1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select HAVE_DEBUG_STACKOVERFLOW 18 select KMAP_LOCAL 19 select MODULES_USE_ELF_REL 20 select OLD_SIGACTION 21 select ARCH_SPLIT_ARG64 22 23config X86_64 24 def_bool y 25 depends on 64BIT 26 # Options that are inherently 64-bit kernel only: 27 select ARCH_HAS_GIGANTIC_PAGE 28 select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE 32 select HAVE_ARCH_SOFT_DIRTY 33 select MODULES_USE_ELF_RELA 34 select NEED_DMA_MAP_STATE 35 select SWIOTLB 36 select ARCH_HAS_ELFCORE_COMPAT 37 select ZONE_DMA32 38 select EXECMEM if DYNAMIC_FTRACE 39 select ACPI_MRRM if ACPI 40 41config FORCE_DYNAMIC_FTRACE 42 def_bool y 43 depends on X86_32 44 depends on FUNCTION_TRACER 45 select DYNAMIC_FTRACE 46 help 47 We keep the static function tracing (!DYNAMIC_FTRACE) around 48 in order to test the non static function tracing in the 49 generic code, as other architectures still use it. But we 50 only need to keep it around for x86_64. No need to keep it 51 for x86_32. For x86_32, force DYNAMIC_FTRACE. 52# 53# Arch settings 54# 55# ( Note that options that are marked 'if X86_64' could in principle be 56# ported to 32-bit as well. ) 57# 58config X86 59 def_bool y 60 # 61 # Note: keep this list sorted alphabetically 62 # 63 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 64 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 65 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 66 select ARCH_32BIT_OFF_T if X86_32 67 select ARCH_CLOCKSOURCE_INIT 68 select ARCH_CONFIGURES_CPU_MITIGATIONS 69 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 70 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 71 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 72 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 73 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 74 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 75 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 76 select ARCH_HAS_CPU_ATTACK_VECTORS if CPU_MITIGATIONS 77 select ARCH_HAS_CACHE_LINE_SIZE 78 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 79 select ARCH_HAS_CPU_FINALIZE_INIT 80 select ARCH_HAS_CPU_PASID if IOMMU_SVA 81 select ARCH_HAS_CURRENT_STACK_POINTER 82 select ARCH_HAS_DEBUG_VIRTUAL 83 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 84 select ARCH_HAS_DEVMEM_IS_ALLOWED 85 select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN 86 select ARCH_HAS_EARLY_DEBUG if KGDB 87 select ARCH_HAS_ELF_RANDOMIZE 88 select ARCH_HAS_EXECMEM_ROX if X86_64 && STRICT_MODULE_RWX 89 select ARCH_HAS_FAST_MULTIPLIER 90 select ARCH_HAS_FORTIFY_SOURCE 91 select ARCH_HAS_GCOV_PROFILE_ALL 92 select ARCH_HAS_KCOV if X86_64 93 select ARCH_HAS_KERNEL_FPU_SUPPORT 94 select ARCH_HAS_MEM_ENCRYPT 95 select ARCH_HAS_MEMBARRIER_SYNC_CORE 96 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 97 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 98 select ARCH_HAS_PMEM_API if X86_64 99 select ARCH_HAS_PREEMPT_LAZY 100 select ARCH_HAS_PTDUMP 101 select ARCH_HAS_PTE_SPECIAL 102 select ARCH_HAS_HW_PTE_YOUNG 103 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 104 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 105 select ARCH_HAS_COPY_MC if X86_64 106 select ARCH_HAS_SET_MEMORY 107 select ARCH_HAS_SET_DIRECT_MAP 108 select ARCH_HAS_STRICT_KERNEL_RWX 109 select ARCH_HAS_STRICT_MODULE_RWX 110 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 111 select ARCH_HAS_SYSCALL_WRAPPER 112 select ARCH_HAS_UBSAN 113 select ARCH_HAS_DEBUG_WX 114 select ARCH_HAS_ZONE_DMA_SET if EXPERT 115 select ARCH_HAVE_NMI_SAFE_CMPXCHG 116 select ARCH_HAVE_EXTRA_ELF_NOTES 117 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 118 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 119 select ARCH_MIGHT_HAVE_PC_PARPORT 120 select ARCH_MIGHT_HAVE_PC_SERIO 121 select ARCH_STACKWALK 122 select ARCH_SUPPORTS_ACPI 123 select ARCH_SUPPORTS_ATOMIC_RMW 124 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 125 select ARCH_SUPPORTS_HUGETLBFS 126 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 127 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 128 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 129 select ARCH_SUPPORTS_CFI if X86_64 130 select ARCH_USES_CFI_TRAPS if X86_64 && CFI 131 select ARCH_SUPPORTS_LTO_CLANG 132 select ARCH_SUPPORTS_LTO_CLANG_THIN 133 select ARCH_SUPPORTS_RT 134 select ARCH_SUPPORTS_AUTOFDO_CLANG 135 select ARCH_SUPPORTS_PROPELLER_CLANG if X86_64 136 select ARCH_USE_BUILTIN_BSWAP 137 select ARCH_USE_CMPXCHG_LOCKREF if X86_CX8 138 select ARCH_USE_MEMTEST 139 select ARCH_USE_QUEUED_RWLOCKS 140 select ARCH_USE_QUEUED_SPINLOCKS 141 select ARCH_USE_SYM_ANNOTATIONS 142 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 143 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 144 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 145 select ARCH_WANTS_NO_INSTR 146 select ARCH_WANT_GENERAL_HUGETLB 147 select ARCH_WANT_HUGE_PMD_SHARE if X86_64 148 select ARCH_WANT_LD_ORPHAN_WARN 149 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 150 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 151 select ARCH_WANT_HUGETLB_VMEMMAP_PREINIT if X86_64 152 select ARCH_WANTS_THP_SWAP if X86_64 153 select ARCH_HAS_PARANOID_L1D_FLUSH 154 select ARCH_WANT_IRQS_OFF_ACTIVATE_MM 155 select BUILDTIME_TABLE_SORT 156 select CLKEVT_I8253 157 select CLOCKSOURCE_WATCHDOG 158 # Word-size accesses may read uninitialized data past the trailing \0 159 # in strings and cause false KMSAN reports. 160 select DCACHE_WORD_ACCESS if !KMSAN 161 select DYNAMIC_SIGFRAME 162 select EDAC_ATOMIC_SCRUB 163 select EDAC_SUPPORT 164 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 165 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 166 select GENERIC_CLOCKEVENTS_MIN_ADJUST 167 select GENERIC_CMOS_UPDATE 168 select GENERIC_CPU_AUTOPROBE 169 select GENERIC_CPU_DEVICES 170 select GENERIC_CPU_VULNERABILITIES 171 select GENERIC_EARLY_IOREMAP 172 select GENERIC_ENTRY 173 select GENERIC_IOMAP 174 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 175 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 176 select GENERIC_IRQ_MIGRATION if SMP 177 select GENERIC_IRQ_PROBE 178 select GENERIC_IRQ_RESERVATION_MODE 179 select GENERIC_IRQ_SHOW 180 select GENERIC_PENDING_IRQ if SMP 181 select GENERIC_SMP_IDLE_THREAD 182 select GENERIC_TIME_VSYSCALL 183 select GENERIC_GETTIMEOFDAY 184 select GENERIC_VDSO_OVERFLOW_PROTECT 185 select GUP_GET_PXX_LOW_HIGH if X86_PAE 186 select HARDIRQS_SW_RESEND 187 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 188 select HAS_IOPORT 189 select HAVE_ACPI_APEI if ACPI 190 select HAVE_ACPI_APEI_NMI if ACPI 191 select HAVE_ALIGNED_STRUCT_PAGE 192 select HAVE_ARCH_AUDITSYSCALL 193 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 194 select HAVE_ARCH_HUGE_VMALLOC if X86_64 195 select HAVE_ARCH_JUMP_LABEL 196 select HAVE_ARCH_JUMP_LABEL_RELATIVE 197 select HAVE_ARCH_KASAN if X86_64 198 select HAVE_ARCH_KASAN_VMALLOC if X86_64 199 select HAVE_ARCH_KFENCE 200 select HAVE_ARCH_KMSAN if X86_64 201 select HAVE_ARCH_KGDB 202 select HAVE_ARCH_KSTACK_ERASE 203 select HAVE_ARCH_MMAP_RND_BITS if MMU 204 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 205 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 206 select HAVE_ARCH_PREL32_RELOCATIONS 207 select HAVE_ARCH_SECCOMP_FILTER 208 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 209 select HAVE_ARCH_TRACEHOOK 210 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 211 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 212 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 213 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 214 select HAVE_ARCH_VMAP_STACK if X86_64 215 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 216 select HAVE_ARCH_WITHIN_STACK_FRAMES 217 select HAVE_ASM_MODVERSIONS 218 select HAVE_CMPXCHG_DOUBLE 219 select HAVE_CMPXCHG_LOCAL 220 select HAVE_CONTEXT_TRACKING_USER if X86_64 221 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 222 select HAVE_C_RECORDMCOUNT 223 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 224 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 225 select HAVE_BUILDTIME_MCOUNT_SORT 226 select HAVE_DEBUG_KMEMLEAK 227 select HAVE_DMA_CONTIGUOUS 228 select HAVE_DYNAMIC_FTRACE 229 select HAVE_DYNAMIC_FTRACE_WITH_REGS 230 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 231 select HAVE_FTRACE_REGS_HAVING_PT_REGS if X86_64 232 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 233 select HAVE_DYNAMIC_FTRACE_WITH_JMP if X86_64 234 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 235 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 236 select HAVE_EBPF_JIT 237 select HAVE_EFFICIENT_UNALIGNED_ACCESS 238 select HAVE_EISA if X86_32 239 select HAVE_EXIT_THREAD 240 select HAVE_GENERIC_TIF_BITS 241 select HAVE_GUP_FAST 242 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 243 select HAVE_FTRACE_GRAPH_FUNC if HAVE_FUNCTION_GRAPH_TRACER 244 select HAVE_FUNCTION_GRAPH_FREGS if HAVE_FUNCTION_GRAPH_TRACER 245 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 246 select HAVE_FUNCTION_TRACER 247 select HAVE_GCC_PLUGINS 248 select HAVE_HW_BREAKPOINT 249 select HAVE_IOREMAP_PROT 250 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 251 select HAVE_IRQ_TIME_ACCOUNTING 252 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 253 select HAVE_KERNEL_BZIP2 254 select HAVE_KERNEL_GZIP 255 select HAVE_KERNEL_LZ4 256 select HAVE_KERNEL_LZMA 257 select HAVE_KERNEL_LZO 258 select HAVE_KERNEL_XZ 259 select HAVE_KERNEL_ZSTD 260 select HAVE_KPROBES 261 select HAVE_KPROBES_ON_FTRACE 262 select HAVE_FUNCTION_ERROR_INJECTION 263 select HAVE_KRETPROBES 264 select HAVE_RETHOOK 265 select HAVE_KLP_BUILD if X86_64 266 select HAVE_LIVEPATCH if X86_64 267 select HAVE_MIXED_BREAKPOINTS_REGS 268 select HAVE_MOD_ARCH_SPECIFIC 269 select HAVE_MOVE_PMD 270 select HAVE_MOVE_PUD 271 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 272 select HAVE_NMI 273 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 274 select HAVE_OBJTOOL if X86_64 275 select HAVE_OPTPROBES 276 select HAVE_PAGE_SIZE_4KB 277 select HAVE_PCSPKR_PLATFORM 278 select HAVE_PERF_EVENTS 279 select HAVE_PERF_EVENTS_NMI 280 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 281 select HAVE_PCI 282 select HAVE_PERF_REGS 283 select HAVE_PERF_USER_STACK_DUMP 284 select ASYNC_KERNEL_PGTABLE_FREE if IOMMU_SVA 285 select MMU_GATHER_RCU_TABLE_FREE 286 select MMU_GATHER_MERGE_VMAS 287 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 288 select HAVE_REGS_AND_STACK_ACCESS_API 289 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 290 select HAVE_FUNCTION_ARG_ACCESS_API 291 select HAVE_SETUP_PER_CPU_AREA 292 select HAVE_SOFTIRQ_ON_OWN_STACK 293 select HAVE_STACKPROTECTOR 294 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 295 select HAVE_STATIC_CALL 296 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 297 select HAVE_PREEMPT_DYNAMIC_CALL 298 select HAVE_RSEQ 299 select HAVE_RUST if X86_64 300 select HAVE_SYSCALL_TRACEPOINTS 301 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 302 select HAVE_UNSTABLE_SCHED_CLOCK 303 select HAVE_UNWIND_USER_FP if X86_64 304 select HAVE_USER_RETURN_NOTIFIER 305 select HAVE_GENERIC_VDSO 306 select VDSO_GETRANDOM if X86_64 307 select HOTPLUG_PARALLEL if SMP && X86_64 308 select HOTPLUG_SMT if SMP 309 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 310 select IRQ_FORCED_THREADING 311 select LOCK_MM_AND_FIND_VMA 312 select NEED_PER_CPU_EMBED_FIRST_CHUNK 313 select NEED_PER_CPU_PAGE_FIRST_CHUNK 314 select NEED_SG_DMA_LENGTH 315 select NUMA_MEMBLKS if NUMA 316 select PCI_DOMAINS if PCI 317 select PCI_LOCKLESS_CONFIG if PCI 318 select PERF_EVENTS 319 select RTC_LIB 320 select RTC_MC146818_LIB 321 select SPARSE_IRQ 322 select SYSCTL_EXCEPTION_TRACE 323 select THREAD_INFO_IN_TASK 324 select TRACE_IRQFLAGS_SUPPORT 325 select TRACE_IRQFLAGS_NMI_SUPPORT 326 select USER_STACKTRACE_SUPPORT 327 select HAVE_ARCH_KCSAN if X86_64 328 select PROC_PID_ARCH_STATUS if PROC_FS 329 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 330 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 331 select FUNCTION_ALIGNMENT_4B 332 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 333 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 334 select ARCH_SUPPORTS_PT_RECLAIM if X86_64 335 select ARCH_SUPPORTS_SCHED_SMT if SMP 336 select SCHED_SMT if SMP 337 select ARCH_SUPPORTS_SCHED_CLUSTER if SMP 338 select ARCH_SUPPORTS_SCHED_MC if SMP 339 340config INSTRUCTION_DECODER 341 def_bool y 342 depends on KPROBES || PERF_EVENTS || UPROBES 343 344config OUTPUT_FORMAT 345 string 346 default "elf32-i386" if X86_32 347 default "elf64-x86-64" if X86_64 348 349config LOCKDEP_SUPPORT 350 def_bool y 351 352config STACKTRACE_SUPPORT 353 def_bool y 354 355config MMU 356 def_bool y 357 358config ARCH_MMAP_RND_BITS_MIN 359 default 28 if 64BIT 360 default 8 361 362config ARCH_MMAP_RND_BITS_MAX 363 default 32 if 64BIT 364 default 16 365 366config ARCH_MMAP_RND_COMPAT_BITS_MIN 367 default 8 368 369config ARCH_MMAP_RND_COMPAT_BITS_MAX 370 default 16 371 372config SBUS 373 bool 374 375config GENERIC_ISA_DMA 376 def_bool y 377 depends on ISA_DMA_API 378 379config GENERIC_CSUM 380 bool 381 default y if KMSAN || KASAN 382 383config GENERIC_BUG 384 def_bool y 385 depends on BUG 386 select GENERIC_BUG_RELATIVE_POINTERS 387 388config GENERIC_BUG_RELATIVE_POINTERS 389 bool 390 391config ARCH_MAY_HAVE_PC_FDC 392 def_bool y 393 depends on ISA_DMA_API 394 395config GENERIC_CALIBRATE_DELAY 396 def_bool y 397 398config ARCH_HAS_CPU_RELAX 399 def_bool y 400 401config ARCH_HIBERNATION_POSSIBLE 402 def_bool y 403 404config ARCH_SUSPEND_POSSIBLE 405 def_bool y 406 407config AUDIT_ARCH 408 def_bool y if X86_64 409 410config KASAN_SHADOW_OFFSET 411 hex 412 depends on KASAN 413 default 0xdffffc0000000000 414 415config HAVE_INTEL_TXT 416 def_bool y 417 depends on INTEL_IOMMU && ACPI 418 419config ARCH_SUPPORTS_UPROBES 420 def_bool y 421 422config FIX_EARLYCON_MEM 423 def_bool y 424 425config DYNAMIC_PHYSICAL_MASK 426 bool 427 428config PGTABLE_LEVELS 429 int 430 default 5 if X86_64 431 default 3 if X86_PAE 432 default 2 433 434menu "Processor type and features" 435 436config SMP 437 bool "Symmetric multi-processing support" 438 help 439 This enables support for systems with more than one CPU. If you have 440 a system with only one CPU, say N. If you have a system with more 441 than one CPU, say Y. 442 443 If you say N here, the kernel will run on uni- and multiprocessor 444 machines, but will use only one CPU of a multiprocessor machine. If 445 you say Y here, the kernel will run on many, but not all, 446 uniprocessor machines. On a uniprocessor machine, the kernel 447 will run faster if you say N here. 448 449 Note that if you say Y here and choose architecture "586" or 450 "Pentium" under "Processor family", the kernel will not work on 486 451 architectures. Similarly, multiprocessor kernels for the "PPro" 452 architecture may not work on all Pentium based boards. 453 454 People using multiprocessor machines who say Y here should also say 455 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 456 Management" code will be disabled if you say Y here. 457 458 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 459 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 460 <http://www.tldp.org/docs.html#howto>. 461 462 If you don't know what to do here, say N. 463 464config X86_X2APIC 465 bool "x2APIC interrupt controller architecture support" 466 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 467 default y 468 help 469 x2APIC is an interrupt controller architecture, a component of which 470 (the local APIC) is present in the CPU. It allows faster access to 471 the local APIC and supports a larger number of CPUs in the system 472 than the predecessors. 473 474 x2APIC was introduced in Intel CPUs around 2008 and in AMD EPYC CPUs 475 in 2019, but it can be disabled by the BIOS. It is also frequently 476 emulated in virtual machines, even when the host CPU does not support 477 it. Support in the CPU can be checked by executing 478 grep x2apic /proc/cpuinfo 479 480 If this configuration option is disabled, the kernel will boot with 481 very reduced functionality and performance on some platforms that 482 have x2APIC enabled. On the other hand, on hardware that does not 483 support x2APIC, a kernel with this option enabled will just fallback 484 to older APIC implementations. 485 486 If in doubt, say Y. 487 488config AMD_SECURE_AVIC 489 bool "AMD Secure AVIC" 490 depends on AMD_MEM_ENCRYPT && X86_X2APIC 491 help 492 Enable this to get AMD Secure AVIC support on guests that have this feature. 493 494 AMD Secure AVIC provides hardware acceleration for performance sensitive 495 APIC accesses and support for managing guest owned APIC state for SEV-SNP 496 guests. Secure AVIC does not support xAPIC mode. It has functional 497 dependency on x2apic being enabled in the guest. 498 499 If you don't know what to do here, say N. 500 501config X86_POSTED_MSI 502 bool "Enable MSI and MSI-x delivery by posted interrupts" 503 depends on X86_64 && IRQ_REMAP 504 help 505 This enables MSIs that are under interrupt remapping to be delivered as 506 posted interrupts to the host kernel. Interrupt throughput can 507 potentially be improved by coalescing CPU notifications during high 508 frequency bursts. 509 510 If you don't know what to do here, say N. 511 512config X86_MPPARSE 513 bool "Enable MPS table" if ACPI 514 default y 515 depends on X86_LOCAL_APIC 516 help 517 For old smp systems that do not have proper acpi support. Newer systems 518 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 519 520config X86_CPU_RESCTRL 521 bool "x86 CPU resource control support" 522 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 523 depends on MISC_FILESYSTEMS 524 select ARCH_HAS_CPU_RESCTRL 525 select RESCTRL_FS 526 select RESCTRL_FS_PSEUDO_LOCK 527 help 528 Enable x86 CPU resource control support. 529 530 Provide support for the allocation and monitoring of system resources 531 usage by the CPU. 532 533 Intel calls this Intel Resource Director Technology 534 (Intel(R) RDT). More information about RDT can be found in the 535 Intel x86 Architecture Software Developer Manual. 536 537 AMD calls this AMD Platform Quality of Service (AMD QoS). 538 More information about AMD QoS can be found in the AMD64 Technology 539 Platform Quality of Service Extensions manual. 540 541 Say N if unsure. 542 543config X86_FRED 544 bool "Flexible Return and Event Delivery" 545 depends on X86_64 546 help 547 When enabled, try to use Flexible Return and Event Delivery 548 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 549 ring transitions and exception/interrupt handling if the 550 system supports it. 551 552config X86_EXTENDED_PLATFORM 553 bool "Support for extended (non-PC) x86 platforms" 554 default y 555 help 556 If you disable this option then the kernel will only support 557 standard PC platforms. (which covers the vast majority of 558 systems out there.) 559 560 If you enable this option then you'll be able to select support 561 for the following non-PC x86 platforms, depending on the value of 562 CONFIG_64BIT. 563 564 32-bit platforms (CONFIG_64BIT=n): 565 Goldfish (mostly Android emulator) 566 Intel CE media processor (CE4100) SoC 567 Intel Quark 568 RDC R-321x SoC 569 570 64-bit platforms (CONFIG_64BIT=y): 571 Numascale NumaChip 572 ScaleMP vSMP 573 SGI Ultraviolet 574 Merrifield/Moorefield MID devices 575 Goldfish (mostly Android emulator) 576 577 If you have one of these systems, or if you want to build a 578 generic distribution kernel, say Y here - otherwise say N. 579 580# This is an alphabetically sorted list of 64 bit extended platforms 581# Please maintain the alphabetic order if and when there are additions 582config X86_NUMACHIP 583 bool "Numascale NumaChip" 584 depends on X86_64 585 depends on X86_EXTENDED_PLATFORM 586 depends on NUMA 587 depends on SMP 588 depends on X86_X2APIC 589 depends on PCI_MMCONFIG 590 help 591 Adds support for Numascale NumaChip large-SMP systems. Needed to 592 enable more than ~168 cores. 593 If you don't have one of these, you should say N here. 594 595config X86_VSMP 596 bool "ScaleMP vSMP" 597 select HYPERVISOR_GUEST 598 select PARAVIRT 599 depends on X86_64 && PCI 600 depends on X86_EXTENDED_PLATFORM 601 depends on SMP 602 help 603 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 604 supposed to run on these EM64T-based machines. Only choose this option 605 if you have one of these machines. 606 607config X86_UV 608 bool "SGI Ultraviolet" 609 depends on X86_64 610 depends on X86_EXTENDED_PLATFORM 611 depends on NUMA 612 depends on EFI 613 depends on KEXEC_CORE 614 depends on X86_X2APIC 615 depends on PCI 616 help 617 This option is needed in order to support SGI Ultraviolet systems. 618 If you don't have one of these, you should say N here. 619 620config X86_INTEL_MID 621 bool "Intel Z34xx/Z35xx MID platform support" 622 depends on X86_EXTENDED_PLATFORM 623 depends on X86_PLATFORM_DEVICES 624 depends on PCI 625 depends on X86_64 || (EXPERT && PCI_GOANY) 626 depends on X86_IO_APIC 627 select I2C 628 select DW_APB_TIMER 629 select INTEL_SCU_PCI 630 help 631 Select to build a kernel capable of supporting 64-bit Intel MID 632 (Mobile Internet Device) platform systems which do not have 633 the PCI legacy interfaces. 634 635 The only supported devices are the 22nm Merrified (Z34xx) 636 and Moorefield (Z35xx) SoC used in the Intel Edison board and 637 a small number of Android devices such as the Asus Zenfone 2, 638 Asus FonePad 8 and Dell Venue 7. 639 640 If you are building for a PC class system or non-MID tablet 641 SoCs like Bay Trail (Z36xx/Z37xx), say N here. 642 643 Intel MID platforms are based on an Intel processor and chipset which 644 consume less power than most of the x86 derivatives. 645 646config X86_GOLDFISH 647 bool "Goldfish (Virtual Platform)" 648 depends on X86_EXTENDED_PLATFORM 649 help 650 Enable support for the Goldfish virtual platform used primarily 651 for Android development. Unless you are building for the Android 652 Goldfish emulator say N here. 653 654# Following is an alphabetically sorted list of 32 bit extended platforms 655# Please maintain the alphabetic order if and when there are additions 656 657config X86_INTEL_CE 658 bool "CE4100 TV platform" 659 depends on PCI 660 depends on PCI_GODIRECT 661 depends on X86_IO_APIC 662 depends on X86_32 663 depends on X86_EXTENDED_PLATFORM 664 select X86_REBOOTFIXUPS 665 select OF 666 select OF_EARLY_FLATTREE 667 help 668 Select for the Intel CE media processor (CE4100) SOC. 669 This option compiles in support for the CE4100 SOC for settop 670 boxes and media devices. 671 672config X86_INTEL_QUARK 673 bool "Intel Quark platform support" 674 depends on X86_32 675 depends on X86_EXTENDED_PLATFORM 676 depends on X86_PLATFORM_DEVICES 677 depends on X86_TSC 678 depends on PCI 679 depends on PCI_GOANY 680 depends on X86_IO_APIC 681 select IOSF_MBI 682 select INTEL_IMR 683 select COMMON_CLK 684 help 685 Select to include support for Quark X1000 SoC. 686 Say Y here if you have a Quark based system such as the Arduino 687 compatible Intel Galileo. 688 689config X86_RDC321X 690 bool "RDC R-321x SoC" 691 depends on X86_32 692 depends on X86_EXTENDED_PLATFORM 693 select M486 694 select X86_REBOOTFIXUPS 695 help 696 This option is needed for RDC R-321x system-on-chip, also known 697 as R-8610-(G). 698 If you don't have one of these chips, you should say N here. 699 700config X86_INTEL_LPSS 701 bool "Intel Low Power Subsystem Support" 702 depends on X86 && ACPI && PCI 703 select COMMON_CLK 704 select PINCTRL 705 select IOSF_MBI 706 help 707 Select to build support for Intel Low Power Subsystem such as 708 found on Intel Lynxpoint PCH. Selecting this option enables 709 things like clock tree (common clock framework) and pincontrol 710 which are needed by the LPSS peripheral drivers. 711 712config X86_AMD_PLATFORM_DEVICE 713 bool "AMD ACPI2Platform devices support" 714 depends on ACPI 715 select COMMON_CLK 716 select PINCTRL 717 help 718 Select to interpret AMD specific ACPI device to platform device 719 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 720 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 721 implemented under PINCTRL subsystem. 722 723config IOSF_MBI 724 tristate "Intel SoC IOSF Sideband support for SoC platforms" 725 depends on PCI 726 help 727 This option enables sideband register access support for Intel SoC 728 platforms. On these platforms the IOSF sideband is used in lieu of 729 MSR's for some register accesses, mostly but not limited to thermal 730 and power. Drivers may query the availability of this device to 731 determine if they need the sideband in order to work on these 732 platforms. The sideband is available on the following SoC products. 733 This list is not meant to be exclusive. 734 - BayTrail 735 - Braswell 736 - Quark 737 738 You should say Y if you are running a kernel on one of these SoC's. 739 740config IOSF_MBI_DEBUG 741 bool "Enable IOSF sideband access through debugfs" 742 depends on IOSF_MBI && DEBUG_FS 743 help 744 Select this option to expose the IOSF sideband access registers (MCR, 745 MDR, MCRX) through debugfs to write and read register information from 746 different units on the SoC. This is most useful for obtaining device 747 state information for debug and analysis. As this is a general access 748 mechanism, users of this option would have specific knowledge of the 749 device they want to access. 750 751 If you don't require the option or are in doubt, say N. 752 753config X86_SUPPORTS_MEMORY_FAILURE 754 def_bool y 755 # MCE code calls memory_failure(): 756 depends on X86_MCE 757 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 758 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 759 depends on X86_64 || !SPARSEMEM 760 select ARCH_SUPPORTS_MEMORY_FAILURE 761 762config X86_32_IRIS 763 tristate "Eurobraille/Iris poweroff module" 764 depends on X86_32 765 help 766 The Iris machines from EuroBraille do not have APM or ACPI support 767 to shut themselves down properly. A special I/O sequence is 768 needed to do so, which is what this module does at 769 kernel shutdown. 770 771 This is only for Iris machines from EuroBraille. 772 773 If unused, say N. 774 775config SCHED_OMIT_FRAME_POINTER 776 def_bool y 777 prompt "Single-depth WCHAN output" 778 depends on X86 779 help 780 Calculate simpler /proc/<PID>/wchan values. If this option 781 is disabled then wchan values will recurse back to the 782 caller function. This provides more accurate wchan values, 783 at the expense of slightly more scheduling overhead. 784 785 If in doubt, say "Y". 786 787menuconfig HYPERVISOR_GUEST 788 bool "Linux guest support" 789 help 790 Say Y here to enable options for running Linux under various hyper- 791 visors. This option enables basic hypervisor detection and platform 792 setup. 793 794 If you say N, all options in this submenu will be skipped and 795 disabled, and Linux guest support won't be built in. 796 797if HYPERVISOR_GUEST 798 799config PARAVIRT 800 bool "Enable paravirtualization code" 801 depends on HAVE_STATIC_CALL 802 select HAVE_PV_STEAL_CLOCK_GEN 803 help 804 This changes the kernel so it can modify itself when it is run 805 under a hypervisor, potentially improving performance significantly 806 over full virtualization. However, when run without a hypervisor 807 the kernel is theoretically slower and slightly larger. 808 809config PARAVIRT_XXL 810 bool 811 depends on X86_64 812 813config PARAVIRT_SPINLOCKS 814 bool "Paravirtualization layer for spinlocks" 815 depends on PARAVIRT && SMP 816 help 817 Paravirtualized spinlocks allow a pvops backend to replace the 818 spinlock implementation with something virtualization-friendly 819 (for example, block the virtual CPU rather than spinning). 820 821 It has a minimal impact on native kernels and gives a nice performance 822 benefit on paravirtualized KVM / Xen kernels. 823 824 If you are unsure how to answer this question, answer Y. 825 826config X86_HV_CALLBACK_VECTOR 827 def_bool n 828 829source "arch/x86/xen/Kconfig" 830 831config KVM_GUEST 832 bool "KVM Guest support (including kvmclock)" 833 depends on PARAVIRT 834 select PARAVIRT_CLOCK 835 select ARCH_CPUIDLE_HALTPOLL 836 select X86_HV_CALLBACK_VECTOR 837 default y 838 help 839 This option enables various optimizations for running under the KVM 840 hypervisor. It includes a paravirtualized clock, so that instead 841 of relying on a PIT (or probably other) emulation by the 842 underlying device model, the host provides the guest with 843 timing infrastructure such as time of day, and system time 844 845config ARCH_CPUIDLE_HALTPOLL 846 def_bool n 847 prompt "Disable host haltpoll when loading haltpoll driver" 848 help 849 If virtualized under KVM, disable host haltpoll. 850 851config PVH 852 bool "Support for running PVH guests" 853 help 854 This option enables the PVH entry point for guest virtual machines 855 as specified in the x86/HVM direct boot ABI. 856 857config PARAVIRT_TIME_ACCOUNTING 858 bool "Paravirtual steal time accounting" 859 depends on PARAVIRT 860 help 861 Select this option to enable fine granularity task steal time 862 accounting. Time spent executing other tasks in parallel with 863 the current vCPU is discounted from the vCPU power. To account for 864 that, there can be a small performance impact. 865 866 If in doubt, say N here. 867 868config PARAVIRT_CLOCK 869 bool 870 871config JAILHOUSE_GUEST 872 bool "Jailhouse non-root cell support" 873 depends on X86_64 && PCI 874 select X86_PM_TIMER 875 help 876 This option allows to run Linux as guest in a Jailhouse non-root 877 cell. You can leave this option disabled if you only want to start 878 Jailhouse and run Linux afterwards in the root cell. 879 880config ACRN_GUEST 881 bool "ACRN Guest support" 882 depends on X86_64 883 select X86_HV_CALLBACK_VECTOR 884 help 885 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 886 a flexible, lightweight reference open-source hypervisor, built with 887 real-time and safety-criticality in mind. It is built for embedded 888 IOT with small footprint and real-time features. More details can be 889 found in https://projectacrn.org/. 890 891config BHYVE_GUEST 892 bool "Bhyve (BSD Hypervisor) Guest support" 893 depends on X86_64 894 help 895 This option allows to run Linux to recognise when it is running as a 896 guest in the Bhyve hypervisor, and to support more than 255 vCPUs when 897 when doing so. More details about Bhyve can be found at https://bhyve.org 898 and https://wiki.freebsd.org/bhyve/. 899 900config INTEL_TDX_GUEST 901 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 902 depends on X86_64 && CPU_SUP_INTEL 903 depends on X86_X2APIC 904 depends on EFI_STUB 905 depends on PARAVIRT 906 select ARCH_HAS_CC_PLATFORM 907 select X86_MEM_ENCRYPT 908 select X86_MCE 909 select UNACCEPTED_MEMORY 910 help 911 Support running as a guest under Intel TDX. Without this support, 912 the guest kernel can not boot or run under TDX. 913 TDX includes memory encryption and integrity capabilities 914 which protect the confidentiality and integrity of guest 915 memory contents and CPU state. TDX guests are protected from 916 some attacks from the VMM. 917 918endif # HYPERVISOR_GUEST 919 920source "arch/x86/Kconfig.cpu" 921 922config HPET_TIMER 923 def_bool X86_64 924 prompt "HPET Timer Support" if X86_32 925 help 926 Use the IA-PC HPET (High Precision Event Timer) to manage 927 time in preference to the PIT and RTC, if a HPET is 928 present. 929 HPET is the next generation timer replacing legacy 8254s. 930 The HPET provides a stable time base on SMP 931 systems, unlike the TSC, but it is more expensive to access, 932 as it is off-chip. The interface used is documented 933 in the HPET spec, revision 1. 934 935 You can safely choose Y here. However, HPET will only be 936 activated if the platform and the BIOS support this feature. 937 Otherwise the 8254 will be used for timing services. 938 939 Choose N to continue using the legacy 8254 timer. 940 941config HPET_EMULATE_RTC 942 def_bool y 943 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 944 945# Mark as expert because too many people got it wrong. 946# The code disables itself when not needed. 947config DMI 948 default y 949 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 950 bool "Enable DMI scanning" if EXPERT 951 help 952 Enabled scanning of DMI to identify machine quirks. Say Y 953 here unless you have verified that your setup is not 954 affected by entries in the DMI blacklist. Required by PNP 955 BIOS code. 956 957config GART_IOMMU 958 bool "Old AMD GART IOMMU support" 959 select IOMMU_HELPER 960 select SWIOTLB 961 depends on X86_64 && PCI && AMD_NB 962 help 963 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 964 GART based hardware IOMMUs. 965 966 The GART supports full DMA access for devices with 32-bit access 967 limitations, on systems with more than 3 GB. This is usually needed 968 for USB, sound, many IDE/SATA chipsets and some other devices. 969 970 Newer systems typically have a modern AMD IOMMU, supported via 971 the CONFIG_AMD_IOMMU=y config option. 972 973 In normal configurations this driver is only active when needed: 974 there's more than 3 GB of memory and the system contains a 975 32-bit limited device. 976 977 If unsure, say Y. 978 979config BOOT_VESA_SUPPORT 980 bool 981 help 982 If true, at least one selected framebuffer driver can take advantage 983 of VESA video modes set at an early boot stage via the vga= parameter. 984 985config MAXSMP 986 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 987 depends on X86_64 && SMP && DEBUG_KERNEL 988 select CPUMASK_OFFSTACK 989 help 990 Enable maximum number of CPUS and NUMA Nodes for this architecture. 991 If unsure, say N. 992 993# 994# The maximum number of CPUs supported: 995# 996# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 997# and which can be configured interactively in the 998# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 999# 1000# The ranges are different on 32-bit and 64-bit kernels, depending on 1001# hardware capabilities and scalability features of the kernel. 1002# 1003# ( If MAXSMP is enabled we just use the highest possible value and disable 1004# interactive configuration. ) 1005# 1006 1007config NR_CPUS_RANGE_BEGIN 1008 int 1009 default NR_CPUS_RANGE_END if MAXSMP 1010 default 1 if !SMP 1011 default 2 1012 1013config NR_CPUS_RANGE_END 1014 int 1015 depends on X86_32 1016 default 8 if SMP 1017 default 1 if !SMP 1018 1019config NR_CPUS_RANGE_END 1020 int 1021 depends on X86_64 1022 default 8192 if SMP && CPUMASK_OFFSTACK 1023 default 512 if SMP && !CPUMASK_OFFSTACK 1024 default 1 if !SMP 1025 1026config NR_CPUS_DEFAULT 1027 int 1028 depends on X86_32 1029 default 8 if SMP 1030 default 1 if !SMP 1031 1032config NR_CPUS_DEFAULT 1033 int 1034 depends on X86_64 1035 default 8192 if MAXSMP 1036 default 64 if SMP 1037 default 1 if !SMP 1038 1039config NR_CPUS 1040 int "Maximum number of CPUs" if SMP && !MAXSMP 1041 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1042 default NR_CPUS_DEFAULT 1043 help 1044 This allows you to specify the maximum number of CPUs which this 1045 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1046 supported value is 8192, otherwise the maximum value is 512. The 1047 minimum value which makes sense is 2. 1048 1049 This is purely to save memory: each supported CPU adds about 8KB 1050 to the kernel image. 1051 1052config SCHED_MC_PRIO 1053 bool "CPU core priorities scheduler support" 1054 depends on SCHED_MC 1055 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1056 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1057 select CPU_FREQ 1058 default y 1059 help 1060 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1061 core ordering determined at manufacturing time, which allows 1062 certain cores to reach higher turbo frequencies (when running 1063 single threaded workloads) than others. 1064 1065 Enabling this kernel feature teaches the scheduler about 1066 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1067 scheduler's CPU selection logic accordingly, so that higher 1068 overall system performance can be achieved. 1069 1070 This feature will have no effect on CPUs without this feature. 1071 1072 If unsure say Y here. 1073 1074config UP_LATE_INIT 1075 def_bool y 1076 depends on !SMP && X86_LOCAL_APIC 1077 1078config X86_UP_APIC 1079 bool "Local APIC support on uniprocessors" if !PCI_MSI 1080 default PCI_MSI 1081 depends on X86_32 && !SMP 1082 help 1083 A local APIC (Advanced Programmable Interrupt Controller) is an 1084 integrated interrupt controller in the CPU. If you have a single-CPU 1085 system which has a processor with a local APIC, you can say Y here to 1086 enable and use it. If you say Y here even though your machine doesn't 1087 have a local APIC, then the kernel will still run with no slowdown at 1088 all. The local APIC supports CPU-generated self-interrupts (timer, 1089 performance counters), and the NMI watchdog which detects hard 1090 lockups. 1091 1092config X86_UP_IOAPIC 1093 bool "IO-APIC support on uniprocessors" 1094 depends on X86_UP_APIC 1095 help 1096 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1097 SMP-capable replacement for PC-style interrupt controllers. Most 1098 SMP systems and many recent uniprocessor systems have one. 1099 1100 If you have a single-CPU system with an IO-APIC, you can say Y here 1101 to use it. If you say Y here even though your machine doesn't have 1102 an IO-APIC, then the kernel will still run with no slowdown at all. 1103 1104config X86_LOCAL_APIC 1105 def_bool y 1106 depends on X86_64 || SMP || X86_UP_APIC || PCI_MSI 1107 select IRQ_DOMAIN_HIERARCHY 1108 1109config ACPI_MADT_WAKEUP 1110 def_bool y 1111 depends on X86_64 1112 depends on ACPI 1113 depends on SMP 1114 depends on X86_LOCAL_APIC 1115 1116config X86_IO_APIC 1117 def_bool y 1118 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1119 1120config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1121 bool "Reroute for broken boot IRQs" 1122 depends on X86_IO_APIC 1123 help 1124 This option enables a workaround that fixes a source of 1125 spurious interrupts. This is recommended when threaded 1126 interrupt handling is used on systems where the generation of 1127 superfluous "boot interrupts" cannot be disabled. 1128 1129 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1130 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1131 kernel does during interrupt handling). On chipsets where this 1132 boot IRQ generation cannot be disabled, this workaround keeps 1133 the original IRQ line masked so that only the equivalent "boot 1134 IRQ" is delivered to the CPUs. The workaround also tells the 1135 kernel to set up the IRQ handler on the boot IRQ line. In this 1136 way only one interrupt is delivered to the kernel. Otherwise 1137 the spurious second interrupt may cause the kernel to bring 1138 down (vital) interrupt lines. 1139 1140 Only affects "broken" chipsets. Interrupt sharing may be 1141 increased on these systems. 1142 1143config X86_MCE 1144 bool "Machine Check / overheating reporting" 1145 select GENERIC_ALLOCATOR 1146 default y 1147 help 1148 Machine Check support allows the processor to notify the 1149 kernel if it detects a problem (e.g. overheating, data corruption). 1150 The action the kernel takes depends on the severity of the problem, 1151 ranging from warning messages to halting the machine. 1152 1153config X86_MCELOG_LEGACY 1154 bool "Support for deprecated /dev/mcelog character device" 1155 depends on X86_MCE 1156 help 1157 Enable support for /dev/mcelog which is needed by the old mcelog 1158 userspace logging daemon. Consider switching to the new generation 1159 rasdaemon solution. 1160 1161config X86_MCE_INTEL 1162 def_bool y 1163 prompt "Intel MCE features" 1164 depends on X86_MCE && X86_LOCAL_APIC 1165 help 1166 Additional support for intel specific MCE features such as 1167 the thermal monitor. 1168 1169config X86_MCE_AMD 1170 def_bool y 1171 prompt "AMD MCE features" 1172 depends on X86_MCE && X86_LOCAL_APIC 1173 help 1174 Additional support for AMD specific MCE features such as 1175 the DRAM Error Threshold. 1176 1177config X86_ANCIENT_MCE 1178 bool "Support for old Pentium 5 / WinChip machine checks" 1179 depends on X86_32 && X86_MCE 1180 help 1181 Include support for machine check handling on old Pentium 5 or WinChip 1182 systems. These typically need to be enabled explicitly on the command 1183 line. 1184 1185config X86_MCE_THRESHOLD 1186 depends on X86_MCE_AMD || X86_MCE_INTEL 1187 def_bool y 1188 1189config X86_MCE_INJECT 1190 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1191 tristate "Machine check injector support" 1192 help 1193 Provide support for injecting machine checks for testing purposes. 1194 If you don't know what a machine check is and you don't do kernel 1195 QA it is safe to say n. 1196 1197source "arch/x86/events/Kconfig" 1198 1199config X86_LEGACY_VM86 1200 bool "Legacy VM86 support" 1201 depends on X86_32 1202 help 1203 This option allows user programs to put the CPU into V8086 1204 mode, which is an 80286-era approximation of 16-bit real mode. 1205 1206 Some very old versions of X and/or vbetool require this option 1207 for user mode setting. Similarly, DOSEMU will use it if 1208 available to accelerate real mode DOS programs. However, any 1209 recent version of DOSEMU, X, or vbetool should be fully 1210 functional even without kernel VM86 support, as they will all 1211 fall back to software emulation. Nevertheless, if you are using 1212 a 16-bit DOS program where 16-bit performance matters, vm86 1213 mode might be faster than emulation and you might want to 1214 enable this option. 1215 1216 Note that any app that works on a 64-bit kernel is unlikely to 1217 need this option, as 64-bit kernels don't, and can't, support 1218 V8086 mode. This option is also unrelated to 16-bit protected 1219 mode and is not needed to run most 16-bit programs under Wine. 1220 1221 Enabling this option increases the complexity of the kernel 1222 and slows down exception handling a tiny bit. 1223 1224 If unsure, say N here. 1225 1226config VM86 1227 bool 1228 default X86_LEGACY_VM86 1229 1230config X86_16BIT 1231 bool "Enable support for 16-bit segments" if EXPERT 1232 default y 1233 depends on MODIFY_LDT_SYSCALL 1234 help 1235 This option is required by programs like Wine to run 16-bit 1236 protected mode legacy code on x86 processors. Disabling 1237 this option saves about 300 bytes on i386, or around 6K text 1238 plus 16K runtime memory on x86-64, 1239 1240config X86_ESPFIX32 1241 def_bool y 1242 depends on X86_16BIT && X86_32 1243 1244config X86_ESPFIX64 1245 def_bool y 1246 depends on X86_16BIT && X86_64 1247 1248config X86_VSYSCALL_EMULATION 1249 bool "Enable vsyscall emulation" if EXPERT 1250 default y 1251 depends on X86_64 1252 help 1253 This enables emulation of the legacy vsyscall page. Disabling 1254 it is roughly equivalent to booting with vsyscall=none, except 1255 that it will also disable the helpful warning if a program 1256 tries to use a vsyscall. With this option set to N, offending 1257 programs will just segfault, citing addresses of the form 1258 0xffffffffff600?00. 1259 1260 This option is required by many programs built before 2013, and 1261 care should be used even with newer programs if set to N. 1262 1263 Disabling this option saves about 7K of kernel size and 1264 possibly 4K of additional runtime pagetable memory. 1265 1266config X86_IOPL_IOPERM 1267 bool "IOPERM and IOPL Emulation" 1268 default y 1269 help 1270 This enables the ioperm() and iopl() syscalls which are necessary 1271 for legacy applications. 1272 1273 Legacy IOPL support is an overbroad mechanism which allows user 1274 space aside of accessing all 65536 I/O ports also to disable 1275 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1276 capabilities and permission from potentially active security 1277 modules. 1278 1279 The emulation restricts the functionality of the syscall to 1280 only allowing the full range I/O port access, but prevents the 1281 ability to disable interrupts from user space which would be 1282 granted if the hardware IOPL mechanism would be used. 1283 1284config TOSHIBA 1285 tristate "Toshiba Laptop support" 1286 depends on X86_32 1287 help 1288 This adds a driver to safely access the System Management Mode of 1289 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1290 not work on models with a Phoenix BIOS. The System Management Mode 1291 is used to set the BIOS and power saving options on Toshiba portables. 1292 1293 For information on utilities to make use of this driver see the 1294 Toshiba Linux utilities web site at: 1295 <http://www.buzzard.org.uk/toshiba/>. 1296 1297 Say Y if you intend to run this kernel on a Toshiba portable. 1298 Say N otherwise. 1299 1300config X86_REBOOTFIXUPS 1301 bool "Enable X86 board specific fixups for reboot" 1302 depends on X86_32 1303 help 1304 This enables chipset and/or board specific fixups to be done 1305 in order to get reboot to work correctly. This is only needed on 1306 some combinations of hardware and BIOS. The symptom, for which 1307 this config is intended, is when reboot ends with a stalled/hung 1308 system. 1309 1310 Currently, the only fixup is for the Geode machines using 1311 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1312 1313 Say Y if you want to enable the fixup. Currently, it's safe to 1314 enable this option even if you don't need it. 1315 Say N otherwise. 1316 1317config MICROCODE 1318 def_bool y 1319 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1320 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD 1321 1322config MICROCODE_INITRD32 1323 def_bool y 1324 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1325 1326config MICROCODE_LATE_LOADING 1327 bool "Late microcode loading (DANGEROUS)" 1328 default n 1329 depends on MICROCODE && SMP 1330 help 1331 Loading microcode late, when the system is up and executing instructions 1332 is a tricky business and should be avoided if possible. Just the sequence 1333 of synchronizing all cores and SMT threads is one fragile dance which does 1334 not guarantee that cores might not softlock after the loading. Therefore, 1335 use this at your own risk. Late loading taints the kernel unless the 1336 microcode header indicates that it is safe for late loading via the 1337 minimal revision check. This minimal revision check can be enforced on 1338 the kernel command line with "microcode=force_minrev". 1339 1340config MICROCODE_LATE_FORCE_MINREV 1341 bool "Enforce late microcode loading minimal revision check" 1342 default n 1343 depends on MICROCODE_LATE_LOADING 1344 help 1345 To prevent that users load microcode late which modifies already 1346 in use features, newer microcode patches have a minimum revision field 1347 in the microcode header, which tells the kernel which minimum 1348 revision must be active in the CPU to safely load that new microcode 1349 late into the running system. If disabled the check will not 1350 be enforced but the kernel will be tainted when the minimal 1351 revision check fails. 1352 1353 This minimal revision check can also be controlled via the 1354 "microcode=force_minrev" parameter on the kernel command line. 1355 1356 If unsure say Y. 1357 1358config MICROCODE_DBG 1359 bool "Enable microcode loader debugging" 1360 default n 1361 depends on MICROCODE 1362 help 1363 Enable code which allows for debugging the microcode loader in 1364 a guest. Meaning the patch loading is simulated but everything else 1365 related to patch parsing and handling is done as on baremetal with 1366 the purpose of debugging solely the software side of things. 1367 1368 You almost certainly want to say n here. 1369 1370config X86_MSR 1371 tristate "/dev/cpu/*/msr - Model-specific register support" 1372 help 1373 This device gives privileged processes access to the x86 1374 Model-Specific Registers (MSRs). It is a character device with 1375 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1376 MSR accesses are directed to a specific CPU on multi-processor 1377 systems. 1378 1379config X86_CPUID 1380 tristate "/dev/cpu/*/cpuid - CPU information support" 1381 help 1382 This device gives processes access to the x86 CPUID instruction to 1383 be executed on a specific processor. It is a character device 1384 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1385 /dev/cpu/31/cpuid. 1386 1387config HIGHMEM4G 1388 bool "High Memory Support" 1389 depends on X86_32 1390 help 1391 Linux can use up to 4 Gigabytes of physical memory on x86 systems. 1392 However, the address space of 32-bit x86 processors is only 4 1393 Gigabytes large. That means that, if you have a large amount of 1394 physical memory, not all of it can be "permanently mapped" by the 1395 kernel. The physical memory that's not permanently mapped is called 1396 "high memory". 1397 1398 If you are compiling a kernel which will never run on a machine with 1399 more than 1 Gigabyte total physical RAM, answer "off" here (default 1400 choice and suitable for most users). This will result in a "3GB/1GB" 1401 split: 3GB are mapped so that each process sees a 3GB virtual memory 1402 space and the remaining part of the 4GB virtual memory space is used 1403 by the kernel to permanently map as much physical memory as 1404 possible. 1405 1406 If the machine has between 1 and 4 Gigabytes physical RAM, then 1407 answer "Y" here. 1408 1409 If unsure, say N. 1410 1411choice 1412 prompt "Memory split" if EXPERT 1413 default VMSPLIT_3G 1414 depends on X86_32 1415 help 1416 Select the desired split between kernel and user memory. 1417 1418 If the address range available to the kernel is less than the 1419 physical memory installed, the remaining memory will be available 1420 as "high memory". Accessing high memory is a little more costly 1421 than low memory, as it needs to be mapped into the kernel first. 1422 Note that increasing the kernel address space limits the range 1423 available to user programs, making the address space there 1424 tighter. Selecting anything other than the default 3G/1G split 1425 will also likely make your kernel incompatible with binary-only 1426 kernel modules. 1427 1428 If you are not absolutely sure what you are doing, leave this 1429 option alone! 1430 1431 config VMSPLIT_3G 1432 bool "3G/1G user/kernel split" 1433 config VMSPLIT_3G_OPT 1434 depends on !X86_PAE 1435 bool "3G/1G user/kernel split (for full 1G low memory)" 1436 config VMSPLIT_2G 1437 bool "2G/2G user/kernel split" 1438 config VMSPLIT_2G_OPT 1439 depends on !X86_PAE 1440 bool "2G/2G user/kernel split (for full 2G low memory)" 1441 config VMSPLIT_1G 1442 bool "1G/3G user/kernel split" 1443endchoice 1444 1445config PAGE_OFFSET 1446 hex 1447 default 0xB0000000 if VMSPLIT_3G_OPT 1448 default 0x80000000 if VMSPLIT_2G 1449 default 0x78000000 if VMSPLIT_2G_OPT 1450 default 0x40000000 if VMSPLIT_1G 1451 default 0xC0000000 1452 depends on X86_32 1453 1454config HIGHMEM 1455 def_bool HIGHMEM4G 1456 1457config X86_PAE 1458 bool "PAE (Physical Address Extension) Support" 1459 depends on X86_32 && X86_HAVE_PAE 1460 select PHYS_ADDR_T_64BIT 1461 help 1462 PAE is required for NX support, and furthermore enables 1463 larger swapspace support for non-overcommit purposes. It 1464 has the cost of more pagetable lookup overhead, and also 1465 consumes more pagetable space per process. 1466 1467config X86_DIRECT_GBPAGES 1468 def_bool y 1469 depends on X86_64 1470 help 1471 Certain kernel features effectively disable kernel 1472 linear 1 GB mappings (even if the CPU otherwise 1473 supports them), so don't confuse the user by printing 1474 that we have them enabled. 1475 1476config X86_CPA_STATISTICS 1477 bool "Enable statistic for Change Page Attribute" 1478 depends on DEBUG_FS 1479 help 1480 Expose statistics about the Change Page Attribute mechanism, which 1481 helps to determine the effectiveness of preserving large and huge 1482 page mappings when mapping protections are changed. 1483 1484config X86_MEM_ENCRYPT 1485 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1486 select DYNAMIC_PHYSICAL_MASK 1487 def_bool n 1488 1489config AMD_MEM_ENCRYPT 1490 bool "AMD Secure Memory Encryption (SME) support" 1491 depends on X86_64 && CPU_SUP_AMD 1492 depends on EFI_STUB 1493 select DMA_COHERENT_POOL 1494 select ARCH_USE_MEMREMAP_PROT 1495 select INSTRUCTION_DECODER 1496 select ARCH_HAS_CC_PLATFORM 1497 select X86_MEM_ENCRYPT 1498 select UNACCEPTED_MEMORY 1499 select CRYPTO_LIB_AESGCM 1500 help 1501 Say yes to enable support for the encryption of system memory. 1502 This requires an AMD processor that supports Secure Memory 1503 Encryption (SME). 1504 1505# Common NUMA Features 1506config NUMA 1507 bool "NUMA Memory Allocation and Scheduler Support" 1508 depends on SMP 1509 depends on X86_64 1510 select USE_PERCPU_NUMA_NODE_ID 1511 select OF_NUMA if OF 1512 help 1513 Enable NUMA (Non-Uniform Memory Access) support. 1514 1515 The kernel will try to allocate memory used by a CPU on the 1516 local memory controller of the CPU and add some more 1517 NUMA awareness to the kernel. 1518 1519 For 64-bit this is recommended if the system is Intel Core i7 1520 (or later), AMD Opteron, or EM64T NUMA. 1521 1522 Otherwise, you should say N. 1523 1524config AMD_NUMA 1525 def_bool y 1526 prompt "Old style AMD Opteron NUMA detection" 1527 depends on X86_64 && NUMA && PCI 1528 help 1529 Enable AMD NUMA node topology detection. You should say Y here if 1530 you have a multi processor AMD system. This uses an old method to 1531 read the NUMA configuration directly from the builtin Northbridge 1532 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1533 which also takes priority if both are compiled in. 1534 1535config X86_64_ACPI_NUMA 1536 def_bool y 1537 prompt "ACPI NUMA detection" 1538 depends on X86_64 && NUMA && ACPI && PCI 1539 select ACPI_NUMA 1540 help 1541 Enable ACPI SRAT based node topology detection. 1542 1543config NODES_SHIFT 1544 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1545 range 1 10 1546 default "10" if MAXSMP 1547 default "6" if X86_64 1548 default "3" 1549 depends on NUMA 1550 help 1551 Specify the maximum number of NUMA Nodes available on the target 1552 system. Increases memory reserved to accommodate various tables. 1553 1554config ARCH_FLATMEM_ENABLE 1555 def_bool y 1556 depends on X86_32 && !NUMA 1557 1558config ARCH_SPARSEMEM_ENABLE 1559 def_bool y 1560 select SPARSEMEM_STATIC if X86_32 1561 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1562 1563config ARCH_SPARSEMEM_DEFAULT 1564 def_bool X86_64 || (NUMA && X86_32) 1565 1566config ARCH_SELECT_MEMORY_MODEL 1567 def_bool y 1568 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1569 1570config ARCH_MEMORY_PROBE 1571 bool "Enable sysfs memory/probe interface" 1572 depends on MEMORY_HOTPLUG 1573 help 1574 This option enables a sysfs memory/probe interface for testing. 1575 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1576 If you are unsure how to answer this question, answer N. 1577 1578config ARCH_PROC_KCORE_TEXT 1579 def_bool y 1580 depends on X86_64 && PROC_KCORE 1581 1582config ILLEGAL_POINTER_VALUE 1583 hex 1584 default 0 if X86_32 1585 default 0xdead000000000000 if X86_64 1586 1587config X86_PMEM_LEGACY_DEVICE 1588 bool 1589 1590config X86_PMEM_LEGACY 1591 tristate "Support non-standard NVDIMMs and ADR protected memory" 1592 depends on PHYS_ADDR_T_64BIT 1593 depends on BLK_DEV 1594 select X86_PMEM_LEGACY_DEVICE 1595 select NUMA_KEEP_MEMINFO if NUMA 1596 select LIBNVDIMM 1597 help 1598 Treat memory marked using the non-standard e820 type of 12 as used 1599 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1600 The kernel will offer these regions to the 'pmem' driver so 1601 they can be used for persistent storage. 1602 1603 Say Y if unsure. 1604 1605config X86_CHECK_BIOS_CORRUPTION 1606 bool "Check for low memory corruption" 1607 help 1608 Periodically check for memory corruption in low memory, which 1609 is suspected to be caused by BIOS. Even when enabled in the 1610 configuration, it is disabled at runtime. Enable it by 1611 setting "memory_corruption_check=1" on the kernel command 1612 line. By default it scans the low 64k of memory every 60 1613 seconds; see the memory_corruption_check_size and 1614 memory_corruption_check_period parameters in 1615 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1616 1617 When enabled with the default parameters, this option has 1618 almost no overhead, as it reserves a relatively small amount 1619 of memory and scans it infrequently. It both detects corruption 1620 and prevents it from affecting the running system. 1621 1622 It is, however, intended as a diagnostic tool; if repeatable 1623 BIOS-originated corruption always affects the same memory, 1624 you can use memmap= to prevent the kernel from using that 1625 memory. 1626 1627config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1628 bool "Set the default setting of memory_corruption_check" 1629 depends on X86_CHECK_BIOS_CORRUPTION 1630 default y 1631 help 1632 Set whether the default state of memory_corruption_check is 1633 on or off. 1634 1635config MATH_EMULATION 1636 bool 1637 depends on MODIFY_LDT_SYSCALL 1638 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1639 help 1640 Linux can emulate a math coprocessor (used for floating point 1641 operations) if you don't have one. 486DX and Pentium processors have 1642 a math coprocessor built in, 486SX and 386 do not, unless you added 1643 a 487DX or 387, respectively. (The messages during boot time can 1644 give you some hints here ["man dmesg"].) Everyone needs either a 1645 coprocessor or this emulation. 1646 1647 If you don't have a math coprocessor, you need to say Y here; if you 1648 say Y here even though you have a coprocessor, the coprocessor will 1649 be used nevertheless. (This behavior can be changed with the kernel 1650 command line option "no387", which comes handy if your coprocessor 1651 is broken. Try "man bootparam" or see the documentation of your boot 1652 loader (lilo or loadlin) about how to pass options to the kernel at 1653 boot time.) This means that it is a good idea to say Y here if you 1654 intend to use this kernel on different machines. 1655 1656 More information about the internals of the Linux math coprocessor 1657 emulation can be found in <file:arch/x86/math-emu/README>. 1658 1659 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1660 kernel, it won't hurt. 1661 1662config MTRR 1663 def_bool y 1664 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1665 help 1666 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1667 the Memory Type Range Registers (MTRRs) may be used to control 1668 processor access to memory ranges. This is most useful if you have 1669 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1670 allows bus write transfers to be combined into a larger transfer 1671 before bursting over the PCI/AGP bus. This can increase performance 1672 of image write operations 2.5 times or more. Saying Y here creates a 1673 /proc/mtrr file which may be used to manipulate your processor's 1674 MTRRs. Typically the X server should use this. 1675 1676 This code has a reasonably generic interface so that similar 1677 control registers on other processors can be easily supported 1678 as well: 1679 1680 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1681 Registers (ARRs) which provide a similar functionality to MTRRs. For 1682 these, the ARRs are used to emulate the MTRRs. 1683 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1684 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1685 write-combining. All of these processors are supported by this code 1686 and it makes sense to say Y here if you have one of them. 1687 1688 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1689 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1690 can lead to all sorts of problems, so it's good to say Y here. 1691 1692 You can safely say Y even if your machine doesn't have MTRRs, you'll 1693 just add about 9 KB to your kernel. 1694 1695 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1696 1697config MTRR_SANITIZER 1698 def_bool y 1699 prompt "MTRR cleanup support" 1700 depends on MTRR 1701 help 1702 Convert MTRR layout from continuous to discrete, so X drivers can 1703 add writeback entries. 1704 1705 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1706 The largest mtrr entry size for a continuous block can be set with 1707 mtrr_chunk_size. 1708 1709 If unsure, say Y. 1710 1711config MTRR_SANITIZER_ENABLE_DEFAULT 1712 int "MTRR cleanup enable value (0-1)" 1713 range 0 1 1714 default "0" 1715 depends on MTRR_SANITIZER 1716 help 1717 Enable mtrr cleanup default value 1718 1719config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1720 int "MTRR cleanup spare reg num (0-7)" 1721 range 0 7 1722 default "1" 1723 depends on MTRR_SANITIZER 1724 help 1725 mtrr cleanup spare entries default, it can be changed via 1726 mtrr_spare_reg_nr=N on the kernel command line. 1727 1728config X86_PAT 1729 def_bool y 1730 prompt "x86 PAT support" if EXPERT 1731 depends on MTRR 1732 select ARCH_USES_PG_ARCH_2 1733 help 1734 Use PAT attributes to setup page level cache control. 1735 1736 PATs are the modern equivalents of MTRRs and are much more 1737 flexible than MTRRs. 1738 1739 Say N here if you see bootup problems (boot crash, boot hang, 1740 spontaneous reboots) or a non-working video driver. 1741 1742 If unsure, say Y. 1743 1744config X86_UMIP 1745 def_bool y 1746 prompt "User Mode Instruction Prevention" if EXPERT 1747 help 1748 User Mode Instruction Prevention (UMIP) is a security feature in 1749 some x86 processors. If enabled, a general protection fault is 1750 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1751 executed in user mode. These instructions unnecessarily expose 1752 information about the hardware state. 1753 1754 The vast majority of applications do not use these instructions. 1755 For the very few that do, software emulation is provided in 1756 specific cases in protected and virtual-8086 modes. Emulated 1757 results are dummy. 1758 1759config CC_HAS_IBT 1760 # GCC >= 9 and binutils >= 2.29 1761 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1762 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || CC_IS_CLANG) && \ 1763 $(as-instr,endbr64) 1764 1765config X86_CET 1766 def_bool n 1767 help 1768 CET features configured (Shadow stack or IBT) 1769 1770config X86_KERNEL_IBT 1771 prompt "Indirect Branch Tracking" 1772 def_bool y 1773 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1774 select OBJTOOL 1775 select X86_CET 1776 help 1777 Build the kernel with support for Indirect Branch Tracking, a 1778 hardware support course-grain forward-edge Control Flow Integrity 1779 protection. It enforces that all indirect calls must land on 1780 an ENDBR instruction, as such, the compiler will instrument the 1781 code with them to make this happen. 1782 1783 In addition to building the kernel with IBT, seal all functions that 1784 are not indirect call targets, avoiding them ever becoming one. 1785 1786 This requires LTO like objtool runs and will slow down the build. It 1787 does significantly reduce the number of ENDBR instructions in the 1788 kernel image. 1789 1790config X86_INTEL_MEMORY_PROTECTION_KEYS 1791 prompt "Memory Protection Keys" 1792 def_bool y 1793 # Note: only available in 64-bit mode 1794 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1795 select ARCH_USES_HIGH_VMA_FLAGS 1796 select ARCH_HAS_PKEYS 1797 help 1798 Memory Protection Keys provides a mechanism for enforcing 1799 page-based protections, but without requiring modification of the 1800 page tables when an application changes protection domains. 1801 1802 For details, see Documentation/core-api/protection-keys.rst 1803 1804 If unsure, say y. 1805 1806config ARCH_PKEY_BITS 1807 int 1808 default 4 1809 1810choice 1811 prompt "TSX enable mode" 1812 depends on CPU_SUP_INTEL 1813 default X86_INTEL_TSX_MODE_OFF 1814 help 1815 Intel's TSX (Transactional Synchronization Extensions) feature 1816 allows to optimize locking protocols through lock elision which 1817 can lead to a noticeable performance boost. 1818 1819 On the other hand it has been shown that TSX can be exploited 1820 to form side channel attacks (e.g. TAA) and chances are there 1821 will be more of those attacks discovered in the future. 1822 1823 Therefore TSX is not enabled by default (aka tsx=off). An admin 1824 might override this decision by tsx=on the command line parameter. 1825 Even with TSX enabled, the kernel will attempt to enable the best 1826 possible TAA mitigation setting depending on the microcode available 1827 for the particular machine. 1828 1829 This option allows to set the default tsx mode between tsx=on, =off 1830 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1831 details. 1832 1833 Say off if not sure, auto if TSX is in use but it should be used on safe 1834 platforms or on if TSX is in use and the security aspect of tsx is not 1835 relevant. 1836 1837config X86_INTEL_TSX_MODE_OFF 1838 bool "off" 1839 help 1840 TSX is disabled if possible - equals to tsx=off command line parameter. 1841 1842config X86_INTEL_TSX_MODE_ON 1843 bool "on" 1844 help 1845 TSX is always enabled on TSX capable HW - equals the tsx=on command 1846 line parameter. 1847 1848config X86_INTEL_TSX_MODE_AUTO 1849 bool "auto" 1850 help 1851 TSX is enabled on TSX capable HW that is believed to be safe against 1852 side channel attacks- equals the tsx=auto command line parameter. 1853endchoice 1854 1855config X86_SGX 1856 bool "Software Guard eXtensions (SGX)" 1857 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1858 select CRYPTO_LIB_SHA256 1859 select MMU_NOTIFIER 1860 select NUMA_KEEP_MEMINFO if NUMA 1861 select XARRAY_MULTI 1862 help 1863 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1864 that can be used by applications to set aside private regions of code 1865 and data, referred to as enclaves. An enclave's private memory can 1866 only be accessed by code running within the enclave. Accesses from 1867 outside the enclave, including other enclaves, are disallowed by 1868 hardware. 1869 1870 If unsure, say N. 1871 1872config X86_USER_SHADOW_STACK 1873 bool "X86 userspace shadow stack" 1874 depends on AS_WRUSS 1875 depends on X86_64 1876 select ARCH_USES_HIGH_VMA_FLAGS 1877 select ARCH_HAS_USER_SHADOW_STACK 1878 select X86_CET 1879 help 1880 Shadow stack protection is a hardware feature that detects function 1881 return address corruption. This helps mitigate ROP attacks. 1882 Applications must be enabled to use it, and old userspace does not 1883 get protection "for free". 1884 1885 CPUs supporting shadow stacks were first released in 2020. 1886 1887 See Documentation/arch/x86/shstk.rst for more information. 1888 1889 If unsure, say N. 1890 1891config INTEL_TDX_HOST 1892 bool "Intel Trust Domain Extensions (TDX) host support" 1893 depends on CPU_SUP_INTEL 1894 depends on X86_64 1895 depends on KVM_INTEL 1896 depends on X86_X2APIC 1897 select ARCH_KEEP_MEMBLOCK 1898 depends on CONTIG_ALLOC 1899 depends on X86_MCE 1900 help 1901 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1902 host and certain physical attacks. This option enables necessary TDX 1903 support in the host kernel to run confidential VMs. 1904 1905 If unsure, say N. 1906 1907config EFI 1908 bool "EFI runtime service support" 1909 depends on ACPI 1910 select UCS2_STRING 1911 select EFI_RUNTIME_WRAPPERS 1912 select ARCH_USE_MEMREMAP_PROT 1913 select EFI_RUNTIME_MAP if KEXEC_CORE 1914 help 1915 This enables the kernel to use EFI runtime services that are 1916 available (such as the EFI variable services). 1917 1918 This option is only useful on systems that have EFI firmware. 1919 In addition, you should use the latest ELILO loader available 1920 at <http://elilo.sourceforge.net> in order to take advantage 1921 of EFI runtime services. However, even with this option, the 1922 resultant kernel should continue to boot on existing non-EFI 1923 platforms. 1924 1925config EFI_STUB 1926 bool "EFI stub support" 1927 depends on EFI 1928 select RELOCATABLE 1929 help 1930 This kernel feature allows a bzImage to be loaded directly 1931 by EFI firmware without the use of a bootloader. 1932 1933 See Documentation/admin-guide/efi-stub.rst for more information. 1934 1935config EFI_HANDOVER_PROTOCOL 1936 bool "EFI handover protocol (DEPRECATED)" 1937 depends on EFI_STUB 1938 default y 1939 help 1940 Select this in order to include support for the deprecated EFI 1941 handover protocol, which defines alternative entry points into the 1942 EFI stub. This is a practice that has no basis in the UEFI 1943 specification, and requires a priori knowledge on the part of the 1944 bootloader about Linux/x86 specific ways of passing the command line 1945 and initrd, and where in memory those assets may be loaded. 1946 1947 If in doubt, say Y. Even though the corresponding support is not 1948 present in upstream GRUB or other bootloaders, most distros build 1949 GRUB with numerous downstream patches applied, and may rely on the 1950 handover protocol as as result. 1951 1952config EFI_MIXED 1953 bool "EFI mixed-mode support" 1954 depends on EFI_STUB && X86_64 1955 help 1956 Enabling this feature allows a 64-bit kernel to be booted 1957 on a 32-bit firmware, provided that your CPU supports 64-bit 1958 mode. 1959 1960 Note that it is not possible to boot a mixed-mode enabled 1961 kernel via the EFI boot stub - a bootloader that supports 1962 the EFI handover protocol must be used. 1963 1964 If unsure, say N. 1965 1966config EFI_RUNTIME_MAP 1967 bool "Export EFI runtime maps to sysfs" if EXPERT 1968 depends on EFI 1969 help 1970 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 1971 That memory map is required by the 2nd kernel to set up EFI virtual 1972 mappings after kexec, but can also be used for debugging purposes. 1973 1974 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 1975 1976source "kernel/Kconfig.hz" 1977 1978config ARCH_SUPPORTS_KEXEC 1979 def_bool y 1980 1981config ARCH_SUPPORTS_KEXEC_FILE 1982 def_bool X86_64 1983 1984config ARCH_SELECTS_KEXEC_FILE 1985 def_bool y 1986 depends on KEXEC_FILE 1987 select HAVE_IMA_KEXEC if IMA 1988 1989config ARCH_SUPPORTS_KEXEC_PURGATORY 1990 def_bool y 1991 1992config ARCH_SUPPORTS_KEXEC_SIG 1993 def_bool y 1994 1995config ARCH_SUPPORTS_KEXEC_SIG_FORCE 1996 def_bool y 1997 1998config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 1999 def_bool y 2000 2001config ARCH_SUPPORTS_KEXEC_JUMP 2002 def_bool y 2003 2004config ARCH_SUPPORTS_KEXEC_HANDOVER 2005 def_bool X86_64 2006 2007config ARCH_SUPPORTS_CRASH_DUMP 2008 def_bool X86_64 || (X86_32 && HIGHMEM) 2009 2010config ARCH_DEFAULT_CRASH_DUMP 2011 def_bool y 2012 2013config ARCH_SUPPORTS_CRASH_HOTPLUG 2014 def_bool y 2015 2016config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2017 def_bool CRASH_RESERVE 2018 2019config PHYSICAL_START 2020 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2021 default "0x1000000" 2022 help 2023 This gives the physical address where the kernel is loaded. 2024 2025 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2026 will decompress itself to above physical address and run from there. 2027 Otherwise, bzImage will run from the address where it has been loaded 2028 by the boot loader. The only exception is if it is loaded below the 2029 above physical address, in which case it will relocate itself there. 2030 2031 In normal kdump cases one does not have to set/change this option 2032 as now bzImage can be compiled as a completely relocatable image 2033 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2034 address. This option is mainly useful for the folks who don't want 2035 to use a bzImage for capturing the crash dump and want to use a 2036 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2037 to be specifically compiled to run from a specific memory area 2038 (normally a reserved region) and this option comes handy. 2039 2040 So if you are using bzImage for capturing the crash dump, 2041 leave the value here unchanged to 0x1000000 and set 2042 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2043 for capturing the crash dump change this value to start of 2044 the reserved region. In other words, it can be set based on 2045 the "X" value as specified in the "crashkernel=YM@XM" 2046 command line boot parameter passed to the panic-ed 2047 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2048 for more details about crash dumps. 2049 2050 Usage of bzImage for capturing the crash dump is recommended as 2051 one does not have to build two kernels. Same kernel can be used 2052 as production kernel and capture kernel. Above option should have 2053 gone away after relocatable bzImage support is introduced. But it 2054 is present because there are users out there who continue to use 2055 vmlinux for dump capture. This option should go away down the 2056 line. 2057 2058 Don't change this unless you know what you are doing. 2059 2060config RELOCATABLE 2061 bool "Build a relocatable kernel" 2062 default y 2063 help 2064 This builds a kernel image that retains relocation information 2065 so it can be loaded someplace besides the default 1MB. 2066 The relocations tend to make the kernel binary about 10% larger, 2067 but are discarded at runtime. 2068 2069 One use is for the kexec on panic case where the recovery kernel 2070 must live at a different physical address than the primary 2071 kernel. 2072 2073 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2074 it has been loaded at and the compile time physical address 2075 (CONFIG_PHYSICAL_START) is used as the minimum location. 2076 2077config RANDOMIZE_BASE 2078 bool "Randomize the address of the kernel image (KASLR)" 2079 depends on RELOCATABLE 2080 default y 2081 help 2082 In support of Kernel Address Space Layout Randomization (KASLR), 2083 this randomizes the physical address at which the kernel image 2084 is decompressed and the virtual address where the kernel 2085 image is mapped, as a security feature that deters exploit 2086 attempts relying on knowledge of the location of kernel 2087 code internals. 2088 2089 On 64-bit, the kernel physical and virtual addresses are 2090 randomized separately. The physical address will be anywhere 2091 between 16MB and the top of physical memory (up to 64TB). The 2092 virtual address will be randomized from 16MB up to 1GB (9 bits 2093 of entropy). Note that this also reduces the memory space 2094 available to kernel modules from 1.5GB to 1GB. 2095 2096 On 32-bit, the kernel physical and virtual addresses are 2097 randomized together. They will be randomized from 16MB up to 2098 512MB (8 bits of entropy). 2099 2100 Entropy is generated using the RDRAND instruction if it is 2101 supported. If RDTSC is supported, its value is mixed into 2102 the entropy pool as well. If neither RDRAND nor RDTSC are 2103 supported, then entropy is read from the i8254 timer. The 2104 usable entropy is limited by the kernel being built using 2105 2GB addressing, and that PHYSICAL_ALIGN must be at a 2106 minimum of 2MB. As a result, only 10 bits of entropy are 2107 theoretically possible, but the implementations are further 2108 limited due to memory layouts. 2109 2110 If unsure, say Y. 2111 2112# Relocation on x86 needs some additional build support 2113config X86_NEED_RELOCS 2114 def_bool y 2115 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2116 select ARCH_VMLINUX_NEEDS_RELOCS 2117 2118config PHYSICAL_ALIGN 2119 hex "Alignment value to which kernel should be aligned" 2120 default "0x200000" 2121 range 0x2000 0x1000000 if X86_32 2122 range 0x200000 0x1000000 if X86_64 2123 help 2124 This value puts the alignment restrictions on physical address 2125 where kernel is loaded and run from. Kernel is compiled for an 2126 address which meets above alignment restriction. 2127 2128 If bootloader loads the kernel at a non-aligned address and 2129 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2130 address aligned to above value and run from there. 2131 2132 If bootloader loads the kernel at a non-aligned address and 2133 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2134 load address and decompress itself to the address it has been 2135 compiled for and run from there. The address for which kernel is 2136 compiled already meets above alignment restrictions. Hence the 2137 end result is that kernel runs from a physical address meeting 2138 above alignment restrictions. 2139 2140 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2141 this value must be a multiple of 0x200000. 2142 2143 Don't change this unless you know what you are doing. 2144 2145config RANDOMIZE_MEMORY 2146 bool "Randomize the kernel memory sections" 2147 depends on X86_64 2148 depends on RANDOMIZE_BASE 2149 default RANDOMIZE_BASE 2150 help 2151 Randomizes the base virtual address of kernel memory sections 2152 (physical memory mapping, vmalloc & vmemmap). This security feature 2153 makes exploits relying on predictable memory locations less reliable. 2154 2155 The order of allocations remains unchanged. Entropy is generated in 2156 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2157 configuration have in average 30,000 different possible virtual 2158 addresses for each memory section. 2159 2160 If unsure, say Y. 2161 2162config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2163 hex "Physical memory mapping padding" if EXPERT 2164 depends on RANDOMIZE_MEMORY 2165 default "0xa" if MEMORY_HOTPLUG 2166 default "0x0" 2167 range 0x1 0x40 if MEMORY_HOTPLUG 2168 range 0x0 0x40 2169 help 2170 Define the padding in terabytes added to the existing physical 2171 memory size during kernel memory randomization. It is useful 2172 for memory hotplug support but reduces the entropy available for 2173 address randomization. 2174 2175 If unsure, leave at the default value. 2176 2177config ADDRESS_MASKING 2178 bool "Linear Address Masking support" 2179 depends on X86_64 2180 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2181 help 2182 Linear Address Masking (LAM) modifies the checking that is applied 2183 to 64-bit linear addresses, allowing software to use of the 2184 untranslated address bits for metadata. 2185 2186 The capability can be used for efficient address sanitizers (ASAN) 2187 implementation and for optimizations in JITs. 2188 2189config HOTPLUG_CPU 2190 def_bool y 2191 depends on SMP 2192 2193config COMPAT_VDSO 2194 def_bool n 2195 prompt "Workaround for glibc 2.3.2 / 2.3.3 (released in year 2003/2004)" 2196 depends on COMPAT_32 2197 help 2198 Certain buggy versions of glibc will crash if they are 2199 presented with a 32-bit vDSO that is not mapped at the address 2200 indicated in its segment table. 2201 2202 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2203 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2204 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2205 the only released version with the bug, but OpenSUSE 9 2206 contains a buggy "glibc 2.3.2". 2207 2208 The symptom of the bug is that everything crashes on startup, saying: 2209 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2210 2211 Saying Y here changes the default value of the vdso32 boot 2212 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2213 This works around the glibc bug but hurts performance. 2214 2215 If unsure, say N: if you are compiling your own kernel, you 2216 are unlikely to be using a buggy version of glibc. 2217 2218choice 2219 prompt "vsyscall table for legacy applications" 2220 depends on X86_64 2221 default LEGACY_VSYSCALL_XONLY 2222 help 2223 Legacy user code that does not know how to find the vDSO expects 2224 to be able to issue three syscalls by calling fixed addresses in 2225 kernel space. Since this location is not randomized with ASLR, 2226 it can be used to assist security vulnerability exploitation. 2227 2228 This setting can be changed at boot time via the kernel command 2229 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2230 is deprecated and can only be enabled using the kernel command 2231 line. 2232 2233 On a system with recent enough glibc (2.14 or newer) and no 2234 static binaries, you can say None without a performance penalty 2235 to improve security. 2236 2237 If unsure, select "Emulate execution only". 2238 2239 config LEGACY_VSYSCALL_XONLY 2240 bool "Emulate execution only" 2241 help 2242 The kernel traps and emulates calls into the fixed vsyscall 2243 address mapping and does not allow reads. This 2244 configuration is recommended when userspace might use the 2245 legacy vsyscall area but support for legacy binary 2246 instrumentation of legacy code is not needed. It mitigates 2247 certain uses of the vsyscall area as an ASLR-bypassing 2248 buffer. 2249 2250 config LEGACY_VSYSCALL_NONE 2251 bool "None" 2252 help 2253 There will be no vsyscall mapping at all. This will 2254 eliminate any risk of ASLR bypass due to the vsyscall 2255 fixed address mapping. Attempts to use the vsyscalls 2256 will be reported to dmesg, so that either old or 2257 malicious userspace programs can be identified. 2258 2259endchoice 2260 2261config CMDLINE_BOOL 2262 bool "Built-in kernel command line" 2263 help 2264 Allow for specifying boot arguments to the kernel at 2265 build time. On some systems (e.g. embedded ones), it is 2266 necessary or convenient to provide some or all of the 2267 kernel boot arguments with the kernel itself (that is, 2268 to not rely on the boot loader to provide them.) 2269 2270 To compile command line arguments into the kernel, 2271 set this option to 'Y', then fill in the 2272 boot arguments in CONFIG_CMDLINE. 2273 2274 Systems with fully functional boot loaders (i.e. non-embedded) 2275 should leave this option set to 'N'. 2276 2277config CMDLINE 2278 string "Built-in kernel command string" 2279 depends on CMDLINE_BOOL 2280 default "" 2281 help 2282 Enter arguments here that should be compiled into the kernel 2283 image and used at boot time. If the boot loader provides a 2284 command line at boot time, it is appended to this string to 2285 form the full kernel command line, when the system boots. 2286 2287 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2288 change this behavior. 2289 2290 In most cases, the command line (whether built-in or provided 2291 by the boot loader) should specify the device for the root 2292 file system. 2293 2294config CMDLINE_OVERRIDE 2295 bool "Built-in command line overrides boot loader arguments" 2296 depends on CMDLINE_BOOL && CMDLINE != "" 2297 help 2298 Set this option to 'Y' to have the kernel ignore the boot loader 2299 command line, and use ONLY the built-in command line. 2300 2301 This is used to work around broken boot loaders. This should 2302 be set to 'N' under normal conditions. 2303 2304config MODIFY_LDT_SYSCALL 2305 bool "Enable the LDT (local descriptor table)" if EXPERT 2306 default y 2307 help 2308 Linux can allow user programs to install a per-process x86 2309 Local Descriptor Table (LDT) using the modify_ldt(2) system 2310 call. This is required to run 16-bit or segmented code such as 2311 DOSEMU or some Wine programs. It is also used by some very old 2312 threading libraries. 2313 2314 Enabling this feature adds a small amount of overhead to 2315 context switches and increases the low-level kernel attack 2316 surface. Disabling it removes the modify_ldt(2) system call. 2317 2318 Saying 'N' here may make sense for embedded or server kernels. 2319 2320config STRICT_SIGALTSTACK_SIZE 2321 bool "Enforce strict size checking for sigaltstack" 2322 depends on DYNAMIC_SIGFRAME 2323 help 2324 For historical reasons MINSIGSTKSZ is a constant which became 2325 already too small with AVX512 support. Add a mechanism to 2326 enforce strict checking of the sigaltstack size against the 2327 real size of the FPU frame. This option enables the check 2328 by default. It can also be controlled via the kernel command 2329 line option 'strict_sas_size' independent of this config 2330 switch. Enabling it might break existing applications which 2331 allocate a too small sigaltstack but 'work' because they 2332 never get a signal delivered. 2333 2334 Say 'N' unless you want to really enforce this check. 2335 2336config CFI_AUTO_DEFAULT 2337 bool "Attempt to use FineIBT by default at boot time" 2338 depends on FINEIBT 2339 depends on !RUST || RUSTC_VERSION >= 108800 2340 default y 2341 help 2342 Attempt to use FineIBT by default at boot time. If enabled, 2343 this is the same as booting with "cfi=auto". If disabled, 2344 this is the same as booting with "cfi=kcfi". 2345 2346source "kernel/livepatch/Kconfig" 2347 2348config X86_BUS_LOCK_DETECT 2349 bool "Split Lock Detect and Bus Lock Detect support" 2350 depends on CPU_SUP_INTEL || CPU_SUP_AMD 2351 default y 2352 help 2353 Enable Split Lock Detect and Bus Lock Detect functionalities. 2354 See <file:Documentation/arch/x86/buslock.rst> for more information. 2355 2356endmenu 2357 2358config CC_HAS_NAMED_AS 2359 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null) 2360 depends on CC_IS_GCC 2361 2362# 2363# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN) 2364# are incompatible with named address spaces with GCC < 13.3 2365# (see GCC PR sanitizer/111736 and also PR sanitizer/115172). 2366# 2367 2368config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2369 def_bool y 2370 depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300 2371 depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200 2372 2373config USE_X86_SEG_SUPPORT 2374 def_bool CC_HAS_NAMED_AS 2375 depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS 2376 2377config CC_HAS_SLS 2378 def_bool $(cc-option,-mharden-sls=all) 2379 2380config CC_HAS_RETURN_THUNK 2381 def_bool $(cc-option,-mfunction-return=thunk-extern) 2382 2383config CC_HAS_ENTRY_PADDING 2384 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2385 2386config CC_HAS_KCFI_ARITY 2387 def_bool $(cc-option,-fsanitize=kcfi -fsanitize-kcfi-arity) 2388 depends on CC_IS_CLANG && !RUST 2389 2390config FUNCTION_PADDING_CFI 2391 int 2392 default 59 if FUNCTION_ALIGNMENT_64B 2393 default 27 if FUNCTION_ALIGNMENT_32B 2394 default 11 if FUNCTION_ALIGNMENT_16B 2395 default 3 if FUNCTION_ALIGNMENT_8B 2396 default 0 2397 2398# Basically: FUNCTION_ALIGNMENT - 5*CFI 2399# except Kconfig can't do arithmetic :/ 2400config FUNCTION_PADDING_BYTES 2401 int 2402 default FUNCTION_PADDING_CFI if CFI 2403 default FUNCTION_ALIGNMENT 2404 2405config CALL_PADDING 2406 def_bool n 2407 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2408 select FUNCTION_ALIGNMENT_16B 2409 2410config FINEIBT 2411 def_bool y 2412 depends on X86_KERNEL_IBT && CFI && MITIGATION_RETPOLINE 2413 select CALL_PADDING 2414 2415config FINEIBT_BHI 2416 def_bool y 2417 depends on FINEIBT && CC_HAS_KCFI_ARITY 2418 2419config HAVE_CALL_THUNKS 2420 def_bool y 2421 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2422 2423config CALL_THUNKS 2424 def_bool n 2425 select CALL_PADDING 2426 2427config PREFIX_SYMBOLS 2428 def_bool y 2429 depends on CALL_PADDING && !CFI 2430 2431menuconfig CPU_MITIGATIONS 2432 bool "Mitigations for CPU vulnerabilities" 2433 default y 2434 help 2435 Say Y here to enable options which enable mitigations for hardware 2436 vulnerabilities (usually related to speculative execution). 2437 Mitigations can be disabled or restricted to SMT systems at runtime 2438 via the "mitigations" kernel parameter. 2439 2440 If you say N, all mitigations will be disabled. This CANNOT be 2441 overridden at runtime. 2442 2443 Say 'Y', unless you really know what you are doing. 2444 2445if CPU_MITIGATIONS 2446 2447config MITIGATION_PAGE_TABLE_ISOLATION 2448 bool "Remove the kernel mapping in user mode" 2449 default y 2450 depends on (X86_64 || X86_PAE) 2451 help 2452 This feature reduces the number of hardware side channels by 2453 ensuring that the majority of kernel addresses are not mapped 2454 into userspace. 2455 2456 See Documentation/arch/x86/pti.rst for more details. 2457 2458config MITIGATION_RETPOLINE 2459 bool "Avoid speculative indirect branches in kernel" 2460 select OBJTOOL if HAVE_OBJTOOL 2461 default y 2462 help 2463 Compile kernel with the retpoline compiler options to guard against 2464 kernel-to-user data leaks by avoiding speculative indirect 2465 branches. Requires a compiler with -mindirect-branch=thunk-extern 2466 support for full protection. The kernel may run slower. 2467 2468config MITIGATION_RETHUNK 2469 bool "Enable return-thunks" 2470 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2471 select OBJTOOL if HAVE_OBJTOOL 2472 default y if X86_64 2473 help 2474 Compile the kernel with the return-thunks compiler option to guard 2475 against kernel-to-user data leaks by avoiding return speculation. 2476 Requires a compiler with -mfunction-return=thunk-extern 2477 support for full protection. The kernel may run slower. 2478 2479config MITIGATION_UNRET_ENTRY 2480 bool "Enable UNRET on kernel entry" 2481 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2482 default y 2483 help 2484 Compile the kernel with support for the retbleed=unret mitigation. 2485 2486config MITIGATION_CALL_DEPTH_TRACKING 2487 bool "Mitigate RSB underflow with call depth tracking" 2488 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2489 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2490 select CALL_THUNKS 2491 default y 2492 help 2493 Compile the kernel with call depth tracking to mitigate the Intel 2494 SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off 2495 by default and needs to be enabled on the kernel command line via the 2496 retbleed=stuff option. For non-affected systems the overhead of this 2497 option is marginal as the call depth tracking is using run-time 2498 generated call thunks in a compiler generated padding area and call 2499 patching. This increases text size by ~5%. For non affected systems 2500 this space is unused. On affected SKL systems this results in a 2501 significant performance gain over the IBRS mitigation. 2502 2503config CALL_THUNKS_DEBUG 2504 bool "Enable call thunks and call depth tracking debugging" 2505 depends on MITIGATION_CALL_DEPTH_TRACKING 2506 select FUNCTION_ALIGNMENT_32B 2507 default n 2508 help 2509 Enable call/ret counters for imbalance detection and build in 2510 a noisy dmesg about callthunks generation and call patching for 2511 trouble shooting. The debug prints need to be enabled on the 2512 kernel command line with 'debug-callthunks'. 2513 Only enable this when you are debugging call thunks as this 2514 creates a noticeable runtime overhead. If unsure say N. 2515 2516config MITIGATION_IBPB_ENTRY 2517 bool "Enable IBPB on kernel entry" 2518 depends on CPU_SUP_AMD && X86_64 2519 default y 2520 help 2521 Compile the kernel with support for the retbleed=ibpb and 2522 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations. 2523 2524config MITIGATION_IBRS_ENTRY 2525 bool "Enable IBRS on kernel entry" 2526 depends on CPU_SUP_INTEL && X86_64 2527 default y 2528 help 2529 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2530 This mitigates both spectre_v2 and retbleed at great cost to 2531 performance. 2532 2533config MITIGATION_SRSO 2534 bool "Mitigate speculative RAS overflow on AMD" 2535 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2536 default y 2537 help 2538 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2539 2540config MITIGATION_SLS 2541 bool "Mitigate Straight-Line-Speculation" 2542 depends on CC_HAS_SLS && X86_64 2543 select OBJTOOL if HAVE_OBJTOOL 2544 default n 2545 help 2546 Compile the kernel with straight-line-speculation options to guard 2547 against straight line speculation. The kernel image might be slightly 2548 larger. 2549 2550config MITIGATION_GDS 2551 bool "Mitigate Gather Data Sampling" 2552 depends on CPU_SUP_INTEL 2553 default y 2554 help 2555 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware 2556 vulnerability which allows unprivileged speculative access to data 2557 which was previously stored in vector registers. The attacker uses gather 2558 instructions to infer the stale vector register data. 2559 2560config MITIGATION_RFDS 2561 bool "RFDS Mitigation" 2562 depends on CPU_SUP_INTEL 2563 default y 2564 help 2565 Enable mitigation for Register File Data Sampling (RFDS) by default. 2566 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2567 allows unprivileged speculative access to stale data previously 2568 stored in floating point, vector and integer registers. 2569 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2570 2571config MITIGATION_SPECTRE_BHI 2572 bool "Mitigate Spectre-BHB (Branch History Injection)" 2573 depends on CPU_SUP_INTEL 2574 default y 2575 help 2576 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2577 where the branch history buffer is poisoned to speculatively steer 2578 indirect branches. 2579 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2580 2581config MITIGATION_MDS 2582 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug" 2583 depends on CPU_SUP_INTEL 2584 default y 2585 help 2586 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is 2587 a hardware vulnerability which allows unprivileged speculative access 2588 to data which is available in various CPU internal buffers. 2589 See also <file:Documentation/admin-guide/hw-vuln/mds.rst> 2590 2591config MITIGATION_TAA 2592 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug" 2593 depends on CPU_SUP_INTEL 2594 default y 2595 help 2596 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware 2597 vulnerability that allows unprivileged speculative access to data 2598 which is available in various CPU internal buffers by using 2599 asynchronous aborts within an Intel TSX transactional region. 2600 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst> 2601 2602config MITIGATION_MMIO_STALE_DATA 2603 bool "Mitigate MMIO Stale Data hardware bug" 2604 depends on CPU_SUP_INTEL 2605 default y 2606 help 2607 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO 2608 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO) 2609 vulnerabilities that can expose data. The vulnerabilities require the 2610 attacker to have access to MMIO. 2611 See also 2612 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst> 2613 2614config MITIGATION_L1TF 2615 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug" 2616 depends on CPU_SUP_INTEL 2617 default y 2618 help 2619 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a 2620 hardware vulnerability which allows unprivileged speculative access to data 2621 available in the Level 1 Data Cache. 2622 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst 2623 2624config MITIGATION_RETBLEED 2625 bool "Mitigate RETBleed hardware bug" 2626 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY 2627 default y 2628 help 2629 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution 2630 with Return Instructions) vulnerability. RETBleed is a speculative 2631 execution attack which takes advantage of microarchitectural behavior 2632 in many modern microprocessors, similar to Spectre v2. An 2633 unprivileged attacker can use these flaws to bypass conventional 2634 memory security restrictions to gain read access to privileged memory 2635 that would otherwise be inaccessible. 2636 2637config MITIGATION_SPECTRE_V1 2638 bool "Mitigate SPECTRE V1 hardware bug" 2639 default y 2640 help 2641 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a 2642 class of side channel attacks that takes advantage of speculative 2643 execution that bypasses conditional branch instructions used for 2644 memory access bounds check. 2645 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2646 2647config MITIGATION_SPECTRE_V2 2648 bool "Mitigate SPECTRE V2 hardware bug" 2649 default y 2650 help 2651 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre 2652 V2 is a class of side channel attacks that takes advantage of 2653 indirect branch predictors inside the processor. In Spectre variant 2 2654 attacks, the attacker can steer speculative indirect branches in the 2655 victim to gadget code by poisoning the branch target buffer of a CPU 2656 used for predicting indirect branch addresses. 2657 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2658 2659config MITIGATION_SRBDS 2660 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug" 2661 depends on CPU_SUP_INTEL 2662 default y 2663 help 2664 Enable mitigation for Special Register Buffer Data Sampling (SRBDS). 2665 SRBDS is a hardware vulnerability that allows Microarchitectural Data 2666 Sampling (MDS) techniques to infer values returned from special 2667 register accesses. An unprivileged user can extract values returned 2668 from RDRAND and RDSEED executed on another core or sibling thread 2669 using MDS techniques. 2670 See also 2671 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst> 2672 2673config MITIGATION_SSB 2674 bool "Mitigate Speculative Store Bypass (SSB) hardware bug" 2675 default y 2676 help 2677 Enable mitigation for Speculative Store Bypass (SSB). SSB is a 2678 hardware security vulnerability and its exploitation takes advantage 2679 of speculative execution in a similar way to the Meltdown and Spectre 2680 security vulnerabilities. 2681 2682config MITIGATION_ITS 2683 bool "Enable Indirect Target Selection mitigation" 2684 depends on CPU_SUP_INTEL && X86_64 2685 depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK 2686 select EXECMEM 2687 default y 2688 help 2689 Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in 2690 BPU on some Intel CPUs that may allow Spectre V2 style attacks. If 2691 disabled, mitigation cannot be enabled via cmdline. 2692 See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst> 2693 2694config MITIGATION_TSA 2695 bool "Mitigate Transient Scheduler Attacks" 2696 depends on CPU_SUP_AMD 2697 default y 2698 help 2699 Enable mitigation for Transient Scheduler Attacks. TSA is a hardware 2700 security vulnerability on AMD CPUs which can lead to forwarding of 2701 invalid info to subsequent instructions and thus can affect their 2702 timing and thereby cause a leakage. 2703 2704config MITIGATION_VMSCAPE 2705 bool "Mitigate VMSCAPE" 2706 depends on KVM 2707 default y 2708 help 2709 Enable mitigation for VMSCAPE attacks. VMSCAPE is a hardware security 2710 vulnerability on Intel and AMD CPUs that may allow a guest to do 2711 Spectre v2 style attacks on userspace hypervisor. 2712endif 2713 2714config ARCH_HAS_ADD_PAGES 2715 def_bool y 2716 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2717 2718menu "Power management and ACPI options" 2719 2720config ARCH_HIBERNATION_HEADER 2721 def_bool y 2722 depends on HIBERNATION 2723 2724source "kernel/power/Kconfig" 2725 2726source "drivers/acpi/Kconfig" 2727 2728config X86_APM_BOOT 2729 def_bool y 2730 depends on APM 2731 2732menuconfig APM 2733 tristate "APM (Advanced Power Management) BIOS support" 2734 depends on X86_32 && PM_SLEEP 2735 help 2736 APM is a BIOS specification for saving power using several different 2737 techniques. This is mostly useful for battery powered laptops with 2738 APM compliant BIOSes. If you say Y here, the system time will be 2739 reset after a RESUME operation, the /proc/apm device will provide 2740 battery status information, and user-space programs will receive 2741 notification of APM "events" (e.g. battery status change). 2742 2743 If you select "Y" here, you can disable actual use of the APM 2744 BIOS by passing the "apm=off" option to the kernel at boot time. 2745 2746 Note that the APM support is almost completely disabled for 2747 machines with more than one CPU. 2748 2749 In order to use APM, you will need supporting software. For location 2750 and more information, read <file:Documentation/power/apm-acpi.rst> 2751 and the Battery Powered Linux mini-HOWTO, available from 2752 <http://www.tldp.org/docs.html#howto>. 2753 2754 This driver does not spin down disk drives (see the hdparm(8) 2755 manpage ("man 8 hdparm") for that), and it doesn't turn off 2756 VESA-compliant "green" monitors. 2757 2758 This driver does not support the TI 4000M TravelMate and the ACER 2759 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2760 desktop machines also don't have compliant BIOSes, and this driver 2761 may cause those machines to panic during the boot phase. 2762 2763 Generally, if you don't have a battery in your machine, there isn't 2764 much point in using this driver and you should say N. If you get 2765 random kernel OOPSes or reboots that don't seem to be related to 2766 anything, try disabling/enabling this option (or disabling/enabling 2767 APM in your BIOS). 2768 2769 Some other things you should try when experiencing seemingly random, 2770 "weird" problems: 2771 2772 1) make sure that you have enough swap space and that it is 2773 enabled. 2774 2) pass the "idle=poll" option to the kernel 2775 3) switch on floating point emulation in the kernel and pass 2776 the "no387" option to the kernel 2777 4) pass the "floppy=nodma" option to the kernel 2778 5) pass the "mem=4M" option to the kernel (thereby disabling 2779 all but the first 4 MB of RAM) 2780 6) make sure that the CPU is not over clocked. 2781 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2782 8) disable the cache from your BIOS settings 2783 9) install a fan for the video card or exchange video RAM 2784 10) install a better fan for the CPU 2785 11) exchange RAM chips 2786 12) exchange the motherboard. 2787 2788 To compile this driver as a module, choose M here: the 2789 module will be called apm. 2790 2791if APM 2792 2793config APM_IGNORE_USER_SUSPEND 2794 bool "Ignore USER SUSPEND" 2795 help 2796 This option will ignore USER SUSPEND requests. On machines with a 2797 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2798 series notebooks, it is necessary to say Y because of a BIOS bug. 2799 2800config APM_DO_ENABLE 2801 bool "Enable PM at boot time" 2802 help 2803 Enable APM features at boot time. From page 36 of the APM BIOS 2804 specification: "When disabled, the APM BIOS does not automatically 2805 power manage devices, enter the Standby State, enter the Suspend 2806 State, or take power saving steps in response to CPU Idle calls." 2807 This driver will make CPU Idle calls when Linux is idle (unless this 2808 feature is turned off -- see "Do CPU IDLE calls", below). This 2809 should always save battery power, but more complicated APM features 2810 will be dependent on your BIOS implementation. You may need to turn 2811 this option off if your computer hangs at boot time when using APM 2812 support, or if it beeps continuously instead of suspending. Turn 2813 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2814 T400CDT. This is off by default since most machines do fine without 2815 this feature. 2816 2817config APM_CPU_IDLE 2818 depends on CPU_IDLE 2819 bool "Make CPU Idle calls when idle" 2820 help 2821 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2822 On some machines, this can activate improved power savings, such as 2823 a slowed CPU clock rate, when the machine is idle. These idle calls 2824 are made after the idle loop has run for some length of time (e.g., 2825 333 mS). On some machines, this will cause a hang at boot time or 2826 whenever the CPU becomes idle. (On machines with more than one CPU, 2827 this option does nothing.) 2828 2829config APM_DISPLAY_BLANK 2830 bool "Enable console blanking using APM" 2831 help 2832 Enable console blanking using the APM. Some laptops can use this to 2833 turn off the LCD backlight when the screen blanker of the Linux 2834 virtual console blanks the screen. Note that this is only used by 2835 the virtual console screen blanker, and won't turn off the backlight 2836 when using the X Window system. This also doesn't have anything to 2837 do with your VESA-compliant power-saving monitor. Further, this 2838 option doesn't work for all laptops -- it might not turn off your 2839 backlight at all, or it might print a lot of errors to the console, 2840 especially if you are using gpm. 2841 2842config APM_ALLOW_INTS 2843 bool "Allow interrupts during APM BIOS calls" 2844 help 2845 Normally we disable external interrupts while we are making calls to 2846 the APM BIOS as a measure to lessen the effects of a badly behaving 2847 BIOS implementation. The BIOS should reenable interrupts if it 2848 needs to. Unfortunately, some BIOSes do not -- especially those in 2849 many of the newer IBM Thinkpads. If you experience hangs when you 2850 suspend, try setting this to Y. Otherwise, say N. 2851 2852endif # APM 2853 2854source "drivers/cpufreq/Kconfig" 2855 2856source "drivers/cpuidle/Kconfig" 2857 2858source "drivers/idle/Kconfig" 2859 2860endmenu 2861 2862menu "Bus options (PCI etc.)" 2863 2864choice 2865 prompt "PCI access mode" 2866 depends on X86_32 && PCI 2867 default PCI_GOANY 2868 help 2869 On PCI systems, the BIOS can be used to detect the PCI devices and 2870 determine their configuration. However, some old PCI motherboards 2871 have BIOS bugs and may crash if this is done. Also, some embedded 2872 PCI-based systems don't have any BIOS at all. Linux can also try to 2873 detect the PCI hardware directly without using the BIOS. 2874 2875 With this option, you can specify how Linux should detect the 2876 PCI devices. If you choose "BIOS", the BIOS will be used, 2877 if you choose "Direct", the BIOS won't be used, and if you 2878 choose "MMConfig", then PCI Express MMCONFIG will be used. 2879 If you choose "Any", the kernel will try MMCONFIG, then the 2880 direct access method and falls back to the BIOS if that doesn't 2881 work. If unsure, go with the default, which is "Any". 2882 2883config PCI_GOBIOS 2884 bool "BIOS" 2885 2886config PCI_GOMMCONFIG 2887 bool "MMConfig" 2888 2889config PCI_GODIRECT 2890 bool "Direct" 2891 2892config PCI_GOOLPC 2893 bool "OLPC XO-1" 2894 depends on OLPC 2895 2896config PCI_GOANY 2897 bool "Any" 2898 2899endchoice 2900 2901config PCI_BIOS 2902 def_bool y 2903 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2904 2905# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2906config PCI_DIRECT 2907 def_bool y 2908 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2909 2910config PCI_MMCONFIG 2911 bool "Support mmconfig PCI config space access" if X86_64 2912 default y 2913 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2914 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2915 help 2916 Add support for accessing the PCI configuration space as a memory 2917 mapped area. It is the recommended method if the system supports 2918 this (it must have PCI Express and ACPI for it to be available). 2919 2920 In the unlikely case that enabling this configuration option causes 2921 problems, the mechanism can be switched off with the 'pci=nommconf' 2922 command line parameter. 2923 2924 Say N only if you are sure that your platform does not support this 2925 access method or you have problems caused by it. 2926 2927 Say Y otherwise. 2928 2929config PCI_OLPC 2930 def_bool y 2931 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2932 2933config PCI_XEN 2934 def_bool y 2935 depends on PCI && XEN 2936 2937config MMCONF_FAM10H 2938 def_bool y 2939 depends on X86_64 && PCI_MMCONFIG && ACPI 2940 2941config PCI_CNB20LE_QUIRK 2942 bool "Read PCI host bridge windows from the CNB20LE chipset" if EXPERT 2943 depends on X86_32 && PCI 2944 help 2945 Read the PCI windows out of the CNB20LE host bridge. This allows 2946 PCI hotplug to work on systems with the CNB20LE chipset which do 2947 not have ACPI. 2948 2949 The ServerWorks (later Broadcom) CNB20LE was a chipset designed 2950 most probably only for Pentium III. 2951 2952 To find out if you have such a chipset, search for a PCI device with 2953 1166:0009 PCI IDs, for example by executing 2954 lspci -nn | grep '1166:0009' 2955 The code is inactive if there is none. 2956 2957 There's no public spec for this chipset, and this functionality 2958 is known to be incomplete. 2959 2960 You should say N unless you know you need this. 2961 2962config ISA_BUS 2963 bool "ISA bus support on modern systems" if EXPERT 2964 help 2965 Expose ISA bus device drivers and options available for selection and 2966 configuration. Enable this option if your target machine has an ISA 2967 bus. ISA is an older system, displaced by PCI and newer bus 2968 architectures -- if your target machine is modern, it probably does 2969 not have an ISA bus. 2970 2971 If unsure, say N. 2972 2973# x86_64 have no ISA slots, but can have ISA-style DMA. 2974config ISA_DMA_API 2975 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2976 default y 2977 help 2978 Enables ISA-style DMA support for devices requiring such controllers. 2979 If unsure, say Y. 2980 2981if X86_32 2982 2983config ISA 2984 bool "ISA support" 2985 help 2986 Find out whether you have ISA slots on your motherboard. ISA is the 2987 name of a bus system, i.e. the way the CPU talks to the other stuff 2988 inside your box. Other bus systems are PCI, EISA, MicroChannel 2989 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2990 newer boards don't support it. If you have ISA, say Y, otherwise N. 2991 2992config SCx200 2993 tristate "NatSemi SCx200 support" 2994 help 2995 This provides basic support for National Semiconductor's 2996 (now AMD's) Geode processors. The driver probes for the 2997 PCI-IDs of several on-chip devices, so its a good dependency 2998 for other scx200_* drivers. 2999 3000 If compiled as a module, the driver is named scx200. 3001 3002config SCx200HR_TIMER 3003 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 3004 depends on SCx200 3005 default y 3006 help 3007 This driver provides a clocksource built upon the on-chip 3008 27MHz high-resolution timer. Its also a workaround for 3009 NSC Geode SC-1100's buggy TSC, which loses time when the 3010 processor goes idle (as is done by the scheduler). The 3011 other workaround is idle=poll boot option. 3012 3013config OLPC 3014 bool "One Laptop Per Child support" 3015 depends on !X86_PAE 3016 select GPIOLIB 3017 select OF 3018 select OF_PROMTREE 3019 select IRQ_DOMAIN 3020 select OLPC_EC 3021 help 3022 Add support for detecting the unique features of the OLPC 3023 XO hardware. 3024 3025config OLPC_XO1_PM 3026 bool "OLPC XO-1 Power Management" 3027 depends on OLPC && MFD_CS5535=y && PM_SLEEP 3028 help 3029 Add support for poweroff and suspend of the OLPC XO-1 laptop. 3030 3031config OLPC_XO1_RTC 3032 bool "OLPC XO-1 Real Time Clock" 3033 depends on OLPC_XO1_PM && RTC_DRV_CMOS 3034 help 3035 Add support for the XO-1 real time clock, which can be used as a 3036 programmable wakeup source. 3037 3038config OLPC_XO1_SCI 3039 bool "OLPC XO-1 SCI extras" 3040 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 3041 depends on INPUT=y 3042 select POWER_SUPPLY 3043 help 3044 Add support for SCI-based features of the OLPC XO-1 laptop: 3045 - EC-driven system wakeups 3046 - Power button 3047 - Ebook switch 3048 - Lid switch 3049 - AC adapter status updates 3050 - Battery status updates 3051 3052config OLPC_XO15_SCI 3053 bool "OLPC XO-1.5 SCI extras" 3054 depends on OLPC && ACPI 3055 select POWER_SUPPLY 3056 help 3057 Add support for SCI-based features of the OLPC XO-1.5 laptop: 3058 - EC-driven system wakeups 3059 - AC adapter status updates 3060 - Battery status updates 3061 3062config GEODE_COMMON 3063 bool 3064 3065config ALIX 3066 bool "PCEngines ALIX System Support (LED setup)" 3067 select GPIOLIB 3068 select GEODE_COMMON 3069 help 3070 This option enables system support for the PCEngines ALIX. 3071 At present this just sets up LEDs for GPIO control on 3072 ALIX2/3/6 boards. However, other system specific setup should 3073 get added here. 3074 3075 Note: You must still enable the drivers for GPIO and LED support 3076 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 3077 3078 Note: You have to set alix.force=1 for boards with Award BIOS. 3079 3080config NET5501 3081 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3082 select GPIOLIB 3083 select GEODE_COMMON 3084 help 3085 This option enables system support for the Soekris Engineering net5501. 3086 3087config GEOS 3088 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3089 select GPIOLIB 3090 select GEODE_COMMON 3091 depends on DMI 3092 help 3093 This option enables system support for the Traverse Technologies GEOS. 3094 3095config TS5500 3096 bool "Technologic Systems TS-5500 platform support" 3097 depends on MELAN 3098 select CHECK_SIGNATURE 3099 select NEW_LEDS 3100 select LEDS_CLASS 3101 help 3102 This option enables system support for the Technologic Systems TS-5500. 3103 3104endif # X86_32 3105 3106config AMD_NB 3107 def_bool y 3108 depends on AMD_NODE 3109 3110config AMD_NODE 3111 def_bool y 3112 depends on CPU_SUP_AMD && PCI 3113 3114endmenu 3115 3116menu "Binary Emulations" 3117 3118config IA32_EMULATION 3119 bool "IA32 Emulation" 3120 depends on X86_64 3121 select ARCH_WANT_OLD_COMPAT_IPC 3122 select BINFMT_ELF 3123 select COMPAT_OLD_SIGACTION 3124 help 3125 Include code to run legacy 32-bit programs under a 3126 64-bit kernel. You should likely turn this on, unless you're 3127 100% sure that you don't have any 32-bit programs left. 3128 3129config IA32_EMULATION_DEFAULT_DISABLED 3130 bool "IA32 emulation disabled by default" 3131 default n 3132 depends on IA32_EMULATION 3133 help 3134 Make IA32 emulation disabled by default. This prevents loading 32-bit 3135 processes and access to 32-bit syscalls. If unsure, leave it to its 3136 default value. 3137 3138config X86_X32_ABI 3139 bool "x32 ABI for 64-bit mode" 3140 depends on X86_64 3141 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3142 # compressed debug sections to x86_x32 properly: 3143 # https://github.com/ClangBuiltLinux/linux/issues/514 3144 # https://github.com/ClangBuiltLinux/linux/issues/1141 3145 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3146 help 3147 Include code to run binaries for the x32 native 32-bit ABI 3148 for 64-bit processors. An x32 process gets access to the 3149 full 64-bit register file and wide data path while leaving 3150 pointers at 32 bits for smaller memory footprint. 3151 3152config COMPAT_32 3153 def_bool y 3154 depends on IA32_EMULATION || X86_32 3155 select HAVE_UID16 3156 select OLD_SIGSUSPEND3 3157 3158config COMPAT 3159 def_bool y 3160 depends on IA32_EMULATION || X86_X32_ABI 3161 3162config COMPAT_FOR_U64_ALIGNMENT 3163 def_bool y 3164 depends on COMPAT 3165 3166endmenu 3167 3168config HAVE_ATOMIC_IOMAP 3169 def_bool y 3170 depends on X86_32 3171 3172source "arch/x86/kvm/Kconfig" 3173 3174source "arch/x86/Kconfig.cpufeatures" 3175 3176source "arch/x86/Kconfig.assembler" 3177