1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select HAVE_ARCH_SOFT_DIRTY 32 select MODULES_USE_ELF_RELA 33 select NEED_DMA_MAP_STATE 34 select SWIOTLB 35 select ARCH_HAS_ELFCORE_COMPAT 36 select ZONE_DMA32 37 select EXECMEM if DYNAMIC_FTRACE 38 39config FORCE_DYNAMIC_FTRACE 40 def_bool y 41 depends on X86_32 42 depends on FUNCTION_TRACER 43 select DYNAMIC_FTRACE 44 help 45 We keep the static function tracing (!DYNAMIC_FTRACE) around 46 in order to test the non static function tracing in the 47 generic code, as other architectures still use it. But we 48 only need to keep it around for x86_64. No need to keep it 49 for x86_32. For x86_32, force DYNAMIC_FTRACE. 50# 51# Arch settings 52# 53# ( Note that options that are marked 'if X86_64' could in principle be 54# ported to 32-bit as well. ) 55# 56config X86 57 def_bool y 58 # 59 # Note: keep this list sorted alphabetically 60 # 61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 63 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 64 select ARCH_32BIT_OFF_T if X86_32 65 select ARCH_CLOCKSOURCE_INIT 66 select ARCH_CONFIGURES_CPU_MITIGATIONS 67 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 68 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 69 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 70 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 71 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 72 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 73 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 74 select ARCH_HAS_CACHE_LINE_SIZE 75 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 76 select ARCH_HAS_CPU_FINALIZE_INIT 77 select ARCH_HAS_CPU_PASID if IOMMU_SVA 78 select ARCH_HAS_CURRENT_STACK_POINTER 79 select ARCH_HAS_DEBUG_VIRTUAL 80 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 81 select ARCH_HAS_DEVMEM_IS_ALLOWED 82 select ARCH_HAS_EARLY_DEBUG if KGDB 83 select ARCH_HAS_ELF_RANDOMIZE 84 select ARCH_HAS_FAST_MULTIPLIER 85 select ARCH_HAS_FORTIFY_SOURCE 86 select ARCH_HAS_GCOV_PROFILE_ALL 87 select ARCH_HAS_KCOV if X86_64 88 select ARCH_HAS_KERNEL_FPU_SUPPORT 89 select ARCH_HAS_MEM_ENCRYPT 90 select ARCH_HAS_MEMBARRIER_SYNC_CORE 91 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 92 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 93 select ARCH_HAS_PMEM_API if X86_64 94 select ARCH_HAS_PTE_DEVMAP if X86_64 95 select ARCH_HAS_PTE_SPECIAL 96 select ARCH_HAS_HW_PTE_YOUNG 97 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 98 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 99 select ARCH_HAS_COPY_MC if X86_64 100 select ARCH_HAS_SET_MEMORY 101 select ARCH_HAS_SET_DIRECT_MAP 102 select ARCH_HAS_STRICT_KERNEL_RWX 103 select ARCH_HAS_STRICT_MODULE_RWX 104 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 105 select ARCH_HAS_SYSCALL_WRAPPER 106 select ARCH_HAS_UBSAN 107 select ARCH_HAS_DEBUG_WX 108 select ARCH_HAS_ZONE_DMA_SET if EXPERT 109 select ARCH_HAVE_NMI_SAFE_CMPXCHG 110 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 111 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 112 select ARCH_MIGHT_HAVE_PC_PARPORT 113 select ARCH_MIGHT_HAVE_PC_SERIO 114 select ARCH_STACKWALK 115 select ARCH_SUPPORTS_ACPI 116 select ARCH_SUPPORTS_ATOMIC_RMW 117 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 118 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 119 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 120 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 121 select ARCH_SUPPORTS_CFI_CLANG if X86_64 122 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 123 select ARCH_SUPPORTS_LTO_CLANG 124 select ARCH_SUPPORTS_LTO_CLANG_THIN 125 select ARCH_USE_BUILTIN_BSWAP 126 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64 127 select ARCH_USE_MEMTEST 128 select ARCH_USE_QUEUED_RWLOCKS 129 select ARCH_USE_QUEUED_SPINLOCKS 130 select ARCH_USE_SYM_ANNOTATIONS 131 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 132 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 133 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 134 select ARCH_WANTS_NO_INSTR 135 select ARCH_WANT_GENERAL_HUGETLB 136 select ARCH_WANT_HUGE_PMD_SHARE 137 select ARCH_WANT_LD_ORPHAN_WARN 138 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 139 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 140 select ARCH_WANTS_THP_SWAP if X86_64 141 select ARCH_HAS_PARANOID_L1D_FLUSH 142 select BUILDTIME_TABLE_SORT 143 select CLKEVT_I8253 144 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 145 select CLOCKSOURCE_WATCHDOG 146 # Word-size accesses may read uninitialized data past the trailing \0 147 # in strings and cause false KMSAN reports. 148 select DCACHE_WORD_ACCESS if !KMSAN 149 select DYNAMIC_SIGFRAME 150 select EDAC_ATOMIC_SCRUB 151 select EDAC_SUPPORT 152 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 153 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 154 select GENERIC_CLOCKEVENTS_MIN_ADJUST 155 select GENERIC_CMOS_UPDATE 156 select GENERIC_CPU_AUTOPROBE 157 select GENERIC_CPU_DEVICES 158 select GENERIC_CPU_VULNERABILITIES 159 select GENERIC_EARLY_IOREMAP 160 select GENERIC_ENTRY 161 select GENERIC_IOMAP 162 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 163 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 164 select GENERIC_IRQ_MIGRATION if SMP 165 select GENERIC_IRQ_PROBE 166 select GENERIC_IRQ_RESERVATION_MODE 167 select GENERIC_IRQ_SHOW 168 select GENERIC_PENDING_IRQ if SMP 169 select GENERIC_PTDUMP 170 select GENERIC_SMP_IDLE_THREAD 171 select GENERIC_TIME_VSYSCALL 172 select GENERIC_GETTIMEOFDAY 173 select GENERIC_VDSO_TIME_NS 174 select GENERIC_VDSO_OVERFLOW_PROTECT 175 select GUP_GET_PXX_LOW_HIGH if X86_PAE 176 select HARDIRQS_SW_RESEND 177 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 178 select HAS_IOPORT 179 select HAVE_ACPI_APEI if ACPI 180 select HAVE_ACPI_APEI_NMI if ACPI 181 select HAVE_ALIGNED_STRUCT_PAGE 182 select HAVE_ARCH_AUDITSYSCALL 183 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 184 select HAVE_ARCH_HUGE_VMALLOC if X86_64 185 select HAVE_ARCH_JUMP_LABEL 186 select HAVE_ARCH_JUMP_LABEL_RELATIVE 187 select HAVE_ARCH_KASAN if X86_64 188 select HAVE_ARCH_KASAN_VMALLOC if X86_64 189 select HAVE_ARCH_KFENCE 190 select HAVE_ARCH_KMSAN if X86_64 191 select HAVE_ARCH_KGDB 192 select HAVE_ARCH_MMAP_RND_BITS if MMU 193 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 194 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 195 select HAVE_ARCH_PREL32_RELOCATIONS 196 select HAVE_ARCH_SECCOMP_FILTER 197 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 198 select HAVE_ARCH_STACKLEAK 199 select HAVE_ARCH_TRACEHOOK 200 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 201 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 202 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 203 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 204 select HAVE_ARCH_VMAP_STACK if X86_64 205 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 206 select HAVE_ARCH_WITHIN_STACK_FRAMES 207 select HAVE_ASM_MODVERSIONS 208 select HAVE_CMPXCHG_DOUBLE 209 select HAVE_CMPXCHG_LOCAL 210 select HAVE_CONTEXT_TRACKING_USER if X86_64 211 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 212 select HAVE_C_RECORDMCOUNT 213 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 214 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 215 select HAVE_BUILDTIME_MCOUNT_SORT 216 select HAVE_DEBUG_KMEMLEAK 217 select HAVE_DMA_CONTIGUOUS 218 select HAVE_DYNAMIC_FTRACE 219 select HAVE_DYNAMIC_FTRACE_WITH_REGS 220 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 221 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 222 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 223 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 224 select HAVE_EBPF_JIT 225 select HAVE_EFFICIENT_UNALIGNED_ACCESS 226 select HAVE_EISA 227 select HAVE_EXIT_THREAD 228 select HAVE_GUP_FAST 229 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 230 select HAVE_FTRACE_MCOUNT_RECORD 231 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 232 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 233 select HAVE_FUNCTION_TRACER 234 select HAVE_GCC_PLUGINS 235 select HAVE_HW_BREAKPOINT 236 select HAVE_IOREMAP_PROT 237 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 238 select HAVE_IRQ_TIME_ACCOUNTING 239 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 240 select HAVE_KERNEL_BZIP2 241 select HAVE_KERNEL_GZIP 242 select HAVE_KERNEL_LZ4 243 select HAVE_KERNEL_LZMA 244 select HAVE_KERNEL_LZO 245 select HAVE_KERNEL_XZ 246 select HAVE_KERNEL_ZSTD 247 select HAVE_KPROBES 248 select HAVE_KPROBES_ON_FTRACE 249 select HAVE_FUNCTION_ERROR_INJECTION 250 select HAVE_KRETPROBES 251 select HAVE_RETHOOK 252 select HAVE_LIVEPATCH if X86_64 253 select HAVE_MIXED_BREAKPOINTS_REGS 254 select HAVE_MOD_ARCH_SPECIFIC 255 select HAVE_MOVE_PMD 256 select HAVE_MOVE_PUD 257 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 258 select HAVE_NMI 259 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 260 select HAVE_OBJTOOL if X86_64 261 select HAVE_OPTPROBES 262 select HAVE_PAGE_SIZE_4KB 263 select HAVE_PCSPKR_PLATFORM 264 select HAVE_PERF_EVENTS 265 select HAVE_PERF_EVENTS_NMI 266 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 267 select HAVE_PCI 268 select HAVE_PERF_REGS 269 select HAVE_PERF_USER_STACK_DUMP 270 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 271 select MMU_GATHER_MERGE_VMAS 272 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 273 select HAVE_REGS_AND_STACK_ACCESS_API 274 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 275 select HAVE_FUNCTION_ARG_ACCESS_API 276 select HAVE_SETUP_PER_CPU_AREA 277 select HAVE_SOFTIRQ_ON_OWN_STACK 278 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 279 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 280 select HAVE_STATIC_CALL 281 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 282 select HAVE_PREEMPT_DYNAMIC_CALL 283 select HAVE_RSEQ 284 select HAVE_RUST if X86_64 285 select HAVE_SYSCALL_TRACEPOINTS 286 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 287 select HAVE_UNSTABLE_SCHED_CLOCK 288 select HAVE_USER_RETURN_NOTIFIER 289 select HAVE_GENERIC_VDSO 290 select HOTPLUG_PARALLEL if SMP && X86_64 291 select HOTPLUG_SMT if SMP 292 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 293 select IRQ_FORCED_THREADING 294 select LOCK_MM_AND_FIND_VMA 295 select NEED_PER_CPU_EMBED_FIRST_CHUNK 296 select NEED_PER_CPU_PAGE_FIRST_CHUNK 297 select NEED_SG_DMA_LENGTH 298 select PCI_DOMAINS if PCI 299 select PCI_LOCKLESS_CONFIG if PCI 300 select PERF_EVENTS 301 select RTC_LIB 302 select RTC_MC146818_LIB 303 select SPARSE_IRQ 304 select SYSCTL_EXCEPTION_TRACE 305 select THREAD_INFO_IN_TASK 306 select TRACE_IRQFLAGS_SUPPORT 307 select TRACE_IRQFLAGS_NMI_SUPPORT 308 select USER_STACKTRACE_SUPPORT 309 select HAVE_ARCH_KCSAN if X86_64 310 select PROC_PID_ARCH_STATUS if PROC_FS 311 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 312 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 313 select FUNCTION_ALIGNMENT_4B 314 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 315 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 316 317config INSTRUCTION_DECODER 318 def_bool y 319 depends on KPROBES || PERF_EVENTS || UPROBES 320 321config OUTPUT_FORMAT 322 string 323 default "elf32-i386" if X86_32 324 default "elf64-x86-64" if X86_64 325 326config LOCKDEP_SUPPORT 327 def_bool y 328 329config STACKTRACE_SUPPORT 330 def_bool y 331 332config MMU 333 def_bool y 334 335config ARCH_MMAP_RND_BITS_MIN 336 default 28 if 64BIT 337 default 8 338 339config ARCH_MMAP_RND_BITS_MAX 340 default 32 if 64BIT 341 default 16 342 343config ARCH_MMAP_RND_COMPAT_BITS_MIN 344 default 8 345 346config ARCH_MMAP_RND_COMPAT_BITS_MAX 347 default 16 348 349config SBUS 350 bool 351 352config GENERIC_ISA_DMA 353 def_bool y 354 depends on ISA_DMA_API 355 356config GENERIC_CSUM 357 bool 358 default y if KMSAN || KASAN 359 360config GENERIC_BUG 361 def_bool y 362 depends on BUG 363 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 364 365config GENERIC_BUG_RELATIVE_POINTERS 366 bool 367 368config ARCH_MAY_HAVE_PC_FDC 369 def_bool y 370 depends on ISA_DMA_API 371 372config GENERIC_CALIBRATE_DELAY 373 def_bool y 374 375config ARCH_HAS_CPU_RELAX 376 def_bool y 377 378config ARCH_HIBERNATION_POSSIBLE 379 def_bool y 380 381config ARCH_SUSPEND_POSSIBLE 382 def_bool y 383 384config AUDIT_ARCH 385 def_bool y if X86_64 386 387config KASAN_SHADOW_OFFSET 388 hex 389 depends on KASAN 390 default 0xdffffc0000000000 391 392config HAVE_INTEL_TXT 393 def_bool y 394 depends on INTEL_IOMMU && ACPI 395 396config X86_64_SMP 397 def_bool y 398 depends on X86_64 && SMP 399 400config ARCH_SUPPORTS_UPROBES 401 def_bool y 402 403config FIX_EARLYCON_MEM 404 def_bool y 405 406config DYNAMIC_PHYSICAL_MASK 407 bool 408 409config PGTABLE_LEVELS 410 int 411 default 5 if X86_5LEVEL 412 default 4 if X86_64 413 default 3 if X86_PAE 414 default 2 415 416config CC_HAS_SANE_STACKPROTECTOR 417 bool 418 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 419 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 420 help 421 We have to make sure stack protector is unconditionally disabled if 422 the compiler produces broken code or if it does not let us control 423 the segment on 32-bit kernels. 424 425menu "Processor type and features" 426 427config SMP 428 bool "Symmetric multi-processing support" 429 help 430 This enables support for systems with more than one CPU. If you have 431 a system with only one CPU, say N. If you have a system with more 432 than one CPU, say Y. 433 434 If you say N here, the kernel will run on uni- and multiprocessor 435 machines, but will use only one CPU of a multiprocessor machine. If 436 you say Y here, the kernel will run on many, but not all, 437 uniprocessor machines. On a uniprocessor machine, the kernel 438 will run faster if you say N here. 439 440 Note that if you say Y here and choose architecture "586" or 441 "Pentium" under "Processor family", the kernel will not work on 486 442 architectures. Similarly, multiprocessor kernels for the "PPro" 443 architecture may not work on all Pentium based boards. 444 445 People using multiprocessor machines who say Y here should also say 446 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 447 Management" code will be disabled if you say Y here. 448 449 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 450 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 451 <http://www.tldp.org/docs.html#howto>. 452 453 If you don't know what to do here, say N. 454 455config X86_X2APIC 456 bool "Support x2apic" 457 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 458 help 459 This enables x2apic support on CPUs that have this feature. 460 461 This allows 32-bit apic IDs (so it can support very large systems), 462 and accesses the local apic via MSRs not via mmio. 463 464 Some Intel systems circa 2022 and later are locked into x2APIC mode 465 and can not fall back to the legacy APIC modes if SGX or TDX are 466 enabled in the BIOS. They will boot with very reduced functionality 467 without enabling this option. 468 469 If you don't know what to do here, say N. 470 471config X86_POSTED_MSI 472 bool "Enable MSI and MSI-x delivery by posted interrupts" 473 depends on X86_64 && IRQ_REMAP 474 help 475 This enables MSIs that are under interrupt remapping to be delivered as 476 posted interrupts to the host kernel. Interrupt throughput can 477 potentially be improved by coalescing CPU notifications during high 478 frequency bursts. 479 480 If you don't know what to do here, say N. 481 482config X86_MPPARSE 483 bool "Enable MPS table" if ACPI 484 default y 485 depends on X86_LOCAL_APIC 486 help 487 For old smp systems that do not have proper acpi support. Newer systems 488 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 489 490config X86_CPU_RESCTRL 491 bool "x86 CPU resource control support" 492 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 493 select KERNFS 494 select PROC_CPU_RESCTRL if PROC_FS 495 help 496 Enable x86 CPU resource control support. 497 498 Provide support for the allocation and monitoring of system resources 499 usage by the CPU. 500 501 Intel calls this Intel Resource Director Technology 502 (Intel(R) RDT). More information about RDT can be found in the 503 Intel x86 Architecture Software Developer Manual. 504 505 AMD calls this AMD Platform Quality of Service (AMD QoS). 506 More information about AMD QoS can be found in the AMD64 Technology 507 Platform Quality of Service Extensions manual. 508 509 Say N if unsure. 510 511config X86_FRED 512 bool "Flexible Return and Event Delivery" 513 depends on X86_64 514 help 515 When enabled, try to use Flexible Return and Event Delivery 516 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 517 ring transitions and exception/interrupt handling if the 518 system supports it. 519 520config X86_BIGSMP 521 bool "Support for big SMP systems with more than 8 CPUs" 522 depends on SMP && X86_32 523 help 524 This option is needed for the systems that have more than 8 CPUs. 525 526config X86_EXTENDED_PLATFORM 527 bool "Support for extended (non-PC) x86 platforms" 528 default y 529 help 530 If you disable this option then the kernel will only support 531 standard PC platforms. (which covers the vast majority of 532 systems out there.) 533 534 If you enable this option then you'll be able to select support 535 for the following non-PC x86 platforms, depending on the value of 536 CONFIG_64BIT. 537 538 32-bit platforms (CONFIG_64BIT=n): 539 Goldfish (Android emulator) 540 AMD Elan 541 RDC R-321x SoC 542 SGI 320/540 (Visual Workstation) 543 STA2X11-based (e.g. Northville) 544 Moorestown MID devices 545 546 64-bit platforms (CONFIG_64BIT=y): 547 Numascale NumaChip 548 ScaleMP vSMP 549 SGI Ultraviolet 550 551 If you have one of these systems, or if you want to build a 552 generic distribution kernel, say Y here - otherwise say N. 553 554# This is an alphabetically sorted list of 64 bit extended platforms 555# Please maintain the alphabetic order if and when there are additions 556config X86_NUMACHIP 557 bool "Numascale NumaChip" 558 depends on X86_64 559 depends on X86_EXTENDED_PLATFORM 560 depends on NUMA 561 depends on SMP 562 depends on X86_X2APIC 563 depends on PCI_MMCONFIG 564 help 565 Adds support for Numascale NumaChip large-SMP systems. Needed to 566 enable more than ~168 cores. 567 If you don't have one of these, you should say N here. 568 569config X86_VSMP 570 bool "ScaleMP vSMP" 571 select HYPERVISOR_GUEST 572 select PARAVIRT 573 depends on X86_64 && PCI 574 depends on X86_EXTENDED_PLATFORM 575 depends on SMP 576 help 577 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 578 supposed to run on these EM64T-based machines. Only choose this option 579 if you have one of these machines. 580 581config X86_UV 582 bool "SGI Ultraviolet" 583 depends on X86_64 584 depends on X86_EXTENDED_PLATFORM 585 depends on NUMA 586 depends on EFI 587 depends on KEXEC_CORE 588 depends on X86_X2APIC 589 depends on PCI 590 help 591 This option is needed in order to support SGI Ultraviolet systems. 592 If you don't have one of these, you should say N here. 593 594# Following is an alphabetically sorted list of 32 bit extended platforms 595# Please maintain the alphabetic order if and when there are additions 596 597config X86_GOLDFISH 598 bool "Goldfish (Virtual Platform)" 599 depends on X86_EXTENDED_PLATFORM 600 help 601 Enable support for the Goldfish virtual platform used primarily 602 for Android development. Unless you are building for the Android 603 Goldfish emulator say N here. 604 605config X86_INTEL_CE 606 bool "CE4100 TV platform" 607 depends on PCI 608 depends on PCI_GODIRECT 609 depends on X86_IO_APIC 610 depends on X86_32 611 depends on X86_EXTENDED_PLATFORM 612 select X86_REBOOTFIXUPS 613 select OF 614 select OF_EARLY_FLATTREE 615 help 616 Select for the Intel CE media processor (CE4100) SOC. 617 This option compiles in support for the CE4100 SOC for settop 618 boxes and media devices. 619 620config X86_INTEL_MID 621 bool "Intel MID platform support" 622 depends on X86_EXTENDED_PLATFORM 623 depends on X86_PLATFORM_DEVICES 624 depends on PCI 625 depends on X86_64 || (PCI_GOANY && X86_32) 626 depends on X86_IO_APIC 627 select I2C 628 select DW_APB_TIMER 629 select INTEL_SCU_PCI 630 help 631 Select to build a kernel capable of supporting Intel MID (Mobile 632 Internet Device) platform systems which do not have the PCI legacy 633 interfaces. If you are building for a PC class system say N here. 634 635 Intel MID platforms are based on an Intel processor and chipset which 636 consume less power than most of the x86 derivatives. 637 638config X86_INTEL_QUARK 639 bool "Intel Quark platform support" 640 depends on X86_32 641 depends on X86_EXTENDED_PLATFORM 642 depends on X86_PLATFORM_DEVICES 643 depends on X86_TSC 644 depends on PCI 645 depends on PCI_GOANY 646 depends on X86_IO_APIC 647 select IOSF_MBI 648 select INTEL_IMR 649 select COMMON_CLK 650 help 651 Select to include support for Quark X1000 SoC. 652 Say Y here if you have a Quark based system such as the Arduino 653 compatible Intel Galileo. 654 655config X86_INTEL_LPSS 656 bool "Intel Low Power Subsystem Support" 657 depends on X86 && ACPI && PCI 658 select COMMON_CLK 659 select PINCTRL 660 select IOSF_MBI 661 help 662 Select to build support for Intel Low Power Subsystem such as 663 found on Intel Lynxpoint PCH. Selecting this option enables 664 things like clock tree (common clock framework) and pincontrol 665 which are needed by the LPSS peripheral drivers. 666 667config X86_AMD_PLATFORM_DEVICE 668 bool "AMD ACPI2Platform devices support" 669 depends on ACPI 670 select COMMON_CLK 671 select PINCTRL 672 help 673 Select to interpret AMD specific ACPI device to platform device 674 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 675 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 676 implemented under PINCTRL subsystem. 677 678config IOSF_MBI 679 tristate "Intel SoC IOSF Sideband support for SoC platforms" 680 depends on PCI 681 help 682 This option enables sideband register access support for Intel SoC 683 platforms. On these platforms the IOSF sideband is used in lieu of 684 MSR's for some register accesses, mostly but not limited to thermal 685 and power. Drivers may query the availability of this device to 686 determine if they need the sideband in order to work on these 687 platforms. The sideband is available on the following SoC products. 688 This list is not meant to be exclusive. 689 - BayTrail 690 - Braswell 691 - Quark 692 693 You should say Y if you are running a kernel on one of these SoC's. 694 695config IOSF_MBI_DEBUG 696 bool "Enable IOSF sideband access through debugfs" 697 depends on IOSF_MBI && DEBUG_FS 698 help 699 Select this option to expose the IOSF sideband access registers (MCR, 700 MDR, MCRX) through debugfs to write and read register information from 701 different units on the SoC. This is most useful for obtaining device 702 state information for debug and analysis. As this is a general access 703 mechanism, users of this option would have specific knowledge of the 704 device they want to access. 705 706 If you don't require the option or are in doubt, say N. 707 708config X86_RDC321X 709 bool "RDC R-321x SoC" 710 depends on X86_32 711 depends on X86_EXTENDED_PLATFORM 712 select M486 713 select X86_REBOOTFIXUPS 714 help 715 This option is needed for RDC R-321x system-on-chip, also known 716 as R-8610-(G). 717 If you don't have one of these chips, you should say N here. 718 719config X86_32_NON_STANDARD 720 bool "Support non-standard 32-bit SMP architectures" 721 depends on X86_32 && SMP 722 depends on X86_EXTENDED_PLATFORM 723 help 724 This option compiles in the bigsmp and STA2X11 default 725 subarchitectures. It is intended for a generic binary 726 kernel. If you select them all, kernel will probe it one by 727 one and will fallback to default. 728 729# Alphabetically sorted list of Non standard 32 bit platforms 730 731config X86_SUPPORTS_MEMORY_FAILURE 732 def_bool y 733 # MCE code calls memory_failure(): 734 depends on X86_MCE 735 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 736 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 737 depends on X86_64 || !SPARSEMEM 738 select ARCH_SUPPORTS_MEMORY_FAILURE 739 740config STA2X11 741 bool "STA2X11 Companion Chip Support" 742 depends on X86_32_NON_STANDARD && PCI 743 select SWIOTLB 744 select MFD_STA2X11 745 select GPIOLIB 746 help 747 This adds support for boards based on the STA2X11 IO-Hub, 748 a.k.a. "ConneXt". The chip is used in place of the standard 749 PC chipset, so all "standard" peripherals are missing. If this 750 option is selected the kernel will still be able to boot on 751 standard PC machines. 752 753config X86_32_IRIS 754 tristate "Eurobraille/Iris poweroff module" 755 depends on X86_32 756 help 757 The Iris machines from EuroBraille do not have APM or ACPI support 758 to shut themselves down properly. A special I/O sequence is 759 needed to do so, which is what this module does at 760 kernel shutdown. 761 762 This is only for Iris machines from EuroBraille. 763 764 If unused, say N. 765 766config SCHED_OMIT_FRAME_POINTER 767 def_bool y 768 prompt "Single-depth WCHAN output" 769 depends on X86 770 help 771 Calculate simpler /proc/<PID>/wchan values. If this option 772 is disabled then wchan values will recurse back to the 773 caller function. This provides more accurate wchan values, 774 at the expense of slightly more scheduling overhead. 775 776 If in doubt, say "Y". 777 778menuconfig HYPERVISOR_GUEST 779 bool "Linux guest support" 780 help 781 Say Y here to enable options for running Linux under various hyper- 782 visors. This option enables basic hypervisor detection and platform 783 setup. 784 785 If you say N, all options in this submenu will be skipped and 786 disabled, and Linux guest support won't be built in. 787 788if HYPERVISOR_GUEST 789 790config PARAVIRT 791 bool "Enable paravirtualization code" 792 depends on HAVE_STATIC_CALL 793 help 794 This changes the kernel so it can modify itself when it is run 795 under a hypervisor, potentially improving performance significantly 796 over full virtualization. However, when run without a hypervisor 797 the kernel is theoretically slower and slightly larger. 798 799config PARAVIRT_XXL 800 bool 801 802config PARAVIRT_DEBUG 803 bool "paravirt-ops debugging" 804 depends on PARAVIRT && DEBUG_KERNEL 805 help 806 Enable to debug paravirt_ops internals. Specifically, BUG if 807 a paravirt_op is missing when it is called. 808 809config PARAVIRT_SPINLOCKS 810 bool "Paravirtualization layer for spinlocks" 811 depends on PARAVIRT && SMP 812 help 813 Paravirtualized spinlocks allow a pvops backend to replace the 814 spinlock implementation with something virtualization-friendly 815 (for example, block the virtual CPU rather than spinning). 816 817 It has a minimal impact on native kernels and gives a nice performance 818 benefit on paravirtualized KVM / Xen kernels. 819 820 If you are unsure how to answer this question, answer Y. 821 822config X86_HV_CALLBACK_VECTOR 823 def_bool n 824 825source "arch/x86/xen/Kconfig" 826 827config KVM_GUEST 828 bool "KVM Guest support (including kvmclock)" 829 depends on PARAVIRT 830 select PARAVIRT_CLOCK 831 select ARCH_CPUIDLE_HALTPOLL 832 select X86_HV_CALLBACK_VECTOR 833 default y 834 help 835 This option enables various optimizations for running under the KVM 836 hypervisor. It includes a paravirtualized clock, so that instead 837 of relying on a PIT (or probably other) emulation by the 838 underlying device model, the host provides the guest with 839 timing infrastructure such as time of day, and system time 840 841config ARCH_CPUIDLE_HALTPOLL 842 def_bool n 843 prompt "Disable host haltpoll when loading haltpoll driver" 844 help 845 If virtualized under KVM, disable host haltpoll. 846 847config PVH 848 bool "Support for running PVH guests" 849 help 850 This option enables the PVH entry point for guest virtual machines 851 as specified in the x86/HVM direct boot ABI. 852 853config PARAVIRT_TIME_ACCOUNTING 854 bool "Paravirtual steal time accounting" 855 depends on PARAVIRT 856 help 857 Select this option to enable fine granularity task steal time 858 accounting. Time spent executing other tasks in parallel with 859 the current vCPU is discounted from the vCPU power. To account for 860 that, there can be a small performance impact. 861 862 If in doubt, say N here. 863 864config PARAVIRT_CLOCK 865 bool 866 867config JAILHOUSE_GUEST 868 bool "Jailhouse non-root cell support" 869 depends on X86_64 && PCI 870 select X86_PM_TIMER 871 help 872 This option allows to run Linux as guest in a Jailhouse non-root 873 cell. You can leave this option disabled if you only want to start 874 Jailhouse and run Linux afterwards in the root cell. 875 876config ACRN_GUEST 877 bool "ACRN Guest support" 878 depends on X86_64 879 select X86_HV_CALLBACK_VECTOR 880 help 881 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 882 a flexible, lightweight reference open-source hypervisor, built with 883 real-time and safety-criticality in mind. It is built for embedded 884 IOT with small footprint and real-time features. More details can be 885 found in https://projectacrn.org/. 886 887config INTEL_TDX_GUEST 888 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 889 depends on X86_64 && CPU_SUP_INTEL 890 depends on X86_X2APIC 891 depends on EFI_STUB 892 select ARCH_HAS_CC_PLATFORM 893 select X86_MEM_ENCRYPT 894 select X86_MCE 895 select UNACCEPTED_MEMORY 896 help 897 Support running as a guest under Intel TDX. Without this support, 898 the guest kernel can not boot or run under TDX. 899 TDX includes memory encryption and integrity capabilities 900 which protect the confidentiality and integrity of guest 901 memory contents and CPU state. TDX guests are protected from 902 some attacks from the VMM. 903 904endif # HYPERVISOR_GUEST 905 906source "arch/x86/Kconfig.cpu" 907 908config HPET_TIMER 909 def_bool X86_64 910 prompt "HPET Timer Support" if X86_32 911 help 912 Use the IA-PC HPET (High Precision Event Timer) to manage 913 time in preference to the PIT and RTC, if a HPET is 914 present. 915 HPET is the next generation timer replacing legacy 8254s. 916 The HPET provides a stable time base on SMP 917 systems, unlike the TSC, but it is more expensive to access, 918 as it is off-chip. The interface used is documented 919 in the HPET spec, revision 1. 920 921 You can safely choose Y here. However, HPET will only be 922 activated if the platform and the BIOS support this feature. 923 Otherwise the 8254 will be used for timing services. 924 925 Choose N to continue using the legacy 8254 timer. 926 927config HPET_EMULATE_RTC 928 def_bool y 929 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 930 931# Mark as expert because too many people got it wrong. 932# The code disables itself when not needed. 933config DMI 934 default y 935 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 936 bool "Enable DMI scanning" if EXPERT 937 help 938 Enabled scanning of DMI to identify machine quirks. Say Y 939 here unless you have verified that your setup is not 940 affected by entries in the DMI blacklist. Required by PNP 941 BIOS code. 942 943config GART_IOMMU 944 bool "Old AMD GART IOMMU support" 945 select DMA_OPS 946 select IOMMU_HELPER 947 select SWIOTLB 948 depends on X86_64 && PCI && AMD_NB 949 help 950 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 951 GART based hardware IOMMUs. 952 953 The GART supports full DMA access for devices with 32-bit access 954 limitations, on systems with more than 3 GB. This is usually needed 955 for USB, sound, many IDE/SATA chipsets and some other devices. 956 957 Newer systems typically have a modern AMD IOMMU, supported via 958 the CONFIG_AMD_IOMMU=y config option. 959 960 In normal configurations this driver is only active when needed: 961 there's more than 3 GB of memory and the system contains a 962 32-bit limited device. 963 964 If unsure, say Y. 965 966config BOOT_VESA_SUPPORT 967 bool 968 help 969 If true, at least one selected framebuffer driver can take advantage 970 of VESA video modes set at an early boot stage via the vga= parameter. 971 972config MAXSMP 973 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 974 depends on X86_64 && SMP && DEBUG_KERNEL 975 select CPUMASK_OFFSTACK 976 help 977 Enable maximum number of CPUS and NUMA Nodes for this architecture. 978 If unsure, say N. 979 980# 981# The maximum number of CPUs supported: 982# 983# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 984# and which can be configured interactively in the 985# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 986# 987# The ranges are different on 32-bit and 64-bit kernels, depending on 988# hardware capabilities and scalability features of the kernel. 989# 990# ( If MAXSMP is enabled we just use the highest possible value and disable 991# interactive configuration. ) 992# 993 994config NR_CPUS_RANGE_BEGIN 995 int 996 default NR_CPUS_RANGE_END if MAXSMP 997 default 1 if !SMP 998 default 2 999 1000config NR_CPUS_RANGE_END 1001 int 1002 depends on X86_32 1003 default 64 if SMP && X86_BIGSMP 1004 default 8 if SMP && !X86_BIGSMP 1005 default 1 if !SMP 1006 1007config NR_CPUS_RANGE_END 1008 int 1009 depends on X86_64 1010 default 8192 if SMP && CPUMASK_OFFSTACK 1011 default 512 if SMP && !CPUMASK_OFFSTACK 1012 default 1 if !SMP 1013 1014config NR_CPUS_DEFAULT 1015 int 1016 depends on X86_32 1017 default 32 if X86_BIGSMP 1018 default 8 if SMP 1019 default 1 if !SMP 1020 1021config NR_CPUS_DEFAULT 1022 int 1023 depends on X86_64 1024 default 8192 if MAXSMP 1025 default 64 if SMP 1026 default 1 if !SMP 1027 1028config NR_CPUS 1029 int "Maximum number of CPUs" if SMP && !MAXSMP 1030 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1031 default NR_CPUS_DEFAULT 1032 help 1033 This allows you to specify the maximum number of CPUs which this 1034 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1035 supported value is 8192, otherwise the maximum value is 512. The 1036 minimum value which makes sense is 2. 1037 1038 This is purely to save memory: each supported CPU adds about 8KB 1039 to the kernel image. 1040 1041config SCHED_CLUSTER 1042 bool "Cluster scheduler support" 1043 depends on SMP 1044 default y 1045 help 1046 Cluster scheduler support improves the CPU scheduler's decision 1047 making when dealing with machines that have clusters of CPUs. 1048 Cluster usually means a couple of CPUs which are placed closely 1049 by sharing mid-level caches, last-level cache tags or internal 1050 busses. 1051 1052config SCHED_SMT 1053 def_bool y if SMP 1054 1055config SCHED_MC 1056 def_bool y 1057 prompt "Multi-core scheduler support" 1058 depends on SMP 1059 help 1060 Multi-core scheduler support improves the CPU scheduler's decision 1061 making when dealing with multi-core CPU chips at a cost of slightly 1062 increased overhead in some places. If unsure say N here. 1063 1064config SCHED_MC_PRIO 1065 bool "CPU core priorities scheduler support" 1066 depends on SCHED_MC 1067 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1068 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1069 select CPU_FREQ 1070 default y 1071 help 1072 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1073 core ordering determined at manufacturing time, which allows 1074 certain cores to reach higher turbo frequencies (when running 1075 single threaded workloads) than others. 1076 1077 Enabling this kernel feature teaches the scheduler about 1078 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1079 scheduler's CPU selection logic accordingly, so that higher 1080 overall system performance can be achieved. 1081 1082 This feature will have no effect on CPUs without this feature. 1083 1084 If unsure say Y here. 1085 1086config UP_LATE_INIT 1087 def_bool y 1088 depends on !SMP && X86_LOCAL_APIC 1089 1090config X86_UP_APIC 1091 bool "Local APIC support on uniprocessors" if !PCI_MSI 1092 default PCI_MSI 1093 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1094 help 1095 A local APIC (Advanced Programmable Interrupt Controller) is an 1096 integrated interrupt controller in the CPU. If you have a single-CPU 1097 system which has a processor with a local APIC, you can say Y here to 1098 enable and use it. If you say Y here even though your machine doesn't 1099 have a local APIC, then the kernel will still run with no slowdown at 1100 all. The local APIC supports CPU-generated self-interrupts (timer, 1101 performance counters), and the NMI watchdog which detects hard 1102 lockups. 1103 1104config X86_UP_IOAPIC 1105 bool "IO-APIC support on uniprocessors" 1106 depends on X86_UP_APIC 1107 help 1108 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1109 SMP-capable replacement for PC-style interrupt controllers. Most 1110 SMP systems and many recent uniprocessor systems have one. 1111 1112 If you have a single-CPU system with an IO-APIC, you can say Y here 1113 to use it. If you say Y here even though your machine doesn't have 1114 an IO-APIC, then the kernel will still run with no slowdown at all. 1115 1116config X86_LOCAL_APIC 1117 def_bool y 1118 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1119 select IRQ_DOMAIN_HIERARCHY 1120 1121config X86_IO_APIC 1122 def_bool y 1123 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1124 1125config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1126 bool "Reroute for broken boot IRQs" 1127 depends on X86_IO_APIC 1128 help 1129 This option enables a workaround that fixes a source of 1130 spurious interrupts. This is recommended when threaded 1131 interrupt handling is used on systems where the generation of 1132 superfluous "boot interrupts" cannot be disabled. 1133 1134 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1135 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1136 kernel does during interrupt handling). On chipsets where this 1137 boot IRQ generation cannot be disabled, this workaround keeps 1138 the original IRQ line masked so that only the equivalent "boot 1139 IRQ" is delivered to the CPUs. The workaround also tells the 1140 kernel to set up the IRQ handler on the boot IRQ line. In this 1141 way only one interrupt is delivered to the kernel. Otherwise 1142 the spurious second interrupt may cause the kernel to bring 1143 down (vital) interrupt lines. 1144 1145 Only affects "broken" chipsets. Interrupt sharing may be 1146 increased on these systems. 1147 1148config X86_MCE 1149 bool "Machine Check / overheating reporting" 1150 select GENERIC_ALLOCATOR 1151 default y 1152 help 1153 Machine Check support allows the processor to notify the 1154 kernel if it detects a problem (e.g. overheating, data corruption). 1155 The action the kernel takes depends on the severity of the problem, 1156 ranging from warning messages to halting the machine. 1157 1158config X86_MCELOG_LEGACY 1159 bool "Support for deprecated /dev/mcelog character device" 1160 depends on X86_MCE 1161 help 1162 Enable support for /dev/mcelog which is needed by the old mcelog 1163 userspace logging daemon. Consider switching to the new generation 1164 rasdaemon solution. 1165 1166config X86_MCE_INTEL 1167 def_bool y 1168 prompt "Intel MCE features" 1169 depends on X86_MCE && X86_LOCAL_APIC 1170 help 1171 Additional support for intel specific MCE features such as 1172 the thermal monitor. 1173 1174config X86_MCE_AMD 1175 def_bool y 1176 prompt "AMD MCE features" 1177 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1178 help 1179 Additional support for AMD specific MCE features such as 1180 the DRAM Error Threshold. 1181 1182config X86_ANCIENT_MCE 1183 bool "Support for old Pentium 5 / WinChip machine checks" 1184 depends on X86_32 && X86_MCE 1185 help 1186 Include support for machine check handling on old Pentium 5 or WinChip 1187 systems. These typically need to be enabled explicitly on the command 1188 line. 1189 1190config X86_MCE_THRESHOLD 1191 depends on X86_MCE_AMD || X86_MCE_INTEL 1192 def_bool y 1193 1194config X86_MCE_INJECT 1195 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1196 tristate "Machine check injector support" 1197 help 1198 Provide support for injecting machine checks for testing purposes. 1199 If you don't know what a machine check is and you don't do kernel 1200 QA it is safe to say n. 1201 1202source "arch/x86/events/Kconfig" 1203 1204config X86_LEGACY_VM86 1205 bool "Legacy VM86 support" 1206 depends on X86_32 1207 help 1208 This option allows user programs to put the CPU into V8086 1209 mode, which is an 80286-era approximation of 16-bit real mode. 1210 1211 Some very old versions of X and/or vbetool require this option 1212 for user mode setting. Similarly, DOSEMU will use it if 1213 available to accelerate real mode DOS programs. However, any 1214 recent version of DOSEMU, X, or vbetool should be fully 1215 functional even without kernel VM86 support, as they will all 1216 fall back to software emulation. Nevertheless, if you are using 1217 a 16-bit DOS program where 16-bit performance matters, vm86 1218 mode might be faster than emulation and you might want to 1219 enable this option. 1220 1221 Note that any app that works on a 64-bit kernel is unlikely to 1222 need this option, as 64-bit kernels don't, and can't, support 1223 V8086 mode. This option is also unrelated to 16-bit protected 1224 mode and is not needed to run most 16-bit programs under Wine. 1225 1226 Enabling this option increases the complexity of the kernel 1227 and slows down exception handling a tiny bit. 1228 1229 If unsure, say N here. 1230 1231config VM86 1232 bool 1233 default X86_LEGACY_VM86 1234 1235config X86_16BIT 1236 bool "Enable support for 16-bit segments" if EXPERT 1237 default y 1238 depends on MODIFY_LDT_SYSCALL 1239 help 1240 This option is required by programs like Wine to run 16-bit 1241 protected mode legacy code on x86 processors. Disabling 1242 this option saves about 300 bytes on i386, or around 6K text 1243 plus 16K runtime memory on x86-64, 1244 1245config X86_ESPFIX32 1246 def_bool y 1247 depends on X86_16BIT && X86_32 1248 1249config X86_ESPFIX64 1250 def_bool y 1251 depends on X86_16BIT && X86_64 1252 1253config X86_VSYSCALL_EMULATION 1254 bool "Enable vsyscall emulation" if EXPERT 1255 default y 1256 depends on X86_64 1257 help 1258 This enables emulation of the legacy vsyscall page. Disabling 1259 it is roughly equivalent to booting with vsyscall=none, except 1260 that it will also disable the helpful warning if a program 1261 tries to use a vsyscall. With this option set to N, offending 1262 programs will just segfault, citing addresses of the form 1263 0xffffffffff600?00. 1264 1265 This option is required by many programs built before 2013, and 1266 care should be used even with newer programs if set to N. 1267 1268 Disabling this option saves about 7K of kernel size and 1269 possibly 4K of additional runtime pagetable memory. 1270 1271config X86_IOPL_IOPERM 1272 bool "IOPERM and IOPL Emulation" 1273 default y 1274 help 1275 This enables the ioperm() and iopl() syscalls which are necessary 1276 for legacy applications. 1277 1278 Legacy IOPL support is an overbroad mechanism which allows user 1279 space aside of accessing all 65536 I/O ports also to disable 1280 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1281 capabilities and permission from potentially active security 1282 modules. 1283 1284 The emulation restricts the functionality of the syscall to 1285 only allowing the full range I/O port access, but prevents the 1286 ability to disable interrupts from user space which would be 1287 granted if the hardware IOPL mechanism would be used. 1288 1289config TOSHIBA 1290 tristate "Toshiba Laptop support" 1291 depends on X86_32 1292 help 1293 This adds a driver to safely access the System Management Mode of 1294 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1295 not work on models with a Phoenix BIOS. The System Management Mode 1296 is used to set the BIOS and power saving options on Toshiba portables. 1297 1298 For information on utilities to make use of this driver see the 1299 Toshiba Linux utilities web site at: 1300 <http://www.buzzard.org.uk/toshiba/>. 1301 1302 Say Y if you intend to run this kernel on a Toshiba portable. 1303 Say N otherwise. 1304 1305config X86_REBOOTFIXUPS 1306 bool "Enable X86 board specific fixups for reboot" 1307 depends on X86_32 1308 help 1309 This enables chipset and/or board specific fixups to be done 1310 in order to get reboot to work correctly. This is only needed on 1311 some combinations of hardware and BIOS. The symptom, for which 1312 this config is intended, is when reboot ends with a stalled/hung 1313 system. 1314 1315 Currently, the only fixup is for the Geode machines using 1316 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1317 1318 Say Y if you want to enable the fixup. Currently, it's safe to 1319 enable this option even if you don't need it. 1320 Say N otherwise. 1321 1322config MICROCODE 1323 def_bool y 1324 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1325 1326config MICROCODE_INITRD32 1327 def_bool y 1328 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1329 1330config MICROCODE_LATE_LOADING 1331 bool "Late microcode loading (DANGEROUS)" 1332 default n 1333 depends on MICROCODE && SMP 1334 help 1335 Loading microcode late, when the system is up and executing instructions 1336 is a tricky business and should be avoided if possible. Just the sequence 1337 of synchronizing all cores and SMT threads is one fragile dance which does 1338 not guarantee that cores might not softlock after the loading. Therefore, 1339 use this at your own risk. Late loading taints the kernel unless the 1340 microcode header indicates that it is safe for late loading via the 1341 minimal revision check. This minimal revision check can be enforced on 1342 the kernel command line with "microcode.minrev=Y". 1343 1344config MICROCODE_LATE_FORCE_MINREV 1345 bool "Enforce late microcode loading minimal revision check" 1346 default n 1347 depends on MICROCODE_LATE_LOADING 1348 help 1349 To prevent that users load microcode late which modifies already 1350 in use features, newer microcode patches have a minimum revision field 1351 in the microcode header, which tells the kernel which minimum 1352 revision must be active in the CPU to safely load that new microcode 1353 late into the running system. If disabled the check will not 1354 be enforced but the kernel will be tainted when the minimal 1355 revision check fails. 1356 1357 This minimal revision check can also be controlled via the 1358 "microcode.minrev" parameter on the kernel command line. 1359 1360 If unsure say Y. 1361 1362config X86_MSR 1363 tristate "/dev/cpu/*/msr - Model-specific register support" 1364 help 1365 This device gives privileged processes access to the x86 1366 Model-Specific Registers (MSRs). It is a character device with 1367 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1368 MSR accesses are directed to a specific CPU on multi-processor 1369 systems. 1370 1371config X86_CPUID 1372 tristate "/dev/cpu/*/cpuid - CPU information support" 1373 help 1374 This device gives processes access to the x86 CPUID instruction to 1375 be executed on a specific processor. It is a character device 1376 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1377 /dev/cpu/31/cpuid. 1378 1379choice 1380 prompt "High Memory Support" 1381 default HIGHMEM4G 1382 depends on X86_32 1383 1384config NOHIGHMEM 1385 bool "off" 1386 help 1387 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1388 However, the address space of 32-bit x86 processors is only 4 1389 Gigabytes large. That means that, if you have a large amount of 1390 physical memory, not all of it can be "permanently mapped" by the 1391 kernel. The physical memory that's not permanently mapped is called 1392 "high memory". 1393 1394 If you are compiling a kernel which will never run on a machine with 1395 more than 1 Gigabyte total physical RAM, answer "off" here (default 1396 choice and suitable for most users). This will result in a "3GB/1GB" 1397 split: 3GB are mapped so that each process sees a 3GB virtual memory 1398 space and the remaining part of the 4GB virtual memory space is used 1399 by the kernel to permanently map as much physical memory as 1400 possible. 1401 1402 If the machine has between 1 and 4 Gigabytes physical RAM, then 1403 answer "4GB" here. 1404 1405 If more than 4 Gigabytes is used then answer "64GB" here. This 1406 selection turns Intel PAE (Physical Address Extension) mode on. 1407 PAE implements 3-level paging on IA32 processors. PAE is fully 1408 supported by Linux, PAE mode is implemented on all recent Intel 1409 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1410 then the kernel will not boot on CPUs that don't support PAE! 1411 1412 The actual amount of total physical memory will either be 1413 auto detected or can be forced by using a kernel command line option 1414 such as "mem=256M". (Try "man bootparam" or see the documentation of 1415 your boot loader (lilo or loadlin) about how to pass options to the 1416 kernel at boot time.) 1417 1418 If unsure, say "off". 1419 1420config HIGHMEM4G 1421 bool "4GB" 1422 help 1423 Select this if you have a 32-bit processor and between 1 and 4 1424 gigabytes of physical RAM. 1425 1426config HIGHMEM64G 1427 bool "64GB" 1428 depends on X86_HAVE_PAE 1429 select X86_PAE 1430 help 1431 Select this if you have a 32-bit processor and more than 4 1432 gigabytes of physical RAM. 1433 1434endchoice 1435 1436choice 1437 prompt "Memory split" if EXPERT 1438 default VMSPLIT_3G 1439 depends on X86_32 1440 help 1441 Select the desired split between kernel and user memory. 1442 1443 If the address range available to the kernel is less than the 1444 physical memory installed, the remaining memory will be available 1445 as "high memory". Accessing high memory is a little more costly 1446 than low memory, as it needs to be mapped into the kernel first. 1447 Note that increasing the kernel address space limits the range 1448 available to user programs, making the address space there 1449 tighter. Selecting anything other than the default 3G/1G split 1450 will also likely make your kernel incompatible with binary-only 1451 kernel modules. 1452 1453 If you are not absolutely sure what you are doing, leave this 1454 option alone! 1455 1456 config VMSPLIT_3G 1457 bool "3G/1G user/kernel split" 1458 config VMSPLIT_3G_OPT 1459 depends on !X86_PAE 1460 bool "3G/1G user/kernel split (for full 1G low memory)" 1461 config VMSPLIT_2G 1462 bool "2G/2G user/kernel split" 1463 config VMSPLIT_2G_OPT 1464 depends on !X86_PAE 1465 bool "2G/2G user/kernel split (for full 2G low memory)" 1466 config VMSPLIT_1G 1467 bool "1G/3G user/kernel split" 1468endchoice 1469 1470config PAGE_OFFSET 1471 hex 1472 default 0xB0000000 if VMSPLIT_3G_OPT 1473 default 0x80000000 if VMSPLIT_2G 1474 default 0x78000000 if VMSPLIT_2G_OPT 1475 default 0x40000000 if VMSPLIT_1G 1476 default 0xC0000000 1477 depends on X86_32 1478 1479config HIGHMEM 1480 def_bool y 1481 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1482 1483config X86_PAE 1484 bool "PAE (Physical Address Extension) Support" 1485 depends on X86_32 && X86_HAVE_PAE 1486 select PHYS_ADDR_T_64BIT 1487 select SWIOTLB 1488 help 1489 PAE is required for NX support, and furthermore enables 1490 larger swapspace support for non-overcommit purposes. It 1491 has the cost of more pagetable lookup overhead, and also 1492 consumes more pagetable space per process. 1493 1494config X86_5LEVEL 1495 bool "Enable 5-level page tables support" 1496 default y 1497 select DYNAMIC_MEMORY_LAYOUT 1498 select SPARSEMEM_VMEMMAP 1499 depends on X86_64 1500 help 1501 5-level paging enables access to larger address space: 1502 up to 128 PiB of virtual address space and 4 PiB of 1503 physical address space. 1504 1505 It will be supported by future Intel CPUs. 1506 1507 A kernel with the option enabled can be booted on machines that 1508 support 4- or 5-level paging. 1509 1510 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1511 information. 1512 1513 Say N if unsure. 1514 1515config X86_DIRECT_GBPAGES 1516 def_bool y 1517 depends on X86_64 1518 help 1519 Certain kernel features effectively disable kernel 1520 linear 1 GB mappings (even if the CPU otherwise 1521 supports them), so don't confuse the user by printing 1522 that we have them enabled. 1523 1524config X86_CPA_STATISTICS 1525 bool "Enable statistic for Change Page Attribute" 1526 depends on DEBUG_FS 1527 help 1528 Expose statistics about the Change Page Attribute mechanism, which 1529 helps to determine the effectiveness of preserving large and huge 1530 page mappings when mapping protections are changed. 1531 1532config X86_MEM_ENCRYPT 1533 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1534 select DYNAMIC_PHYSICAL_MASK 1535 def_bool n 1536 1537config AMD_MEM_ENCRYPT 1538 bool "AMD Secure Memory Encryption (SME) support" 1539 depends on X86_64 && CPU_SUP_AMD 1540 depends on EFI_STUB 1541 select DMA_COHERENT_POOL 1542 select ARCH_USE_MEMREMAP_PROT 1543 select INSTRUCTION_DECODER 1544 select ARCH_HAS_CC_PLATFORM 1545 select X86_MEM_ENCRYPT 1546 select UNACCEPTED_MEMORY 1547 help 1548 Say yes to enable support for the encryption of system memory. 1549 This requires an AMD processor that supports Secure Memory 1550 Encryption (SME). 1551 1552# Common NUMA Features 1553config NUMA 1554 bool "NUMA Memory Allocation and Scheduler Support" 1555 depends on SMP 1556 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1557 default y if X86_BIGSMP 1558 select USE_PERCPU_NUMA_NODE_ID 1559 select OF_NUMA if OF 1560 help 1561 Enable NUMA (Non-Uniform Memory Access) support. 1562 1563 The kernel will try to allocate memory used by a CPU on the 1564 local memory controller of the CPU and add some more 1565 NUMA awareness to the kernel. 1566 1567 For 64-bit this is recommended if the system is Intel Core i7 1568 (or later), AMD Opteron, or EM64T NUMA. 1569 1570 For 32-bit this is only needed if you boot a 32-bit 1571 kernel on a 64-bit NUMA platform. 1572 1573 Otherwise, you should say N. 1574 1575config AMD_NUMA 1576 def_bool y 1577 prompt "Old style AMD Opteron NUMA detection" 1578 depends on X86_64 && NUMA && PCI 1579 help 1580 Enable AMD NUMA node topology detection. You should say Y here if 1581 you have a multi processor AMD system. This uses an old method to 1582 read the NUMA configuration directly from the builtin Northbridge 1583 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1584 which also takes priority if both are compiled in. 1585 1586config X86_64_ACPI_NUMA 1587 def_bool y 1588 prompt "ACPI NUMA detection" 1589 depends on X86_64 && NUMA && ACPI && PCI 1590 select ACPI_NUMA 1591 help 1592 Enable ACPI SRAT based node topology detection. 1593 1594config NUMA_EMU 1595 bool "NUMA emulation" 1596 depends on NUMA 1597 help 1598 Enable NUMA emulation. A flat machine will be split 1599 into virtual nodes when booted with "numa=fake=N", where N is the 1600 number of nodes. This is only useful for debugging. 1601 1602config NODES_SHIFT 1603 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1604 range 1 10 1605 default "10" if MAXSMP 1606 default "6" if X86_64 1607 default "3" 1608 depends on NUMA 1609 help 1610 Specify the maximum number of NUMA Nodes available on the target 1611 system. Increases memory reserved to accommodate various tables. 1612 1613config ARCH_FLATMEM_ENABLE 1614 def_bool y 1615 depends on X86_32 && !NUMA 1616 1617config ARCH_SPARSEMEM_ENABLE 1618 def_bool y 1619 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1620 select SPARSEMEM_STATIC if X86_32 1621 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1622 1623config ARCH_SPARSEMEM_DEFAULT 1624 def_bool X86_64 || (NUMA && X86_32) 1625 1626config ARCH_SELECT_MEMORY_MODEL 1627 def_bool y 1628 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1629 1630config ARCH_MEMORY_PROBE 1631 bool "Enable sysfs memory/probe interface" 1632 depends on MEMORY_HOTPLUG 1633 help 1634 This option enables a sysfs memory/probe interface for testing. 1635 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1636 If you are unsure how to answer this question, answer N. 1637 1638config ARCH_PROC_KCORE_TEXT 1639 def_bool y 1640 depends on X86_64 && PROC_KCORE 1641 1642config ILLEGAL_POINTER_VALUE 1643 hex 1644 default 0 if X86_32 1645 default 0xdead000000000000 if X86_64 1646 1647config X86_PMEM_LEGACY_DEVICE 1648 bool 1649 1650config X86_PMEM_LEGACY 1651 tristate "Support non-standard NVDIMMs and ADR protected memory" 1652 depends on PHYS_ADDR_T_64BIT 1653 depends on BLK_DEV 1654 select X86_PMEM_LEGACY_DEVICE 1655 select NUMA_KEEP_MEMINFO if NUMA 1656 select LIBNVDIMM 1657 help 1658 Treat memory marked using the non-standard e820 type of 12 as used 1659 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1660 The kernel will offer these regions to the 'pmem' driver so 1661 they can be used for persistent storage. 1662 1663 Say Y if unsure. 1664 1665config HIGHPTE 1666 bool "Allocate 3rd-level pagetables from highmem" 1667 depends on HIGHMEM 1668 help 1669 The VM uses one page table entry for each page of physical memory. 1670 For systems with a lot of RAM, this can be wasteful of precious 1671 low memory. Setting this option will put user-space page table 1672 entries in high memory. 1673 1674config X86_CHECK_BIOS_CORRUPTION 1675 bool "Check for low memory corruption" 1676 help 1677 Periodically check for memory corruption in low memory, which 1678 is suspected to be caused by BIOS. Even when enabled in the 1679 configuration, it is disabled at runtime. Enable it by 1680 setting "memory_corruption_check=1" on the kernel command 1681 line. By default it scans the low 64k of memory every 60 1682 seconds; see the memory_corruption_check_size and 1683 memory_corruption_check_period parameters in 1684 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1685 1686 When enabled with the default parameters, this option has 1687 almost no overhead, as it reserves a relatively small amount 1688 of memory and scans it infrequently. It both detects corruption 1689 and prevents it from affecting the running system. 1690 1691 It is, however, intended as a diagnostic tool; if repeatable 1692 BIOS-originated corruption always affects the same memory, 1693 you can use memmap= to prevent the kernel from using that 1694 memory. 1695 1696config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1697 bool "Set the default setting of memory_corruption_check" 1698 depends on X86_CHECK_BIOS_CORRUPTION 1699 default y 1700 help 1701 Set whether the default state of memory_corruption_check is 1702 on or off. 1703 1704config MATH_EMULATION 1705 bool 1706 depends on MODIFY_LDT_SYSCALL 1707 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1708 help 1709 Linux can emulate a math coprocessor (used for floating point 1710 operations) if you don't have one. 486DX and Pentium processors have 1711 a math coprocessor built in, 486SX and 386 do not, unless you added 1712 a 487DX or 387, respectively. (The messages during boot time can 1713 give you some hints here ["man dmesg"].) Everyone needs either a 1714 coprocessor or this emulation. 1715 1716 If you don't have a math coprocessor, you need to say Y here; if you 1717 say Y here even though you have a coprocessor, the coprocessor will 1718 be used nevertheless. (This behavior can be changed with the kernel 1719 command line option "no387", which comes handy if your coprocessor 1720 is broken. Try "man bootparam" or see the documentation of your boot 1721 loader (lilo or loadlin) about how to pass options to the kernel at 1722 boot time.) This means that it is a good idea to say Y here if you 1723 intend to use this kernel on different machines. 1724 1725 More information about the internals of the Linux math coprocessor 1726 emulation can be found in <file:arch/x86/math-emu/README>. 1727 1728 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1729 kernel, it won't hurt. 1730 1731config MTRR 1732 def_bool y 1733 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1734 help 1735 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1736 the Memory Type Range Registers (MTRRs) may be used to control 1737 processor access to memory ranges. This is most useful if you have 1738 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1739 allows bus write transfers to be combined into a larger transfer 1740 before bursting over the PCI/AGP bus. This can increase performance 1741 of image write operations 2.5 times or more. Saying Y here creates a 1742 /proc/mtrr file which may be used to manipulate your processor's 1743 MTRRs. Typically the X server should use this. 1744 1745 This code has a reasonably generic interface so that similar 1746 control registers on other processors can be easily supported 1747 as well: 1748 1749 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1750 Registers (ARRs) which provide a similar functionality to MTRRs. For 1751 these, the ARRs are used to emulate the MTRRs. 1752 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1753 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1754 write-combining. All of these processors are supported by this code 1755 and it makes sense to say Y here if you have one of them. 1756 1757 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1758 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1759 can lead to all sorts of problems, so it's good to say Y here. 1760 1761 You can safely say Y even if your machine doesn't have MTRRs, you'll 1762 just add about 9 KB to your kernel. 1763 1764 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1765 1766config MTRR_SANITIZER 1767 def_bool y 1768 prompt "MTRR cleanup support" 1769 depends on MTRR 1770 help 1771 Convert MTRR layout from continuous to discrete, so X drivers can 1772 add writeback entries. 1773 1774 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1775 The largest mtrr entry size for a continuous block can be set with 1776 mtrr_chunk_size. 1777 1778 If unsure, say Y. 1779 1780config MTRR_SANITIZER_ENABLE_DEFAULT 1781 int "MTRR cleanup enable value (0-1)" 1782 range 0 1 1783 default "0" 1784 depends on MTRR_SANITIZER 1785 help 1786 Enable mtrr cleanup default value 1787 1788config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1789 int "MTRR cleanup spare reg num (0-7)" 1790 range 0 7 1791 default "1" 1792 depends on MTRR_SANITIZER 1793 help 1794 mtrr cleanup spare entries default, it can be changed via 1795 mtrr_spare_reg_nr=N on the kernel command line. 1796 1797config X86_PAT 1798 def_bool y 1799 prompt "x86 PAT support" if EXPERT 1800 depends on MTRR 1801 help 1802 Use PAT attributes to setup page level cache control. 1803 1804 PATs are the modern equivalents of MTRRs and are much more 1805 flexible than MTRRs. 1806 1807 Say N here if you see bootup problems (boot crash, boot hang, 1808 spontaneous reboots) or a non-working video driver. 1809 1810 If unsure, say Y. 1811 1812config ARCH_USES_PG_UNCACHED 1813 def_bool y 1814 depends on X86_PAT 1815 1816config X86_UMIP 1817 def_bool y 1818 prompt "User Mode Instruction Prevention" if EXPERT 1819 help 1820 User Mode Instruction Prevention (UMIP) is a security feature in 1821 some x86 processors. If enabled, a general protection fault is 1822 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1823 executed in user mode. These instructions unnecessarily expose 1824 information about the hardware state. 1825 1826 The vast majority of applications do not use these instructions. 1827 For the very few that do, software emulation is provided in 1828 specific cases in protected and virtual-8086 modes. Emulated 1829 results are dummy. 1830 1831config CC_HAS_IBT 1832 # GCC >= 9 and binutils >= 2.29 1833 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1834 # Clang/LLVM >= 14 1835 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1836 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1837 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1838 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1839 $(as-instr,endbr64) 1840 1841config X86_CET 1842 def_bool n 1843 help 1844 CET features configured (Shadow stack or IBT) 1845 1846config X86_KERNEL_IBT 1847 prompt "Indirect Branch Tracking" 1848 def_bool y 1849 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1850 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1851 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1852 select OBJTOOL 1853 select X86_CET 1854 help 1855 Build the kernel with support for Indirect Branch Tracking, a 1856 hardware support course-grain forward-edge Control Flow Integrity 1857 protection. It enforces that all indirect calls must land on 1858 an ENDBR instruction, as such, the compiler will instrument the 1859 code with them to make this happen. 1860 1861 In addition to building the kernel with IBT, seal all functions that 1862 are not indirect call targets, avoiding them ever becoming one. 1863 1864 This requires LTO like objtool runs and will slow down the build. It 1865 does significantly reduce the number of ENDBR instructions in the 1866 kernel image. 1867 1868config X86_INTEL_MEMORY_PROTECTION_KEYS 1869 prompt "Memory Protection Keys" 1870 def_bool y 1871 # Note: only available in 64-bit mode 1872 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1873 select ARCH_USES_HIGH_VMA_FLAGS 1874 select ARCH_HAS_PKEYS 1875 help 1876 Memory Protection Keys provides a mechanism for enforcing 1877 page-based protections, but without requiring modification of the 1878 page tables when an application changes protection domains. 1879 1880 For details, see Documentation/core-api/protection-keys.rst 1881 1882 If unsure, say y. 1883 1884choice 1885 prompt "TSX enable mode" 1886 depends on CPU_SUP_INTEL 1887 default X86_INTEL_TSX_MODE_OFF 1888 help 1889 Intel's TSX (Transactional Synchronization Extensions) feature 1890 allows to optimize locking protocols through lock elision which 1891 can lead to a noticeable performance boost. 1892 1893 On the other hand it has been shown that TSX can be exploited 1894 to form side channel attacks (e.g. TAA) and chances are there 1895 will be more of those attacks discovered in the future. 1896 1897 Therefore TSX is not enabled by default (aka tsx=off). An admin 1898 might override this decision by tsx=on the command line parameter. 1899 Even with TSX enabled, the kernel will attempt to enable the best 1900 possible TAA mitigation setting depending on the microcode available 1901 for the particular machine. 1902 1903 This option allows to set the default tsx mode between tsx=on, =off 1904 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1905 details. 1906 1907 Say off if not sure, auto if TSX is in use but it should be used on safe 1908 platforms or on if TSX is in use and the security aspect of tsx is not 1909 relevant. 1910 1911config X86_INTEL_TSX_MODE_OFF 1912 bool "off" 1913 help 1914 TSX is disabled if possible - equals to tsx=off command line parameter. 1915 1916config X86_INTEL_TSX_MODE_ON 1917 bool "on" 1918 help 1919 TSX is always enabled on TSX capable HW - equals the tsx=on command 1920 line parameter. 1921 1922config X86_INTEL_TSX_MODE_AUTO 1923 bool "auto" 1924 help 1925 TSX is enabled on TSX capable HW that is believed to be safe against 1926 side channel attacks- equals the tsx=auto command line parameter. 1927endchoice 1928 1929config X86_SGX 1930 bool "Software Guard eXtensions (SGX)" 1931 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1932 depends on CRYPTO=y 1933 depends on CRYPTO_SHA256=y 1934 select MMU_NOTIFIER 1935 select NUMA_KEEP_MEMINFO if NUMA 1936 select XARRAY_MULTI 1937 help 1938 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1939 that can be used by applications to set aside private regions of code 1940 and data, referred to as enclaves. An enclave's private memory can 1941 only be accessed by code running within the enclave. Accesses from 1942 outside the enclave, including other enclaves, are disallowed by 1943 hardware. 1944 1945 If unsure, say N. 1946 1947config X86_USER_SHADOW_STACK 1948 bool "X86 userspace shadow stack" 1949 depends on AS_WRUSS 1950 depends on X86_64 1951 select ARCH_USES_HIGH_VMA_FLAGS 1952 select X86_CET 1953 help 1954 Shadow stack protection is a hardware feature that detects function 1955 return address corruption. This helps mitigate ROP attacks. 1956 Applications must be enabled to use it, and old userspace does not 1957 get protection "for free". 1958 1959 CPUs supporting shadow stacks were first released in 2020. 1960 1961 See Documentation/arch/x86/shstk.rst for more information. 1962 1963 If unsure, say N. 1964 1965config INTEL_TDX_HOST 1966 bool "Intel Trust Domain Extensions (TDX) host support" 1967 depends on CPU_SUP_INTEL 1968 depends on X86_64 1969 depends on KVM_INTEL 1970 depends on X86_X2APIC 1971 select ARCH_KEEP_MEMBLOCK 1972 depends on CONTIG_ALLOC 1973 depends on !KEXEC_CORE 1974 depends on X86_MCE 1975 help 1976 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1977 host and certain physical attacks. This option enables necessary TDX 1978 support in the host kernel to run confidential VMs. 1979 1980 If unsure, say N. 1981 1982config EFI 1983 bool "EFI runtime service support" 1984 depends on ACPI 1985 select UCS2_STRING 1986 select EFI_RUNTIME_WRAPPERS 1987 select ARCH_USE_MEMREMAP_PROT 1988 select EFI_RUNTIME_MAP if KEXEC_CORE 1989 help 1990 This enables the kernel to use EFI runtime services that are 1991 available (such as the EFI variable services). 1992 1993 This option is only useful on systems that have EFI firmware. 1994 In addition, you should use the latest ELILO loader available 1995 at <http://elilo.sourceforge.net> in order to take advantage 1996 of EFI runtime services. However, even with this option, the 1997 resultant kernel should continue to boot on existing non-EFI 1998 platforms. 1999 2000config EFI_STUB 2001 bool "EFI stub support" 2002 depends on EFI 2003 select RELOCATABLE 2004 help 2005 This kernel feature allows a bzImage to be loaded directly 2006 by EFI firmware without the use of a bootloader. 2007 2008 See Documentation/admin-guide/efi-stub.rst for more information. 2009 2010config EFI_HANDOVER_PROTOCOL 2011 bool "EFI handover protocol (DEPRECATED)" 2012 depends on EFI_STUB 2013 default y 2014 help 2015 Select this in order to include support for the deprecated EFI 2016 handover protocol, which defines alternative entry points into the 2017 EFI stub. This is a practice that has no basis in the UEFI 2018 specification, and requires a priori knowledge on the part of the 2019 bootloader about Linux/x86 specific ways of passing the command line 2020 and initrd, and where in memory those assets may be loaded. 2021 2022 If in doubt, say Y. Even though the corresponding support is not 2023 present in upstream GRUB or other bootloaders, most distros build 2024 GRUB with numerous downstream patches applied, and may rely on the 2025 handover protocol as as result. 2026 2027config EFI_MIXED 2028 bool "EFI mixed-mode support" 2029 depends on EFI_STUB && X86_64 2030 help 2031 Enabling this feature allows a 64-bit kernel to be booted 2032 on a 32-bit firmware, provided that your CPU supports 64-bit 2033 mode. 2034 2035 Note that it is not possible to boot a mixed-mode enabled 2036 kernel via the EFI boot stub - a bootloader that supports 2037 the EFI handover protocol must be used. 2038 2039 If unsure, say N. 2040 2041config EFI_FAKE_MEMMAP 2042 bool "Enable EFI fake memory map" 2043 depends on EFI 2044 help 2045 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2046 this parameter, you can add arbitrary attribute to specific memory 2047 range by updating original (firmware provided) EFI memmap. This is 2048 useful for debugging of EFI memmap related feature, e.g., Address 2049 Range Mirroring feature. 2050 2051config EFI_MAX_FAKE_MEM 2052 int "maximum allowable number of ranges in efi_fake_mem boot option" 2053 depends on EFI_FAKE_MEMMAP 2054 range 1 128 2055 default 8 2056 help 2057 Maximum allowable number of ranges in efi_fake_mem boot option. 2058 Ranges can be set up to this value using comma-separated list. 2059 The default value is 8. 2060 2061config EFI_RUNTIME_MAP 2062 bool "Export EFI runtime maps to sysfs" if EXPERT 2063 depends on EFI 2064 help 2065 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2066 That memory map is required by the 2nd kernel to set up EFI virtual 2067 mappings after kexec, but can also be used for debugging purposes. 2068 2069 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2070 2071source "kernel/Kconfig.hz" 2072 2073config ARCH_SUPPORTS_KEXEC 2074 def_bool y 2075 2076config ARCH_SUPPORTS_KEXEC_FILE 2077 def_bool X86_64 2078 2079config ARCH_SELECTS_KEXEC_FILE 2080 def_bool y 2081 depends on KEXEC_FILE 2082 select HAVE_IMA_KEXEC if IMA 2083 2084config ARCH_SUPPORTS_KEXEC_PURGATORY 2085 def_bool y 2086 2087config ARCH_SUPPORTS_KEXEC_SIG 2088 def_bool y 2089 2090config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2091 def_bool y 2092 2093config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2094 def_bool y 2095 2096config ARCH_SUPPORTS_KEXEC_JUMP 2097 def_bool y 2098 2099config ARCH_SUPPORTS_CRASH_DUMP 2100 def_bool X86_64 || (X86_32 && HIGHMEM) 2101 2102config ARCH_SUPPORTS_CRASH_HOTPLUG 2103 def_bool y 2104 2105config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2106 def_bool CRASH_RESERVE 2107 2108config PHYSICAL_START 2109 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2110 default "0x1000000" 2111 help 2112 This gives the physical address where the kernel is loaded. 2113 2114 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2115 will decompress itself to above physical address and run from there. 2116 Otherwise, bzImage will run from the address where it has been loaded 2117 by the boot loader. The only exception is if it is loaded below the 2118 above physical address, in which case it will relocate itself there. 2119 2120 In normal kdump cases one does not have to set/change this option 2121 as now bzImage can be compiled as a completely relocatable image 2122 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2123 address. This option is mainly useful for the folks who don't want 2124 to use a bzImage for capturing the crash dump and want to use a 2125 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2126 to be specifically compiled to run from a specific memory area 2127 (normally a reserved region) and this option comes handy. 2128 2129 So if you are using bzImage for capturing the crash dump, 2130 leave the value here unchanged to 0x1000000 and set 2131 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2132 for capturing the crash dump change this value to start of 2133 the reserved region. In other words, it can be set based on 2134 the "X" value as specified in the "crashkernel=YM@XM" 2135 command line boot parameter passed to the panic-ed 2136 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2137 for more details about crash dumps. 2138 2139 Usage of bzImage for capturing the crash dump is recommended as 2140 one does not have to build two kernels. Same kernel can be used 2141 as production kernel and capture kernel. Above option should have 2142 gone away after relocatable bzImage support is introduced. But it 2143 is present because there are users out there who continue to use 2144 vmlinux for dump capture. This option should go away down the 2145 line. 2146 2147 Don't change this unless you know what you are doing. 2148 2149config RELOCATABLE 2150 bool "Build a relocatable kernel" 2151 default y 2152 help 2153 This builds a kernel image that retains relocation information 2154 so it can be loaded someplace besides the default 1MB. 2155 The relocations tend to make the kernel binary about 10% larger, 2156 but are discarded at runtime. 2157 2158 One use is for the kexec on panic case where the recovery kernel 2159 must live at a different physical address than the primary 2160 kernel. 2161 2162 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2163 it has been loaded at and the compile time physical address 2164 (CONFIG_PHYSICAL_START) is used as the minimum location. 2165 2166config RANDOMIZE_BASE 2167 bool "Randomize the address of the kernel image (KASLR)" 2168 depends on RELOCATABLE 2169 default y 2170 help 2171 In support of Kernel Address Space Layout Randomization (KASLR), 2172 this randomizes the physical address at which the kernel image 2173 is decompressed and the virtual address where the kernel 2174 image is mapped, as a security feature that deters exploit 2175 attempts relying on knowledge of the location of kernel 2176 code internals. 2177 2178 On 64-bit, the kernel physical and virtual addresses are 2179 randomized separately. The physical address will be anywhere 2180 between 16MB and the top of physical memory (up to 64TB). The 2181 virtual address will be randomized from 16MB up to 1GB (9 bits 2182 of entropy). Note that this also reduces the memory space 2183 available to kernel modules from 1.5GB to 1GB. 2184 2185 On 32-bit, the kernel physical and virtual addresses are 2186 randomized together. They will be randomized from 16MB up to 2187 512MB (8 bits of entropy). 2188 2189 Entropy is generated using the RDRAND instruction if it is 2190 supported. If RDTSC is supported, its value is mixed into 2191 the entropy pool as well. If neither RDRAND nor RDTSC are 2192 supported, then entropy is read from the i8254 timer. The 2193 usable entropy is limited by the kernel being built using 2194 2GB addressing, and that PHYSICAL_ALIGN must be at a 2195 minimum of 2MB. As a result, only 10 bits of entropy are 2196 theoretically possible, but the implementations are further 2197 limited due to memory layouts. 2198 2199 If unsure, say Y. 2200 2201# Relocation on x86 needs some additional build support 2202config X86_NEED_RELOCS 2203 def_bool y 2204 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2205 2206config PHYSICAL_ALIGN 2207 hex "Alignment value to which kernel should be aligned" 2208 default "0x200000" 2209 range 0x2000 0x1000000 if X86_32 2210 range 0x200000 0x1000000 if X86_64 2211 help 2212 This value puts the alignment restrictions on physical address 2213 where kernel is loaded and run from. Kernel is compiled for an 2214 address which meets above alignment restriction. 2215 2216 If bootloader loads the kernel at a non-aligned address and 2217 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2218 address aligned to above value and run from there. 2219 2220 If bootloader loads the kernel at a non-aligned address and 2221 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2222 load address and decompress itself to the address it has been 2223 compiled for and run from there. The address for which kernel is 2224 compiled already meets above alignment restrictions. Hence the 2225 end result is that kernel runs from a physical address meeting 2226 above alignment restrictions. 2227 2228 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2229 this value must be a multiple of 0x200000. 2230 2231 Don't change this unless you know what you are doing. 2232 2233config DYNAMIC_MEMORY_LAYOUT 2234 bool 2235 help 2236 This option makes base addresses of vmalloc and vmemmap as well as 2237 __PAGE_OFFSET movable during boot. 2238 2239config RANDOMIZE_MEMORY 2240 bool "Randomize the kernel memory sections" 2241 depends on X86_64 2242 depends on RANDOMIZE_BASE 2243 select DYNAMIC_MEMORY_LAYOUT 2244 default RANDOMIZE_BASE 2245 help 2246 Randomizes the base virtual address of kernel memory sections 2247 (physical memory mapping, vmalloc & vmemmap). This security feature 2248 makes exploits relying on predictable memory locations less reliable. 2249 2250 The order of allocations remains unchanged. Entropy is generated in 2251 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2252 configuration have in average 30,000 different possible virtual 2253 addresses for each memory section. 2254 2255 If unsure, say Y. 2256 2257config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2258 hex "Physical memory mapping padding" if EXPERT 2259 depends on RANDOMIZE_MEMORY 2260 default "0xa" if MEMORY_HOTPLUG 2261 default "0x0" 2262 range 0x1 0x40 if MEMORY_HOTPLUG 2263 range 0x0 0x40 2264 help 2265 Define the padding in terabytes added to the existing physical 2266 memory size during kernel memory randomization. It is useful 2267 for memory hotplug support but reduces the entropy available for 2268 address randomization. 2269 2270 If unsure, leave at the default value. 2271 2272config ADDRESS_MASKING 2273 bool "Linear Address Masking support" 2274 depends on X86_64 2275 help 2276 Linear Address Masking (LAM) modifies the checking that is applied 2277 to 64-bit linear addresses, allowing software to use of the 2278 untranslated address bits for metadata. 2279 2280 The capability can be used for efficient address sanitizers (ASAN) 2281 implementation and for optimizations in JITs. 2282 2283config HOTPLUG_CPU 2284 def_bool y 2285 depends on SMP 2286 2287config COMPAT_VDSO 2288 def_bool n 2289 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2290 depends on COMPAT_32 2291 help 2292 Certain buggy versions of glibc will crash if they are 2293 presented with a 32-bit vDSO that is not mapped at the address 2294 indicated in its segment table. 2295 2296 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2297 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2298 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2299 the only released version with the bug, but OpenSUSE 9 2300 contains a buggy "glibc 2.3.2". 2301 2302 The symptom of the bug is that everything crashes on startup, saying: 2303 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2304 2305 Saying Y here changes the default value of the vdso32 boot 2306 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2307 This works around the glibc bug but hurts performance. 2308 2309 If unsure, say N: if you are compiling your own kernel, you 2310 are unlikely to be using a buggy version of glibc. 2311 2312choice 2313 prompt "vsyscall table for legacy applications" 2314 depends on X86_64 2315 default LEGACY_VSYSCALL_XONLY 2316 help 2317 Legacy user code that does not know how to find the vDSO expects 2318 to be able to issue three syscalls by calling fixed addresses in 2319 kernel space. Since this location is not randomized with ASLR, 2320 it can be used to assist security vulnerability exploitation. 2321 2322 This setting can be changed at boot time via the kernel command 2323 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2324 is deprecated and can only be enabled using the kernel command 2325 line. 2326 2327 On a system with recent enough glibc (2.14 or newer) and no 2328 static binaries, you can say None without a performance penalty 2329 to improve security. 2330 2331 If unsure, select "Emulate execution only". 2332 2333 config LEGACY_VSYSCALL_XONLY 2334 bool "Emulate execution only" 2335 help 2336 The kernel traps and emulates calls into the fixed vsyscall 2337 address mapping and does not allow reads. This 2338 configuration is recommended when userspace might use the 2339 legacy vsyscall area but support for legacy binary 2340 instrumentation of legacy code is not needed. It mitigates 2341 certain uses of the vsyscall area as an ASLR-bypassing 2342 buffer. 2343 2344 config LEGACY_VSYSCALL_NONE 2345 bool "None" 2346 help 2347 There will be no vsyscall mapping at all. This will 2348 eliminate any risk of ASLR bypass due to the vsyscall 2349 fixed address mapping. Attempts to use the vsyscalls 2350 will be reported to dmesg, so that either old or 2351 malicious userspace programs can be identified. 2352 2353endchoice 2354 2355config CMDLINE_BOOL 2356 bool "Built-in kernel command line" 2357 help 2358 Allow for specifying boot arguments to the kernel at 2359 build time. On some systems (e.g. embedded ones), it is 2360 necessary or convenient to provide some or all of the 2361 kernel boot arguments with the kernel itself (that is, 2362 to not rely on the boot loader to provide them.) 2363 2364 To compile command line arguments into the kernel, 2365 set this option to 'Y', then fill in the 2366 boot arguments in CONFIG_CMDLINE. 2367 2368 Systems with fully functional boot loaders (i.e. non-embedded) 2369 should leave this option set to 'N'. 2370 2371config CMDLINE 2372 string "Built-in kernel command string" 2373 depends on CMDLINE_BOOL 2374 default "" 2375 help 2376 Enter arguments here that should be compiled into the kernel 2377 image and used at boot time. If the boot loader provides a 2378 command line at boot time, it is appended to this string to 2379 form the full kernel command line, when the system boots. 2380 2381 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2382 change this behavior. 2383 2384 In most cases, the command line (whether built-in or provided 2385 by the boot loader) should specify the device for the root 2386 file system. 2387 2388config CMDLINE_OVERRIDE 2389 bool "Built-in command line overrides boot loader arguments" 2390 depends on CMDLINE_BOOL && CMDLINE != "" 2391 help 2392 Set this option to 'Y' to have the kernel ignore the boot loader 2393 command line, and use ONLY the built-in command line. 2394 2395 This is used to work around broken boot loaders. This should 2396 be set to 'N' under normal conditions. 2397 2398config MODIFY_LDT_SYSCALL 2399 bool "Enable the LDT (local descriptor table)" if EXPERT 2400 default y 2401 help 2402 Linux can allow user programs to install a per-process x86 2403 Local Descriptor Table (LDT) using the modify_ldt(2) system 2404 call. This is required to run 16-bit or segmented code such as 2405 DOSEMU or some Wine programs. It is also used by some very old 2406 threading libraries. 2407 2408 Enabling this feature adds a small amount of overhead to 2409 context switches and increases the low-level kernel attack 2410 surface. Disabling it removes the modify_ldt(2) system call. 2411 2412 Saying 'N' here may make sense for embedded or server kernels. 2413 2414config STRICT_SIGALTSTACK_SIZE 2415 bool "Enforce strict size checking for sigaltstack" 2416 depends on DYNAMIC_SIGFRAME 2417 help 2418 For historical reasons MINSIGSTKSZ is a constant which became 2419 already too small with AVX512 support. Add a mechanism to 2420 enforce strict checking of the sigaltstack size against the 2421 real size of the FPU frame. This option enables the check 2422 by default. It can also be controlled via the kernel command 2423 line option 'strict_sas_size' independent of this config 2424 switch. Enabling it might break existing applications which 2425 allocate a too small sigaltstack but 'work' because they 2426 never get a signal delivered. 2427 2428 Say 'N' unless you want to really enforce this check. 2429 2430source "kernel/livepatch/Kconfig" 2431 2432endmenu 2433 2434config CC_HAS_NAMED_AS 2435 def_bool CC_IS_GCC && GCC_VERSION >= 90100 2436 2437config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2438 def_bool CC_IS_GCC && GCC_VERSION >= 130300 2439 2440config USE_X86_SEG_SUPPORT 2441 def_bool y 2442 depends on CC_HAS_NAMED_AS 2443 # 2444 # -fsanitize=kernel-address (KASAN) and -fsanitize=thread 2445 # (KCSAN) are incompatible with named address spaces with 2446 # GCC < 13.3 - see GCC PR sanitizer/111736. 2447 # 2448 depends on !(KASAN || KCSAN) || CC_HAS_NAMED_AS_FIXED_SANITIZERS 2449 2450config CC_HAS_SLS 2451 def_bool $(cc-option,-mharden-sls=all) 2452 2453config CC_HAS_RETURN_THUNK 2454 def_bool $(cc-option,-mfunction-return=thunk-extern) 2455 2456config CC_HAS_ENTRY_PADDING 2457 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2458 2459config FUNCTION_PADDING_CFI 2460 int 2461 default 59 if FUNCTION_ALIGNMENT_64B 2462 default 27 if FUNCTION_ALIGNMENT_32B 2463 default 11 if FUNCTION_ALIGNMENT_16B 2464 default 3 if FUNCTION_ALIGNMENT_8B 2465 default 0 2466 2467# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2468# except Kconfig can't do arithmetic :/ 2469config FUNCTION_PADDING_BYTES 2470 int 2471 default FUNCTION_PADDING_CFI if CFI_CLANG 2472 default FUNCTION_ALIGNMENT 2473 2474config CALL_PADDING 2475 def_bool n 2476 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2477 select FUNCTION_ALIGNMENT_16B 2478 2479config FINEIBT 2480 def_bool y 2481 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE 2482 select CALL_PADDING 2483 2484config HAVE_CALL_THUNKS 2485 def_bool y 2486 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2487 2488config CALL_THUNKS 2489 def_bool n 2490 select CALL_PADDING 2491 2492config PREFIX_SYMBOLS 2493 def_bool y 2494 depends on CALL_PADDING && !CFI_CLANG 2495 2496menuconfig CPU_MITIGATIONS 2497 bool "Mitigations for CPU vulnerabilities" 2498 default y 2499 help 2500 Say Y here to enable options which enable mitigations for hardware 2501 vulnerabilities (usually related to speculative execution). 2502 Mitigations can be disabled or restricted to SMT systems at runtime 2503 via the "mitigations" kernel parameter. 2504 2505 If you say N, all mitigations will be disabled. This CANNOT be 2506 overridden at runtime. 2507 2508 Say 'Y', unless you really know what you are doing. 2509 2510if CPU_MITIGATIONS 2511 2512config MITIGATION_PAGE_TABLE_ISOLATION 2513 bool "Remove the kernel mapping in user mode" 2514 default y 2515 depends on (X86_64 || X86_PAE) 2516 help 2517 This feature reduces the number of hardware side channels by 2518 ensuring that the majority of kernel addresses are not mapped 2519 into userspace. 2520 2521 See Documentation/arch/x86/pti.rst for more details. 2522 2523config MITIGATION_RETPOLINE 2524 bool "Avoid speculative indirect branches in kernel" 2525 select OBJTOOL if HAVE_OBJTOOL 2526 default y 2527 help 2528 Compile kernel with the retpoline compiler options to guard against 2529 kernel-to-user data leaks by avoiding speculative indirect 2530 branches. Requires a compiler with -mindirect-branch=thunk-extern 2531 support for full protection. The kernel may run slower. 2532 2533config MITIGATION_RETHUNK 2534 bool "Enable return-thunks" 2535 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2536 select OBJTOOL if HAVE_OBJTOOL 2537 default y if X86_64 2538 help 2539 Compile the kernel with the return-thunks compiler option to guard 2540 against kernel-to-user data leaks by avoiding return speculation. 2541 Requires a compiler with -mfunction-return=thunk-extern 2542 support for full protection. The kernel may run slower. 2543 2544config MITIGATION_UNRET_ENTRY 2545 bool "Enable UNRET on kernel entry" 2546 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2547 default y 2548 help 2549 Compile the kernel with support for the retbleed=unret mitigation. 2550 2551config MITIGATION_CALL_DEPTH_TRACKING 2552 bool "Mitigate RSB underflow with call depth tracking" 2553 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2554 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2555 select CALL_THUNKS 2556 default y 2557 help 2558 Compile the kernel with call depth tracking to mitigate the Intel 2559 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2560 mitigation is off by default and needs to be enabled on the 2561 kernel command line via the retbleed=stuff option. For 2562 non-affected systems the overhead of this option is marginal as 2563 the call depth tracking is using run-time generated call thunks 2564 in a compiler generated padding area and call patching. This 2565 increases text size by ~5%. For non affected systems this space 2566 is unused. On affected SKL systems this results in a significant 2567 performance gain over the IBRS mitigation. 2568 2569config CALL_THUNKS_DEBUG 2570 bool "Enable call thunks and call depth tracking debugging" 2571 depends on MITIGATION_CALL_DEPTH_TRACKING 2572 select FUNCTION_ALIGNMENT_32B 2573 default n 2574 help 2575 Enable call/ret counters for imbalance detection and build in 2576 a noisy dmesg about callthunks generation and call patching for 2577 trouble shooting. The debug prints need to be enabled on the 2578 kernel command line with 'debug-callthunks'. 2579 Only enable this when you are debugging call thunks as this 2580 creates a noticeable runtime overhead. If unsure say N. 2581 2582config MITIGATION_IBPB_ENTRY 2583 bool "Enable IBPB on kernel entry" 2584 depends on CPU_SUP_AMD && X86_64 2585 default y 2586 help 2587 Compile the kernel with support for the retbleed=ibpb mitigation. 2588 2589config MITIGATION_IBRS_ENTRY 2590 bool "Enable IBRS on kernel entry" 2591 depends on CPU_SUP_INTEL && X86_64 2592 default y 2593 help 2594 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2595 This mitigates both spectre_v2 and retbleed at great cost to 2596 performance. 2597 2598config MITIGATION_SRSO 2599 bool "Mitigate speculative RAS overflow on AMD" 2600 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2601 default y 2602 help 2603 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2604 2605config MITIGATION_SLS 2606 bool "Mitigate Straight-Line-Speculation" 2607 depends on CC_HAS_SLS && X86_64 2608 select OBJTOOL if HAVE_OBJTOOL 2609 default n 2610 help 2611 Compile the kernel with straight-line-speculation options to guard 2612 against straight line speculation. The kernel image might be slightly 2613 larger. 2614 2615config MITIGATION_GDS_FORCE 2616 bool "Force GDS Mitigation" 2617 depends on CPU_SUP_INTEL 2618 default n 2619 help 2620 Gather Data Sampling (GDS) is a hardware vulnerability which allows 2621 unprivileged speculative access to data which was previously stored in 2622 vector registers. 2623 2624 This option is equivalent to setting gather_data_sampling=force on the 2625 command line. The microcode mitigation is used if present, otherwise 2626 AVX is disabled as a mitigation. On affected systems that are missing 2627 the microcode any userspace code that unconditionally uses AVX will 2628 break with this option set. 2629 2630 Setting this option on systems not vulnerable to GDS has no effect. 2631 2632 If in doubt, say N. 2633 2634config MITIGATION_RFDS 2635 bool "RFDS Mitigation" 2636 depends on CPU_SUP_INTEL 2637 default y 2638 help 2639 Enable mitigation for Register File Data Sampling (RFDS) by default. 2640 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2641 allows unprivileged speculative access to stale data previously 2642 stored in floating point, vector and integer registers. 2643 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2644 2645config MITIGATION_SPECTRE_BHI 2646 bool "Mitigate Spectre-BHB (Branch History Injection)" 2647 depends on CPU_SUP_INTEL 2648 default y 2649 help 2650 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2651 where the branch history buffer is poisoned to speculatively steer 2652 indirect branches. 2653 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2654 2655endif 2656 2657config ARCH_HAS_ADD_PAGES 2658 def_bool y 2659 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2660 2661menu "Power management and ACPI options" 2662 2663config ARCH_HIBERNATION_HEADER 2664 def_bool y 2665 depends on HIBERNATION 2666 2667source "kernel/power/Kconfig" 2668 2669source "drivers/acpi/Kconfig" 2670 2671config X86_APM_BOOT 2672 def_bool y 2673 depends on APM 2674 2675menuconfig APM 2676 tristate "APM (Advanced Power Management) BIOS support" 2677 depends on X86_32 && PM_SLEEP 2678 help 2679 APM is a BIOS specification for saving power using several different 2680 techniques. This is mostly useful for battery powered laptops with 2681 APM compliant BIOSes. If you say Y here, the system time will be 2682 reset after a RESUME operation, the /proc/apm device will provide 2683 battery status information, and user-space programs will receive 2684 notification of APM "events" (e.g. battery status change). 2685 2686 If you select "Y" here, you can disable actual use of the APM 2687 BIOS by passing the "apm=off" option to the kernel at boot time. 2688 2689 Note that the APM support is almost completely disabled for 2690 machines with more than one CPU. 2691 2692 In order to use APM, you will need supporting software. For location 2693 and more information, read <file:Documentation/power/apm-acpi.rst> 2694 and the Battery Powered Linux mini-HOWTO, available from 2695 <http://www.tldp.org/docs.html#howto>. 2696 2697 This driver does not spin down disk drives (see the hdparm(8) 2698 manpage ("man 8 hdparm") for that), and it doesn't turn off 2699 VESA-compliant "green" monitors. 2700 2701 This driver does not support the TI 4000M TravelMate and the ACER 2702 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2703 desktop machines also don't have compliant BIOSes, and this driver 2704 may cause those machines to panic during the boot phase. 2705 2706 Generally, if you don't have a battery in your machine, there isn't 2707 much point in using this driver and you should say N. If you get 2708 random kernel OOPSes or reboots that don't seem to be related to 2709 anything, try disabling/enabling this option (or disabling/enabling 2710 APM in your BIOS). 2711 2712 Some other things you should try when experiencing seemingly random, 2713 "weird" problems: 2714 2715 1) make sure that you have enough swap space and that it is 2716 enabled. 2717 2) pass the "idle=poll" option to the kernel 2718 3) switch on floating point emulation in the kernel and pass 2719 the "no387" option to the kernel 2720 4) pass the "floppy=nodma" option to the kernel 2721 5) pass the "mem=4M" option to the kernel (thereby disabling 2722 all but the first 4 MB of RAM) 2723 6) make sure that the CPU is not over clocked. 2724 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2725 8) disable the cache from your BIOS settings 2726 9) install a fan for the video card or exchange video RAM 2727 10) install a better fan for the CPU 2728 11) exchange RAM chips 2729 12) exchange the motherboard. 2730 2731 To compile this driver as a module, choose M here: the 2732 module will be called apm. 2733 2734if APM 2735 2736config APM_IGNORE_USER_SUSPEND 2737 bool "Ignore USER SUSPEND" 2738 help 2739 This option will ignore USER SUSPEND requests. On machines with a 2740 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2741 series notebooks, it is necessary to say Y because of a BIOS bug. 2742 2743config APM_DO_ENABLE 2744 bool "Enable PM at boot time" 2745 help 2746 Enable APM features at boot time. From page 36 of the APM BIOS 2747 specification: "When disabled, the APM BIOS does not automatically 2748 power manage devices, enter the Standby State, enter the Suspend 2749 State, or take power saving steps in response to CPU Idle calls." 2750 This driver will make CPU Idle calls when Linux is idle (unless this 2751 feature is turned off -- see "Do CPU IDLE calls", below). This 2752 should always save battery power, but more complicated APM features 2753 will be dependent on your BIOS implementation. You may need to turn 2754 this option off if your computer hangs at boot time when using APM 2755 support, or if it beeps continuously instead of suspending. Turn 2756 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2757 T400CDT. This is off by default since most machines do fine without 2758 this feature. 2759 2760config APM_CPU_IDLE 2761 depends on CPU_IDLE 2762 bool "Make CPU Idle calls when idle" 2763 help 2764 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2765 On some machines, this can activate improved power savings, such as 2766 a slowed CPU clock rate, when the machine is idle. These idle calls 2767 are made after the idle loop has run for some length of time (e.g., 2768 333 mS). On some machines, this will cause a hang at boot time or 2769 whenever the CPU becomes idle. (On machines with more than one CPU, 2770 this option does nothing.) 2771 2772config APM_DISPLAY_BLANK 2773 bool "Enable console blanking using APM" 2774 help 2775 Enable console blanking using the APM. Some laptops can use this to 2776 turn off the LCD backlight when the screen blanker of the Linux 2777 virtual console blanks the screen. Note that this is only used by 2778 the virtual console screen blanker, and won't turn off the backlight 2779 when using the X Window system. This also doesn't have anything to 2780 do with your VESA-compliant power-saving monitor. Further, this 2781 option doesn't work for all laptops -- it might not turn off your 2782 backlight at all, or it might print a lot of errors to the console, 2783 especially if you are using gpm. 2784 2785config APM_ALLOW_INTS 2786 bool "Allow interrupts during APM BIOS calls" 2787 help 2788 Normally we disable external interrupts while we are making calls to 2789 the APM BIOS as a measure to lessen the effects of a badly behaving 2790 BIOS implementation. The BIOS should reenable interrupts if it 2791 needs to. Unfortunately, some BIOSes do not -- especially those in 2792 many of the newer IBM Thinkpads. If you experience hangs when you 2793 suspend, try setting this to Y. Otherwise, say N. 2794 2795endif # APM 2796 2797source "drivers/cpufreq/Kconfig" 2798 2799source "drivers/cpuidle/Kconfig" 2800 2801source "drivers/idle/Kconfig" 2802 2803endmenu 2804 2805menu "Bus options (PCI etc.)" 2806 2807choice 2808 prompt "PCI access mode" 2809 depends on X86_32 && PCI 2810 default PCI_GOANY 2811 help 2812 On PCI systems, the BIOS can be used to detect the PCI devices and 2813 determine their configuration. However, some old PCI motherboards 2814 have BIOS bugs and may crash if this is done. Also, some embedded 2815 PCI-based systems don't have any BIOS at all. Linux can also try to 2816 detect the PCI hardware directly without using the BIOS. 2817 2818 With this option, you can specify how Linux should detect the 2819 PCI devices. If you choose "BIOS", the BIOS will be used, 2820 if you choose "Direct", the BIOS won't be used, and if you 2821 choose "MMConfig", then PCI Express MMCONFIG will be used. 2822 If you choose "Any", the kernel will try MMCONFIG, then the 2823 direct access method and falls back to the BIOS if that doesn't 2824 work. If unsure, go with the default, which is "Any". 2825 2826config PCI_GOBIOS 2827 bool "BIOS" 2828 2829config PCI_GOMMCONFIG 2830 bool "MMConfig" 2831 2832config PCI_GODIRECT 2833 bool "Direct" 2834 2835config PCI_GOOLPC 2836 bool "OLPC XO-1" 2837 depends on OLPC 2838 2839config PCI_GOANY 2840 bool "Any" 2841 2842endchoice 2843 2844config PCI_BIOS 2845 def_bool y 2846 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2847 2848# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2849config PCI_DIRECT 2850 def_bool y 2851 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2852 2853config PCI_MMCONFIG 2854 bool "Support mmconfig PCI config space access" if X86_64 2855 default y 2856 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2857 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2858 2859config PCI_OLPC 2860 def_bool y 2861 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2862 2863config PCI_XEN 2864 def_bool y 2865 depends on PCI && XEN 2866 2867config MMCONF_FAM10H 2868 def_bool y 2869 depends on X86_64 && PCI_MMCONFIG && ACPI 2870 2871config PCI_CNB20LE_QUIRK 2872 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2873 depends on PCI 2874 help 2875 Read the PCI windows out of the CNB20LE host bridge. This allows 2876 PCI hotplug to work on systems with the CNB20LE chipset which do 2877 not have ACPI. 2878 2879 There's no public spec for this chipset, and this functionality 2880 is known to be incomplete. 2881 2882 You should say N unless you know you need this. 2883 2884config ISA_BUS 2885 bool "ISA bus support on modern systems" if EXPERT 2886 help 2887 Expose ISA bus device drivers and options available for selection and 2888 configuration. Enable this option if your target machine has an ISA 2889 bus. ISA is an older system, displaced by PCI and newer bus 2890 architectures -- if your target machine is modern, it probably does 2891 not have an ISA bus. 2892 2893 If unsure, say N. 2894 2895# x86_64 have no ISA slots, but can have ISA-style DMA. 2896config ISA_DMA_API 2897 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2898 default y 2899 help 2900 Enables ISA-style DMA support for devices requiring such controllers. 2901 If unsure, say Y. 2902 2903if X86_32 2904 2905config ISA 2906 bool "ISA support" 2907 help 2908 Find out whether you have ISA slots on your motherboard. ISA is the 2909 name of a bus system, i.e. the way the CPU talks to the other stuff 2910 inside your box. Other bus systems are PCI, EISA, MicroChannel 2911 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2912 newer boards don't support it. If you have ISA, say Y, otherwise N. 2913 2914config SCx200 2915 tristate "NatSemi SCx200 support" 2916 help 2917 This provides basic support for National Semiconductor's 2918 (now AMD's) Geode processors. The driver probes for the 2919 PCI-IDs of several on-chip devices, so its a good dependency 2920 for other scx200_* drivers. 2921 2922 If compiled as a module, the driver is named scx200. 2923 2924config SCx200HR_TIMER 2925 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2926 depends on SCx200 2927 default y 2928 help 2929 This driver provides a clocksource built upon the on-chip 2930 27MHz high-resolution timer. Its also a workaround for 2931 NSC Geode SC-1100's buggy TSC, which loses time when the 2932 processor goes idle (as is done by the scheduler). The 2933 other workaround is idle=poll boot option. 2934 2935config OLPC 2936 bool "One Laptop Per Child support" 2937 depends on !X86_PAE 2938 select GPIOLIB 2939 select OF 2940 select OF_PROMTREE 2941 select IRQ_DOMAIN 2942 select OLPC_EC 2943 help 2944 Add support for detecting the unique features of the OLPC 2945 XO hardware. 2946 2947config OLPC_XO1_PM 2948 bool "OLPC XO-1 Power Management" 2949 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2950 help 2951 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2952 2953config OLPC_XO1_RTC 2954 bool "OLPC XO-1 Real Time Clock" 2955 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2956 help 2957 Add support for the XO-1 real time clock, which can be used as a 2958 programmable wakeup source. 2959 2960config OLPC_XO1_SCI 2961 bool "OLPC XO-1 SCI extras" 2962 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2963 depends on INPUT=y 2964 select POWER_SUPPLY 2965 help 2966 Add support for SCI-based features of the OLPC XO-1 laptop: 2967 - EC-driven system wakeups 2968 - Power button 2969 - Ebook switch 2970 - Lid switch 2971 - AC adapter status updates 2972 - Battery status updates 2973 2974config OLPC_XO15_SCI 2975 bool "OLPC XO-1.5 SCI extras" 2976 depends on OLPC && ACPI 2977 select POWER_SUPPLY 2978 help 2979 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2980 - EC-driven system wakeups 2981 - AC adapter status updates 2982 - Battery status updates 2983 2984config ALIX 2985 bool "PCEngines ALIX System Support (LED setup)" 2986 select GPIOLIB 2987 help 2988 This option enables system support for the PCEngines ALIX. 2989 At present this just sets up LEDs for GPIO control on 2990 ALIX2/3/6 boards. However, other system specific setup should 2991 get added here. 2992 2993 Note: You must still enable the drivers for GPIO and LED support 2994 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2995 2996 Note: You have to set alix.force=1 for boards with Award BIOS. 2997 2998config NET5501 2999 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3000 select GPIOLIB 3001 help 3002 This option enables system support for the Soekris Engineering net5501. 3003 3004config GEOS 3005 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3006 select GPIOLIB 3007 depends on DMI 3008 help 3009 This option enables system support for the Traverse Technologies GEOS. 3010 3011config TS5500 3012 bool "Technologic Systems TS-5500 platform support" 3013 depends on MELAN 3014 select CHECK_SIGNATURE 3015 select NEW_LEDS 3016 select LEDS_CLASS 3017 help 3018 This option enables system support for the Technologic Systems TS-5500. 3019 3020endif # X86_32 3021 3022config AMD_NB 3023 def_bool y 3024 depends on CPU_SUP_AMD && PCI 3025 3026endmenu 3027 3028menu "Binary Emulations" 3029 3030config IA32_EMULATION 3031 bool "IA32 Emulation" 3032 depends on X86_64 3033 select ARCH_WANT_OLD_COMPAT_IPC 3034 select BINFMT_ELF 3035 select COMPAT_OLD_SIGACTION 3036 help 3037 Include code to run legacy 32-bit programs under a 3038 64-bit kernel. You should likely turn this on, unless you're 3039 100% sure that you don't have any 32-bit programs left. 3040 3041config IA32_EMULATION_DEFAULT_DISABLED 3042 bool "IA32 emulation disabled by default" 3043 default n 3044 depends on IA32_EMULATION 3045 help 3046 Make IA32 emulation disabled by default. This prevents loading 32-bit 3047 processes and access to 32-bit syscalls. If unsure, leave it to its 3048 default value. 3049 3050config X86_X32_ABI 3051 bool "x32 ABI for 64-bit mode" 3052 depends on X86_64 3053 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3054 # compressed debug sections to x86_x32 properly: 3055 # https://github.com/ClangBuiltLinux/linux/issues/514 3056 # https://github.com/ClangBuiltLinux/linux/issues/1141 3057 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3058 help 3059 Include code to run binaries for the x32 native 32-bit ABI 3060 for 64-bit processors. An x32 process gets access to the 3061 full 64-bit register file and wide data path while leaving 3062 pointers at 32 bits for smaller memory footprint. 3063 3064config COMPAT_32 3065 def_bool y 3066 depends on IA32_EMULATION || X86_32 3067 select HAVE_UID16 3068 select OLD_SIGSUSPEND3 3069 3070config COMPAT 3071 def_bool y 3072 depends on IA32_EMULATION || X86_X32_ABI 3073 3074config COMPAT_FOR_U64_ALIGNMENT 3075 def_bool y 3076 depends on COMPAT 3077 3078endmenu 3079 3080config HAVE_ATOMIC_IOMAP 3081 def_bool y 3082 depends on X86_32 3083 3084source "arch/x86/kvm/Kconfig" 3085 3086source "arch/x86/Kconfig.assembler" 3087