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