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 HAVE_DEBUG_STACKOVERFLOW 18 select KMAP_LOCAL 19 select MODULES_USE_ELF_REL 20 select OLD_SIGACTION 21 select ARCH_SPLIT_ARG64 22 23config X86_64 24 def_bool y 25 depends on 64BIT 26 # Options that are inherently 64-bit kernel only: 27 select ARCH_HAS_GIGANTIC_PAGE 28 select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE 32 select HAVE_ARCH_SOFT_DIRTY 33 select MODULES_USE_ELF_RELA 34 select NEED_DMA_MAP_STATE 35 select SWIOTLB 36 select ARCH_HAS_ELFCORE_COMPAT 37 select ZONE_DMA32 38 select EXECMEM if DYNAMIC_FTRACE 39 select ACPI_MRRM if ACPI 40 41config FORCE_DYNAMIC_FTRACE 42 def_bool y 43 depends on X86_32 44 depends on FUNCTION_TRACER 45 select DYNAMIC_FTRACE 46 help 47 We keep the static function tracing (!DYNAMIC_FTRACE) around 48 in order to test the non static function tracing in the 49 generic code, as other architectures still use it. But we 50 only need to keep it around for x86_64. No need to keep it 51 for x86_32. For x86_32, force DYNAMIC_FTRACE. 52# 53# Arch settings 54# 55# ( Note that options that are marked 'if X86_64' could in principle be 56# ported to 32-bit as well. ) 57# 58config X86 59 def_bool y 60 # 61 # Note: keep this list sorted alphabetically 62 # 63 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 64 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 65 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 66 select ARCH_32BIT_OFF_T if X86_32 67 select ARCH_CLOCKSOURCE_INIT 68 select ARCH_CONFIGURES_CPU_MITIGATIONS 69 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 70 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 71 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 72 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 73 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 74 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 75 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 76 select ARCH_HAS_CPU_ATTACK_VECTORS if CPU_MITIGATIONS 77 select ARCH_HAS_CACHE_LINE_SIZE 78 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 79 select ARCH_HAS_CPU_FINALIZE_INIT 80 select ARCH_HAS_CPU_PASID if IOMMU_SVA 81 select ARCH_HAS_CURRENT_STACK_POINTER 82 select ARCH_HAS_DEBUG_VIRTUAL 83 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 84 select ARCH_HAS_DEVMEM_IS_ALLOWED 85 select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN 86 select ARCH_HAS_EARLY_DEBUG if KGDB 87 select ARCH_HAS_ELF_RANDOMIZE 88 select ARCH_HAS_EXECMEM_ROX if X86_64 && STRICT_MODULE_RWX 89 select ARCH_HAS_FAST_MULTIPLIER 90 select ARCH_HAS_FORTIFY_SOURCE 91 select ARCH_HAS_GCOV_PROFILE_ALL 92 select ARCH_HAS_KCOV if X86_64 93 select ARCH_HAS_KERNEL_FPU_SUPPORT 94 select ARCH_HAS_MEM_ENCRYPT 95 select ARCH_HAS_MEMBARRIER_SYNC_CORE 96 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 97 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 98 select ARCH_HAS_PMEM_API if X86_64 99 select ARCH_HAS_PREEMPT_LAZY 100 select ARCH_HAS_PTDUMP 101 select ARCH_HAS_PTE_SPECIAL 102 select ARCH_HAS_HW_PTE_YOUNG 103 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 104 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 105 select ARCH_HAS_COPY_MC if X86_64 106 select ARCH_HAS_SET_MEMORY 107 select ARCH_HAS_SET_DIRECT_MAP 108 select ARCH_HAS_STRICT_KERNEL_RWX 109 select ARCH_HAS_STRICT_MODULE_RWX 110 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 111 select ARCH_HAS_SYSCALL_WRAPPER 112 select ARCH_HAS_UBSAN 113 select ARCH_HAS_DEBUG_WX 114 select ARCH_HAS_ZONE_DMA_SET if EXPERT 115 select ARCH_HAVE_NMI_SAFE_CMPXCHG 116 select ARCH_HAVE_EXTRA_ELF_NOTES 117 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 118 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 119 select ARCH_MIGHT_HAVE_PC_PARPORT 120 select ARCH_MIGHT_HAVE_PC_SERIO 121 select ARCH_STACKWALK 122 select ARCH_SUPPORTS_ACPI 123 select ARCH_SUPPORTS_ATOMIC_RMW 124 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 125 select ARCH_SUPPORTS_HUGETLBFS 126 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 127 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 128 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 129 select ARCH_SUPPORTS_CFI if X86_64 130 select ARCH_USES_CFI_TRAPS if X86_64 && CFI 131 select ARCH_SUPPORTS_LTO_CLANG 132 select ARCH_SUPPORTS_LTO_CLANG_THIN 133 select ARCH_SUPPORTS_RT 134 select ARCH_SUPPORTS_AUTOFDO_CLANG 135 select ARCH_SUPPORTS_PROPELLER_CLANG if X86_64 136 select ARCH_USE_BUILTIN_BSWAP 137 select ARCH_USE_CMPXCHG_LOCKREF if X86_CX8 138 select ARCH_USE_MEMTEST 139 select ARCH_USE_QUEUED_RWLOCKS 140 select ARCH_USE_QUEUED_SPINLOCKS 141 select ARCH_USE_SYM_ANNOTATIONS 142 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 143 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 144 select ARCH_WANTS_CLOCKSOURCE_READ_INLINE if X86_64 145 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 146 select ARCH_WANTS_NO_INSTR 147 select ARCH_WANT_GENERAL_HUGETLB 148 select ARCH_WANT_HUGE_PMD_SHARE if X86_64 149 select ARCH_WANT_LD_ORPHAN_WARN 150 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 151 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 152 select ARCH_WANT_HUGETLB_VMEMMAP_PREINIT if X86_64 153 select ARCH_WANTS_THP_SWAP if X86_64 154 select ARCH_HAS_PARANOID_L1D_FLUSH 155 select ARCH_WANT_IRQS_OFF_ACTIVATE_MM 156 select BUILDTIME_TABLE_SORT 157 select CLKEVT_I8253 158 select CLOCKSOURCE_WATCHDOG 159 # Word-size accesses may read uninitialized data past the trailing \0 160 # in strings and cause false KMSAN reports. 161 select DCACHE_WORD_ACCESS if !KMSAN 162 select DYNAMIC_SIGFRAME 163 select EDAC_ATOMIC_SCRUB 164 select EDAC_SUPPORT 165 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 166 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 167 select GENERIC_CLOCKEVENTS_COUPLED_INLINE if X86_64 168 select GENERIC_CLOCKEVENTS_MIN_ADJUST 169 select GENERIC_CMOS_UPDATE 170 select GENERIC_CPU_AUTOPROBE 171 select GENERIC_CPU_DEVICES 172 select GENERIC_CPU_VULNERABILITIES 173 select GENERIC_EARLY_IOREMAP 174 select GENERIC_ENTRY 175 select GENERIC_IOMAP 176 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 177 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 178 select GENERIC_IRQ_MIGRATION if SMP 179 select GENERIC_IRQ_PROBE 180 select GENERIC_IRQ_RESERVATION_MODE 181 select GENERIC_IRQ_SHOW 182 select GENERIC_PENDING_IRQ if SMP 183 select GENERIC_SMP_IDLE_THREAD 184 select GENERIC_TIME_VSYSCALL 185 select GENERIC_GETTIMEOFDAY 186 select GENERIC_VDSO_OVERFLOW_PROTECT 187 select GUP_GET_PXX_LOW_HIGH if X86_PAE 188 select HARDIRQS_SW_RESEND 189 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 190 select HAS_IOPORT 191 select HAVE_ACPI_APEI if ACPI 192 select HAVE_ACPI_APEI_NMI if ACPI 193 select HAVE_ALIGNED_STRUCT_PAGE 194 select HAVE_ARCH_AUDITSYSCALL 195 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 196 select HAVE_ARCH_HUGE_VMALLOC if X86_64 197 select HAVE_ARCH_JUMP_LABEL 198 select HAVE_ARCH_JUMP_LABEL_RELATIVE 199 select HAVE_ARCH_KASAN if X86_64 200 select HAVE_ARCH_KASAN_VMALLOC if X86_64 201 select HAVE_ARCH_KFENCE 202 select HAVE_ARCH_KMSAN if X86_64 203 select HAVE_ARCH_KGDB 204 select HAVE_ARCH_KSTACK_ERASE 205 select HAVE_ARCH_MMAP_RND_BITS if MMU 206 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 207 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 208 select HAVE_ARCH_PREL32_RELOCATIONS 209 select HAVE_ARCH_SECCOMP_FILTER 210 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 211 select HAVE_ARCH_TRACEHOOK 212 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 213 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 214 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 215 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 216 select HAVE_ARCH_VMAP_STACK if X86_64 217 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 218 select HAVE_ARCH_WITHIN_STACK_FRAMES 219 select HAVE_ASM_MODVERSIONS 220 select HAVE_CMPXCHG_DOUBLE 221 select HAVE_CMPXCHG_LOCAL 222 select HAVE_CONTEXT_TRACKING_USER if X86_64 223 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 224 select HAVE_C_RECORDMCOUNT 225 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 226 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 227 select HAVE_BUILDTIME_MCOUNT_SORT 228 select HAVE_DEBUG_KMEMLEAK 229 select HAVE_DMA_CONTIGUOUS 230 select HAVE_DYNAMIC_FTRACE 231 select HAVE_DYNAMIC_FTRACE_WITH_REGS 232 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 233 select HAVE_FTRACE_REGS_HAVING_PT_REGS if X86_64 234 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 235 select HAVE_DYNAMIC_FTRACE_WITH_JMP if X86_64 236 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 237 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 238 select HAVE_EBPF_JIT 239 select HAVE_EFFICIENT_UNALIGNED_ACCESS 240 select HAVE_EISA if X86_32 241 select HAVE_EXIT_THREAD 242 select HAVE_GENERIC_TIF_BITS 243 select HAVE_GUP_FAST 244 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 245 select HAVE_FTRACE_GRAPH_FUNC if HAVE_FUNCTION_GRAPH_TRACER 246 select HAVE_FUNCTION_GRAPH_FREGS if HAVE_FUNCTION_GRAPH_TRACER 247 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 248 select HAVE_FUNCTION_TRACER 249 select HAVE_GCC_PLUGINS 250 select HAVE_HW_BREAKPOINT 251 select HAVE_IOREMAP_PROT 252 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 253 select HAVE_IRQ_TIME_ACCOUNTING 254 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 255 select HAVE_KERNEL_BZIP2 256 select HAVE_KERNEL_GZIP 257 select HAVE_KERNEL_LZ4 258 select HAVE_KERNEL_LZMA 259 select HAVE_KERNEL_LZO 260 select HAVE_KERNEL_XZ 261 select HAVE_KERNEL_ZSTD 262 select HAVE_KPROBES 263 select HAVE_KPROBES_ON_FTRACE 264 select HAVE_FUNCTION_ERROR_INJECTION 265 select HAVE_KRETPROBES 266 select HAVE_RETHOOK 267 select HAVE_KLP_BUILD if X86_64 268 select HAVE_LIVEPATCH if X86_64 269 select HAVE_MIXED_BREAKPOINTS_REGS 270 select HAVE_MOD_ARCH_SPECIFIC 271 select HAVE_MOVE_PMD 272 select HAVE_MOVE_PUD 273 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 274 select HAVE_NMI 275 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 276 select HAVE_OBJTOOL if X86_64 277 select HAVE_OPTPROBES 278 select HAVE_PAGE_SIZE_4KB 279 select HAVE_PCSPKR_PLATFORM 280 select HAVE_PERF_EVENTS 281 select HAVE_PERF_EVENTS_NMI 282 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 283 select HAVE_PCI 284 select HAVE_PERF_REGS 285 select HAVE_PERF_USER_STACK_DUMP 286 select ASYNC_KERNEL_PGTABLE_FREE if IOMMU_SVA 287 select MMU_GATHER_RCU_TABLE_FREE 288 select MMU_GATHER_MERGE_VMAS 289 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 290 select HAVE_REGS_AND_STACK_ACCESS_API 291 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 292 select HAVE_FUNCTION_ARG_ACCESS_API 293 select HAVE_SETUP_PER_CPU_AREA 294 select HAVE_SOFTIRQ_ON_OWN_STACK 295 select HAVE_STACKPROTECTOR 296 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 297 select HAVE_STATIC_CALL 298 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 299 select HAVE_PREEMPT_DYNAMIC_CALL 300 select HAVE_RSEQ 301 select HAVE_RUST if X86_64 302 select HAVE_SYSCALL_TRACEPOINTS 303 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 304 select HAVE_UNSTABLE_SCHED_CLOCK 305 select HAVE_UNWIND_USER_FP if X86_64 306 select HAVE_USER_RETURN_NOTIFIER 307 select HAVE_GENERIC_VDSO 308 select VDSO_GETRANDOM if X86_64 309 select HOTPLUG_PARALLEL if SMP && X86_64 310 select HOTPLUG_SMT if SMP 311 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 312 select IRQ_FORCED_THREADING 313 select LOCK_MM_AND_FIND_VMA 314 select NEED_PER_CPU_EMBED_FIRST_CHUNK 315 select NEED_PER_CPU_PAGE_FIRST_CHUNK 316 select NEED_SG_DMA_LENGTH 317 select NUMA_MEMBLKS if NUMA 318 select PCI_DOMAINS if PCI 319 select PCI_LOCKLESS_CONFIG if PCI 320 select PERF_EVENTS 321 select RTC_LIB 322 select RTC_MC146818_LIB 323 select SPARSE_IRQ 324 select SYSCTL_EXCEPTION_TRACE 325 select THREAD_INFO_IN_TASK 326 select TRACE_IRQFLAGS_SUPPORT 327 select TRACE_IRQFLAGS_NMI_SUPPORT 328 select USER_STACKTRACE_SUPPORT 329 select HAVE_ARCH_KCSAN if X86_64 330 select PROC_PID_ARCH_STATUS if PROC_FS 331 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 332 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 333 select FUNCTION_ALIGNMENT_4B 334 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 335 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 336 select ARCH_SUPPORTS_SCHED_SMT if SMP 337 select SCHED_SMT if SMP 338 select ARCH_SUPPORTS_SCHED_CLUSTER if SMP 339 select ARCH_SUPPORTS_SCHED_MC if SMP 340 select HAVE_SINGLE_FTRACE_DIRECT_OPS if X86_64 && DYNAMIC_FTRACE_WITH_DIRECT_CALLS 341 342config INSTRUCTION_DECODER 343 def_bool y 344 depends on KPROBES || PERF_EVENTS || UPROBES 345 346config OUTPUT_FORMAT 347 string 348 default "elf32-i386" if X86_32 349 default "elf64-x86-64" if X86_64 350 351config LOCKDEP_SUPPORT 352 def_bool y 353 354config STACKTRACE_SUPPORT 355 def_bool y 356 357config MMU 358 def_bool y 359 360config ARCH_MMAP_RND_BITS_MIN 361 default 28 if 64BIT 362 default 8 363 364config ARCH_MMAP_RND_BITS_MAX 365 default 32 if 64BIT 366 default 16 367 368config ARCH_MMAP_RND_COMPAT_BITS_MIN 369 default 8 370 371config ARCH_MMAP_RND_COMPAT_BITS_MAX 372 default 16 373 374config SBUS 375 bool 376 377config GENERIC_ISA_DMA 378 def_bool y 379 depends on ISA_DMA_API 380 381config GENERIC_CSUM 382 bool 383 default y if KMSAN || KASAN 384 385config GENERIC_BUG 386 def_bool y 387 depends on BUG 388 select GENERIC_BUG_RELATIVE_POINTERS 389 390config GENERIC_BUG_RELATIVE_POINTERS 391 bool 392 393config ARCH_MAY_HAVE_PC_FDC 394 def_bool y 395 depends on ISA_DMA_API 396 397config GENERIC_CALIBRATE_DELAY 398 def_bool y 399 400config ARCH_HAS_CPU_RELAX 401 def_bool y 402 403config ARCH_HIBERNATION_POSSIBLE 404 def_bool y 405 406config ARCH_SUSPEND_POSSIBLE 407 def_bool y 408 409config AUDIT_ARCH 410 def_bool y if X86_64 411 412config KASAN_SHADOW_OFFSET 413 hex 414 depends on KASAN 415 default 0xdffffc0000000000 416 417config HAVE_INTEL_TXT 418 def_bool y 419 depends on INTEL_IOMMU && ACPI 420 421config ARCH_SUPPORTS_UPROBES 422 def_bool y 423 424config FIX_EARLYCON_MEM 425 def_bool y 426 427config DYNAMIC_PHYSICAL_MASK 428 bool 429 430config PGTABLE_LEVELS 431 int 432 default 5 if X86_64 433 default 3 if X86_PAE 434 default 2 435 436menu "Processor type and features" 437 438config SMP 439 bool "Symmetric multi-processing support" 440 help 441 This enables support for systems with more than one CPU. If you have 442 a system with only one CPU, say N. If you have a system with more 443 than one CPU, say Y. 444 445 If you say N here, the kernel will run on uni- and multiprocessor 446 machines, but will use only one CPU of a multiprocessor machine. If 447 you say Y here, the kernel will run on many, but not all, 448 uniprocessor machines. On a uniprocessor machine, the kernel 449 will run faster if you say N here. 450 451 People using multiprocessor machines who say Y here should also say 452 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 453 Management" code will be disabled if you say Y here. 454 455 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 456 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 457 <http://www.tldp.org/docs.html#howto>. 458 459 If you don't know what to do here, say N. 460 461config X86_X2APIC 462 bool "x2APIC interrupt controller architecture support" 463 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 464 default y 465 help 466 x2APIC is an interrupt controller architecture, a component of which 467 (the local APIC) is present in the CPU. It allows faster access to 468 the local APIC and supports a larger number of CPUs in the system 469 than the predecessors. 470 471 x2APIC was introduced in Intel CPUs around 2008 and in AMD EPYC CPUs 472 in 2019, but it can be disabled by the BIOS. It is also frequently 473 emulated in virtual machines, even when the host CPU does not support 474 it. Support in the CPU can be checked by executing 475 grep x2apic /proc/cpuinfo 476 477 If this configuration option is disabled, the kernel will boot with 478 very reduced functionality and performance on some platforms that 479 have x2APIC enabled. On the other hand, on hardware that does not 480 support x2APIC, a kernel with this option enabled will just fallback 481 to older APIC implementations. 482 483 If in doubt, say Y. 484 485config AMD_SECURE_AVIC 486 bool "AMD Secure AVIC" 487 depends on AMD_MEM_ENCRYPT && X86_X2APIC 488 help 489 Enable this to get AMD Secure AVIC support on guests that have this feature. 490 491 AMD Secure AVIC provides hardware acceleration for performance sensitive 492 APIC accesses and support for managing guest owned APIC state for SEV-SNP 493 guests. Secure AVIC does not support xAPIC mode. It has functional 494 dependency on x2apic being enabled in the guest. 495 496 If you don't know what to do here, say N. 497 498config X86_POSTED_MSI 499 bool "Enable MSI and MSI-x delivery by posted interrupts" 500 depends on X86_64 && IRQ_REMAP 501 help 502 This enables MSIs that are under interrupt remapping to be delivered as 503 posted interrupts to the host kernel. Interrupt throughput can 504 potentially be improved by coalescing CPU notifications during high 505 frequency bursts. 506 507 If you don't know what to do here, say N. 508 509config X86_MPPARSE 510 bool "Enable MPS table" if ACPI 511 default y 512 depends on X86_LOCAL_APIC 513 help 514 For old smp systems that do not have proper acpi support. Newer systems 515 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 516 517config X86_CPU_RESCTRL 518 bool "x86 CPU resource control support" 519 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 520 depends on MISC_FILESYSTEMS 521 select ARCH_HAS_CPU_RESCTRL 522 select RESCTRL_FS 523 select RESCTRL_FS_PSEUDO_LOCK 524 help 525 Enable x86 CPU resource control support. 526 527 Provide support for the allocation and monitoring of system resources 528 usage by the CPU. 529 530 Intel calls this Intel Resource Director Technology 531 (Intel(R) RDT). More information about RDT can be found in the 532 Intel x86 Architecture Software Developer Manual. 533 534 AMD calls this AMD Platform Quality of Service (AMD QoS). 535 More information about AMD QoS can be found in the AMD64 Technology 536 Platform Quality of Service Extensions manual. 537 538 Say N if unsure. 539 540config X86_CPU_RESCTRL_INTEL_AET 541 bool "Intel Application Energy Telemetry" 542 depends on X86_64 && X86_CPU_RESCTRL && CPU_SUP_INTEL && INTEL_PMT_TELEMETRY=y && INTEL_TPMI=y 543 help 544 Enable per-RMID telemetry events in resctrl. 545 546 Intel feature that collects per-RMID execution data 547 about energy consumption, measure of frequency independent 548 activity and other performance metrics. Data is aggregated 549 per package. 550 551 Say N if unsure. 552 553config X86_FRED 554 bool "Flexible Return and Event Delivery" 555 depends on X86_64 556 help 557 When enabled, use Flexible Return and Event Delivery 558 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 559 ring transitions and exception/interrupt handling if the 560 system supports it. 561 562config X86_EXTENDED_PLATFORM 563 bool "Support for extended (non-PC) x86 platforms" 564 default y 565 help 566 If you disable this option then the kernel will only support 567 standard PC platforms. (which covers the vast majority of 568 systems out there.) 569 570 If you enable this option then you'll be able to select support 571 for the following non-PC x86 platforms, depending on the value of 572 CONFIG_64BIT. 573 574 32-bit platforms (CONFIG_64BIT=n): 575 Goldfish (mostly Android emulator) 576 Intel CE media processor (CE4100) SoC 577 Intel Quark 578 RDC R-321x SoC 579 580 64-bit platforms (CONFIG_64BIT=y): 581 Numascale NumaChip 582 ScaleMP vSMP 583 SGI Ultraviolet 584 Merrifield/Moorefield MID devices 585 Goldfish (mostly Android emulator) 586 587 If you have one of these systems, or if you want to build a 588 generic distribution kernel, say Y here - otherwise say N. 589 590# This is an alphabetically sorted list of 64 bit extended platforms 591# Please maintain the alphabetic order if and when there are additions 592config X86_NUMACHIP 593 bool "Numascale NumaChip" 594 depends on X86_64 595 depends on X86_EXTENDED_PLATFORM 596 depends on NUMA 597 depends on SMP 598 depends on X86_X2APIC 599 depends on PCI_MMCONFIG 600 help 601 Adds support for Numascale NumaChip large-SMP systems. Needed to 602 enable more than ~168 cores. 603 If you don't have one of these, you should say N here. 604 605config X86_VSMP 606 bool "ScaleMP vSMP" 607 select HYPERVISOR_GUEST 608 select PARAVIRT 609 depends on X86_64 && PCI 610 depends on X86_EXTENDED_PLATFORM 611 depends on SMP 612 help 613 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 614 supposed to run on these EM64T-based machines. Only choose this option 615 if you have one of these machines. 616 617config X86_UV 618 bool "SGI Ultraviolet" 619 depends on X86_64 620 depends on X86_EXTENDED_PLATFORM 621 depends on NUMA 622 depends on EFI 623 depends on KEXEC_CORE 624 depends on X86_X2APIC 625 depends on PCI 626 help 627 This option is needed in order to support SGI Ultraviolet systems. 628 If you don't have one of these, you should say N here. 629 630config X86_INTEL_MID 631 bool "Intel Z34xx/Z35xx MID platform support" 632 depends on X86_EXTENDED_PLATFORM 633 depends on X86_PLATFORM_DEVICES 634 depends on PCI 635 depends on X86_64 || (EXPERT && PCI_GOANY) 636 depends on X86_IO_APIC 637 select I2C 638 select DW_APB_TIMER 639 select INTEL_SCU_PCI 640 help 641 Select to build a kernel capable of supporting 64-bit Intel MID 642 (Mobile Internet Device) platform systems which do not have 643 the PCI legacy interfaces. 644 645 The only supported devices are the 22nm Merrified (Z34xx) 646 and Moorefield (Z35xx) SoC used in the Intel Edison board and 647 a small number of Android devices such as the Asus Zenfone 2, 648 Asus FonePad 8 and Dell Venue 7. 649 650 If you are building for a PC class system or non-MID tablet 651 SoCs like Bay Trail (Z36xx/Z37xx), say N here. 652 653 Intel MID platforms are based on an Intel processor and chipset which 654 consume less power than most of the x86 derivatives. 655 656config X86_GOLDFISH 657 bool "Goldfish (Virtual Platform)" 658 depends on X86_EXTENDED_PLATFORM 659 help 660 Enable support for the Goldfish virtual platform used primarily 661 for Android development. Unless you are building for the Android 662 Goldfish emulator say N here. 663 664# Following is an alphabetically sorted list of 32 bit extended platforms 665# Please maintain the alphabetic order if and when there are additions 666 667config X86_INTEL_CE 668 bool "CE4100 TV platform" 669 depends on PCI 670 depends on PCI_GODIRECT 671 depends on X86_IO_APIC 672 depends on X86_32 673 depends on X86_EXTENDED_PLATFORM 674 select X86_REBOOTFIXUPS 675 select OF 676 select OF_EARLY_FLATTREE 677 help 678 Select for the Intel CE media processor (CE4100) SOC. 679 This option compiles in support for the CE4100 SOC for settop 680 boxes and media devices. 681 682config X86_INTEL_QUARK 683 bool "Intel Quark platform support" 684 depends on X86_32 685 depends on X86_EXTENDED_PLATFORM 686 depends on X86_PLATFORM_DEVICES 687 depends on X86_TSC 688 depends on PCI 689 depends on PCI_GOANY 690 depends on X86_IO_APIC 691 select IOSF_MBI 692 select INTEL_IMR 693 select COMMON_CLK 694 help 695 Select to include support for Quark X1000 SoC. 696 Say Y here if you have a Quark based system such as the Arduino 697 compatible Intel Galileo. 698 699config X86_RDC321X 700 bool "RDC R-321x SoC" 701 depends on X86_32 702 depends on X86_EXTENDED_PLATFORM 703 select M486 704 select X86_REBOOTFIXUPS 705 help 706 This option is needed for RDC R-321x system-on-chip, also known 707 as R-8610-(G). 708 If you don't have one of these chips, you should say N here. 709 710config X86_INTEL_LPSS 711 bool "Intel Low Power Subsystem Support" 712 depends on X86 && ACPI && PCI 713 select COMMON_CLK 714 select PINCTRL 715 select IOSF_MBI 716 help 717 Select to build support for Intel Low Power Subsystem such as 718 found on Intel Lynxpoint PCH. Selecting this option enables 719 things like clock tree (common clock framework) and pincontrol 720 which are needed by the LPSS peripheral drivers. 721 722config X86_AMD_PLATFORM_DEVICE 723 bool "AMD ACPI2Platform devices support" 724 depends on ACPI 725 select COMMON_CLK 726 select PINCTRL 727 help 728 Select to interpret AMD specific ACPI device to platform device 729 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 730 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 731 implemented under PINCTRL subsystem. 732 733config IOSF_MBI 734 tristate "Intel SoC IOSF Sideband support for SoC platforms" 735 depends on PCI 736 help 737 This option enables sideband register access support for Intel SoC 738 platforms. On these platforms the IOSF sideband is used in lieu of 739 MSR's for some register accesses, mostly but not limited to thermal 740 and power. Drivers may query the availability of this device to 741 determine if they need the sideband in order to work on these 742 platforms. The sideband is available on the following SoC products. 743 This list is not meant to be exclusive. 744 - BayTrail 745 - Braswell 746 - Quark 747 748 You should say Y if you are running a kernel on one of these SoC's. 749 750config IOSF_MBI_DEBUG 751 bool "Enable IOSF sideband access through debugfs" 752 depends on IOSF_MBI && DEBUG_FS 753 help 754 Select this option to expose the IOSF sideband access registers (MCR, 755 MDR, MCRX) through debugfs to write and read register information from 756 different units on the SoC. This is most useful for obtaining device 757 state information for debug and analysis. As this is a general access 758 mechanism, users of this option would have specific knowledge of the 759 device they want to access. 760 761 If you don't require the option or are in doubt, say N. 762 763config X86_SUPPORTS_MEMORY_FAILURE 764 def_bool y 765 # MCE code calls memory_failure(): 766 depends on X86_MCE 767 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 768 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 769 depends on X86_64 || !SPARSEMEM 770 select ARCH_SUPPORTS_MEMORY_FAILURE 771 772config X86_32_IRIS 773 tristate "Eurobraille/Iris poweroff module" 774 depends on X86_32 775 help 776 The Iris machines from EuroBraille do not have APM or ACPI support 777 to shut themselves down properly. A special I/O sequence is 778 needed to do so, which is what this module does at 779 kernel shutdown. 780 781 This is only for Iris machines from EuroBraille. 782 783 If unused, say N. 784 785config SCHED_OMIT_FRAME_POINTER 786 def_bool y 787 prompt "Single-depth WCHAN output" 788 depends on X86 789 help 790 Calculate simpler /proc/<PID>/wchan values. If this option 791 is disabled then wchan values will recurse back to the 792 caller function. This provides more accurate wchan values, 793 at the expense of slightly more scheduling overhead. 794 795 If in doubt, say "Y". 796 797menuconfig HYPERVISOR_GUEST 798 bool "Linux guest support" 799 help 800 Say Y here to enable options for running Linux under various hyper- 801 visors. This option enables basic hypervisor detection and platform 802 setup. 803 804 If you say N, all options in this submenu will be skipped and 805 disabled, and Linux guest support won't be built in. 806 807if HYPERVISOR_GUEST 808 809config PARAVIRT 810 bool "Enable paravirtualization code" 811 depends on HAVE_STATIC_CALL 812 select HAVE_PV_STEAL_CLOCK_GEN 813 help 814 This changes the kernel so it can modify itself when it is run 815 under a hypervisor, potentially improving performance significantly 816 over full virtualization. However, when run without a hypervisor 817 the kernel is theoretically slower and slightly larger. 818 819config PARAVIRT_XXL 820 bool 821 depends on X86_64 822 select ARCH_HAS_LAZY_MMU_MODE 823 824config PARAVIRT_SPINLOCKS 825 bool "Paravirtualization layer for spinlocks" 826 depends on PARAVIRT && SMP 827 help 828 Paravirtualized spinlocks allow a pvops backend to replace the 829 spinlock implementation with something virtualization-friendly 830 (for example, block the virtual CPU rather than spinning). 831 832 It has a minimal impact on native kernels and gives a nice performance 833 benefit on paravirtualized KVM / Xen kernels. 834 835 If you are unsure how to answer this question, answer Y. 836 837config X86_HV_CALLBACK_VECTOR 838 def_bool n 839 840source "arch/x86/xen/Kconfig" 841 842config KVM_GUEST 843 bool "KVM Guest support (including kvmclock)" 844 depends on PARAVIRT 845 select PARAVIRT_CLOCK 846 select ARCH_CPUIDLE_HALTPOLL 847 select X86_HV_CALLBACK_VECTOR 848 default y 849 help 850 This option enables various optimizations for running under the KVM 851 hypervisor. It includes a paravirtualized clock, so that instead 852 of relying on a PIT (or probably other) emulation by the 853 underlying device model, the host provides the guest with 854 timing infrastructure such as time of day, and system time 855 856config ARCH_CPUIDLE_HALTPOLL 857 def_bool n 858 prompt "Disable host haltpoll when loading haltpoll driver" 859 help 860 If virtualized under KVM, disable host haltpoll. 861 862config PVH 863 bool "Support for running PVH guests" 864 help 865 This option enables the PVH entry point for guest virtual machines 866 as specified in the x86/HVM direct boot ABI. 867 868config PARAVIRT_TIME_ACCOUNTING 869 bool "Paravirtual steal time accounting" 870 depends on PARAVIRT 871 help 872 Select this option to enable fine granularity task steal time 873 accounting. Time spent executing other tasks in parallel with 874 the current vCPU is discounted from the vCPU power. To account for 875 that, there can be a small performance impact. 876 877 If in doubt, say N here. 878 879config PARAVIRT_CLOCK 880 bool 881 882config JAILHOUSE_GUEST 883 bool "Jailhouse non-root cell support" 884 depends on X86_64 && PCI 885 select X86_PM_TIMER 886 help 887 This option allows to run Linux as guest in a Jailhouse non-root 888 cell. You can leave this option disabled if you only want to start 889 Jailhouse and run Linux afterwards in the root cell. 890 891config ACRN_GUEST 892 bool "ACRN Guest support" 893 depends on X86_64 894 select X86_HV_CALLBACK_VECTOR 895 help 896 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 897 a flexible, lightweight reference open-source hypervisor, built with 898 real-time and safety-criticality in mind. It is built for embedded 899 IOT with small footprint and real-time features. More details can be 900 found in https://projectacrn.org/. 901 902config BHYVE_GUEST 903 bool "Bhyve (BSD Hypervisor) Guest support" 904 depends on X86_64 905 help 906 This option allows to run Linux to recognise when it is running as a 907 guest in the Bhyve hypervisor, and to support more than 255 vCPUs when 908 when doing so. More details about Bhyve can be found at https://bhyve.org 909 and https://wiki.freebsd.org/bhyve/. 910 911config INTEL_TDX_GUEST 912 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 913 depends on X86_64 && CPU_SUP_INTEL 914 depends on X86_X2APIC 915 depends on EFI_STUB 916 depends on PARAVIRT 917 select ARCH_HAS_CC_PLATFORM 918 select X86_MEM_ENCRYPT 919 select X86_MCE 920 select UNACCEPTED_MEMORY 921 help 922 Support running as a guest under Intel TDX. Without this support, 923 the guest kernel can not boot or run under TDX. 924 TDX includes memory encryption and integrity capabilities 925 which protect the confidentiality and integrity of guest 926 memory contents and CPU state. TDX guests are protected from 927 some attacks from the VMM. 928 929endif # HYPERVISOR_GUEST 930 931source "arch/x86/Kconfig.cpu" 932 933config HPET_TIMER 934 def_bool X86_64 935 prompt "HPET Timer Support" if X86_32 936 help 937 Use the IA-PC HPET (High Precision Event Timer) to manage 938 time in preference to the PIT and RTC, if a HPET is 939 present. 940 HPET is the next generation timer replacing legacy 8254s. 941 The HPET provides a stable time base on SMP 942 systems, unlike the TSC, but it is more expensive to access, 943 as it is off-chip. The interface used is documented 944 in the HPET spec, revision 1. 945 946 You can safely choose Y here. However, HPET will only be 947 activated if the platform and the BIOS support this feature. 948 Otherwise the 8254 will be used for timing services. 949 950 Choose N to continue using the legacy 8254 timer. 951 952config HPET_EMULATE_RTC 953 def_bool y 954 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 955 956# Mark as expert because too many people got it wrong. 957# The code disables itself when not needed. 958config DMI 959 default y 960 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 961 bool "Enable DMI scanning" if EXPERT 962 help 963 Enabled scanning of DMI to identify machine quirks. Say Y 964 here unless you have verified that your setup is not 965 affected by entries in the DMI blacklist. Required by PNP 966 BIOS code. 967 968config GART_IOMMU 969 bool "Old AMD GART IOMMU support" 970 select IOMMU_HELPER 971 select SWIOTLB 972 depends on X86_64 && PCI && AMD_NB 973 help 974 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 975 GART based hardware IOMMUs. 976 977 The GART supports full DMA access for devices with 32-bit access 978 limitations, on systems with more than 3 GB. This is usually needed 979 for USB, sound, many IDE/SATA chipsets and some other devices. 980 981 Newer systems typically have a modern AMD IOMMU, supported via 982 the CONFIG_AMD_IOMMU=y config option. 983 984 In normal configurations this driver is only active when needed: 985 there's more than 3 GB of memory and the system contains a 986 32-bit limited device. 987 988 If unsure, say Y. 989 990config BOOT_VESA_SUPPORT 991 bool 992 help 993 If true, at least one selected framebuffer driver can take advantage 994 of VESA video modes set at an early boot stage via the vga= parameter. 995 996config MAXSMP 997 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 998 depends on X86_64 && SMP && DEBUG_KERNEL 999 select CPUMASK_OFFSTACK 1000 help 1001 Enable maximum number of CPUS and NUMA Nodes for this architecture. 1002 If unsure, say N. 1003 1004# 1005# The maximum number of CPUs supported: 1006# 1007# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 1008# and which can be configured interactively in the 1009# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 1010# 1011# The ranges are different on 32-bit and 64-bit kernels, depending on 1012# hardware capabilities and scalability features of the kernel. 1013# 1014# ( If MAXSMP is enabled we just use the highest possible value and disable 1015# interactive configuration. ) 1016# 1017 1018config NR_CPUS_RANGE_BEGIN 1019 int 1020 default NR_CPUS_RANGE_END if MAXSMP 1021 default 1 if !SMP 1022 default 2 1023 1024config NR_CPUS_RANGE_END 1025 int 1026 depends on X86_32 1027 default 8 if SMP 1028 default 1 if !SMP 1029 1030config NR_CPUS_RANGE_END 1031 int 1032 depends on X86_64 1033 default 8192 if SMP && CPUMASK_OFFSTACK 1034 default 512 if SMP && !CPUMASK_OFFSTACK 1035 default 1 if !SMP 1036 1037config NR_CPUS_DEFAULT 1038 int 1039 depends on X86_32 1040 default 8 if SMP 1041 default 1 if !SMP 1042 1043config NR_CPUS_DEFAULT 1044 int 1045 depends on X86_64 1046 default 8192 if MAXSMP 1047 default 64 if SMP 1048 default 1 if !SMP 1049 1050config NR_CPUS 1051 int "Maximum number of CPUs" if SMP && !MAXSMP 1052 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1053 default NR_CPUS_DEFAULT 1054 help 1055 This allows you to specify the maximum number of CPUs which this 1056 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1057 supported value is 8192, otherwise the maximum value is 512. The 1058 minimum value which makes sense is 2. 1059 1060 This is purely to save memory: each supported CPU adds about 8KB 1061 to the kernel image. 1062 1063config SCHED_MC_PRIO 1064 bool "CPU core priorities scheduler support" 1065 depends on SCHED_MC 1066 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1067 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1068 select CPU_FREQ 1069 default y 1070 help 1071 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1072 core ordering determined at manufacturing time, which allows 1073 certain cores to reach higher turbo frequencies (when running 1074 single threaded workloads) than others. 1075 1076 Enabling this kernel feature teaches the scheduler about 1077 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1078 scheduler's CPU selection logic accordingly, so that higher 1079 overall system performance can be achieved. 1080 1081 This feature will have no effect on CPUs without this feature. 1082 1083 If unsure say Y here. 1084 1085config UP_LATE_INIT 1086 def_bool y 1087 depends on !SMP && X86_LOCAL_APIC 1088 1089config X86_UP_APIC 1090 bool "Local APIC support on uniprocessors" if !PCI_MSI 1091 default PCI_MSI 1092 depends on X86_32 && !SMP 1093 help 1094 A local APIC (Advanced Programmable Interrupt Controller) is an 1095 integrated interrupt controller in the CPU. If you have a single-CPU 1096 system which has a processor with a local APIC, you can say Y here to 1097 enable and use it. If you say Y here even though your machine doesn't 1098 have a local APIC, then the kernel will still run with no slowdown at 1099 all. The local APIC supports CPU-generated self-interrupts (timer, 1100 performance counters), and the NMI watchdog which detects hard 1101 lockups. 1102 1103config X86_UP_IOAPIC 1104 bool "IO-APIC support on uniprocessors" 1105 depends on X86_UP_APIC 1106 help 1107 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1108 SMP-capable replacement for PC-style interrupt controllers. Most 1109 SMP systems and many recent uniprocessor systems have one. 1110 1111 If you have a single-CPU system with an IO-APIC, you can say Y here 1112 to use it. If you say Y here even though your machine doesn't have 1113 an IO-APIC, then the kernel will still run with no slowdown at all. 1114 1115config X86_LOCAL_APIC 1116 def_bool y 1117 depends on X86_64 || SMP || X86_UP_APIC || PCI_MSI 1118 select IRQ_DOMAIN_HIERARCHY 1119 1120config ACPI_MADT_WAKEUP 1121 def_bool y 1122 depends on X86_64 1123 depends on ACPI 1124 depends on SMP 1125 depends on X86_LOCAL_APIC 1126 1127config X86_IO_APIC 1128 def_bool y 1129 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1130 1131config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1132 bool "Reroute for broken boot IRQs" 1133 depends on X86_IO_APIC 1134 help 1135 This option enables a workaround that fixes a source of 1136 spurious interrupts. This is recommended when threaded 1137 interrupt handling is used on systems where the generation of 1138 superfluous "boot interrupts" cannot be disabled. 1139 1140 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1141 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1142 kernel does during interrupt handling). On chipsets where this 1143 boot IRQ generation cannot be disabled, this workaround keeps 1144 the original IRQ line masked so that only the equivalent "boot 1145 IRQ" is delivered to the CPUs. The workaround also tells the 1146 kernel to set up the IRQ handler on the boot IRQ line. In this 1147 way only one interrupt is delivered to the kernel. Otherwise 1148 the spurious second interrupt may cause the kernel to bring 1149 down (vital) interrupt lines. 1150 1151 Only affects "broken" chipsets. Interrupt sharing may be 1152 increased on these systems. 1153 1154config X86_MCE 1155 bool "Machine Check / overheating reporting" 1156 select GENERIC_ALLOCATOR 1157 default y 1158 help 1159 Machine Check support allows the processor to notify the 1160 kernel if it detects a problem (e.g. overheating, data corruption). 1161 The action the kernel takes depends on the severity of the problem, 1162 ranging from warning messages to halting the machine. 1163 1164config X86_MCELOG_LEGACY 1165 bool "Support for deprecated /dev/mcelog character device" 1166 depends on X86_MCE 1167 help 1168 Enable support for /dev/mcelog which is needed by the old mcelog 1169 userspace logging daemon. Consider switching to the new generation 1170 rasdaemon solution. 1171 1172config X86_MCE_INTEL 1173 def_bool y 1174 prompt "Intel MCE features" 1175 depends on X86_MCE && X86_LOCAL_APIC 1176 help 1177 Additional support for intel specific MCE features such as 1178 the thermal monitor. 1179 1180config X86_MCE_AMD 1181 def_bool y 1182 prompt "AMD MCE features" 1183 depends on X86_MCE && X86_LOCAL_APIC 1184 help 1185 Additional support for AMD specific MCE features such as 1186 the DRAM Error Threshold. 1187 1188config X86_ANCIENT_MCE 1189 bool "Support for old Pentium 5 / WinChip machine checks" 1190 depends on X86_32 && X86_MCE 1191 help 1192 Include support for machine check handling on old Pentium 5 or WinChip 1193 systems. These typically need to be enabled explicitly on the command 1194 line. 1195 1196config X86_MCE_THRESHOLD 1197 depends on X86_MCE_AMD || X86_MCE_INTEL 1198 def_bool y 1199 1200config X86_MCE_INJECT 1201 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1202 tristate "Machine check injector support" 1203 help 1204 Provide support for injecting machine checks for testing purposes. 1205 If you don't know what a machine check is and you don't do kernel 1206 QA it is safe to say n. 1207 1208source "arch/x86/events/Kconfig" 1209 1210config X86_LEGACY_VM86 1211 bool "Legacy VM86 support" 1212 depends on X86_32 1213 help 1214 This option allows user programs to put the CPU into V8086 1215 mode, which is an 80286-era approximation of 16-bit real mode. 1216 1217 Some very old versions of X and/or vbetool require this option 1218 for user mode setting. Similarly, DOSEMU will use it if 1219 available to accelerate real mode DOS programs. However, any 1220 recent version of DOSEMU, X, or vbetool should be fully 1221 functional even without kernel VM86 support, as they will all 1222 fall back to software emulation. Nevertheless, if you are using 1223 a 16-bit DOS program where 16-bit performance matters, vm86 1224 mode might be faster than emulation and you might want to 1225 enable this option. 1226 1227 Note that any app that works on a 64-bit kernel is unlikely to 1228 need this option, as 64-bit kernels don't, and can't, support 1229 V8086 mode. This option is also unrelated to 16-bit protected 1230 mode and is not needed to run most 16-bit programs under Wine. 1231 1232 Enabling this option increases the complexity of the kernel 1233 and slows down exception handling a tiny bit. 1234 1235 If unsure, say N here. 1236 1237config VM86 1238 bool 1239 default X86_LEGACY_VM86 1240 1241config X86_16BIT 1242 bool "Enable support for 16-bit segments" if EXPERT 1243 default y 1244 depends on MODIFY_LDT_SYSCALL 1245 help 1246 This option is required by programs like Wine to run 16-bit 1247 protected mode legacy code on x86 processors. Disabling 1248 this option saves about 300 bytes on i386, or around 6K text 1249 plus 16K runtime memory on x86-64, 1250 1251config X86_ESPFIX32 1252 def_bool y 1253 depends on X86_16BIT && X86_32 1254 1255config X86_ESPFIX64 1256 def_bool y 1257 depends on X86_16BIT && X86_64 1258 1259config X86_VSYSCALL_EMULATION 1260 bool "Enable vsyscall emulation" if EXPERT 1261 default y 1262 depends on X86_64 1263 help 1264 This enables emulation of the legacy vsyscall page. Disabling 1265 it is roughly equivalent to booting with vsyscall=none, except 1266 that it will also disable the helpful warning if a program 1267 tries to use a vsyscall. With this option set to N, offending 1268 programs will just segfault, citing addresses of the form 1269 0xffffffffff600?00. 1270 1271 This option is required by many programs built before 2013, and 1272 care should be used even with newer programs if set to N. 1273 1274 Disabling this option saves about 7K of kernel size and 1275 possibly 4K of additional runtime pagetable memory. 1276 1277config X86_IOPL_IOPERM 1278 bool "IOPERM and IOPL Emulation" 1279 default y 1280 help 1281 This enables the ioperm() and iopl() syscalls which are necessary 1282 for legacy applications. 1283 1284 Legacy IOPL support is an overbroad mechanism which allows user 1285 space aside of accessing all 65536 I/O ports also to disable 1286 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1287 capabilities and permission from potentially active security 1288 modules. 1289 1290 The emulation restricts the functionality of the syscall to 1291 only allowing the full range I/O port access, but prevents the 1292 ability to disable interrupts from user space which would be 1293 granted if the hardware IOPL mechanism would be used. 1294 1295config TOSHIBA 1296 tristate "Toshiba Laptop support" 1297 depends on X86_32 1298 help 1299 This adds a driver to safely access the System Management Mode of 1300 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1301 not work on models with a Phoenix BIOS. The System Management Mode 1302 is used to set the BIOS and power saving options on Toshiba portables. 1303 1304 For information on utilities to make use of this driver see the 1305 Toshiba Linux utilities web site at: 1306 <http://www.buzzard.org.uk/toshiba/>. 1307 1308 Say Y if you intend to run this kernel on a Toshiba portable. 1309 Say N otherwise. 1310 1311config X86_REBOOTFIXUPS 1312 bool "Enable X86 board specific fixups for reboot" 1313 depends on X86_32 1314 help 1315 This enables chipset and/or board specific fixups to be done 1316 in order to get reboot to work correctly. This is only needed on 1317 some combinations of hardware and BIOS. The symptom, for which 1318 this config is intended, is when reboot ends with a stalled/hung 1319 system. 1320 1321 Currently, the only fixup is for the Geode machines using 1322 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1323 1324 Say Y if you want to enable the fixup. Currently, it's safe to 1325 enable this option even if you don't need it. 1326 Say N otherwise. 1327 1328config MICROCODE 1329 def_bool y 1330 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1331 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD 1332 1333config MICROCODE_INITRD32 1334 def_bool y 1335 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1336 1337config MICROCODE_LATE_LOADING 1338 bool "Late microcode loading (DANGEROUS)" 1339 default n 1340 depends on MICROCODE && SMP 1341 help 1342 Loading microcode late, when the system is up and executing instructions 1343 is a tricky business and should be avoided if possible. Just the sequence 1344 of synchronizing all cores and SMT threads is one fragile dance which does 1345 not guarantee that cores might not softlock after the loading. Therefore, 1346 use this at your own risk. Late loading taints the kernel unless the 1347 microcode header indicates that it is safe for late loading via the 1348 minimal revision check. This minimal revision check can be enforced on 1349 the kernel command line with "microcode=force_minrev". 1350 1351config MICROCODE_LATE_FORCE_MINREV 1352 bool "Enforce late microcode loading minimal revision check" 1353 default n 1354 depends on MICROCODE_LATE_LOADING 1355 help 1356 To prevent that users load microcode late which modifies already 1357 in use features, newer microcode patches have a minimum revision field 1358 in the microcode header, which tells the kernel which minimum 1359 revision must be active in the CPU to safely load that new microcode 1360 late into the running system. If disabled the check will not 1361 be enforced but the kernel will be tainted when the minimal 1362 revision check fails. 1363 1364 This minimal revision check can also be controlled via the 1365 "microcode=force_minrev" parameter on the kernel command line. 1366 1367 If unsure say Y. 1368 1369config MICROCODE_DBG 1370 bool "Enable microcode loader debugging" 1371 default n 1372 depends on MICROCODE 1373 help 1374 Enable code which allows to debug the microcode loader. When running 1375 in a guest the patch loading is simulated but everything else 1376 related to patch parsing and handling is done as on baremetal with 1377 the purpose of debugging solely the software side of things. On 1378 baremetal, it simply dumps additional debugging information during 1379 normal operation. 1380 1381 You almost certainly want to say n here. 1382 1383config X86_MSR 1384 tristate "/dev/cpu/*/msr - Model-specific register support" 1385 help 1386 This device gives privileged processes access to the x86 1387 Model-Specific Registers (MSRs). It is a character device with 1388 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1389 MSR accesses are directed to a specific CPU on multi-processor 1390 systems. 1391 1392config X86_CPUID 1393 tristate "/dev/cpu/*/cpuid - CPU information support" 1394 help 1395 This device gives processes access to the x86 CPUID instruction to 1396 be executed on a specific processor. It is a character device 1397 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1398 /dev/cpu/31/cpuid. 1399 1400config HIGHMEM4G 1401 bool "High Memory Support" 1402 depends on X86_32 1403 help 1404 Linux can use up to 4 Gigabytes of physical memory on x86 systems. 1405 However, the address space of 32-bit x86 processors is only 4 1406 Gigabytes large. That means that, if you have a large amount of 1407 physical memory, not all of it can be "permanently mapped" by the 1408 kernel. The physical memory that's not permanently mapped is called 1409 "high memory". 1410 1411 If you are compiling a kernel which will never run on a machine with 1412 more than 1 Gigabyte total physical RAM, answer "off" here (default 1413 choice and suitable for most users). This will result in a "3GB/1GB" 1414 split: 3GB are mapped so that each process sees a 3GB virtual memory 1415 space and the remaining part of the 4GB virtual memory space is used 1416 by the kernel to permanently map as much physical memory as 1417 possible. 1418 1419 If the machine has between 1 and 4 Gigabytes physical RAM, then 1420 answer "Y" here. 1421 1422 If unsure, say N. 1423 1424choice 1425 prompt "Memory split" if EXPERT 1426 default VMSPLIT_3G 1427 depends on X86_32 1428 help 1429 Select the desired split between kernel and user memory. 1430 1431 If the address range available to the kernel is less than the 1432 physical memory installed, the remaining memory will be available 1433 as "high memory". Accessing high memory is a little more costly 1434 than low memory, as it needs to be mapped into the kernel first. 1435 Note that increasing the kernel address space limits the range 1436 available to user programs, making the address space there 1437 tighter. Selecting anything other than the default 3G/1G split 1438 will also likely make your kernel incompatible with binary-only 1439 kernel modules. 1440 1441 If you are not absolutely sure what you are doing, leave this 1442 option alone! 1443 1444 config VMSPLIT_3G 1445 bool "3G/1G user/kernel split" 1446 config VMSPLIT_3G_OPT 1447 depends on !X86_PAE 1448 bool "3G/1G user/kernel split (for full 1G low memory)" 1449 config VMSPLIT_2G 1450 bool "2G/2G user/kernel split" 1451 config VMSPLIT_2G_OPT 1452 depends on !X86_PAE 1453 bool "2G/2G user/kernel split (for full 2G low memory)" 1454 config VMSPLIT_1G 1455 bool "1G/3G user/kernel split" 1456endchoice 1457 1458config PAGE_OFFSET 1459 hex 1460 default 0xB0000000 if VMSPLIT_3G_OPT 1461 default 0x80000000 if VMSPLIT_2G 1462 default 0x78000000 if VMSPLIT_2G_OPT 1463 default 0x40000000 if VMSPLIT_1G 1464 default 0xC0000000 1465 depends on X86_32 1466 1467config HIGHMEM 1468 def_bool HIGHMEM4G 1469 1470config X86_PAE 1471 bool "PAE (Physical Address Extension) Support" 1472 depends on X86_32 && X86_HAVE_PAE 1473 select PHYS_ADDR_T_64BIT 1474 help 1475 PAE is required for NX support, and furthermore enables 1476 larger swapspace support for non-overcommit purposes. It 1477 has the cost of more pagetable lookup overhead, and also 1478 consumes more pagetable space per process. 1479 1480config X86_DIRECT_GBPAGES 1481 def_bool y 1482 depends on X86_64 1483 help 1484 Certain kernel features effectively disable kernel 1485 linear 1 GB mappings (even if the CPU otherwise 1486 supports them), so don't confuse the user by printing 1487 that we have them enabled. 1488 1489config X86_CPA_STATISTICS 1490 bool "Enable statistic for Change Page Attribute" 1491 depends on DEBUG_FS 1492 help 1493 Expose statistics about the Change Page Attribute mechanism, which 1494 helps to determine the effectiveness of preserving large and huge 1495 page mappings when mapping protections are changed. 1496 1497config X86_MEM_ENCRYPT 1498 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1499 select DYNAMIC_PHYSICAL_MASK 1500 def_bool n 1501 1502config AMD_MEM_ENCRYPT 1503 bool "AMD Secure Memory Encryption (SME) support" 1504 depends on X86_64 && CPU_SUP_AMD 1505 depends on EFI_STUB 1506 select DMA_COHERENT_POOL 1507 select ARCH_USE_MEMREMAP_PROT 1508 select INSTRUCTION_DECODER 1509 select ARCH_HAS_CC_PLATFORM 1510 select X86_MEM_ENCRYPT 1511 select UNACCEPTED_MEMORY 1512 select CRYPTO_LIB_AESGCM 1513 help 1514 Say yes to enable support for the encryption of system memory. 1515 This requires an AMD processor that supports Secure Memory 1516 Encryption (SME). 1517 1518# Common NUMA Features 1519config NUMA 1520 bool "NUMA Memory Allocation and Scheduler Support" 1521 depends on SMP 1522 depends on X86_64 1523 select USE_PERCPU_NUMA_NODE_ID 1524 select OF_NUMA if OF 1525 help 1526 Enable NUMA (Non-Uniform Memory Access) support. 1527 1528 The kernel will try to allocate memory used by a CPU on the 1529 local memory controller of the CPU and add some more 1530 NUMA awareness to the kernel. 1531 1532 For 64-bit this is recommended if the system is Intel Core i7 1533 (or later), AMD Opteron, or EM64T NUMA. 1534 1535 Otherwise, you should say N. 1536 1537config AMD_NUMA 1538 def_bool y 1539 prompt "Old style AMD Opteron NUMA detection" 1540 depends on X86_64 && NUMA && PCI 1541 help 1542 Enable AMD NUMA node topology detection. You should say Y here if 1543 you have a multi processor AMD system. This uses an old method to 1544 read the NUMA configuration directly from the builtin Northbridge 1545 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1546 which also takes priority if both are compiled in. 1547 1548config X86_64_ACPI_NUMA 1549 def_bool y 1550 prompt "ACPI NUMA detection" 1551 depends on X86_64 && NUMA && ACPI && PCI 1552 select ACPI_NUMA 1553 help 1554 Enable ACPI SRAT based node topology detection. 1555 1556config NODES_SHIFT 1557 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1558 range 1 10 1559 default "10" if MAXSMP 1560 default "6" if X86_64 1561 default "3" 1562 depends on NUMA 1563 help 1564 Specify the maximum number of NUMA Nodes available on the target 1565 system. Increases memory reserved to accommodate various tables. 1566 1567config ARCH_FLATMEM_ENABLE 1568 def_bool y 1569 depends on X86_32 && !NUMA 1570 1571config ARCH_SPARSEMEM_ENABLE 1572 def_bool y 1573 select SPARSEMEM_STATIC if X86_32 1574 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1575 1576config ARCH_SPARSEMEM_DEFAULT 1577 def_bool X86_64 || (NUMA && X86_32) 1578 1579config ARCH_SELECT_MEMORY_MODEL 1580 def_bool y 1581 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1582 1583config ARCH_MEMORY_PROBE 1584 bool "Enable sysfs memory/probe interface" 1585 depends on MEMORY_HOTPLUG 1586 help 1587 This option enables a sysfs memory/probe interface for testing. 1588 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1589 If you are unsure how to answer this question, answer N. 1590 1591config ARCH_PROC_KCORE_TEXT 1592 def_bool y 1593 depends on X86_64 && PROC_KCORE 1594 1595config ILLEGAL_POINTER_VALUE 1596 hex 1597 default 0 if X86_32 1598 default 0xdead000000000000 if X86_64 1599 1600config X86_PMEM_LEGACY_DEVICE 1601 bool 1602 1603config X86_PMEM_LEGACY 1604 tristate "Support non-standard NVDIMMs and ADR protected memory" 1605 depends on PHYS_ADDR_T_64BIT 1606 depends on BLK_DEV 1607 select X86_PMEM_LEGACY_DEVICE 1608 select NUMA_KEEP_MEMINFO if NUMA 1609 select LIBNVDIMM 1610 help 1611 Treat memory marked using the non-standard e820 type of 12 as used 1612 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1613 The kernel will offer these regions to the 'pmem' driver so 1614 they can be used for persistent storage. 1615 1616 Say Y if unsure. 1617 1618config X86_CHECK_BIOS_CORRUPTION 1619 bool "Check for low memory corruption" 1620 help 1621 Periodically check for memory corruption in low memory, which 1622 is suspected to be caused by BIOS. Even when enabled in the 1623 configuration, it is disabled at runtime. Enable it by 1624 setting "memory_corruption_check=1" on the kernel command 1625 line. By default it scans the low 64k of memory every 60 1626 seconds; see the memory_corruption_check_size and 1627 memory_corruption_check_period parameters in 1628 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1629 1630 When enabled with the default parameters, this option has 1631 almost no overhead, as it reserves a relatively small amount 1632 of memory and scans it infrequently. It both detects corruption 1633 and prevents it from affecting the running system. 1634 1635 It is, however, intended as a diagnostic tool; if repeatable 1636 BIOS-originated corruption always affects the same memory, 1637 you can use memmap= to prevent the kernel from using that 1638 memory. 1639 1640config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1641 bool "Set the default setting of memory_corruption_check" 1642 depends on X86_CHECK_BIOS_CORRUPTION 1643 default y 1644 help 1645 Set whether the default state of memory_corruption_check is 1646 on or off. 1647 1648config MATH_EMULATION 1649 bool 1650 depends on MODIFY_LDT_SYSCALL 1651 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1652 help 1653 Linux can emulate a math coprocessor (used for floating point 1654 operations) if you don't have one. 486DX and Pentium processors have 1655 a math coprocessor built in, 486SX and 386 do not, unless you added 1656 a 487DX or 387, respectively. (The messages during boot time can 1657 give you some hints here ["man dmesg"].) Everyone needs either a 1658 coprocessor or this emulation. 1659 1660 If you don't have a math coprocessor, you need to say Y here; if you 1661 say Y here even though you have a coprocessor, the coprocessor will 1662 be used nevertheless. (This behavior can be changed with the kernel 1663 command line option "no387", which comes handy if your coprocessor 1664 is broken. Try "man bootparam" or see the documentation of your boot 1665 loader (lilo or loadlin) about how to pass options to the kernel at 1666 boot time.) This means that it is a good idea to say Y here if you 1667 intend to use this kernel on different machines. 1668 1669 More information about the internals of the Linux math coprocessor 1670 emulation can be found in <file:arch/x86/math-emu/README>. 1671 1672 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1673 kernel, it won't hurt. 1674 1675config MTRR 1676 def_bool y 1677 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1678 help 1679 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1680 the Memory Type Range Registers (MTRRs) may be used to control 1681 processor access to memory ranges. This is most useful if you have 1682 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1683 allows bus write transfers to be combined into a larger transfer 1684 before bursting over the PCI/AGP bus. This can increase performance 1685 of image write operations 2.5 times or more. Saying Y here creates a 1686 /proc/mtrr file which may be used to manipulate your processor's 1687 MTRRs. Typically the X server should use this. 1688 1689 This code has a reasonably generic interface so that similar 1690 control registers on other processors can be easily supported 1691 as well: 1692 1693 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1694 Registers (ARRs) which provide a similar functionality to MTRRs. For 1695 these, the ARRs are used to emulate the MTRRs. 1696 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1697 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1698 write-combining. All of these processors are supported by this code 1699 and it makes sense to say Y here if you have one of them. 1700 1701 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1702 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1703 can lead to all sorts of problems, so it's good to say Y here. 1704 1705 You can safely say Y even if your machine doesn't have MTRRs, you'll 1706 just add about 9 KB to your kernel. 1707 1708 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1709 1710config MTRR_SANITIZER 1711 def_bool y 1712 prompt "MTRR cleanup support" 1713 depends on MTRR 1714 help 1715 Convert MTRR layout from continuous to discrete, so X drivers can 1716 add writeback entries. 1717 1718 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1719 The largest mtrr entry size for a continuous block can be set with 1720 mtrr_chunk_size. 1721 1722 If unsure, say Y. 1723 1724config MTRR_SANITIZER_ENABLE_DEFAULT 1725 int "MTRR cleanup enable value (0-1)" 1726 range 0 1 1727 default "0" 1728 depends on MTRR_SANITIZER 1729 help 1730 Enable mtrr cleanup default value 1731 1732config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1733 int "MTRR cleanup spare reg num (0-7)" 1734 range 0 7 1735 default "1" 1736 depends on MTRR_SANITIZER 1737 help 1738 mtrr cleanup spare entries default, it can be changed via 1739 mtrr_spare_reg_nr=N on the kernel command line. 1740 1741config X86_PAT 1742 def_bool y 1743 prompt "x86 PAT support" if EXPERT 1744 depends on MTRR 1745 select ARCH_USES_PG_ARCH_2 1746 help 1747 Use PAT attributes to setup page level cache control. 1748 1749 PATs are the modern equivalents of MTRRs and are much more 1750 flexible than MTRRs. 1751 1752 Say N here if you see bootup problems (boot crash, boot hang, 1753 spontaneous reboots) or a non-working video driver. 1754 1755 If unsure, say Y. 1756 1757config X86_UMIP 1758 def_bool y 1759 prompt "User Mode Instruction Prevention" if EXPERT 1760 help 1761 User Mode Instruction Prevention (UMIP) is a security feature in 1762 some x86 processors. If enabled, a general protection fault is 1763 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1764 executed in user mode. These instructions unnecessarily expose 1765 information about the hardware state. 1766 1767 The vast majority of applications do not use these instructions. 1768 For the very few that do, software emulation is provided in 1769 specific cases in protected and virtual-8086 modes. Emulated 1770 results are dummy. 1771 1772config CC_HAS_IBT 1773 # GCC >= 9 and binutils >= 2.29 1774 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1775 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || CC_IS_CLANG) && \ 1776 $(as-instr,endbr64) 1777 1778config X86_CET 1779 def_bool n 1780 help 1781 CET features configured (Shadow stack or IBT) 1782 1783config X86_KERNEL_IBT 1784 prompt "Indirect Branch Tracking" 1785 def_bool y 1786 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1787 select OBJTOOL 1788 select X86_CET 1789 help 1790 Build the kernel with support for Indirect Branch Tracking, a 1791 hardware support course-grain forward-edge Control Flow Integrity 1792 protection. It enforces that all indirect calls must land on 1793 an ENDBR instruction, as such, the compiler will instrument the 1794 code with them to make this happen. 1795 1796 In addition to building the kernel with IBT, seal all functions that 1797 are not indirect call targets, avoiding them ever becoming one. 1798 1799 This requires LTO like objtool runs and will slow down the build. It 1800 does significantly reduce the number of ENDBR instructions in the 1801 kernel image. 1802 1803config X86_INTEL_MEMORY_PROTECTION_KEYS 1804 prompt "Memory Protection Keys" 1805 def_bool y 1806 # Note: only available in 64-bit mode 1807 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1808 select ARCH_USES_HIGH_VMA_FLAGS 1809 select ARCH_HAS_PKEYS 1810 help 1811 Memory Protection Keys provides a mechanism for enforcing 1812 page-based protections, but without requiring modification of the 1813 page tables when an application changes protection domains. 1814 1815 For details, see Documentation/core-api/protection-keys.rst 1816 1817 If unsure, say y. 1818 1819config ARCH_PKEY_BITS 1820 int 1821 default 4 1822 1823choice 1824 prompt "TSX enable mode" 1825 depends on CPU_SUP_INTEL 1826 default X86_INTEL_TSX_MODE_AUTO 1827 help 1828 Intel's TSX (Transactional Synchronization Extensions) feature 1829 allows to optimize locking protocols through lock elision which 1830 can lead to a noticeable performance boost. 1831 1832 On the other hand it has been shown that TSX can be exploited 1833 to form side channel attacks (e.g. TAA) and chances are there 1834 will be more of those attacks discovered in the future. 1835 1836 Therefore TSX is not enabled by default (aka tsx=off). An admin 1837 might override this decision by tsx=on the command line parameter. 1838 Even with TSX enabled, the kernel will attempt to enable the best 1839 possible TAA mitigation setting depending on the microcode available 1840 for the particular machine. 1841 1842 This option allows to set the default tsx mode between tsx=on, =off 1843 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1844 details. 1845 1846 Say off if not sure, auto if TSX is in use but it should be used on safe 1847 platforms or on if TSX is in use and the security aspect of tsx is not 1848 relevant. 1849 1850config X86_INTEL_TSX_MODE_OFF 1851 bool "off" 1852 help 1853 TSX is disabled if possible - equals to tsx=off command line parameter. 1854 1855config X86_INTEL_TSX_MODE_ON 1856 bool "on" 1857 help 1858 TSX is always enabled on TSX capable HW - equals the tsx=on command 1859 line parameter. 1860 1861config X86_INTEL_TSX_MODE_AUTO 1862 bool "auto" 1863 help 1864 TSX is enabled on TSX capable HW that is believed to be safe against 1865 side channel attacks- equals the tsx=auto command line parameter. 1866endchoice 1867 1868config X86_SGX 1869 bool "Software Guard eXtensions (SGX)" 1870 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1871 select CRYPTO_LIB_SHA256 1872 select MMU_NOTIFIER 1873 select NUMA_KEEP_MEMINFO if NUMA 1874 select XARRAY_MULTI 1875 help 1876 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1877 that can be used by applications to set aside private regions of code 1878 and data, referred to as enclaves. An enclave's private memory can 1879 only be accessed by code running within the enclave. Accesses from 1880 outside the enclave, including other enclaves, are disallowed by 1881 hardware. 1882 1883 If unsure, say N. 1884 1885config X86_USER_SHADOW_STACK 1886 bool "X86 userspace shadow stack" 1887 depends on AS_WRUSS 1888 depends on X86_64 1889 select ARCH_USES_HIGH_VMA_FLAGS 1890 select ARCH_HAS_USER_SHADOW_STACK 1891 select X86_CET 1892 help 1893 Shadow stack protection is a hardware feature that detects function 1894 return address corruption. This helps mitigate ROP attacks. 1895 Applications must be enabled to use it, and old userspace does not 1896 get protection "for free". 1897 1898 CPUs supporting shadow stacks were first released in 2020. 1899 1900 See Documentation/arch/x86/shstk.rst for more information. 1901 1902 If unsure, say N. 1903 1904config INTEL_TDX_HOST 1905 bool "Intel Trust Domain Extensions (TDX) host support" 1906 depends on CPU_SUP_INTEL 1907 depends on X86_64 1908 depends on KVM_INTEL 1909 depends on X86_X2APIC 1910 select ARCH_KEEP_MEMBLOCK 1911 depends on CONTIG_ALLOC 1912 depends on X86_MCE 1913 help 1914 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1915 host and certain physical attacks. This option enables necessary TDX 1916 support in the host kernel to run confidential VMs. 1917 1918 If unsure, say N. 1919 1920config EFI 1921 bool "EFI runtime service support" 1922 depends on ACPI 1923 select UCS2_STRING 1924 select EFI_RUNTIME_WRAPPERS 1925 select ARCH_USE_MEMREMAP_PROT 1926 select EFI_RUNTIME_MAP if KEXEC_CORE 1927 help 1928 This enables the kernel to use EFI runtime services that are 1929 available (such as the EFI variable services). 1930 1931 This option is only useful on systems that have EFI firmware. 1932 In addition, you should use the latest ELILO loader available 1933 at <http://elilo.sourceforge.net> in order to take advantage 1934 of EFI runtime services. However, even with this option, the 1935 resultant kernel should continue to boot on existing non-EFI 1936 platforms. 1937 1938config EFI_STUB 1939 bool "EFI stub support" 1940 depends on EFI 1941 select RELOCATABLE 1942 help 1943 This kernel feature allows a bzImage to be loaded directly 1944 by EFI firmware without the use of a bootloader. 1945 1946 See Documentation/admin-guide/efi-stub.rst for more information. 1947 1948config EFI_HANDOVER_PROTOCOL 1949 bool "EFI handover protocol (DEPRECATED)" 1950 depends on EFI_STUB 1951 default y 1952 help 1953 Select this in order to include support for the deprecated EFI 1954 handover protocol, which defines alternative entry points into the 1955 EFI stub. This is a practice that has no basis in the UEFI 1956 specification, and requires a priori knowledge on the part of the 1957 bootloader about Linux/x86 specific ways of passing the command line 1958 and initrd, and where in memory those assets may be loaded. 1959 1960 If in doubt, say Y. Even though the corresponding support is not 1961 present in upstream GRUB or other bootloaders, most distros build 1962 GRUB with numerous downstream patches applied, and may rely on the 1963 handover protocol as as result. 1964 1965config EFI_MIXED 1966 bool "EFI mixed-mode support" 1967 depends on EFI_STUB && X86_64 1968 help 1969 Enabling this feature allows a 64-bit kernel to be booted 1970 on a 32-bit firmware, provided that your CPU supports 64-bit 1971 mode. 1972 1973 Note that it is not possible to boot a mixed-mode enabled 1974 kernel via the EFI boot stub - a bootloader that supports 1975 the EFI handover protocol must be used. 1976 1977 If unsure, say N. 1978 1979config EFI_RUNTIME_MAP 1980 bool "Export EFI runtime maps to sysfs" if EXPERT 1981 depends on EFI 1982 help 1983 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 1984 That memory map is required by the 2nd kernel to set up EFI virtual 1985 mappings after kexec, but can also be used for debugging purposes. 1986 1987 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 1988 1989source "kernel/Kconfig.hz" 1990 1991config ARCH_SUPPORTS_KEXEC 1992 def_bool y 1993 1994config ARCH_SUPPORTS_KEXEC_FILE 1995 def_bool X86_64 1996 1997config ARCH_SELECTS_KEXEC_FILE 1998 def_bool y 1999 depends on KEXEC_FILE 2000 select HAVE_IMA_KEXEC if IMA 2001 2002config ARCH_SUPPORTS_KEXEC_PURGATORY 2003 def_bool y 2004 2005config ARCH_SUPPORTS_KEXEC_SIG 2006 def_bool y 2007 2008config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2009 def_bool y 2010 2011config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2012 def_bool y 2013 2014config ARCH_SUPPORTS_KEXEC_JUMP 2015 def_bool y 2016 2017config ARCH_SUPPORTS_KEXEC_HANDOVER 2018 def_bool X86_64 2019 2020config ARCH_SUPPORTS_CRASH_DUMP 2021 def_bool X86_64 || (X86_32 && HIGHMEM) 2022 2023config ARCH_DEFAULT_CRASH_DUMP 2024 def_bool y 2025 2026config ARCH_SUPPORTS_CRASH_HOTPLUG 2027 def_bool y 2028 2029config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2030 def_bool CRASH_RESERVE 2031 2032config PHYSICAL_START 2033 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2034 default "0x1000000" 2035 help 2036 This gives the physical address where the kernel is loaded. 2037 2038 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2039 will decompress itself to above physical address and run from there. 2040 Otherwise, bzImage will run from the address where it has been loaded 2041 by the boot loader. The only exception is if it is loaded below the 2042 above physical address, in which case it will relocate itself there. 2043 2044 In normal kdump cases one does not have to set/change this option 2045 as now bzImage can be compiled as a completely relocatable image 2046 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2047 address. This option is mainly useful for the folks who don't want 2048 to use a bzImage for capturing the crash dump and want to use a 2049 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2050 to be specifically compiled to run from a specific memory area 2051 (normally a reserved region) and this option comes handy. 2052 2053 So if you are using bzImage for capturing the crash dump, 2054 leave the value here unchanged to 0x1000000 and set 2055 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2056 for capturing the crash dump change this value to start of 2057 the reserved region. In other words, it can be set based on 2058 the "X" value as specified in the "crashkernel=YM@XM" 2059 command line boot parameter passed to the panic-ed 2060 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2061 for more details about crash dumps. 2062 2063 Usage of bzImage for capturing the crash dump is recommended as 2064 one does not have to build two kernels. Same kernel can be used 2065 as production kernel and capture kernel. Above option should have 2066 gone away after relocatable bzImage support is introduced. But it 2067 is present because there are users out there who continue to use 2068 vmlinux for dump capture. This option should go away down the 2069 line. 2070 2071 Don't change this unless you know what you are doing. 2072 2073config RELOCATABLE 2074 bool "Build a relocatable kernel" 2075 default y 2076 help 2077 This builds a kernel image that retains relocation information 2078 so it can be loaded someplace besides the default 1MB. 2079 The relocations tend to make the kernel binary about 10% larger, 2080 but are discarded at runtime. 2081 2082 One use is for the kexec on panic case where the recovery kernel 2083 must live at a different physical address than the primary 2084 kernel. 2085 2086 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2087 it has been loaded at and the compile time physical address 2088 (CONFIG_PHYSICAL_START) is used as the minimum location. 2089 2090config RANDOMIZE_BASE 2091 bool "Randomize the address of the kernel image (KASLR)" 2092 depends on RELOCATABLE 2093 default y 2094 help 2095 In support of Kernel Address Space Layout Randomization (KASLR), 2096 this randomizes the physical address at which the kernel image 2097 is decompressed and the virtual address where the kernel 2098 image is mapped, as a security feature that deters exploit 2099 attempts relying on knowledge of the location of kernel 2100 code internals. 2101 2102 On 64-bit, the kernel physical and virtual addresses are 2103 randomized separately. The physical address will be anywhere 2104 between 16MB and the top of physical memory (up to 64TB). The 2105 virtual address will be randomized from 16MB up to 1GB (9 bits 2106 of entropy). Note that this also reduces the memory space 2107 available to kernel modules from 1.5GB to 1GB. 2108 2109 On 32-bit, the kernel physical and virtual addresses are 2110 randomized together. They will be randomized from 16MB up to 2111 512MB (8 bits of entropy). 2112 2113 Entropy is generated using the RDRAND instruction if it is 2114 supported. If RDTSC is supported, its value is mixed into 2115 the entropy pool as well. If neither RDRAND nor RDTSC are 2116 supported, then entropy is read from the i8254 timer. The 2117 usable entropy is limited by the kernel being built using 2118 2GB addressing, and that PHYSICAL_ALIGN must be at a 2119 minimum of 2MB. As a result, only 10 bits of entropy are 2120 theoretically possible, but the implementations are further 2121 limited due to memory layouts. 2122 2123 If unsure, say Y. 2124 2125# Relocation on x86 needs some additional build support 2126config X86_NEED_RELOCS 2127 def_bool y 2128 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2129 select ARCH_VMLINUX_NEEDS_RELOCS 2130 2131config PHYSICAL_ALIGN 2132 hex "Alignment value to which kernel should be aligned" 2133 default "0x200000" 2134 range 0x2000 0x1000000 if X86_32 2135 range 0x200000 0x1000000 if X86_64 2136 help 2137 This value puts the alignment restrictions on physical address 2138 where kernel is loaded and run from. Kernel is compiled for an 2139 address which meets above alignment restriction. 2140 2141 If bootloader loads the kernel at a non-aligned address and 2142 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2143 address aligned to above value and run from there. 2144 2145 If bootloader loads the kernel at a non-aligned address and 2146 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2147 load address and decompress itself to the address it has been 2148 compiled for and run from there. The address for which kernel is 2149 compiled already meets above alignment restrictions. Hence the 2150 end result is that kernel runs from a physical address meeting 2151 above alignment restrictions. 2152 2153 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2154 this value must be a multiple of 0x200000. 2155 2156 Don't change this unless you know what you are doing. 2157 2158config RANDOMIZE_MEMORY 2159 bool "Randomize the kernel memory sections" 2160 depends on X86_64 2161 depends on RANDOMIZE_BASE 2162 default RANDOMIZE_BASE 2163 help 2164 Randomizes the base virtual address of kernel memory sections 2165 (physical memory mapping, vmalloc & vmemmap). This security feature 2166 makes exploits relying on predictable memory locations less reliable. 2167 2168 The order of allocations remains unchanged. Entropy is generated in 2169 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2170 configuration have in average 30,000 different possible virtual 2171 addresses for each memory section. 2172 2173 If unsure, say Y. 2174 2175config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2176 hex "Physical memory mapping padding" if EXPERT 2177 depends on RANDOMIZE_MEMORY 2178 default "0xa" if MEMORY_HOTPLUG 2179 default "0x0" 2180 range 0x1 0x40 if MEMORY_HOTPLUG 2181 range 0x0 0x40 2182 help 2183 Define the padding in terabytes added to the existing physical 2184 memory size during kernel memory randomization. It is useful 2185 for memory hotplug support but reduces the entropy available for 2186 address randomization. 2187 2188 If unsure, leave at the default value. 2189 2190config ADDRESS_MASKING 2191 bool "Linear Address Masking support" 2192 depends on X86_64 2193 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2194 help 2195 Linear Address Masking (LAM) modifies the checking that is applied 2196 to 64-bit linear addresses, allowing software to use of the 2197 untranslated address bits for metadata. 2198 2199 The capability can be used for efficient address sanitizers (ASAN) 2200 implementation and for optimizations in JITs. 2201 2202config HOTPLUG_CPU 2203 def_bool y 2204 depends on SMP 2205 2206config COMPAT_VDSO 2207 def_bool n 2208 prompt "Workaround for glibc 2.3.2 / 2.3.3 (released in year 2003/2004)" 2209 depends on COMPAT_32 2210 help 2211 Certain buggy versions of glibc will crash if they are 2212 presented with a 32-bit vDSO that is not mapped at the address 2213 indicated in its segment table. 2214 2215 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2216 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2217 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2218 the only released version with the bug, but OpenSUSE 9 2219 contains a buggy "glibc 2.3.2". 2220 2221 The symptom of the bug is that everything crashes on startup, saying: 2222 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2223 2224 Saying Y here changes the default value of the vdso32 boot 2225 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2226 This works around the glibc bug but hurts performance. 2227 2228 If unsure, say N: if you are compiling your own kernel, you 2229 are unlikely to be using a buggy version of glibc. 2230 2231choice 2232 prompt "vsyscall table for legacy applications" 2233 depends on X86_64 2234 default LEGACY_VSYSCALL_XONLY 2235 help 2236 Legacy user code that does not know how to find the vDSO expects 2237 to be able to issue three syscalls by calling fixed addresses in 2238 kernel space. Since this location is not randomized with ASLR, 2239 it can be used to assist security vulnerability exploitation. 2240 2241 This setting can be changed at boot time via the kernel command 2242 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2243 is deprecated and can only be enabled using the kernel command 2244 line. 2245 2246 On a system with recent enough glibc (2.14 or newer) and no 2247 static binaries, you can say None without a performance penalty 2248 to improve security. 2249 2250 If unsure, select "Emulate execution only". 2251 2252 config LEGACY_VSYSCALL_XONLY 2253 bool "Emulate execution only" 2254 help 2255 The kernel traps and emulates calls into the fixed vsyscall 2256 address mapping and does not allow reads. This 2257 configuration is recommended when userspace might use the 2258 legacy vsyscall area but support for legacy binary 2259 instrumentation of legacy code is not needed. It mitigates 2260 certain uses of the vsyscall area as an ASLR-bypassing 2261 buffer. 2262 2263 config LEGACY_VSYSCALL_NONE 2264 bool "None" 2265 help 2266 There will be no vsyscall mapping at all. This will 2267 eliminate any risk of ASLR bypass due to the vsyscall 2268 fixed address mapping. Attempts to use the vsyscalls 2269 will be reported to dmesg, so that either old or 2270 malicious userspace programs can be identified. 2271 2272endchoice 2273 2274config CMDLINE_BOOL 2275 bool "Built-in kernel command line" 2276 help 2277 Allow for specifying boot arguments to the kernel at 2278 build time. On some systems (e.g. embedded ones), it is 2279 necessary or convenient to provide some or all of the 2280 kernel boot arguments with the kernel itself (that is, 2281 to not rely on the boot loader to provide them.) 2282 2283 To compile command line arguments into the kernel, 2284 set this option to 'Y', then fill in the 2285 boot arguments in CONFIG_CMDLINE. 2286 2287 Systems with fully functional boot loaders (i.e. non-embedded) 2288 should leave this option set to 'N'. 2289 2290config CMDLINE 2291 string "Built-in kernel command string" 2292 depends on CMDLINE_BOOL 2293 default "" 2294 help 2295 Enter arguments here that should be compiled into the kernel 2296 image and used at boot time. If the boot loader provides a 2297 command line at boot time, it is appended to this string to 2298 form the full kernel command line, when the system boots. 2299 2300 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2301 change this behavior. 2302 2303 In most cases, the command line (whether built-in or provided 2304 by the boot loader) should specify the device for the root 2305 file system. 2306 2307config CMDLINE_OVERRIDE 2308 bool "Built-in command line overrides boot loader arguments" 2309 depends on CMDLINE_BOOL && CMDLINE != "" 2310 help 2311 Set this option to 'Y' to have the kernel ignore the boot loader 2312 command line, and use ONLY the built-in command line. 2313 2314 This is used to work around broken boot loaders. This should 2315 be set to 'N' under normal conditions. 2316 2317config MODIFY_LDT_SYSCALL 2318 bool "Enable the LDT (local descriptor table)" if EXPERT 2319 default y 2320 help 2321 Linux can allow user programs to install a per-process x86 2322 Local Descriptor Table (LDT) using the modify_ldt(2) system 2323 call. This is required to run 16-bit or segmented code such as 2324 DOSEMU or some Wine programs. It is also used by some very old 2325 threading libraries. 2326 2327 Enabling this feature adds a small amount of overhead to 2328 context switches and increases the low-level kernel attack 2329 surface. Disabling it removes the modify_ldt(2) system call. 2330 2331 Saying 'N' here may make sense for embedded or server kernels. 2332 2333config STRICT_SIGALTSTACK_SIZE 2334 bool "Enforce strict size checking for sigaltstack" 2335 depends on DYNAMIC_SIGFRAME 2336 help 2337 For historical reasons MINSIGSTKSZ is a constant which became 2338 already too small with AVX512 support. Add a mechanism to 2339 enforce strict checking of the sigaltstack size against the 2340 real size of the FPU frame. This option enables the check 2341 by default. It can also be controlled via the kernel command 2342 line option 'strict_sas_size' independent of this config 2343 switch. Enabling it might break existing applications which 2344 allocate a too small sigaltstack but 'work' because they 2345 never get a signal delivered. 2346 2347 Say 'N' unless you want to really enforce this check. 2348 2349config CFI_AUTO_DEFAULT 2350 bool "Attempt to use FineIBT by default at boot time" 2351 depends on FINEIBT 2352 depends on !RUST || RUSTC_VERSION >= 108800 2353 default y 2354 help 2355 Attempt to use FineIBT by default at boot time. If enabled, 2356 this is the same as booting with "cfi=auto". If disabled, 2357 this is the same as booting with "cfi=kcfi". 2358 2359source "kernel/livepatch/Kconfig" 2360 2361config X86_BUS_LOCK_DETECT 2362 bool "Split Lock Detect and Bus Lock Detect support" 2363 depends on CPU_SUP_INTEL || CPU_SUP_AMD 2364 default y 2365 help 2366 Enable Split Lock Detect and Bus Lock Detect functionalities. 2367 See <file:Documentation/arch/x86/buslock.rst> for more information. 2368 2369endmenu 2370 2371config CC_HAS_NAMED_AS 2372 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null) 2373 depends on CC_IS_GCC 2374 2375# 2376# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN) 2377# are incompatible with named address spaces with GCC < 13.3 2378# (see GCC PR sanitizer/111736 and also PR sanitizer/115172). 2379# 2380 2381config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2382 def_bool y 2383 depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300 2384 depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200 2385 2386config USE_X86_SEG_SUPPORT 2387 def_bool CC_HAS_NAMED_AS 2388 depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS 2389 2390config CC_HAS_SLS 2391 def_bool $(cc-option,-mharden-sls=all) 2392 2393config CC_HAS_RETURN_THUNK 2394 def_bool $(cc-option,-mfunction-return=thunk-extern) 2395 2396config CC_HAS_ENTRY_PADDING 2397 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2398 2399config CC_HAS_KCFI_ARITY 2400 def_bool $(cc-option,-fsanitize=kcfi -fsanitize-kcfi-arity) 2401 depends on CC_IS_CLANG && !RUST 2402 2403config FUNCTION_PADDING_CFI 2404 int 2405 default 59 if FUNCTION_ALIGNMENT_64B 2406 default 27 if FUNCTION_ALIGNMENT_32B 2407 default 11 if FUNCTION_ALIGNMENT_16B 2408 default 3 if FUNCTION_ALIGNMENT_8B 2409 default 0 2410 2411# Basically: FUNCTION_ALIGNMENT - 5*CFI 2412# except Kconfig can't do arithmetic :/ 2413config FUNCTION_PADDING_BYTES 2414 int 2415 default FUNCTION_PADDING_CFI if CFI 2416 default FUNCTION_ALIGNMENT 2417 2418config CALL_PADDING 2419 def_bool n 2420 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2421 select FUNCTION_ALIGNMENT_16B 2422 2423config FINEIBT 2424 def_bool y 2425 depends on X86_KERNEL_IBT && CFI && MITIGATION_RETPOLINE 2426 select CALL_PADDING 2427 2428config FINEIBT_BHI 2429 def_bool y 2430 depends on FINEIBT && CC_HAS_KCFI_ARITY 2431 2432config HAVE_CALL_THUNKS 2433 def_bool y 2434 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2435 2436config CALL_THUNKS 2437 def_bool n 2438 select CALL_PADDING 2439 2440config PREFIX_SYMBOLS 2441 def_bool y 2442 depends on CALL_PADDING && !CFI 2443 2444menuconfig CPU_MITIGATIONS 2445 bool "Mitigations for CPU vulnerabilities" 2446 default y 2447 help 2448 Say Y here to enable options which enable mitigations for hardware 2449 vulnerabilities (usually related to speculative execution). 2450 Mitigations can be disabled or restricted to SMT systems at runtime 2451 via the "mitigations" kernel parameter. 2452 2453 If you say N, all mitigations will be disabled. This CANNOT be 2454 overridden at runtime. 2455 2456 Say 'Y', unless you really know what you are doing. 2457 2458if CPU_MITIGATIONS 2459 2460config MITIGATION_PAGE_TABLE_ISOLATION 2461 bool "Remove the kernel mapping in user mode" 2462 default y 2463 depends on (X86_64 || X86_PAE) 2464 help 2465 This feature reduces the number of hardware side channels by 2466 ensuring that the majority of kernel addresses are not mapped 2467 into userspace. 2468 2469 See Documentation/arch/x86/pti.rst for more details. 2470 2471config MITIGATION_RETPOLINE 2472 bool "Avoid speculative indirect branches in kernel" 2473 select OBJTOOL if HAVE_OBJTOOL 2474 default y 2475 help 2476 Compile kernel with the retpoline compiler options to guard against 2477 kernel-to-user data leaks by avoiding speculative indirect 2478 branches. Requires a compiler with -mindirect-branch=thunk-extern 2479 support for full protection. The kernel may run slower. 2480 2481config MITIGATION_RETHUNK 2482 bool "Enable return-thunks" 2483 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2484 select OBJTOOL if HAVE_OBJTOOL 2485 default y if X86_64 2486 help 2487 Compile the kernel with the return-thunks compiler option to guard 2488 against kernel-to-user data leaks by avoiding return speculation. 2489 Requires a compiler with -mfunction-return=thunk-extern 2490 support for full protection. The kernel may run slower. 2491 2492config MITIGATION_UNRET_ENTRY 2493 bool "Enable UNRET on kernel entry" 2494 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2495 default y 2496 help 2497 Compile the kernel with support for the retbleed=unret mitigation. 2498 2499config MITIGATION_CALL_DEPTH_TRACKING 2500 bool "Mitigate RSB underflow with call depth tracking" 2501 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2502 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2503 select CALL_THUNKS 2504 default y 2505 help 2506 Compile the kernel with call depth tracking to mitigate the Intel 2507 SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off 2508 by default and needs to be enabled on the kernel command line via the 2509 retbleed=stuff option. For non-affected systems the overhead of this 2510 option is marginal as the call depth tracking is using run-time 2511 generated call thunks in a compiler generated padding area and call 2512 patching. This increases text size by ~5%. For non affected systems 2513 this space is unused. On affected SKL systems this results in a 2514 significant performance gain over the IBRS mitigation. 2515 2516config CALL_THUNKS_DEBUG 2517 bool "Enable call thunks and call depth tracking debugging" 2518 depends on MITIGATION_CALL_DEPTH_TRACKING 2519 select FUNCTION_ALIGNMENT_32B 2520 default n 2521 help 2522 Enable call/ret counters for imbalance detection and build in 2523 a noisy dmesg about callthunks generation and call patching for 2524 trouble shooting. The debug prints need to be enabled on the 2525 kernel command line with 'debug-callthunks'. 2526 Only enable this when you are debugging call thunks as this 2527 creates a noticeable runtime overhead. If unsure say N. 2528 2529config MITIGATION_IBPB_ENTRY 2530 bool "Enable IBPB on kernel entry" 2531 depends on CPU_SUP_AMD && X86_64 2532 default y 2533 help 2534 Compile the kernel with support for the retbleed=ibpb and 2535 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations. 2536 2537config MITIGATION_IBRS_ENTRY 2538 bool "Enable IBRS on kernel entry" 2539 depends on CPU_SUP_INTEL && X86_64 2540 default y 2541 help 2542 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2543 This mitigates both spectre_v2 and retbleed at great cost to 2544 performance. 2545 2546config MITIGATION_SRSO 2547 bool "Mitigate speculative RAS overflow on AMD" 2548 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2549 default y 2550 help 2551 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2552 2553config MITIGATION_SLS 2554 bool "Mitigate Straight-Line-Speculation" 2555 depends on CC_HAS_SLS && X86_64 2556 select OBJTOOL if HAVE_OBJTOOL 2557 default n 2558 help 2559 Compile the kernel with straight-line-speculation options to guard 2560 against straight line speculation. The kernel image might be slightly 2561 larger. 2562 2563config MITIGATION_GDS 2564 bool "Mitigate Gather Data Sampling" 2565 depends on CPU_SUP_INTEL 2566 default y 2567 help 2568 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware 2569 vulnerability which allows unprivileged speculative access to data 2570 which was previously stored in vector registers. The attacker uses gather 2571 instructions to infer the stale vector register data. 2572 2573config MITIGATION_RFDS 2574 bool "RFDS Mitigation" 2575 depends on CPU_SUP_INTEL 2576 default y 2577 help 2578 Enable mitigation for Register File Data Sampling (RFDS) by default. 2579 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2580 allows unprivileged speculative access to stale data previously 2581 stored in floating point, vector and integer registers. 2582 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2583 2584config MITIGATION_SPECTRE_BHI 2585 bool "Mitigate Spectre-BHB (Branch History Injection)" 2586 depends on CPU_SUP_INTEL 2587 default y 2588 help 2589 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2590 where the branch history buffer is poisoned to speculatively steer 2591 indirect branches. 2592 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2593 2594config MITIGATION_MDS 2595 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug" 2596 depends on CPU_SUP_INTEL 2597 default y 2598 help 2599 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is 2600 a hardware vulnerability which allows unprivileged speculative access 2601 to data which is available in various CPU internal buffers. 2602 See also <file:Documentation/admin-guide/hw-vuln/mds.rst> 2603 2604config MITIGATION_TAA 2605 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug" 2606 depends on CPU_SUP_INTEL 2607 default y 2608 help 2609 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware 2610 vulnerability that allows unprivileged speculative access to data 2611 which is available in various CPU internal buffers by using 2612 asynchronous aborts within an Intel TSX transactional region. 2613 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst> 2614 2615config MITIGATION_MMIO_STALE_DATA 2616 bool "Mitigate MMIO Stale Data hardware bug" 2617 depends on CPU_SUP_INTEL 2618 default y 2619 help 2620 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO 2621 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO) 2622 vulnerabilities that can expose data. The vulnerabilities require the 2623 attacker to have access to MMIO. 2624 See also 2625 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst> 2626 2627config MITIGATION_L1TF 2628 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug" 2629 depends on CPU_SUP_INTEL 2630 default y 2631 help 2632 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a 2633 hardware vulnerability which allows unprivileged speculative access to data 2634 available in the Level 1 Data Cache. 2635 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst 2636 2637config MITIGATION_RETBLEED 2638 bool "Mitigate RETBleed hardware bug" 2639 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY 2640 default y 2641 help 2642 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution 2643 with Return Instructions) vulnerability. RETBleed is a speculative 2644 execution attack which takes advantage of microarchitectural behavior 2645 in many modern microprocessors, similar to Spectre v2. An 2646 unprivileged attacker can use these flaws to bypass conventional 2647 memory security restrictions to gain read access to privileged memory 2648 that would otherwise be inaccessible. 2649 2650config MITIGATION_SPECTRE_V1 2651 bool "Mitigate SPECTRE V1 hardware bug" 2652 default y 2653 help 2654 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a 2655 class of side channel attacks that takes advantage of speculative 2656 execution that bypasses conditional branch instructions used for 2657 memory access bounds check. 2658 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2659 2660config MITIGATION_SPECTRE_V2 2661 bool "Mitigate SPECTRE V2 hardware bug" 2662 default y 2663 help 2664 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre 2665 V2 is a class of side channel attacks that takes advantage of 2666 indirect branch predictors inside the processor. In Spectre variant 2 2667 attacks, the attacker can steer speculative indirect branches in the 2668 victim to gadget code by poisoning the branch target buffer of a CPU 2669 used for predicting indirect branch addresses. 2670 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2671 2672config MITIGATION_SRBDS 2673 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug" 2674 depends on CPU_SUP_INTEL 2675 default y 2676 help 2677 Enable mitigation for Special Register Buffer Data Sampling (SRBDS). 2678 SRBDS is a hardware vulnerability that allows Microarchitectural Data 2679 Sampling (MDS) techniques to infer values returned from special 2680 register accesses. An unprivileged user can extract values returned 2681 from RDRAND and RDSEED executed on another core or sibling thread 2682 using MDS techniques. 2683 See also 2684 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst> 2685 2686config MITIGATION_SSB 2687 bool "Mitigate Speculative Store Bypass (SSB) hardware bug" 2688 default y 2689 help 2690 Enable mitigation for Speculative Store Bypass (SSB). SSB is a 2691 hardware security vulnerability and its exploitation takes advantage 2692 of speculative execution in a similar way to the Meltdown and Spectre 2693 security vulnerabilities. 2694 2695config MITIGATION_ITS 2696 bool "Enable Indirect Target Selection mitigation" 2697 depends on CPU_SUP_INTEL && X86_64 2698 depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK 2699 select EXECMEM 2700 default y 2701 help 2702 Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in 2703 BPU on some Intel CPUs that may allow Spectre V2 style attacks. If 2704 disabled, mitigation cannot be enabled via cmdline. 2705 See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst> 2706 2707config MITIGATION_TSA 2708 bool "Mitigate Transient Scheduler Attacks" 2709 depends on CPU_SUP_AMD 2710 default y 2711 help 2712 Enable mitigation for Transient Scheduler Attacks. TSA is a hardware 2713 security vulnerability on AMD CPUs which can lead to forwarding of 2714 invalid info to subsequent instructions and thus can affect their 2715 timing and thereby cause a leakage. 2716 2717config MITIGATION_VMSCAPE 2718 bool "Mitigate VMSCAPE" 2719 depends on KVM 2720 default y 2721 help 2722 Enable mitigation for VMSCAPE attacks. VMSCAPE is a hardware security 2723 vulnerability on Intel and AMD CPUs that may allow a guest to do 2724 Spectre v2 style attacks on userspace hypervisor. 2725endif 2726 2727config ARCH_HAS_ADD_PAGES 2728 def_bool y 2729 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2730 2731menu "Power management and ACPI options" 2732 2733config ARCH_HIBERNATION_HEADER 2734 def_bool y 2735 depends on HIBERNATION 2736 2737source "kernel/power/Kconfig" 2738 2739source "drivers/acpi/Kconfig" 2740 2741config X86_APM_BOOT 2742 def_bool y 2743 depends on APM 2744 2745menuconfig APM 2746 tristate "APM (Advanced Power Management) BIOS support" 2747 depends on X86_32 && PM_SLEEP 2748 help 2749 APM is a BIOS specification for saving power using several different 2750 techniques. This is mostly useful for battery powered laptops with 2751 APM compliant BIOSes. If you say Y here, the system time will be 2752 reset after a RESUME operation, the /proc/apm device will provide 2753 battery status information, and user-space programs will receive 2754 notification of APM "events" (e.g. battery status change). 2755 2756 If you select "Y" here, you can disable actual use of the APM 2757 BIOS by passing the "apm=off" option to the kernel at boot time. 2758 2759 Note that the APM support is almost completely disabled for 2760 machines with more than one CPU. 2761 2762 In order to use APM, you will need supporting software. For location 2763 and more information, read <file:Documentation/power/apm-acpi.rst> 2764 and the Battery Powered Linux mini-HOWTO, available from 2765 <http://www.tldp.org/docs.html#howto>. 2766 2767 This driver does not spin down disk drives (see the hdparm(8) 2768 manpage ("man 8 hdparm") for that), and it doesn't turn off 2769 VESA-compliant "green" monitors. 2770 2771 Generally, if you don't have a battery in your machine, there isn't 2772 much point in using this driver and you should say N. If you get 2773 random kernel OOPSes or reboots that don't seem to be related to 2774 anything, try disabling/enabling this option (or disabling/enabling 2775 APM in your BIOS). 2776 2777 Some other things you should try when experiencing seemingly random, 2778 "weird" problems: 2779 2780 1) make sure that you have enough swap space and that it is 2781 enabled. 2782 2) pass the "idle=poll" option to the kernel 2783 3) switch on floating point emulation in the kernel and pass 2784 the "no387" option to the kernel 2785 4) pass the "floppy=nodma" option to the kernel 2786 5) pass the "mem=4M" option to the kernel (thereby disabling 2787 all but the first 4 MB of RAM) 2788 6) make sure that the CPU is not over clocked. 2789 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2790 8) disable the cache from your BIOS settings 2791 9) install a fan for the video card or exchange video RAM 2792 10) install a better fan for the CPU 2793 11) exchange RAM chips 2794 12) exchange the motherboard. 2795 2796 To compile this driver as a module, choose M here: the 2797 module will be called apm. 2798 2799if APM 2800 2801config APM_IGNORE_USER_SUSPEND 2802 bool "Ignore USER SUSPEND" 2803 help 2804 This option will ignore USER SUSPEND requests. On machines with a 2805 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2806 series notebooks, it is necessary to say Y because of a BIOS bug. 2807 2808config APM_DO_ENABLE 2809 bool "Enable PM at boot time" 2810 help 2811 Enable APM features at boot time. From page 36 of the APM BIOS 2812 specification: "When disabled, the APM BIOS does not automatically 2813 power manage devices, enter the Standby State, enter the Suspend 2814 State, or take power saving steps in response to CPU Idle calls." 2815 This driver will make CPU Idle calls when Linux is idle (unless this 2816 feature is turned off -- see "Do CPU IDLE calls", below). This 2817 should always save battery power, but more complicated APM features 2818 will be dependent on your BIOS implementation. You may need to turn 2819 this option off if your computer hangs at boot time when using APM 2820 support, or if it beeps continuously instead of suspending. Turn 2821 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2822 T400CDT. This is off by default since most machines do fine without 2823 this feature. 2824 2825config APM_CPU_IDLE 2826 depends on CPU_IDLE 2827 bool "Make CPU Idle calls when idle" 2828 help 2829 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2830 On some machines, this can activate improved power savings, such as 2831 a slowed CPU clock rate, when the machine is idle. These idle calls 2832 are made after the idle loop has run for some length of time (e.g., 2833 333 mS). On some machines, this will cause a hang at boot time or 2834 whenever the CPU becomes idle. (On machines with more than one CPU, 2835 this option does nothing.) 2836 2837config APM_DISPLAY_BLANK 2838 bool "Enable console blanking using APM" 2839 help 2840 Enable console blanking using the APM. Some laptops can use this to 2841 turn off the LCD backlight when the screen blanker of the Linux 2842 virtual console blanks the screen. Note that this is only used by 2843 the virtual console screen blanker, and won't turn off the backlight 2844 when using the X Window system. This also doesn't have anything to 2845 do with your VESA-compliant power-saving monitor. Further, this 2846 option doesn't work for all laptops -- it might not turn off your 2847 backlight at all, or it might print a lot of errors to the console, 2848 especially if you are using gpm. 2849 2850config APM_ALLOW_INTS 2851 bool "Allow interrupts during APM BIOS calls" 2852 help 2853 Normally we disable external interrupts while we are making calls to 2854 the APM BIOS as a measure to lessen the effects of a badly behaving 2855 BIOS implementation. The BIOS should reenable interrupts if it 2856 needs to. Unfortunately, some BIOSes do not -- especially those in 2857 many of the newer IBM Thinkpads. If you experience hangs when you 2858 suspend, try setting this to Y. Otherwise, say N. 2859 2860endif # APM 2861 2862source "drivers/cpufreq/Kconfig" 2863 2864source "drivers/cpuidle/Kconfig" 2865 2866source "drivers/idle/Kconfig" 2867 2868endmenu 2869 2870menu "Bus options (PCI etc.)" 2871 2872choice 2873 prompt "PCI access mode" 2874 depends on X86_32 && PCI 2875 default PCI_GOANY 2876 help 2877 On PCI systems, the BIOS can be used to detect the PCI devices and 2878 determine their configuration. However, some old PCI motherboards 2879 have BIOS bugs and may crash if this is done. Also, some embedded 2880 PCI-based systems don't have any BIOS at all. Linux can also try to 2881 detect the PCI hardware directly without using the BIOS. 2882 2883 With this option, you can specify how Linux should detect the 2884 PCI devices. If you choose "BIOS", the BIOS will be used, 2885 if you choose "Direct", the BIOS won't be used, and if you 2886 choose "MMConfig", then PCI Express MMCONFIG will be used. 2887 If you choose "Any", the kernel will try MMCONFIG, then the 2888 direct access method and falls back to the BIOS if that doesn't 2889 work. If unsure, go with the default, which is "Any". 2890 2891config PCI_GOBIOS 2892 bool "BIOS" 2893 2894config PCI_GOMMCONFIG 2895 bool "MMConfig" 2896 2897config PCI_GODIRECT 2898 bool "Direct" 2899 2900config PCI_GOOLPC 2901 bool "OLPC XO-1" 2902 depends on OLPC 2903 2904config PCI_GOANY 2905 bool "Any" 2906 2907endchoice 2908 2909config PCI_BIOS 2910 def_bool y 2911 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2912 2913# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2914config PCI_DIRECT 2915 def_bool y 2916 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2917 2918config PCI_MMCONFIG 2919 bool "Support mmconfig PCI config space access" if X86_64 2920 default y 2921 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2922 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2923 help 2924 Add support for accessing the PCI configuration space as a memory 2925 mapped area. It is the recommended method if the system supports 2926 this (it must have PCI Express and ACPI for it to be available). 2927 2928 In the unlikely case that enabling this configuration option causes 2929 problems, the mechanism can be switched off with the 'pci=nommconf' 2930 command line parameter. 2931 2932 Say N only if you are sure that your platform does not support this 2933 access method or you have problems caused by it. 2934 2935 Say Y otherwise. 2936 2937config PCI_OLPC 2938 def_bool y 2939 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2940 2941config PCI_XEN 2942 def_bool y 2943 depends on PCI && XEN 2944 2945config MMCONF_FAM10H 2946 def_bool y 2947 depends on X86_64 && PCI_MMCONFIG && ACPI 2948 2949config PCI_CNB20LE_QUIRK 2950 bool "Read PCI host bridge windows from the CNB20LE chipset" if EXPERT 2951 depends on X86_32 && PCI 2952 help 2953 Read the PCI windows out of the CNB20LE host bridge. This allows 2954 PCI hotplug to work on systems with the CNB20LE chipset which do 2955 not have ACPI. 2956 2957 The ServerWorks (later Broadcom) CNB20LE was a chipset designed 2958 most probably only for Pentium III. 2959 2960 To find out if you have such a chipset, search for a PCI device with 2961 1166:0009 PCI IDs, for example by executing 2962 lspci -nn | grep '1166:0009' 2963 The code is inactive if there is none. 2964 2965 There's no public spec for this chipset, and this functionality 2966 is known to be incomplete. 2967 2968 You should say N unless you know you need this. 2969 2970config ISA_BUS 2971 bool "ISA bus support on modern systems" if EXPERT 2972 help 2973 Expose ISA bus device drivers and options available for selection and 2974 configuration. Enable this option if your target machine has an ISA 2975 bus. ISA is an older system, displaced by PCI and newer bus 2976 architectures -- if your target machine is modern, it probably does 2977 not have an ISA bus. 2978 2979 If unsure, say N. 2980 2981# x86_64 have no ISA slots, but can have ISA-style DMA. 2982config ISA_DMA_API 2983 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2984 default y 2985 help 2986 Enables ISA-style DMA support for devices requiring such controllers. 2987 If unsure, say Y. 2988 2989if X86_32 2990 2991config ISA 2992 bool "ISA support" 2993 help 2994 Find out whether you have ISA slots on your motherboard. ISA is the 2995 name of a bus system, i.e. the way the CPU talks to the other stuff 2996 inside your box. Other bus systems are PCI, EISA, MicroChannel 2997 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2998 newer boards don't support it. If you have ISA, say Y, otherwise N. 2999 3000config SCx200 3001 tristate "NatSemi SCx200 support" 3002 help 3003 This provides basic support for National Semiconductor's 3004 (now AMD's) Geode processors. The driver probes for the 3005 PCI-IDs of several on-chip devices, so its a good dependency 3006 for other scx200_* drivers. 3007 3008 If compiled as a module, the driver is named scx200. 3009 3010config SCx200HR_TIMER 3011 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 3012 depends on SCx200 3013 default y 3014 help 3015 This driver provides a clocksource built upon the on-chip 3016 27MHz high-resolution timer. Its also a workaround for 3017 NSC Geode SC-1100's buggy TSC, which loses time when the 3018 processor goes idle (as is done by the scheduler). The 3019 other workaround is idle=poll boot option. 3020 3021config OLPC 3022 bool "One Laptop Per Child support" 3023 depends on !X86_PAE 3024 select GPIOLIB 3025 select OF 3026 select OF_PROMTREE 3027 select IRQ_DOMAIN 3028 select OLPC_EC 3029 help 3030 Add support for detecting the unique features of the OLPC 3031 XO hardware. 3032 3033config OLPC_XO1_PM 3034 bool "OLPC XO-1 Power Management" 3035 depends on OLPC && MFD_CS5535=y && PM_SLEEP 3036 help 3037 Add support for poweroff and suspend of the OLPC XO-1 laptop. 3038 3039config OLPC_XO1_RTC 3040 bool "OLPC XO-1 Real Time Clock" 3041 depends on OLPC_XO1_PM && RTC_DRV_CMOS 3042 help 3043 Add support for the XO-1 real time clock, which can be used as a 3044 programmable wakeup source. 3045 3046config OLPC_XO1_SCI 3047 bool "OLPC XO-1 SCI extras" 3048 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 3049 depends on INPUT=y 3050 select POWER_SUPPLY 3051 help 3052 Add support for SCI-based features of the OLPC XO-1 laptop: 3053 - EC-driven system wakeups 3054 - Power button 3055 - Ebook switch 3056 - Lid switch 3057 - AC adapter status updates 3058 - Battery status updates 3059 3060config OLPC_XO15_SCI 3061 bool "OLPC XO-1.5 SCI extras" 3062 depends on OLPC && ACPI 3063 select POWER_SUPPLY 3064 help 3065 Add support for SCI-based features of the OLPC XO-1.5 laptop: 3066 - EC-driven system wakeups 3067 - AC adapter status updates 3068 - Battery status updates 3069 3070config GEODE_COMMON 3071 bool 3072 3073config ALIX 3074 bool "PCEngines ALIX System Support (LED setup)" 3075 select GPIOLIB 3076 select GEODE_COMMON 3077 help 3078 This option enables system support for the PCEngines ALIX. 3079 At present this just sets up LEDs for GPIO control on 3080 ALIX2/3/6 boards. However, other system specific setup should 3081 get added here. 3082 3083 Note: You must still enable the drivers for GPIO and LED support 3084 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 3085 3086 Note: You have to set alix.force=1 for boards with Award BIOS. 3087 3088config NET5501 3089 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3090 select GPIOLIB 3091 select GEODE_COMMON 3092 help 3093 This option enables system support for the Soekris Engineering net5501. 3094 3095config GEOS 3096 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3097 select GPIOLIB 3098 select GEODE_COMMON 3099 depends on DMI 3100 help 3101 This option enables system support for the Traverse Technologies GEOS. 3102 3103config TS5500 3104 bool "Technologic Systems TS-5500 platform support" 3105 depends on MELAN 3106 select CHECK_SIGNATURE 3107 select NEW_LEDS 3108 select LEDS_CLASS 3109 help 3110 This option enables system support for the Technologic Systems TS-5500. 3111 3112endif # X86_32 3113 3114config AMD_NB 3115 def_bool y 3116 depends on AMD_NODE 3117 3118config AMD_NODE 3119 def_bool y 3120 depends on CPU_SUP_AMD && PCI 3121 3122endmenu 3123 3124menu "Binary Emulations" 3125 3126config IA32_EMULATION 3127 bool "IA32 Emulation" 3128 depends on X86_64 3129 select ARCH_WANT_OLD_COMPAT_IPC 3130 select BINFMT_ELF 3131 select COMPAT_OLD_SIGACTION 3132 help 3133 Include code to run legacy 32-bit programs under a 3134 64-bit kernel. You should likely turn this on, unless you're 3135 100% sure that you don't have any 32-bit programs left. 3136 3137config IA32_EMULATION_DEFAULT_DISABLED 3138 bool "IA32 emulation disabled by default" 3139 default n 3140 depends on IA32_EMULATION 3141 help 3142 Make IA32 emulation disabled by default. This prevents loading 32-bit 3143 processes and access to 32-bit syscalls. If unsure, leave it to its 3144 default value. 3145 3146config X86_X32_ABI 3147 bool "x32 ABI for 64-bit mode" 3148 depends on X86_64 3149 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3150 # compressed debug sections to x86_x32 properly: 3151 # https://github.com/ClangBuiltLinux/linux/issues/514 3152 # https://github.com/ClangBuiltLinux/linux/issues/1141 3153 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3154 help 3155 Include code to run binaries for the x32 native 32-bit ABI 3156 for 64-bit processors. An x32 process gets access to the 3157 full 64-bit register file and wide data path while leaving 3158 pointers at 32 bits for smaller memory footprint. 3159 3160config COMPAT_32 3161 def_bool y 3162 depends on IA32_EMULATION || X86_32 3163 select HAVE_UID16 3164 select OLD_SIGSUSPEND3 3165 3166config COMPAT 3167 def_bool y 3168 depends on IA32_EMULATION || X86_X32_ABI 3169 3170config COMPAT_FOR_U64_ALIGNMENT 3171 def_bool y 3172 depends on COMPAT 3173 3174endmenu 3175 3176config HAVE_ATOMIC_IOMAP 3177 def_bool y 3178 depends on X86_32 3179 3180source "arch/x86/kvm/Kconfig" 3181 3182source "arch/x86/Kconfig.cpufeatures" 3183 3184source "arch/x86/Kconfig.assembler" 3185