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_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 73 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 74 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 75 select ARCH_HAS_CPU_ATTACK_VECTORS if CPU_MITIGATIONS 76 select ARCH_HAS_CACHE_LINE_SIZE 77 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 78 select ARCH_HAS_CPU_FINALIZE_INIT 79 select ARCH_HAS_CPU_PASID if IOMMU_SVA 80 select ARCH_HAS_CURRENT_STACK_POINTER 81 select ARCH_HAS_DEBUG_VIRTUAL 82 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 83 select ARCH_HAS_DEVMEM_IS_ALLOWED 84 select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN 85 select ARCH_HAS_EARLY_DEBUG if KGDB 86 select ARCH_HAS_ELF_RANDOMIZE 87 select ARCH_HAS_EXECMEM_ROX if X86_64 && STRICT_MODULE_RWX 88 select ARCH_HAS_FAST_MULTIPLIER 89 select ARCH_HAS_FORTIFY_SOURCE 90 select ARCH_HAS_GCOV_PROFILE_ALL 91 select ARCH_HAS_KCOV if X86_64 92 select ARCH_HAS_KERNEL_FPU_SUPPORT 93 select ARCH_HAS_MEM_ENCRYPT 94 select ARCH_HAS_MEMBARRIER_SYNC_CORE 95 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 96 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 97 select ARCH_HAS_PMEM_API if X86_64 98 select ARCH_HAS_PREEMPT_LAZY 99 select ARCH_HAS_PTDUMP 100 select ARCH_HAS_PTE_SPECIAL 101 select ARCH_HAS_HW_PTE_YOUNG 102 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 103 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 104 select ARCH_HAS_COPY_MC if X86_64 105 select ARCH_HAS_SET_MEMORY 106 select ARCH_HAS_SET_DIRECT_MAP 107 select ARCH_HAS_STRICT_KERNEL_RWX 108 select ARCH_HAS_STRICT_MODULE_RWX 109 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 110 select ARCH_HAS_SYSCALL_WRAPPER 111 select ARCH_HAS_UBSAN 112 select ARCH_HAS_DEBUG_WX 113 select ARCH_HAS_ZONE_DMA_SET if EXPERT 114 select ARCH_HAVE_NMI_SAFE_CMPXCHG 115 select ARCH_HAVE_EXTRA_ELF_NOTES 116 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 117 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 118 select ARCH_MIGHT_HAVE_PC_PARPORT 119 select ARCH_MIGHT_HAVE_PC_SERIO 120 select ARCH_STACKWALK 121 select ARCH_SUPPORTS_ACPI 122 select ARCH_SUPPORTS_ATOMIC_RMW 123 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 124 select ARCH_SUPPORTS_HUGETLBFS 125 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 126 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 127 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 128 select ARCH_SUPPORTS_CFI if X86_64 129 select ARCH_USES_CFI_TRAPS if X86_64 && CFI 130 select ARCH_SUPPORTS_LTO_CLANG 131 select ARCH_SUPPORTS_LTO_CLANG_THIN 132 select ARCH_SUPPORTS_RT 133 select ARCH_SUPPORTS_AUTOFDO_CLANG 134 select ARCH_SUPPORTS_PROPELLER_CLANG if X86_64 135 select ARCH_USE_BUILTIN_BSWAP 136 select ARCH_USE_CMPXCHG_LOCKREF if X86_CX8 137 select ARCH_USE_MEMTEST 138 select ARCH_USE_QUEUED_RWLOCKS 139 select ARCH_USE_QUEUED_SPINLOCKS 140 select ARCH_USE_SYM_ANNOTATIONS 141 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 142 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 143 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 144 select ARCH_WANTS_NO_INSTR 145 select ARCH_WANT_GENERAL_HUGETLB 146 select ARCH_WANT_HUGE_PMD_SHARE if X86_64 147 select ARCH_WANT_LD_ORPHAN_WARN 148 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 149 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 150 select ARCH_WANT_HUGETLB_VMEMMAP_PREINIT if X86_64 151 select ARCH_WANTS_THP_SWAP if X86_64 152 select ARCH_HAS_PARANOID_L1D_FLUSH 153 select ARCH_WANT_IRQS_OFF_ACTIVATE_MM 154 select BUILDTIME_TABLE_SORT 155 select CLKEVT_I8253 156 select CLOCKSOURCE_WATCHDOG 157 # Word-size accesses may read uninitialized data past the trailing \0 158 # in strings and cause false KMSAN reports. 159 select DCACHE_WORD_ACCESS if !KMSAN 160 select DYNAMIC_SIGFRAME 161 select EDAC_ATOMIC_SCRUB 162 select EDAC_SUPPORT 163 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 164 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 165 select GENERIC_CLOCKEVENTS_MIN_ADJUST 166 select GENERIC_CMOS_UPDATE 167 select GENERIC_CPU_AUTOPROBE 168 select GENERIC_CPU_DEVICES 169 select GENERIC_CPU_VULNERABILITIES 170 select GENERIC_EARLY_IOREMAP 171 select GENERIC_ENTRY 172 select GENERIC_IOMAP 173 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 174 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 175 select GENERIC_IRQ_MIGRATION if SMP 176 select GENERIC_IRQ_PROBE 177 select GENERIC_IRQ_RESERVATION_MODE 178 select GENERIC_IRQ_SHOW 179 select GENERIC_PENDING_IRQ if SMP 180 select GENERIC_SMP_IDLE_THREAD 181 select GENERIC_TIME_VSYSCALL 182 select GENERIC_GETTIMEOFDAY 183 select GENERIC_VDSO_OVERFLOW_PROTECT 184 select GUP_GET_PXX_LOW_HIGH if X86_PAE 185 select HARDIRQS_SW_RESEND 186 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 187 select HAS_IOPORT 188 select HAVE_ACPI_APEI if ACPI 189 select HAVE_ACPI_APEI_NMI if ACPI 190 select HAVE_ALIGNED_STRUCT_PAGE 191 select HAVE_ARCH_AUDITSYSCALL 192 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 193 select HAVE_ARCH_HUGE_VMALLOC if X86_64 194 select HAVE_ARCH_JUMP_LABEL 195 select HAVE_ARCH_JUMP_LABEL_RELATIVE 196 select HAVE_ARCH_KASAN if X86_64 197 select HAVE_ARCH_KASAN_VMALLOC if X86_64 198 select HAVE_ARCH_KFENCE 199 select HAVE_ARCH_KMSAN if X86_64 200 select HAVE_ARCH_KGDB 201 select HAVE_ARCH_KSTACK_ERASE 202 select HAVE_ARCH_MMAP_RND_BITS if MMU 203 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 204 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 205 select HAVE_ARCH_PREL32_RELOCATIONS 206 select HAVE_ARCH_SECCOMP_FILTER 207 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 208 select HAVE_ARCH_TRACEHOOK 209 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 210 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 211 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 212 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 213 select HAVE_ARCH_VMAP_STACK if X86_64 214 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 215 select HAVE_ARCH_WITHIN_STACK_FRAMES 216 select HAVE_ASM_MODVERSIONS 217 select HAVE_CMPXCHG_DOUBLE 218 select HAVE_CMPXCHG_LOCAL 219 select HAVE_CONTEXT_TRACKING_USER if X86_64 220 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 221 select HAVE_C_RECORDMCOUNT 222 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 223 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 224 select HAVE_BUILDTIME_MCOUNT_SORT 225 select HAVE_DEBUG_KMEMLEAK 226 select HAVE_DMA_CONTIGUOUS 227 select HAVE_DYNAMIC_FTRACE 228 select HAVE_DYNAMIC_FTRACE_WITH_REGS 229 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 230 select HAVE_FTRACE_REGS_HAVING_PT_REGS if X86_64 231 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 232 select HAVE_DYNAMIC_FTRACE_WITH_JMP if X86_64 233 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 234 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 235 select HAVE_EBPF_JIT 236 select HAVE_EFFICIENT_UNALIGNED_ACCESS 237 select HAVE_EISA if X86_32 238 select HAVE_EXIT_THREAD 239 select HAVE_GENERIC_TIF_BITS 240 select HAVE_GUP_FAST 241 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 242 select HAVE_FTRACE_GRAPH_FUNC if HAVE_FUNCTION_GRAPH_TRACER 243 select HAVE_FUNCTION_GRAPH_FREGS if HAVE_FUNCTION_GRAPH_TRACER 244 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 245 select HAVE_FUNCTION_TRACER 246 select HAVE_GCC_PLUGINS 247 select HAVE_HW_BREAKPOINT 248 select HAVE_IOREMAP_PROT 249 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 250 select HAVE_IRQ_TIME_ACCOUNTING 251 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 252 select HAVE_KERNEL_BZIP2 253 select HAVE_KERNEL_GZIP 254 select HAVE_KERNEL_LZ4 255 select HAVE_KERNEL_LZMA 256 select HAVE_KERNEL_LZO 257 select HAVE_KERNEL_XZ 258 select HAVE_KERNEL_ZSTD 259 select HAVE_KPROBES 260 select HAVE_KPROBES_ON_FTRACE 261 select HAVE_FUNCTION_ERROR_INJECTION 262 select HAVE_KRETPROBES 263 select HAVE_RETHOOK 264 select HAVE_KLP_BUILD if X86_64 265 select HAVE_LIVEPATCH if X86_64 266 select HAVE_MIXED_BREAKPOINTS_REGS 267 select HAVE_MOD_ARCH_SPECIFIC 268 select HAVE_MOVE_PMD 269 select HAVE_MOVE_PUD 270 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 271 select HAVE_NMI 272 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 273 select HAVE_OBJTOOL if X86_64 274 select HAVE_OPTPROBES 275 select HAVE_PAGE_SIZE_4KB 276 select HAVE_PCSPKR_PLATFORM 277 select HAVE_PERF_EVENTS 278 select HAVE_PERF_EVENTS_NMI 279 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 280 select HAVE_PCI 281 select HAVE_PERF_REGS 282 select HAVE_PERF_USER_STACK_DUMP 283 select ASYNC_KERNEL_PGTABLE_FREE if IOMMU_SVA 284 select MMU_GATHER_RCU_TABLE_FREE 285 select MMU_GATHER_MERGE_VMAS 286 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 287 select HAVE_REGS_AND_STACK_ACCESS_API 288 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 289 select HAVE_FUNCTION_ARG_ACCESS_API 290 select HAVE_SETUP_PER_CPU_AREA 291 select HAVE_SOFTIRQ_ON_OWN_STACK 292 select HAVE_STACKPROTECTOR 293 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 294 select HAVE_STATIC_CALL 295 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 296 select HAVE_PREEMPT_DYNAMIC_CALL 297 select HAVE_RSEQ 298 select HAVE_RUST if X86_64 299 select HAVE_SYSCALL_TRACEPOINTS 300 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 301 select HAVE_UNSTABLE_SCHED_CLOCK 302 select HAVE_UNWIND_USER_FP if X86_64 303 select HAVE_USER_RETURN_NOTIFIER 304 select HAVE_GENERIC_VDSO 305 select VDSO_GETRANDOM if X86_64 306 select HOTPLUG_PARALLEL if SMP && X86_64 307 select HOTPLUG_SMT if SMP 308 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 309 select IRQ_FORCED_THREADING 310 select LOCK_MM_AND_FIND_VMA 311 select NEED_PER_CPU_EMBED_FIRST_CHUNK 312 select NEED_PER_CPU_PAGE_FIRST_CHUNK 313 select NEED_SG_DMA_LENGTH 314 select NUMA_MEMBLKS if NUMA 315 select PCI_DOMAINS if PCI 316 select PCI_LOCKLESS_CONFIG if PCI 317 select PERF_EVENTS 318 select RTC_LIB 319 select RTC_MC146818_LIB 320 select SPARSE_IRQ 321 select SYSCTL_EXCEPTION_TRACE 322 select THREAD_INFO_IN_TASK 323 select TRACE_IRQFLAGS_SUPPORT 324 select TRACE_IRQFLAGS_NMI_SUPPORT 325 select USER_STACKTRACE_SUPPORT 326 select HAVE_ARCH_KCSAN if X86_64 327 select PROC_PID_ARCH_STATUS if PROC_FS 328 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 329 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 330 select FUNCTION_ALIGNMENT_4B 331 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 332 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 333 select ARCH_SUPPORTS_SCHED_SMT if SMP 334 select SCHED_SMT if SMP 335 select ARCH_SUPPORTS_SCHED_CLUSTER if SMP 336 select ARCH_SUPPORTS_SCHED_MC if SMP 337 select HAVE_SINGLE_FTRACE_DIRECT_OPS if X86_64 && DYNAMIC_FTRACE_WITH_DIRECT_CALLS 338 339config INSTRUCTION_DECODER 340 def_bool y 341 depends on KPROBES || PERF_EVENTS || UPROBES 342 343config OUTPUT_FORMAT 344 string 345 default "elf32-i386" if X86_32 346 default "elf64-x86-64" if X86_64 347 348config LOCKDEP_SUPPORT 349 def_bool y 350 351config STACKTRACE_SUPPORT 352 def_bool y 353 354config MMU 355 def_bool y 356 357config ARCH_MMAP_RND_BITS_MIN 358 default 28 if 64BIT 359 default 8 360 361config ARCH_MMAP_RND_BITS_MAX 362 default 32 if 64BIT 363 default 16 364 365config ARCH_MMAP_RND_COMPAT_BITS_MIN 366 default 8 367 368config ARCH_MMAP_RND_COMPAT_BITS_MAX 369 default 16 370 371config SBUS 372 bool 373 374config GENERIC_ISA_DMA 375 def_bool y 376 depends on ISA_DMA_API 377 378config GENERIC_CSUM 379 bool 380 default y if KMSAN || KASAN 381 382config GENERIC_BUG 383 def_bool y 384 depends on BUG 385 select GENERIC_BUG_RELATIVE_POINTERS 386 387config GENERIC_BUG_RELATIVE_POINTERS 388 bool 389 390config ARCH_MAY_HAVE_PC_FDC 391 def_bool y 392 depends on ISA_DMA_API 393 394config GENERIC_CALIBRATE_DELAY 395 def_bool y 396 397config ARCH_HAS_CPU_RELAX 398 def_bool y 399 400config ARCH_HIBERNATION_POSSIBLE 401 def_bool y 402 403config ARCH_SUSPEND_POSSIBLE 404 def_bool y 405 406config AUDIT_ARCH 407 def_bool y if X86_64 408 409config KASAN_SHADOW_OFFSET 410 hex 411 depends on KASAN 412 default 0xdffffc0000000000 413 414config HAVE_INTEL_TXT 415 def_bool y 416 depends on INTEL_IOMMU && ACPI 417 418config ARCH_SUPPORTS_UPROBES 419 def_bool y 420 421config FIX_EARLYCON_MEM 422 def_bool y 423 424config DYNAMIC_PHYSICAL_MASK 425 bool 426 427config PGTABLE_LEVELS 428 int 429 default 5 if X86_64 430 default 3 if X86_PAE 431 default 2 432 433menu "Processor type and features" 434 435config SMP 436 bool "Symmetric multi-processing support" 437 help 438 This enables support for systems with more than one CPU. If you have 439 a system with only one CPU, say N. If you have a system with more 440 than one CPU, say Y. 441 442 If you say N here, the kernel will run on uni- and multiprocessor 443 machines, but will use only one CPU of a multiprocessor machine. If 444 you say Y here, the kernel will run on many, but not all, 445 uniprocessor machines. On a uniprocessor machine, the kernel 446 will run faster if you say N here. 447 448 Note that if you say Y here and choose architecture "586" or 449 "Pentium" under "Processor family", the kernel will not work on 486 450 architectures. Similarly, multiprocessor kernels for the "PPro" 451 architecture may not work on all Pentium based boards. 452 453 People using multiprocessor machines who say Y here should also say 454 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 455 Management" code will be disabled if you say Y here. 456 457 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 458 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 459 <http://www.tldp.org/docs.html#howto>. 460 461 If you don't know what to do here, say N. 462 463config X86_X2APIC 464 bool "x2APIC interrupt controller architecture support" 465 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 466 default y 467 help 468 x2APIC is an interrupt controller architecture, a component of which 469 (the local APIC) is present in the CPU. It allows faster access to 470 the local APIC and supports a larger number of CPUs in the system 471 than the predecessors. 472 473 x2APIC was introduced in Intel CPUs around 2008 and in AMD EPYC CPUs 474 in 2019, but it can be disabled by the BIOS. It is also frequently 475 emulated in virtual machines, even when the host CPU does not support 476 it. Support in the CPU can be checked by executing 477 grep x2apic /proc/cpuinfo 478 479 If this configuration option is disabled, the kernel will boot with 480 very reduced functionality and performance on some platforms that 481 have x2APIC enabled. On the other hand, on hardware that does not 482 support x2APIC, a kernel with this option enabled will just fallback 483 to older APIC implementations. 484 485 If in doubt, say Y. 486 487config AMD_SECURE_AVIC 488 bool "AMD Secure AVIC" 489 depends on AMD_MEM_ENCRYPT && X86_X2APIC 490 help 491 Enable this to get AMD Secure AVIC support on guests that have this feature. 492 493 AMD Secure AVIC provides hardware acceleration for performance sensitive 494 APIC accesses and support for managing guest owned APIC state for SEV-SNP 495 guests. Secure AVIC does not support xAPIC mode. It has functional 496 dependency on x2apic being enabled in the guest. 497 498 If you don't know what to do here, say N. 499 500config X86_POSTED_MSI 501 bool "Enable MSI and MSI-x delivery by posted interrupts" 502 depends on X86_64 && IRQ_REMAP 503 help 504 This enables MSIs that are under interrupt remapping to be delivered as 505 posted interrupts to the host kernel. Interrupt throughput can 506 potentially be improved by coalescing CPU notifications during high 507 frequency bursts. 508 509 If you don't know what to do here, say N. 510 511config X86_MPPARSE 512 bool "Enable MPS table" if ACPI 513 default y 514 depends on X86_LOCAL_APIC 515 help 516 For old smp systems that do not have proper acpi support. Newer systems 517 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 518 519config X86_CPU_RESCTRL 520 bool "x86 CPU resource control support" 521 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 522 depends on MISC_FILESYSTEMS 523 select ARCH_HAS_CPU_RESCTRL 524 select RESCTRL_FS 525 select RESCTRL_FS_PSEUDO_LOCK 526 help 527 Enable x86 CPU resource control support. 528 529 Provide support for the allocation and monitoring of system resources 530 usage by the CPU. 531 532 Intel calls this Intel Resource Director Technology 533 (Intel(R) RDT). More information about RDT can be found in the 534 Intel x86 Architecture Software Developer Manual. 535 536 AMD calls this AMD Platform Quality of Service (AMD QoS). 537 More information about AMD QoS can be found in the AMD64 Technology 538 Platform Quality of Service Extensions manual. 539 540 Say N if unsure. 541 542config X86_CPU_RESCTRL_INTEL_AET 543 bool "Intel Application Energy Telemetry" 544 depends on X86_64 && X86_CPU_RESCTRL && CPU_SUP_INTEL && INTEL_PMT_TELEMETRY=y && INTEL_TPMI=y 545 help 546 Enable per-RMID telemetry events in resctrl. 547 548 Intel feature that collects per-RMID execution data 549 about energy consumption, measure of frequency independent 550 activity and other performance metrics. Data is aggregated 551 per package. 552 553 Say N if unsure. 554 555config X86_FRED 556 bool "Flexible Return and Event Delivery" 557 depends on X86_64 558 help 559 When enabled, try to use Flexible Return and Event Delivery 560 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 561 ring transitions and exception/interrupt handling if the 562 system supports it. 563 564config X86_EXTENDED_PLATFORM 565 bool "Support for extended (non-PC) x86 platforms" 566 default y 567 help 568 If you disable this option then the kernel will only support 569 standard PC platforms. (which covers the vast majority of 570 systems out there.) 571 572 If you enable this option then you'll be able to select support 573 for the following non-PC x86 platforms, depending on the value of 574 CONFIG_64BIT. 575 576 32-bit platforms (CONFIG_64BIT=n): 577 Goldfish (mostly Android emulator) 578 Intel CE media processor (CE4100) SoC 579 Intel Quark 580 RDC R-321x SoC 581 582 64-bit platforms (CONFIG_64BIT=y): 583 Numascale NumaChip 584 ScaleMP vSMP 585 SGI Ultraviolet 586 Merrifield/Moorefield MID devices 587 Goldfish (mostly Android emulator) 588 589 If you have one of these systems, or if you want to build a 590 generic distribution kernel, say Y here - otherwise say N. 591 592# This is an alphabetically sorted list of 64 bit extended platforms 593# Please maintain the alphabetic order if and when there are additions 594config X86_NUMACHIP 595 bool "Numascale NumaChip" 596 depends on X86_64 597 depends on X86_EXTENDED_PLATFORM 598 depends on NUMA 599 depends on SMP 600 depends on X86_X2APIC 601 depends on PCI_MMCONFIG 602 help 603 Adds support for Numascale NumaChip large-SMP systems. Needed to 604 enable more than ~168 cores. 605 If you don't have one of these, you should say N here. 606 607config X86_VSMP 608 bool "ScaleMP vSMP" 609 select HYPERVISOR_GUEST 610 select PARAVIRT 611 depends on X86_64 && PCI 612 depends on X86_EXTENDED_PLATFORM 613 depends on SMP 614 help 615 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 616 supposed to run on these EM64T-based machines. Only choose this option 617 if you have one of these machines. 618 619config X86_UV 620 bool "SGI Ultraviolet" 621 depends on X86_64 622 depends on X86_EXTENDED_PLATFORM 623 depends on NUMA 624 depends on EFI 625 depends on KEXEC_CORE 626 depends on X86_X2APIC 627 depends on PCI 628 help 629 This option is needed in order to support SGI Ultraviolet systems. 630 If you don't have one of these, you should say N here. 631 632config X86_INTEL_MID 633 bool "Intel Z34xx/Z35xx MID platform support" 634 depends on X86_EXTENDED_PLATFORM 635 depends on X86_PLATFORM_DEVICES 636 depends on PCI 637 depends on X86_64 || (EXPERT && PCI_GOANY) 638 depends on X86_IO_APIC 639 select I2C 640 select DW_APB_TIMER 641 select INTEL_SCU_PCI 642 help 643 Select to build a kernel capable of supporting 64-bit Intel MID 644 (Mobile Internet Device) platform systems which do not have 645 the PCI legacy interfaces. 646 647 The only supported devices are the 22nm Merrified (Z34xx) 648 and Moorefield (Z35xx) SoC used in the Intel Edison board and 649 a small number of Android devices such as the Asus Zenfone 2, 650 Asus FonePad 8 and Dell Venue 7. 651 652 If you are building for a PC class system or non-MID tablet 653 SoCs like Bay Trail (Z36xx/Z37xx), say N here. 654 655 Intel MID platforms are based on an Intel processor and chipset which 656 consume less power than most of the x86 derivatives. 657 658config X86_GOLDFISH 659 bool "Goldfish (Virtual Platform)" 660 depends on X86_EXTENDED_PLATFORM 661 help 662 Enable support for the Goldfish virtual platform used primarily 663 for Android development. Unless you are building for the Android 664 Goldfish emulator say N here. 665 666# Following is an alphabetically sorted list of 32 bit extended platforms 667# Please maintain the alphabetic order if and when there are additions 668 669config X86_INTEL_CE 670 bool "CE4100 TV platform" 671 depends on PCI 672 depends on PCI_GODIRECT 673 depends on X86_IO_APIC 674 depends on X86_32 675 depends on X86_EXTENDED_PLATFORM 676 select X86_REBOOTFIXUPS 677 select OF 678 select OF_EARLY_FLATTREE 679 help 680 Select for the Intel CE media processor (CE4100) SOC. 681 This option compiles in support for the CE4100 SOC for settop 682 boxes and media devices. 683 684config X86_INTEL_QUARK 685 bool "Intel Quark platform support" 686 depends on X86_32 687 depends on X86_EXTENDED_PLATFORM 688 depends on X86_PLATFORM_DEVICES 689 depends on X86_TSC 690 depends on PCI 691 depends on PCI_GOANY 692 depends on X86_IO_APIC 693 select IOSF_MBI 694 select INTEL_IMR 695 select COMMON_CLK 696 help 697 Select to include support for Quark X1000 SoC. 698 Say Y here if you have a Quark based system such as the Arduino 699 compatible Intel Galileo. 700 701config X86_RDC321X 702 bool "RDC R-321x SoC" 703 depends on X86_32 704 depends on X86_EXTENDED_PLATFORM 705 select M486 706 select X86_REBOOTFIXUPS 707 help 708 This option is needed for RDC R-321x system-on-chip, also known 709 as R-8610-(G). 710 If you don't have one of these chips, you should say N here. 711 712config X86_INTEL_LPSS 713 bool "Intel Low Power Subsystem Support" 714 depends on X86 && ACPI && PCI 715 select COMMON_CLK 716 select PINCTRL 717 select IOSF_MBI 718 help 719 Select to build support for Intel Low Power Subsystem such as 720 found on Intel Lynxpoint PCH. Selecting this option enables 721 things like clock tree (common clock framework) and pincontrol 722 which are needed by the LPSS peripheral drivers. 723 724config X86_AMD_PLATFORM_DEVICE 725 bool "AMD ACPI2Platform devices support" 726 depends on ACPI 727 select COMMON_CLK 728 select PINCTRL 729 help 730 Select to interpret AMD specific ACPI device to platform device 731 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 732 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 733 implemented under PINCTRL subsystem. 734 735config IOSF_MBI 736 tristate "Intel SoC IOSF Sideband support for SoC platforms" 737 depends on PCI 738 help 739 This option enables sideband register access support for Intel SoC 740 platforms. On these platforms the IOSF sideband is used in lieu of 741 MSR's for some register accesses, mostly but not limited to thermal 742 and power. Drivers may query the availability of this device to 743 determine if they need the sideband in order to work on these 744 platforms. The sideband is available on the following SoC products. 745 This list is not meant to be exclusive. 746 - BayTrail 747 - Braswell 748 - Quark 749 750 You should say Y if you are running a kernel on one of these SoC's. 751 752config IOSF_MBI_DEBUG 753 bool "Enable IOSF sideband access through debugfs" 754 depends on IOSF_MBI && DEBUG_FS 755 help 756 Select this option to expose the IOSF sideband access registers (MCR, 757 MDR, MCRX) through debugfs to write and read register information from 758 different units on the SoC. This is most useful for obtaining device 759 state information for debug and analysis. As this is a general access 760 mechanism, users of this option would have specific knowledge of the 761 device they want to access. 762 763 If you don't require the option or are in doubt, say N. 764 765config X86_SUPPORTS_MEMORY_FAILURE 766 def_bool y 767 # MCE code calls memory_failure(): 768 depends on X86_MCE 769 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 770 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 771 depends on X86_64 || !SPARSEMEM 772 select ARCH_SUPPORTS_MEMORY_FAILURE 773 774config X86_32_IRIS 775 tristate "Eurobraille/Iris poweroff module" 776 depends on X86_32 777 help 778 The Iris machines from EuroBraille do not have APM or ACPI support 779 to shut themselves down properly. A special I/O sequence is 780 needed to do so, which is what this module does at 781 kernel shutdown. 782 783 This is only for Iris machines from EuroBraille. 784 785 If unused, say N. 786 787config SCHED_OMIT_FRAME_POINTER 788 def_bool y 789 prompt "Single-depth WCHAN output" 790 depends on X86 791 help 792 Calculate simpler /proc/<PID>/wchan values. If this option 793 is disabled then wchan values will recurse back to the 794 caller function. This provides more accurate wchan values, 795 at the expense of slightly more scheduling overhead. 796 797 If in doubt, say "Y". 798 799menuconfig HYPERVISOR_GUEST 800 bool "Linux guest support" 801 help 802 Say Y here to enable options for running Linux under various hyper- 803 visors. This option enables basic hypervisor detection and platform 804 setup. 805 806 If you say N, all options in this submenu will be skipped and 807 disabled, and Linux guest support won't be built in. 808 809if HYPERVISOR_GUEST 810 811config PARAVIRT 812 bool "Enable paravirtualization code" 813 depends on HAVE_STATIC_CALL 814 select HAVE_PV_STEAL_CLOCK_GEN 815 help 816 This changes the kernel so it can modify itself when it is run 817 under a hypervisor, potentially improving performance significantly 818 over full virtualization. However, when run without a hypervisor 819 the kernel is theoretically slower and slightly larger. 820 821config PARAVIRT_XXL 822 bool 823 depends on X86_64 824 select ARCH_HAS_LAZY_MMU_MODE 825 826config PARAVIRT_SPINLOCKS 827 bool "Paravirtualization layer for spinlocks" 828 depends on PARAVIRT && SMP 829 help 830 Paravirtualized spinlocks allow a pvops backend to replace the 831 spinlock implementation with something virtualization-friendly 832 (for example, block the virtual CPU rather than spinning). 833 834 It has a minimal impact on native kernels and gives a nice performance 835 benefit on paravirtualized KVM / Xen kernels. 836 837 If you are unsure how to answer this question, answer Y. 838 839config X86_HV_CALLBACK_VECTOR 840 def_bool n 841 842source "arch/x86/xen/Kconfig" 843 844config KVM_GUEST 845 bool "KVM Guest support (including kvmclock)" 846 depends on PARAVIRT 847 select PARAVIRT_CLOCK 848 select ARCH_CPUIDLE_HALTPOLL 849 select X86_HV_CALLBACK_VECTOR 850 default y 851 help 852 This option enables various optimizations for running under the KVM 853 hypervisor. It includes a paravirtualized clock, so that instead 854 of relying on a PIT (or probably other) emulation by the 855 underlying device model, the host provides the guest with 856 timing infrastructure such as time of day, and system time 857 858config ARCH_CPUIDLE_HALTPOLL 859 def_bool n 860 prompt "Disable host haltpoll when loading haltpoll driver" 861 help 862 If virtualized under KVM, disable host haltpoll. 863 864config PVH 865 bool "Support for running PVH guests" 866 help 867 This option enables the PVH entry point for guest virtual machines 868 as specified in the x86/HVM direct boot ABI. 869 870config PARAVIRT_TIME_ACCOUNTING 871 bool "Paravirtual steal time accounting" 872 depends on PARAVIRT 873 help 874 Select this option to enable fine granularity task steal time 875 accounting. Time spent executing other tasks in parallel with 876 the current vCPU is discounted from the vCPU power. To account for 877 that, there can be a small performance impact. 878 879 If in doubt, say N here. 880 881config PARAVIRT_CLOCK 882 bool 883 884config JAILHOUSE_GUEST 885 bool "Jailhouse non-root cell support" 886 depends on X86_64 && PCI 887 select X86_PM_TIMER 888 help 889 This option allows to run Linux as guest in a Jailhouse non-root 890 cell. You can leave this option disabled if you only want to start 891 Jailhouse and run Linux afterwards in the root cell. 892 893config ACRN_GUEST 894 bool "ACRN Guest support" 895 depends on X86_64 896 select X86_HV_CALLBACK_VECTOR 897 help 898 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 899 a flexible, lightweight reference open-source hypervisor, built with 900 real-time and safety-criticality in mind. It is built for embedded 901 IOT with small footprint and real-time features. More details can be 902 found in https://projectacrn.org/. 903 904config BHYVE_GUEST 905 bool "Bhyve (BSD Hypervisor) Guest support" 906 depends on X86_64 907 help 908 This option allows to run Linux to recognise when it is running as a 909 guest in the Bhyve hypervisor, and to support more than 255 vCPUs when 910 when doing so. More details about Bhyve can be found at https://bhyve.org 911 and https://wiki.freebsd.org/bhyve/. 912 913config INTEL_TDX_GUEST 914 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 915 depends on X86_64 && CPU_SUP_INTEL 916 depends on X86_X2APIC 917 depends on EFI_STUB 918 depends on PARAVIRT 919 select ARCH_HAS_CC_PLATFORM 920 select X86_MEM_ENCRYPT 921 select X86_MCE 922 select UNACCEPTED_MEMORY 923 help 924 Support running as a guest under Intel TDX. Without this support, 925 the guest kernel can not boot or run under TDX. 926 TDX includes memory encryption and integrity capabilities 927 which protect the confidentiality and integrity of guest 928 memory contents and CPU state. TDX guests are protected from 929 some attacks from the VMM. 930 931endif # HYPERVISOR_GUEST 932 933source "arch/x86/Kconfig.cpu" 934 935config HPET_TIMER 936 def_bool X86_64 937 prompt "HPET Timer Support" if X86_32 938 help 939 Use the IA-PC HPET (High Precision Event Timer) to manage 940 time in preference to the PIT and RTC, if a HPET is 941 present. 942 HPET is the next generation timer replacing legacy 8254s. 943 The HPET provides a stable time base on SMP 944 systems, unlike the TSC, but it is more expensive to access, 945 as it is off-chip. The interface used is documented 946 in the HPET spec, revision 1. 947 948 You can safely choose Y here. However, HPET will only be 949 activated if the platform and the BIOS support this feature. 950 Otherwise the 8254 will be used for timing services. 951 952 Choose N to continue using the legacy 8254 timer. 953 954config HPET_EMULATE_RTC 955 def_bool y 956 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 957 958# Mark as expert because too many people got it wrong. 959# The code disables itself when not needed. 960config DMI 961 default y 962 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 963 bool "Enable DMI scanning" if EXPERT 964 help 965 Enabled scanning of DMI to identify machine quirks. Say Y 966 here unless you have verified that your setup is not 967 affected by entries in the DMI blacklist. Required by PNP 968 BIOS code. 969 970config GART_IOMMU 971 bool "Old AMD GART IOMMU support" 972 select IOMMU_HELPER 973 select SWIOTLB 974 depends on X86_64 && PCI && AMD_NB 975 help 976 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 977 GART based hardware IOMMUs. 978 979 The GART supports full DMA access for devices with 32-bit access 980 limitations, on systems with more than 3 GB. This is usually needed 981 for USB, sound, many IDE/SATA chipsets and some other devices. 982 983 Newer systems typically have a modern AMD IOMMU, supported via 984 the CONFIG_AMD_IOMMU=y config option. 985 986 In normal configurations this driver is only active when needed: 987 there's more than 3 GB of memory and the system contains a 988 32-bit limited device. 989 990 If unsure, say Y. 991 992config BOOT_VESA_SUPPORT 993 bool 994 help 995 If true, at least one selected framebuffer driver can take advantage 996 of VESA video modes set at an early boot stage via the vga= parameter. 997 998config MAXSMP 999 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 1000 depends on X86_64 && SMP && DEBUG_KERNEL 1001 select CPUMASK_OFFSTACK 1002 help 1003 Enable maximum number of CPUS and NUMA Nodes for this architecture. 1004 If unsure, say N. 1005 1006# 1007# The maximum number of CPUs supported: 1008# 1009# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 1010# and which can be configured interactively in the 1011# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 1012# 1013# The ranges are different on 32-bit and 64-bit kernels, depending on 1014# hardware capabilities and scalability features of the kernel. 1015# 1016# ( If MAXSMP is enabled we just use the highest possible value and disable 1017# interactive configuration. ) 1018# 1019 1020config NR_CPUS_RANGE_BEGIN 1021 int 1022 default NR_CPUS_RANGE_END if MAXSMP 1023 default 1 if !SMP 1024 default 2 1025 1026config NR_CPUS_RANGE_END 1027 int 1028 depends on X86_32 1029 default 8 if SMP 1030 default 1 if !SMP 1031 1032config NR_CPUS_RANGE_END 1033 int 1034 depends on X86_64 1035 default 8192 if SMP && CPUMASK_OFFSTACK 1036 default 512 if SMP && !CPUMASK_OFFSTACK 1037 default 1 if !SMP 1038 1039config NR_CPUS_DEFAULT 1040 int 1041 depends on X86_32 1042 default 8 if SMP 1043 default 1 if !SMP 1044 1045config NR_CPUS_DEFAULT 1046 int 1047 depends on X86_64 1048 default 8192 if MAXSMP 1049 default 64 if SMP 1050 default 1 if !SMP 1051 1052config NR_CPUS 1053 int "Maximum number of CPUs" if SMP && !MAXSMP 1054 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1055 default NR_CPUS_DEFAULT 1056 help 1057 This allows you to specify the maximum number of CPUs which this 1058 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1059 supported value is 8192, otherwise the maximum value is 512. The 1060 minimum value which makes sense is 2. 1061 1062 This is purely to save memory: each supported CPU adds about 8KB 1063 to the kernel image. 1064 1065config SCHED_MC_PRIO 1066 bool "CPU core priorities scheduler support" 1067 depends on SCHED_MC 1068 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1069 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1070 select CPU_FREQ 1071 default y 1072 help 1073 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1074 core ordering determined at manufacturing time, which allows 1075 certain cores to reach higher turbo frequencies (when running 1076 single threaded workloads) than others. 1077 1078 Enabling this kernel feature teaches the scheduler about 1079 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1080 scheduler's CPU selection logic accordingly, so that higher 1081 overall system performance can be achieved. 1082 1083 This feature will have no effect on CPUs without this feature. 1084 1085 If unsure say Y here. 1086 1087config UP_LATE_INIT 1088 def_bool y 1089 depends on !SMP && X86_LOCAL_APIC 1090 1091config X86_UP_APIC 1092 bool "Local APIC support on uniprocessors" if !PCI_MSI 1093 default PCI_MSI 1094 depends on X86_32 && !SMP 1095 help 1096 A local APIC (Advanced Programmable Interrupt Controller) is an 1097 integrated interrupt controller in the CPU. If you have a single-CPU 1098 system which has a processor with a local APIC, you can say Y here to 1099 enable and use it. If you say Y here even though your machine doesn't 1100 have a local APIC, then the kernel will still run with no slowdown at 1101 all. The local APIC supports CPU-generated self-interrupts (timer, 1102 performance counters), and the NMI watchdog which detects hard 1103 lockups. 1104 1105config X86_UP_IOAPIC 1106 bool "IO-APIC support on uniprocessors" 1107 depends on X86_UP_APIC 1108 help 1109 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1110 SMP-capable replacement for PC-style interrupt controllers. Most 1111 SMP systems and many recent uniprocessor systems have one. 1112 1113 If you have a single-CPU system with an IO-APIC, you can say Y here 1114 to use it. If you say Y here even though your machine doesn't have 1115 an IO-APIC, then the kernel will still run with no slowdown at all. 1116 1117config X86_LOCAL_APIC 1118 def_bool y 1119 depends on X86_64 || SMP || X86_UP_APIC || PCI_MSI 1120 select IRQ_DOMAIN_HIERARCHY 1121 1122config ACPI_MADT_WAKEUP 1123 def_bool y 1124 depends on X86_64 1125 depends on ACPI 1126 depends on SMP 1127 depends on X86_LOCAL_APIC 1128 1129config X86_IO_APIC 1130 def_bool y 1131 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1132 1133config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1134 bool "Reroute for broken boot IRQs" 1135 depends on X86_IO_APIC 1136 help 1137 This option enables a workaround that fixes a source of 1138 spurious interrupts. This is recommended when threaded 1139 interrupt handling is used on systems where the generation of 1140 superfluous "boot interrupts" cannot be disabled. 1141 1142 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1143 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1144 kernel does during interrupt handling). On chipsets where this 1145 boot IRQ generation cannot be disabled, this workaround keeps 1146 the original IRQ line masked so that only the equivalent "boot 1147 IRQ" is delivered to the CPUs. The workaround also tells the 1148 kernel to set up the IRQ handler on the boot IRQ line. In this 1149 way only one interrupt is delivered to the kernel. Otherwise 1150 the spurious second interrupt may cause the kernel to bring 1151 down (vital) interrupt lines. 1152 1153 Only affects "broken" chipsets. Interrupt sharing may be 1154 increased on these systems. 1155 1156config X86_MCE 1157 bool "Machine Check / overheating reporting" 1158 select GENERIC_ALLOCATOR 1159 default y 1160 help 1161 Machine Check support allows the processor to notify the 1162 kernel if it detects a problem (e.g. overheating, data corruption). 1163 The action the kernel takes depends on the severity of the problem, 1164 ranging from warning messages to halting the machine. 1165 1166config X86_MCELOG_LEGACY 1167 bool "Support for deprecated /dev/mcelog character device" 1168 depends on X86_MCE 1169 help 1170 Enable support for /dev/mcelog which is needed by the old mcelog 1171 userspace logging daemon. Consider switching to the new generation 1172 rasdaemon solution. 1173 1174config X86_MCE_INTEL 1175 def_bool y 1176 prompt "Intel MCE features" 1177 depends on X86_MCE && X86_LOCAL_APIC 1178 help 1179 Additional support for intel specific MCE features such as 1180 the thermal monitor. 1181 1182config X86_MCE_AMD 1183 def_bool y 1184 prompt "AMD MCE features" 1185 depends on X86_MCE && X86_LOCAL_APIC 1186 help 1187 Additional support for AMD specific MCE features such as 1188 the DRAM Error Threshold. 1189 1190config X86_ANCIENT_MCE 1191 bool "Support for old Pentium 5 / WinChip machine checks" 1192 depends on X86_32 && X86_MCE 1193 help 1194 Include support for machine check handling on old Pentium 5 or WinChip 1195 systems. These typically need to be enabled explicitly on the command 1196 line. 1197 1198config X86_MCE_THRESHOLD 1199 depends on X86_MCE_AMD || X86_MCE_INTEL 1200 def_bool y 1201 1202config X86_MCE_INJECT 1203 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1204 tristate "Machine check injector support" 1205 help 1206 Provide support for injecting machine checks for testing purposes. 1207 If you don't know what a machine check is and you don't do kernel 1208 QA it is safe to say n. 1209 1210source "arch/x86/events/Kconfig" 1211 1212config X86_LEGACY_VM86 1213 bool "Legacy VM86 support" 1214 depends on X86_32 1215 help 1216 This option allows user programs to put the CPU into V8086 1217 mode, which is an 80286-era approximation of 16-bit real mode. 1218 1219 Some very old versions of X and/or vbetool require this option 1220 for user mode setting. Similarly, DOSEMU will use it if 1221 available to accelerate real mode DOS programs. However, any 1222 recent version of DOSEMU, X, or vbetool should be fully 1223 functional even without kernel VM86 support, as they will all 1224 fall back to software emulation. Nevertheless, if you are using 1225 a 16-bit DOS program where 16-bit performance matters, vm86 1226 mode might be faster than emulation and you might want to 1227 enable this option. 1228 1229 Note that any app that works on a 64-bit kernel is unlikely to 1230 need this option, as 64-bit kernels don't, and can't, support 1231 V8086 mode. This option is also unrelated to 16-bit protected 1232 mode and is not needed to run most 16-bit programs under Wine. 1233 1234 Enabling this option increases the complexity of the kernel 1235 and slows down exception handling a tiny bit. 1236 1237 If unsure, say N here. 1238 1239config VM86 1240 bool 1241 default X86_LEGACY_VM86 1242 1243config X86_16BIT 1244 bool "Enable support for 16-bit segments" if EXPERT 1245 default y 1246 depends on MODIFY_LDT_SYSCALL 1247 help 1248 This option is required by programs like Wine to run 16-bit 1249 protected mode legacy code on x86 processors. Disabling 1250 this option saves about 300 bytes on i386, or around 6K text 1251 plus 16K runtime memory on x86-64, 1252 1253config X86_ESPFIX32 1254 def_bool y 1255 depends on X86_16BIT && X86_32 1256 1257config X86_ESPFIX64 1258 def_bool y 1259 depends on X86_16BIT && X86_64 1260 1261config X86_VSYSCALL_EMULATION 1262 bool "Enable vsyscall emulation" if EXPERT 1263 default y 1264 depends on X86_64 1265 help 1266 This enables emulation of the legacy vsyscall page. Disabling 1267 it is roughly equivalent to booting with vsyscall=none, except 1268 that it will also disable the helpful warning if a program 1269 tries to use a vsyscall. With this option set to N, offending 1270 programs will just segfault, citing addresses of the form 1271 0xffffffffff600?00. 1272 1273 This option is required by many programs built before 2013, and 1274 care should be used even with newer programs if set to N. 1275 1276 Disabling this option saves about 7K of kernel size and 1277 possibly 4K of additional runtime pagetable memory. 1278 1279config X86_IOPL_IOPERM 1280 bool "IOPERM and IOPL Emulation" 1281 default y 1282 help 1283 This enables the ioperm() and iopl() syscalls which are necessary 1284 for legacy applications. 1285 1286 Legacy IOPL support is an overbroad mechanism which allows user 1287 space aside of accessing all 65536 I/O ports also to disable 1288 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1289 capabilities and permission from potentially active security 1290 modules. 1291 1292 The emulation restricts the functionality of the syscall to 1293 only allowing the full range I/O port access, but prevents the 1294 ability to disable interrupts from user space which would be 1295 granted if the hardware IOPL mechanism would be used. 1296 1297config TOSHIBA 1298 tristate "Toshiba Laptop support" 1299 depends on X86_32 1300 help 1301 This adds a driver to safely access the System Management Mode of 1302 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1303 not work on models with a Phoenix BIOS. The System Management Mode 1304 is used to set the BIOS and power saving options on Toshiba portables. 1305 1306 For information on utilities to make use of this driver see the 1307 Toshiba Linux utilities web site at: 1308 <http://www.buzzard.org.uk/toshiba/>. 1309 1310 Say Y if you intend to run this kernel on a Toshiba portable. 1311 Say N otherwise. 1312 1313config X86_REBOOTFIXUPS 1314 bool "Enable X86 board specific fixups for reboot" 1315 depends on X86_32 1316 help 1317 This enables chipset and/or board specific fixups to be done 1318 in order to get reboot to work correctly. This is only needed on 1319 some combinations of hardware and BIOS. The symptom, for which 1320 this config is intended, is when reboot ends with a stalled/hung 1321 system. 1322 1323 Currently, the only fixup is for the Geode machines using 1324 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1325 1326 Say Y if you want to enable the fixup. Currently, it's safe to 1327 enable this option even if you don't need it. 1328 Say N otherwise. 1329 1330config MICROCODE 1331 def_bool y 1332 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1333 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD 1334 1335config MICROCODE_INITRD32 1336 def_bool y 1337 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1338 1339config MICROCODE_LATE_LOADING 1340 bool "Late microcode loading (DANGEROUS)" 1341 default n 1342 depends on MICROCODE && SMP 1343 help 1344 Loading microcode late, when the system is up and executing instructions 1345 is a tricky business and should be avoided if possible. Just the sequence 1346 of synchronizing all cores and SMT threads is one fragile dance which does 1347 not guarantee that cores might not softlock after the loading. Therefore, 1348 use this at your own risk. Late loading taints the kernel unless the 1349 microcode header indicates that it is safe for late loading via the 1350 minimal revision check. This minimal revision check can be enforced on 1351 the kernel command line with "microcode=force_minrev". 1352 1353config MICROCODE_LATE_FORCE_MINREV 1354 bool "Enforce late microcode loading minimal revision check" 1355 default n 1356 depends on MICROCODE_LATE_LOADING 1357 help 1358 To prevent that users load microcode late which modifies already 1359 in use features, newer microcode patches have a minimum revision field 1360 in the microcode header, which tells the kernel which minimum 1361 revision must be active in the CPU to safely load that new microcode 1362 late into the running system. If disabled the check will not 1363 be enforced but the kernel will be tainted when the minimal 1364 revision check fails. 1365 1366 This minimal revision check can also be controlled via the 1367 "microcode=force_minrev" parameter on the kernel command line. 1368 1369 If unsure say Y. 1370 1371config MICROCODE_DBG 1372 bool "Enable microcode loader debugging" 1373 default n 1374 depends on MICROCODE 1375 help 1376 Enable code which allows to debug the microcode loader. When running 1377 in a guest the patch loading is simulated but everything else 1378 related to patch parsing and handling is done as on baremetal with 1379 the purpose of debugging solely the software side of things. On 1380 baremetal, it simply dumps additional debugging information during 1381 normal operation. 1382 1383 You almost certainly want to say n here. 1384 1385config X86_MSR 1386 tristate "/dev/cpu/*/msr - Model-specific register support" 1387 help 1388 This device gives privileged processes access to the x86 1389 Model-Specific Registers (MSRs). It is a character device with 1390 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1391 MSR accesses are directed to a specific CPU on multi-processor 1392 systems. 1393 1394config X86_CPUID 1395 tristate "/dev/cpu/*/cpuid - CPU information support" 1396 help 1397 This device gives processes access to the x86 CPUID instruction to 1398 be executed on a specific processor. It is a character device 1399 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1400 /dev/cpu/31/cpuid. 1401 1402config HIGHMEM4G 1403 bool "High Memory Support" 1404 depends on X86_32 1405 help 1406 Linux can use up to 4 Gigabytes of physical memory on x86 systems. 1407 However, the address space of 32-bit x86 processors is only 4 1408 Gigabytes large. That means that, if you have a large amount of 1409 physical memory, not all of it can be "permanently mapped" by the 1410 kernel. The physical memory that's not permanently mapped is called 1411 "high memory". 1412 1413 If you are compiling a kernel which will never run on a machine with 1414 more than 1 Gigabyte total physical RAM, answer "off" here (default 1415 choice and suitable for most users). This will result in a "3GB/1GB" 1416 split: 3GB are mapped so that each process sees a 3GB virtual memory 1417 space and the remaining part of the 4GB virtual memory space is used 1418 by the kernel to permanently map as much physical memory as 1419 possible. 1420 1421 If the machine has between 1 and 4 Gigabytes physical RAM, then 1422 answer "Y" here. 1423 1424 If unsure, say N. 1425 1426choice 1427 prompt "Memory split" if EXPERT 1428 default VMSPLIT_3G 1429 depends on X86_32 1430 help 1431 Select the desired split between kernel and user memory. 1432 1433 If the address range available to the kernel is less than the 1434 physical memory installed, the remaining memory will be available 1435 as "high memory". Accessing high memory is a little more costly 1436 than low memory, as it needs to be mapped into the kernel first. 1437 Note that increasing the kernel address space limits the range 1438 available to user programs, making the address space there 1439 tighter. Selecting anything other than the default 3G/1G split 1440 will also likely make your kernel incompatible with binary-only 1441 kernel modules. 1442 1443 If you are not absolutely sure what you are doing, leave this 1444 option alone! 1445 1446 config VMSPLIT_3G 1447 bool "3G/1G user/kernel split" 1448 config VMSPLIT_3G_OPT 1449 depends on !X86_PAE 1450 bool "3G/1G user/kernel split (for full 1G low memory)" 1451 config VMSPLIT_2G 1452 bool "2G/2G user/kernel split" 1453 config VMSPLIT_2G_OPT 1454 depends on !X86_PAE 1455 bool "2G/2G user/kernel split (for full 2G low memory)" 1456 config VMSPLIT_1G 1457 bool "1G/3G user/kernel split" 1458endchoice 1459 1460config PAGE_OFFSET 1461 hex 1462 default 0xB0000000 if VMSPLIT_3G_OPT 1463 default 0x80000000 if VMSPLIT_2G 1464 default 0x78000000 if VMSPLIT_2G_OPT 1465 default 0x40000000 if VMSPLIT_1G 1466 default 0xC0000000 1467 depends on X86_32 1468 1469config HIGHMEM 1470 def_bool HIGHMEM4G 1471 1472config X86_PAE 1473 bool "PAE (Physical Address Extension) Support" 1474 depends on X86_32 && X86_HAVE_PAE 1475 select PHYS_ADDR_T_64BIT 1476 help 1477 PAE is required for NX support, and furthermore enables 1478 larger swapspace support for non-overcommit purposes. It 1479 has the cost of more pagetable lookup overhead, and also 1480 consumes more pagetable space per process. 1481 1482config X86_DIRECT_GBPAGES 1483 def_bool y 1484 depends on X86_64 1485 help 1486 Certain kernel features effectively disable kernel 1487 linear 1 GB mappings (even if the CPU otherwise 1488 supports them), so don't confuse the user by printing 1489 that we have them enabled. 1490 1491config X86_CPA_STATISTICS 1492 bool "Enable statistic for Change Page Attribute" 1493 depends on DEBUG_FS 1494 help 1495 Expose statistics about the Change Page Attribute mechanism, which 1496 helps to determine the effectiveness of preserving large and huge 1497 page mappings when mapping protections are changed. 1498 1499config X86_MEM_ENCRYPT 1500 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1501 select DYNAMIC_PHYSICAL_MASK 1502 def_bool n 1503 1504config AMD_MEM_ENCRYPT 1505 bool "AMD Secure Memory Encryption (SME) support" 1506 depends on X86_64 && CPU_SUP_AMD 1507 depends on EFI_STUB 1508 select DMA_COHERENT_POOL 1509 select ARCH_USE_MEMREMAP_PROT 1510 select INSTRUCTION_DECODER 1511 select ARCH_HAS_CC_PLATFORM 1512 select X86_MEM_ENCRYPT 1513 select UNACCEPTED_MEMORY 1514 select CRYPTO_LIB_AESGCM 1515 help 1516 Say yes to enable support for the encryption of system memory. 1517 This requires an AMD processor that supports Secure Memory 1518 Encryption (SME). 1519 1520# Common NUMA Features 1521config NUMA 1522 bool "NUMA Memory Allocation and Scheduler Support" 1523 depends on SMP 1524 depends on X86_64 1525 select USE_PERCPU_NUMA_NODE_ID 1526 select OF_NUMA if OF 1527 help 1528 Enable NUMA (Non-Uniform Memory Access) support. 1529 1530 The kernel will try to allocate memory used by a CPU on the 1531 local memory controller of the CPU and add some more 1532 NUMA awareness to the kernel. 1533 1534 For 64-bit this is recommended if the system is Intel Core i7 1535 (or later), AMD Opteron, or EM64T NUMA. 1536 1537 Otherwise, you should say N. 1538 1539config AMD_NUMA 1540 def_bool y 1541 prompt "Old style AMD Opteron NUMA detection" 1542 depends on X86_64 && NUMA && PCI 1543 help 1544 Enable AMD NUMA node topology detection. You should say Y here if 1545 you have a multi processor AMD system. This uses an old method to 1546 read the NUMA configuration directly from the builtin Northbridge 1547 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1548 which also takes priority if both are compiled in. 1549 1550config X86_64_ACPI_NUMA 1551 def_bool y 1552 prompt "ACPI NUMA detection" 1553 depends on X86_64 && NUMA && ACPI && PCI 1554 select ACPI_NUMA 1555 help 1556 Enable ACPI SRAT based node topology detection. 1557 1558config NODES_SHIFT 1559 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1560 range 1 10 1561 default "10" if MAXSMP 1562 default "6" if X86_64 1563 default "3" 1564 depends on NUMA 1565 help 1566 Specify the maximum number of NUMA Nodes available on the target 1567 system. Increases memory reserved to accommodate various tables. 1568 1569config ARCH_FLATMEM_ENABLE 1570 def_bool y 1571 depends on X86_32 && !NUMA 1572 1573config ARCH_SPARSEMEM_ENABLE 1574 def_bool y 1575 select SPARSEMEM_STATIC if X86_32 1576 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1577 1578config ARCH_SPARSEMEM_DEFAULT 1579 def_bool X86_64 || (NUMA && X86_32) 1580 1581config ARCH_SELECT_MEMORY_MODEL 1582 def_bool y 1583 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1584 1585config ARCH_MEMORY_PROBE 1586 bool "Enable sysfs memory/probe interface" 1587 depends on MEMORY_HOTPLUG 1588 help 1589 This option enables a sysfs memory/probe interface for testing. 1590 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1591 If you are unsure how to answer this question, answer N. 1592 1593config ARCH_PROC_KCORE_TEXT 1594 def_bool y 1595 depends on X86_64 && PROC_KCORE 1596 1597config ILLEGAL_POINTER_VALUE 1598 hex 1599 default 0 if X86_32 1600 default 0xdead000000000000 if X86_64 1601 1602config X86_PMEM_LEGACY_DEVICE 1603 bool 1604 1605config X86_PMEM_LEGACY 1606 tristate "Support non-standard NVDIMMs and ADR protected memory" 1607 depends on PHYS_ADDR_T_64BIT 1608 depends on BLK_DEV 1609 select X86_PMEM_LEGACY_DEVICE 1610 select NUMA_KEEP_MEMINFO if NUMA 1611 select LIBNVDIMM 1612 help 1613 Treat memory marked using the non-standard e820 type of 12 as used 1614 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1615 The kernel will offer these regions to the 'pmem' driver so 1616 they can be used for persistent storage. 1617 1618 Say Y if unsure. 1619 1620config X86_CHECK_BIOS_CORRUPTION 1621 bool "Check for low memory corruption" 1622 help 1623 Periodically check for memory corruption in low memory, which 1624 is suspected to be caused by BIOS. Even when enabled in the 1625 configuration, it is disabled at runtime. Enable it by 1626 setting "memory_corruption_check=1" on the kernel command 1627 line. By default it scans the low 64k of memory every 60 1628 seconds; see the memory_corruption_check_size and 1629 memory_corruption_check_period parameters in 1630 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1631 1632 When enabled with the default parameters, this option has 1633 almost no overhead, as it reserves a relatively small amount 1634 of memory and scans it infrequently. It both detects corruption 1635 and prevents it from affecting the running system. 1636 1637 It is, however, intended as a diagnostic tool; if repeatable 1638 BIOS-originated corruption always affects the same memory, 1639 you can use memmap= to prevent the kernel from using that 1640 memory. 1641 1642config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1643 bool "Set the default setting of memory_corruption_check" 1644 depends on X86_CHECK_BIOS_CORRUPTION 1645 default y 1646 help 1647 Set whether the default state of memory_corruption_check is 1648 on or off. 1649 1650config MATH_EMULATION 1651 bool 1652 depends on MODIFY_LDT_SYSCALL 1653 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1654 help 1655 Linux can emulate a math coprocessor (used for floating point 1656 operations) if you don't have one. 486DX and Pentium processors have 1657 a math coprocessor built in, 486SX and 386 do not, unless you added 1658 a 487DX or 387, respectively. (The messages during boot time can 1659 give you some hints here ["man dmesg"].) Everyone needs either a 1660 coprocessor or this emulation. 1661 1662 If you don't have a math coprocessor, you need to say Y here; if you 1663 say Y here even though you have a coprocessor, the coprocessor will 1664 be used nevertheless. (This behavior can be changed with the kernel 1665 command line option "no387", which comes handy if your coprocessor 1666 is broken. Try "man bootparam" or see the documentation of your boot 1667 loader (lilo or loadlin) about how to pass options to the kernel at 1668 boot time.) This means that it is a good idea to say Y here if you 1669 intend to use this kernel on different machines. 1670 1671 More information about the internals of the Linux math coprocessor 1672 emulation can be found in <file:arch/x86/math-emu/README>. 1673 1674 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1675 kernel, it won't hurt. 1676 1677config MTRR 1678 def_bool y 1679 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1680 help 1681 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1682 the Memory Type Range Registers (MTRRs) may be used to control 1683 processor access to memory ranges. This is most useful if you have 1684 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1685 allows bus write transfers to be combined into a larger transfer 1686 before bursting over the PCI/AGP bus. This can increase performance 1687 of image write operations 2.5 times or more. Saying Y here creates a 1688 /proc/mtrr file which may be used to manipulate your processor's 1689 MTRRs. Typically the X server should use this. 1690 1691 This code has a reasonably generic interface so that similar 1692 control registers on other processors can be easily supported 1693 as well: 1694 1695 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1696 Registers (ARRs) which provide a similar functionality to MTRRs. For 1697 these, the ARRs are used to emulate the MTRRs. 1698 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1699 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1700 write-combining. All of these processors are supported by this code 1701 and it makes sense to say Y here if you have one of them. 1702 1703 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1704 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1705 can lead to all sorts of problems, so it's good to say Y here. 1706 1707 You can safely say Y even if your machine doesn't have MTRRs, you'll 1708 just add about 9 KB to your kernel. 1709 1710 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1711 1712config MTRR_SANITIZER 1713 def_bool y 1714 prompt "MTRR cleanup support" 1715 depends on MTRR 1716 help 1717 Convert MTRR layout from continuous to discrete, so X drivers can 1718 add writeback entries. 1719 1720 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1721 The largest mtrr entry size for a continuous block can be set with 1722 mtrr_chunk_size. 1723 1724 If unsure, say Y. 1725 1726config MTRR_SANITIZER_ENABLE_DEFAULT 1727 int "MTRR cleanup enable value (0-1)" 1728 range 0 1 1729 default "0" 1730 depends on MTRR_SANITIZER 1731 help 1732 Enable mtrr cleanup default value 1733 1734config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1735 int "MTRR cleanup spare reg num (0-7)" 1736 range 0 7 1737 default "1" 1738 depends on MTRR_SANITIZER 1739 help 1740 mtrr cleanup spare entries default, it can be changed via 1741 mtrr_spare_reg_nr=N on the kernel command line. 1742 1743config X86_PAT 1744 def_bool y 1745 prompt "x86 PAT support" if EXPERT 1746 depends on MTRR 1747 select ARCH_USES_PG_ARCH_2 1748 help 1749 Use PAT attributes to setup page level cache control. 1750 1751 PATs are the modern equivalents of MTRRs and are much more 1752 flexible than MTRRs. 1753 1754 Say N here if you see bootup problems (boot crash, boot hang, 1755 spontaneous reboots) or a non-working video driver. 1756 1757 If unsure, say Y. 1758 1759config X86_UMIP 1760 def_bool y 1761 prompt "User Mode Instruction Prevention" if EXPERT 1762 help 1763 User Mode Instruction Prevention (UMIP) is a security feature in 1764 some x86 processors. If enabled, a general protection fault is 1765 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1766 executed in user mode. These instructions unnecessarily expose 1767 information about the hardware state. 1768 1769 The vast majority of applications do not use these instructions. 1770 For the very few that do, software emulation is provided in 1771 specific cases in protected and virtual-8086 modes. Emulated 1772 results are dummy. 1773 1774config CC_HAS_IBT 1775 # GCC >= 9 and binutils >= 2.29 1776 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1777 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || CC_IS_CLANG) && \ 1778 $(as-instr,endbr64) 1779 1780config X86_CET 1781 def_bool n 1782 help 1783 CET features configured (Shadow stack or IBT) 1784 1785config X86_KERNEL_IBT 1786 prompt "Indirect Branch Tracking" 1787 def_bool y 1788 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1789 select OBJTOOL 1790 select X86_CET 1791 help 1792 Build the kernel with support for Indirect Branch Tracking, a 1793 hardware support course-grain forward-edge Control Flow Integrity 1794 protection. It enforces that all indirect calls must land on 1795 an ENDBR instruction, as such, the compiler will instrument the 1796 code with them to make this happen. 1797 1798 In addition to building the kernel with IBT, seal all functions that 1799 are not indirect call targets, avoiding them ever becoming one. 1800 1801 This requires LTO like objtool runs and will slow down the build. It 1802 does significantly reduce the number of ENDBR instructions in the 1803 kernel image. 1804 1805config X86_INTEL_MEMORY_PROTECTION_KEYS 1806 prompt "Memory Protection Keys" 1807 def_bool y 1808 # Note: only available in 64-bit mode 1809 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1810 select ARCH_USES_HIGH_VMA_FLAGS 1811 select ARCH_HAS_PKEYS 1812 help 1813 Memory Protection Keys provides a mechanism for enforcing 1814 page-based protections, but without requiring modification of the 1815 page tables when an application changes protection domains. 1816 1817 For details, see Documentation/core-api/protection-keys.rst 1818 1819 If unsure, say y. 1820 1821config ARCH_PKEY_BITS 1822 int 1823 default 4 1824 1825choice 1826 prompt "TSX enable mode" 1827 depends on CPU_SUP_INTEL 1828 default X86_INTEL_TSX_MODE_AUTO 1829 help 1830 Intel's TSX (Transactional Synchronization Extensions) feature 1831 allows to optimize locking protocols through lock elision which 1832 can lead to a noticeable performance boost. 1833 1834 On the other hand it has been shown that TSX can be exploited 1835 to form side channel attacks (e.g. TAA) and chances are there 1836 will be more of those attacks discovered in the future. 1837 1838 Therefore TSX is not enabled by default (aka tsx=off). An admin 1839 might override this decision by tsx=on the command line parameter. 1840 Even with TSX enabled, the kernel will attempt to enable the best 1841 possible TAA mitigation setting depending on the microcode available 1842 for the particular machine. 1843 1844 This option allows to set the default tsx mode between tsx=on, =off 1845 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1846 details. 1847 1848 Say off if not sure, auto if TSX is in use but it should be used on safe 1849 platforms or on if TSX is in use and the security aspect of tsx is not 1850 relevant. 1851 1852config X86_INTEL_TSX_MODE_OFF 1853 bool "off" 1854 help 1855 TSX is disabled if possible - equals to tsx=off command line parameter. 1856 1857config X86_INTEL_TSX_MODE_ON 1858 bool "on" 1859 help 1860 TSX is always enabled on TSX capable HW - equals the tsx=on command 1861 line parameter. 1862 1863config X86_INTEL_TSX_MODE_AUTO 1864 bool "auto" 1865 help 1866 TSX is enabled on TSX capable HW that is believed to be safe against 1867 side channel attacks- equals the tsx=auto command line parameter. 1868endchoice 1869 1870config X86_SGX 1871 bool "Software Guard eXtensions (SGX)" 1872 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1873 select CRYPTO_LIB_SHA256 1874 select MMU_NOTIFIER 1875 select NUMA_KEEP_MEMINFO if NUMA 1876 select XARRAY_MULTI 1877 help 1878 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1879 that can be used by applications to set aside private regions of code 1880 and data, referred to as enclaves. An enclave's private memory can 1881 only be accessed by code running within the enclave. Accesses from 1882 outside the enclave, including other enclaves, are disallowed by 1883 hardware. 1884 1885 If unsure, say N. 1886 1887config X86_USER_SHADOW_STACK 1888 bool "X86 userspace shadow stack" 1889 depends on AS_WRUSS 1890 depends on X86_64 1891 select ARCH_USES_HIGH_VMA_FLAGS 1892 select ARCH_HAS_USER_SHADOW_STACK 1893 select X86_CET 1894 help 1895 Shadow stack protection is a hardware feature that detects function 1896 return address corruption. This helps mitigate ROP attacks. 1897 Applications must be enabled to use it, and old userspace does not 1898 get protection "for free". 1899 1900 CPUs supporting shadow stacks were first released in 2020. 1901 1902 See Documentation/arch/x86/shstk.rst for more information. 1903 1904 If unsure, say N. 1905 1906config INTEL_TDX_HOST 1907 bool "Intel Trust Domain Extensions (TDX) host support" 1908 depends on CPU_SUP_INTEL 1909 depends on X86_64 1910 depends on KVM_INTEL 1911 depends on X86_X2APIC 1912 select ARCH_KEEP_MEMBLOCK 1913 depends on CONTIG_ALLOC 1914 depends on X86_MCE 1915 help 1916 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1917 host and certain physical attacks. This option enables necessary TDX 1918 support in the host kernel to run confidential VMs. 1919 1920 If unsure, say N. 1921 1922config EFI 1923 bool "EFI runtime service support" 1924 depends on ACPI 1925 select UCS2_STRING 1926 select EFI_RUNTIME_WRAPPERS 1927 select ARCH_USE_MEMREMAP_PROT 1928 select EFI_RUNTIME_MAP if KEXEC_CORE 1929 help 1930 This enables the kernel to use EFI runtime services that are 1931 available (such as the EFI variable services). 1932 1933 This option is only useful on systems that have EFI firmware. 1934 In addition, you should use the latest ELILO loader available 1935 at <http://elilo.sourceforge.net> in order to take advantage 1936 of EFI runtime services. However, even with this option, the 1937 resultant kernel should continue to boot on existing non-EFI 1938 platforms. 1939 1940config EFI_STUB 1941 bool "EFI stub support" 1942 depends on EFI 1943 select RELOCATABLE 1944 help 1945 This kernel feature allows a bzImage to be loaded directly 1946 by EFI firmware without the use of a bootloader. 1947 1948 See Documentation/admin-guide/efi-stub.rst for more information. 1949 1950config EFI_HANDOVER_PROTOCOL 1951 bool "EFI handover protocol (DEPRECATED)" 1952 depends on EFI_STUB 1953 default y 1954 help 1955 Select this in order to include support for the deprecated EFI 1956 handover protocol, which defines alternative entry points into the 1957 EFI stub. This is a practice that has no basis in the UEFI 1958 specification, and requires a priori knowledge on the part of the 1959 bootloader about Linux/x86 specific ways of passing the command line 1960 and initrd, and where in memory those assets may be loaded. 1961 1962 If in doubt, say Y. Even though the corresponding support is not 1963 present in upstream GRUB or other bootloaders, most distros build 1964 GRUB with numerous downstream patches applied, and may rely on the 1965 handover protocol as as result. 1966 1967config EFI_MIXED 1968 bool "EFI mixed-mode support" 1969 depends on EFI_STUB && X86_64 1970 help 1971 Enabling this feature allows a 64-bit kernel to be booted 1972 on a 32-bit firmware, provided that your CPU supports 64-bit 1973 mode. 1974 1975 Note that it is not possible to boot a mixed-mode enabled 1976 kernel via the EFI boot stub - a bootloader that supports 1977 the EFI handover protocol must be used. 1978 1979 If unsure, say N. 1980 1981config EFI_RUNTIME_MAP 1982 bool "Export EFI runtime maps to sysfs" if EXPERT 1983 depends on EFI 1984 help 1985 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 1986 That memory map is required by the 2nd kernel to set up EFI virtual 1987 mappings after kexec, but can also be used for debugging purposes. 1988 1989 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 1990 1991source "kernel/Kconfig.hz" 1992 1993config ARCH_SUPPORTS_KEXEC 1994 def_bool y 1995 1996config ARCH_SUPPORTS_KEXEC_FILE 1997 def_bool X86_64 1998 1999config ARCH_SELECTS_KEXEC_FILE 2000 def_bool y 2001 depends on KEXEC_FILE 2002 select HAVE_IMA_KEXEC if IMA 2003 2004config ARCH_SUPPORTS_KEXEC_PURGATORY 2005 def_bool y 2006 2007config ARCH_SUPPORTS_KEXEC_SIG 2008 def_bool y 2009 2010config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2011 def_bool y 2012 2013config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2014 def_bool y 2015 2016config ARCH_SUPPORTS_KEXEC_JUMP 2017 def_bool y 2018 2019config ARCH_SUPPORTS_KEXEC_HANDOVER 2020 def_bool X86_64 2021 2022config ARCH_SUPPORTS_CRASH_DUMP 2023 def_bool X86_64 || (X86_32 && HIGHMEM) 2024 2025config ARCH_DEFAULT_CRASH_DUMP 2026 def_bool y 2027 2028config ARCH_SUPPORTS_CRASH_HOTPLUG 2029 def_bool y 2030 2031config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2032 def_bool CRASH_RESERVE 2033 2034config PHYSICAL_START 2035 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2036 default "0x1000000" 2037 help 2038 This gives the physical address where the kernel is loaded. 2039 2040 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2041 will decompress itself to above physical address and run from there. 2042 Otherwise, bzImage will run from the address where it has been loaded 2043 by the boot loader. The only exception is if it is loaded below the 2044 above physical address, in which case it will relocate itself there. 2045 2046 In normal kdump cases one does not have to set/change this option 2047 as now bzImage can be compiled as a completely relocatable image 2048 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2049 address. This option is mainly useful for the folks who don't want 2050 to use a bzImage for capturing the crash dump and want to use a 2051 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2052 to be specifically compiled to run from a specific memory area 2053 (normally a reserved region) and this option comes handy. 2054 2055 So if you are using bzImage for capturing the crash dump, 2056 leave the value here unchanged to 0x1000000 and set 2057 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2058 for capturing the crash dump change this value to start of 2059 the reserved region. In other words, it can be set based on 2060 the "X" value as specified in the "crashkernel=YM@XM" 2061 command line boot parameter passed to the panic-ed 2062 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2063 for more details about crash dumps. 2064 2065 Usage of bzImage for capturing the crash dump is recommended as 2066 one does not have to build two kernels. Same kernel can be used 2067 as production kernel and capture kernel. Above option should have 2068 gone away after relocatable bzImage support is introduced. But it 2069 is present because there are users out there who continue to use 2070 vmlinux for dump capture. This option should go away down the 2071 line. 2072 2073 Don't change this unless you know what you are doing. 2074 2075config RELOCATABLE 2076 bool "Build a relocatable kernel" 2077 default y 2078 help 2079 This builds a kernel image that retains relocation information 2080 so it can be loaded someplace besides the default 1MB. 2081 The relocations tend to make the kernel binary about 10% larger, 2082 but are discarded at runtime. 2083 2084 One use is for the kexec on panic case where the recovery kernel 2085 must live at a different physical address than the primary 2086 kernel. 2087 2088 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2089 it has been loaded at and the compile time physical address 2090 (CONFIG_PHYSICAL_START) is used as the minimum location. 2091 2092config RANDOMIZE_BASE 2093 bool "Randomize the address of the kernel image (KASLR)" 2094 depends on RELOCATABLE 2095 default y 2096 help 2097 In support of Kernel Address Space Layout Randomization (KASLR), 2098 this randomizes the physical address at which the kernel image 2099 is decompressed and the virtual address where the kernel 2100 image is mapped, as a security feature that deters exploit 2101 attempts relying on knowledge of the location of kernel 2102 code internals. 2103 2104 On 64-bit, the kernel physical and virtual addresses are 2105 randomized separately. The physical address will be anywhere 2106 between 16MB and the top of physical memory (up to 64TB). The 2107 virtual address will be randomized from 16MB up to 1GB (9 bits 2108 of entropy). Note that this also reduces the memory space 2109 available to kernel modules from 1.5GB to 1GB. 2110 2111 On 32-bit, the kernel physical and virtual addresses are 2112 randomized together. They will be randomized from 16MB up to 2113 512MB (8 bits of entropy). 2114 2115 Entropy is generated using the RDRAND instruction if it is 2116 supported. If RDTSC is supported, its value is mixed into 2117 the entropy pool as well. If neither RDRAND nor RDTSC are 2118 supported, then entropy is read from the i8254 timer. The 2119 usable entropy is limited by the kernel being built using 2120 2GB addressing, and that PHYSICAL_ALIGN must be at a 2121 minimum of 2MB. As a result, only 10 bits of entropy are 2122 theoretically possible, but the implementations are further 2123 limited due to memory layouts. 2124 2125 If unsure, say Y. 2126 2127# Relocation on x86 needs some additional build support 2128config X86_NEED_RELOCS 2129 def_bool y 2130 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2131 select ARCH_VMLINUX_NEEDS_RELOCS 2132 2133config PHYSICAL_ALIGN 2134 hex "Alignment value to which kernel should be aligned" 2135 default "0x200000" 2136 range 0x2000 0x1000000 if X86_32 2137 range 0x200000 0x1000000 if X86_64 2138 help 2139 This value puts the alignment restrictions on physical address 2140 where kernel is loaded and run from. Kernel is compiled for an 2141 address which meets above alignment restriction. 2142 2143 If bootloader loads the kernel at a non-aligned address and 2144 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2145 address aligned to above value and run from there. 2146 2147 If bootloader loads the kernel at a non-aligned address and 2148 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2149 load address and decompress itself to the address it has been 2150 compiled for and run from there. The address for which kernel is 2151 compiled already meets above alignment restrictions. Hence the 2152 end result is that kernel runs from a physical address meeting 2153 above alignment restrictions. 2154 2155 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2156 this value must be a multiple of 0x200000. 2157 2158 Don't change this unless you know what you are doing. 2159 2160config RANDOMIZE_MEMORY 2161 bool "Randomize the kernel memory sections" 2162 depends on X86_64 2163 depends on RANDOMIZE_BASE 2164 default RANDOMIZE_BASE 2165 help 2166 Randomizes the base virtual address of kernel memory sections 2167 (physical memory mapping, vmalloc & vmemmap). This security feature 2168 makes exploits relying on predictable memory locations less reliable. 2169 2170 The order of allocations remains unchanged. Entropy is generated in 2171 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2172 configuration have in average 30,000 different possible virtual 2173 addresses for each memory section. 2174 2175 If unsure, say Y. 2176 2177config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2178 hex "Physical memory mapping padding" if EXPERT 2179 depends on RANDOMIZE_MEMORY 2180 default "0xa" if MEMORY_HOTPLUG 2181 default "0x0" 2182 range 0x1 0x40 if MEMORY_HOTPLUG 2183 range 0x0 0x40 2184 help 2185 Define the padding in terabytes added to the existing physical 2186 memory size during kernel memory randomization. It is useful 2187 for memory hotplug support but reduces the entropy available for 2188 address randomization. 2189 2190 If unsure, leave at the default value. 2191 2192config ADDRESS_MASKING 2193 bool "Linear Address Masking support" 2194 depends on X86_64 2195 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2196 help 2197 Linear Address Masking (LAM) modifies the checking that is applied 2198 to 64-bit linear addresses, allowing software to use of the 2199 untranslated address bits for metadata. 2200 2201 The capability can be used for efficient address sanitizers (ASAN) 2202 implementation and for optimizations in JITs. 2203 2204config HOTPLUG_CPU 2205 def_bool y 2206 depends on SMP 2207 2208config COMPAT_VDSO 2209 def_bool n 2210 prompt "Workaround for glibc 2.3.2 / 2.3.3 (released in year 2003/2004)" 2211 depends on COMPAT_32 2212 help 2213 Certain buggy versions of glibc will crash if they are 2214 presented with a 32-bit vDSO that is not mapped at the address 2215 indicated in its segment table. 2216 2217 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2218 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2219 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2220 the only released version with the bug, but OpenSUSE 9 2221 contains a buggy "glibc 2.3.2". 2222 2223 The symptom of the bug is that everything crashes on startup, saying: 2224 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2225 2226 Saying Y here changes the default value of the vdso32 boot 2227 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2228 This works around the glibc bug but hurts performance. 2229 2230 If unsure, say N: if you are compiling your own kernel, you 2231 are unlikely to be using a buggy version of glibc. 2232 2233choice 2234 prompt "vsyscall table for legacy applications" 2235 depends on X86_64 2236 default LEGACY_VSYSCALL_XONLY 2237 help 2238 Legacy user code that does not know how to find the vDSO expects 2239 to be able to issue three syscalls by calling fixed addresses in 2240 kernel space. Since this location is not randomized with ASLR, 2241 it can be used to assist security vulnerability exploitation. 2242 2243 This setting can be changed at boot time via the kernel command 2244 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2245 is deprecated and can only be enabled using the kernel command 2246 line. 2247 2248 On a system with recent enough glibc (2.14 or newer) and no 2249 static binaries, you can say None without a performance penalty 2250 to improve security. 2251 2252 If unsure, select "Emulate execution only". 2253 2254 config LEGACY_VSYSCALL_XONLY 2255 bool "Emulate execution only" 2256 help 2257 The kernel traps and emulates calls into the fixed vsyscall 2258 address mapping and does not allow reads. This 2259 configuration is recommended when userspace might use the 2260 legacy vsyscall area but support for legacy binary 2261 instrumentation of legacy code is not needed. It mitigates 2262 certain uses of the vsyscall area as an ASLR-bypassing 2263 buffer. 2264 2265 config LEGACY_VSYSCALL_NONE 2266 bool "None" 2267 help 2268 There will be no vsyscall mapping at all. This will 2269 eliminate any risk of ASLR bypass due to the vsyscall 2270 fixed address mapping. Attempts to use the vsyscalls 2271 will be reported to dmesg, so that either old or 2272 malicious userspace programs can be identified. 2273 2274endchoice 2275 2276config CMDLINE_BOOL 2277 bool "Built-in kernel command line" 2278 help 2279 Allow for specifying boot arguments to the kernel at 2280 build time. On some systems (e.g. embedded ones), it is 2281 necessary or convenient to provide some or all of the 2282 kernel boot arguments with the kernel itself (that is, 2283 to not rely on the boot loader to provide them.) 2284 2285 To compile command line arguments into the kernel, 2286 set this option to 'Y', then fill in the 2287 boot arguments in CONFIG_CMDLINE. 2288 2289 Systems with fully functional boot loaders (i.e. non-embedded) 2290 should leave this option set to 'N'. 2291 2292config CMDLINE 2293 string "Built-in kernel command string" 2294 depends on CMDLINE_BOOL 2295 default "" 2296 help 2297 Enter arguments here that should be compiled into the kernel 2298 image and used at boot time. If the boot loader provides a 2299 command line at boot time, it is appended to this string to 2300 form the full kernel command line, when the system boots. 2301 2302 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2303 change this behavior. 2304 2305 In most cases, the command line (whether built-in or provided 2306 by the boot loader) should specify the device for the root 2307 file system. 2308 2309config CMDLINE_OVERRIDE 2310 bool "Built-in command line overrides boot loader arguments" 2311 depends on CMDLINE_BOOL && CMDLINE != "" 2312 help 2313 Set this option to 'Y' to have the kernel ignore the boot loader 2314 command line, and use ONLY the built-in command line. 2315 2316 This is used to work around broken boot loaders. This should 2317 be set to 'N' under normal conditions. 2318 2319config MODIFY_LDT_SYSCALL 2320 bool "Enable the LDT (local descriptor table)" if EXPERT 2321 default y 2322 help 2323 Linux can allow user programs to install a per-process x86 2324 Local Descriptor Table (LDT) using the modify_ldt(2) system 2325 call. This is required to run 16-bit or segmented code such as 2326 DOSEMU or some Wine programs. It is also used by some very old 2327 threading libraries. 2328 2329 Enabling this feature adds a small amount of overhead to 2330 context switches and increases the low-level kernel attack 2331 surface. Disabling it removes the modify_ldt(2) system call. 2332 2333 Saying 'N' here may make sense for embedded or server kernels. 2334 2335config STRICT_SIGALTSTACK_SIZE 2336 bool "Enforce strict size checking for sigaltstack" 2337 depends on DYNAMIC_SIGFRAME 2338 help 2339 For historical reasons MINSIGSTKSZ is a constant which became 2340 already too small with AVX512 support. Add a mechanism to 2341 enforce strict checking of the sigaltstack size against the 2342 real size of the FPU frame. This option enables the check 2343 by default. It can also be controlled via the kernel command 2344 line option 'strict_sas_size' independent of this config 2345 switch. Enabling it might break existing applications which 2346 allocate a too small sigaltstack but 'work' because they 2347 never get a signal delivered. 2348 2349 Say 'N' unless you want to really enforce this check. 2350 2351config CFI_AUTO_DEFAULT 2352 bool "Attempt to use FineIBT by default at boot time" 2353 depends on FINEIBT 2354 depends on !RUST || RUSTC_VERSION >= 108800 2355 default y 2356 help 2357 Attempt to use FineIBT by default at boot time. If enabled, 2358 this is the same as booting with "cfi=auto". If disabled, 2359 this is the same as booting with "cfi=kcfi". 2360 2361source "kernel/livepatch/Kconfig" 2362 2363config X86_BUS_LOCK_DETECT 2364 bool "Split Lock Detect and Bus Lock Detect support" 2365 depends on CPU_SUP_INTEL || CPU_SUP_AMD 2366 default y 2367 help 2368 Enable Split Lock Detect and Bus Lock Detect functionalities. 2369 See <file:Documentation/arch/x86/buslock.rst> for more information. 2370 2371endmenu 2372 2373config CC_HAS_NAMED_AS 2374 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null) 2375 depends on CC_IS_GCC 2376 2377# 2378# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN) 2379# are incompatible with named address spaces with GCC < 13.3 2380# (see GCC PR sanitizer/111736 and also PR sanitizer/115172). 2381# 2382 2383config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2384 def_bool y 2385 depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300 2386 depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200 2387 2388config USE_X86_SEG_SUPPORT 2389 def_bool CC_HAS_NAMED_AS 2390 depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS 2391 2392config CC_HAS_SLS 2393 def_bool $(cc-option,-mharden-sls=all) 2394 2395config CC_HAS_RETURN_THUNK 2396 def_bool $(cc-option,-mfunction-return=thunk-extern) 2397 2398config CC_HAS_ENTRY_PADDING 2399 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2400 2401config CC_HAS_KCFI_ARITY 2402 def_bool $(cc-option,-fsanitize=kcfi -fsanitize-kcfi-arity) 2403 depends on CC_IS_CLANG && !RUST 2404 2405config FUNCTION_PADDING_CFI 2406 int 2407 default 59 if FUNCTION_ALIGNMENT_64B 2408 default 27 if FUNCTION_ALIGNMENT_32B 2409 default 11 if FUNCTION_ALIGNMENT_16B 2410 default 3 if FUNCTION_ALIGNMENT_8B 2411 default 0 2412 2413# Basically: FUNCTION_ALIGNMENT - 5*CFI 2414# except Kconfig can't do arithmetic :/ 2415config FUNCTION_PADDING_BYTES 2416 int 2417 default FUNCTION_PADDING_CFI if CFI 2418 default FUNCTION_ALIGNMENT 2419 2420config CALL_PADDING 2421 def_bool n 2422 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2423 select FUNCTION_ALIGNMENT_16B 2424 2425config FINEIBT 2426 def_bool y 2427 depends on X86_KERNEL_IBT && CFI && MITIGATION_RETPOLINE 2428 select CALL_PADDING 2429 2430config FINEIBT_BHI 2431 def_bool y 2432 depends on FINEIBT && CC_HAS_KCFI_ARITY 2433 2434config HAVE_CALL_THUNKS 2435 def_bool y 2436 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2437 2438config CALL_THUNKS 2439 def_bool n 2440 select CALL_PADDING 2441 2442config PREFIX_SYMBOLS 2443 def_bool y 2444 depends on CALL_PADDING && !CFI 2445 2446menuconfig CPU_MITIGATIONS 2447 bool "Mitigations for CPU vulnerabilities" 2448 default y 2449 help 2450 Say Y here to enable options which enable mitigations for hardware 2451 vulnerabilities (usually related to speculative execution). 2452 Mitigations can be disabled or restricted to SMT systems at runtime 2453 via the "mitigations" kernel parameter. 2454 2455 If you say N, all mitigations will be disabled. This CANNOT be 2456 overridden at runtime. 2457 2458 Say 'Y', unless you really know what you are doing. 2459 2460if CPU_MITIGATIONS 2461 2462config MITIGATION_PAGE_TABLE_ISOLATION 2463 bool "Remove the kernel mapping in user mode" 2464 default y 2465 depends on (X86_64 || X86_PAE) 2466 help 2467 This feature reduces the number of hardware side channels by 2468 ensuring that the majority of kernel addresses are not mapped 2469 into userspace. 2470 2471 See Documentation/arch/x86/pti.rst for more details. 2472 2473config MITIGATION_RETPOLINE 2474 bool "Avoid speculative indirect branches in kernel" 2475 select OBJTOOL if HAVE_OBJTOOL 2476 default y 2477 help 2478 Compile kernel with the retpoline compiler options to guard against 2479 kernel-to-user data leaks by avoiding speculative indirect 2480 branches. Requires a compiler with -mindirect-branch=thunk-extern 2481 support for full protection. The kernel may run slower. 2482 2483config MITIGATION_RETHUNK 2484 bool "Enable return-thunks" 2485 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2486 select OBJTOOL if HAVE_OBJTOOL 2487 default y if X86_64 2488 help 2489 Compile the kernel with the return-thunks compiler option to guard 2490 against kernel-to-user data leaks by avoiding return speculation. 2491 Requires a compiler with -mfunction-return=thunk-extern 2492 support for full protection. The kernel may run slower. 2493 2494config MITIGATION_UNRET_ENTRY 2495 bool "Enable UNRET on kernel entry" 2496 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2497 default y 2498 help 2499 Compile the kernel with support for the retbleed=unret mitigation. 2500 2501config MITIGATION_CALL_DEPTH_TRACKING 2502 bool "Mitigate RSB underflow with call depth tracking" 2503 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2504 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2505 select CALL_THUNKS 2506 default y 2507 help 2508 Compile the kernel with call depth tracking to mitigate the Intel 2509 SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off 2510 by default and needs to be enabled on the kernel command line via the 2511 retbleed=stuff option. For non-affected systems the overhead of this 2512 option is marginal as the call depth tracking is using run-time 2513 generated call thunks in a compiler generated padding area and call 2514 patching. This increases text size by ~5%. For non affected systems 2515 this space is unused. On affected SKL systems this results in a 2516 significant performance gain over the IBRS mitigation. 2517 2518config CALL_THUNKS_DEBUG 2519 bool "Enable call thunks and call depth tracking debugging" 2520 depends on MITIGATION_CALL_DEPTH_TRACKING 2521 select FUNCTION_ALIGNMENT_32B 2522 default n 2523 help 2524 Enable call/ret counters for imbalance detection and build in 2525 a noisy dmesg about callthunks generation and call patching for 2526 trouble shooting. The debug prints need to be enabled on the 2527 kernel command line with 'debug-callthunks'. 2528 Only enable this when you are debugging call thunks as this 2529 creates a noticeable runtime overhead. If unsure say N. 2530 2531config MITIGATION_IBPB_ENTRY 2532 bool "Enable IBPB on kernel entry" 2533 depends on CPU_SUP_AMD && X86_64 2534 default y 2535 help 2536 Compile the kernel with support for the retbleed=ibpb and 2537 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations. 2538 2539config MITIGATION_IBRS_ENTRY 2540 bool "Enable IBRS on kernel entry" 2541 depends on CPU_SUP_INTEL && X86_64 2542 default y 2543 help 2544 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2545 This mitigates both spectre_v2 and retbleed at great cost to 2546 performance. 2547 2548config MITIGATION_SRSO 2549 bool "Mitigate speculative RAS overflow on AMD" 2550 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2551 default y 2552 help 2553 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2554 2555config MITIGATION_SLS 2556 bool "Mitigate Straight-Line-Speculation" 2557 depends on CC_HAS_SLS && X86_64 2558 select OBJTOOL if HAVE_OBJTOOL 2559 default n 2560 help 2561 Compile the kernel with straight-line-speculation options to guard 2562 against straight line speculation. The kernel image might be slightly 2563 larger. 2564 2565config MITIGATION_GDS 2566 bool "Mitigate Gather Data Sampling" 2567 depends on CPU_SUP_INTEL 2568 default y 2569 help 2570 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware 2571 vulnerability which allows unprivileged speculative access to data 2572 which was previously stored in vector registers. The attacker uses gather 2573 instructions to infer the stale vector register data. 2574 2575config MITIGATION_RFDS 2576 bool "RFDS Mitigation" 2577 depends on CPU_SUP_INTEL 2578 default y 2579 help 2580 Enable mitigation for Register File Data Sampling (RFDS) by default. 2581 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2582 allows unprivileged speculative access to stale data previously 2583 stored in floating point, vector and integer registers. 2584 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2585 2586config MITIGATION_SPECTRE_BHI 2587 bool "Mitigate Spectre-BHB (Branch History Injection)" 2588 depends on CPU_SUP_INTEL 2589 default y 2590 help 2591 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2592 where the branch history buffer is poisoned to speculatively steer 2593 indirect branches. 2594 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2595 2596config MITIGATION_MDS 2597 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug" 2598 depends on CPU_SUP_INTEL 2599 default y 2600 help 2601 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is 2602 a hardware vulnerability which allows unprivileged speculative access 2603 to data which is available in various CPU internal buffers. 2604 See also <file:Documentation/admin-guide/hw-vuln/mds.rst> 2605 2606config MITIGATION_TAA 2607 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug" 2608 depends on CPU_SUP_INTEL 2609 default y 2610 help 2611 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware 2612 vulnerability that allows unprivileged speculative access to data 2613 which is available in various CPU internal buffers by using 2614 asynchronous aborts within an Intel TSX transactional region. 2615 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst> 2616 2617config MITIGATION_MMIO_STALE_DATA 2618 bool "Mitigate MMIO Stale Data hardware bug" 2619 depends on CPU_SUP_INTEL 2620 default y 2621 help 2622 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO 2623 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO) 2624 vulnerabilities that can expose data. The vulnerabilities require the 2625 attacker to have access to MMIO. 2626 See also 2627 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst> 2628 2629config MITIGATION_L1TF 2630 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug" 2631 depends on CPU_SUP_INTEL 2632 default y 2633 help 2634 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a 2635 hardware vulnerability which allows unprivileged speculative access to data 2636 available in the Level 1 Data Cache. 2637 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst 2638 2639config MITIGATION_RETBLEED 2640 bool "Mitigate RETBleed hardware bug" 2641 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY 2642 default y 2643 help 2644 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution 2645 with Return Instructions) vulnerability. RETBleed is a speculative 2646 execution attack which takes advantage of microarchitectural behavior 2647 in many modern microprocessors, similar to Spectre v2. An 2648 unprivileged attacker can use these flaws to bypass conventional 2649 memory security restrictions to gain read access to privileged memory 2650 that would otherwise be inaccessible. 2651 2652config MITIGATION_SPECTRE_V1 2653 bool "Mitigate SPECTRE V1 hardware bug" 2654 default y 2655 help 2656 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a 2657 class of side channel attacks that takes advantage of speculative 2658 execution that bypasses conditional branch instructions used for 2659 memory access bounds check. 2660 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2661 2662config MITIGATION_SPECTRE_V2 2663 bool "Mitigate SPECTRE V2 hardware bug" 2664 default y 2665 help 2666 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre 2667 V2 is a class of side channel attacks that takes advantage of 2668 indirect branch predictors inside the processor. In Spectre variant 2 2669 attacks, the attacker can steer speculative indirect branches in the 2670 victim to gadget code by poisoning the branch target buffer of a CPU 2671 used for predicting indirect branch addresses. 2672 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2673 2674config MITIGATION_SRBDS 2675 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug" 2676 depends on CPU_SUP_INTEL 2677 default y 2678 help 2679 Enable mitigation for Special Register Buffer Data Sampling (SRBDS). 2680 SRBDS is a hardware vulnerability that allows Microarchitectural Data 2681 Sampling (MDS) techniques to infer values returned from special 2682 register accesses. An unprivileged user can extract values returned 2683 from RDRAND and RDSEED executed on another core or sibling thread 2684 using MDS techniques. 2685 See also 2686 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst> 2687 2688config MITIGATION_SSB 2689 bool "Mitigate Speculative Store Bypass (SSB) hardware bug" 2690 default y 2691 help 2692 Enable mitigation for Speculative Store Bypass (SSB). SSB is a 2693 hardware security vulnerability and its exploitation takes advantage 2694 of speculative execution in a similar way to the Meltdown and Spectre 2695 security vulnerabilities. 2696 2697config MITIGATION_ITS 2698 bool "Enable Indirect Target Selection mitigation" 2699 depends on CPU_SUP_INTEL && X86_64 2700 depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK 2701 select EXECMEM 2702 default y 2703 help 2704 Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in 2705 BPU on some Intel CPUs that may allow Spectre V2 style attacks. If 2706 disabled, mitigation cannot be enabled via cmdline. 2707 See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst> 2708 2709config MITIGATION_TSA 2710 bool "Mitigate Transient Scheduler Attacks" 2711 depends on CPU_SUP_AMD 2712 default y 2713 help 2714 Enable mitigation for Transient Scheduler Attacks. TSA is a hardware 2715 security vulnerability on AMD CPUs which can lead to forwarding of 2716 invalid info to subsequent instructions and thus can affect their 2717 timing and thereby cause a leakage. 2718 2719config MITIGATION_VMSCAPE 2720 bool "Mitigate VMSCAPE" 2721 depends on KVM 2722 default y 2723 help 2724 Enable mitigation for VMSCAPE attacks. VMSCAPE is a hardware security 2725 vulnerability on Intel and AMD CPUs that may allow a guest to do 2726 Spectre v2 style attacks on userspace hypervisor. 2727endif 2728 2729config ARCH_HAS_ADD_PAGES 2730 def_bool y 2731 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2732 2733menu "Power management and ACPI options" 2734 2735config ARCH_HIBERNATION_HEADER 2736 def_bool y 2737 depends on HIBERNATION 2738 2739source "kernel/power/Kconfig" 2740 2741source "drivers/acpi/Kconfig" 2742 2743config X86_APM_BOOT 2744 def_bool y 2745 depends on APM 2746 2747menuconfig APM 2748 tristate "APM (Advanced Power Management) BIOS support" 2749 depends on X86_32 && PM_SLEEP 2750 help 2751 APM is a BIOS specification for saving power using several different 2752 techniques. This is mostly useful for battery powered laptops with 2753 APM compliant BIOSes. If you say Y here, the system time will be 2754 reset after a RESUME operation, the /proc/apm device will provide 2755 battery status information, and user-space programs will receive 2756 notification of APM "events" (e.g. battery status change). 2757 2758 If you select "Y" here, you can disable actual use of the APM 2759 BIOS by passing the "apm=off" option to the kernel at boot time. 2760 2761 Note that the APM support is almost completely disabled for 2762 machines with more than one CPU. 2763 2764 In order to use APM, you will need supporting software. For location 2765 and more information, read <file:Documentation/power/apm-acpi.rst> 2766 and the Battery Powered Linux mini-HOWTO, available from 2767 <http://www.tldp.org/docs.html#howto>. 2768 2769 This driver does not spin down disk drives (see the hdparm(8) 2770 manpage ("man 8 hdparm") for that), and it doesn't turn off 2771 VESA-compliant "green" monitors. 2772 2773 This driver does not support the TI 4000M TravelMate and the ACER 2774 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2775 desktop machines also don't have compliant BIOSes, and this driver 2776 may cause those machines to panic during the boot phase. 2777 2778 Generally, if you don't have a battery in your machine, there isn't 2779 much point in using this driver and you should say N. If you get 2780 random kernel OOPSes or reboots that don't seem to be related to 2781 anything, try disabling/enabling this option (or disabling/enabling 2782 APM in your BIOS). 2783 2784 Some other things you should try when experiencing seemingly random, 2785 "weird" problems: 2786 2787 1) make sure that you have enough swap space and that it is 2788 enabled. 2789 2) pass the "idle=poll" option to the kernel 2790 3) switch on floating point emulation in the kernel and pass 2791 the "no387" option to the kernel 2792 4) pass the "floppy=nodma" option to the kernel 2793 5) pass the "mem=4M" option to the kernel (thereby disabling 2794 all but the first 4 MB of RAM) 2795 6) make sure that the CPU is not over clocked. 2796 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2797 8) disable the cache from your BIOS settings 2798 9) install a fan for the video card or exchange video RAM 2799 10) install a better fan for the CPU 2800 11) exchange RAM chips 2801 12) exchange the motherboard. 2802 2803 To compile this driver as a module, choose M here: the 2804 module will be called apm. 2805 2806if APM 2807 2808config APM_IGNORE_USER_SUSPEND 2809 bool "Ignore USER SUSPEND" 2810 help 2811 This option will ignore USER SUSPEND requests. On machines with a 2812 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2813 series notebooks, it is necessary to say Y because of a BIOS bug. 2814 2815config APM_DO_ENABLE 2816 bool "Enable PM at boot time" 2817 help 2818 Enable APM features at boot time. From page 36 of the APM BIOS 2819 specification: "When disabled, the APM BIOS does not automatically 2820 power manage devices, enter the Standby State, enter the Suspend 2821 State, or take power saving steps in response to CPU Idle calls." 2822 This driver will make CPU Idle calls when Linux is idle (unless this 2823 feature is turned off -- see "Do CPU IDLE calls", below). This 2824 should always save battery power, but more complicated APM features 2825 will be dependent on your BIOS implementation. You may need to turn 2826 this option off if your computer hangs at boot time when using APM 2827 support, or if it beeps continuously instead of suspending. Turn 2828 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2829 T400CDT. This is off by default since most machines do fine without 2830 this feature. 2831 2832config APM_CPU_IDLE 2833 depends on CPU_IDLE 2834 bool "Make CPU Idle calls when idle" 2835 help 2836 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2837 On some machines, this can activate improved power savings, such as 2838 a slowed CPU clock rate, when the machine is idle. These idle calls 2839 are made after the idle loop has run for some length of time (e.g., 2840 333 mS). On some machines, this will cause a hang at boot time or 2841 whenever the CPU becomes idle. (On machines with more than one CPU, 2842 this option does nothing.) 2843 2844config APM_DISPLAY_BLANK 2845 bool "Enable console blanking using APM" 2846 help 2847 Enable console blanking using the APM. Some laptops can use this to 2848 turn off the LCD backlight when the screen blanker of the Linux 2849 virtual console blanks the screen. Note that this is only used by 2850 the virtual console screen blanker, and won't turn off the backlight 2851 when using the X Window system. This also doesn't have anything to 2852 do with your VESA-compliant power-saving monitor. Further, this 2853 option doesn't work for all laptops -- it might not turn off your 2854 backlight at all, or it might print a lot of errors to the console, 2855 especially if you are using gpm. 2856 2857config APM_ALLOW_INTS 2858 bool "Allow interrupts during APM BIOS calls" 2859 help 2860 Normally we disable external interrupts while we are making calls to 2861 the APM BIOS as a measure to lessen the effects of a badly behaving 2862 BIOS implementation. The BIOS should reenable interrupts if it 2863 needs to. Unfortunately, some BIOSes do not -- especially those in 2864 many of the newer IBM Thinkpads. If you experience hangs when you 2865 suspend, try setting this to Y. Otherwise, say N. 2866 2867endif # APM 2868 2869source "drivers/cpufreq/Kconfig" 2870 2871source "drivers/cpuidle/Kconfig" 2872 2873source "drivers/idle/Kconfig" 2874 2875endmenu 2876 2877menu "Bus options (PCI etc.)" 2878 2879choice 2880 prompt "PCI access mode" 2881 depends on X86_32 && PCI 2882 default PCI_GOANY 2883 help 2884 On PCI systems, the BIOS can be used to detect the PCI devices and 2885 determine their configuration. However, some old PCI motherboards 2886 have BIOS bugs and may crash if this is done. Also, some embedded 2887 PCI-based systems don't have any BIOS at all. Linux can also try to 2888 detect the PCI hardware directly without using the BIOS. 2889 2890 With this option, you can specify how Linux should detect the 2891 PCI devices. If you choose "BIOS", the BIOS will be used, 2892 if you choose "Direct", the BIOS won't be used, and if you 2893 choose "MMConfig", then PCI Express MMCONFIG will be used. 2894 If you choose "Any", the kernel will try MMCONFIG, then the 2895 direct access method and falls back to the BIOS if that doesn't 2896 work. If unsure, go with the default, which is "Any". 2897 2898config PCI_GOBIOS 2899 bool "BIOS" 2900 2901config PCI_GOMMCONFIG 2902 bool "MMConfig" 2903 2904config PCI_GODIRECT 2905 bool "Direct" 2906 2907config PCI_GOOLPC 2908 bool "OLPC XO-1" 2909 depends on OLPC 2910 2911config PCI_GOANY 2912 bool "Any" 2913 2914endchoice 2915 2916config PCI_BIOS 2917 def_bool y 2918 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2919 2920# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2921config PCI_DIRECT 2922 def_bool y 2923 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2924 2925config PCI_MMCONFIG 2926 bool "Support mmconfig PCI config space access" if X86_64 2927 default y 2928 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2929 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2930 help 2931 Add support for accessing the PCI configuration space as a memory 2932 mapped area. It is the recommended method if the system supports 2933 this (it must have PCI Express and ACPI for it to be available). 2934 2935 In the unlikely case that enabling this configuration option causes 2936 problems, the mechanism can be switched off with the 'pci=nommconf' 2937 command line parameter. 2938 2939 Say N only if you are sure that your platform does not support this 2940 access method or you have problems caused by it. 2941 2942 Say Y otherwise. 2943 2944config PCI_OLPC 2945 def_bool y 2946 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2947 2948config PCI_XEN 2949 def_bool y 2950 depends on PCI && XEN 2951 2952config MMCONF_FAM10H 2953 def_bool y 2954 depends on X86_64 && PCI_MMCONFIG && ACPI 2955 2956config PCI_CNB20LE_QUIRK 2957 bool "Read PCI host bridge windows from the CNB20LE chipset" if EXPERT 2958 depends on X86_32 && PCI 2959 help 2960 Read the PCI windows out of the CNB20LE host bridge. This allows 2961 PCI hotplug to work on systems with the CNB20LE chipset which do 2962 not have ACPI. 2963 2964 The ServerWorks (later Broadcom) CNB20LE was a chipset designed 2965 most probably only for Pentium III. 2966 2967 To find out if you have such a chipset, search for a PCI device with 2968 1166:0009 PCI IDs, for example by executing 2969 lspci -nn | grep '1166:0009' 2970 The code is inactive if there is none. 2971 2972 There's no public spec for this chipset, and this functionality 2973 is known to be incomplete. 2974 2975 You should say N unless you know you need this. 2976 2977config ISA_BUS 2978 bool "ISA bus support on modern systems" if EXPERT 2979 help 2980 Expose ISA bus device drivers and options available for selection and 2981 configuration. Enable this option if your target machine has an ISA 2982 bus. ISA is an older system, displaced by PCI and newer bus 2983 architectures -- if your target machine is modern, it probably does 2984 not have an ISA bus. 2985 2986 If unsure, say N. 2987 2988# x86_64 have no ISA slots, but can have ISA-style DMA. 2989config ISA_DMA_API 2990 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2991 default y 2992 help 2993 Enables ISA-style DMA support for devices requiring such controllers. 2994 If unsure, say Y. 2995 2996if X86_32 2997 2998config ISA 2999 bool "ISA support" 3000 help 3001 Find out whether you have ISA slots on your motherboard. ISA is the 3002 name of a bus system, i.e. the way the CPU talks to the other stuff 3003 inside your box. Other bus systems are PCI, EISA, MicroChannel 3004 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 3005 newer boards don't support it. If you have ISA, say Y, otherwise N. 3006 3007config SCx200 3008 tristate "NatSemi SCx200 support" 3009 help 3010 This provides basic support for National Semiconductor's 3011 (now AMD's) Geode processors. The driver probes for the 3012 PCI-IDs of several on-chip devices, so its a good dependency 3013 for other scx200_* drivers. 3014 3015 If compiled as a module, the driver is named scx200. 3016 3017config SCx200HR_TIMER 3018 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 3019 depends on SCx200 3020 default y 3021 help 3022 This driver provides a clocksource built upon the on-chip 3023 27MHz high-resolution timer. Its also a workaround for 3024 NSC Geode SC-1100's buggy TSC, which loses time when the 3025 processor goes idle (as is done by the scheduler). The 3026 other workaround is idle=poll boot option. 3027 3028config OLPC 3029 bool "One Laptop Per Child support" 3030 depends on !X86_PAE 3031 select GPIOLIB 3032 select OF 3033 select OF_PROMTREE 3034 select IRQ_DOMAIN 3035 select OLPC_EC 3036 help 3037 Add support for detecting the unique features of the OLPC 3038 XO hardware. 3039 3040config OLPC_XO1_PM 3041 bool "OLPC XO-1 Power Management" 3042 depends on OLPC && MFD_CS5535=y && PM_SLEEP 3043 help 3044 Add support for poweroff and suspend of the OLPC XO-1 laptop. 3045 3046config OLPC_XO1_RTC 3047 bool "OLPC XO-1 Real Time Clock" 3048 depends on OLPC_XO1_PM && RTC_DRV_CMOS 3049 help 3050 Add support for the XO-1 real time clock, which can be used as a 3051 programmable wakeup source. 3052 3053config OLPC_XO1_SCI 3054 bool "OLPC XO-1 SCI extras" 3055 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 3056 depends on INPUT=y 3057 select POWER_SUPPLY 3058 help 3059 Add support for SCI-based features of the OLPC XO-1 laptop: 3060 - EC-driven system wakeups 3061 - Power button 3062 - Ebook switch 3063 - Lid switch 3064 - AC adapter status updates 3065 - Battery status updates 3066 3067config OLPC_XO15_SCI 3068 bool "OLPC XO-1.5 SCI extras" 3069 depends on OLPC && ACPI 3070 select POWER_SUPPLY 3071 help 3072 Add support for SCI-based features of the OLPC XO-1.5 laptop: 3073 - EC-driven system wakeups 3074 - AC adapter status updates 3075 - Battery status updates 3076 3077config GEODE_COMMON 3078 bool 3079 3080config ALIX 3081 bool "PCEngines ALIX System Support (LED setup)" 3082 select GPIOLIB 3083 select GEODE_COMMON 3084 help 3085 This option enables system support for the PCEngines ALIX. 3086 At present this just sets up LEDs for GPIO control on 3087 ALIX2/3/6 boards. However, other system specific setup should 3088 get added here. 3089 3090 Note: You must still enable the drivers for GPIO and LED support 3091 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 3092 3093 Note: You have to set alix.force=1 for boards with Award BIOS. 3094 3095config NET5501 3096 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3097 select GPIOLIB 3098 select GEODE_COMMON 3099 help 3100 This option enables system support for the Soekris Engineering net5501. 3101 3102config GEOS 3103 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3104 select GPIOLIB 3105 select GEODE_COMMON 3106 depends on DMI 3107 help 3108 This option enables system support for the Traverse Technologies GEOS. 3109 3110config TS5500 3111 bool "Technologic Systems TS-5500 platform support" 3112 depends on MELAN 3113 select CHECK_SIGNATURE 3114 select NEW_LEDS 3115 select LEDS_CLASS 3116 help 3117 This option enables system support for the Technologic Systems TS-5500. 3118 3119endif # X86_32 3120 3121config AMD_NB 3122 def_bool y 3123 depends on AMD_NODE 3124 3125config AMD_NODE 3126 def_bool y 3127 depends on CPU_SUP_AMD && PCI 3128 3129endmenu 3130 3131menu "Binary Emulations" 3132 3133config IA32_EMULATION 3134 bool "IA32 Emulation" 3135 depends on X86_64 3136 select ARCH_WANT_OLD_COMPAT_IPC 3137 select BINFMT_ELF 3138 select COMPAT_OLD_SIGACTION 3139 help 3140 Include code to run legacy 32-bit programs under a 3141 64-bit kernel. You should likely turn this on, unless you're 3142 100% sure that you don't have any 32-bit programs left. 3143 3144config IA32_EMULATION_DEFAULT_DISABLED 3145 bool "IA32 emulation disabled by default" 3146 default n 3147 depends on IA32_EMULATION 3148 help 3149 Make IA32 emulation disabled by default. This prevents loading 32-bit 3150 processes and access to 32-bit syscalls. If unsure, leave it to its 3151 default value. 3152 3153config X86_X32_ABI 3154 bool "x32 ABI for 64-bit mode" 3155 depends on X86_64 3156 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3157 # compressed debug sections to x86_x32 properly: 3158 # https://github.com/ClangBuiltLinux/linux/issues/514 3159 # https://github.com/ClangBuiltLinux/linux/issues/1141 3160 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3161 help 3162 Include code to run binaries for the x32 native 32-bit ABI 3163 for 64-bit processors. An x32 process gets access to the 3164 full 64-bit register file and wide data path while leaving 3165 pointers at 32 bits for smaller memory footprint. 3166 3167config COMPAT_32 3168 def_bool y 3169 depends on IA32_EMULATION || X86_32 3170 select HAVE_UID16 3171 select OLD_SIGSUSPEND3 3172 3173config COMPAT 3174 def_bool y 3175 depends on IA32_EMULATION || X86_X32_ABI 3176 3177config COMPAT_FOR_U64_ALIGNMENT 3178 def_bool y 3179 depends on COMPAT 3180 3181endmenu 3182 3183config HAVE_ATOMIC_IOMAP 3184 def_bool y 3185 depends on X86_32 3186 3187source "arch/x86/kvm/Kconfig" 3188 3189source "arch/x86/Kconfig.cpufeatures" 3190 3191source "arch/x86/Kconfig.assembler" 3192