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 Note that if you say Y here and choose architecture "586" or 452 "Pentium" under "Processor family", the kernel will not work on 486 453 architectures. Similarly, multiprocessor kernels for the "PPro" 454 architecture may not work on all Pentium based boards. 455 456 People using multiprocessor machines who say Y here should also say 457 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 458 Management" code will be disabled if you say Y here. 459 460 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 461 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 462 <http://www.tldp.org/docs.html#howto>. 463 464 If you don't know what to do here, say N. 465 466config X86_X2APIC 467 bool "x2APIC interrupt controller architecture support" 468 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 469 default y 470 help 471 x2APIC is an interrupt controller architecture, a component of which 472 (the local APIC) is present in the CPU. It allows faster access to 473 the local APIC and supports a larger number of CPUs in the system 474 than the predecessors. 475 476 x2APIC was introduced in Intel CPUs around 2008 and in AMD EPYC CPUs 477 in 2019, but it can be disabled by the BIOS. It is also frequently 478 emulated in virtual machines, even when the host CPU does not support 479 it. Support in the CPU can be checked by executing 480 grep x2apic /proc/cpuinfo 481 482 If this configuration option is disabled, the kernel will boot with 483 very reduced functionality and performance on some platforms that 484 have x2APIC enabled. On the other hand, on hardware that does not 485 support x2APIC, a kernel with this option enabled will just fallback 486 to older APIC implementations. 487 488 If in doubt, say Y. 489 490config AMD_SECURE_AVIC 491 bool "AMD Secure AVIC" 492 depends on AMD_MEM_ENCRYPT && X86_X2APIC 493 help 494 Enable this to get AMD Secure AVIC support on guests that have this feature. 495 496 AMD Secure AVIC provides hardware acceleration for performance sensitive 497 APIC accesses and support for managing guest owned APIC state for SEV-SNP 498 guests. Secure AVIC does not support xAPIC mode. It has functional 499 dependency on x2apic being enabled in the guest. 500 501 If you don't know what to do here, say N. 502 503config X86_POSTED_MSI 504 bool "Enable MSI and MSI-x delivery by posted interrupts" 505 depends on X86_64 && IRQ_REMAP 506 help 507 This enables MSIs that are under interrupt remapping to be delivered as 508 posted interrupts to the host kernel. Interrupt throughput can 509 potentially be improved by coalescing CPU notifications during high 510 frequency bursts. 511 512 If you don't know what to do here, say N. 513 514config X86_MPPARSE 515 bool "Enable MPS table" if ACPI 516 default y 517 depends on X86_LOCAL_APIC 518 help 519 For old smp systems that do not have proper acpi support. Newer systems 520 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 521 522config X86_CPU_RESCTRL 523 bool "x86 CPU resource control support" 524 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 525 depends on MISC_FILESYSTEMS 526 select ARCH_HAS_CPU_RESCTRL 527 select RESCTRL_FS 528 select RESCTRL_FS_PSEUDO_LOCK 529 help 530 Enable x86 CPU resource control support. 531 532 Provide support for the allocation and monitoring of system resources 533 usage by the CPU. 534 535 Intel calls this Intel Resource Director Technology 536 (Intel(R) RDT). More information about RDT can be found in the 537 Intel x86 Architecture Software Developer Manual. 538 539 AMD calls this AMD Platform Quality of Service (AMD QoS). 540 More information about AMD QoS can be found in the AMD64 Technology 541 Platform Quality of Service Extensions manual. 542 543 Say N if unsure. 544 545config X86_CPU_RESCTRL_INTEL_AET 546 bool "Intel Application Energy Telemetry" 547 depends on X86_64 && X86_CPU_RESCTRL && CPU_SUP_INTEL && INTEL_PMT_TELEMETRY=y && INTEL_TPMI=y 548 help 549 Enable per-RMID telemetry events in resctrl. 550 551 Intel feature that collects per-RMID execution data 552 about energy consumption, measure of frequency independent 553 activity and other performance metrics. Data is aggregated 554 per package. 555 556 Say N if unsure. 557 558config X86_FRED 559 bool "Flexible Return and Event Delivery" 560 depends on X86_64 561 help 562 When enabled, try to use Flexible Return and Event Delivery 563 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 564 ring transitions and exception/interrupt handling if the 565 system supports it. 566 567config X86_EXTENDED_PLATFORM 568 bool "Support for extended (non-PC) x86 platforms" 569 default y 570 help 571 If you disable this option then the kernel will only support 572 standard PC platforms. (which covers the vast majority of 573 systems out there.) 574 575 If you enable this option then you'll be able to select support 576 for the following non-PC x86 platforms, depending on the value of 577 CONFIG_64BIT. 578 579 32-bit platforms (CONFIG_64BIT=n): 580 Goldfish (mostly Android emulator) 581 Intel CE media processor (CE4100) SoC 582 Intel Quark 583 RDC R-321x SoC 584 585 64-bit platforms (CONFIG_64BIT=y): 586 Numascale NumaChip 587 ScaleMP vSMP 588 SGI Ultraviolet 589 Merrifield/Moorefield MID devices 590 Goldfish (mostly Android emulator) 591 592 If you have one of these systems, or if you want to build a 593 generic distribution kernel, say Y here - otherwise say N. 594 595# This is an alphabetically sorted list of 64 bit extended platforms 596# Please maintain the alphabetic order if and when there are additions 597config X86_NUMACHIP 598 bool "Numascale NumaChip" 599 depends on X86_64 600 depends on X86_EXTENDED_PLATFORM 601 depends on NUMA 602 depends on SMP 603 depends on X86_X2APIC 604 depends on PCI_MMCONFIG 605 help 606 Adds support for Numascale NumaChip large-SMP systems. Needed to 607 enable more than ~168 cores. 608 If you don't have one of these, you should say N here. 609 610config X86_VSMP 611 bool "ScaleMP vSMP" 612 select HYPERVISOR_GUEST 613 select PARAVIRT 614 depends on X86_64 && PCI 615 depends on X86_EXTENDED_PLATFORM 616 depends on SMP 617 help 618 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 619 supposed to run on these EM64T-based machines. Only choose this option 620 if you have one of these machines. 621 622config X86_UV 623 bool "SGI Ultraviolet" 624 depends on X86_64 625 depends on X86_EXTENDED_PLATFORM 626 depends on NUMA 627 depends on EFI 628 depends on KEXEC_CORE 629 depends on X86_X2APIC 630 depends on PCI 631 help 632 This option is needed in order to support SGI Ultraviolet systems. 633 If you don't have one of these, you should say N here. 634 635config X86_INTEL_MID 636 bool "Intel Z34xx/Z35xx MID platform support" 637 depends on X86_EXTENDED_PLATFORM 638 depends on X86_PLATFORM_DEVICES 639 depends on PCI 640 depends on X86_64 || (EXPERT && PCI_GOANY) 641 depends on X86_IO_APIC 642 select I2C 643 select DW_APB_TIMER 644 select INTEL_SCU_PCI 645 help 646 Select to build a kernel capable of supporting 64-bit Intel MID 647 (Mobile Internet Device) platform systems which do not have 648 the PCI legacy interfaces. 649 650 The only supported devices are the 22nm Merrified (Z34xx) 651 and Moorefield (Z35xx) SoC used in the Intel Edison board and 652 a small number of Android devices such as the Asus Zenfone 2, 653 Asus FonePad 8 and Dell Venue 7. 654 655 If you are building for a PC class system or non-MID tablet 656 SoCs like Bay Trail (Z36xx/Z37xx), say N here. 657 658 Intel MID platforms are based on an Intel processor and chipset which 659 consume less power than most of the x86 derivatives. 660 661config X86_GOLDFISH 662 bool "Goldfish (Virtual Platform)" 663 depends on X86_EXTENDED_PLATFORM 664 help 665 Enable support for the Goldfish virtual platform used primarily 666 for Android development. Unless you are building for the Android 667 Goldfish emulator say N here. 668 669# Following is an alphabetically sorted list of 32 bit extended platforms 670# Please maintain the alphabetic order if and when there are additions 671 672config X86_INTEL_CE 673 bool "CE4100 TV platform" 674 depends on PCI 675 depends on PCI_GODIRECT 676 depends on X86_IO_APIC 677 depends on X86_32 678 depends on X86_EXTENDED_PLATFORM 679 select X86_REBOOTFIXUPS 680 select OF 681 select OF_EARLY_FLATTREE 682 help 683 Select for the Intel CE media processor (CE4100) SOC. 684 This option compiles in support for the CE4100 SOC for settop 685 boxes and media devices. 686 687config X86_INTEL_QUARK 688 bool "Intel Quark platform support" 689 depends on X86_32 690 depends on X86_EXTENDED_PLATFORM 691 depends on X86_PLATFORM_DEVICES 692 depends on X86_TSC 693 depends on PCI 694 depends on PCI_GOANY 695 depends on X86_IO_APIC 696 select IOSF_MBI 697 select INTEL_IMR 698 select COMMON_CLK 699 help 700 Select to include support for Quark X1000 SoC. 701 Say Y here if you have a Quark based system such as the Arduino 702 compatible Intel Galileo. 703 704config X86_RDC321X 705 bool "RDC R-321x SoC" 706 depends on X86_32 707 depends on X86_EXTENDED_PLATFORM 708 select M486 709 select X86_REBOOTFIXUPS 710 help 711 This option is needed for RDC R-321x system-on-chip, also known 712 as R-8610-(G). 713 If you don't have one of these chips, you should say N here. 714 715config X86_INTEL_LPSS 716 bool "Intel Low Power Subsystem Support" 717 depends on X86 && ACPI && PCI 718 select COMMON_CLK 719 select PINCTRL 720 select IOSF_MBI 721 help 722 Select to build support for Intel Low Power Subsystem such as 723 found on Intel Lynxpoint PCH. Selecting this option enables 724 things like clock tree (common clock framework) and pincontrol 725 which are needed by the LPSS peripheral drivers. 726 727config X86_AMD_PLATFORM_DEVICE 728 bool "AMD ACPI2Platform devices support" 729 depends on ACPI 730 select COMMON_CLK 731 select PINCTRL 732 help 733 Select to interpret AMD specific ACPI device to platform device 734 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 735 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 736 implemented under PINCTRL subsystem. 737 738config IOSF_MBI 739 tristate "Intel SoC IOSF Sideband support for SoC platforms" 740 depends on PCI 741 help 742 This option enables sideband register access support for Intel SoC 743 platforms. On these platforms the IOSF sideband is used in lieu of 744 MSR's for some register accesses, mostly but not limited to thermal 745 and power. Drivers may query the availability of this device to 746 determine if they need the sideband in order to work on these 747 platforms. The sideband is available on the following SoC products. 748 This list is not meant to be exclusive. 749 - BayTrail 750 - Braswell 751 - Quark 752 753 You should say Y if you are running a kernel on one of these SoC's. 754 755config IOSF_MBI_DEBUG 756 bool "Enable IOSF sideband access through debugfs" 757 depends on IOSF_MBI && DEBUG_FS 758 help 759 Select this option to expose the IOSF sideband access registers (MCR, 760 MDR, MCRX) through debugfs to write and read register information from 761 different units on the SoC. This is most useful for obtaining device 762 state information for debug and analysis. As this is a general access 763 mechanism, users of this option would have specific knowledge of the 764 device they want to access. 765 766 If you don't require the option or are in doubt, say N. 767 768config X86_SUPPORTS_MEMORY_FAILURE 769 def_bool y 770 # MCE code calls memory_failure(): 771 depends on X86_MCE 772 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 773 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 774 depends on X86_64 || !SPARSEMEM 775 select ARCH_SUPPORTS_MEMORY_FAILURE 776 777config X86_32_IRIS 778 tristate "Eurobraille/Iris poweroff module" 779 depends on X86_32 780 help 781 The Iris machines from EuroBraille do not have APM or ACPI support 782 to shut themselves down properly. A special I/O sequence is 783 needed to do so, which is what this module does at 784 kernel shutdown. 785 786 This is only for Iris machines from EuroBraille. 787 788 If unused, say N. 789 790config SCHED_OMIT_FRAME_POINTER 791 def_bool y 792 prompt "Single-depth WCHAN output" 793 depends on X86 794 help 795 Calculate simpler /proc/<PID>/wchan values. If this option 796 is disabled then wchan values will recurse back to the 797 caller function. This provides more accurate wchan values, 798 at the expense of slightly more scheduling overhead. 799 800 If in doubt, say "Y". 801 802menuconfig HYPERVISOR_GUEST 803 bool "Linux guest support" 804 help 805 Say Y here to enable options for running Linux under various hyper- 806 visors. This option enables basic hypervisor detection and platform 807 setup. 808 809 If you say N, all options in this submenu will be skipped and 810 disabled, and Linux guest support won't be built in. 811 812if HYPERVISOR_GUEST 813 814config PARAVIRT 815 bool "Enable paravirtualization code" 816 depends on HAVE_STATIC_CALL 817 select HAVE_PV_STEAL_CLOCK_GEN 818 help 819 This changes the kernel so it can modify itself when it is run 820 under a hypervisor, potentially improving performance significantly 821 over full virtualization. However, when run without a hypervisor 822 the kernel is theoretically slower and slightly larger. 823 824config PARAVIRT_XXL 825 bool 826 depends on X86_64 827 select ARCH_HAS_LAZY_MMU_MODE 828 829config PARAVIRT_SPINLOCKS 830 bool "Paravirtualization layer for spinlocks" 831 depends on PARAVIRT && SMP 832 help 833 Paravirtualized spinlocks allow a pvops backend to replace the 834 spinlock implementation with something virtualization-friendly 835 (for example, block the virtual CPU rather than spinning). 836 837 It has a minimal impact on native kernels and gives a nice performance 838 benefit on paravirtualized KVM / Xen kernels. 839 840 If you are unsure how to answer this question, answer Y. 841 842config X86_HV_CALLBACK_VECTOR 843 def_bool n 844 845source "arch/x86/xen/Kconfig" 846 847config KVM_GUEST 848 bool "KVM Guest support (including kvmclock)" 849 depends on PARAVIRT 850 select PARAVIRT_CLOCK 851 select ARCH_CPUIDLE_HALTPOLL 852 select X86_HV_CALLBACK_VECTOR 853 default y 854 help 855 This option enables various optimizations for running under the KVM 856 hypervisor. It includes a paravirtualized clock, so that instead 857 of relying on a PIT (or probably other) emulation by the 858 underlying device model, the host provides the guest with 859 timing infrastructure such as time of day, and system time 860 861config ARCH_CPUIDLE_HALTPOLL 862 def_bool n 863 prompt "Disable host haltpoll when loading haltpoll driver" 864 help 865 If virtualized under KVM, disable host haltpoll. 866 867config PVH 868 bool "Support for running PVH guests" 869 help 870 This option enables the PVH entry point for guest virtual machines 871 as specified in the x86/HVM direct boot ABI. 872 873config PARAVIRT_TIME_ACCOUNTING 874 bool "Paravirtual steal time accounting" 875 depends on PARAVIRT 876 help 877 Select this option to enable fine granularity task steal time 878 accounting. Time spent executing other tasks in parallel with 879 the current vCPU is discounted from the vCPU power. To account for 880 that, there can be a small performance impact. 881 882 If in doubt, say N here. 883 884config PARAVIRT_CLOCK 885 bool 886 887config JAILHOUSE_GUEST 888 bool "Jailhouse non-root cell support" 889 depends on X86_64 && PCI 890 select X86_PM_TIMER 891 help 892 This option allows to run Linux as guest in a Jailhouse non-root 893 cell. You can leave this option disabled if you only want to start 894 Jailhouse and run Linux afterwards in the root cell. 895 896config ACRN_GUEST 897 bool "ACRN Guest support" 898 depends on X86_64 899 select X86_HV_CALLBACK_VECTOR 900 help 901 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 902 a flexible, lightweight reference open-source hypervisor, built with 903 real-time and safety-criticality in mind. It is built for embedded 904 IOT with small footprint and real-time features. More details can be 905 found in https://projectacrn.org/. 906 907config BHYVE_GUEST 908 bool "Bhyve (BSD Hypervisor) Guest support" 909 depends on X86_64 910 help 911 This option allows to run Linux to recognise when it is running as a 912 guest in the Bhyve hypervisor, and to support more than 255 vCPUs when 913 when doing so. More details about Bhyve can be found at https://bhyve.org 914 and https://wiki.freebsd.org/bhyve/. 915 916config INTEL_TDX_GUEST 917 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 918 depends on X86_64 && CPU_SUP_INTEL 919 depends on X86_X2APIC 920 depends on EFI_STUB 921 depends on PARAVIRT 922 select ARCH_HAS_CC_PLATFORM 923 select X86_MEM_ENCRYPT 924 select X86_MCE 925 select UNACCEPTED_MEMORY 926 help 927 Support running as a guest under Intel TDX. Without this support, 928 the guest kernel can not boot or run under TDX. 929 TDX includes memory encryption and integrity capabilities 930 which protect the confidentiality and integrity of guest 931 memory contents and CPU state. TDX guests are protected from 932 some attacks from the VMM. 933 934endif # HYPERVISOR_GUEST 935 936source "arch/x86/Kconfig.cpu" 937 938config HPET_TIMER 939 def_bool X86_64 940 prompt "HPET Timer Support" if X86_32 941 help 942 Use the IA-PC HPET (High Precision Event Timer) to manage 943 time in preference to the PIT and RTC, if a HPET is 944 present. 945 HPET is the next generation timer replacing legacy 8254s. 946 The HPET provides a stable time base on SMP 947 systems, unlike the TSC, but it is more expensive to access, 948 as it is off-chip. The interface used is documented 949 in the HPET spec, revision 1. 950 951 You can safely choose Y here. However, HPET will only be 952 activated if the platform and the BIOS support this feature. 953 Otherwise the 8254 will be used for timing services. 954 955 Choose N to continue using the legacy 8254 timer. 956 957config HPET_EMULATE_RTC 958 def_bool y 959 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 960 961# Mark as expert because too many people got it wrong. 962# The code disables itself when not needed. 963config DMI 964 default y 965 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 966 bool "Enable DMI scanning" if EXPERT 967 help 968 Enabled scanning of DMI to identify machine quirks. Say Y 969 here unless you have verified that your setup is not 970 affected by entries in the DMI blacklist. Required by PNP 971 BIOS code. 972 973config GART_IOMMU 974 bool "Old AMD GART IOMMU support" 975 select IOMMU_HELPER 976 select SWIOTLB 977 depends on X86_64 && PCI && AMD_NB 978 help 979 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 980 GART based hardware IOMMUs. 981 982 The GART supports full DMA access for devices with 32-bit access 983 limitations, on systems with more than 3 GB. This is usually needed 984 for USB, sound, many IDE/SATA chipsets and some other devices. 985 986 Newer systems typically have a modern AMD IOMMU, supported via 987 the CONFIG_AMD_IOMMU=y config option. 988 989 In normal configurations this driver is only active when needed: 990 there's more than 3 GB of memory and the system contains a 991 32-bit limited device. 992 993 If unsure, say Y. 994 995config BOOT_VESA_SUPPORT 996 bool 997 help 998 If true, at least one selected framebuffer driver can take advantage 999 of VESA video modes set at an early boot stage via the vga= parameter. 1000 1001config MAXSMP 1002 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 1003 depends on X86_64 && SMP && DEBUG_KERNEL 1004 select CPUMASK_OFFSTACK 1005 help 1006 Enable maximum number of CPUS and NUMA Nodes for this architecture. 1007 If unsure, say N. 1008 1009# 1010# The maximum number of CPUs supported: 1011# 1012# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 1013# and which can be configured interactively in the 1014# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 1015# 1016# The ranges are different on 32-bit and 64-bit kernels, depending on 1017# hardware capabilities and scalability features of the kernel. 1018# 1019# ( If MAXSMP is enabled we just use the highest possible value and disable 1020# interactive configuration. ) 1021# 1022 1023config NR_CPUS_RANGE_BEGIN 1024 int 1025 default NR_CPUS_RANGE_END if MAXSMP 1026 default 1 if !SMP 1027 default 2 1028 1029config NR_CPUS_RANGE_END 1030 int 1031 depends on X86_32 1032 default 8 if SMP 1033 default 1 if !SMP 1034 1035config NR_CPUS_RANGE_END 1036 int 1037 depends on X86_64 1038 default 8192 if SMP && CPUMASK_OFFSTACK 1039 default 512 if SMP && !CPUMASK_OFFSTACK 1040 default 1 if !SMP 1041 1042config NR_CPUS_DEFAULT 1043 int 1044 depends on X86_32 1045 default 8 if SMP 1046 default 1 if !SMP 1047 1048config NR_CPUS_DEFAULT 1049 int 1050 depends on X86_64 1051 default 8192 if MAXSMP 1052 default 64 if SMP 1053 default 1 if !SMP 1054 1055config NR_CPUS 1056 int "Maximum number of CPUs" if SMP && !MAXSMP 1057 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1058 default NR_CPUS_DEFAULT 1059 help 1060 This allows you to specify the maximum number of CPUs which this 1061 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1062 supported value is 8192, otherwise the maximum value is 512. The 1063 minimum value which makes sense is 2. 1064 1065 This is purely to save memory: each supported CPU adds about 8KB 1066 to the kernel image. 1067 1068config SCHED_MC_PRIO 1069 bool "CPU core priorities scheduler support" 1070 depends on SCHED_MC 1071 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1072 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1073 select CPU_FREQ 1074 default y 1075 help 1076 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1077 core ordering determined at manufacturing time, which allows 1078 certain cores to reach higher turbo frequencies (when running 1079 single threaded workloads) than others. 1080 1081 Enabling this kernel feature teaches the scheduler about 1082 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1083 scheduler's CPU selection logic accordingly, so that higher 1084 overall system performance can be achieved. 1085 1086 This feature will have no effect on CPUs without this feature. 1087 1088 If unsure say Y here. 1089 1090config UP_LATE_INIT 1091 def_bool y 1092 depends on !SMP && X86_LOCAL_APIC 1093 1094config X86_UP_APIC 1095 bool "Local APIC support on uniprocessors" if !PCI_MSI 1096 default PCI_MSI 1097 depends on X86_32 && !SMP 1098 help 1099 A local APIC (Advanced Programmable Interrupt Controller) is an 1100 integrated interrupt controller in the CPU. If you have a single-CPU 1101 system which has a processor with a local APIC, you can say Y here to 1102 enable and use it. If you say Y here even though your machine doesn't 1103 have a local APIC, then the kernel will still run with no slowdown at 1104 all. The local APIC supports CPU-generated self-interrupts (timer, 1105 performance counters), and the NMI watchdog which detects hard 1106 lockups. 1107 1108config X86_UP_IOAPIC 1109 bool "IO-APIC support on uniprocessors" 1110 depends on X86_UP_APIC 1111 help 1112 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1113 SMP-capable replacement for PC-style interrupt controllers. Most 1114 SMP systems and many recent uniprocessor systems have one. 1115 1116 If you have a single-CPU system with an IO-APIC, you can say Y here 1117 to use it. If you say Y here even though your machine doesn't have 1118 an IO-APIC, then the kernel will still run with no slowdown at all. 1119 1120config X86_LOCAL_APIC 1121 def_bool y 1122 depends on X86_64 || SMP || X86_UP_APIC || PCI_MSI 1123 select IRQ_DOMAIN_HIERARCHY 1124 1125config ACPI_MADT_WAKEUP 1126 def_bool y 1127 depends on X86_64 1128 depends on ACPI 1129 depends on SMP 1130 depends on X86_LOCAL_APIC 1131 1132config X86_IO_APIC 1133 def_bool y 1134 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1135 1136config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1137 bool "Reroute for broken boot IRQs" 1138 depends on X86_IO_APIC 1139 help 1140 This option enables a workaround that fixes a source of 1141 spurious interrupts. This is recommended when threaded 1142 interrupt handling is used on systems where the generation of 1143 superfluous "boot interrupts" cannot be disabled. 1144 1145 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1146 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1147 kernel does during interrupt handling). On chipsets where this 1148 boot IRQ generation cannot be disabled, this workaround keeps 1149 the original IRQ line masked so that only the equivalent "boot 1150 IRQ" is delivered to the CPUs. The workaround also tells the 1151 kernel to set up the IRQ handler on the boot IRQ line. In this 1152 way only one interrupt is delivered to the kernel. Otherwise 1153 the spurious second interrupt may cause the kernel to bring 1154 down (vital) interrupt lines. 1155 1156 Only affects "broken" chipsets. Interrupt sharing may be 1157 increased on these systems. 1158 1159config X86_MCE 1160 bool "Machine Check / overheating reporting" 1161 select GENERIC_ALLOCATOR 1162 default y 1163 help 1164 Machine Check support allows the processor to notify the 1165 kernel if it detects a problem (e.g. overheating, data corruption). 1166 The action the kernel takes depends on the severity of the problem, 1167 ranging from warning messages to halting the machine. 1168 1169config X86_MCELOG_LEGACY 1170 bool "Support for deprecated /dev/mcelog character device" 1171 depends on X86_MCE 1172 help 1173 Enable support for /dev/mcelog which is needed by the old mcelog 1174 userspace logging daemon. Consider switching to the new generation 1175 rasdaemon solution. 1176 1177config X86_MCE_INTEL 1178 def_bool y 1179 prompt "Intel MCE features" 1180 depends on X86_MCE && X86_LOCAL_APIC 1181 help 1182 Additional support for intel specific MCE features such as 1183 the thermal monitor. 1184 1185config X86_MCE_AMD 1186 def_bool y 1187 prompt "AMD MCE features" 1188 depends on X86_MCE && X86_LOCAL_APIC 1189 help 1190 Additional support for AMD specific MCE features such as 1191 the DRAM Error Threshold. 1192 1193config X86_ANCIENT_MCE 1194 bool "Support for old Pentium 5 / WinChip machine checks" 1195 depends on X86_32 && X86_MCE 1196 help 1197 Include support for machine check handling on old Pentium 5 or WinChip 1198 systems. These typically need to be enabled explicitly on the command 1199 line. 1200 1201config X86_MCE_THRESHOLD 1202 depends on X86_MCE_AMD || X86_MCE_INTEL 1203 def_bool y 1204 1205config X86_MCE_INJECT 1206 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1207 tristate "Machine check injector support" 1208 help 1209 Provide support for injecting machine checks for testing purposes. 1210 If you don't know what a machine check is and you don't do kernel 1211 QA it is safe to say n. 1212 1213source "arch/x86/events/Kconfig" 1214 1215config X86_LEGACY_VM86 1216 bool "Legacy VM86 support" 1217 depends on X86_32 1218 help 1219 This option allows user programs to put the CPU into V8086 1220 mode, which is an 80286-era approximation of 16-bit real mode. 1221 1222 Some very old versions of X and/or vbetool require this option 1223 for user mode setting. Similarly, DOSEMU will use it if 1224 available to accelerate real mode DOS programs. However, any 1225 recent version of DOSEMU, X, or vbetool should be fully 1226 functional even without kernel VM86 support, as they will all 1227 fall back to software emulation. Nevertheless, if you are using 1228 a 16-bit DOS program where 16-bit performance matters, vm86 1229 mode might be faster than emulation and you might want to 1230 enable this option. 1231 1232 Note that any app that works on a 64-bit kernel is unlikely to 1233 need this option, as 64-bit kernels don't, and can't, support 1234 V8086 mode. This option is also unrelated to 16-bit protected 1235 mode and is not needed to run most 16-bit programs under Wine. 1236 1237 Enabling this option increases the complexity of the kernel 1238 and slows down exception handling a tiny bit. 1239 1240 If unsure, say N here. 1241 1242config VM86 1243 bool 1244 default X86_LEGACY_VM86 1245 1246config X86_16BIT 1247 bool "Enable support for 16-bit segments" if EXPERT 1248 default y 1249 depends on MODIFY_LDT_SYSCALL 1250 help 1251 This option is required by programs like Wine to run 16-bit 1252 protected mode legacy code on x86 processors. Disabling 1253 this option saves about 300 bytes on i386, or around 6K text 1254 plus 16K runtime memory on x86-64, 1255 1256config X86_ESPFIX32 1257 def_bool y 1258 depends on X86_16BIT && X86_32 1259 1260config X86_ESPFIX64 1261 def_bool y 1262 depends on X86_16BIT && X86_64 1263 1264config X86_VSYSCALL_EMULATION 1265 bool "Enable vsyscall emulation" if EXPERT 1266 default y 1267 depends on X86_64 1268 help 1269 This enables emulation of the legacy vsyscall page. Disabling 1270 it is roughly equivalent to booting with vsyscall=none, except 1271 that it will also disable the helpful warning if a program 1272 tries to use a vsyscall. With this option set to N, offending 1273 programs will just segfault, citing addresses of the form 1274 0xffffffffff600?00. 1275 1276 This option is required by many programs built before 2013, and 1277 care should be used even with newer programs if set to N. 1278 1279 Disabling this option saves about 7K of kernel size and 1280 possibly 4K of additional runtime pagetable memory. 1281 1282config X86_IOPL_IOPERM 1283 bool "IOPERM and IOPL Emulation" 1284 default y 1285 help 1286 This enables the ioperm() and iopl() syscalls which are necessary 1287 for legacy applications. 1288 1289 Legacy IOPL support is an overbroad mechanism which allows user 1290 space aside of accessing all 65536 I/O ports also to disable 1291 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1292 capabilities and permission from potentially active security 1293 modules. 1294 1295 The emulation restricts the functionality of the syscall to 1296 only allowing the full range I/O port access, but prevents the 1297 ability to disable interrupts from user space which would be 1298 granted if the hardware IOPL mechanism would be used. 1299 1300config TOSHIBA 1301 tristate "Toshiba Laptop support" 1302 depends on X86_32 1303 help 1304 This adds a driver to safely access the System Management Mode of 1305 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1306 not work on models with a Phoenix BIOS. The System Management Mode 1307 is used to set the BIOS and power saving options on Toshiba portables. 1308 1309 For information on utilities to make use of this driver see the 1310 Toshiba Linux utilities web site at: 1311 <http://www.buzzard.org.uk/toshiba/>. 1312 1313 Say Y if you intend to run this kernel on a Toshiba portable. 1314 Say N otherwise. 1315 1316config X86_REBOOTFIXUPS 1317 bool "Enable X86 board specific fixups for reboot" 1318 depends on X86_32 1319 help 1320 This enables chipset and/or board specific fixups to be done 1321 in order to get reboot to work correctly. This is only needed on 1322 some combinations of hardware and BIOS. The symptom, for which 1323 this config is intended, is when reboot ends with a stalled/hung 1324 system. 1325 1326 Currently, the only fixup is for the Geode machines using 1327 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1328 1329 Say Y if you want to enable the fixup. Currently, it's safe to 1330 enable this option even if you don't need it. 1331 Say N otherwise. 1332 1333config MICROCODE 1334 def_bool y 1335 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1336 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD 1337 1338config MICROCODE_INITRD32 1339 def_bool y 1340 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1341 1342config MICROCODE_LATE_LOADING 1343 bool "Late microcode loading (DANGEROUS)" 1344 default n 1345 depends on MICROCODE && SMP 1346 help 1347 Loading microcode late, when the system is up and executing instructions 1348 is a tricky business and should be avoided if possible. Just the sequence 1349 of synchronizing all cores and SMT threads is one fragile dance which does 1350 not guarantee that cores might not softlock after the loading. Therefore, 1351 use this at your own risk. Late loading taints the kernel unless the 1352 microcode header indicates that it is safe for late loading via the 1353 minimal revision check. This minimal revision check can be enforced on 1354 the kernel command line with "microcode=force_minrev". 1355 1356config MICROCODE_LATE_FORCE_MINREV 1357 bool "Enforce late microcode loading minimal revision check" 1358 default n 1359 depends on MICROCODE_LATE_LOADING 1360 help 1361 To prevent that users load microcode late which modifies already 1362 in use features, newer microcode patches have a minimum revision field 1363 in the microcode header, which tells the kernel which minimum 1364 revision must be active in the CPU to safely load that new microcode 1365 late into the running system. If disabled the check will not 1366 be enforced but the kernel will be tainted when the minimal 1367 revision check fails. 1368 1369 This minimal revision check can also be controlled via the 1370 "microcode=force_minrev" parameter on the kernel command line. 1371 1372 If unsure say Y. 1373 1374config MICROCODE_DBG 1375 bool "Enable microcode loader debugging" 1376 default n 1377 depends on MICROCODE 1378 help 1379 Enable code which allows to debug the microcode loader. When running 1380 in a guest the patch loading is simulated but everything else 1381 related to patch parsing and handling is done as on baremetal with 1382 the purpose of debugging solely the software side of things. On 1383 baremetal, it simply dumps additional debugging information during 1384 normal operation. 1385 1386 You almost certainly want to say n here. 1387 1388config X86_MSR 1389 tristate "/dev/cpu/*/msr - Model-specific register support" 1390 help 1391 This device gives privileged processes access to the x86 1392 Model-Specific Registers (MSRs). It is a character device with 1393 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1394 MSR accesses are directed to a specific CPU on multi-processor 1395 systems. 1396 1397config X86_CPUID 1398 tristate "/dev/cpu/*/cpuid - CPU information support" 1399 help 1400 This device gives processes access to the x86 CPUID instruction to 1401 be executed on a specific processor. It is a character device 1402 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1403 /dev/cpu/31/cpuid. 1404 1405config HIGHMEM4G 1406 bool "High Memory Support" 1407 depends on X86_32 1408 help 1409 Linux can use up to 4 Gigabytes of physical memory on x86 systems. 1410 However, the address space of 32-bit x86 processors is only 4 1411 Gigabytes large. That means that, if you have a large amount of 1412 physical memory, not all of it can be "permanently mapped" by the 1413 kernel. The physical memory that's not permanently mapped is called 1414 "high memory". 1415 1416 If you are compiling a kernel which will never run on a machine with 1417 more than 1 Gigabyte total physical RAM, answer "off" here (default 1418 choice and suitable for most users). This will result in a "3GB/1GB" 1419 split: 3GB are mapped so that each process sees a 3GB virtual memory 1420 space and the remaining part of the 4GB virtual memory space is used 1421 by the kernel to permanently map as much physical memory as 1422 possible. 1423 1424 If the machine has between 1 and 4 Gigabytes physical RAM, then 1425 answer "Y" here. 1426 1427 If unsure, say N. 1428 1429choice 1430 prompt "Memory split" if EXPERT 1431 default VMSPLIT_3G 1432 depends on X86_32 1433 help 1434 Select the desired split between kernel and user memory. 1435 1436 If the address range available to the kernel is less than the 1437 physical memory installed, the remaining memory will be available 1438 as "high memory". Accessing high memory is a little more costly 1439 than low memory, as it needs to be mapped into the kernel first. 1440 Note that increasing the kernel address space limits the range 1441 available to user programs, making the address space there 1442 tighter. Selecting anything other than the default 3G/1G split 1443 will also likely make your kernel incompatible with binary-only 1444 kernel modules. 1445 1446 If you are not absolutely sure what you are doing, leave this 1447 option alone! 1448 1449 config VMSPLIT_3G 1450 bool "3G/1G user/kernel split" 1451 config VMSPLIT_3G_OPT 1452 depends on !X86_PAE 1453 bool "3G/1G user/kernel split (for full 1G low memory)" 1454 config VMSPLIT_2G 1455 bool "2G/2G user/kernel split" 1456 config VMSPLIT_2G_OPT 1457 depends on !X86_PAE 1458 bool "2G/2G user/kernel split (for full 2G low memory)" 1459 config VMSPLIT_1G 1460 bool "1G/3G user/kernel split" 1461endchoice 1462 1463config PAGE_OFFSET 1464 hex 1465 default 0xB0000000 if VMSPLIT_3G_OPT 1466 default 0x80000000 if VMSPLIT_2G 1467 default 0x78000000 if VMSPLIT_2G_OPT 1468 default 0x40000000 if VMSPLIT_1G 1469 default 0xC0000000 1470 depends on X86_32 1471 1472config HIGHMEM 1473 def_bool HIGHMEM4G 1474 1475config X86_PAE 1476 bool "PAE (Physical Address Extension) Support" 1477 depends on X86_32 && X86_HAVE_PAE 1478 select PHYS_ADDR_T_64BIT 1479 help 1480 PAE is required for NX support, and furthermore enables 1481 larger swapspace support for non-overcommit purposes. It 1482 has the cost of more pagetable lookup overhead, and also 1483 consumes more pagetable space per process. 1484 1485config X86_DIRECT_GBPAGES 1486 def_bool y 1487 depends on X86_64 1488 help 1489 Certain kernel features effectively disable kernel 1490 linear 1 GB mappings (even if the CPU otherwise 1491 supports them), so don't confuse the user by printing 1492 that we have them enabled. 1493 1494config X86_CPA_STATISTICS 1495 bool "Enable statistic for Change Page Attribute" 1496 depends on DEBUG_FS 1497 help 1498 Expose statistics about the Change Page Attribute mechanism, which 1499 helps to determine the effectiveness of preserving large and huge 1500 page mappings when mapping protections are changed. 1501 1502config X86_MEM_ENCRYPT 1503 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1504 select DYNAMIC_PHYSICAL_MASK 1505 def_bool n 1506 1507config AMD_MEM_ENCRYPT 1508 bool "AMD Secure Memory Encryption (SME) support" 1509 depends on X86_64 && CPU_SUP_AMD 1510 depends on EFI_STUB 1511 select DMA_COHERENT_POOL 1512 select ARCH_USE_MEMREMAP_PROT 1513 select INSTRUCTION_DECODER 1514 select ARCH_HAS_CC_PLATFORM 1515 select X86_MEM_ENCRYPT 1516 select UNACCEPTED_MEMORY 1517 select CRYPTO_LIB_AESGCM 1518 help 1519 Say yes to enable support for the encryption of system memory. 1520 This requires an AMD processor that supports Secure Memory 1521 Encryption (SME). 1522 1523# Common NUMA Features 1524config NUMA 1525 bool "NUMA Memory Allocation and Scheduler Support" 1526 depends on SMP 1527 depends on X86_64 1528 select USE_PERCPU_NUMA_NODE_ID 1529 select OF_NUMA if OF 1530 help 1531 Enable NUMA (Non-Uniform Memory Access) support. 1532 1533 The kernel will try to allocate memory used by a CPU on the 1534 local memory controller of the CPU and add some more 1535 NUMA awareness to the kernel. 1536 1537 For 64-bit this is recommended if the system is Intel Core i7 1538 (or later), AMD Opteron, or EM64T NUMA. 1539 1540 Otherwise, you should say N. 1541 1542config AMD_NUMA 1543 def_bool y 1544 prompt "Old style AMD Opteron NUMA detection" 1545 depends on X86_64 && NUMA && PCI 1546 help 1547 Enable AMD NUMA node topology detection. You should say Y here if 1548 you have a multi processor AMD system. This uses an old method to 1549 read the NUMA configuration directly from the builtin Northbridge 1550 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1551 which also takes priority if both are compiled in. 1552 1553config X86_64_ACPI_NUMA 1554 def_bool y 1555 prompt "ACPI NUMA detection" 1556 depends on X86_64 && NUMA && ACPI && PCI 1557 select ACPI_NUMA 1558 help 1559 Enable ACPI SRAT based node topology detection. 1560 1561config NODES_SHIFT 1562 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1563 range 1 10 1564 default "10" if MAXSMP 1565 default "6" if X86_64 1566 default "3" 1567 depends on NUMA 1568 help 1569 Specify the maximum number of NUMA Nodes available on the target 1570 system. Increases memory reserved to accommodate various tables. 1571 1572config ARCH_FLATMEM_ENABLE 1573 def_bool y 1574 depends on X86_32 && !NUMA 1575 1576config ARCH_SPARSEMEM_ENABLE 1577 def_bool y 1578 select SPARSEMEM_STATIC if X86_32 1579 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1580 1581config ARCH_SPARSEMEM_DEFAULT 1582 def_bool X86_64 || (NUMA && X86_32) 1583 1584config ARCH_SELECT_MEMORY_MODEL 1585 def_bool y 1586 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1587 1588config ARCH_MEMORY_PROBE 1589 bool "Enable sysfs memory/probe interface" 1590 depends on MEMORY_HOTPLUG 1591 help 1592 This option enables a sysfs memory/probe interface for testing. 1593 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1594 If you are unsure how to answer this question, answer N. 1595 1596config ARCH_PROC_KCORE_TEXT 1597 def_bool y 1598 depends on X86_64 && PROC_KCORE 1599 1600config ILLEGAL_POINTER_VALUE 1601 hex 1602 default 0 if X86_32 1603 default 0xdead000000000000 if X86_64 1604 1605config X86_PMEM_LEGACY_DEVICE 1606 bool 1607 1608config X86_PMEM_LEGACY 1609 tristate "Support non-standard NVDIMMs and ADR protected memory" 1610 depends on PHYS_ADDR_T_64BIT 1611 depends on BLK_DEV 1612 select X86_PMEM_LEGACY_DEVICE 1613 select NUMA_KEEP_MEMINFO if NUMA 1614 select LIBNVDIMM 1615 help 1616 Treat memory marked using the non-standard e820 type of 12 as used 1617 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1618 The kernel will offer these regions to the 'pmem' driver so 1619 they can be used for persistent storage. 1620 1621 Say Y if unsure. 1622 1623config X86_CHECK_BIOS_CORRUPTION 1624 bool "Check for low memory corruption" 1625 help 1626 Periodically check for memory corruption in low memory, which 1627 is suspected to be caused by BIOS. Even when enabled in the 1628 configuration, it is disabled at runtime. Enable it by 1629 setting "memory_corruption_check=1" on the kernel command 1630 line. By default it scans the low 64k of memory every 60 1631 seconds; see the memory_corruption_check_size and 1632 memory_corruption_check_period parameters in 1633 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1634 1635 When enabled with the default parameters, this option has 1636 almost no overhead, as it reserves a relatively small amount 1637 of memory and scans it infrequently. It both detects corruption 1638 and prevents it from affecting the running system. 1639 1640 It is, however, intended as a diagnostic tool; if repeatable 1641 BIOS-originated corruption always affects the same memory, 1642 you can use memmap= to prevent the kernel from using that 1643 memory. 1644 1645config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1646 bool "Set the default setting of memory_corruption_check" 1647 depends on X86_CHECK_BIOS_CORRUPTION 1648 default y 1649 help 1650 Set whether the default state of memory_corruption_check is 1651 on or off. 1652 1653config MATH_EMULATION 1654 bool 1655 depends on MODIFY_LDT_SYSCALL 1656 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1657 help 1658 Linux can emulate a math coprocessor (used for floating point 1659 operations) if you don't have one. 486DX and Pentium processors have 1660 a math coprocessor built in, 486SX and 386 do not, unless you added 1661 a 487DX or 387, respectively. (The messages during boot time can 1662 give you some hints here ["man dmesg"].) Everyone needs either a 1663 coprocessor or this emulation. 1664 1665 If you don't have a math coprocessor, you need to say Y here; if you 1666 say Y here even though you have a coprocessor, the coprocessor will 1667 be used nevertheless. (This behavior can be changed with the kernel 1668 command line option "no387", which comes handy if your coprocessor 1669 is broken. Try "man bootparam" or see the documentation of your boot 1670 loader (lilo or loadlin) about how to pass options to the kernel at 1671 boot time.) This means that it is a good idea to say Y here if you 1672 intend to use this kernel on different machines. 1673 1674 More information about the internals of the Linux math coprocessor 1675 emulation can be found in <file:arch/x86/math-emu/README>. 1676 1677 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1678 kernel, it won't hurt. 1679 1680config MTRR 1681 def_bool y 1682 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1683 help 1684 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1685 the Memory Type Range Registers (MTRRs) may be used to control 1686 processor access to memory ranges. This is most useful if you have 1687 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1688 allows bus write transfers to be combined into a larger transfer 1689 before bursting over the PCI/AGP bus. This can increase performance 1690 of image write operations 2.5 times or more. Saying Y here creates a 1691 /proc/mtrr file which may be used to manipulate your processor's 1692 MTRRs. Typically the X server should use this. 1693 1694 This code has a reasonably generic interface so that similar 1695 control registers on other processors can be easily supported 1696 as well: 1697 1698 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1699 Registers (ARRs) which provide a similar functionality to MTRRs. For 1700 these, the ARRs are used to emulate the MTRRs. 1701 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1702 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1703 write-combining. All of these processors are supported by this code 1704 and it makes sense to say Y here if you have one of them. 1705 1706 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1707 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1708 can lead to all sorts of problems, so it's good to say Y here. 1709 1710 You can safely say Y even if your machine doesn't have MTRRs, you'll 1711 just add about 9 KB to your kernel. 1712 1713 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1714 1715config MTRR_SANITIZER 1716 def_bool y 1717 prompt "MTRR cleanup support" 1718 depends on MTRR 1719 help 1720 Convert MTRR layout from continuous to discrete, so X drivers can 1721 add writeback entries. 1722 1723 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1724 The largest mtrr entry size for a continuous block can be set with 1725 mtrr_chunk_size. 1726 1727 If unsure, say Y. 1728 1729config MTRR_SANITIZER_ENABLE_DEFAULT 1730 int "MTRR cleanup enable value (0-1)" 1731 range 0 1 1732 default "0" 1733 depends on MTRR_SANITIZER 1734 help 1735 Enable mtrr cleanup default value 1736 1737config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1738 int "MTRR cleanup spare reg num (0-7)" 1739 range 0 7 1740 default "1" 1741 depends on MTRR_SANITIZER 1742 help 1743 mtrr cleanup spare entries default, it can be changed via 1744 mtrr_spare_reg_nr=N on the kernel command line. 1745 1746config X86_PAT 1747 def_bool y 1748 prompt "x86 PAT support" if EXPERT 1749 depends on MTRR 1750 select ARCH_USES_PG_ARCH_2 1751 help 1752 Use PAT attributes to setup page level cache control. 1753 1754 PATs are the modern equivalents of MTRRs and are much more 1755 flexible than MTRRs. 1756 1757 Say N here if you see bootup problems (boot crash, boot hang, 1758 spontaneous reboots) or a non-working video driver. 1759 1760 If unsure, say Y. 1761 1762config X86_UMIP 1763 def_bool y 1764 prompt "User Mode Instruction Prevention" if EXPERT 1765 help 1766 User Mode Instruction Prevention (UMIP) is a security feature in 1767 some x86 processors. If enabled, a general protection fault is 1768 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1769 executed in user mode. These instructions unnecessarily expose 1770 information about the hardware state. 1771 1772 The vast majority of applications do not use these instructions. 1773 For the very few that do, software emulation is provided in 1774 specific cases in protected and virtual-8086 modes. Emulated 1775 results are dummy. 1776 1777config CC_HAS_IBT 1778 # GCC >= 9 and binutils >= 2.29 1779 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1780 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || CC_IS_CLANG) && \ 1781 $(as-instr,endbr64) 1782 1783config X86_CET 1784 def_bool n 1785 help 1786 CET features configured (Shadow stack or IBT) 1787 1788config X86_KERNEL_IBT 1789 prompt "Indirect Branch Tracking" 1790 def_bool y 1791 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1792 select OBJTOOL 1793 select X86_CET 1794 help 1795 Build the kernel with support for Indirect Branch Tracking, a 1796 hardware support course-grain forward-edge Control Flow Integrity 1797 protection. It enforces that all indirect calls must land on 1798 an ENDBR instruction, as such, the compiler will instrument the 1799 code with them to make this happen. 1800 1801 In addition to building the kernel with IBT, seal all functions that 1802 are not indirect call targets, avoiding them ever becoming one. 1803 1804 This requires LTO like objtool runs and will slow down the build. It 1805 does significantly reduce the number of ENDBR instructions in the 1806 kernel image. 1807 1808config X86_INTEL_MEMORY_PROTECTION_KEYS 1809 prompt "Memory Protection Keys" 1810 def_bool y 1811 # Note: only available in 64-bit mode 1812 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1813 select ARCH_USES_HIGH_VMA_FLAGS 1814 select ARCH_HAS_PKEYS 1815 help 1816 Memory Protection Keys provides a mechanism for enforcing 1817 page-based protections, but without requiring modification of the 1818 page tables when an application changes protection domains. 1819 1820 For details, see Documentation/core-api/protection-keys.rst 1821 1822 If unsure, say y. 1823 1824config ARCH_PKEY_BITS 1825 int 1826 default 4 1827 1828choice 1829 prompt "TSX enable mode" 1830 depends on CPU_SUP_INTEL 1831 default X86_INTEL_TSX_MODE_AUTO 1832 help 1833 Intel's TSX (Transactional Synchronization Extensions) feature 1834 allows to optimize locking protocols through lock elision which 1835 can lead to a noticeable performance boost. 1836 1837 On the other hand it has been shown that TSX can be exploited 1838 to form side channel attacks (e.g. TAA) and chances are there 1839 will be more of those attacks discovered in the future. 1840 1841 Therefore TSX is not enabled by default (aka tsx=off). An admin 1842 might override this decision by tsx=on the command line parameter. 1843 Even with TSX enabled, the kernel will attempt to enable the best 1844 possible TAA mitigation setting depending on the microcode available 1845 for the particular machine. 1846 1847 This option allows to set the default tsx mode between tsx=on, =off 1848 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1849 details. 1850 1851 Say off if not sure, auto if TSX is in use but it should be used on safe 1852 platforms or on if TSX is in use and the security aspect of tsx is not 1853 relevant. 1854 1855config X86_INTEL_TSX_MODE_OFF 1856 bool "off" 1857 help 1858 TSX is disabled if possible - equals to tsx=off command line parameter. 1859 1860config X86_INTEL_TSX_MODE_ON 1861 bool "on" 1862 help 1863 TSX is always enabled on TSX capable HW - equals the tsx=on command 1864 line parameter. 1865 1866config X86_INTEL_TSX_MODE_AUTO 1867 bool "auto" 1868 help 1869 TSX is enabled on TSX capable HW that is believed to be safe against 1870 side channel attacks- equals the tsx=auto command line parameter. 1871endchoice 1872 1873config X86_SGX 1874 bool "Software Guard eXtensions (SGX)" 1875 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1876 select CRYPTO_LIB_SHA256 1877 select MMU_NOTIFIER 1878 select NUMA_KEEP_MEMINFO if NUMA 1879 select XARRAY_MULTI 1880 help 1881 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1882 that can be used by applications to set aside private regions of code 1883 and data, referred to as enclaves. An enclave's private memory can 1884 only be accessed by code running within the enclave. Accesses from 1885 outside the enclave, including other enclaves, are disallowed by 1886 hardware. 1887 1888 If unsure, say N. 1889 1890config X86_USER_SHADOW_STACK 1891 bool "X86 userspace shadow stack" 1892 depends on AS_WRUSS 1893 depends on X86_64 1894 select ARCH_USES_HIGH_VMA_FLAGS 1895 select ARCH_HAS_USER_SHADOW_STACK 1896 select X86_CET 1897 help 1898 Shadow stack protection is a hardware feature that detects function 1899 return address corruption. This helps mitigate ROP attacks. 1900 Applications must be enabled to use it, and old userspace does not 1901 get protection "for free". 1902 1903 CPUs supporting shadow stacks were first released in 2020. 1904 1905 See Documentation/arch/x86/shstk.rst for more information. 1906 1907 If unsure, say N. 1908 1909config INTEL_TDX_HOST 1910 bool "Intel Trust Domain Extensions (TDX) host support" 1911 depends on CPU_SUP_INTEL 1912 depends on X86_64 1913 depends on KVM_INTEL 1914 depends on X86_X2APIC 1915 select ARCH_KEEP_MEMBLOCK 1916 depends on CONTIG_ALLOC 1917 depends on X86_MCE 1918 help 1919 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1920 host and certain physical attacks. This option enables necessary TDX 1921 support in the host kernel to run confidential VMs. 1922 1923 If unsure, say N. 1924 1925config EFI 1926 bool "EFI runtime service support" 1927 depends on ACPI 1928 select UCS2_STRING 1929 select EFI_RUNTIME_WRAPPERS 1930 select ARCH_USE_MEMREMAP_PROT 1931 select EFI_RUNTIME_MAP if KEXEC_CORE 1932 help 1933 This enables the kernel to use EFI runtime services that are 1934 available (such as the EFI variable services). 1935 1936 This option is only useful on systems that have EFI firmware. 1937 In addition, you should use the latest ELILO loader available 1938 at <http://elilo.sourceforge.net> in order to take advantage 1939 of EFI runtime services. However, even with this option, the 1940 resultant kernel should continue to boot on existing non-EFI 1941 platforms. 1942 1943config EFI_STUB 1944 bool "EFI stub support" 1945 depends on EFI 1946 select RELOCATABLE 1947 help 1948 This kernel feature allows a bzImage to be loaded directly 1949 by EFI firmware without the use of a bootloader. 1950 1951 See Documentation/admin-guide/efi-stub.rst for more information. 1952 1953config EFI_HANDOVER_PROTOCOL 1954 bool "EFI handover protocol (DEPRECATED)" 1955 depends on EFI_STUB 1956 default y 1957 help 1958 Select this in order to include support for the deprecated EFI 1959 handover protocol, which defines alternative entry points into the 1960 EFI stub. This is a practice that has no basis in the UEFI 1961 specification, and requires a priori knowledge on the part of the 1962 bootloader about Linux/x86 specific ways of passing the command line 1963 and initrd, and where in memory those assets may be loaded. 1964 1965 If in doubt, say Y. Even though the corresponding support is not 1966 present in upstream GRUB or other bootloaders, most distros build 1967 GRUB with numerous downstream patches applied, and may rely on the 1968 handover protocol as as result. 1969 1970config EFI_MIXED 1971 bool "EFI mixed-mode support" 1972 depends on EFI_STUB && X86_64 1973 help 1974 Enabling this feature allows a 64-bit kernel to be booted 1975 on a 32-bit firmware, provided that your CPU supports 64-bit 1976 mode. 1977 1978 Note that it is not possible to boot a mixed-mode enabled 1979 kernel via the EFI boot stub - a bootloader that supports 1980 the EFI handover protocol must be used. 1981 1982 If unsure, say N. 1983 1984config EFI_RUNTIME_MAP 1985 bool "Export EFI runtime maps to sysfs" if EXPERT 1986 depends on EFI 1987 help 1988 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 1989 That memory map is required by the 2nd kernel to set up EFI virtual 1990 mappings after kexec, but can also be used for debugging purposes. 1991 1992 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 1993 1994source "kernel/Kconfig.hz" 1995 1996config ARCH_SUPPORTS_KEXEC 1997 def_bool y 1998 1999config ARCH_SUPPORTS_KEXEC_FILE 2000 def_bool X86_64 2001 2002config ARCH_SELECTS_KEXEC_FILE 2003 def_bool y 2004 depends on KEXEC_FILE 2005 select HAVE_IMA_KEXEC if IMA 2006 2007config ARCH_SUPPORTS_KEXEC_PURGATORY 2008 def_bool y 2009 2010config ARCH_SUPPORTS_KEXEC_SIG 2011 def_bool y 2012 2013config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2014 def_bool y 2015 2016config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2017 def_bool y 2018 2019config ARCH_SUPPORTS_KEXEC_JUMP 2020 def_bool y 2021 2022config ARCH_SUPPORTS_KEXEC_HANDOVER 2023 def_bool X86_64 2024 2025config ARCH_SUPPORTS_CRASH_DUMP 2026 def_bool X86_64 || (X86_32 && HIGHMEM) 2027 2028config ARCH_DEFAULT_CRASH_DUMP 2029 def_bool y 2030 2031config ARCH_SUPPORTS_CRASH_HOTPLUG 2032 def_bool y 2033 2034config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2035 def_bool CRASH_RESERVE 2036 2037config PHYSICAL_START 2038 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2039 default "0x1000000" 2040 help 2041 This gives the physical address where the kernel is loaded. 2042 2043 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2044 will decompress itself to above physical address and run from there. 2045 Otherwise, bzImage will run from the address where it has been loaded 2046 by the boot loader. The only exception is if it is loaded below the 2047 above physical address, in which case it will relocate itself there. 2048 2049 In normal kdump cases one does not have to set/change this option 2050 as now bzImage can be compiled as a completely relocatable image 2051 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2052 address. This option is mainly useful for the folks who don't want 2053 to use a bzImage for capturing the crash dump and want to use a 2054 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2055 to be specifically compiled to run from a specific memory area 2056 (normally a reserved region) and this option comes handy. 2057 2058 So if you are using bzImage for capturing the crash dump, 2059 leave the value here unchanged to 0x1000000 and set 2060 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2061 for capturing the crash dump change this value to start of 2062 the reserved region. In other words, it can be set based on 2063 the "X" value as specified in the "crashkernel=YM@XM" 2064 command line boot parameter passed to the panic-ed 2065 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2066 for more details about crash dumps. 2067 2068 Usage of bzImage for capturing the crash dump is recommended as 2069 one does not have to build two kernels. Same kernel can be used 2070 as production kernel and capture kernel. Above option should have 2071 gone away after relocatable bzImage support is introduced. But it 2072 is present because there are users out there who continue to use 2073 vmlinux for dump capture. This option should go away down the 2074 line. 2075 2076 Don't change this unless you know what you are doing. 2077 2078config RELOCATABLE 2079 bool "Build a relocatable kernel" 2080 default y 2081 help 2082 This builds a kernel image that retains relocation information 2083 so it can be loaded someplace besides the default 1MB. 2084 The relocations tend to make the kernel binary about 10% larger, 2085 but are discarded at runtime. 2086 2087 One use is for the kexec on panic case where the recovery kernel 2088 must live at a different physical address than the primary 2089 kernel. 2090 2091 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2092 it has been loaded at and the compile time physical address 2093 (CONFIG_PHYSICAL_START) is used as the minimum location. 2094 2095config RANDOMIZE_BASE 2096 bool "Randomize the address of the kernel image (KASLR)" 2097 depends on RELOCATABLE 2098 default y 2099 help 2100 In support of Kernel Address Space Layout Randomization (KASLR), 2101 this randomizes the physical address at which the kernel image 2102 is decompressed and the virtual address where the kernel 2103 image is mapped, as a security feature that deters exploit 2104 attempts relying on knowledge of the location of kernel 2105 code internals. 2106 2107 On 64-bit, the kernel physical and virtual addresses are 2108 randomized separately. The physical address will be anywhere 2109 between 16MB and the top of physical memory (up to 64TB). The 2110 virtual address will be randomized from 16MB up to 1GB (9 bits 2111 of entropy). Note that this also reduces the memory space 2112 available to kernel modules from 1.5GB to 1GB. 2113 2114 On 32-bit, the kernel physical and virtual addresses are 2115 randomized together. They will be randomized from 16MB up to 2116 512MB (8 bits of entropy). 2117 2118 Entropy is generated using the RDRAND instruction if it is 2119 supported. If RDTSC is supported, its value is mixed into 2120 the entropy pool as well. If neither RDRAND nor RDTSC are 2121 supported, then entropy is read from the i8254 timer. The 2122 usable entropy is limited by the kernel being built using 2123 2GB addressing, and that PHYSICAL_ALIGN must be at a 2124 minimum of 2MB. As a result, only 10 bits of entropy are 2125 theoretically possible, but the implementations are further 2126 limited due to memory layouts. 2127 2128 If unsure, say Y. 2129 2130# Relocation on x86 needs some additional build support 2131config X86_NEED_RELOCS 2132 def_bool y 2133 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2134 select ARCH_VMLINUX_NEEDS_RELOCS 2135 2136config PHYSICAL_ALIGN 2137 hex "Alignment value to which kernel should be aligned" 2138 default "0x200000" 2139 range 0x2000 0x1000000 if X86_32 2140 range 0x200000 0x1000000 if X86_64 2141 help 2142 This value puts the alignment restrictions on physical address 2143 where kernel is loaded and run from. Kernel is compiled for an 2144 address which meets above alignment restriction. 2145 2146 If bootloader loads the kernel at a non-aligned address and 2147 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2148 address aligned to above value and run from there. 2149 2150 If bootloader loads the kernel at a non-aligned address and 2151 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2152 load address and decompress itself to the address it has been 2153 compiled for and run from there. The address for which kernel is 2154 compiled already meets above alignment restrictions. Hence the 2155 end result is that kernel runs from a physical address meeting 2156 above alignment restrictions. 2157 2158 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2159 this value must be a multiple of 0x200000. 2160 2161 Don't change this unless you know what you are doing. 2162 2163config RANDOMIZE_MEMORY 2164 bool "Randomize the kernel memory sections" 2165 depends on X86_64 2166 depends on RANDOMIZE_BASE 2167 default RANDOMIZE_BASE 2168 help 2169 Randomizes the base virtual address of kernel memory sections 2170 (physical memory mapping, vmalloc & vmemmap). This security feature 2171 makes exploits relying on predictable memory locations less reliable. 2172 2173 The order of allocations remains unchanged. Entropy is generated in 2174 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2175 configuration have in average 30,000 different possible virtual 2176 addresses for each memory section. 2177 2178 If unsure, say Y. 2179 2180config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2181 hex "Physical memory mapping padding" if EXPERT 2182 depends on RANDOMIZE_MEMORY 2183 default "0xa" if MEMORY_HOTPLUG 2184 default "0x0" 2185 range 0x1 0x40 if MEMORY_HOTPLUG 2186 range 0x0 0x40 2187 help 2188 Define the padding in terabytes added to the existing physical 2189 memory size during kernel memory randomization. It is useful 2190 for memory hotplug support but reduces the entropy available for 2191 address randomization. 2192 2193 If unsure, leave at the default value. 2194 2195config ADDRESS_MASKING 2196 bool "Linear Address Masking support" 2197 depends on X86_64 2198 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2199 help 2200 Linear Address Masking (LAM) modifies the checking that is applied 2201 to 64-bit linear addresses, allowing software to use of the 2202 untranslated address bits for metadata. 2203 2204 The capability can be used for efficient address sanitizers (ASAN) 2205 implementation and for optimizations in JITs. 2206 2207config HOTPLUG_CPU 2208 def_bool y 2209 depends on SMP 2210 2211config COMPAT_VDSO 2212 def_bool n 2213 prompt "Workaround for glibc 2.3.2 / 2.3.3 (released in year 2003/2004)" 2214 depends on COMPAT_32 2215 help 2216 Certain buggy versions of glibc will crash if they are 2217 presented with a 32-bit vDSO that is not mapped at the address 2218 indicated in its segment table. 2219 2220 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2221 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2222 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2223 the only released version with the bug, but OpenSUSE 9 2224 contains a buggy "glibc 2.3.2". 2225 2226 The symptom of the bug is that everything crashes on startup, saying: 2227 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2228 2229 Saying Y here changes the default value of the vdso32 boot 2230 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2231 This works around the glibc bug but hurts performance. 2232 2233 If unsure, say N: if you are compiling your own kernel, you 2234 are unlikely to be using a buggy version of glibc. 2235 2236choice 2237 prompt "vsyscall table for legacy applications" 2238 depends on X86_64 2239 default LEGACY_VSYSCALL_XONLY 2240 help 2241 Legacy user code that does not know how to find the vDSO expects 2242 to be able to issue three syscalls by calling fixed addresses in 2243 kernel space. Since this location is not randomized with ASLR, 2244 it can be used to assist security vulnerability exploitation. 2245 2246 This setting can be changed at boot time via the kernel command 2247 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2248 is deprecated and can only be enabled using the kernel command 2249 line. 2250 2251 On a system with recent enough glibc (2.14 or newer) and no 2252 static binaries, you can say None without a performance penalty 2253 to improve security. 2254 2255 If unsure, select "Emulate execution only". 2256 2257 config LEGACY_VSYSCALL_XONLY 2258 bool "Emulate execution only" 2259 help 2260 The kernel traps and emulates calls into the fixed vsyscall 2261 address mapping and does not allow reads. This 2262 configuration is recommended when userspace might use the 2263 legacy vsyscall area but support for legacy binary 2264 instrumentation of legacy code is not needed. It mitigates 2265 certain uses of the vsyscall area as an ASLR-bypassing 2266 buffer. 2267 2268 config LEGACY_VSYSCALL_NONE 2269 bool "None" 2270 help 2271 There will be no vsyscall mapping at all. This will 2272 eliminate any risk of ASLR bypass due to the vsyscall 2273 fixed address mapping. Attempts to use the vsyscalls 2274 will be reported to dmesg, so that either old or 2275 malicious userspace programs can be identified. 2276 2277endchoice 2278 2279config CMDLINE_BOOL 2280 bool "Built-in kernel command line" 2281 help 2282 Allow for specifying boot arguments to the kernel at 2283 build time. On some systems (e.g. embedded ones), it is 2284 necessary or convenient to provide some or all of the 2285 kernel boot arguments with the kernel itself (that is, 2286 to not rely on the boot loader to provide them.) 2287 2288 To compile command line arguments into the kernel, 2289 set this option to 'Y', then fill in the 2290 boot arguments in CONFIG_CMDLINE. 2291 2292 Systems with fully functional boot loaders (i.e. non-embedded) 2293 should leave this option set to 'N'. 2294 2295config CMDLINE 2296 string "Built-in kernel command string" 2297 depends on CMDLINE_BOOL 2298 default "" 2299 help 2300 Enter arguments here that should be compiled into the kernel 2301 image and used at boot time. If the boot loader provides a 2302 command line at boot time, it is appended to this string to 2303 form the full kernel command line, when the system boots. 2304 2305 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2306 change this behavior. 2307 2308 In most cases, the command line (whether built-in or provided 2309 by the boot loader) should specify the device for the root 2310 file system. 2311 2312config CMDLINE_OVERRIDE 2313 bool "Built-in command line overrides boot loader arguments" 2314 depends on CMDLINE_BOOL && CMDLINE != "" 2315 help 2316 Set this option to 'Y' to have the kernel ignore the boot loader 2317 command line, and use ONLY the built-in command line. 2318 2319 This is used to work around broken boot loaders. This should 2320 be set to 'N' under normal conditions. 2321 2322config MODIFY_LDT_SYSCALL 2323 bool "Enable the LDT (local descriptor table)" if EXPERT 2324 default y 2325 help 2326 Linux can allow user programs to install a per-process x86 2327 Local Descriptor Table (LDT) using the modify_ldt(2) system 2328 call. This is required to run 16-bit or segmented code such as 2329 DOSEMU or some Wine programs. It is also used by some very old 2330 threading libraries. 2331 2332 Enabling this feature adds a small amount of overhead to 2333 context switches and increases the low-level kernel attack 2334 surface. Disabling it removes the modify_ldt(2) system call. 2335 2336 Saying 'N' here may make sense for embedded or server kernels. 2337 2338config STRICT_SIGALTSTACK_SIZE 2339 bool "Enforce strict size checking for sigaltstack" 2340 depends on DYNAMIC_SIGFRAME 2341 help 2342 For historical reasons MINSIGSTKSZ is a constant which became 2343 already too small with AVX512 support. Add a mechanism to 2344 enforce strict checking of the sigaltstack size against the 2345 real size of the FPU frame. This option enables the check 2346 by default. It can also be controlled via the kernel command 2347 line option 'strict_sas_size' independent of this config 2348 switch. Enabling it might break existing applications which 2349 allocate a too small sigaltstack but 'work' because they 2350 never get a signal delivered. 2351 2352 Say 'N' unless you want to really enforce this check. 2353 2354config CFI_AUTO_DEFAULT 2355 bool "Attempt to use FineIBT by default at boot time" 2356 depends on FINEIBT 2357 depends on !RUST || RUSTC_VERSION >= 108800 2358 default y 2359 help 2360 Attempt to use FineIBT by default at boot time. If enabled, 2361 this is the same as booting with "cfi=auto". If disabled, 2362 this is the same as booting with "cfi=kcfi". 2363 2364source "kernel/livepatch/Kconfig" 2365 2366config X86_BUS_LOCK_DETECT 2367 bool "Split Lock Detect and Bus Lock Detect support" 2368 depends on CPU_SUP_INTEL || CPU_SUP_AMD 2369 default y 2370 help 2371 Enable Split Lock Detect and Bus Lock Detect functionalities. 2372 See <file:Documentation/arch/x86/buslock.rst> for more information. 2373 2374endmenu 2375 2376config CC_HAS_NAMED_AS 2377 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null) 2378 depends on CC_IS_GCC 2379 2380# 2381# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN) 2382# are incompatible with named address spaces with GCC < 13.3 2383# (see GCC PR sanitizer/111736 and also PR sanitizer/115172). 2384# 2385 2386config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2387 def_bool y 2388 depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300 2389 depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200 2390 2391config USE_X86_SEG_SUPPORT 2392 def_bool CC_HAS_NAMED_AS 2393 depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS 2394 2395config CC_HAS_SLS 2396 def_bool $(cc-option,-mharden-sls=all) 2397 2398config CC_HAS_RETURN_THUNK 2399 def_bool $(cc-option,-mfunction-return=thunk-extern) 2400 2401config CC_HAS_ENTRY_PADDING 2402 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2403 2404config CC_HAS_KCFI_ARITY 2405 def_bool $(cc-option,-fsanitize=kcfi -fsanitize-kcfi-arity) 2406 depends on CC_IS_CLANG && !RUST 2407 2408config FUNCTION_PADDING_CFI 2409 int 2410 default 59 if FUNCTION_ALIGNMENT_64B 2411 default 27 if FUNCTION_ALIGNMENT_32B 2412 default 11 if FUNCTION_ALIGNMENT_16B 2413 default 3 if FUNCTION_ALIGNMENT_8B 2414 default 0 2415 2416# Basically: FUNCTION_ALIGNMENT - 5*CFI 2417# except Kconfig can't do arithmetic :/ 2418config FUNCTION_PADDING_BYTES 2419 int 2420 default FUNCTION_PADDING_CFI if CFI 2421 default FUNCTION_ALIGNMENT 2422 2423config CALL_PADDING 2424 def_bool n 2425 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2426 select FUNCTION_ALIGNMENT_16B 2427 2428config FINEIBT 2429 def_bool y 2430 depends on X86_KERNEL_IBT && CFI && MITIGATION_RETPOLINE 2431 select CALL_PADDING 2432 2433config FINEIBT_BHI 2434 def_bool y 2435 depends on FINEIBT && CC_HAS_KCFI_ARITY 2436 2437config HAVE_CALL_THUNKS 2438 def_bool y 2439 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2440 2441config CALL_THUNKS 2442 def_bool n 2443 select CALL_PADDING 2444 2445config PREFIX_SYMBOLS 2446 def_bool y 2447 depends on CALL_PADDING && !CFI 2448 2449menuconfig CPU_MITIGATIONS 2450 bool "Mitigations for CPU vulnerabilities" 2451 default y 2452 help 2453 Say Y here to enable options which enable mitigations for hardware 2454 vulnerabilities (usually related to speculative execution). 2455 Mitigations can be disabled or restricted to SMT systems at runtime 2456 via the "mitigations" kernel parameter. 2457 2458 If you say N, all mitigations will be disabled. This CANNOT be 2459 overridden at runtime. 2460 2461 Say 'Y', unless you really know what you are doing. 2462 2463if CPU_MITIGATIONS 2464 2465config MITIGATION_PAGE_TABLE_ISOLATION 2466 bool "Remove the kernel mapping in user mode" 2467 default y 2468 depends on (X86_64 || X86_PAE) 2469 help 2470 This feature reduces the number of hardware side channels by 2471 ensuring that the majority of kernel addresses are not mapped 2472 into userspace. 2473 2474 See Documentation/arch/x86/pti.rst for more details. 2475 2476config MITIGATION_RETPOLINE 2477 bool "Avoid speculative indirect branches in kernel" 2478 select OBJTOOL if HAVE_OBJTOOL 2479 default y 2480 help 2481 Compile kernel with the retpoline compiler options to guard against 2482 kernel-to-user data leaks by avoiding speculative indirect 2483 branches. Requires a compiler with -mindirect-branch=thunk-extern 2484 support for full protection. The kernel may run slower. 2485 2486config MITIGATION_RETHUNK 2487 bool "Enable return-thunks" 2488 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2489 select OBJTOOL if HAVE_OBJTOOL 2490 default y if X86_64 2491 help 2492 Compile the kernel with the return-thunks compiler option to guard 2493 against kernel-to-user data leaks by avoiding return speculation. 2494 Requires a compiler with -mfunction-return=thunk-extern 2495 support for full protection. The kernel may run slower. 2496 2497config MITIGATION_UNRET_ENTRY 2498 bool "Enable UNRET on kernel entry" 2499 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2500 default y 2501 help 2502 Compile the kernel with support for the retbleed=unret mitigation. 2503 2504config MITIGATION_CALL_DEPTH_TRACKING 2505 bool "Mitigate RSB underflow with call depth tracking" 2506 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2507 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2508 select CALL_THUNKS 2509 default y 2510 help 2511 Compile the kernel with call depth tracking to mitigate the Intel 2512 SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off 2513 by default and needs to be enabled on the kernel command line via the 2514 retbleed=stuff option. For non-affected systems the overhead of this 2515 option is marginal as the call depth tracking is using run-time 2516 generated call thunks in a compiler generated padding area and call 2517 patching. This increases text size by ~5%. For non affected systems 2518 this space is unused. On affected SKL systems this results in a 2519 significant performance gain over the IBRS mitigation. 2520 2521config CALL_THUNKS_DEBUG 2522 bool "Enable call thunks and call depth tracking debugging" 2523 depends on MITIGATION_CALL_DEPTH_TRACKING 2524 select FUNCTION_ALIGNMENT_32B 2525 default n 2526 help 2527 Enable call/ret counters for imbalance detection and build in 2528 a noisy dmesg about callthunks generation and call patching for 2529 trouble shooting. The debug prints need to be enabled on the 2530 kernel command line with 'debug-callthunks'. 2531 Only enable this when you are debugging call thunks as this 2532 creates a noticeable runtime overhead. If unsure say N. 2533 2534config MITIGATION_IBPB_ENTRY 2535 bool "Enable IBPB on kernel entry" 2536 depends on CPU_SUP_AMD && X86_64 2537 default y 2538 help 2539 Compile the kernel with support for the retbleed=ibpb and 2540 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations. 2541 2542config MITIGATION_IBRS_ENTRY 2543 bool "Enable IBRS on kernel entry" 2544 depends on CPU_SUP_INTEL && X86_64 2545 default y 2546 help 2547 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2548 This mitigates both spectre_v2 and retbleed at great cost to 2549 performance. 2550 2551config MITIGATION_SRSO 2552 bool "Mitigate speculative RAS overflow on AMD" 2553 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2554 default y 2555 help 2556 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2557 2558config MITIGATION_SLS 2559 bool "Mitigate Straight-Line-Speculation" 2560 depends on CC_HAS_SLS && X86_64 2561 select OBJTOOL if HAVE_OBJTOOL 2562 default n 2563 help 2564 Compile the kernel with straight-line-speculation options to guard 2565 against straight line speculation. The kernel image might be slightly 2566 larger. 2567 2568config MITIGATION_GDS 2569 bool "Mitigate Gather Data Sampling" 2570 depends on CPU_SUP_INTEL 2571 default y 2572 help 2573 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware 2574 vulnerability which allows unprivileged speculative access to data 2575 which was previously stored in vector registers. The attacker uses gather 2576 instructions to infer the stale vector register data. 2577 2578config MITIGATION_RFDS 2579 bool "RFDS Mitigation" 2580 depends on CPU_SUP_INTEL 2581 default y 2582 help 2583 Enable mitigation for Register File Data Sampling (RFDS) by default. 2584 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2585 allows unprivileged speculative access to stale data previously 2586 stored in floating point, vector and integer registers. 2587 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2588 2589config MITIGATION_SPECTRE_BHI 2590 bool "Mitigate Spectre-BHB (Branch History Injection)" 2591 depends on CPU_SUP_INTEL 2592 default y 2593 help 2594 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2595 where the branch history buffer is poisoned to speculatively steer 2596 indirect branches. 2597 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2598 2599config MITIGATION_MDS 2600 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug" 2601 depends on CPU_SUP_INTEL 2602 default y 2603 help 2604 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is 2605 a hardware vulnerability which allows unprivileged speculative access 2606 to data which is available in various CPU internal buffers. 2607 See also <file:Documentation/admin-guide/hw-vuln/mds.rst> 2608 2609config MITIGATION_TAA 2610 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug" 2611 depends on CPU_SUP_INTEL 2612 default y 2613 help 2614 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware 2615 vulnerability that allows unprivileged speculative access to data 2616 which is available in various CPU internal buffers by using 2617 asynchronous aborts within an Intel TSX transactional region. 2618 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst> 2619 2620config MITIGATION_MMIO_STALE_DATA 2621 bool "Mitigate MMIO Stale Data hardware bug" 2622 depends on CPU_SUP_INTEL 2623 default y 2624 help 2625 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO 2626 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO) 2627 vulnerabilities that can expose data. The vulnerabilities require the 2628 attacker to have access to MMIO. 2629 See also 2630 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst> 2631 2632config MITIGATION_L1TF 2633 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug" 2634 depends on CPU_SUP_INTEL 2635 default y 2636 help 2637 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a 2638 hardware vulnerability which allows unprivileged speculative access to data 2639 available in the Level 1 Data Cache. 2640 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst 2641 2642config MITIGATION_RETBLEED 2643 bool "Mitigate RETBleed hardware bug" 2644 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY 2645 default y 2646 help 2647 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution 2648 with Return Instructions) vulnerability. RETBleed is a speculative 2649 execution attack which takes advantage of microarchitectural behavior 2650 in many modern microprocessors, similar to Spectre v2. An 2651 unprivileged attacker can use these flaws to bypass conventional 2652 memory security restrictions to gain read access to privileged memory 2653 that would otherwise be inaccessible. 2654 2655config MITIGATION_SPECTRE_V1 2656 bool "Mitigate SPECTRE V1 hardware bug" 2657 default y 2658 help 2659 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a 2660 class of side channel attacks that takes advantage of speculative 2661 execution that bypasses conditional branch instructions used for 2662 memory access bounds check. 2663 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2664 2665config MITIGATION_SPECTRE_V2 2666 bool "Mitigate SPECTRE V2 hardware bug" 2667 default y 2668 help 2669 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre 2670 V2 is a class of side channel attacks that takes advantage of 2671 indirect branch predictors inside the processor. In Spectre variant 2 2672 attacks, the attacker can steer speculative indirect branches in the 2673 victim to gadget code by poisoning the branch target buffer of a CPU 2674 used for predicting indirect branch addresses. 2675 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2676 2677config MITIGATION_SRBDS 2678 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug" 2679 depends on CPU_SUP_INTEL 2680 default y 2681 help 2682 Enable mitigation for Special Register Buffer Data Sampling (SRBDS). 2683 SRBDS is a hardware vulnerability that allows Microarchitectural Data 2684 Sampling (MDS) techniques to infer values returned from special 2685 register accesses. An unprivileged user can extract values returned 2686 from RDRAND and RDSEED executed on another core or sibling thread 2687 using MDS techniques. 2688 See also 2689 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst> 2690 2691config MITIGATION_SSB 2692 bool "Mitigate Speculative Store Bypass (SSB) hardware bug" 2693 default y 2694 help 2695 Enable mitigation for Speculative Store Bypass (SSB). SSB is a 2696 hardware security vulnerability and its exploitation takes advantage 2697 of speculative execution in a similar way to the Meltdown and Spectre 2698 security vulnerabilities. 2699 2700config MITIGATION_ITS 2701 bool "Enable Indirect Target Selection mitigation" 2702 depends on CPU_SUP_INTEL && X86_64 2703 depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK 2704 select EXECMEM 2705 default y 2706 help 2707 Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in 2708 BPU on some Intel CPUs that may allow Spectre V2 style attacks. If 2709 disabled, mitigation cannot be enabled via cmdline. 2710 See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst> 2711 2712config MITIGATION_TSA 2713 bool "Mitigate Transient Scheduler Attacks" 2714 depends on CPU_SUP_AMD 2715 default y 2716 help 2717 Enable mitigation for Transient Scheduler Attacks. TSA is a hardware 2718 security vulnerability on AMD CPUs which can lead to forwarding of 2719 invalid info to subsequent instructions and thus can affect their 2720 timing and thereby cause a leakage. 2721 2722config MITIGATION_VMSCAPE 2723 bool "Mitigate VMSCAPE" 2724 depends on KVM 2725 default y 2726 help 2727 Enable mitigation for VMSCAPE attacks. VMSCAPE is a hardware security 2728 vulnerability on Intel and AMD CPUs that may allow a guest to do 2729 Spectre v2 style attacks on userspace hypervisor. 2730endif 2731 2732config ARCH_HAS_ADD_PAGES 2733 def_bool y 2734 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2735 2736menu "Power management and ACPI options" 2737 2738config ARCH_HIBERNATION_HEADER 2739 def_bool y 2740 depends on HIBERNATION 2741 2742source "kernel/power/Kconfig" 2743 2744source "drivers/acpi/Kconfig" 2745 2746config X86_APM_BOOT 2747 def_bool y 2748 depends on APM 2749 2750menuconfig APM 2751 tristate "APM (Advanced Power Management) BIOS support" 2752 depends on X86_32 && PM_SLEEP 2753 help 2754 APM is a BIOS specification for saving power using several different 2755 techniques. This is mostly useful for battery powered laptops with 2756 APM compliant BIOSes. If you say Y here, the system time will be 2757 reset after a RESUME operation, the /proc/apm device will provide 2758 battery status information, and user-space programs will receive 2759 notification of APM "events" (e.g. battery status change). 2760 2761 If you select "Y" here, you can disable actual use of the APM 2762 BIOS by passing the "apm=off" option to the kernel at boot time. 2763 2764 Note that the APM support is almost completely disabled for 2765 machines with more than one CPU. 2766 2767 In order to use APM, you will need supporting software. For location 2768 and more information, read <file:Documentation/power/apm-acpi.rst> 2769 and the Battery Powered Linux mini-HOWTO, available from 2770 <http://www.tldp.org/docs.html#howto>. 2771 2772 This driver does not spin down disk drives (see the hdparm(8) 2773 manpage ("man 8 hdparm") for that), and it doesn't turn off 2774 VESA-compliant "green" monitors. 2775 2776 This driver does not support the TI 4000M TravelMate and the ACER 2777 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2778 desktop machines also don't have compliant BIOSes, and this driver 2779 may cause those machines to panic during the boot phase. 2780 2781 Generally, if you don't have a battery in your machine, there isn't 2782 much point in using this driver and you should say N. If you get 2783 random kernel OOPSes or reboots that don't seem to be related to 2784 anything, try disabling/enabling this option (or disabling/enabling 2785 APM in your BIOS). 2786 2787 Some other things you should try when experiencing seemingly random, 2788 "weird" problems: 2789 2790 1) make sure that you have enough swap space and that it is 2791 enabled. 2792 2) pass the "idle=poll" option to the kernel 2793 3) switch on floating point emulation in the kernel and pass 2794 the "no387" option to the kernel 2795 4) pass the "floppy=nodma" option to the kernel 2796 5) pass the "mem=4M" option to the kernel (thereby disabling 2797 all but the first 4 MB of RAM) 2798 6) make sure that the CPU is not over clocked. 2799 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2800 8) disable the cache from your BIOS settings 2801 9) install a fan for the video card or exchange video RAM 2802 10) install a better fan for the CPU 2803 11) exchange RAM chips 2804 12) exchange the motherboard. 2805 2806 To compile this driver as a module, choose M here: the 2807 module will be called apm. 2808 2809if APM 2810 2811config APM_IGNORE_USER_SUSPEND 2812 bool "Ignore USER SUSPEND" 2813 help 2814 This option will ignore USER SUSPEND requests. On machines with a 2815 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2816 series notebooks, it is necessary to say Y because of a BIOS bug. 2817 2818config APM_DO_ENABLE 2819 bool "Enable PM at boot time" 2820 help 2821 Enable APM features at boot time. From page 36 of the APM BIOS 2822 specification: "When disabled, the APM BIOS does not automatically 2823 power manage devices, enter the Standby State, enter the Suspend 2824 State, or take power saving steps in response to CPU Idle calls." 2825 This driver will make CPU Idle calls when Linux is idle (unless this 2826 feature is turned off -- see "Do CPU IDLE calls", below). This 2827 should always save battery power, but more complicated APM features 2828 will be dependent on your BIOS implementation. You may need to turn 2829 this option off if your computer hangs at boot time when using APM 2830 support, or if it beeps continuously instead of suspending. Turn 2831 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2832 T400CDT. This is off by default since most machines do fine without 2833 this feature. 2834 2835config APM_CPU_IDLE 2836 depends on CPU_IDLE 2837 bool "Make CPU Idle calls when idle" 2838 help 2839 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2840 On some machines, this can activate improved power savings, such as 2841 a slowed CPU clock rate, when the machine is idle. These idle calls 2842 are made after the idle loop has run for some length of time (e.g., 2843 333 mS). On some machines, this will cause a hang at boot time or 2844 whenever the CPU becomes idle. (On machines with more than one CPU, 2845 this option does nothing.) 2846 2847config APM_DISPLAY_BLANK 2848 bool "Enable console blanking using APM" 2849 help 2850 Enable console blanking using the APM. Some laptops can use this to 2851 turn off the LCD backlight when the screen blanker of the Linux 2852 virtual console blanks the screen. Note that this is only used by 2853 the virtual console screen blanker, and won't turn off the backlight 2854 when using the X Window system. This also doesn't have anything to 2855 do with your VESA-compliant power-saving monitor. Further, this 2856 option doesn't work for all laptops -- it might not turn off your 2857 backlight at all, or it might print a lot of errors to the console, 2858 especially if you are using gpm. 2859 2860config APM_ALLOW_INTS 2861 bool "Allow interrupts during APM BIOS calls" 2862 help 2863 Normally we disable external interrupts while we are making calls to 2864 the APM BIOS as a measure to lessen the effects of a badly behaving 2865 BIOS implementation. The BIOS should reenable interrupts if it 2866 needs to. Unfortunately, some BIOSes do not -- especially those in 2867 many of the newer IBM Thinkpads. If you experience hangs when you 2868 suspend, try setting this to Y. Otherwise, say N. 2869 2870endif # APM 2871 2872source "drivers/cpufreq/Kconfig" 2873 2874source "drivers/cpuidle/Kconfig" 2875 2876source "drivers/idle/Kconfig" 2877 2878endmenu 2879 2880menu "Bus options (PCI etc.)" 2881 2882choice 2883 prompt "PCI access mode" 2884 depends on X86_32 && PCI 2885 default PCI_GOANY 2886 help 2887 On PCI systems, the BIOS can be used to detect the PCI devices and 2888 determine their configuration. However, some old PCI motherboards 2889 have BIOS bugs and may crash if this is done. Also, some embedded 2890 PCI-based systems don't have any BIOS at all. Linux can also try to 2891 detect the PCI hardware directly without using the BIOS. 2892 2893 With this option, you can specify how Linux should detect the 2894 PCI devices. If you choose "BIOS", the BIOS will be used, 2895 if you choose "Direct", the BIOS won't be used, and if you 2896 choose "MMConfig", then PCI Express MMCONFIG will be used. 2897 If you choose "Any", the kernel will try MMCONFIG, then the 2898 direct access method and falls back to the BIOS if that doesn't 2899 work. If unsure, go with the default, which is "Any". 2900 2901config PCI_GOBIOS 2902 bool "BIOS" 2903 2904config PCI_GOMMCONFIG 2905 bool "MMConfig" 2906 2907config PCI_GODIRECT 2908 bool "Direct" 2909 2910config PCI_GOOLPC 2911 bool "OLPC XO-1" 2912 depends on OLPC 2913 2914config PCI_GOANY 2915 bool "Any" 2916 2917endchoice 2918 2919config PCI_BIOS 2920 def_bool y 2921 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2922 2923# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2924config PCI_DIRECT 2925 def_bool y 2926 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2927 2928config PCI_MMCONFIG 2929 bool "Support mmconfig PCI config space access" if X86_64 2930 default y 2931 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2932 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2933 help 2934 Add support for accessing the PCI configuration space as a memory 2935 mapped area. It is the recommended method if the system supports 2936 this (it must have PCI Express and ACPI for it to be available). 2937 2938 In the unlikely case that enabling this configuration option causes 2939 problems, the mechanism can be switched off with the 'pci=nommconf' 2940 command line parameter. 2941 2942 Say N only if you are sure that your platform does not support this 2943 access method or you have problems caused by it. 2944 2945 Say Y otherwise. 2946 2947config PCI_OLPC 2948 def_bool y 2949 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2950 2951config PCI_XEN 2952 def_bool y 2953 depends on PCI && XEN 2954 2955config MMCONF_FAM10H 2956 def_bool y 2957 depends on X86_64 && PCI_MMCONFIG && ACPI 2958 2959config PCI_CNB20LE_QUIRK 2960 bool "Read PCI host bridge windows from the CNB20LE chipset" if EXPERT 2961 depends on X86_32 && PCI 2962 help 2963 Read the PCI windows out of the CNB20LE host bridge. This allows 2964 PCI hotplug to work on systems with the CNB20LE chipset which do 2965 not have ACPI. 2966 2967 The ServerWorks (later Broadcom) CNB20LE was a chipset designed 2968 most probably only for Pentium III. 2969 2970 To find out if you have such a chipset, search for a PCI device with 2971 1166:0009 PCI IDs, for example by executing 2972 lspci -nn | grep '1166:0009' 2973 The code is inactive if there is none. 2974 2975 There's no public spec for this chipset, and this functionality 2976 is known to be incomplete. 2977 2978 You should say N unless you know you need this. 2979 2980config ISA_BUS 2981 bool "ISA bus support on modern systems" if EXPERT 2982 help 2983 Expose ISA bus device drivers and options available for selection and 2984 configuration. Enable this option if your target machine has an ISA 2985 bus. ISA is an older system, displaced by PCI and newer bus 2986 architectures -- if your target machine is modern, it probably does 2987 not have an ISA bus. 2988 2989 If unsure, say N. 2990 2991# x86_64 have no ISA slots, but can have ISA-style DMA. 2992config ISA_DMA_API 2993 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2994 default y 2995 help 2996 Enables ISA-style DMA support for devices requiring such controllers. 2997 If unsure, say Y. 2998 2999if X86_32 3000 3001config ISA 3002 bool "ISA support" 3003 help 3004 Find out whether you have ISA slots on your motherboard. ISA is the 3005 name of a bus system, i.e. the way the CPU talks to the other stuff 3006 inside your box. Other bus systems are PCI, EISA, MicroChannel 3007 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 3008 newer boards don't support it. If you have ISA, say Y, otherwise N. 3009 3010config SCx200 3011 tristate "NatSemi SCx200 support" 3012 help 3013 This provides basic support for National Semiconductor's 3014 (now AMD's) Geode processors. The driver probes for the 3015 PCI-IDs of several on-chip devices, so its a good dependency 3016 for other scx200_* drivers. 3017 3018 If compiled as a module, the driver is named scx200. 3019 3020config SCx200HR_TIMER 3021 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 3022 depends on SCx200 3023 default y 3024 help 3025 This driver provides a clocksource built upon the on-chip 3026 27MHz high-resolution timer. Its also a workaround for 3027 NSC Geode SC-1100's buggy TSC, which loses time when the 3028 processor goes idle (as is done by the scheduler). The 3029 other workaround is idle=poll boot option. 3030 3031config OLPC 3032 bool "One Laptop Per Child support" 3033 depends on !X86_PAE 3034 select GPIOLIB 3035 select OF 3036 select OF_PROMTREE 3037 select IRQ_DOMAIN 3038 select OLPC_EC 3039 help 3040 Add support for detecting the unique features of the OLPC 3041 XO hardware. 3042 3043config OLPC_XO1_PM 3044 bool "OLPC XO-1 Power Management" 3045 depends on OLPC && MFD_CS5535=y && PM_SLEEP 3046 help 3047 Add support for poweroff and suspend of the OLPC XO-1 laptop. 3048 3049config OLPC_XO1_RTC 3050 bool "OLPC XO-1 Real Time Clock" 3051 depends on OLPC_XO1_PM && RTC_DRV_CMOS 3052 help 3053 Add support for the XO-1 real time clock, which can be used as a 3054 programmable wakeup source. 3055 3056config OLPC_XO1_SCI 3057 bool "OLPC XO-1 SCI extras" 3058 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 3059 depends on INPUT=y 3060 select POWER_SUPPLY 3061 help 3062 Add support for SCI-based features of the OLPC XO-1 laptop: 3063 - EC-driven system wakeups 3064 - Power button 3065 - Ebook switch 3066 - Lid switch 3067 - AC adapter status updates 3068 - Battery status updates 3069 3070config OLPC_XO15_SCI 3071 bool "OLPC XO-1.5 SCI extras" 3072 depends on OLPC && ACPI 3073 select POWER_SUPPLY 3074 help 3075 Add support for SCI-based features of the OLPC XO-1.5 laptop: 3076 - EC-driven system wakeups 3077 - AC adapter status updates 3078 - Battery status updates 3079 3080config GEODE_COMMON 3081 bool 3082 3083config ALIX 3084 bool "PCEngines ALIX System Support (LED setup)" 3085 select GPIOLIB 3086 select GEODE_COMMON 3087 help 3088 This option enables system support for the PCEngines ALIX. 3089 At present this just sets up LEDs for GPIO control on 3090 ALIX2/3/6 boards. However, other system specific setup should 3091 get added here. 3092 3093 Note: You must still enable the drivers for GPIO and LED support 3094 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 3095 3096 Note: You have to set alix.force=1 for boards with Award BIOS. 3097 3098config NET5501 3099 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3100 select GPIOLIB 3101 select GEODE_COMMON 3102 help 3103 This option enables system support for the Soekris Engineering net5501. 3104 3105config GEOS 3106 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3107 select GPIOLIB 3108 select GEODE_COMMON 3109 depends on DMI 3110 help 3111 This option enables system support for the Traverse Technologies GEOS. 3112 3113config TS5500 3114 bool "Technologic Systems TS-5500 platform support" 3115 depends on MELAN 3116 select CHECK_SIGNATURE 3117 select NEW_LEDS 3118 select LEDS_CLASS 3119 help 3120 This option enables system support for the Technologic Systems TS-5500. 3121 3122endif # X86_32 3123 3124config AMD_NB 3125 def_bool y 3126 depends on AMD_NODE 3127 3128config AMD_NODE 3129 def_bool y 3130 depends on CPU_SUP_AMD && PCI 3131 3132endmenu 3133 3134menu "Binary Emulations" 3135 3136config IA32_EMULATION 3137 bool "IA32 Emulation" 3138 depends on X86_64 3139 select ARCH_WANT_OLD_COMPAT_IPC 3140 select BINFMT_ELF 3141 select COMPAT_OLD_SIGACTION 3142 help 3143 Include code to run legacy 32-bit programs under a 3144 64-bit kernel. You should likely turn this on, unless you're 3145 100% sure that you don't have any 32-bit programs left. 3146 3147config IA32_EMULATION_DEFAULT_DISABLED 3148 bool "IA32 emulation disabled by default" 3149 default n 3150 depends on IA32_EMULATION 3151 help 3152 Make IA32 emulation disabled by default. This prevents loading 32-bit 3153 processes and access to 32-bit syscalls. If unsure, leave it to its 3154 default value. 3155 3156config X86_X32_ABI 3157 bool "x32 ABI for 64-bit mode" 3158 depends on X86_64 3159 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3160 # compressed debug sections to x86_x32 properly: 3161 # https://github.com/ClangBuiltLinux/linux/issues/514 3162 # https://github.com/ClangBuiltLinux/linux/issues/1141 3163 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3164 help 3165 Include code to run binaries for the x32 native 32-bit ABI 3166 for 64-bit processors. An x32 process gets access to the 3167 full 64-bit register file and wide data path while leaving 3168 pointers at 32 bits for smaller memory footprint. 3169 3170config COMPAT_32 3171 def_bool y 3172 depends on IA32_EMULATION || X86_32 3173 select HAVE_UID16 3174 select OLD_SIGSUSPEND3 3175 3176config COMPAT 3177 def_bool y 3178 depends on IA32_EMULATION || X86_X32_ABI 3179 3180config COMPAT_FOR_U64_ALIGNMENT 3181 def_bool y 3182 depends on COMPAT 3183 3184endmenu 3185 3186config HAVE_ATOMIC_IOMAP 3187 def_bool y 3188 depends on X86_32 3189 3190source "arch/x86/kvm/Kconfig" 3191 3192source "arch/x86/Kconfig.cpufeatures" 3193 3194source "arch/x86/Kconfig.assembler" 3195