1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select HAVE_ARCH_SOFT_DIRTY 32 select MODULES_USE_ELF_RELA 33 select NEED_DMA_MAP_STATE 34 select SWIOTLB 35 select ARCH_HAS_ELFCORE_COMPAT 36 select ZONE_DMA32 37 select EXECMEM if DYNAMIC_FTRACE 38 39config FORCE_DYNAMIC_FTRACE 40 def_bool y 41 depends on X86_32 42 depends on FUNCTION_TRACER 43 select DYNAMIC_FTRACE 44 help 45 We keep the static function tracing (!DYNAMIC_FTRACE) around 46 in order to test the non static function tracing in the 47 generic code, as other architectures still use it. But we 48 only need to keep it around for x86_64. No need to keep it 49 for x86_32. For x86_32, force DYNAMIC_FTRACE. 50# 51# Arch settings 52# 53# ( Note that options that are marked 'if X86_64' could in principle be 54# ported to 32-bit as well. ) 55# 56config X86 57 def_bool y 58 # 59 # Note: keep this list sorted alphabetically 60 # 61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 63 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 64 select ARCH_32BIT_OFF_T if X86_32 65 select ARCH_CLOCKSOURCE_INIT 66 select ARCH_CONFIGURES_CPU_MITIGATIONS 67 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 68 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 69 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 70 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 71 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 72 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 73 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 74 select ARCH_HAS_CACHE_LINE_SIZE 75 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 76 select ARCH_HAS_CPU_FINALIZE_INIT 77 select ARCH_HAS_CPU_PASID if IOMMU_SVA 78 select ARCH_HAS_CURRENT_STACK_POINTER 79 select ARCH_HAS_DEBUG_VIRTUAL 80 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 81 select ARCH_HAS_DEVMEM_IS_ALLOWED 82 select ARCH_HAS_EARLY_DEBUG if KGDB 83 select ARCH_HAS_ELF_RANDOMIZE 84 select ARCH_HAS_FAST_MULTIPLIER 85 select ARCH_HAS_FORTIFY_SOURCE 86 select ARCH_HAS_GCOV_PROFILE_ALL 87 select ARCH_HAS_KCOV if X86_64 88 select ARCH_HAS_KERNEL_FPU_SUPPORT 89 select ARCH_HAS_MEM_ENCRYPT 90 select ARCH_HAS_MEMBARRIER_SYNC_CORE 91 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 92 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 93 select ARCH_HAS_PMEM_API if X86_64 94 select ARCH_HAS_PTE_DEVMAP if X86_64 95 select ARCH_HAS_PTE_SPECIAL 96 select ARCH_HAS_HW_PTE_YOUNG 97 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 98 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 99 select ARCH_HAS_COPY_MC if X86_64 100 select ARCH_HAS_SET_MEMORY 101 select ARCH_HAS_SET_DIRECT_MAP 102 select ARCH_HAS_STRICT_KERNEL_RWX 103 select ARCH_HAS_STRICT_MODULE_RWX 104 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 105 select ARCH_HAS_SYSCALL_WRAPPER 106 select ARCH_HAS_UBSAN 107 select ARCH_HAS_DEBUG_WX 108 select ARCH_HAS_ZONE_DMA_SET if EXPERT 109 select ARCH_HAVE_NMI_SAFE_CMPXCHG 110 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 111 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 112 select ARCH_MIGHT_HAVE_PC_PARPORT 113 select ARCH_MIGHT_HAVE_PC_SERIO 114 select ARCH_STACKWALK 115 select ARCH_SUPPORTS_ACPI 116 select ARCH_SUPPORTS_ATOMIC_RMW 117 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 118 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 119 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 120 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 121 select ARCH_SUPPORTS_CFI_CLANG if X86_64 122 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 123 select ARCH_SUPPORTS_LTO_CLANG 124 select ARCH_SUPPORTS_LTO_CLANG_THIN 125 select ARCH_USE_BUILTIN_BSWAP 126 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64 127 select ARCH_USE_MEMTEST 128 select ARCH_USE_QUEUED_RWLOCKS 129 select ARCH_USE_QUEUED_SPINLOCKS 130 select ARCH_USE_SYM_ANNOTATIONS 131 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 132 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 133 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 134 select ARCH_WANTS_NO_INSTR 135 select ARCH_WANT_GENERAL_HUGETLB 136 select ARCH_WANT_HUGE_PMD_SHARE 137 select ARCH_WANT_LD_ORPHAN_WARN 138 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 139 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 140 select ARCH_WANTS_THP_SWAP if X86_64 141 select ARCH_HAS_PARANOID_L1D_FLUSH 142 select BUILDTIME_TABLE_SORT 143 select CLKEVT_I8253 144 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 145 select CLOCKSOURCE_WATCHDOG 146 # Word-size accesses may read uninitialized data past the trailing \0 147 # in strings and cause false KMSAN reports. 148 select DCACHE_WORD_ACCESS if !KMSAN 149 select DYNAMIC_SIGFRAME 150 select EDAC_ATOMIC_SCRUB 151 select EDAC_SUPPORT 152 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 153 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 154 select GENERIC_CLOCKEVENTS_MIN_ADJUST 155 select GENERIC_CMOS_UPDATE 156 select GENERIC_CPU_AUTOPROBE 157 select GENERIC_CPU_DEVICES 158 select GENERIC_CPU_VULNERABILITIES 159 select GENERIC_EARLY_IOREMAP 160 select GENERIC_ENTRY 161 select GENERIC_IOMAP 162 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 163 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 164 select GENERIC_IRQ_MIGRATION if SMP 165 select GENERIC_IRQ_PROBE 166 select GENERIC_IRQ_RESERVATION_MODE 167 select GENERIC_IRQ_SHOW 168 select GENERIC_PENDING_IRQ if SMP 169 select GENERIC_PTDUMP 170 select GENERIC_SMP_IDLE_THREAD 171 select GENERIC_TIME_VSYSCALL 172 select GENERIC_GETTIMEOFDAY 173 select GENERIC_VDSO_TIME_NS 174 select GENERIC_VDSO_OVERFLOW_PROTECT 175 select GUP_GET_PXX_LOW_HIGH if X86_PAE 176 select HARDIRQS_SW_RESEND 177 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 178 select HAS_IOPORT 179 select HAVE_ACPI_APEI if ACPI 180 select HAVE_ACPI_APEI_NMI if ACPI 181 select HAVE_ALIGNED_STRUCT_PAGE 182 select HAVE_ARCH_AUDITSYSCALL 183 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 184 select HAVE_ARCH_HUGE_VMALLOC if X86_64 185 select HAVE_ARCH_JUMP_LABEL 186 select HAVE_ARCH_JUMP_LABEL_RELATIVE 187 select HAVE_ARCH_KASAN if X86_64 188 select HAVE_ARCH_KASAN_VMALLOC if X86_64 189 select HAVE_ARCH_KFENCE 190 select HAVE_ARCH_KMSAN if X86_64 191 select HAVE_ARCH_KGDB 192 select HAVE_ARCH_MMAP_RND_BITS if MMU 193 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 194 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 195 select HAVE_ARCH_PREL32_RELOCATIONS 196 select HAVE_ARCH_SECCOMP_FILTER 197 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 198 select HAVE_ARCH_STACKLEAK 199 select HAVE_ARCH_TRACEHOOK 200 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 201 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 202 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 203 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 204 select HAVE_ARCH_VMAP_STACK if X86_64 205 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 206 select HAVE_ARCH_WITHIN_STACK_FRAMES 207 select HAVE_ASM_MODVERSIONS 208 select HAVE_CMPXCHG_DOUBLE 209 select HAVE_CMPXCHG_LOCAL 210 select HAVE_CONTEXT_TRACKING_USER if X86_64 211 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 212 select HAVE_C_RECORDMCOUNT 213 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 214 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 215 select HAVE_BUILDTIME_MCOUNT_SORT 216 select HAVE_DEBUG_KMEMLEAK 217 select HAVE_DMA_CONTIGUOUS 218 select HAVE_DYNAMIC_FTRACE 219 select HAVE_DYNAMIC_FTRACE_WITH_REGS 220 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 221 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 222 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 223 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 224 select HAVE_EBPF_JIT 225 select HAVE_EFFICIENT_UNALIGNED_ACCESS 226 select HAVE_EISA 227 select HAVE_EXIT_THREAD 228 select HAVE_GUP_FAST 229 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 230 select HAVE_FTRACE_MCOUNT_RECORD 231 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 232 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 233 select HAVE_FUNCTION_TRACER 234 select HAVE_GCC_PLUGINS 235 select HAVE_HW_BREAKPOINT 236 select HAVE_IOREMAP_PROT 237 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 238 select HAVE_IRQ_TIME_ACCOUNTING 239 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 240 select HAVE_KERNEL_BZIP2 241 select HAVE_KERNEL_GZIP 242 select HAVE_KERNEL_LZ4 243 select HAVE_KERNEL_LZMA 244 select HAVE_KERNEL_LZO 245 select HAVE_KERNEL_XZ 246 select HAVE_KERNEL_ZSTD 247 select HAVE_KPROBES 248 select HAVE_KPROBES_ON_FTRACE 249 select HAVE_FUNCTION_ERROR_INJECTION 250 select HAVE_KRETPROBES 251 select HAVE_RETHOOK 252 select HAVE_LIVEPATCH if X86_64 253 select HAVE_MIXED_BREAKPOINTS_REGS 254 select HAVE_MOD_ARCH_SPECIFIC 255 select HAVE_MOVE_PMD 256 select HAVE_MOVE_PUD 257 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 258 select HAVE_NMI 259 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 260 select HAVE_OBJTOOL if X86_64 261 select HAVE_OPTPROBES 262 select HAVE_PAGE_SIZE_4KB 263 select HAVE_PCSPKR_PLATFORM 264 select HAVE_PERF_EVENTS 265 select HAVE_PERF_EVENTS_NMI 266 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 267 select HAVE_PCI 268 select HAVE_PERF_REGS 269 select HAVE_PERF_USER_STACK_DUMP 270 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 271 select MMU_GATHER_MERGE_VMAS 272 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 273 select HAVE_REGS_AND_STACK_ACCESS_API 274 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 275 select HAVE_FUNCTION_ARG_ACCESS_API 276 select HAVE_SETUP_PER_CPU_AREA 277 select HAVE_SOFTIRQ_ON_OWN_STACK 278 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 279 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 280 select HAVE_STATIC_CALL 281 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 282 select HAVE_PREEMPT_DYNAMIC_CALL 283 select HAVE_RSEQ 284 select HAVE_RUST if X86_64 285 select HAVE_SYSCALL_TRACEPOINTS 286 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 287 select HAVE_UNSTABLE_SCHED_CLOCK 288 select HAVE_USER_RETURN_NOTIFIER 289 select HAVE_GENERIC_VDSO 290 select VDSO_GETRANDOM if X86_64 291 select HOTPLUG_PARALLEL if SMP && X86_64 292 select HOTPLUG_SMT if SMP 293 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 294 select IRQ_FORCED_THREADING 295 select LOCK_MM_AND_FIND_VMA 296 select NEED_PER_CPU_EMBED_FIRST_CHUNK 297 select NEED_PER_CPU_PAGE_FIRST_CHUNK 298 select NEED_SG_DMA_LENGTH 299 select NUMA_MEMBLKS if NUMA 300 select PCI_DOMAINS if PCI 301 select PCI_LOCKLESS_CONFIG if PCI 302 select PERF_EVENTS 303 select RTC_LIB 304 select RTC_MC146818_LIB 305 select SPARSE_IRQ 306 select SYSCTL_EXCEPTION_TRACE 307 select THREAD_INFO_IN_TASK 308 select TRACE_IRQFLAGS_SUPPORT 309 select TRACE_IRQFLAGS_NMI_SUPPORT 310 select USER_STACKTRACE_SUPPORT 311 select HAVE_ARCH_KCSAN if X86_64 312 select PROC_PID_ARCH_STATUS if PROC_FS 313 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 314 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 315 select FUNCTION_ALIGNMENT_4B 316 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 317 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 318 319config INSTRUCTION_DECODER 320 def_bool y 321 depends on KPROBES || PERF_EVENTS || UPROBES 322 323config OUTPUT_FORMAT 324 string 325 default "elf32-i386" if X86_32 326 default "elf64-x86-64" if X86_64 327 328config LOCKDEP_SUPPORT 329 def_bool y 330 331config STACKTRACE_SUPPORT 332 def_bool y 333 334config MMU 335 def_bool y 336 337config ARCH_MMAP_RND_BITS_MIN 338 default 28 if 64BIT 339 default 8 340 341config ARCH_MMAP_RND_BITS_MAX 342 default 32 if 64BIT 343 default 16 344 345config ARCH_MMAP_RND_COMPAT_BITS_MIN 346 default 8 347 348config ARCH_MMAP_RND_COMPAT_BITS_MAX 349 default 16 350 351config SBUS 352 bool 353 354config GENERIC_ISA_DMA 355 def_bool y 356 depends on ISA_DMA_API 357 358config GENERIC_CSUM 359 bool 360 default y if KMSAN || KASAN 361 362config GENERIC_BUG 363 def_bool y 364 depends on BUG 365 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 366 367config GENERIC_BUG_RELATIVE_POINTERS 368 bool 369 370config ARCH_MAY_HAVE_PC_FDC 371 def_bool y 372 depends on ISA_DMA_API 373 374config GENERIC_CALIBRATE_DELAY 375 def_bool y 376 377config ARCH_HAS_CPU_RELAX 378 def_bool y 379 380config ARCH_HIBERNATION_POSSIBLE 381 def_bool y 382 383config ARCH_SUSPEND_POSSIBLE 384 def_bool y 385 386config AUDIT_ARCH 387 def_bool y if X86_64 388 389config KASAN_SHADOW_OFFSET 390 hex 391 depends on KASAN 392 default 0xdffffc0000000000 393 394config HAVE_INTEL_TXT 395 def_bool y 396 depends on INTEL_IOMMU && ACPI 397 398config X86_64_SMP 399 def_bool y 400 depends on X86_64 && SMP 401 402config ARCH_SUPPORTS_UPROBES 403 def_bool y 404 405config FIX_EARLYCON_MEM 406 def_bool y 407 408config DYNAMIC_PHYSICAL_MASK 409 bool 410 411config PGTABLE_LEVELS 412 int 413 default 5 if X86_5LEVEL 414 default 4 if X86_64 415 default 3 if X86_PAE 416 default 2 417 418config CC_HAS_SANE_STACKPROTECTOR 419 bool 420 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 421 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 422 help 423 We have to make sure stack protector is unconditionally disabled if 424 the compiler produces broken code or if it does not let us control 425 the segment on 32-bit kernels. 426 427menu "Processor type and features" 428 429config SMP 430 bool "Symmetric multi-processing support" 431 help 432 This enables support for systems with more than one CPU. If you have 433 a system with only one CPU, say N. If you have a system with more 434 than one CPU, say Y. 435 436 If you say N here, the kernel will run on uni- and multiprocessor 437 machines, but will use only one CPU of a multiprocessor machine. If 438 you say Y here, the kernel will run on many, but not all, 439 uniprocessor machines. On a uniprocessor machine, the kernel 440 will run faster if you say N here. 441 442 Note that if you say Y here and choose architecture "586" or 443 "Pentium" under "Processor family", the kernel will not work on 486 444 architectures. Similarly, multiprocessor kernels for the "PPro" 445 architecture may not work on all Pentium based boards. 446 447 People using multiprocessor machines who say Y here should also say 448 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 449 Management" code will be disabled if you say Y here. 450 451 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 452 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 453 <http://www.tldp.org/docs.html#howto>. 454 455 If you don't know what to do here, say N. 456 457config X86_X2APIC 458 bool "Support x2apic" 459 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 460 help 461 This enables x2apic support on CPUs that have this feature. 462 463 This allows 32-bit apic IDs (so it can support very large systems), 464 and accesses the local apic via MSRs not via mmio. 465 466 Some Intel systems circa 2022 and later are locked into x2APIC mode 467 and can not fall back to the legacy APIC modes if SGX or TDX are 468 enabled in the BIOS. They will boot with very reduced functionality 469 without enabling this option. 470 471 If you don't know what to do here, say N. 472 473config X86_POSTED_MSI 474 bool "Enable MSI and MSI-x delivery by posted interrupts" 475 depends on X86_64 && IRQ_REMAP 476 help 477 This enables MSIs that are under interrupt remapping to be delivered as 478 posted interrupts to the host kernel. Interrupt throughput can 479 potentially be improved by coalescing CPU notifications during high 480 frequency bursts. 481 482 If you don't know what to do here, say N. 483 484config X86_MPPARSE 485 bool "Enable MPS table" if ACPI 486 default y 487 depends on X86_LOCAL_APIC 488 help 489 For old smp systems that do not have proper acpi support. Newer systems 490 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 491 492config X86_CPU_RESCTRL 493 bool "x86 CPU resource control support" 494 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 495 select KERNFS 496 select PROC_CPU_RESCTRL if PROC_FS 497 help 498 Enable x86 CPU resource control support. 499 500 Provide support for the allocation and monitoring of system resources 501 usage by the CPU. 502 503 Intel calls this Intel Resource Director Technology 504 (Intel(R) RDT). More information about RDT can be found in the 505 Intel x86 Architecture Software Developer Manual. 506 507 AMD calls this AMD Platform Quality of Service (AMD QoS). 508 More information about AMD QoS can be found in the AMD64 Technology 509 Platform Quality of Service Extensions manual. 510 511 Say N if unsure. 512 513config X86_FRED 514 bool "Flexible Return and Event Delivery" 515 depends on X86_64 516 help 517 When enabled, try to use Flexible Return and Event Delivery 518 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 519 ring transitions and exception/interrupt handling if the 520 system supports it. 521 522config X86_BIGSMP 523 bool "Support for big SMP systems with more than 8 CPUs" 524 depends on SMP && X86_32 525 help 526 This option is needed for the systems that have more than 8 CPUs. 527 528config X86_EXTENDED_PLATFORM 529 bool "Support for extended (non-PC) x86 platforms" 530 default y 531 help 532 If you disable this option then the kernel will only support 533 standard PC platforms. (which covers the vast majority of 534 systems out there.) 535 536 If you enable this option then you'll be able to select support 537 for the following non-PC x86 platforms, depending on the value of 538 CONFIG_64BIT. 539 540 32-bit platforms (CONFIG_64BIT=n): 541 Goldfish (Android emulator) 542 AMD Elan 543 RDC R-321x SoC 544 SGI 320/540 (Visual Workstation) 545 STA2X11-based (e.g. Northville) 546 Moorestown MID devices 547 548 64-bit platforms (CONFIG_64BIT=y): 549 Numascale NumaChip 550 ScaleMP vSMP 551 SGI Ultraviolet 552 553 If you have one of these systems, or if you want to build a 554 generic distribution kernel, say Y here - otherwise say N. 555 556# This is an alphabetically sorted list of 64 bit extended platforms 557# Please maintain the alphabetic order if and when there are additions 558config X86_NUMACHIP 559 bool "Numascale NumaChip" 560 depends on X86_64 561 depends on X86_EXTENDED_PLATFORM 562 depends on NUMA 563 depends on SMP 564 depends on X86_X2APIC 565 depends on PCI_MMCONFIG 566 help 567 Adds support for Numascale NumaChip large-SMP systems. Needed to 568 enable more than ~168 cores. 569 If you don't have one of these, you should say N here. 570 571config X86_VSMP 572 bool "ScaleMP vSMP" 573 select HYPERVISOR_GUEST 574 select PARAVIRT 575 depends on X86_64 && PCI 576 depends on X86_EXTENDED_PLATFORM 577 depends on SMP 578 help 579 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 580 supposed to run on these EM64T-based machines. Only choose this option 581 if you have one of these machines. 582 583config X86_UV 584 bool "SGI Ultraviolet" 585 depends on X86_64 586 depends on X86_EXTENDED_PLATFORM 587 depends on NUMA 588 depends on EFI 589 depends on KEXEC_CORE 590 depends on X86_X2APIC 591 depends on PCI 592 help 593 This option is needed in order to support SGI Ultraviolet systems. 594 If you don't have one of these, you should say N here. 595 596# Following is an alphabetically sorted list of 32 bit extended platforms 597# Please maintain the alphabetic order if and when there are additions 598 599config X86_GOLDFISH 600 bool "Goldfish (Virtual Platform)" 601 depends on X86_EXTENDED_PLATFORM 602 help 603 Enable support for the Goldfish virtual platform used primarily 604 for Android development. Unless you are building for the Android 605 Goldfish emulator say N here. 606 607config X86_INTEL_CE 608 bool "CE4100 TV platform" 609 depends on PCI 610 depends on PCI_GODIRECT 611 depends on X86_IO_APIC 612 depends on X86_32 613 depends on X86_EXTENDED_PLATFORM 614 select X86_REBOOTFIXUPS 615 select OF 616 select OF_EARLY_FLATTREE 617 help 618 Select for the Intel CE media processor (CE4100) SOC. 619 This option compiles in support for the CE4100 SOC for settop 620 boxes and media devices. 621 622config X86_INTEL_MID 623 bool "Intel MID platform support" 624 depends on X86_EXTENDED_PLATFORM 625 depends on X86_PLATFORM_DEVICES 626 depends on PCI 627 depends on X86_64 || (PCI_GOANY && X86_32) 628 depends on X86_IO_APIC 629 select I2C 630 select DW_APB_TIMER 631 select INTEL_SCU_PCI 632 help 633 Select to build a kernel capable of supporting Intel MID (Mobile 634 Internet Device) platform systems which do not have the PCI legacy 635 interfaces. If you are building for a PC class system say N here. 636 637 Intel MID platforms are based on an Intel processor and chipset which 638 consume less power than most of the x86 derivatives. 639 640config X86_INTEL_QUARK 641 bool "Intel Quark platform support" 642 depends on X86_32 643 depends on X86_EXTENDED_PLATFORM 644 depends on X86_PLATFORM_DEVICES 645 depends on X86_TSC 646 depends on PCI 647 depends on PCI_GOANY 648 depends on X86_IO_APIC 649 select IOSF_MBI 650 select INTEL_IMR 651 select COMMON_CLK 652 help 653 Select to include support for Quark X1000 SoC. 654 Say Y here if you have a Quark based system such as the Arduino 655 compatible Intel Galileo. 656 657config X86_INTEL_LPSS 658 bool "Intel Low Power Subsystem Support" 659 depends on X86 && ACPI && PCI 660 select COMMON_CLK 661 select PINCTRL 662 select IOSF_MBI 663 help 664 Select to build support for Intel Low Power Subsystem such as 665 found on Intel Lynxpoint PCH. Selecting this option enables 666 things like clock tree (common clock framework) and pincontrol 667 which are needed by the LPSS peripheral drivers. 668 669config X86_AMD_PLATFORM_DEVICE 670 bool "AMD ACPI2Platform devices support" 671 depends on ACPI 672 select COMMON_CLK 673 select PINCTRL 674 help 675 Select to interpret AMD specific ACPI device to platform device 676 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 677 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 678 implemented under PINCTRL subsystem. 679 680config IOSF_MBI 681 tristate "Intel SoC IOSF Sideband support for SoC platforms" 682 depends on PCI 683 help 684 This option enables sideband register access support for Intel SoC 685 platforms. On these platforms the IOSF sideband is used in lieu of 686 MSR's for some register accesses, mostly but not limited to thermal 687 and power. Drivers may query the availability of this device to 688 determine if they need the sideband in order to work on these 689 platforms. The sideband is available on the following SoC products. 690 This list is not meant to be exclusive. 691 - BayTrail 692 - Braswell 693 - Quark 694 695 You should say Y if you are running a kernel on one of these SoC's. 696 697config IOSF_MBI_DEBUG 698 bool "Enable IOSF sideband access through debugfs" 699 depends on IOSF_MBI && DEBUG_FS 700 help 701 Select this option to expose the IOSF sideband access registers (MCR, 702 MDR, MCRX) through debugfs to write and read register information from 703 different units on the SoC. This is most useful for obtaining device 704 state information for debug and analysis. As this is a general access 705 mechanism, users of this option would have specific knowledge of the 706 device they want to access. 707 708 If you don't require the option or are in doubt, say N. 709 710config X86_RDC321X 711 bool "RDC R-321x SoC" 712 depends on X86_32 713 depends on X86_EXTENDED_PLATFORM 714 select M486 715 select X86_REBOOTFIXUPS 716 help 717 This option is needed for RDC R-321x system-on-chip, also known 718 as R-8610-(G). 719 If you don't have one of these chips, you should say N here. 720 721config X86_32_NON_STANDARD 722 bool "Support non-standard 32-bit SMP architectures" 723 depends on X86_32 && SMP 724 depends on X86_EXTENDED_PLATFORM 725 help 726 This option compiles in the bigsmp and STA2X11 default 727 subarchitectures. It is intended for a generic binary 728 kernel. If you select them all, kernel will probe it one by 729 one and will fallback to default. 730 731# Alphabetically sorted list of Non standard 32 bit platforms 732 733config X86_SUPPORTS_MEMORY_FAILURE 734 def_bool y 735 # MCE code calls memory_failure(): 736 depends on X86_MCE 737 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 738 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 739 depends on X86_64 || !SPARSEMEM 740 select ARCH_SUPPORTS_MEMORY_FAILURE 741 742config STA2X11 743 bool "STA2X11 Companion Chip Support" 744 depends on X86_32_NON_STANDARD && PCI 745 select SWIOTLB 746 select MFD_STA2X11 747 select GPIOLIB 748 help 749 This adds support for boards based on the STA2X11 IO-Hub, 750 a.k.a. "ConneXt". The chip is used in place of the standard 751 PC chipset, so all "standard" peripherals are missing. If this 752 option is selected the kernel will still be able to boot on 753 standard PC machines. 754 755config X86_32_IRIS 756 tristate "Eurobraille/Iris poweroff module" 757 depends on X86_32 758 help 759 The Iris machines from EuroBraille do not have APM or ACPI support 760 to shut themselves down properly. A special I/O sequence is 761 needed to do so, which is what this module does at 762 kernel shutdown. 763 764 This is only for Iris machines from EuroBraille. 765 766 If unused, say N. 767 768config SCHED_OMIT_FRAME_POINTER 769 def_bool y 770 prompt "Single-depth WCHAN output" 771 depends on X86 772 help 773 Calculate simpler /proc/<PID>/wchan values. If this option 774 is disabled then wchan values will recurse back to the 775 caller function. This provides more accurate wchan values, 776 at the expense of slightly more scheduling overhead. 777 778 If in doubt, say "Y". 779 780menuconfig HYPERVISOR_GUEST 781 bool "Linux guest support" 782 help 783 Say Y here to enable options for running Linux under various hyper- 784 visors. This option enables basic hypervisor detection and platform 785 setup. 786 787 If you say N, all options in this submenu will be skipped and 788 disabled, and Linux guest support won't be built in. 789 790if HYPERVISOR_GUEST 791 792config PARAVIRT 793 bool "Enable paravirtualization code" 794 depends on HAVE_STATIC_CALL 795 help 796 This changes the kernel so it can modify itself when it is run 797 under a hypervisor, potentially improving performance significantly 798 over full virtualization. However, when run without a hypervisor 799 the kernel is theoretically slower and slightly larger. 800 801config PARAVIRT_XXL 802 bool 803 804config PARAVIRT_DEBUG 805 bool "paravirt-ops debugging" 806 depends on PARAVIRT && DEBUG_KERNEL 807 help 808 Enable to debug paravirt_ops internals. Specifically, BUG if 809 a paravirt_op is missing when it is called. 810 811config PARAVIRT_SPINLOCKS 812 bool "Paravirtualization layer for spinlocks" 813 depends on PARAVIRT && SMP 814 help 815 Paravirtualized spinlocks allow a pvops backend to replace the 816 spinlock implementation with something virtualization-friendly 817 (for example, block the virtual CPU rather than spinning). 818 819 It has a minimal impact on native kernels and gives a nice performance 820 benefit on paravirtualized KVM / Xen kernels. 821 822 If you are unsure how to answer this question, answer Y. 823 824config X86_HV_CALLBACK_VECTOR 825 def_bool n 826 827source "arch/x86/xen/Kconfig" 828 829config KVM_GUEST 830 bool "KVM Guest support (including kvmclock)" 831 depends on PARAVIRT 832 select PARAVIRT_CLOCK 833 select ARCH_CPUIDLE_HALTPOLL 834 select X86_HV_CALLBACK_VECTOR 835 default y 836 help 837 This option enables various optimizations for running under the KVM 838 hypervisor. It includes a paravirtualized clock, so that instead 839 of relying on a PIT (or probably other) emulation by the 840 underlying device model, the host provides the guest with 841 timing infrastructure such as time of day, and system time 842 843config ARCH_CPUIDLE_HALTPOLL 844 def_bool n 845 prompt "Disable host haltpoll when loading haltpoll driver" 846 help 847 If virtualized under KVM, disable host haltpoll. 848 849config PVH 850 bool "Support for running PVH guests" 851 help 852 This option enables the PVH entry point for guest virtual machines 853 as specified in the x86/HVM direct boot ABI. 854 855config PARAVIRT_TIME_ACCOUNTING 856 bool "Paravirtual steal time accounting" 857 depends on PARAVIRT 858 help 859 Select this option to enable fine granularity task steal time 860 accounting. Time spent executing other tasks in parallel with 861 the current vCPU is discounted from the vCPU power. To account for 862 that, there can be a small performance impact. 863 864 If in doubt, say N here. 865 866config PARAVIRT_CLOCK 867 bool 868 869config JAILHOUSE_GUEST 870 bool "Jailhouse non-root cell support" 871 depends on X86_64 && PCI 872 select X86_PM_TIMER 873 help 874 This option allows to run Linux as guest in a Jailhouse non-root 875 cell. You can leave this option disabled if you only want to start 876 Jailhouse and run Linux afterwards in the root cell. 877 878config ACRN_GUEST 879 bool "ACRN Guest support" 880 depends on X86_64 881 select X86_HV_CALLBACK_VECTOR 882 help 883 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 884 a flexible, lightweight reference open-source hypervisor, built with 885 real-time and safety-criticality in mind. It is built for embedded 886 IOT with small footprint and real-time features. More details can be 887 found in https://projectacrn.org/. 888 889config INTEL_TDX_GUEST 890 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 891 depends on X86_64 && CPU_SUP_INTEL 892 depends on X86_X2APIC 893 depends on EFI_STUB 894 select ARCH_HAS_CC_PLATFORM 895 select X86_MEM_ENCRYPT 896 select X86_MCE 897 select UNACCEPTED_MEMORY 898 help 899 Support running as a guest under Intel TDX. Without this support, 900 the guest kernel can not boot or run under TDX. 901 TDX includes memory encryption and integrity capabilities 902 which protect the confidentiality and integrity of guest 903 memory contents and CPU state. TDX guests are protected from 904 some attacks from the VMM. 905 906endif # HYPERVISOR_GUEST 907 908source "arch/x86/Kconfig.cpu" 909 910config HPET_TIMER 911 def_bool X86_64 912 prompt "HPET Timer Support" if X86_32 913 help 914 Use the IA-PC HPET (High Precision Event Timer) to manage 915 time in preference to the PIT and RTC, if a HPET is 916 present. 917 HPET is the next generation timer replacing legacy 8254s. 918 The HPET provides a stable time base on SMP 919 systems, unlike the TSC, but it is more expensive to access, 920 as it is off-chip. The interface used is documented 921 in the HPET spec, revision 1. 922 923 You can safely choose Y here. However, HPET will only be 924 activated if the platform and the BIOS support this feature. 925 Otherwise the 8254 will be used for timing services. 926 927 Choose N to continue using the legacy 8254 timer. 928 929config HPET_EMULATE_RTC 930 def_bool y 931 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 932 933# Mark as expert because too many people got it wrong. 934# The code disables itself when not needed. 935config DMI 936 default y 937 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 938 bool "Enable DMI scanning" if EXPERT 939 help 940 Enabled scanning of DMI to identify machine quirks. Say Y 941 here unless you have verified that your setup is not 942 affected by entries in the DMI blacklist. Required by PNP 943 BIOS code. 944 945config GART_IOMMU 946 bool "Old AMD GART IOMMU support" 947 select DMA_OPS 948 select IOMMU_HELPER 949 select SWIOTLB 950 depends on X86_64 && PCI && AMD_NB 951 help 952 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 953 GART based hardware IOMMUs. 954 955 The GART supports full DMA access for devices with 32-bit access 956 limitations, on systems with more than 3 GB. This is usually needed 957 for USB, sound, many IDE/SATA chipsets and some other devices. 958 959 Newer systems typically have a modern AMD IOMMU, supported via 960 the CONFIG_AMD_IOMMU=y config option. 961 962 In normal configurations this driver is only active when needed: 963 there's more than 3 GB of memory and the system contains a 964 32-bit limited device. 965 966 If unsure, say Y. 967 968config BOOT_VESA_SUPPORT 969 bool 970 help 971 If true, at least one selected framebuffer driver can take advantage 972 of VESA video modes set at an early boot stage via the vga= parameter. 973 974config MAXSMP 975 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 976 depends on X86_64 && SMP && DEBUG_KERNEL 977 select CPUMASK_OFFSTACK 978 help 979 Enable maximum number of CPUS and NUMA Nodes for this architecture. 980 If unsure, say N. 981 982# 983# The maximum number of CPUs supported: 984# 985# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 986# and which can be configured interactively in the 987# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 988# 989# The ranges are different on 32-bit and 64-bit kernels, depending on 990# hardware capabilities and scalability features of the kernel. 991# 992# ( If MAXSMP is enabled we just use the highest possible value and disable 993# interactive configuration. ) 994# 995 996config NR_CPUS_RANGE_BEGIN 997 int 998 default NR_CPUS_RANGE_END if MAXSMP 999 default 1 if !SMP 1000 default 2 1001 1002config NR_CPUS_RANGE_END 1003 int 1004 depends on X86_32 1005 default 64 if SMP && X86_BIGSMP 1006 default 8 if SMP && !X86_BIGSMP 1007 default 1 if !SMP 1008 1009config NR_CPUS_RANGE_END 1010 int 1011 depends on X86_64 1012 default 8192 if SMP && CPUMASK_OFFSTACK 1013 default 512 if SMP && !CPUMASK_OFFSTACK 1014 default 1 if !SMP 1015 1016config NR_CPUS_DEFAULT 1017 int 1018 depends on X86_32 1019 default 32 if X86_BIGSMP 1020 default 8 if SMP 1021 default 1 if !SMP 1022 1023config NR_CPUS_DEFAULT 1024 int 1025 depends on X86_64 1026 default 8192 if MAXSMP 1027 default 64 if SMP 1028 default 1 if !SMP 1029 1030config NR_CPUS 1031 int "Maximum number of CPUs" if SMP && !MAXSMP 1032 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1033 default NR_CPUS_DEFAULT 1034 help 1035 This allows you to specify the maximum number of CPUs which this 1036 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1037 supported value is 8192, otherwise the maximum value is 512. The 1038 minimum value which makes sense is 2. 1039 1040 This is purely to save memory: each supported CPU adds about 8KB 1041 to the kernel image. 1042 1043config SCHED_CLUSTER 1044 bool "Cluster scheduler support" 1045 depends on SMP 1046 default y 1047 help 1048 Cluster scheduler support improves the CPU scheduler's decision 1049 making when dealing with machines that have clusters of CPUs. 1050 Cluster usually means a couple of CPUs which are placed closely 1051 by sharing mid-level caches, last-level cache tags or internal 1052 busses. 1053 1054config SCHED_SMT 1055 def_bool y if SMP 1056 1057config SCHED_MC 1058 def_bool y 1059 prompt "Multi-core scheduler support" 1060 depends on SMP 1061 help 1062 Multi-core scheduler support improves the CPU scheduler's decision 1063 making when dealing with multi-core CPU chips at a cost of slightly 1064 increased overhead in some places. If unsure say N here. 1065 1066config SCHED_MC_PRIO 1067 bool "CPU core priorities scheduler support" 1068 depends on SCHED_MC 1069 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1070 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1071 select CPU_FREQ 1072 default y 1073 help 1074 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1075 core ordering determined at manufacturing time, which allows 1076 certain cores to reach higher turbo frequencies (when running 1077 single threaded workloads) than others. 1078 1079 Enabling this kernel feature teaches the scheduler about 1080 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1081 scheduler's CPU selection logic accordingly, so that higher 1082 overall system performance can be achieved. 1083 1084 This feature will have no effect on CPUs without this feature. 1085 1086 If unsure say Y here. 1087 1088config UP_LATE_INIT 1089 def_bool y 1090 depends on !SMP && X86_LOCAL_APIC 1091 1092config X86_UP_APIC 1093 bool "Local APIC support on uniprocessors" if !PCI_MSI 1094 default PCI_MSI 1095 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1096 help 1097 A local APIC (Advanced Programmable Interrupt Controller) is an 1098 integrated interrupt controller in the CPU. If you have a single-CPU 1099 system which has a processor with a local APIC, you can say Y here to 1100 enable and use it. If you say Y here even though your machine doesn't 1101 have a local APIC, then the kernel will still run with no slowdown at 1102 all. The local APIC supports CPU-generated self-interrupts (timer, 1103 performance counters), and the NMI watchdog which detects hard 1104 lockups. 1105 1106config X86_UP_IOAPIC 1107 bool "IO-APIC support on uniprocessors" 1108 depends on X86_UP_APIC 1109 help 1110 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1111 SMP-capable replacement for PC-style interrupt controllers. Most 1112 SMP systems and many recent uniprocessor systems have one. 1113 1114 If you have a single-CPU system with an IO-APIC, you can say Y here 1115 to use it. If you say Y here even though your machine doesn't have 1116 an IO-APIC, then the kernel will still run with no slowdown at all. 1117 1118config X86_LOCAL_APIC 1119 def_bool y 1120 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1121 select IRQ_DOMAIN_HIERARCHY 1122 1123config ACPI_MADT_WAKEUP 1124 def_bool y 1125 depends on X86_64 1126 depends on ACPI 1127 depends on SMP 1128 depends on X86_LOCAL_APIC 1129 1130config X86_IO_APIC 1131 def_bool y 1132 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1133 1134config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1135 bool "Reroute for broken boot IRQs" 1136 depends on X86_IO_APIC 1137 help 1138 This option enables a workaround that fixes a source of 1139 spurious interrupts. This is recommended when threaded 1140 interrupt handling is used on systems where the generation of 1141 superfluous "boot interrupts" cannot be disabled. 1142 1143 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1144 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1145 kernel does during interrupt handling). On chipsets where this 1146 boot IRQ generation cannot be disabled, this workaround keeps 1147 the original IRQ line masked so that only the equivalent "boot 1148 IRQ" is delivered to the CPUs. The workaround also tells the 1149 kernel to set up the IRQ handler on the boot IRQ line. In this 1150 way only one interrupt is delivered to the kernel. Otherwise 1151 the spurious second interrupt may cause the kernel to bring 1152 down (vital) interrupt lines. 1153 1154 Only affects "broken" chipsets. Interrupt sharing may be 1155 increased on these systems. 1156 1157config X86_MCE 1158 bool "Machine Check / overheating reporting" 1159 select GENERIC_ALLOCATOR 1160 default y 1161 help 1162 Machine Check support allows the processor to notify the 1163 kernel if it detects a problem (e.g. overheating, data corruption). 1164 The action the kernel takes depends on the severity of the problem, 1165 ranging from warning messages to halting the machine. 1166 1167config X86_MCELOG_LEGACY 1168 bool "Support for deprecated /dev/mcelog character device" 1169 depends on X86_MCE 1170 help 1171 Enable support for /dev/mcelog which is needed by the old mcelog 1172 userspace logging daemon. Consider switching to the new generation 1173 rasdaemon solution. 1174 1175config X86_MCE_INTEL 1176 def_bool y 1177 prompt "Intel MCE features" 1178 depends on X86_MCE && X86_LOCAL_APIC 1179 help 1180 Additional support for intel specific MCE features such as 1181 the thermal monitor. 1182 1183config X86_MCE_AMD 1184 def_bool y 1185 prompt "AMD MCE features" 1186 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1187 help 1188 Additional support for AMD specific MCE features such as 1189 the DRAM Error Threshold. 1190 1191config X86_ANCIENT_MCE 1192 bool "Support for old Pentium 5 / WinChip machine checks" 1193 depends on X86_32 && X86_MCE 1194 help 1195 Include support for machine check handling on old Pentium 5 or WinChip 1196 systems. These typically need to be enabled explicitly on the command 1197 line. 1198 1199config X86_MCE_THRESHOLD 1200 depends on X86_MCE_AMD || X86_MCE_INTEL 1201 def_bool y 1202 1203config X86_MCE_INJECT 1204 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1205 tristate "Machine check injector support" 1206 help 1207 Provide support for injecting machine checks for testing purposes. 1208 If you don't know what a machine check is and you don't do kernel 1209 QA it is safe to say n. 1210 1211source "arch/x86/events/Kconfig" 1212 1213config X86_LEGACY_VM86 1214 bool "Legacy VM86 support" 1215 depends on X86_32 1216 help 1217 This option allows user programs to put the CPU into V8086 1218 mode, which is an 80286-era approximation of 16-bit real mode. 1219 1220 Some very old versions of X and/or vbetool require this option 1221 for user mode setting. Similarly, DOSEMU will use it if 1222 available to accelerate real mode DOS programs. However, any 1223 recent version of DOSEMU, X, or vbetool should be fully 1224 functional even without kernel VM86 support, as they will all 1225 fall back to software emulation. Nevertheless, if you are using 1226 a 16-bit DOS program where 16-bit performance matters, vm86 1227 mode might be faster than emulation and you might want to 1228 enable this option. 1229 1230 Note that any app that works on a 64-bit kernel is unlikely to 1231 need this option, as 64-bit kernels don't, and can't, support 1232 V8086 mode. This option is also unrelated to 16-bit protected 1233 mode and is not needed to run most 16-bit programs under Wine. 1234 1235 Enabling this option increases the complexity of the kernel 1236 and slows down exception handling a tiny bit. 1237 1238 If unsure, say N here. 1239 1240config VM86 1241 bool 1242 default X86_LEGACY_VM86 1243 1244config X86_16BIT 1245 bool "Enable support for 16-bit segments" if EXPERT 1246 default y 1247 depends on MODIFY_LDT_SYSCALL 1248 help 1249 This option is required by programs like Wine to run 16-bit 1250 protected mode legacy code on x86 processors. Disabling 1251 this option saves about 300 bytes on i386, or around 6K text 1252 plus 16K runtime memory on x86-64, 1253 1254config X86_ESPFIX32 1255 def_bool y 1256 depends on X86_16BIT && X86_32 1257 1258config X86_ESPFIX64 1259 def_bool y 1260 depends on X86_16BIT && X86_64 1261 1262config X86_VSYSCALL_EMULATION 1263 bool "Enable vsyscall emulation" if EXPERT 1264 default y 1265 depends on X86_64 1266 help 1267 This enables emulation of the legacy vsyscall page. Disabling 1268 it is roughly equivalent to booting with vsyscall=none, except 1269 that it will also disable the helpful warning if a program 1270 tries to use a vsyscall. With this option set to N, offending 1271 programs will just segfault, citing addresses of the form 1272 0xffffffffff600?00. 1273 1274 This option is required by many programs built before 2013, and 1275 care should be used even with newer programs if set to N. 1276 1277 Disabling this option saves about 7K of kernel size and 1278 possibly 4K of additional runtime pagetable memory. 1279 1280config X86_IOPL_IOPERM 1281 bool "IOPERM and IOPL Emulation" 1282 default y 1283 help 1284 This enables the ioperm() and iopl() syscalls which are necessary 1285 for legacy applications. 1286 1287 Legacy IOPL support is an overbroad mechanism which allows user 1288 space aside of accessing all 65536 I/O ports also to disable 1289 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1290 capabilities and permission from potentially active security 1291 modules. 1292 1293 The emulation restricts the functionality of the syscall to 1294 only allowing the full range I/O port access, but prevents the 1295 ability to disable interrupts from user space which would be 1296 granted if the hardware IOPL mechanism would be used. 1297 1298config TOSHIBA 1299 tristate "Toshiba Laptop support" 1300 depends on X86_32 1301 help 1302 This adds a driver to safely access the System Management Mode of 1303 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1304 not work on models with a Phoenix BIOS. The System Management Mode 1305 is used to set the BIOS and power saving options on Toshiba portables. 1306 1307 For information on utilities to make use of this driver see the 1308 Toshiba Linux utilities web site at: 1309 <http://www.buzzard.org.uk/toshiba/>. 1310 1311 Say Y if you intend to run this kernel on a Toshiba portable. 1312 Say N otherwise. 1313 1314config X86_REBOOTFIXUPS 1315 bool "Enable X86 board specific fixups for reboot" 1316 depends on X86_32 1317 help 1318 This enables chipset and/or board specific fixups to be done 1319 in order to get reboot to work correctly. This is only needed on 1320 some combinations of hardware and BIOS. The symptom, for which 1321 this config is intended, is when reboot ends with a stalled/hung 1322 system. 1323 1324 Currently, the only fixup is for the Geode machines using 1325 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1326 1327 Say Y if you want to enable the fixup. Currently, it's safe to 1328 enable this option even if you don't need it. 1329 Say N otherwise. 1330 1331config MICROCODE 1332 def_bool y 1333 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1334 1335config MICROCODE_INITRD32 1336 def_bool y 1337 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1338 1339config MICROCODE_LATE_LOADING 1340 bool "Late microcode loading (DANGEROUS)" 1341 default n 1342 depends on MICROCODE && SMP 1343 help 1344 Loading microcode late, when the system is up and executing instructions 1345 is a tricky business and should be avoided if possible. Just the sequence 1346 of synchronizing all cores and SMT threads is one fragile dance which does 1347 not guarantee that cores might not softlock after the loading. Therefore, 1348 use this at your own risk. Late loading taints the kernel unless the 1349 microcode header indicates that it is safe for late loading via the 1350 minimal revision check. This minimal revision check can be enforced on 1351 the kernel command line with "microcode.minrev=Y". 1352 1353config MICROCODE_LATE_FORCE_MINREV 1354 bool "Enforce late microcode loading minimal revision check" 1355 default n 1356 depends on MICROCODE_LATE_LOADING 1357 help 1358 To prevent that users load microcode late which modifies already 1359 in use features, newer microcode patches have a minimum revision field 1360 in the microcode header, which tells the kernel which minimum 1361 revision must be active in the CPU to safely load that new microcode 1362 late into the running system. If disabled the check will not 1363 be enforced but the kernel will be tainted when the minimal 1364 revision check fails. 1365 1366 This minimal revision check can also be controlled via the 1367 "microcode.minrev" parameter on the kernel command line. 1368 1369 If unsure say Y. 1370 1371config X86_MSR 1372 tristate "/dev/cpu/*/msr - Model-specific register support" 1373 help 1374 This device gives privileged processes access to the x86 1375 Model-Specific Registers (MSRs). It is a character device with 1376 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1377 MSR accesses are directed to a specific CPU on multi-processor 1378 systems. 1379 1380config X86_CPUID 1381 tristate "/dev/cpu/*/cpuid - CPU information support" 1382 help 1383 This device gives processes access to the x86 CPUID instruction to 1384 be executed on a specific processor. It is a character device 1385 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1386 /dev/cpu/31/cpuid. 1387 1388choice 1389 prompt "High Memory Support" 1390 default HIGHMEM4G 1391 depends on X86_32 1392 1393config NOHIGHMEM 1394 bool "off" 1395 help 1396 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1397 However, the address space of 32-bit x86 processors is only 4 1398 Gigabytes large. That means that, if you have a large amount of 1399 physical memory, not all of it can be "permanently mapped" by the 1400 kernel. The physical memory that's not permanently mapped is called 1401 "high memory". 1402 1403 If you are compiling a kernel which will never run on a machine with 1404 more than 1 Gigabyte total physical RAM, answer "off" here (default 1405 choice and suitable for most users). This will result in a "3GB/1GB" 1406 split: 3GB are mapped so that each process sees a 3GB virtual memory 1407 space and the remaining part of the 4GB virtual memory space is used 1408 by the kernel to permanently map as much physical memory as 1409 possible. 1410 1411 If the machine has between 1 and 4 Gigabytes physical RAM, then 1412 answer "4GB" here. 1413 1414 If more than 4 Gigabytes is used then answer "64GB" here. This 1415 selection turns Intel PAE (Physical Address Extension) mode on. 1416 PAE implements 3-level paging on IA32 processors. PAE is fully 1417 supported by Linux, PAE mode is implemented on all recent Intel 1418 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1419 then the kernel will not boot on CPUs that don't support PAE! 1420 1421 The actual amount of total physical memory will either be 1422 auto detected or can be forced by using a kernel command line option 1423 such as "mem=256M". (Try "man bootparam" or see the documentation of 1424 your boot loader (lilo or loadlin) about how to pass options to the 1425 kernel at boot time.) 1426 1427 If unsure, say "off". 1428 1429config HIGHMEM4G 1430 bool "4GB" 1431 help 1432 Select this if you have a 32-bit processor and between 1 and 4 1433 gigabytes of physical RAM. 1434 1435config HIGHMEM64G 1436 bool "64GB" 1437 depends on X86_HAVE_PAE 1438 select X86_PAE 1439 help 1440 Select this if you have a 32-bit processor and more than 4 1441 gigabytes of physical RAM. 1442 1443endchoice 1444 1445choice 1446 prompt "Memory split" if EXPERT 1447 default VMSPLIT_3G 1448 depends on X86_32 1449 help 1450 Select the desired split between kernel and user memory. 1451 1452 If the address range available to the kernel is less than the 1453 physical memory installed, the remaining memory will be available 1454 as "high memory". Accessing high memory is a little more costly 1455 than low memory, as it needs to be mapped into the kernel first. 1456 Note that increasing the kernel address space limits the range 1457 available to user programs, making the address space there 1458 tighter. Selecting anything other than the default 3G/1G split 1459 will also likely make your kernel incompatible with binary-only 1460 kernel modules. 1461 1462 If you are not absolutely sure what you are doing, leave this 1463 option alone! 1464 1465 config VMSPLIT_3G 1466 bool "3G/1G user/kernel split" 1467 config VMSPLIT_3G_OPT 1468 depends on !X86_PAE 1469 bool "3G/1G user/kernel split (for full 1G low memory)" 1470 config VMSPLIT_2G 1471 bool "2G/2G user/kernel split" 1472 config VMSPLIT_2G_OPT 1473 depends on !X86_PAE 1474 bool "2G/2G user/kernel split (for full 2G low memory)" 1475 config VMSPLIT_1G 1476 bool "1G/3G user/kernel split" 1477endchoice 1478 1479config PAGE_OFFSET 1480 hex 1481 default 0xB0000000 if VMSPLIT_3G_OPT 1482 default 0x80000000 if VMSPLIT_2G 1483 default 0x78000000 if VMSPLIT_2G_OPT 1484 default 0x40000000 if VMSPLIT_1G 1485 default 0xC0000000 1486 depends on X86_32 1487 1488config HIGHMEM 1489 def_bool y 1490 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1491 1492config X86_PAE 1493 bool "PAE (Physical Address Extension) Support" 1494 depends on X86_32 && X86_HAVE_PAE 1495 select PHYS_ADDR_T_64BIT 1496 select SWIOTLB 1497 help 1498 PAE is required for NX support, and furthermore enables 1499 larger swapspace support for non-overcommit purposes. It 1500 has the cost of more pagetable lookup overhead, and also 1501 consumes more pagetable space per process. 1502 1503config X86_5LEVEL 1504 bool "Enable 5-level page tables support" 1505 default y 1506 select DYNAMIC_MEMORY_LAYOUT 1507 select SPARSEMEM_VMEMMAP 1508 depends on X86_64 1509 help 1510 5-level paging enables access to larger address space: 1511 up to 128 PiB of virtual address space and 4 PiB of 1512 physical address space. 1513 1514 It will be supported by future Intel CPUs. 1515 1516 A kernel with the option enabled can be booted on machines that 1517 support 4- or 5-level paging. 1518 1519 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1520 information. 1521 1522 Say N if unsure. 1523 1524config X86_DIRECT_GBPAGES 1525 def_bool y 1526 depends on X86_64 1527 help 1528 Certain kernel features effectively disable kernel 1529 linear 1 GB mappings (even if the CPU otherwise 1530 supports them), so don't confuse the user by printing 1531 that we have them enabled. 1532 1533config X86_CPA_STATISTICS 1534 bool "Enable statistic for Change Page Attribute" 1535 depends on DEBUG_FS 1536 help 1537 Expose statistics about the Change Page Attribute mechanism, which 1538 helps to determine the effectiveness of preserving large and huge 1539 page mappings when mapping protections are changed. 1540 1541config X86_MEM_ENCRYPT 1542 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1543 select DYNAMIC_PHYSICAL_MASK 1544 def_bool n 1545 1546config AMD_MEM_ENCRYPT 1547 bool "AMD Secure Memory Encryption (SME) support" 1548 depends on X86_64 && CPU_SUP_AMD 1549 depends on EFI_STUB 1550 select DMA_COHERENT_POOL 1551 select ARCH_USE_MEMREMAP_PROT 1552 select INSTRUCTION_DECODER 1553 select ARCH_HAS_CC_PLATFORM 1554 select X86_MEM_ENCRYPT 1555 select UNACCEPTED_MEMORY 1556 help 1557 Say yes to enable support for the encryption of system memory. 1558 This requires an AMD processor that supports Secure Memory 1559 Encryption (SME). 1560 1561# Common NUMA Features 1562config NUMA 1563 bool "NUMA Memory Allocation and Scheduler Support" 1564 depends on SMP 1565 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1566 default y if X86_BIGSMP 1567 select USE_PERCPU_NUMA_NODE_ID 1568 select OF_NUMA if OF 1569 help 1570 Enable NUMA (Non-Uniform Memory Access) support. 1571 1572 The kernel will try to allocate memory used by a CPU on the 1573 local memory controller of the CPU and add some more 1574 NUMA awareness to the kernel. 1575 1576 For 64-bit this is recommended if the system is Intel Core i7 1577 (or later), AMD Opteron, or EM64T NUMA. 1578 1579 For 32-bit this is only needed if you boot a 32-bit 1580 kernel on a 64-bit NUMA platform. 1581 1582 Otherwise, you should say N. 1583 1584config AMD_NUMA 1585 def_bool y 1586 prompt "Old style AMD Opteron NUMA detection" 1587 depends on X86_64 && NUMA && PCI 1588 help 1589 Enable AMD NUMA node topology detection. You should say Y here if 1590 you have a multi processor AMD system. This uses an old method to 1591 read the NUMA configuration directly from the builtin Northbridge 1592 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1593 which also takes priority if both are compiled in. 1594 1595config X86_64_ACPI_NUMA 1596 def_bool y 1597 prompt "ACPI NUMA detection" 1598 depends on X86_64 && NUMA && ACPI && PCI 1599 select ACPI_NUMA 1600 help 1601 Enable ACPI SRAT based node topology detection. 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 select ARCH_USES_PG_ARCH_2 1803 help 1804 Use PAT attributes to setup page level cache control. 1805 1806 PATs are the modern equivalents of MTRRs and are much more 1807 flexible than MTRRs. 1808 1809 Say N here if you see bootup problems (boot crash, boot hang, 1810 spontaneous reboots) or a non-working video driver. 1811 1812 If unsure, say Y. 1813 1814config X86_UMIP 1815 def_bool y 1816 prompt "User Mode Instruction Prevention" if EXPERT 1817 help 1818 User Mode Instruction Prevention (UMIP) is a security feature in 1819 some x86 processors. If enabled, a general protection fault is 1820 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1821 executed in user mode. These instructions unnecessarily expose 1822 information about the hardware state. 1823 1824 The vast majority of applications do not use these instructions. 1825 For the very few that do, software emulation is provided in 1826 specific cases in protected and virtual-8086 modes. Emulated 1827 results are dummy. 1828 1829config CC_HAS_IBT 1830 # GCC >= 9 and binutils >= 2.29 1831 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1832 # Clang/LLVM >= 14 1833 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1834 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1835 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1836 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1837 $(as-instr,endbr64) 1838 1839config X86_CET 1840 def_bool n 1841 help 1842 CET features configured (Shadow stack or IBT) 1843 1844config X86_KERNEL_IBT 1845 prompt "Indirect Branch Tracking" 1846 def_bool y 1847 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1848 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1849 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1850 select OBJTOOL 1851 select X86_CET 1852 help 1853 Build the kernel with support for Indirect Branch Tracking, a 1854 hardware support course-grain forward-edge Control Flow Integrity 1855 protection. It enforces that all indirect calls must land on 1856 an ENDBR instruction, as such, the compiler will instrument the 1857 code with them to make this happen. 1858 1859 In addition to building the kernel with IBT, seal all functions that 1860 are not indirect call targets, avoiding them ever becoming one. 1861 1862 This requires LTO like objtool runs and will slow down the build. It 1863 does significantly reduce the number of ENDBR instructions in the 1864 kernel image. 1865 1866config X86_INTEL_MEMORY_PROTECTION_KEYS 1867 prompt "Memory Protection Keys" 1868 def_bool y 1869 # Note: only available in 64-bit mode 1870 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1871 select ARCH_USES_HIGH_VMA_FLAGS 1872 select ARCH_HAS_PKEYS 1873 help 1874 Memory Protection Keys provides a mechanism for enforcing 1875 page-based protections, but without requiring modification of the 1876 page tables when an application changes protection domains. 1877 1878 For details, see Documentation/core-api/protection-keys.rst 1879 1880 If unsure, say y. 1881 1882choice 1883 prompt "TSX enable mode" 1884 depends on CPU_SUP_INTEL 1885 default X86_INTEL_TSX_MODE_OFF 1886 help 1887 Intel's TSX (Transactional Synchronization Extensions) feature 1888 allows to optimize locking protocols through lock elision which 1889 can lead to a noticeable performance boost. 1890 1891 On the other hand it has been shown that TSX can be exploited 1892 to form side channel attacks (e.g. TAA) and chances are there 1893 will be more of those attacks discovered in the future. 1894 1895 Therefore TSX is not enabled by default (aka tsx=off). An admin 1896 might override this decision by tsx=on the command line parameter. 1897 Even with TSX enabled, the kernel will attempt to enable the best 1898 possible TAA mitigation setting depending on the microcode available 1899 for the particular machine. 1900 1901 This option allows to set the default tsx mode between tsx=on, =off 1902 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1903 details. 1904 1905 Say off if not sure, auto if TSX is in use but it should be used on safe 1906 platforms or on if TSX is in use and the security aspect of tsx is not 1907 relevant. 1908 1909config X86_INTEL_TSX_MODE_OFF 1910 bool "off" 1911 help 1912 TSX is disabled if possible - equals to tsx=off command line parameter. 1913 1914config X86_INTEL_TSX_MODE_ON 1915 bool "on" 1916 help 1917 TSX is always enabled on TSX capable HW - equals the tsx=on command 1918 line parameter. 1919 1920config X86_INTEL_TSX_MODE_AUTO 1921 bool "auto" 1922 help 1923 TSX is enabled on TSX capable HW that is believed to be safe against 1924 side channel attacks- equals the tsx=auto command line parameter. 1925endchoice 1926 1927config X86_SGX 1928 bool "Software Guard eXtensions (SGX)" 1929 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1930 depends on CRYPTO=y 1931 depends on CRYPTO_SHA256=y 1932 select MMU_NOTIFIER 1933 select NUMA_KEEP_MEMINFO if NUMA 1934 select XARRAY_MULTI 1935 help 1936 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1937 that can be used by applications to set aside private regions of code 1938 and data, referred to as enclaves. An enclave's private memory can 1939 only be accessed by code running within the enclave. Accesses from 1940 outside the enclave, including other enclaves, are disallowed by 1941 hardware. 1942 1943 If unsure, say N. 1944 1945config X86_USER_SHADOW_STACK 1946 bool "X86 userspace shadow stack" 1947 depends on AS_WRUSS 1948 depends on X86_64 1949 select ARCH_USES_HIGH_VMA_FLAGS 1950 select X86_CET 1951 help 1952 Shadow stack protection is a hardware feature that detects function 1953 return address corruption. This helps mitigate ROP attacks. 1954 Applications must be enabled to use it, and old userspace does not 1955 get protection "for free". 1956 1957 CPUs supporting shadow stacks were first released in 2020. 1958 1959 See Documentation/arch/x86/shstk.rst for more information. 1960 1961 If unsure, say N. 1962 1963config INTEL_TDX_HOST 1964 bool "Intel Trust Domain Extensions (TDX) host support" 1965 depends on CPU_SUP_INTEL 1966 depends on X86_64 1967 depends on KVM_INTEL 1968 depends on X86_X2APIC 1969 select ARCH_KEEP_MEMBLOCK 1970 depends on CONTIG_ALLOC 1971 depends on !KEXEC_CORE 1972 depends on X86_MCE 1973 help 1974 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1975 host and certain physical attacks. This option enables necessary TDX 1976 support in the host kernel to run confidential VMs. 1977 1978 If unsure, say N. 1979 1980config EFI 1981 bool "EFI runtime service support" 1982 depends on ACPI 1983 select UCS2_STRING 1984 select EFI_RUNTIME_WRAPPERS 1985 select ARCH_USE_MEMREMAP_PROT 1986 select EFI_RUNTIME_MAP if KEXEC_CORE 1987 help 1988 This enables the kernel to use EFI runtime services that are 1989 available (such as the EFI variable services). 1990 1991 This option is only useful on systems that have EFI firmware. 1992 In addition, you should use the latest ELILO loader available 1993 at <http://elilo.sourceforge.net> in order to take advantage 1994 of EFI runtime services. However, even with this option, the 1995 resultant kernel should continue to boot on existing non-EFI 1996 platforms. 1997 1998config EFI_STUB 1999 bool "EFI stub support" 2000 depends on EFI 2001 select RELOCATABLE 2002 help 2003 This kernel feature allows a bzImage to be loaded directly 2004 by EFI firmware without the use of a bootloader. 2005 2006 See Documentation/admin-guide/efi-stub.rst for more information. 2007 2008config EFI_HANDOVER_PROTOCOL 2009 bool "EFI handover protocol (DEPRECATED)" 2010 depends on EFI_STUB 2011 default y 2012 help 2013 Select this in order to include support for the deprecated EFI 2014 handover protocol, which defines alternative entry points into the 2015 EFI stub. This is a practice that has no basis in the UEFI 2016 specification, and requires a priori knowledge on the part of the 2017 bootloader about Linux/x86 specific ways of passing the command line 2018 and initrd, and where in memory those assets may be loaded. 2019 2020 If in doubt, say Y. Even though the corresponding support is not 2021 present in upstream GRUB or other bootloaders, most distros build 2022 GRUB with numerous downstream patches applied, and may rely on the 2023 handover protocol as as result. 2024 2025config EFI_MIXED 2026 bool "EFI mixed-mode support" 2027 depends on EFI_STUB && X86_64 2028 help 2029 Enabling this feature allows a 64-bit kernel to be booted 2030 on a 32-bit firmware, provided that your CPU supports 64-bit 2031 mode. 2032 2033 Note that it is not possible to boot a mixed-mode enabled 2034 kernel via the EFI boot stub - a bootloader that supports 2035 the EFI handover protocol must be used. 2036 2037 If unsure, say N. 2038 2039config EFI_RUNTIME_MAP 2040 bool "Export EFI runtime maps to sysfs" if EXPERT 2041 depends on EFI 2042 help 2043 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2044 That memory map is required by the 2nd kernel to set up EFI virtual 2045 mappings after kexec, but can also be used for debugging purposes. 2046 2047 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2048 2049source "kernel/Kconfig.hz" 2050 2051config ARCH_SUPPORTS_KEXEC 2052 def_bool y 2053 2054config ARCH_SUPPORTS_KEXEC_FILE 2055 def_bool X86_64 2056 2057config ARCH_SELECTS_KEXEC_FILE 2058 def_bool y 2059 depends on KEXEC_FILE 2060 select HAVE_IMA_KEXEC if IMA 2061 2062config ARCH_SUPPORTS_KEXEC_PURGATORY 2063 def_bool y 2064 2065config ARCH_SUPPORTS_KEXEC_SIG 2066 def_bool y 2067 2068config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2069 def_bool y 2070 2071config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2072 def_bool y 2073 2074config ARCH_SUPPORTS_KEXEC_JUMP 2075 def_bool y 2076 2077config ARCH_SUPPORTS_CRASH_DUMP 2078 def_bool X86_64 || (X86_32 && HIGHMEM) 2079 2080config ARCH_SUPPORTS_CRASH_HOTPLUG 2081 def_bool y 2082 2083config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2084 def_bool CRASH_RESERVE 2085 2086config PHYSICAL_START 2087 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2088 default "0x1000000" 2089 help 2090 This gives the physical address where the kernel is loaded. 2091 2092 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2093 will decompress itself to above physical address and run from there. 2094 Otherwise, bzImage will run from the address where it has been loaded 2095 by the boot loader. The only exception is if it is loaded below the 2096 above physical address, in which case it will relocate itself there. 2097 2098 In normal kdump cases one does not have to set/change this option 2099 as now bzImage can be compiled as a completely relocatable image 2100 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2101 address. This option is mainly useful for the folks who don't want 2102 to use a bzImage for capturing the crash dump and want to use a 2103 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2104 to be specifically compiled to run from a specific memory area 2105 (normally a reserved region) and this option comes handy. 2106 2107 So if you are using bzImage for capturing the crash dump, 2108 leave the value here unchanged to 0x1000000 and set 2109 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2110 for capturing the crash dump change this value to start of 2111 the reserved region. In other words, it can be set based on 2112 the "X" value as specified in the "crashkernel=YM@XM" 2113 command line boot parameter passed to the panic-ed 2114 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2115 for more details about crash dumps. 2116 2117 Usage of bzImage for capturing the crash dump is recommended as 2118 one does not have to build two kernels. Same kernel can be used 2119 as production kernel and capture kernel. Above option should have 2120 gone away after relocatable bzImage support is introduced. But it 2121 is present because there are users out there who continue to use 2122 vmlinux for dump capture. This option should go away down the 2123 line. 2124 2125 Don't change this unless you know what you are doing. 2126 2127config RELOCATABLE 2128 bool "Build a relocatable kernel" 2129 default y 2130 help 2131 This builds a kernel image that retains relocation information 2132 so it can be loaded someplace besides the default 1MB. 2133 The relocations tend to make the kernel binary about 10% larger, 2134 but are discarded at runtime. 2135 2136 One use is for the kexec on panic case where the recovery kernel 2137 must live at a different physical address than the primary 2138 kernel. 2139 2140 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2141 it has been loaded at and the compile time physical address 2142 (CONFIG_PHYSICAL_START) is used as the minimum location. 2143 2144config RANDOMIZE_BASE 2145 bool "Randomize the address of the kernel image (KASLR)" 2146 depends on RELOCATABLE 2147 default y 2148 help 2149 In support of Kernel Address Space Layout Randomization (KASLR), 2150 this randomizes the physical address at which the kernel image 2151 is decompressed and the virtual address where the kernel 2152 image is mapped, as a security feature that deters exploit 2153 attempts relying on knowledge of the location of kernel 2154 code internals. 2155 2156 On 64-bit, the kernel physical and virtual addresses are 2157 randomized separately. The physical address will be anywhere 2158 between 16MB and the top of physical memory (up to 64TB). The 2159 virtual address will be randomized from 16MB up to 1GB (9 bits 2160 of entropy). Note that this also reduces the memory space 2161 available to kernel modules from 1.5GB to 1GB. 2162 2163 On 32-bit, the kernel physical and virtual addresses are 2164 randomized together. They will be randomized from 16MB up to 2165 512MB (8 bits of entropy). 2166 2167 Entropy is generated using the RDRAND instruction if it is 2168 supported. If RDTSC is supported, its value is mixed into 2169 the entropy pool as well. If neither RDRAND nor RDTSC are 2170 supported, then entropy is read from the i8254 timer. The 2171 usable entropy is limited by the kernel being built using 2172 2GB addressing, and that PHYSICAL_ALIGN must be at a 2173 minimum of 2MB. As a result, only 10 bits of entropy are 2174 theoretically possible, but the implementations are further 2175 limited due to memory layouts. 2176 2177 If unsure, say Y. 2178 2179# Relocation on x86 needs some additional build support 2180config X86_NEED_RELOCS 2181 def_bool y 2182 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2183 2184config PHYSICAL_ALIGN 2185 hex "Alignment value to which kernel should be aligned" 2186 default "0x200000" 2187 range 0x2000 0x1000000 if X86_32 2188 range 0x200000 0x1000000 if X86_64 2189 help 2190 This value puts the alignment restrictions on physical address 2191 where kernel is loaded and run from. Kernel is compiled for an 2192 address which meets above alignment restriction. 2193 2194 If bootloader loads the kernel at a non-aligned address and 2195 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2196 address aligned to above value and run from there. 2197 2198 If bootloader loads the kernel at a non-aligned address and 2199 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2200 load address and decompress itself to the address it has been 2201 compiled for and run from there. The address for which kernel is 2202 compiled already meets above alignment restrictions. Hence the 2203 end result is that kernel runs from a physical address meeting 2204 above alignment restrictions. 2205 2206 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2207 this value must be a multiple of 0x200000. 2208 2209 Don't change this unless you know what you are doing. 2210 2211config DYNAMIC_MEMORY_LAYOUT 2212 bool 2213 help 2214 This option makes base addresses of vmalloc and vmemmap as well as 2215 __PAGE_OFFSET movable during boot. 2216 2217config RANDOMIZE_MEMORY 2218 bool "Randomize the kernel memory sections" 2219 depends on X86_64 2220 depends on RANDOMIZE_BASE 2221 select DYNAMIC_MEMORY_LAYOUT 2222 default RANDOMIZE_BASE 2223 help 2224 Randomizes the base virtual address of kernel memory sections 2225 (physical memory mapping, vmalloc & vmemmap). This security feature 2226 makes exploits relying on predictable memory locations less reliable. 2227 2228 The order of allocations remains unchanged. Entropy is generated in 2229 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2230 configuration have in average 30,000 different possible virtual 2231 addresses for each memory section. 2232 2233 If unsure, say Y. 2234 2235config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2236 hex "Physical memory mapping padding" if EXPERT 2237 depends on RANDOMIZE_MEMORY 2238 default "0xa" if MEMORY_HOTPLUG 2239 default "0x0" 2240 range 0x1 0x40 if MEMORY_HOTPLUG 2241 range 0x0 0x40 2242 help 2243 Define the padding in terabytes added to the existing physical 2244 memory size during kernel memory randomization. It is useful 2245 for memory hotplug support but reduces the entropy available for 2246 address randomization. 2247 2248 If unsure, leave at the default value. 2249 2250config ADDRESS_MASKING 2251 bool "Linear Address Masking support" 2252 depends on X86_64 2253 help 2254 Linear Address Masking (LAM) modifies the checking that is applied 2255 to 64-bit linear addresses, allowing software to use of the 2256 untranslated address bits for metadata. 2257 2258 The capability can be used for efficient address sanitizers (ASAN) 2259 implementation and for optimizations in JITs. 2260 2261config HOTPLUG_CPU 2262 def_bool y 2263 depends on SMP 2264 2265config COMPAT_VDSO 2266 def_bool n 2267 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2268 depends on COMPAT_32 2269 help 2270 Certain buggy versions of glibc will crash if they are 2271 presented with a 32-bit vDSO that is not mapped at the address 2272 indicated in its segment table. 2273 2274 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2275 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2276 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2277 the only released version with the bug, but OpenSUSE 9 2278 contains a buggy "glibc 2.3.2". 2279 2280 The symptom of the bug is that everything crashes on startup, saying: 2281 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2282 2283 Saying Y here changes the default value of the vdso32 boot 2284 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2285 This works around the glibc bug but hurts performance. 2286 2287 If unsure, say N: if you are compiling your own kernel, you 2288 are unlikely to be using a buggy version of glibc. 2289 2290choice 2291 prompt "vsyscall table for legacy applications" 2292 depends on X86_64 2293 default LEGACY_VSYSCALL_XONLY 2294 help 2295 Legacy user code that does not know how to find the vDSO expects 2296 to be able to issue three syscalls by calling fixed addresses in 2297 kernel space. Since this location is not randomized with ASLR, 2298 it can be used to assist security vulnerability exploitation. 2299 2300 This setting can be changed at boot time via the kernel command 2301 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2302 is deprecated and can only be enabled using the kernel command 2303 line. 2304 2305 On a system with recent enough glibc (2.14 or newer) and no 2306 static binaries, you can say None without a performance penalty 2307 to improve security. 2308 2309 If unsure, select "Emulate execution only". 2310 2311 config LEGACY_VSYSCALL_XONLY 2312 bool "Emulate execution only" 2313 help 2314 The kernel traps and emulates calls into the fixed vsyscall 2315 address mapping and does not allow reads. This 2316 configuration is recommended when userspace might use the 2317 legacy vsyscall area but support for legacy binary 2318 instrumentation of legacy code is not needed. It mitigates 2319 certain uses of the vsyscall area as an ASLR-bypassing 2320 buffer. 2321 2322 config LEGACY_VSYSCALL_NONE 2323 bool "None" 2324 help 2325 There will be no vsyscall mapping at all. This will 2326 eliminate any risk of ASLR bypass due to the vsyscall 2327 fixed address mapping. Attempts to use the vsyscalls 2328 will be reported to dmesg, so that either old or 2329 malicious userspace programs can be identified. 2330 2331endchoice 2332 2333config CMDLINE_BOOL 2334 bool "Built-in kernel command line" 2335 help 2336 Allow for specifying boot arguments to the kernel at 2337 build time. On some systems (e.g. embedded ones), it is 2338 necessary or convenient to provide some or all of the 2339 kernel boot arguments with the kernel itself (that is, 2340 to not rely on the boot loader to provide them.) 2341 2342 To compile command line arguments into the kernel, 2343 set this option to 'Y', then fill in the 2344 boot arguments in CONFIG_CMDLINE. 2345 2346 Systems with fully functional boot loaders (i.e. non-embedded) 2347 should leave this option set to 'N'. 2348 2349config CMDLINE 2350 string "Built-in kernel command string" 2351 depends on CMDLINE_BOOL 2352 default "" 2353 help 2354 Enter arguments here that should be compiled into the kernel 2355 image and used at boot time. If the boot loader provides a 2356 command line at boot time, it is appended to this string to 2357 form the full kernel command line, when the system boots. 2358 2359 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2360 change this behavior. 2361 2362 In most cases, the command line (whether built-in or provided 2363 by the boot loader) should specify the device for the root 2364 file system. 2365 2366config CMDLINE_OVERRIDE 2367 bool "Built-in command line overrides boot loader arguments" 2368 depends on CMDLINE_BOOL && CMDLINE != "" 2369 help 2370 Set this option to 'Y' to have the kernel ignore the boot loader 2371 command line, and use ONLY the built-in command line. 2372 2373 This is used to work around broken boot loaders. This should 2374 be set to 'N' under normal conditions. 2375 2376config MODIFY_LDT_SYSCALL 2377 bool "Enable the LDT (local descriptor table)" if EXPERT 2378 default y 2379 help 2380 Linux can allow user programs to install a per-process x86 2381 Local Descriptor Table (LDT) using the modify_ldt(2) system 2382 call. This is required to run 16-bit or segmented code such as 2383 DOSEMU or some Wine programs. It is also used by some very old 2384 threading libraries. 2385 2386 Enabling this feature adds a small amount of overhead to 2387 context switches and increases the low-level kernel attack 2388 surface. Disabling it removes the modify_ldt(2) system call. 2389 2390 Saying 'N' here may make sense for embedded or server kernels. 2391 2392config STRICT_SIGALTSTACK_SIZE 2393 bool "Enforce strict size checking for sigaltstack" 2394 depends on DYNAMIC_SIGFRAME 2395 help 2396 For historical reasons MINSIGSTKSZ is a constant which became 2397 already too small with AVX512 support. Add a mechanism to 2398 enforce strict checking of the sigaltstack size against the 2399 real size of the FPU frame. This option enables the check 2400 by default. It can also be controlled via the kernel command 2401 line option 'strict_sas_size' independent of this config 2402 switch. Enabling it might break existing applications which 2403 allocate a too small sigaltstack but 'work' because they 2404 never get a signal delivered. 2405 2406 Say 'N' unless you want to really enforce this check. 2407 2408config CFI_AUTO_DEFAULT 2409 bool "Attempt to use FineIBT by default at boot time" 2410 depends on FINEIBT 2411 default y 2412 help 2413 Attempt to use FineIBT by default at boot time. If enabled, 2414 this is the same as booting with "cfi=auto". If disabled, 2415 this is the same as booting with "cfi=kcfi". 2416 2417source "kernel/livepatch/Kconfig" 2418 2419endmenu 2420 2421config CC_HAS_NAMED_AS 2422 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null) 2423 depends on CC_IS_GCC 2424 2425config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2426 def_bool CC_IS_GCC && GCC_VERSION >= 130300 2427 2428config USE_X86_SEG_SUPPORT 2429 def_bool y 2430 depends on CC_HAS_NAMED_AS 2431 # 2432 # -fsanitize=kernel-address (KASAN) and -fsanitize=thread 2433 # (KCSAN) are incompatible with named address spaces with 2434 # GCC < 13.3 - see GCC PR sanitizer/111736. 2435 # 2436 depends on !(KASAN || KCSAN) || CC_HAS_NAMED_AS_FIXED_SANITIZERS 2437 2438config CC_HAS_SLS 2439 def_bool $(cc-option,-mharden-sls=all) 2440 2441config CC_HAS_RETURN_THUNK 2442 def_bool $(cc-option,-mfunction-return=thunk-extern) 2443 2444config CC_HAS_ENTRY_PADDING 2445 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2446 2447config FUNCTION_PADDING_CFI 2448 int 2449 default 59 if FUNCTION_ALIGNMENT_64B 2450 default 27 if FUNCTION_ALIGNMENT_32B 2451 default 11 if FUNCTION_ALIGNMENT_16B 2452 default 3 if FUNCTION_ALIGNMENT_8B 2453 default 0 2454 2455# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2456# except Kconfig can't do arithmetic :/ 2457config FUNCTION_PADDING_BYTES 2458 int 2459 default FUNCTION_PADDING_CFI if CFI_CLANG 2460 default FUNCTION_ALIGNMENT 2461 2462config CALL_PADDING 2463 def_bool n 2464 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2465 select FUNCTION_ALIGNMENT_16B 2466 2467config FINEIBT 2468 def_bool y 2469 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE 2470 select CALL_PADDING 2471 2472config HAVE_CALL_THUNKS 2473 def_bool y 2474 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2475 2476config CALL_THUNKS 2477 def_bool n 2478 select CALL_PADDING 2479 2480config PREFIX_SYMBOLS 2481 def_bool y 2482 depends on CALL_PADDING && !CFI_CLANG 2483 2484menuconfig CPU_MITIGATIONS 2485 bool "Mitigations for CPU vulnerabilities" 2486 default y 2487 help 2488 Say Y here to enable options which enable mitigations for hardware 2489 vulnerabilities (usually related to speculative execution). 2490 Mitigations can be disabled or restricted to SMT systems at runtime 2491 via the "mitigations" kernel parameter. 2492 2493 If you say N, all mitigations will be disabled. This CANNOT be 2494 overridden at runtime. 2495 2496 Say 'Y', unless you really know what you are doing. 2497 2498if CPU_MITIGATIONS 2499 2500config MITIGATION_PAGE_TABLE_ISOLATION 2501 bool "Remove the kernel mapping in user mode" 2502 default y 2503 depends on (X86_64 || X86_PAE) 2504 help 2505 This feature reduces the number of hardware side channels by 2506 ensuring that the majority of kernel addresses are not mapped 2507 into userspace. 2508 2509 See Documentation/arch/x86/pti.rst for more details. 2510 2511config MITIGATION_RETPOLINE 2512 bool "Avoid speculative indirect branches in kernel" 2513 select OBJTOOL if HAVE_OBJTOOL 2514 default y 2515 help 2516 Compile kernel with the retpoline compiler options to guard against 2517 kernel-to-user data leaks by avoiding speculative indirect 2518 branches. Requires a compiler with -mindirect-branch=thunk-extern 2519 support for full protection. The kernel may run slower. 2520 2521config MITIGATION_RETHUNK 2522 bool "Enable return-thunks" 2523 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2524 select OBJTOOL if HAVE_OBJTOOL 2525 default y if X86_64 2526 help 2527 Compile the kernel with the return-thunks compiler option to guard 2528 against kernel-to-user data leaks by avoiding return speculation. 2529 Requires a compiler with -mfunction-return=thunk-extern 2530 support for full protection. The kernel may run slower. 2531 2532config MITIGATION_UNRET_ENTRY 2533 bool "Enable UNRET on kernel entry" 2534 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2535 default y 2536 help 2537 Compile the kernel with support for the retbleed=unret mitigation. 2538 2539config MITIGATION_CALL_DEPTH_TRACKING 2540 bool "Mitigate RSB underflow with call depth tracking" 2541 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2542 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2543 select CALL_THUNKS 2544 default y 2545 help 2546 Compile the kernel with call depth tracking to mitigate the Intel 2547 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2548 mitigation is off by default and needs to be enabled on the 2549 kernel command line via the retbleed=stuff option. For 2550 non-affected systems the overhead of this option is marginal as 2551 the call depth tracking is using run-time generated call thunks 2552 in a compiler generated padding area and call patching. This 2553 increases text size by ~5%. For non affected systems this space 2554 is unused. On affected SKL systems this results in a significant 2555 performance gain over the IBRS mitigation. 2556 2557config CALL_THUNKS_DEBUG 2558 bool "Enable call thunks and call depth tracking debugging" 2559 depends on MITIGATION_CALL_DEPTH_TRACKING 2560 select FUNCTION_ALIGNMENT_32B 2561 default n 2562 help 2563 Enable call/ret counters for imbalance detection and build in 2564 a noisy dmesg about callthunks generation and call patching for 2565 trouble shooting. The debug prints need to be enabled on the 2566 kernel command line with 'debug-callthunks'. 2567 Only enable this when you are debugging call thunks as this 2568 creates a noticeable runtime overhead. If unsure say N. 2569 2570config MITIGATION_IBPB_ENTRY 2571 bool "Enable IBPB on kernel entry" 2572 depends on CPU_SUP_AMD && X86_64 2573 default y 2574 help 2575 Compile the kernel with support for the retbleed=ibpb mitigation. 2576 2577config MITIGATION_IBRS_ENTRY 2578 bool "Enable IBRS on kernel entry" 2579 depends on CPU_SUP_INTEL && X86_64 2580 default y 2581 help 2582 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2583 This mitigates both spectre_v2 and retbleed at great cost to 2584 performance. 2585 2586config MITIGATION_SRSO 2587 bool "Mitigate speculative RAS overflow on AMD" 2588 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2589 default y 2590 help 2591 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2592 2593config MITIGATION_SLS 2594 bool "Mitigate Straight-Line-Speculation" 2595 depends on CC_HAS_SLS && X86_64 2596 select OBJTOOL if HAVE_OBJTOOL 2597 default n 2598 help 2599 Compile the kernel with straight-line-speculation options to guard 2600 against straight line speculation. The kernel image might be slightly 2601 larger. 2602 2603config MITIGATION_GDS_FORCE 2604 bool "Force GDS Mitigation" 2605 depends on CPU_SUP_INTEL 2606 default n 2607 help 2608 Gather Data Sampling (GDS) is a hardware vulnerability which allows 2609 unprivileged speculative access to data which was previously stored in 2610 vector registers. 2611 2612 This option is equivalent to setting gather_data_sampling=force on the 2613 command line. The microcode mitigation is used if present, otherwise 2614 AVX is disabled as a mitigation. On affected systems that are missing 2615 the microcode any userspace code that unconditionally uses AVX will 2616 break with this option set. 2617 2618 Setting this option on systems not vulnerable to GDS has no effect. 2619 2620 If in doubt, say N. 2621 2622config MITIGATION_RFDS 2623 bool "RFDS Mitigation" 2624 depends on CPU_SUP_INTEL 2625 default y 2626 help 2627 Enable mitigation for Register File Data Sampling (RFDS) by default. 2628 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2629 allows unprivileged speculative access to stale data previously 2630 stored in floating point, vector and integer registers. 2631 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2632 2633config MITIGATION_SPECTRE_BHI 2634 bool "Mitigate Spectre-BHB (Branch History Injection)" 2635 depends on CPU_SUP_INTEL 2636 default y 2637 help 2638 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2639 where the branch history buffer is poisoned to speculatively steer 2640 indirect branches. 2641 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2642 2643endif 2644 2645config ARCH_HAS_ADD_PAGES 2646 def_bool y 2647 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2648 2649menu "Power management and ACPI options" 2650 2651config ARCH_HIBERNATION_HEADER 2652 def_bool y 2653 depends on HIBERNATION 2654 2655source "kernel/power/Kconfig" 2656 2657source "drivers/acpi/Kconfig" 2658 2659config X86_APM_BOOT 2660 def_bool y 2661 depends on APM 2662 2663menuconfig APM 2664 tristate "APM (Advanced Power Management) BIOS support" 2665 depends on X86_32 && PM_SLEEP 2666 help 2667 APM is a BIOS specification for saving power using several different 2668 techniques. This is mostly useful for battery powered laptops with 2669 APM compliant BIOSes. If you say Y here, the system time will be 2670 reset after a RESUME operation, the /proc/apm device will provide 2671 battery status information, and user-space programs will receive 2672 notification of APM "events" (e.g. battery status change). 2673 2674 If you select "Y" here, you can disable actual use of the APM 2675 BIOS by passing the "apm=off" option to the kernel at boot time. 2676 2677 Note that the APM support is almost completely disabled for 2678 machines with more than one CPU. 2679 2680 In order to use APM, you will need supporting software. For location 2681 and more information, read <file:Documentation/power/apm-acpi.rst> 2682 and the Battery Powered Linux mini-HOWTO, available from 2683 <http://www.tldp.org/docs.html#howto>. 2684 2685 This driver does not spin down disk drives (see the hdparm(8) 2686 manpage ("man 8 hdparm") for that), and it doesn't turn off 2687 VESA-compliant "green" monitors. 2688 2689 This driver does not support the TI 4000M TravelMate and the ACER 2690 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2691 desktop machines also don't have compliant BIOSes, and this driver 2692 may cause those machines to panic during the boot phase. 2693 2694 Generally, if you don't have a battery in your machine, there isn't 2695 much point in using this driver and you should say N. If you get 2696 random kernel OOPSes or reboots that don't seem to be related to 2697 anything, try disabling/enabling this option (or disabling/enabling 2698 APM in your BIOS). 2699 2700 Some other things you should try when experiencing seemingly random, 2701 "weird" problems: 2702 2703 1) make sure that you have enough swap space and that it is 2704 enabled. 2705 2) pass the "idle=poll" option to the kernel 2706 3) switch on floating point emulation in the kernel and pass 2707 the "no387" option to the kernel 2708 4) pass the "floppy=nodma" option to the kernel 2709 5) pass the "mem=4M" option to the kernel (thereby disabling 2710 all but the first 4 MB of RAM) 2711 6) make sure that the CPU is not over clocked. 2712 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2713 8) disable the cache from your BIOS settings 2714 9) install a fan for the video card or exchange video RAM 2715 10) install a better fan for the CPU 2716 11) exchange RAM chips 2717 12) exchange the motherboard. 2718 2719 To compile this driver as a module, choose M here: the 2720 module will be called apm. 2721 2722if APM 2723 2724config APM_IGNORE_USER_SUSPEND 2725 bool "Ignore USER SUSPEND" 2726 help 2727 This option will ignore USER SUSPEND requests. On machines with a 2728 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2729 series notebooks, it is necessary to say Y because of a BIOS bug. 2730 2731config APM_DO_ENABLE 2732 bool "Enable PM at boot time" 2733 help 2734 Enable APM features at boot time. From page 36 of the APM BIOS 2735 specification: "When disabled, the APM BIOS does not automatically 2736 power manage devices, enter the Standby State, enter the Suspend 2737 State, or take power saving steps in response to CPU Idle calls." 2738 This driver will make CPU Idle calls when Linux is idle (unless this 2739 feature is turned off -- see "Do CPU IDLE calls", below). This 2740 should always save battery power, but more complicated APM features 2741 will be dependent on your BIOS implementation. You may need to turn 2742 this option off if your computer hangs at boot time when using APM 2743 support, or if it beeps continuously instead of suspending. Turn 2744 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2745 T400CDT. This is off by default since most machines do fine without 2746 this feature. 2747 2748config APM_CPU_IDLE 2749 depends on CPU_IDLE 2750 bool "Make CPU Idle calls when idle" 2751 help 2752 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2753 On some machines, this can activate improved power savings, such as 2754 a slowed CPU clock rate, when the machine is idle. These idle calls 2755 are made after the idle loop has run for some length of time (e.g., 2756 333 mS). On some machines, this will cause a hang at boot time or 2757 whenever the CPU becomes idle. (On machines with more than one CPU, 2758 this option does nothing.) 2759 2760config APM_DISPLAY_BLANK 2761 bool "Enable console blanking using APM" 2762 help 2763 Enable console blanking using the APM. Some laptops can use this to 2764 turn off the LCD backlight when the screen blanker of the Linux 2765 virtual console blanks the screen. Note that this is only used by 2766 the virtual console screen blanker, and won't turn off the backlight 2767 when using the X Window system. This also doesn't have anything to 2768 do with your VESA-compliant power-saving monitor. Further, this 2769 option doesn't work for all laptops -- it might not turn off your 2770 backlight at all, or it might print a lot of errors to the console, 2771 especially if you are using gpm. 2772 2773config APM_ALLOW_INTS 2774 bool "Allow interrupts during APM BIOS calls" 2775 help 2776 Normally we disable external interrupts while we are making calls to 2777 the APM BIOS as a measure to lessen the effects of a badly behaving 2778 BIOS implementation. The BIOS should reenable interrupts if it 2779 needs to. Unfortunately, some BIOSes do not -- especially those in 2780 many of the newer IBM Thinkpads. If you experience hangs when you 2781 suspend, try setting this to Y. Otherwise, say N. 2782 2783endif # APM 2784 2785source "drivers/cpufreq/Kconfig" 2786 2787source "drivers/cpuidle/Kconfig" 2788 2789source "drivers/idle/Kconfig" 2790 2791endmenu 2792 2793menu "Bus options (PCI etc.)" 2794 2795choice 2796 prompt "PCI access mode" 2797 depends on X86_32 && PCI 2798 default PCI_GOANY 2799 help 2800 On PCI systems, the BIOS can be used to detect the PCI devices and 2801 determine their configuration. However, some old PCI motherboards 2802 have BIOS bugs and may crash if this is done. Also, some embedded 2803 PCI-based systems don't have any BIOS at all. Linux can also try to 2804 detect the PCI hardware directly without using the BIOS. 2805 2806 With this option, you can specify how Linux should detect the 2807 PCI devices. If you choose "BIOS", the BIOS will be used, 2808 if you choose "Direct", the BIOS won't be used, and if you 2809 choose "MMConfig", then PCI Express MMCONFIG will be used. 2810 If you choose "Any", the kernel will try MMCONFIG, then the 2811 direct access method and falls back to the BIOS if that doesn't 2812 work. If unsure, go with the default, which is "Any". 2813 2814config PCI_GOBIOS 2815 bool "BIOS" 2816 2817config PCI_GOMMCONFIG 2818 bool "MMConfig" 2819 2820config PCI_GODIRECT 2821 bool "Direct" 2822 2823config PCI_GOOLPC 2824 bool "OLPC XO-1" 2825 depends on OLPC 2826 2827config PCI_GOANY 2828 bool "Any" 2829 2830endchoice 2831 2832config PCI_BIOS 2833 def_bool y 2834 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2835 2836# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2837config PCI_DIRECT 2838 def_bool y 2839 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2840 2841config PCI_MMCONFIG 2842 bool "Support mmconfig PCI config space access" if X86_64 2843 default y 2844 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2845 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2846 2847config PCI_OLPC 2848 def_bool y 2849 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2850 2851config PCI_XEN 2852 def_bool y 2853 depends on PCI && XEN 2854 2855config MMCONF_FAM10H 2856 def_bool y 2857 depends on X86_64 && PCI_MMCONFIG && ACPI 2858 2859config PCI_CNB20LE_QUIRK 2860 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2861 depends on PCI 2862 help 2863 Read the PCI windows out of the CNB20LE host bridge. This allows 2864 PCI hotplug to work on systems with the CNB20LE chipset which do 2865 not have ACPI. 2866 2867 There's no public spec for this chipset, and this functionality 2868 is known to be incomplete. 2869 2870 You should say N unless you know you need this. 2871 2872config ISA_BUS 2873 bool "ISA bus support on modern systems" if EXPERT 2874 help 2875 Expose ISA bus device drivers and options available for selection and 2876 configuration. Enable this option if your target machine has an ISA 2877 bus. ISA is an older system, displaced by PCI and newer bus 2878 architectures -- if your target machine is modern, it probably does 2879 not have an ISA bus. 2880 2881 If unsure, say N. 2882 2883# x86_64 have no ISA slots, but can have ISA-style DMA. 2884config ISA_DMA_API 2885 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2886 default y 2887 help 2888 Enables ISA-style DMA support for devices requiring such controllers. 2889 If unsure, say Y. 2890 2891if X86_32 2892 2893config ISA 2894 bool "ISA support" 2895 help 2896 Find out whether you have ISA slots on your motherboard. ISA is the 2897 name of a bus system, i.e. the way the CPU talks to the other stuff 2898 inside your box. Other bus systems are PCI, EISA, MicroChannel 2899 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2900 newer boards don't support it. If you have ISA, say Y, otherwise N. 2901 2902config SCx200 2903 tristate "NatSemi SCx200 support" 2904 help 2905 This provides basic support for National Semiconductor's 2906 (now AMD's) Geode processors. The driver probes for the 2907 PCI-IDs of several on-chip devices, so its a good dependency 2908 for other scx200_* drivers. 2909 2910 If compiled as a module, the driver is named scx200. 2911 2912config SCx200HR_TIMER 2913 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2914 depends on SCx200 2915 default y 2916 help 2917 This driver provides a clocksource built upon the on-chip 2918 27MHz high-resolution timer. Its also a workaround for 2919 NSC Geode SC-1100's buggy TSC, which loses time when the 2920 processor goes idle (as is done by the scheduler). The 2921 other workaround is idle=poll boot option. 2922 2923config OLPC 2924 bool "One Laptop Per Child support" 2925 depends on !X86_PAE 2926 select GPIOLIB 2927 select OF 2928 select OF_PROMTREE 2929 select IRQ_DOMAIN 2930 select OLPC_EC 2931 help 2932 Add support for detecting the unique features of the OLPC 2933 XO hardware. 2934 2935config OLPC_XO1_PM 2936 bool "OLPC XO-1 Power Management" 2937 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2938 help 2939 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2940 2941config OLPC_XO1_RTC 2942 bool "OLPC XO-1 Real Time Clock" 2943 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2944 help 2945 Add support for the XO-1 real time clock, which can be used as a 2946 programmable wakeup source. 2947 2948config OLPC_XO1_SCI 2949 bool "OLPC XO-1 SCI extras" 2950 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2951 depends on INPUT=y 2952 select POWER_SUPPLY 2953 help 2954 Add support for SCI-based features of the OLPC XO-1 laptop: 2955 - EC-driven system wakeups 2956 - Power button 2957 - Ebook switch 2958 - Lid switch 2959 - AC adapter status updates 2960 - Battery status updates 2961 2962config OLPC_XO15_SCI 2963 bool "OLPC XO-1.5 SCI extras" 2964 depends on OLPC && ACPI 2965 select POWER_SUPPLY 2966 help 2967 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2968 - EC-driven system wakeups 2969 - AC adapter status updates 2970 - Battery status updates 2971 2972config ALIX 2973 bool "PCEngines ALIX System Support (LED setup)" 2974 select GPIOLIB 2975 help 2976 This option enables system support for the PCEngines ALIX. 2977 At present this just sets up LEDs for GPIO control on 2978 ALIX2/3/6 boards. However, other system specific setup should 2979 get added here. 2980 2981 Note: You must still enable the drivers for GPIO and LED support 2982 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2983 2984 Note: You have to set alix.force=1 for boards with Award BIOS. 2985 2986config NET5501 2987 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2988 select GPIOLIB 2989 help 2990 This option enables system support for the Soekris Engineering net5501. 2991 2992config GEOS 2993 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2994 select GPIOLIB 2995 depends on DMI 2996 help 2997 This option enables system support for the Traverse Technologies GEOS. 2998 2999config TS5500 3000 bool "Technologic Systems TS-5500 platform support" 3001 depends on MELAN 3002 select CHECK_SIGNATURE 3003 select NEW_LEDS 3004 select LEDS_CLASS 3005 help 3006 This option enables system support for the Technologic Systems TS-5500. 3007 3008endif # X86_32 3009 3010config AMD_NB 3011 def_bool y 3012 depends on CPU_SUP_AMD && PCI 3013 3014endmenu 3015 3016menu "Binary Emulations" 3017 3018config IA32_EMULATION 3019 bool "IA32 Emulation" 3020 depends on X86_64 3021 select ARCH_WANT_OLD_COMPAT_IPC 3022 select BINFMT_ELF 3023 select COMPAT_OLD_SIGACTION 3024 help 3025 Include code to run legacy 32-bit programs under a 3026 64-bit kernel. You should likely turn this on, unless you're 3027 100% sure that you don't have any 32-bit programs left. 3028 3029config IA32_EMULATION_DEFAULT_DISABLED 3030 bool "IA32 emulation disabled by default" 3031 default n 3032 depends on IA32_EMULATION 3033 help 3034 Make IA32 emulation disabled by default. This prevents loading 32-bit 3035 processes and access to 32-bit syscalls. If unsure, leave it to its 3036 default value. 3037 3038config X86_X32_ABI 3039 bool "x32 ABI for 64-bit mode" 3040 depends on X86_64 3041 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3042 # compressed debug sections to x86_x32 properly: 3043 # https://github.com/ClangBuiltLinux/linux/issues/514 3044 # https://github.com/ClangBuiltLinux/linux/issues/1141 3045 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3046 help 3047 Include code to run binaries for the x32 native 32-bit ABI 3048 for 64-bit processors. An x32 process gets access to the 3049 full 64-bit register file and wide data path while leaving 3050 pointers at 32 bits for smaller memory footprint. 3051 3052config COMPAT_32 3053 def_bool y 3054 depends on IA32_EMULATION || X86_32 3055 select HAVE_UID16 3056 select OLD_SIGSUSPEND3 3057 3058config COMPAT 3059 def_bool y 3060 depends on IA32_EMULATION || X86_X32_ABI 3061 3062config COMPAT_FOR_U64_ALIGNMENT 3063 def_bool y 3064 depends on COMPAT 3065 3066endmenu 3067 3068config HAVE_ATOMIC_IOMAP 3069 def_bool y 3070 depends on X86_32 3071 3072source "arch/x86/kvm/Kconfig" 3073 3074source "arch/x86/Kconfig.assembler" 3075