994config TS5500 2995 bool "Technologic Systems TS-5500 platform support" 2996 depends on MELAN 2997 select CHECK_SIGNATURE 2998 select NEW_LEDS 2999 select LEDS_CLASS 3000 help 3001 This option enables system support for the Technologic Systems TS-5500. 3002 3003endif # X86_32 3004 3005config AMD_NB 3006 def_bool y 3007 depends on CPU_SUP_AMD && PCI 3008 3009endmenu 3010 3011menu "Binary Emulations" 3012 3013config IA32_EMULATION 3014 bool "IA32 Emulation" 3015 depends on X86_64 3016 select ARCH_WANT_OLD_COMPAT_IPC 3017 select BINFMT_ELF 3018 select COMPAT_OLD_SIGACTION 3019 help 3020 Include code to run legacy 32-bit programs under a 3021 64-bit kernel. You should likely turn this on, unless you're 3022 100% sure that you don't have any 32-bit programs left. 3023 3024config IA32_EMULATION_DEFAULT_DISABLED 3025 bool "IA32 emulation disabled by default" 3026 default n 3027 depends on IA32_EMULATION 3028 help 3029 Make IA32 emulation disabled by default. This prevents loading 32-bit 3030 processes and access to 32-bit syscalls. If unsure, leave it to its 3031 default value. 3032 3033config X86_X32_ABI 3034 bool "x32 ABI for 64-bit mode" 3035 depends on X86_64 3036 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3037 # compressed debug sections to x86_x32 properly: 3038 # https://github.com/ClangBuiltLinux/linux/issues/514 3039 # https://github.com/ClangBuiltLinux/linux/issues/1141 3040 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3041 help 3042 Include code to run binaries for the x32 native 32-bit ABI 3043 for 64-bit processors. An x32 process gets access to the 3044 full 64-bit register file and wide data path while leaving 3045 pointers at 32 bits for smaller memory footprint. 3046 3047config COMPAT_32 3048 def_bool y 3049 depends on IA32_EMULATION || X86_32 3050 select HAVE_UID16 3051 select OLD_SIGSUSPEND3 3052 3053config COMPAT 3054 def_bool y 3055 depends on IA32_EMULATION || X86_X32_ABI 3056 3057config COMPAT_FOR_U64_ALIGNMENT 3058 def_bool y 3059 depends on COMPAT 3060 3061endmenu 3062 3063config HAVE_ATOMIC_IOMAP 3064 def_bool y 3065 depends on X86_32 3066 3067source "arch/x86/kvm/Kconfig" 3068 3069source "arch/x86/Kconfig.assembler" 3070