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 GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_HAS_PTDUMP 30 select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 31 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 32 select ARCH_SUPPORTS_PER_VMA_LOCK 33 select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE 34 select HAVE_ARCH_SOFT_DIRTY 35 select MODULES_USE_ELF_RELA 36 select NEED_DMA_MAP_STATE 37 select SWIOTLB 38 select ARCH_HAS_ELFCORE_COMPAT 39 select ZONE_DMA32 40 select EXECMEM if DYNAMIC_FTRACE 41 42config FORCE_DYNAMIC_FTRACE 43 def_bool y 44 depends on X86_32 45 depends on FUNCTION_TRACER 46 select DYNAMIC_FTRACE 47 help 48 We keep the static function tracing (!DYNAMIC_FTRACE) around 49 in order to test the non static function tracing in the 50 generic code, as other architectures still use it. But we 51 only need to keep it around for x86_64. No need to keep it 52 for x86_32. For x86_32, force DYNAMIC_FTRACE. 53# 54# Arch settings 55# 56# ( Note that options that are marked 'if X86_64' could in principle be 57# ported to 32-bit as well. ) 58# 59config X86 60 def_bool y 61 # 62 # Note: keep this list sorted alphabetically 63 # 64 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 65 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 66 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 67 select ARCH_32BIT_OFF_T if X86_32 68 select ARCH_CLOCKSOURCE_INIT 69 select ARCH_CONFIGURES_CPU_MITIGATIONS 70 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 71 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 72 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 73 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 74 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 75 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 76 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 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_CRC32 82 select ARCH_HAS_CRC64 if X86_64 83 select ARCH_HAS_CRC_T10DIF 84 select ARCH_HAS_CURRENT_STACK_POINTER 85 select ARCH_HAS_DEBUG_VIRTUAL 86 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 87 select ARCH_HAS_DEVMEM_IS_ALLOWED 88 select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN 89 select ARCH_HAS_EARLY_DEBUG if KGDB 90 select ARCH_HAS_ELF_RANDOMIZE 91 select ARCH_HAS_EXECMEM_ROX if X86_64 92 select ARCH_HAS_FAST_MULTIPLIER 93 select ARCH_HAS_FORTIFY_SOURCE 94 select ARCH_HAS_GCOV_PROFILE_ALL 95 select ARCH_HAS_KCOV if X86_64 96 select ARCH_HAS_KERNEL_FPU_SUPPORT 97 select ARCH_HAS_MEM_ENCRYPT 98 select ARCH_HAS_MEMBARRIER_SYNC_CORE 99 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 100 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 101 select ARCH_HAS_PMEM_API if X86_64 102 select ARCH_HAS_PREEMPT_LAZY 103 select ARCH_HAS_PTE_DEVMAP if X86_64 104 select ARCH_HAS_PTE_SPECIAL 105 select ARCH_HAS_HW_PTE_YOUNG 106 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 107 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 108 select ARCH_HAS_COPY_MC if X86_64 109 select ARCH_HAS_SET_MEMORY 110 select ARCH_HAS_SET_DIRECT_MAP 111 select ARCH_HAS_STRICT_KERNEL_RWX 112 select ARCH_HAS_STRICT_MODULE_RWX 113 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 114 select ARCH_HAS_SYSCALL_WRAPPER 115 select ARCH_HAS_UBSAN 116 select ARCH_HAS_DEBUG_WX 117 select ARCH_HAS_ZONE_DMA_SET if EXPERT 118 select ARCH_HAVE_NMI_SAFE_CMPXCHG 119 select ARCH_HAVE_EXTRA_ELF_NOTES 120 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 121 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 122 select ARCH_MIGHT_HAVE_PC_PARPORT 123 select ARCH_MIGHT_HAVE_PC_SERIO 124 select ARCH_STACKWALK 125 select ARCH_SUPPORTS_ACPI 126 select ARCH_SUPPORTS_ATOMIC_RMW 127 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 128 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 129 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 130 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 131 select ARCH_SUPPORTS_CFI_CLANG if X86_64 132 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 133 select ARCH_SUPPORTS_LTO_CLANG 134 select ARCH_SUPPORTS_LTO_CLANG_THIN 135 select ARCH_SUPPORTS_RT 136 select ARCH_SUPPORTS_AUTOFDO_CLANG 137 select ARCH_SUPPORTS_PROPELLER_CLANG if X86_64 138 select ARCH_USE_BUILTIN_BSWAP 139 select ARCH_USE_CMPXCHG_LOCKREF if X86_CX8 140 select ARCH_USE_MEMTEST 141 select ARCH_USE_QUEUED_RWLOCKS 142 select ARCH_USE_QUEUED_SPINLOCKS 143 select ARCH_USE_SYM_ANNOTATIONS 144 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 145 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 146 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 147 select ARCH_WANTS_NO_INSTR 148 select ARCH_WANT_GENERAL_HUGETLB 149 select ARCH_WANT_HUGE_PMD_SHARE 150 select ARCH_WANT_LD_ORPHAN_WARN 151 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 152 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 153 select ARCH_WANT_HUGETLB_VMEMMAP_PREINIT if X86_64 154 select ARCH_WANTS_THP_SWAP if X86_64 155 select ARCH_HAS_PARANOID_L1D_FLUSH 156 select ARCH_WANT_IRQS_OFF_ACTIVATE_MM 157 select BUILDTIME_TABLE_SORT 158 select CLKEVT_I8253 159 select CLOCKSOURCE_WATCHDOG 160 # Word-size accesses may read uninitialized data past the trailing \0 161 # in strings and cause false KMSAN reports. 162 select DCACHE_WORD_ACCESS if !KMSAN 163 select DYNAMIC_SIGFRAME 164 select EDAC_ATOMIC_SCRUB 165 select EDAC_SUPPORT 166 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 167 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 168 select GENERIC_CLOCKEVENTS_MIN_ADJUST 169 select GENERIC_CMOS_UPDATE 170 select GENERIC_CPU_AUTOPROBE 171 select GENERIC_CPU_DEVICES 172 select GENERIC_CPU_VULNERABILITIES 173 select GENERIC_EARLY_IOREMAP 174 select GENERIC_ENTRY 175 select GENERIC_IOMAP 176 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 177 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 178 select GENERIC_IRQ_MIGRATION if SMP 179 select GENERIC_IRQ_PROBE 180 select GENERIC_IRQ_RESERVATION_MODE 181 select GENERIC_IRQ_SHOW 182 select GENERIC_PENDING_IRQ if SMP 183 select GENERIC_SMP_IDLE_THREAD 184 select GENERIC_TIME_VSYSCALL 185 select GENERIC_GETTIMEOFDAY 186 select GENERIC_VDSO_DATA_STORE 187 select GENERIC_VDSO_TIME_NS 188 select GENERIC_VDSO_OVERFLOW_PROTECT 189 select GUP_GET_PXX_LOW_HIGH if X86_PAE 190 select HARDIRQS_SW_RESEND 191 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 192 select HAS_IOPORT 193 select HAVE_ACPI_APEI if ACPI 194 select HAVE_ACPI_APEI_NMI if ACPI 195 select HAVE_ALIGNED_STRUCT_PAGE 196 select HAVE_ARCH_AUDITSYSCALL 197 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 198 select HAVE_ARCH_HUGE_VMALLOC if X86_64 199 select HAVE_ARCH_JUMP_LABEL 200 select HAVE_ARCH_JUMP_LABEL_RELATIVE 201 select HAVE_ARCH_KASAN if X86_64 202 select HAVE_ARCH_KASAN_VMALLOC if X86_64 203 select HAVE_ARCH_KFENCE 204 select HAVE_ARCH_KMSAN if X86_64 205 select HAVE_ARCH_KGDB 206 select HAVE_ARCH_MMAP_RND_BITS if MMU 207 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 208 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 209 select HAVE_ARCH_PREL32_RELOCATIONS 210 select HAVE_ARCH_SECCOMP_FILTER 211 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 212 select HAVE_ARCH_STACKLEAK 213 select HAVE_ARCH_TRACEHOOK 214 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 215 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 216 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 217 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 218 select HAVE_ARCH_VMAP_STACK if X86_64 219 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 220 select HAVE_ARCH_WITHIN_STACK_FRAMES 221 select HAVE_ASM_MODVERSIONS 222 select HAVE_CMPXCHG_DOUBLE 223 select HAVE_CMPXCHG_LOCAL 224 select HAVE_CONTEXT_TRACKING_USER if X86_64 225 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 226 select HAVE_C_RECORDMCOUNT 227 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 228 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 229 select HAVE_BUILDTIME_MCOUNT_SORT 230 select HAVE_DEBUG_KMEMLEAK 231 select HAVE_DMA_CONTIGUOUS 232 select HAVE_DYNAMIC_FTRACE 233 select HAVE_DYNAMIC_FTRACE_WITH_REGS 234 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 235 select HAVE_FTRACE_REGS_HAVING_PT_REGS if X86_64 236 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 237 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 238 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 239 select HAVE_EBPF_JIT 240 select HAVE_EFFICIENT_UNALIGNED_ACCESS 241 select HAVE_EISA if X86_32 242 select HAVE_EXIT_THREAD 243 select HAVE_GUP_FAST 244 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 245 select HAVE_FTRACE_GRAPH_FUNC if HAVE_FUNCTION_GRAPH_TRACER 246 select HAVE_FTRACE_MCOUNT_RECORD 247 select HAVE_FUNCTION_GRAPH_FREGS if HAVE_FUNCTION_GRAPH_TRACER 248 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 249 select HAVE_FUNCTION_TRACER 250 select HAVE_GCC_PLUGINS 251 select HAVE_HW_BREAKPOINT 252 select HAVE_IOREMAP_PROT 253 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 254 select HAVE_IRQ_TIME_ACCOUNTING 255 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 256 select HAVE_KERNEL_BZIP2 257 select HAVE_KERNEL_GZIP 258 select HAVE_KERNEL_LZ4 259 select HAVE_KERNEL_LZMA 260 select HAVE_KERNEL_LZO 261 select HAVE_KERNEL_XZ 262 select HAVE_KERNEL_ZSTD 263 select HAVE_KPROBES 264 select HAVE_KPROBES_ON_FTRACE 265 select HAVE_FUNCTION_ERROR_INJECTION 266 select HAVE_KRETPROBES 267 select HAVE_RETHOOK 268 select HAVE_LIVEPATCH if X86_64 269 select HAVE_MIXED_BREAKPOINTS_REGS 270 select HAVE_MOD_ARCH_SPECIFIC 271 select HAVE_MOVE_PMD 272 select HAVE_MOVE_PUD 273 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 274 select HAVE_NMI 275 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 276 select HAVE_OBJTOOL if X86_64 277 select HAVE_OPTPROBES 278 select HAVE_PAGE_SIZE_4KB 279 select HAVE_PCSPKR_PLATFORM 280 select HAVE_PERF_EVENTS 281 select HAVE_PERF_EVENTS_NMI 282 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 283 select HAVE_PCI 284 select HAVE_PERF_REGS 285 select HAVE_PERF_USER_STACK_DUMP 286 select MMU_GATHER_RCU_TABLE_FREE 287 select MMU_GATHER_MERGE_VMAS 288 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 289 select HAVE_REGS_AND_STACK_ACCESS_API 290 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 291 select HAVE_FUNCTION_ARG_ACCESS_API 292 select HAVE_SETUP_PER_CPU_AREA 293 select HAVE_SOFTIRQ_ON_OWN_STACK 294 select HAVE_STACKPROTECTOR 295 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 296 select HAVE_STATIC_CALL 297 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 298 select HAVE_PREEMPT_DYNAMIC_CALL 299 select HAVE_RSEQ 300 select HAVE_RUST if X86_64 301 select HAVE_SYSCALL_TRACEPOINTS 302 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 303 select HAVE_UNSTABLE_SCHED_CLOCK 304 select HAVE_USER_RETURN_NOTIFIER 305 select HAVE_GENERIC_VDSO 306 select VDSO_GETRANDOM if X86_64 307 select HOTPLUG_PARALLEL if SMP && X86_64 308 select HOTPLUG_SMT if SMP 309 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 310 select IRQ_FORCED_THREADING 311 select LOCK_MM_AND_FIND_VMA 312 select NEED_PER_CPU_EMBED_FIRST_CHUNK 313 select NEED_PER_CPU_PAGE_FIRST_CHUNK 314 select NEED_SG_DMA_LENGTH 315 select NUMA_MEMBLKS if NUMA 316 select PCI_DOMAINS if PCI 317 select PCI_LOCKLESS_CONFIG if PCI 318 select PERF_EVENTS 319 select RTC_LIB 320 select RTC_MC146818_LIB 321 select SPARSE_IRQ 322 select SYSCTL_EXCEPTION_TRACE 323 select THREAD_INFO_IN_TASK 324 select TRACE_IRQFLAGS_SUPPORT 325 select TRACE_IRQFLAGS_NMI_SUPPORT 326 select USER_STACKTRACE_SUPPORT 327 select HAVE_ARCH_KCSAN if X86_64 328 select PROC_PID_ARCH_STATUS if PROC_FS 329 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 330 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 331 select FUNCTION_ALIGNMENT_4B 332 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 333 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 334 select ARCH_SUPPORTS_PT_RECLAIM if X86_64 335 336config INSTRUCTION_DECODER 337 def_bool y 338 depends on KPROBES || PERF_EVENTS || UPROBES 339 340config OUTPUT_FORMAT 341 string 342 default "elf32-i386" if X86_32 343 default "elf64-x86-64" if X86_64 344 345config LOCKDEP_SUPPORT 346 def_bool y 347 348config STACKTRACE_SUPPORT 349 def_bool y 350 351config MMU 352 def_bool y 353 354config ARCH_MMAP_RND_BITS_MIN 355 default 28 if 64BIT 356 default 8 357 358config ARCH_MMAP_RND_BITS_MAX 359 default 32 if 64BIT 360 default 16 361 362config ARCH_MMAP_RND_COMPAT_BITS_MIN 363 default 8 364 365config ARCH_MMAP_RND_COMPAT_BITS_MAX 366 default 16 367 368config SBUS 369 bool 370 371config GENERIC_ISA_DMA 372 def_bool y 373 depends on ISA_DMA_API 374 375config GENERIC_CSUM 376 bool 377 default y if KMSAN || KASAN 378 379config GENERIC_BUG 380 def_bool y 381 depends on BUG 382 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 383 384config GENERIC_BUG_RELATIVE_POINTERS 385 bool 386 387config ARCH_MAY_HAVE_PC_FDC 388 def_bool y 389 depends on ISA_DMA_API 390 391config GENERIC_CALIBRATE_DELAY 392 def_bool y 393 394config ARCH_HAS_CPU_RELAX 395 def_bool y 396 397config ARCH_HIBERNATION_POSSIBLE 398 def_bool y 399 400config ARCH_SUSPEND_POSSIBLE 401 def_bool y 402 403config AUDIT_ARCH 404 def_bool y if X86_64 405 406config KASAN_SHADOW_OFFSET 407 hex 408 depends on KASAN 409 default 0xdffffc0000000000 410 411config HAVE_INTEL_TXT 412 def_bool y 413 depends on INTEL_IOMMU && ACPI 414 415config X86_64_SMP 416 def_bool y 417 depends on X86_64 && SMP 418 419config ARCH_SUPPORTS_UPROBES 420 def_bool y 421 422config FIX_EARLYCON_MEM 423 def_bool y 424 425config DYNAMIC_PHYSICAL_MASK 426 bool 427 428config PGTABLE_LEVELS 429 int 430 default 5 if X86_64 431 default 3 if X86_PAE 432 default 2 433 434menu "Processor type and features" 435 436config SMP 437 bool "Symmetric multi-processing support" 438 help 439 This enables support for systems with more than one CPU. If you have 440 a system with only one CPU, say N. If you have a system with more 441 than one CPU, say Y. 442 443 If you say N here, the kernel will run on uni- and multiprocessor 444 machines, but will use only one CPU of a multiprocessor machine. If 445 you say Y here, the kernel will run on many, but not all, 446 uniprocessor machines. On a uniprocessor machine, the kernel 447 will run faster if you say N here. 448 449 Note that if you say Y here and choose architecture "586" or 450 "Pentium" under "Processor family", the kernel will not work on 486 451 architectures. Similarly, multiprocessor kernels for the "PPro" 452 architecture may not work on all Pentium based boards. 453 454 People using multiprocessor machines who say Y here should also say 455 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 456 Management" code will be disabled if you say Y here. 457 458 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 459 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 460 <http://www.tldp.org/docs.html#howto>. 461 462 If you don't know what to do here, say N. 463 464config X86_X2APIC 465 bool "x2APIC interrupt controller architecture support" 466 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 467 default y 468 help 469 x2APIC is an interrupt controller architecture, a component of which 470 (the local APIC) is present in the CPU. It allows faster access to 471 the local APIC and supports a larger number of CPUs in the system 472 than the predecessors. 473 474 x2APIC was introduced in Intel CPUs around 2008 and in AMD EPYC CPUs 475 in 2019, but it can be disabled by the BIOS. It is also frequently 476 emulated in virtual machines, even when the host CPU does not support 477 it. Support in the CPU can be checked by executing 478 grep x2apic /proc/cpuinfo 479 480 If this configuration option is disabled, the kernel will boot with 481 very reduced functionality and performance on some platforms that 482 have x2APIC enabled. On the other hand, on hardware that does not 483 support x2APIC, a kernel with this option enabled will just fallback 484 to older APIC implementations. 485 486 If in doubt, say Y. 487 488config X86_POSTED_MSI 489 bool "Enable MSI and MSI-x delivery by posted interrupts" 490 depends on X86_64 && IRQ_REMAP 491 help 492 This enables MSIs that are under interrupt remapping to be delivered as 493 posted interrupts to the host kernel. Interrupt throughput can 494 potentially be improved by coalescing CPU notifications during high 495 frequency bursts. 496 497 If you don't know what to do here, say N. 498 499config X86_MPPARSE 500 bool "Enable MPS table" if ACPI 501 default y 502 depends on X86_LOCAL_APIC 503 help 504 For old smp systems that do not have proper acpi support. Newer systems 505 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 506 507config X86_CPU_RESCTRL 508 bool "x86 CPU resource control support" 509 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 510 select KERNFS 511 select PROC_CPU_RESCTRL if PROC_FS 512 select RESCTRL_FS_PSEUDO_LOCK 513 help 514 Enable x86 CPU resource control support. 515 516 Provide support for the allocation and monitoring of system resources 517 usage by the CPU. 518 519 Intel calls this Intel Resource Director Technology 520 (Intel(R) RDT). More information about RDT can be found in the 521 Intel x86 Architecture Software Developer Manual. 522 523 AMD calls this AMD Platform Quality of Service (AMD QoS). 524 More information about AMD QoS can be found in the AMD64 Technology 525 Platform Quality of Service Extensions manual. 526 527 Say N if unsure. 528 529config RESCTRL_FS_PSEUDO_LOCK 530 bool 531 help 532 Software mechanism to pin data in a cache portion using 533 micro-architecture specific knowledge. 534 535config X86_FRED 536 bool "Flexible Return and Event Delivery" 537 depends on X86_64 538 help 539 When enabled, try to use Flexible Return and Event Delivery 540 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 541 ring transitions and exception/interrupt handling if the 542 system supports it. 543 544config X86_EXTENDED_PLATFORM 545 bool "Support for extended (non-PC) x86 platforms" 546 default y 547 help 548 If you disable this option then the kernel will only support 549 standard PC platforms. (which covers the vast majority of 550 systems out there.) 551 552 If you enable this option then you'll be able to select support 553 for the following non-PC x86 platforms, depending on the value of 554 CONFIG_64BIT. 555 556 32-bit platforms (CONFIG_64BIT=n): 557 Goldfish (mostly Android emulator) 558 Intel CE media processor (CE4100) SoC 559 Intel Quark 560 RDC R-321x SoC 561 562 64-bit platforms (CONFIG_64BIT=y): 563 Numascale NumaChip 564 ScaleMP vSMP 565 SGI Ultraviolet 566 Merrifield/Moorefield MID devices 567 Goldfish (mostly Android emulator) 568 569 If you have one of these systems, or if you want to build a 570 generic distribution kernel, say Y here - otherwise say N. 571 572# This is an alphabetically sorted list of 64 bit extended platforms 573# Please maintain the alphabetic order if and when there are additions 574config X86_NUMACHIP 575 bool "Numascale NumaChip" 576 depends on X86_64 577 depends on X86_EXTENDED_PLATFORM 578 depends on NUMA 579 depends on SMP 580 depends on X86_X2APIC 581 depends on PCI_MMCONFIG 582 help 583 Adds support for Numascale NumaChip large-SMP systems. Needed to 584 enable more than ~168 cores. 585 If you don't have one of these, you should say N here. 586 587config X86_VSMP 588 bool "ScaleMP vSMP" 589 select HYPERVISOR_GUEST 590 select PARAVIRT 591 depends on X86_64 && PCI 592 depends on X86_EXTENDED_PLATFORM 593 depends on SMP 594 help 595 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 596 supposed to run on these EM64T-based machines. Only choose this option 597 if you have one of these machines. 598 599config X86_UV 600 bool "SGI Ultraviolet" 601 depends on X86_64 602 depends on X86_EXTENDED_PLATFORM 603 depends on NUMA 604 depends on EFI 605 depends on KEXEC_CORE 606 depends on X86_X2APIC 607 depends on PCI 608 help 609 This option is needed in order to support SGI Ultraviolet systems. 610 If you don't have one of these, you should say N here. 611 612config X86_INTEL_MID 613 bool "Intel Z34xx/Z35xx MID platform support" 614 depends on X86_EXTENDED_PLATFORM 615 depends on X86_PLATFORM_DEVICES 616 depends on PCI 617 depends on X86_64 || (EXPERT && PCI_GOANY) 618 depends on X86_IO_APIC 619 select I2C 620 select DW_APB_TIMER 621 select INTEL_SCU_PCI 622 help 623 Select to build a kernel capable of supporting 64-bit Intel MID 624 (Mobile Internet Device) platform systems which do not have 625 the PCI legacy interfaces. 626 627 The only supported devices are the 22nm Merrified (Z34xx) 628 and Moorefield (Z35xx) SoC used in the Intel Edison board and 629 a small number of Android devices such as the Asus Zenfone 2, 630 Asus FonePad 8 and Dell Venue 7. 631 632 If you are building for a PC class system or non-MID tablet 633 SoCs like Bay Trail (Z36xx/Z37xx), say N here. 634 635 Intel MID platforms are based on an Intel processor and chipset which 636 consume less power than most of the x86 derivatives. 637 638config X86_GOLDFISH 639 bool "Goldfish (Virtual Platform)" 640 depends on X86_EXTENDED_PLATFORM 641 help 642 Enable support for the Goldfish virtual platform used primarily 643 for Android development. Unless you are building for the Android 644 Goldfish emulator say N here. 645 646# Following is an alphabetically sorted list of 32 bit extended platforms 647# Please maintain the alphabetic order if and when there are additions 648 649config X86_INTEL_CE 650 bool "CE4100 TV platform" 651 depends on PCI 652 depends on PCI_GODIRECT 653 depends on X86_IO_APIC 654 depends on X86_32 655 depends on X86_EXTENDED_PLATFORM 656 select X86_REBOOTFIXUPS 657 select OF 658 select OF_EARLY_FLATTREE 659 help 660 Select for the Intel CE media processor (CE4100) SOC. 661 This option compiles in support for the CE4100 SOC for settop 662 boxes and media devices. 663 664config X86_INTEL_QUARK 665 bool "Intel Quark platform support" 666 depends on X86_32 667 depends on X86_EXTENDED_PLATFORM 668 depends on X86_PLATFORM_DEVICES 669 depends on X86_TSC 670 depends on PCI 671 depends on PCI_GOANY 672 depends on X86_IO_APIC 673 select IOSF_MBI 674 select INTEL_IMR 675 select COMMON_CLK 676 help 677 Select to include support for Quark X1000 SoC. 678 Say Y here if you have a Quark based system such as the Arduino 679 compatible Intel Galileo. 680 681config X86_RDC321X 682 bool "RDC R-321x SoC" 683 depends on X86_32 684 depends on X86_EXTENDED_PLATFORM 685 select M486 686 select X86_REBOOTFIXUPS 687 help 688 This option is needed for RDC R-321x system-on-chip, also known 689 as R-8610-(G). 690 If you don't have one of these chips, you should say N here. 691 692config X86_INTEL_LPSS 693 bool "Intel Low Power Subsystem Support" 694 depends on X86 && ACPI && PCI 695 select COMMON_CLK 696 select PINCTRL 697 select IOSF_MBI 698 help 699 Select to build support for Intel Low Power Subsystem such as 700 found on Intel Lynxpoint PCH. Selecting this option enables 701 things like clock tree (common clock framework) and pincontrol 702 which are needed by the LPSS peripheral drivers. 703 704config X86_AMD_PLATFORM_DEVICE 705 bool "AMD ACPI2Platform devices support" 706 depends on ACPI 707 select COMMON_CLK 708 select PINCTRL 709 help 710 Select to interpret AMD specific ACPI device to platform device 711 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 712 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 713 implemented under PINCTRL subsystem. 714 715config IOSF_MBI 716 tristate "Intel SoC IOSF Sideband support for SoC platforms" 717 depends on PCI 718 help 719 This option enables sideband register access support for Intel SoC 720 platforms. On these platforms the IOSF sideband is used in lieu of 721 MSR's for some register accesses, mostly but not limited to thermal 722 and power. Drivers may query the availability of this device to 723 determine if they need the sideband in order to work on these 724 platforms. The sideband is available on the following SoC products. 725 This list is not meant to be exclusive. 726 - BayTrail 727 - Braswell 728 - Quark 729 730 You should say Y if you are running a kernel on one of these SoC's. 731 732config IOSF_MBI_DEBUG 733 bool "Enable IOSF sideband access through debugfs" 734 depends on IOSF_MBI && DEBUG_FS 735 help 736 Select this option to expose the IOSF sideband access registers (MCR, 737 MDR, MCRX) through debugfs to write and read register information from 738 different units on the SoC. This is most useful for obtaining device 739 state information for debug and analysis. As this is a general access 740 mechanism, users of this option would have specific knowledge of the 741 device they want to access. 742 743 If you don't require the option or are in doubt, say N. 744 745config X86_SUPPORTS_MEMORY_FAILURE 746 def_bool y 747 # MCE code calls memory_failure(): 748 depends on X86_MCE 749 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 750 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 751 depends on X86_64 || !SPARSEMEM 752 select ARCH_SUPPORTS_MEMORY_FAILURE 753 754config X86_32_IRIS 755 tristate "Eurobraille/Iris poweroff module" 756 depends on X86_32 757 help 758 The Iris machines from EuroBraille do not have APM or ACPI support 759 to shut themselves down properly. A special I/O sequence is 760 needed to do so, which is what this module does at 761 kernel shutdown. 762 763 This is only for Iris machines from EuroBraille. 764 765 If unused, say N. 766 767config SCHED_OMIT_FRAME_POINTER 768 def_bool y 769 prompt "Single-depth WCHAN output" 770 depends on X86 771 help 772 Calculate simpler /proc/<PID>/wchan values. If this option 773 is disabled then wchan values will recurse back to the 774 caller function. This provides more accurate wchan values, 775 at the expense of slightly more scheduling overhead. 776 777 If in doubt, say "Y". 778 779menuconfig HYPERVISOR_GUEST 780 bool "Linux guest support" 781 help 782 Say Y here to enable options for running Linux under various hyper- 783 visors. This option enables basic hypervisor detection and platform 784 setup. 785 786 If you say N, all options in this submenu will be skipped and 787 disabled, and Linux guest support won't be built in. 788 789if HYPERVISOR_GUEST 790 791config PARAVIRT 792 bool "Enable paravirtualization code" 793 depends on HAVE_STATIC_CALL 794 help 795 This changes the kernel so it can modify itself when it is run 796 under a hypervisor, potentially improving performance significantly 797 over full virtualization. However, when run without a hypervisor 798 the kernel is theoretically slower and slightly larger. 799 800config PARAVIRT_XXL 801 bool 802 depends on X86_64 803 804config PARAVIRT_DEBUG 805 bool "paravirt-ops debugging" 806 depends on PARAVIRT && DEBUG_KERNEL 807 help 808 Enable to debug paravirt_ops internals. Specifically, BUG if 809 a paravirt_op is missing when it is called. 810 811config PARAVIRT_SPINLOCKS 812 bool "Paravirtualization layer for spinlocks" 813 depends on PARAVIRT && SMP 814 help 815 Paravirtualized spinlocks allow a pvops backend to replace the 816 spinlock implementation with something virtualization-friendly 817 (for example, block the virtual CPU rather than spinning). 818 819 It has a minimal impact on native kernels and gives a nice performance 820 benefit on paravirtualized KVM / Xen kernels. 821 822 If you are unsure how to answer this question, answer Y. 823 824config X86_HV_CALLBACK_VECTOR 825 def_bool n 826 827source "arch/x86/xen/Kconfig" 828 829config KVM_GUEST 830 bool "KVM Guest support (including kvmclock)" 831 depends on PARAVIRT 832 select PARAVIRT_CLOCK 833 select ARCH_CPUIDLE_HALTPOLL 834 select X86_HV_CALLBACK_VECTOR 835 default y 836 help 837 This option enables various optimizations for running under the KVM 838 hypervisor. It includes a paravirtualized clock, so that instead 839 of relying on a PIT (or probably other) emulation by the 840 underlying device model, the host provides the guest with 841 timing infrastructure such as time of day, and system time 842 843config ARCH_CPUIDLE_HALTPOLL 844 def_bool n 845 prompt "Disable host haltpoll when loading haltpoll driver" 846 help 847 If virtualized under KVM, disable host haltpoll. 848 849config PVH 850 bool "Support for running PVH guests" 851 help 852 This option enables the PVH entry point for guest virtual machines 853 as specified in the x86/HVM direct boot ABI. 854 855config PARAVIRT_TIME_ACCOUNTING 856 bool "Paravirtual steal time accounting" 857 depends on PARAVIRT 858 help 859 Select this option to enable fine granularity task steal time 860 accounting. Time spent executing other tasks in parallel with 861 the current vCPU is discounted from the vCPU power. To account for 862 that, there can be a small performance impact. 863 864 If in doubt, say N here. 865 866config PARAVIRT_CLOCK 867 bool 868 869config JAILHOUSE_GUEST 870 bool "Jailhouse non-root cell support" 871 depends on X86_64 && PCI 872 select X86_PM_TIMER 873 help 874 This option allows to run Linux as guest in a Jailhouse non-root 875 cell. You can leave this option disabled if you only want to start 876 Jailhouse and run Linux afterwards in the root cell. 877 878config ACRN_GUEST 879 bool "ACRN Guest support" 880 depends on X86_64 881 select X86_HV_CALLBACK_VECTOR 882 help 883 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 884 a flexible, lightweight reference open-source hypervisor, built with 885 real-time and safety-criticality in mind. It is built for embedded 886 IOT with small footprint and real-time features. More details can be 887 found in https://projectacrn.org/. 888 889config INTEL_TDX_GUEST 890 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 891 depends on X86_64 && CPU_SUP_INTEL 892 depends on X86_X2APIC 893 depends on EFI_STUB 894 depends on PARAVIRT 895 select ARCH_HAS_CC_PLATFORM 896 select X86_MEM_ENCRYPT 897 select X86_MCE 898 select UNACCEPTED_MEMORY 899 help 900 Support running as a guest under Intel TDX. Without this support, 901 the guest kernel can not boot or run under TDX. 902 TDX includes memory encryption and integrity capabilities 903 which protect the confidentiality and integrity of guest 904 memory contents and CPU state. TDX guests are protected from 905 some attacks from the VMM. 906 907endif # HYPERVISOR_GUEST 908 909source "arch/x86/Kconfig.cpu" 910 911config HPET_TIMER 912 def_bool X86_64 913 prompt "HPET Timer Support" if X86_32 914 help 915 Use the IA-PC HPET (High Precision Event Timer) to manage 916 time in preference to the PIT and RTC, if a HPET is 917 present. 918 HPET is the next generation timer replacing legacy 8254s. 919 The HPET provides a stable time base on SMP 920 systems, unlike the TSC, but it is more expensive to access, 921 as it is off-chip. The interface used is documented 922 in the HPET spec, revision 1. 923 924 You can safely choose Y here. However, HPET will only be 925 activated if the platform and the BIOS support this feature. 926 Otherwise the 8254 will be used for timing services. 927 928 Choose N to continue using the legacy 8254 timer. 929 930config HPET_EMULATE_RTC 931 def_bool y 932 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 933 934# Mark as expert because too many people got it wrong. 935# The code disables itself when not needed. 936config DMI 937 default y 938 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 939 bool "Enable DMI scanning" if EXPERT 940 help 941 Enabled scanning of DMI to identify machine quirks. Say Y 942 here unless you have verified that your setup is not 943 affected by entries in the DMI blacklist. Required by PNP 944 BIOS code. 945 946config GART_IOMMU 947 bool "Old AMD GART IOMMU support" 948 select IOMMU_HELPER 949 select SWIOTLB 950 depends on X86_64 && PCI && AMD_NB 951 help 952 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 953 GART based hardware IOMMUs. 954 955 The GART supports full DMA access for devices with 32-bit access 956 limitations, on systems with more than 3 GB. This is usually needed 957 for USB, sound, many IDE/SATA chipsets and some other devices. 958 959 Newer systems typically have a modern AMD IOMMU, supported via 960 the CONFIG_AMD_IOMMU=y config option. 961 962 In normal configurations this driver is only active when needed: 963 there's more than 3 GB of memory and the system contains a 964 32-bit limited device. 965 966 If unsure, say Y. 967 968config BOOT_VESA_SUPPORT 969 bool 970 help 971 If true, at least one selected framebuffer driver can take advantage 972 of VESA video modes set at an early boot stage via the vga= parameter. 973 974config MAXSMP 975 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 976 depends on X86_64 && SMP && DEBUG_KERNEL 977 select CPUMASK_OFFSTACK 978 help 979 Enable maximum number of CPUS and NUMA Nodes for this architecture. 980 If unsure, say N. 981 982# 983# The maximum number of CPUs supported: 984# 985# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 986# and which can be configured interactively in the 987# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 988# 989# The ranges are different on 32-bit and 64-bit kernels, depending on 990# hardware capabilities and scalability features of the kernel. 991# 992# ( If MAXSMP is enabled we just use the highest possible value and disable 993# interactive configuration. ) 994# 995 996config NR_CPUS_RANGE_BEGIN 997 int 998 default NR_CPUS_RANGE_END if MAXSMP 999 default 1 if !SMP 1000 default 2 1001 1002config NR_CPUS_RANGE_END 1003 int 1004 depends on X86_32 1005 default 8 if SMP 1006 default 1 if !SMP 1007 1008config NR_CPUS_RANGE_END 1009 int 1010 depends on X86_64 1011 default 8192 if SMP && CPUMASK_OFFSTACK 1012 default 512 if SMP && !CPUMASK_OFFSTACK 1013 default 1 if !SMP 1014 1015config NR_CPUS_DEFAULT 1016 int 1017 depends on X86_32 1018 default 8 if SMP 1019 default 1 if !SMP 1020 1021config NR_CPUS_DEFAULT 1022 int 1023 depends on X86_64 1024 default 8192 if MAXSMP 1025 default 64 if SMP 1026 default 1 if !SMP 1027 1028config NR_CPUS 1029 int "Maximum number of CPUs" if SMP && !MAXSMP 1030 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1031 default NR_CPUS_DEFAULT 1032 help 1033 This allows you to specify the maximum number of CPUs which this 1034 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1035 supported value is 8192, otherwise the maximum value is 512. The 1036 minimum value which makes sense is 2. 1037 1038 This is purely to save memory: each supported CPU adds about 8KB 1039 to the kernel image. 1040 1041config SCHED_CLUSTER 1042 bool "Cluster scheduler support" 1043 depends on SMP 1044 default y 1045 help 1046 Cluster scheduler support improves the CPU scheduler's decision 1047 making when dealing with machines that have clusters of CPUs. 1048 Cluster usually means a couple of CPUs which are placed closely 1049 by sharing mid-level caches, last-level cache tags or internal 1050 busses. 1051 1052config SCHED_SMT 1053 def_bool y if SMP 1054 1055config SCHED_MC 1056 def_bool y 1057 prompt "Multi-core scheduler support" 1058 depends on SMP 1059 help 1060 Multi-core scheduler support improves the CPU scheduler's decision 1061 making when dealing with multi-core CPU chips at a cost of slightly 1062 increased overhead in some places. If unsure say N here. 1063 1064config SCHED_MC_PRIO 1065 bool "CPU core priorities scheduler support" 1066 depends on SCHED_MC 1067 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1068 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1069 select CPU_FREQ 1070 default y 1071 help 1072 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1073 core ordering determined at manufacturing time, which allows 1074 certain cores to reach higher turbo frequencies (when running 1075 single threaded workloads) than others. 1076 1077 Enabling this kernel feature teaches the scheduler about 1078 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1079 scheduler's CPU selection logic accordingly, so that higher 1080 overall system performance can be achieved. 1081 1082 This feature will have no effect on CPUs without this feature. 1083 1084 If unsure say Y here. 1085 1086config UP_LATE_INIT 1087 def_bool y 1088 depends on !SMP && X86_LOCAL_APIC 1089 1090config X86_UP_APIC 1091 bool "Local APIC support on uniprocessors" if !PCI_MSI 1092 default PCI_MSI 1093 depends on X86_32 && !SMP 1094 help 1095 A local APIC (Advanced Programmable Interrupt Controller) is an 1096 integrated interrupt controller in the CPU. If you have a single-CPU 1097 system which has a processor with a local APIC, you can say Y here to 1098 enable and use it. If you say Y here even though your machine doesn't 1099 have a local APIC, then the kernel will still run with no slowdown at 1100 all. The local APIC supports CPU-generated self-interrupts (timer, 1101 performance counters), and the NMI watchdog which detects hard 1102 lockups. 1103 1104config X86_UP_IOAPIC 1105 bool "IO-APIC support on uniprocessors" 1106 depends on X86_UP_APIC 1107 help 1108 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1109 SMP-capable replacement for PC-style interrupt controllers. Most 1110 SMP systems and many recent uniprocessor systems have one. 1111 1112 If you have a single-CPU system with an IO-APIC, you can say Y here 1113 to use it. If you say Y here even though your machine doesn't have 1114 an IO-APIC, then the kernel will still run with no slowdown at all. 1115 1116config X86_LOCAL_APIC 1117 def_bool y 1118 depends on X86_64 || SMP || X86_UP_APIC || PCI_MSI 1119 select IRQ_DOMAIN_HIERARCHY 1120 1121config ACPI_MADT_WAKEUP 1122 def_bool y 1123 depends on X86_64 1124 depends on ACPI 1125 depends on SMP 1126 depends on X86_LOCAL_APIC 1127 1128config X86_IO_APIC 1129 def_bool y 1130 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1131 1132config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1133 bool "Reroute for broken boot IRQs" 1134 depends on X86_IO_APIC 1135 help 1136 This option enables a workaround that fixes a source of 1137 spurious interrupts. This is recommended when threaded 1138 interrupt handling is used on systems where the generation of 1139 superfluous "boot interrupts" cannot be disabled. 1140 1141 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1142 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1143 kernel does during interrupt handling). On chipsets where this 1144 boot IRQ generation cannot be disabled, this workaround keeps 1145 the original IRQ line masked so that only the equivalent "boot 1146 IRQ" is delivered to the CPUs. The workaround also tells the 1147 kernel to set up the IRQ handler on the boot IRQ line. In this 1148 way only one interrupt is delivered to the kernel. Otherwise 1149 the spurious second interrupt may cause the kernel to bring 1150 down (vital) interrupt lines. 1151 1152 Only affects "broken" chipsets. Interrupt sharing may be 1153 increased on these systems. 1154 1155config X86_MCE 1156 bool "Machine Check / overheating reporting" 1157 select GENERIC_ALLOCATOR 1158 default y 1159 help 1160 Machine Check support allows the processor to notify the 1161 kernel if it detects a problem (e.g. overheating, data corruption). 1162 The action the kernel takes depends on the severity of the problem, 1163 ranging from warning messages to halting the machine. 1164 1165config X86_MCELOG_LEGACY 1166 bool "Support for deprecated /dev/mcelog character device" 1167 depends on X86_MCE 1168 help 1169 Enable support for /dev/mcelog which is needed by the old mcelog 1170 userspace logging daemon. Consider switching to the new generation 1171 rasdaemon solution. 1172 1173config X86_MCE_INTEL 1174 def_bool y 1175 prompt "Intel MCE features" 1176 depends on X86_MCE && X86_LOCAL_APIC 1177 help 1178 Additional support for intel specific MCE features such as 1179 the thermal monitor. 1180 1181config X86_MCE_AMD 1182 def_bool y 1183 prompt "AMD MCE features" 1184 depends on X86_MCE && X86_LOCAL_APIC 1185 help 1186 Additional support for AMD specific MCE features such as 1187 the DRAM Error Threshold. 1188 1189config X86_ANCIENT_MCE 1190 bool "Support for old Pentium 5 / WinChip machine checks" 1191 depends on X86_32 && X86_MCE 1192 help 1193 Include support for machine check handling on old Pentium 5 or WinChip 1194 systems. These typically need to be enabled explicitly on the command 1195 line. 1196 1197config X86_MCE_THRESHOLD 1198 depends on X86_MCE_AMD || X86_MCE_INTEL 1199 def_bool y 1200 1201config X86_MCE_INJECT 1202 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1203 tristate "Machine check injector support" 1204 help 1205 Provide support for injecting machine checks for testing purposes. 1206 If you don't know what a machine check is and you don't do kernel 1207 QA it is safe to say n. 1208 1209source "arch/x86/events/Kconfig" 1210 1211config X86_LEGACY_VM86 1212 bool "Legacy VM86 support" 1213 depends on X86_32 1214 help 1215 This option allows user programs to put the CPU into V8086 1216 mode, which is an 80286-era approximation of 16-bit real mode. 1217 1218 Some very old versions of X and/or vbetool require this option 1219 for user mode setting. Similarly, DOSEMU will use it if 1220 available to accelerate real mode DOS programs. However, any 1221 recent version of DOSEMU, X, or vbetool should be fully 1222 functional even without kernel VM86 support, as they will all 1223 fall back to software emulation. Nevertheless, if you are using 1224 a 16-bit DOS program where 16-bit performance matters, vm86 1225 mode might be faster than emulation and you might want to 1226 enable this option. 1227 1228 Note that any app that works on a 64-bit kernel is unlikely to 1229 need this option, as 64-bit kernels don't, and can't, support 1230 V8086 mode. This option is also unrelated to 16-bit protected 1231 mode and is not needed to run most 16-bit programs under Wine. 1232 1233 Enabling this option increases the complexity of the kernel 1234 and slows down exception handling a tiny bit. 1235 1236 If unsure, say N here. 1237 1238config VM86 1239 bool 1240 default X86_LEGACY_VM86 1241 1242config X86_16BIT 1243 bool "Enable support for 16-bit segments" if EXPERT 1244 default y 1245 depends on MODIFY_LDT_SYSCALL 1246 help 1247 This option is required by programs like Wine to run 16-bit 1248 protected mode legacy code on x86 processors. Disabling 1249 this option saves about 300 bytes on i386, or around 6K text 1250 plus 16K runtime memory on x86-64, 1251 1252config X86_ESPFIX32 1253 def_bool y 1254 depends on X86_16BIT && X86_32 1255 1256config X86_ESPFIX64 1257 def_bool y 1258 depends on X86_16BIT && X86_64 1259 1260config X86_VSYSCALL_EMULATION 1261 bool "Enable vsyscall emulation" if EXPERT 1262 default y 1263 depends on X86_64 1264 help 1265 This enables emulation of the legacy vsyscall page. Disabling 1266 it is roughly equivalent to booting with vsyscall=none, except 1267 that it will also disable the helpful warning if a program 1268 tries to use a vsyscall. With this option set to N, offending 1269 programs will just segfault, citing addresses of the form 1270 0xffffffffff600?00. 1271 1272 This option is required by many programs built before 2013, and 1273 care should be used even with newer programs if set to N. 1274 1275 Disabling this option saves about 7K of kernel size and 1276 possibly 4K of additional runtime pagetable memory. 1277 1278config X86_IOPL_IOPERM 1279 bool "IOPERM and IOPL Emulation" 1280 default y 1281 help 1282 This enables the ioperm() and iopl() syscalls which are necessary 1283 for legacy applications. 1284 1285 Legacy IOPL support is an overbroad mechanism which allows user 1286 space aside of accessing all 65536 I/O ports also to disable 1287 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1288 capabilities and permission from potentially active security 1289 modules. 1290 1291 The emulation restricts the functionality of the syscall to 1292 only allowing the full range I/O port access, but prevents the 1293 ability to disable interrupts from user space which would be 1294 granted if the hardware IOPL mechanism would be used. 1295 1296config TOSHIBA 1297 tristate "Toshiba Laptop support" 1298 depends on X86_32 1299 help 1300 This adds a driver to safely access the System Management Mode of 1301 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1302 not work on models with a Phoenix BIOS. The System Management Mode 1303 is used to set the BIOS and power saving options on Toshiba portables. 1304 1305 For information on utilities to make use of this driver see the 1306 Toshiba Linux utilities web site at: 1307 <http://www.buzzard.org.uk/toshiba/>. 1308 1309 Say Y if you intend to run this kernel on a Toshiba portable. 1310 Say N otherwise. 1311 1312config X86_REBOOTFIXUPS 1313 bool "Enable X86 board specific fixups for reboot" 1314 depends on X86_32 1315 help 1316 This enables chipset and/or board specific fixups to be done 1317 in order to get reboot to work correctly. This is only needed on 1318 some combinations of hardware and BIOS. The symptom, for which 1319 this config is intended, is when reboot ends with a stalled/hung 1320 system. 1321 1322 Currently, the only fixup is for the Geode machines using 1323 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1324 1325 Say Y if you want to enable the fixup. Currently, it's safe to 1326 enable this option even if you don't need it. 1327 Say N otherwise. 1328 1329config MICROCODE 1330 def_bool y 1331 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1332 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD 1333 1334config MICROCODE_INITRD32 1335 def_bool y 1336 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1337 1338config MICROCODE_LATE_LOADING 1339 bool "Late microcode loading (DANGEROUS)" 1340 default n 1341 depends on MICROCODE && SMP 1342 help 1343 Loading microcode late, when the system is up and executing instructions 1344 is a tricky business and should be avoided if possible. Just the sequence 1345 of synchronizing all cores and SMT threads is one fragile dance which does 1346 not guarantee that cores might not softlock after the loading. Therefore, 1347 use this at your own risk. Late loading taints the kernel unless the 1348 microcode header indicates that it is safe for late loading via the 1349 minimal revision check. This minimal revision check can be enforced on 1350 the kernel command line with "microcode.minrev=Y". 1351 1352config MICROCODE_LATE_FORCE_MINREV 1353 bool "Enforce late microcode loading minimal revision check" 1354 default n 1355 depends on MICROCODE_LATE_LOADING 1356 help 1357 To prevent that users load microcode late which modifies already 1358 in use features, newer microcode patches have a minimum revision field 1359 in the microcode header, which tells the kernel which minimum 1360 revision must be active in the CPU to safely load that new microcode 1361 late into the running system. If disabled the check will not 1362 be enforced but the kernel will be tainted when the minimal 1363 revision check fails. 1364 1365 This minimal revision check can also be controlled via the 1366 "microcode.minrev" parameter on the kernel command line. 1367 1368 If unsure say Y. 1369 1370config X86_MSR 1371 tristate "/dev/cpu/*/msr - Model-specific register support" 1372 help 1373 This device gives privileged processes access to the x86 1374 Model-Specific Registers (MSRs). It is a character device with 1375 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1376 MSR accesses are directed to a specific CPU on multi-processor 1377 systems. 1378 1379config X86_CPUID 1380 tristate "/dev/cpu/*/cpuid - CPU information support" 1381 help 1382 This device gives processes access to the x86 CPUID instruction to 1383 be executed on a specific processor. It is a character device 1384 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1385 /dev/cpu/31/cpuid. 1386 1387config HIGHMEM4G 1388 bool "High Memory Support" 1389 depends on X86_32 1390 help 1391 Linux can use up to 4 Gigabytes of physical memory on x86 systems. 1392 However, the address space of 32-bit x86 processors is only 4 1393 Gigabytes large. That means that, if you have a large amount of 1394 physical memory, not all of it can be "permanently mapped" by the 1395 kernel. The physical memory that's not permanently mapped is called 1396 "high memory". 1397 1398 If you are compiling a kernel which will never run on a machine with 1399 more than 1 Gigabyte total physical RAM, answer "off" here (default 1400 choice and suitable for most users). This will result in a "3GB/1GB" 1401 split: 3GB are mapped so that each process sees a 3GB virtual memory 1402 space and the remaining part of the 4GB virtual memory space is used 1403 by the kernel to permanently map as much physical memory as 1404 possible. 1405 1406 If the machine has between 1 and 4 Gigabytes physical RAM, then 1407 answer "Y" here. 1408 1409 If unsure, say N. 1410 1411choice 1412 prompt "Memory split" if EXPERT 1413 default VMSPLIT_3G 1414 depends on X86_32 1415 help 1416 Select the desired split between kernel and user memory. 1417 1418 If the address range available to the kernel is less than the 1419 physical memory installed, the remaining memory will be available 1420 as "high memory". Accessing high memory is a little more costly 1421 than low memory, as it needs to be mapped into the kernel first. 1422 Note that increasing the kernel address space limits the range 1423 available to user programs, making the address space there 1424 tighter. Selecting anything other than the default 3G/1G split 1425 will also likely make your kernel incompatible with binary-only 1426 kernel modules. 1427 1428 If you are not absolutely sure what you are doing, leave this 1429 option alone! 1430 1431 config VMSPLIT_3G 1432 bool "3G/1G user/kernel split" 1433 config VMSPLIT_3G_OPT 1434 depends on !X86_PAE 1435 bool "3G/1G user/kernel split (for full 1G low memory)" 1436 config VMSPLIT_2G 1437 bool "2G/2G user/kernel split" 1438 config VMSPLIT_2G_OPT 1439 depends on !X86_PAE 1440 bool "2G/2G user/kernel split (for full 2G low memory)" 1441 config VMSPLIT_1G 1442 bool "1G/3G user/kernel split" 1443endchoice 1444 1445config PAGE_OFFSET 1446 hex 1447 default 0xB0000000 if VMSPLIT_3G_OPT 1448 default 0x80000000 if VMSPLIT_2G 1449 default 0x78000000 if VMSPLIT_2G_OPT 1450 default 0x40000000 if VMSPLIT_1G 1451 default 0xC0000000 1452 depends on X86_32 1453 1454config HIGHMEM 1455 def_bool HIGHMEM4G 1456 1457config X86_PAE 1458 bool "PAE (Physical Address Extension) Support" 1459 depends on X86_32 && X86_HAVE_PAE 1460 select PHYS_ADDR_T_64BIT 1461 help 1462 PAE is required for NX support, and furthermore enables 1463 larger swapspace support for non-overcommit purposes. It 1464 has the cost of more pagetable lookup overhead, and also 1465 consumes more pagetable space per process. 1466 1467config X86_DIRECT_GBPAGES 1468 def_bool y 1469 depends on X86_64 1470 help 1471 Certain kernel features effectively disable kernel 1472 linear 1 GB mappings (even if the CPU otherwise 1473 supports them), so don't confuse the user by printing 1474 that we have them enabled. 1475 1476config X86_CPA_STATISTICS 1477 bool "Enable statistic for Change Page Attribute" 1478 depends on DEBUG_FS 1479 help 1480 Expose statistics about the Change Page Attribute mechanism, which 1481 helps to determine the effectiveness of preserving large and huge 1482 page mappings when mapping protections are changed. 1483 1484config X86_MEM_ENCRYPT 1485 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1486 select DYNAMIC_PHYSICAL_MASK 1487 def_bool n 1488 1489config AMD_MEM_ENCRYPT 1490 bool "AMD Secure Memory Encryption (SME) support" 1491 depends on X86_64 && CPU_SUP_AMD 1492 depends on EFI_STUB 1493 select DMA_COHERENT_POOL 1494 select ARCH_USE_MEMREMAP_PROT 1495 select INSTRUCTION_DECODER 1496 select ARCH_HAS_CC_PLATFORM 1497 select X86_MEM_ENCRYPT 1498 select UNACCEPTED_MEMORY 1499 select CRYPTO_LIB_AESGCM 1500 help 1501 Say yes to enable support for the encryption of system memory. 1502 This requires an AMD processor that supports Secure Memory 1503 Encryption (SME). 1504 1505# Common NUMA Features 1506config NUMA 1507 bool "NUMA Memory Allocation and Scheduler Support" 1508 depends on SMP 1509 depends on X86_64 1510 select USE_PERCPU_NUMA_NODE_ID 1511 select OF_NUMA if OF 1512 help 1513 Enable NUMA (Non-Uniform Memory Access) support. 1514 1515 The kernel will try to allocate memory used by a CPU on the 1516 local memory controller of the CPU and add some more 1517 NUMA awareness to the kernel. 1518 1519 For 64-bit this is recommended if the system is Intel Core i7 1520 (or later), AMD Opteron, or EM64T NUMA. 1521 1522 Otherwise, you should say N. 1523 1524config AMD_NUMA 1525 def_bool y 1526 prompt "Old style AMD Opteron NUMA detection" 1527 depends on X86_64 && NUMA && PCI 1528 help 1529 Enable AMD NUMA node topology detection. You should say Y here if 1530 you have a multi processor AMD system. This uses an old method to 1531 read the NUMA configuration directly from the builtin Northbridge 1532 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1533 which also takes priority if both are compiled in. 1534 1535config X86_64_ACPI_NUMA 1536 def_bool y 1537 prompt "ACPI NUMA detection" 1538 depends on X86_64 && NUMA && ACPI && PCI 1539 select ACPI_NUMA 1540 help 1541 Enable ACPI SRAT based node topology detection. 1542 1543config NODES_SHIFT 1544 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1545 range 1 10 1546 default "10" if MAXSMP 1547 default "6" if X86_64 1548 default "3" 1549 depends on NUMA 1550 help 1551 Specify the maximum number of NUMA Nodes available on the target 1552 system. Increases memory reserved to accommodate various tables. 1553 1554config ARCH_FLATMEM_ENABLE 1555 def_bool y 1556 depends on X86_32 && !NUMA 1557 1558config ARCH_SPARSEMEM_ENABLE 1559 def_bool y 1560 select SPARSEMEM_STATIC if X86_32 1561 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1562 select SPARSEMEM_VMEMMAP if X86_64 1563 1564config ARCH_SPARSEMEM_DEFAULT 1565 def_bool X86_64 || (NUMA && X86_32) 1566 1567config ARCH_SELECT_MEMORY_MODEL 1568 def_bool y 1569 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1570 1571config ARCH_MEMORY_PROBE 1572 bool "Enable sysfs memory/probe interface" 1573 depends on MEMORY_HOTPLUG 1574 help 1575 This option enables a sysfs memory/probe interface for testing. 1576 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1577 If you are unsure how to answer this question, answer N. 1578 1579config ARCH_PROC_KCORE_TEXT 1580 def_bool y 1581 depends on X86_64 && PROC_KCORE 1582 1583config ILLEGAL_POINTER_VALUE 1584 hex 1585 default 0 if X86_32 1586 default 0xdead000000000000 if X86_64 1587 1588config X86_PMEM_LEGACY_DEVICE 1589 bool 1590 1591config X86_PMEM_LEGACY 1592 tristate "Support non-standard NVDIMMs and ADR protected memory" 1593 depends on PHYS_ADDR_T_64BIT 1594 depends on BLK_DEV 1595 select X86_PMEM_LEGACY_DEVICE 1596 select NUMA_KEEP_MEMINFO if NUMA 1597 select LIBNVDIMM 1598 help 1599 Treat memory marked using the non-standard e820 type of 12 as used 1600 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1601 The kernel will offer these regions to the 'pmem' driver so 1602 they can be used for persistent storage. 1603 1604 Say Y if unsure. 1605 1606config X86_CHECK_BIOS_CORRUPTION 1607 bool "Check for low memory corruption" 1608 help 1609 Periodically check for memory corruption in low memory, which 1610 is suspected to be caused by BIOS. Even when enabled in the 1611 configuration, it is disabled at runtime. Enable it by 1612 setting "memory_corruption_check=1" on the kernel command 1613 line. By default it scans the low 64k of memory every 60 1614 seconds; see the memory_corruption_check_size and 1615 memory_corruption_check_period parameters in 1616 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1617 1618 When enabled with the default parameters, this option has 1619 almost no overhead, as it reserves a relatively small amount 1620 of memory and scans it infrequently. It both detects corruption 1621 and prevents it from affecting the running system. 1622 1623 It is, however, intended as a diagnostic tool; if repeatable 1624 BIOS-originated corruption always affects the same memory, 1625 you can use memmap= to prevent the kernel from using that 1626 memory. 1627 1628config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1629 bool "Set the default setting of memory_corruption_check" 1630 depends on X86_CHECK_BIOS_CORRUPTION 1631 default y 1632 help 1633 Set whether the default state of memory_corruption_check is 1634 on or off. 1635 1636config MATH_EMULATION 1637 bool 1638 depends on MODIFY_LDT_SYSCALL 1639 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1640 help 1641 Linux can emulate a math coprocessor (used for floating point 1642 operations) if you don't have one. 486DX and Pentium processors have 1643 a math coprocessor built in, 486SX and 386 do not, unless you added 1644 a 487DX or 387, respectively. (The messages during boot time can 1645 give you some hints here ["man dmesg"].) Everyone needs either a 1646 coprocessor or this emulation. 1647 1648 If you don't have a math coprocessor, you need to say Y here; if you 1649 say Y here even though you have a coprocessor, the coprocessor will 1650 be used nevertheless. (This behavior can be changed with the kernel 1651 command line option "no387", which comes handy if your coprocessor 1652 is broken. Try "man bootparam" or see the documentation of your boot 1653 loader (lilo or loadlin) about how to pass options to the kernel at 1654 boot time.) This means that it is a good idea to say Y here if you 1655 intend to use this kernel on different machines. 1656 1657 More information about the internals of the Linux math coprocessor 1658 emulation can be found in <file:arch/x86/math-emu/README>. 1659 1660 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1661 kernel, it won't hurt. 1662 1663config MTRR 1664 def_bool y 1665 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1666 help 1667 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1668 the Memory Type Range Registers (MTRRs) may be used to control 1669 processor access to memory ranges. This is most useful if you have 1670 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1671 allows bus write transfers to be combined into a larger transfer 1672 before bursting over the PCI/AGP bus. This can increase performance 1673 of image write operations 2.5 times or more. Saying Y here creates a 1674 /proc/mtrr file which may be used to manipulate your processor's 1675 MTRRs. Typically the X server should use this. 1676 1677 This code has a reasonably generic interface so that similar 1678 control registers on other processors can be easily supported 1679 as well: 1680 1681 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1682 Registers (ARRs) which provide a similar functionality to MTRRs. For 1683 these, the ARRs are used to emulate the MTRRs. 1684 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1685 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1686 write-combining. All of these processors are supported by this code 1687 and it makes sense to say Y here if you have one of them. 1688 1689 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1690 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1691 can lead to all sorts of problems, so it's good to say Y here. 1692 1693 You can safely say Y even if your machine doesn't have MTRRs, you'll 1694 just add about 9 KB to your kernel. 1695 1696 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1697 1698config MTRR_SANITIZER 1699 def_bool y 1700 prompt "MTRR cleanup support" 1701 depends on MTRR 1702 help 1703 Convert MTRR layout from continuous to discrete, so X drivers can 1704 add writeback entries. 1705 1706 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1707 The largest mtrr entry size for a continuous block can be set with 1708 mtrr_chunk_size. 1709 1710 If unsure, say Y. 1711 1712config MTRR_SANITIZER_ENABLE_DEFAULT 1713 int "MTRR cleanup enable value (0-1)" 1714 range 0 1 1715 default "0" 1716 depends on MTRR_SANITIZER 1717 help 1718 Enable mtrr cleanup default value 1719 1720config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1721 int "MTRR cleanup spare reg num (0-7)" 1722 range 0 7 1723 default "1" 1724 depends on MTRR_SANITIZER 1725 help 1726 mtrr cleanup spare entries default, it can be changed via 1727 mtrr_spare_reg_nr=N on the kernel command line. 1728 1729config X86_PAT 1730 def_bool y 1731 prompt "x86 PAT support" if EXPERT 1732 depends on MTRR 1733 select ARCH_USES_PG_ARCH_2 1734 help 1735 Use PAT attributes to setup page level cache control. 1736 1737 PATs are the modern equivalents of MTRRs and are much more 1738 flexible than MTRRs. 1739 1740 Say N here if you see bootup problems (boot crash, boot hang, 1741 spontaneous reboots) or a non-working video driver. 1742 1743 If unsure, say Y. 1744 1745config X86_UMIP 1746 def_bool y 1747 prompt "User Mode Instruction Prevention" if EXPERT 1748 help 1749 User Mode Instruction Prevention (UMIP) is a security feature in 1750 some x86 processors. If enabled, a general protection fault is 1751 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1752 executed in user mode. These instructions unnecessarily expose 1753 information about the hardware state. 1754 1755 The vast majority of applications do not use these instructions. 1756 For the very few that do, software emulation is provided in 1757 specific cases in protected and virtual-8086 modes. Emulated 1758 results are dummy. 1759 1760config CC_HAS_IBT 1761 # GCC >= 9 and binutils >= 2.29 1762 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1763 # Clang/LLVM >= 14 1764 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1765 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1766 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1767 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1768 $(as-instr,endbr64) 1769 1770config X86_CET 1771 def_bool n 1772 help 1773 CET features configured (Shadow stack or IBT) 1774 1775config X86_KERNEL_IBT 1776 prompt "Indirect Branch Tracking" 1777 def_bool y 1778 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1779 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1780 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1781 select OBJTOOL 1782 select X86_CET 1783 help 1784 Build the kernel with support for Indirect Branch Tracking, a 1785 hardware support course-grain forward-edge Control Flow Integrity 1786 protection. It enforces that all indirect calls must land on 1787 an ENDBR instruction, as such, the compiler will instrument the 1788 code with them to make this happen. 1789 1790 In addition to building the kernel with IBT, seal all functions that 1791 are not indirect call targets, avoiding them ever becoming one. 1792 1793 This requires LTO like objtool runs and will slow down the build. It 1794 does significantly reduce the number of ENDBR instructions in the 1795 kernel image. 1796 1797config X86_INTEL_MEMORY_PROTECTION_KEYS 1798 prompt "Memory Protection Keys" 1799 def_bool y 1800 # Note: only available in 64-bit mode 1801 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1802 select ARCH_USES_HIGH_VMA_FLAGS 1803 select ARCH_HAS_PKEYS 1804 help 1805 Memory Protection Keys provides a mechanism for enforcing 1806 page-based protections, but without requiring modification of the 1807 page tables when an application changes protection domains. 1808 1809 For details, see Documentation/core-api/protection-keys.rst 1810 1811 If unsure, say y. 1812 1813config ARCH_PKEY_BITS 1814 int 1815 default 4 1816 1817choice 1818 prompt "TSX enable mode" 1819 depends on CPU_SUP_INTEL 1820 default X86_INTEL_TSX_MODE_OFF 1821 help 1822 Intel's TSX (Transactional Synchronization Extensions) feature 1823 allows to optimize locking protocols through lock elision which 1824 can lead to a noticeable performance boost. 1825 1826 On the other hand it has been shown that TSX can be exploited 1827 to form side channel attacks (e.g. TAA) and chances are there 1828 will be more of those attacks discovered in the future. 1829 1830 Therefore TSX is not enabled by default (aka tsx=off). An admin 1831 might override this decision by tsx=on the command line parameter. 1832 Even with TSX enabled, the kernel will attempt to enable the best 1833 possible TAA mitigation setting depending on the microcode available 1834 for the particular machine. 1835 1836 This option allows to set the default tsx mode between tsx=on, =off 1837 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1838 details. 1839 1840 Say off if not sure, auto if TSX is in use but it should be used on safe 1841 platforms or on if TSX is in use and the security aspect of tsx is not 1842 relevant. 1843 1844config X86_INTEL_TSX_MODE_OFF 1845 bool "off" 1846 help 1847 TSX is disabled if possible - equals to tsx=off command line parameter. 1848 1849config X86_INTEL_TSX_MODE_ON 1850 bool "on" 1851 help 1852 TSX is always enabled on TSX capable HW - equals the tsx=on command 1853 line parameter. 1854 1855config X86_INTEL_TSX_MODE_AUTO 1856 bool "auto" 1857 help 1858 TSX is enabled on TSX capable HW that is believed to be safe against 1859 side channel attacks- equals the tsx=auto command line parameter. 1860endchoice 1861 1862config X86_SGX 1863 bool "Software Guard eXtensions (SGX)" 1864 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1865 depends on CRYPTO=y 1866 depends on CRYPTO_SHA256=y 1867 select MMU_NOTIFIER 1868 select NUMA_KEEP_MEMINFO if NUMA 1869 select XARRAY_MULTI 1870 help 1871 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1872 that can be used by applications to set aside private regions of code 1873 and data, referred to as enclaves. An enclave's private memory can 1874 only be accessed by code running within the enclave. Accesses from 1875 outside the enclave, including other enclaves, are disallowed by 1876 hardware. 1877 1878 If unsure, say N. 1879 1880config X86_USER_SHADOW_STACK 1881 bool "X86 userspace shadow stack" 1882 depends on AS_WRUSS 1883 depends on X86_64 1884 select ARCH_USES_HIGH_VMA_FLAGS 1885 select ARCH_HAS_USER_SHADOW_STACK 1886 select X86_CET 1887 help 1888 Shadow stack protection is a hardware feature that detects function 1889 return address corruption. This helps mitigate ROP attacks. 1890 Applications must be enabled to use it, and old userspace does not 1891 get protection "for free". 1892 1893 CPUs supporting shadow stacks were first released in 2020. 1894 1895 See Documentation/arch/x86/shstk.rst for more information. 1896 1897 If unsure, say N. 1898 1899config INTEL_TDX_HOST 1900 bool "Intel Trust Domain Extensions (TDX) host support" 1901 depends on CPU_SUP_INTEL 1902 depends on X86_64 1903 depends on KVM_INTEL 1904 depends on X86_X2APIC 1905 select ARCH_KEEP_MEMBLOCK 1906 depends on CONTIG_ALLOC 1907 depends on !KEXEC_CORE 1908 depends on X86_MCE 1909 help 1910 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1911 host and certain physical attacks. This option enables necessary TDX 1912 support in the host kernel to run confidential VMs. 1913 1914 If unsure, say N. 1915 1916config EFI 1917 bool "EFI runtime service support" 1918 depends on ACPI 1919 select UCS2_STRING 1920 select EFI_RUNTIME_WRAPPERS 1921 select ARCH_USE_MEMREMAP_PROT 1922 select EFI_RUNTIME_MAP if KEXEC_CORE 1923 help 1924 This enables the kernel to use EFI runtime services that are 1925 available (such as the EFI variable services). 1926 1927 This option is only useful on systems that have EFI firmware. 1928 In addition, you should use the latest ELILO loader available 1929 at <http://elilo.sourceforge.net> in order to take advantage 1930 of EFI runtime services. However, even with this option, the 1931 resultant kernel should continue to boot on existing non-EFI 1932 platforms. 1933 1934config EFI_STUB 1935 bool "EFI stub support" 1936 depends on EFI 1937 select RELOCATABLE 1938 help 1939 This kernel feature allows a bzImage to be loaded directly 1940 by EFI firmware without the use of a bootloader. 1941 1942 See Documentation/admin-guide/efi-stub.rst for more information. 1943 1944config EFI_HANDOVER_PROTOCOL 1945 bool "EFI handover protocol (DEPRECATED)" 1946 depends on EFI_STUB 1947 default y 1948 help 1949 Select this in order to include support for the deprecated EFI 1950 handover protocol, which defines alternative entry points into the 1951 EFI stub. This is a practice that has no basis in the UEFI 1952 specification, and requires a priori knowledge on the part of the 1953 bootloader about Linux/x86 specific ways of passing the command line 1954 and initrd, and where in memory those assets may be loaded. 1955 1956 If in doubt, say Y. Even though the corresponding support is not 1957 present in upstream GRUB or other bootloaders, most distros build 1958 GRUB with numerous downstream patches applied, and may rely on the 1959 handover protocol as as result. 1960 1961config EFI_MIXED 1962 bool "EFI mixed-mode support" 1963 depends on EFI_STUB && X86_64 1964 help 1965 Enabling this feature allows a 64-bit kernel to be booted 1966 on a 32-bit firmware, provided that your CPU supports 64-bit 1967 mode. 1968 1969 Note that it is not possible to boot a mixed-mode enabled 1970 kernel via the EFI boot stub - a bootloader that supports 1971 the EFI handover protocol must be used. 1972 1973 If unsure, say N. 1974 1975config EFI_RUNTIME_MAP 1976 bool "Export EFI runtime maps to sysfs" if EXPERT 1977 depends on EFI 1978 help 1979 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 1980 That memory map is required by the 2nd kernel to set up EFI virtual 1981 mappings after kexec, but can also be used for debugging purposes. 1982 1983 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 1984 1985source "kernel/Kconfig.hz" 1986 1987config ARCH_SUPPORTS_KEXEC 1988 def_bool y 1989 1990config ARCH_SUPPORTS_KEXEC_FILE 1991 def_bool X86_64 1992 1993config ARCH_SELECTS_KEXEC_FILE 1994 def_bool y 1995 depends on KEXEC_FILE 1996 select HAVE_IMA_KEXEC if IMA 1997 1998config ARCH_SUPPORTS_KEXEC_PURGATORY 1999 def_bool y 2000 2001config ARCH_SUPPORTS_KEXEC_SIG 2002 def_bool y 2003 2004config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2005 def_bool y 2006 2007config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2008 def_bool y 2009 2010config ARCH_SUPPORTS_KEXEC_JUMP 2011 def_bool y 2012 2013config ARCH_SUPPORTS_CRASH_DUMP 2014 def_bool X86_64 || (X86_32 && HIGHMEM) 2015 2016config ARCH_DEFAULT_CRASH_DUMP 2017 def_bool y 2018 2019config ARCH_SUPPORTS_CRASH_HOTPLUG 2020 def_bool y 2021 2022config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2023 def_bool CRASH_RESERVE 2024 2025config PHYSICAL_START 2026 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2027 default "0x1000000" 2028 help 2029 This gives the physical address where the kernel is loaded. 2030 2031 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2032 will decompress itself to above physical address and run from there. 2033 Otherwise, bzImage will run from the address where it has been loaded 2034 by the boot loader. The only exception is if it is loaded below the 2035 above physical address, in which case it will relocate itself there. 2036 2037 In normal kdump cases one does not have to set/change this option 2038 as now bzImage can be compiled as a completely relocatable image 2039 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2040 address. This option is mainly useful for the folks who don't want 2041 to use a bzImage for capturing the crash dump and want to use a 2042 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2043 to be specifically compiled to run from a specific memory area 2044 (normally a reserved region) and this option comes handy. 2045 2046 So if you are using bzImage for capturing the crash dump, 2047 leave the value here unchanged to 0x1000000 and set 2048 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2049 for capturing the crash dump change this value to start of 2050 the reserved region. In other words, it can be set based on 2051 the "X" value as specified in the "crashkernel=YM@XM" 2052 command line boot parameter passed to the panic-ed 2053 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2054 for more details about crash dumps. 2055 2056 Usage of bzImage for capturing the crash dump is recommended as 2057 one does not have to build two kernels. Same kernel can be used 2058 as production kernel and capture kernel. Above option should have 2059 gone away after relocatable bzImage support is introduced. But it 2060 is present because there are users out there who continue to use 2061 vmlinux for dump capture. This option should go away down the 2062 line. 2063 2064 Don't change this unless you know what you are doing. 2065 2066config RELOCATABLE 2067 bool "Build a relocatable kernel" 2068 default y 2069 help 2070 This builds a kernel image that retains relocation information 2071 so it can be loaded someplace besides the default 1MB. 2072 The relocations tend to make the kernel binary about 10% larger, 2073 but are discarded at runtime. 2074 2075 One use is for the kexec on panic case where the recovery kernel 2076 must live at a different physical address than the primary 2077 kernel. 2078 2079 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2080 it has been loaded at and the compile time physical address 2081 (CONFIG_PHYSICAL_START) is used as the minimum location. 2082 2083config RANDOMIZE_BASE 2084 bool "Randomize the address of the kernel image (KASLR)" 2085 depends on RELOCATABLE 2086 default y 2087 help 2088 In support of Kernel Address Space Layout Randomization (KASLR), 2089 this randomizes the physical address at which the kernel image 2090 is decompressed and the virtual address where the kernel 2091 image is mapped, as a security feature that deters exploit 2092 attempts relying on knowledge of the location of kernel 2093 code internals. 2094 2095 On 64-bit, the kernel physical and virtual addresses are 2096 randomized separately. The physical address will be anywhere 2097 between 16MB and the top of physical memory (up to 64TB). The 2098 virtual address will be randomized from 16MB up to 1GB (9 bits 2099 of entropy). Note that this also reduces the memory space 2100 available to kernel modules from 1.5GB to 1GB. 2101 2102 On 32-bit, the kernel physical and virtual addresses are 2103 randomized together. They will be randomized from 16MB up to 2104 512MB (8 bits of entropy). 2105 2106 Entropy is generated using the RDRAND instruction if it is 2107 supported. If RDTSC is supported, its value is mixed into 2108 the entropy pool as well. If neither RDRAND nor RDTSC are 2109 supported, then entropy is read from the i8254 timer. The 2110 usable entropy is limited by the kernel being built using 2111 2GB addressing, and that PHYSICAL_ALIGN must be at a 2112 minimum of 2MB. As a result, only 10 bits of entropy are 2113 theoretically possible, but the implementations are further 2114 limited due to memory layouts. 2115 2116 If unsure, say Y. 2117 2118# Relocation on x86 needs some additional build support 2119config X86_NEED_RELOCS 2120 def_bool y 2121 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2122 select ARCH_VMLINUX_NEEDS_RELOCS 2123 2124config PHYSICAL_ALIGN 2125 hex "Alignment value to which kernel should be aligned" 2126 default "0x200000" 2127 range 0x2000 0x1000000 if X86_32 2128 range 0x200000 0x1000000 if X86_64 2129 help 2130 This value puts the alignment restrictions on physical address 2131 where kernel is loaded and run from. Kernel is compiled for an 2132 address which meets above alignment restriction. 2133 2134 If bootloader loads the kernel at a non-aligned address and 2135 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2136 address aligned to above value and run from there. 2137 2138 If bootloader loads the kernel at a non-aligned address and 2139 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2140 load address and decompress itself to the address it has been 2141 compiled for and run from there. The address for which kernel is 2142 compiled already meets above alignment restrictions. Hence the 2143 end result is that kernel runs from a physical address meeting 2144 above alignment restrictions. 2145 2146 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2147 this value must be a multiple of 0x200000. 2148 2149 Don't change this unless you know what you are doing. 2150 2151config RANDOMIZE_MEMORY 2152 bool "Randomize the kernel memory sections" 2153 depends on X86_64 2154 depends on RANDOMIZE_BASE 2155 default RANDOMIZE_BASE 2156 help 2157 Randomizes the base virtual address of kernel memory sections 2158 (physical memory mapping, vmalloc & vmemmap). This security feature 2159 makes exploits relying on predictable memory locations less reliable. 2160 2161 The order of allocations remains unchanged. Entropy is generated in 2162 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2163 configuration have in average 30,000 different possible virtual 2164 addresses for each memory section. 2165 2166 If unsure, say Y. 2167 2168config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2169 hex "Physical memory mapping padding" if EXPERT 2170 depends on RANDOMIZE_MEMORY 2171 default "0xa" if MEMORY_HOTPLUG 2172 default "0x0" 2173 range 0x1 0x40 if MEMORY_HOTPLUG 2174 range 0x0 0x40 2175 help 2176 Define the padding in terabytes added to the existing physical 2177 memory size during kernel memory randomization. It is useful 2178 for memory hotplug support but reduces the entropy available for 2179 address randomization. 2180 2181 If unsure, leave at the default value. 2182 2183config ADDRESS_MASKING 2184 bool "Linear Address Masking support" 2185 depends on X86_64 2186 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2187 help 2188 Linear Address Masking (LAM) modifies the checking that is applied 2189 to 64-bit linear addresses, allowing software to use of the 2190 untranslated address bits for metadata. 2191 2192 The capability can be used for efficient address sanitizers (ASAN) 2193 implementation and for optimizations in JITs. 2194 2195config HOTPLUG_CPU 2196 def_bool y 2197 depends on SMP 2198 2199config COMPAT_VDSO 2200 def_bool n 2201 prompt "Workaround for glibc 2.3.2 / 2.3.3 (released in year 2003/2004)" 2202 depends on COMPAT_32 2203 help 2204 Certain buggy versions of glibc will crash if they are 2205 presented with a 32-bit vDSO that is not mapped at the address 2206 indicated in its segment table. 2207 2208 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2209 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2210 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2211 the only released version with the bug, but OpenSUSE 9 2212 contains a buggy "glibc 2.3.2". 2213 2214 The symptom of the bug is that everything crashes on startup, saying: 2215 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2216 2217 Saying Y here changes the default value of the vdso32 boot 2218 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2219 This works around the glibc bug but hurts performance. 2220 2221 If unsure, say N: if you are compiling your own kernel, you 2222 are unlikely to be using a buggy version of glibc. 2223 2224choice 2225 prompt "vsyscall table for legacy applications" 2226 depends on X86_64 2227 default LEGACY_VSYSCALL_XONLY 2228 help 2229 Legacy user code that does not know how to find the vDSO expects 2230 to be able to issue three syscalls by calling fixed addresses in 2231 kernel space. Since this location is not randomized with ASLR, 2232 it can be used to assist security vulnerability exploitation. 2233 2234 This setting can be changed at boot time via the kernel command 2235 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2236 is deprecated and can only be enabled using the kernel command 2237 line. 2238 2239 On a system with recent enough glibc (2.14 or newer) and no 2240 static binaries, you can say None without a performance penalty 2241 to improve security. 2242 2243 If unsure, select "Emulate execution only". 2244 2245 config LEGACY_VSYSCALL_XONLY 2246 bool "Emulate execution only" 2247 help 2248 The kernel traps and emulates calls into the fixed vsyscall 2249 address mapping and does not allow reads. This 2250 configuration is recommended when userspace might use the 2251 legacy vsyscall area but support for legacy binary 2252 instrumentation of legacy code is not needed. It mitigates 2253 certain uses of the vsyscall area as an ASLR-bypassing 2254 buffer. 2255 2256 config LEGACY_VSYSCALL_NONE 2257 bool "None" 2258 help 2259 There will be no vsyscall mapping at all. This will 2260 eliminate any risk of ASLR bypass due to the vsyscall 2261 fixed address mapping. Attempts to use the vsyscalls 2262 will be reported to dmesg, so that either old or 2263 malicious userspace programs can be identified. 2264 2265endchoice 2266 2267config CMDLINE_BOOL 2268 bool "Built-in kernel command line" 2269 help 2270 Allow for specifying boot arguments to the kernel at 2271 build time. On some systems (e.g. embedded ones), it is 2272 necessary or convenient to provide some or all of the 2273 kernel boot arguments with the kernel itself (that is, 2274 to not rely on the boot loader to provide them.) 2275 2276 To compile command line arguments into the kernel, 2277 set this option to 'Y', then fill in the 2278 boot arguments in CONFIG_CMDLINE. 2279 2280 Systems with fully functional boot loaders (i.e. non-embedded) 2281 should leave this option set to 'N'. 2282 2283config CMDLINE 2284 string "Built-in kernel command string" 2285 depends on CMDLINE_BOOL 2286 default "" 2287 help 2288 Enter arguments here that should be compiled into the kernel 2289 image and used at boot time. If the boot loader provides a 2290 command line at boot time, it is appended to this string to 2291 form the full kernel command line, when the system boots. 2292 2293 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2294 change this behavior. 2295 2296 In most cases, the command line (whether built-in or provided 2297 by the boot loader) should specify the device for the root 2298 file system. 2299 2300config CMDLINE_OVERRIDE 2301 bool "Built-in command line overrides boot loader arguments" 2302 depends on CMDLINE_BOOL && CMDLINE != "" 2303 help 2304 Set this option to 'Y' to have the kernel ignore the boot loader 2305 command line, and use ONLY the built-in command line. 2306 2307 This is used to work around broken boot loaders. This should 2308 be set to 'N' under normal conditions. 2309 2310config MODIFY_LDT_SYSCALL 2311 bool "Enable the LDT (local descriptor table)" if EXPERT 2312 default y 2313 help 2314 Linux can allow user programs to install a per-process x86 2315 Local Descriptor Table (LDT) using the modify_ldt(2) system 2316 call. This is required to run 16-bit or segmented code such as 2317 DOSEMU or some Wine programs. It is also used by some very old 2318 threading libraries. 2319 2320 Enabling this feature adds a small amount of overhead to 2321 context switches and increases the low-level kernel attack 2322 surface. Disabling it removes the modify_ldt(2) system call. 2323 2324 Saying 'N' here may make sense for embedded or server kernels. 2325 2326config STRICT_SIGALTSTACK_SIZE 2327 bool "Enforce strict size checking for sigaltstack" 2328 depends on DYNAMIC_SIGFRAME 2329 help 2330 For historical reasons MINSIGSTKSZ is a constant which became 2331 already too small with AVX512 support. Add a mechanism to 2332 enforce strict checking of the sigaltstack size against the 2333 real size of the FPU frame. This option enables the check 2334 by default. It can also be controlled via the kernel command 2335 line option 'strict_sas_size' independent of this config 2336 switch. Enabling it might break existing applications which 2337 allocate a too small sigaltstack but 'work' because they 2338 never get a signal delivered. 2339 2340 Say 'N' unless you want to really enforce this check. 2341 2342config CFI_AUTO_DEFAULT 2343 bool "Attempt to use FineIBT by default at boot time" 2344 depends on FINEIBT 2345 depends on !RUST || RUSTC_VERSION >= 108800 2346 default y 2347 help 2348 Attempt to use FineIBT by default at boot time. If enabled, 2349 this is the same as booting with "cfi=auto". If disabled, 2350 this is the same as booting with "cfi=kcfi". 2351 2352source "kernel/livepatch/Kconfig" 2353 2354config X86_BUS_LOCK_DETECT 2355 bool "Split Lock Detect and Bus Lock Detect support" 2356 depends on CPU_SUP_INTEL || CPU_SUP_AMD 2357 default y 2358 help 2359 Enable Split Lock Detect and Bus Lock Detect functionalities. 2360 See <file:Documentation/arch/x86/buslock.rst> for more information. 2361 2362endmenu 2363 2364config CC_HAS_NAMED_AS 2365 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null) 2366 depends on CC_IS_GCC 2367 2368# 2369# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN) 2370# are incompatible with named address spaces with GCC < 13.3 2371# (see GCC PR sanitizer/111736 and also PR sanitizer/115172). 2372# 2373 2374config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2375 def_bool y 2376 depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300 2377 depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200 2378 2379config USE_X86_SEG_SUPPORT 2380 def_bool CC_HAS_NAMED_AS 2381 depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS 2382 2383config CC_HAS_SLS 2384 def_bool $(cc-option,-mharden-sls=all) 2385 2386config CC_HAS_RETURN_THUNK 2387 def_bool $(cc-option,-mfunction-return=thunk-extern) 2388 2389config CC_HAS_ENTRY_PADDING 2390 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2391 2392config CC_HAS_KCFI_ARITY 2393 def_bool $(cc-option,-fsanitize=kcfi -fsanitize-kcfi-arity) 2394 depends on CC_IS_CLANG && !RUST 2395 2396config FUNCTION_PADDING_CFI 2397 int 2398 default 59 if FUNCTION_ALIGNMENT_64B 2399 default 27 if FUNCTION_ALIGNMENT_32B 2400 default 11 if FUNCTION_ALIGNMENT_16B 2401 default 3 if FUNCTION_ALIGNMENT_8B 2402 default 0 2403 2404# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2405# except Kconfig can't do arithmetic :/ 2406config FUNCTION_PADDING_BYTES 2407 int 2408 default FUNCTION_PADDING_CFI if CFI_CLANG 2409 default FUNCTION_ALIGNMENT 2410 2411config CALL_PADDING 2412 def_bool n 2413 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2414 select FUNCTION_ALIGNMENT_16B 2415 2416config FINEIBT 2417 def_bool y 2418 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE 2419 select CALL_PADDING 2420 2421config FINEIBT_BHI 2422 def_bool y 2423 depends on FINEIBT && CC_HAS_KCFI_ARITY 2424 2425config HAVE_CALL_THUNKS 2426 def_bool y 2427 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2428 2429config CALL_THUNKS 2430 def_bool n 2431 select CALL_PADDING 2432 2433config PREFIX_SYMBOLS 2434 def_bool y 2435 depends on CALL_PADDING && !CFI_CLANG 2436 2437menuconfig CPU_MITIGATIONS 2438 bool "Mitigations for CPU vulnerabilities" 2439 default y 2440 help 2441 Say Y here to enable options which enable mitigations for hardware 2442 vulnerabilities (usually related to speculative execution). 2443 Mitigations can be disabled or restricted to SMT systems at runtime 2444 via the "mitigations" kernel parameter. 2445 2446 If you say N, all mitigations will be disabled. This CANNOT be 2447 overridden at runtime. 2448 2449 Say 'Y', unless you really know what you are doing. 2450 2451if CPU_MITIGATIONS 2452 2453config MITIGATION_PAGE_TABLE_ISOLATION 2454 bool "Remove the kernel mapping in user mode" 2455 default y 2456 depends on (X86_64 || X86_PAE) 2457 help 2458 This feature reduces the number of hardware side channels by 2459 ensuring that the majority of kernel addresses are not mapped 2460 into userspace. 2461 2462 See Documentation/arch/x86/pti.rst for more details. 2463 2464config MITIGATION_RETPOLINE 2465 bool "Avoid speculative indirect branches in kernel" 2466 select OBJTOOL if HAVE_OBJTOOL 2467 default y 2468 help 2469 Compile kernel with the retpoline compiler options to guard against 2470 kernel-to-user data leaks by avoiding speculative indirect 2471 branches. Requires a compiler with -mindirect-branch=thunk-extern 2472 support for full protection. The kernel may run slower. 2473 2474config MITIGATION_RETHUNK 2475 bool "Enable return-thunks" 2476 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2477 select OBJTOOL if HAVE_OBJTOOL 2478 default y if X86_64 2479 help 2480 Compile the kernel with the return-thunks compiler option to guard 2481 against kernel-to-user data leaks by avoiding return speculation. 2482 Requires a compiler with -mfunction-return=thunk-extern 2483 support for full protection. The kernel may run slower. 2484 2485config MITIGATION_UNRET_ENTRY 2486 bool "Enable UNRET on kernel entry" 2487 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2488 default y 2489 help 2490 Compile the kernel with support for the retbleed=unret mitigation. 2491 2492config MITIGATION_CALL_DEPTH_TRACKING 2493 bool "Mitigate RSB underflow with call depth tracking" 2494 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2495 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2496 select CALL_THUNKS 2497 default y 2498 help 2499 Compile the kernel with call depth tracking to mitigate the Intel 2500 SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off 2501 by default and needs to be enabled on the kernel command line via the 2502 retbleed=stuff option. For non-affected systems the overhead of this 2503 option is marginal as the call depth tracking is using run-time 2504 generated call thunks in a compiler generated padding area and call 2505 patching. This increases text size by ~5%. For non affected systems 2506 this space is unused. On affected SKL systems this results in a 2507 significant performance gain over the IBRS mitigation. 2508 2509config CALL_THUNKS_DEBUG 2510 bool "Enable call thunks and call depth tracking debugging" 2511 depends on MITIGATION_CALL_DEPTH_TRACKING 2512 select FUNCTION_ALIGNMENT_32B 2513 default n 2514 help 2515 Enable call/ret counters for imbalance detection and build in 2516 a noisy dmesg about callthunks generation and call patching for 2517 trouble shooting. The debug prints need to be enabled on the 2518 kernel command line with 'debug-callthunks'. 2519 Only enable this when you are debugging call thunks as this 2520 creates a noticeable runtime overhead. If unsure say N. 2521 2522config MITIGATION_IBPB_ENTRY 2523 bool "Enable IBPB on kernel entry" 2524 depends on CPU_SUP_AMD && X86_64 2525 default y 2526 help 2527 Compile the kernel with support for the retbleed=ibpb and 2528 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations. 2529 2530config MITIGATION_IBRS_ENTRY 2531 bool "Enable IBRS on kernel entry" 2532 depends on CPU_SUP_INTEL && X86_64 2533 default y 2534 help 2535 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2536 This mitigates both spectre_v2 and retbleed at great cost to 2537 performance. 2538 2539config MITIGATION_SRSO 2540 bool "Mitigate speculative RAS overflow on AMD" 2541 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2542 default y 2543 help 2544 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2545 2546config MITIGATION_SLS 2547 bool "Mitigate Straight-Line-Speculation" 2548 depends on CC_HAS_SLS && X86_64 2549 select OBJTOOL if HAVE_OBJTOOL 2550 default n 2551 help 2552 Compile the kernel with straight-line-speculation options to guard 2553 against straight line speculation. The kernel image might be slightly 2554 larger. 2555 2556config MITIGATION_GDS 2557 bool "Mitigate Gather Data Sampling" 2558 depends on CPU_SUP_INTEL 2559 default y 2560 help 2561 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware 2562 vulnerability which allows unprivileged speculative access to data 2563 which was previously stored in vector registers. The attacker uses gather 2564 instructions to infer the stale vector register data. 2565 2566config MITIGATION_RFDS 2567 bool "RFDS Mitigation" 2568 depends on CPU_SUP_INTEL 2569 default y 2570 help 2571 Enable mitigation for Register File Data Sampling (RFDS) by default. 2572 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2573 allows unprivileged speculative access to stale data previously 2574 stored in floating point, vector and integer registers. 2575 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2576 2577config MITIGATION_SPECTRE_BHI 2578 bool "Mitigate Spectre-BHB (Branch History Injection)" 2579 depends on CPU_SUP_INTEL 2580 default y 2581 help 2582 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2583 where the branch history buffer is poisoned to speculatively steer 2584 indirect branches. 2585 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2586 2587config MITIGATION_MDS 2588 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug" 2589 depends on CPU_SUP_INTEL 2590 default y 2591 help 2592 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is 2593 a hardware vulnerability which allows unprivileged speculative access 2594 to data which is available in various CPU internal buffers. 2595 See also <file:Documentation/admin-guide/hw-vuln/mds.rst> 2596 2597config MITIGATION_TAA 2598 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug" 2599 depends on CPU_SUP_INTEL 2600 default y 2601 help 2602 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware 2603 vulnerability that allows unprivileged speculative access to data 2604 which is available in various CPU internal buffers by using 2605 asynchronous aborts within an Intel TSX transactional region. 2606 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst> 2607 2608config MITIGATION_MMIO_STALE_DATA 2609 bool "Mitigate MMIO Stale Data hardware bug" 2610 depends on CPU_SUP_INTEL 2611 default y 2612 help 2613 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO 2614 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO) 2615 vulnerabilities that can expose data. The vulnerabilities require the 2616 attacker to have access to MMIO. 2617 See also 2618 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst> 2619 2620config MITIGATION_L1TF 2621 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug" 2622 depends on CPU_SUP_INTEL 2623 default y 2624 help 2625 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a 2626 hardware vulnerability which allows unprivileged speculative access to data 2627 available in the Level 1 Data Cache. 2628 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst 2629 2630config MITIGATION_RETBLEED 2631 bool "Mitigate RETBleed hardware bug" 2632 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY 2633 default y 2634 help 2635 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution 2636 with Return Instructions) vulnerability. RETBleed is a speculative 2637 execution attack which takes advantage of microarchitectural behavior 2638 in many modern microprocessors, similar to Spectre v2. An 2639 unprivileged attacker can use these flaws to bypass conventional 2640 memory security restrictions to gain read access to privileged memory 2641 that would otherwise be inaccessible. 2642 2643config MITIGATION_SPECTRE_V1 2644 bool "Mitigate SPECTRE V1 hardware bug" 2645 default y 2646 help 2647 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a 2648 class of side channel attacks that takes advantage of speculative 2649 execution that bypasses conditional branch instructions used for 2650 memory access bounds check. 2651 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2652 2653config MITIGATION_SPECTRE_V2 2654 bool "Mitigate SPECTRE V2 hardware bug" 2655 default y 2656 help 2657 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre 2658 V2 is a class of side channel attacks that takes advantage of 2659 indirect branch predictors inside the processor. In Spectre variant 2 2660 attacks, the attacker can steer speculative indirect branches in the 2661 victim to gadget code by poisoning the branch target buffer of a CPU 2662 used for predicting indirect branch addresses. 2663 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2664 2665config MITIGATION_SRBDS 2666 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug" 2667 depends on CPU_SUP_INTEL 2668 default y 2669 help 2670 Enable mitigation for Special Register Buffer Data Sampling (SRBDS). 2671 SRBDS is a hardware vulnerability that allows Microarchitectural Data 2672 Sampling (MDS) techniques to infer values returned from special 2673 register accesses. An unprivileged user can extract values returned 2674 from RDRAND and RDSEED executed on another core or sibling thread 2675 using MDS techniques. 2676 See also 2677 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst> 2678 2679config MITIGATION_SSB 2680 bool "Mitigate Speculative Store Bypass (SSB) hardware bug" 2681 default y 2682 help 2683 Enable mitigation for Speculative Store Bypass (SSB). SSB is a 2684 hardware security vulnerability and its exploitation takes advantage 2685 of speculative execution in a similar way to the Meltdown and Spectre 2686 security vulnerabilities. 2687 2688config MITIGATION_ITS 2689 bool "Enable Indirect Target Selection mitigation" 2690 depends on CPU_SUP_INTEL && X86_64 2691 depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK 2692 select EXECMEM 2693 default y 2694 help 2695 Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in 2696 BPU on some Intel CPUs that may allow Spectre V2 style attacks. If 2697 disabled, mitigation cannot be enabled via cmdline. 2698 See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst> 2699 2700endif 2701 2702config ARCH_HAS_ADD_PAGES 2703 def_bool y 2704 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2705 2706menu "Power management and ACPI options" 2707 2708config ARCH_HIBERNATION_HEADER 2709 def_bool y 2710 depends on HIBERNATION 2711 2712source "kernel/power/Kconfig" 2713 2714source "drivers/acpi/Kconfig" 2715 2716config X86_APM_BOOT 2717 def_bool y 2718 depends on APM 2719 2720menuconfig APM 2721 tristate "APM (Advanced Power Management) BIOS support" 2722 depends on X86_32 && PM_SLEEP 2723 help 2724 APM is a BIOS specification for saving power using several different 2725 techniques. This is mostly useful for battery powered laptops with 2726 APM compliant BIOSes. If you say Y here, the system time will be 2727 reset after a RESUME operation, the /proc/apm device will provide 2728 battery status information, and user-space programs will receive 2729 notification of APM "events" (e.g. battery status change). 2730 2731 If you select "Y" here, you can disable actual use of the APM 2732 BIOS by passing the "apm=off" option to the kernel at boot time. 2733 2734 Note that the APM support is almost completely disabled for 2735 machines with more than one CPU. 2736 2737 In order to use APM, you will need supporting software. For location 2738 and more information, read <file:Documentation/power/apm-acpi.rst> 2739 and the Battery Powered Linux mini-HOWTO, available from 2740 <http://www.tldp.org/docs.html#howto>. 2741 2742 This driver does not spin down disk drives (see the hdparm(8) 2743 manpage ("man 8 hdparm") for that), and it doesn't turn off 2744 VESA-compliant "green" monitors. 2745 2746 This driver does not support the TI 4000M TravelMate and the ACER 2747 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2748 desktop machines also don't have compliant BIOSes, and this driver 2749 may cause those machines to panic during the boot phase. 2750 2751 Generally, if you don't have a battery in your machine, there isn't 2752 much point in using this driver and you should say N. If you get 2753 random kernel OOPSes or reboots that don't seem to be related to 2754 anything, try disabling/enabling this option (or disabling/enabling 2755 APM in your BIOS). 2756 2757 Some other things you should try when experiencing seemingly random, 2758 "weird" problems: 2759 2760 1) make sure that you have enough swap space and that it is 2761 enabled. 2762 2) pass the "idle=poll" option to the kernel 2763 3) switch on floating point emulation in the kernel and pass 2764 the "no387" option to the kernel 2765 4) pass the "floppy=nodma" option to the kernel 2766 5) pass the "mem=4M" option to the kernel (thereby disabling 2767 all but the first 4 MB of RAM) 2768 6) make sure that the CPU is not over clocked. 2769 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2770 8) disable the cache from your BIOS settings 2771 9) install a fan for the video card or exchange video RAM 2772 10) install a better fan for the CPU 2773 11) exchange RAM chips 2774 12) exchange the motherboard. 2775 2776 To compile this driver as a module, choose M here: the 2777 module will be called apm. 2778 2779if APM 2780 2781config APM_IGNORE_USER_SUSPEND 2782 bool "Ignore USER SUSPEND" 2783 help 2784 This option will ignore USER SUSPEND requests. On machines with a 2785 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2786 series notebooks, it is necessary to say Y because of a BIOS bug. 2787 2788config APM_DO_ENABLE 2789 bool "Enable PM at boot time" 2790 help 2791 Enable APM features at boot time. From page 36 of the APM BIOS 2792 specification: "When disabled, the APM BIOS does not automatically 2793 power manage devices, enter the Standby State, enter the Suspend 2794 State, or take power saving steps in response to CPU Idle calls." 2795 This driver will make CPU Idle calls when Linux is idle (unless this 2796 feature is turned off -- see "Do CPU IDLE calls", below). This 2797 should always save battery power, but more complicated APM features 2798 will be dependent on your BIOS implementation. You may need to turn 2799 this option off if your computer hangs at boot time when using APM 2800 support, or if it beeps continuously instead of suspending. Turn 2801 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2802 T400CDT. This is off by default since most machines do fine without 2803 this feature. 2804 2805config APM_CPU_IDLE 2806 depends on CPU_IDLE 2807 bool "Make CPU Idle calls when idle" 2808 help 2809 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2810 On some machines, this can activate improved power savings, such as 2811 a slowed CPU clock rate, when the machine is idle. These idle calls 2812 are made after the idle loop has run for some length of time (e.g., 2813 333 mS). On some machines, this will cause a hang at boot time or 2814 whenever the CPU becomes idle. (On machines with more than one CPU, 2815 this option does nothing.) 2816 2817config APM_DISPLAY_BLANK 2818 bool "Enable console blanking using APM" 2819 help 2820 Enable console blanking using the APM. Some laptops can use this to 2821 turn off the LCD backlight when the screen blanker of the Linux 2822 virtual console blanks the screen. Note that this is only used by 2823 the virtual console screen blanker, and won't turn off the backlight 2824 when using the X Window system. This also doesn't have anything to 2825 do with your VESA-compliant power-saving monitor. Further, this 2826 option doesn't work for all laptops -- it might not turn off your 2827 backlight at all, or it might print a lot of errors to the console, 2828 especially if you are using gpm. 2829 2830config APM_ALLOW_INTS 2831 bool "Allow interrupts during APM BIOS calls" 2832 help 2833 Normally we disable external interrupts while we are making calls to 2834 the APM BIOS as a measure to lessen the effects of a badly behaving 2835 BIOS implementation. The BIOS should reenable interrupts if it 2836 needs to. Unfortunately, some BIOSes do not -- especially those in 2837 many of the newer IBM Thinkpads. If you experience hangs when you 2838 suspend, try setting this to Y. Otherwise, say N. 2839 2840endif # APM 2841 2842source "drivers/cpufreq/Kconfig" 2843 2844source "drivers/cpuidle/Kconfig" 2845 2846source "drivers/idle/Kconfig" 2847 2848endmenu 2849 2850menu "Bus options (PCI etc.)" 2851 2852choice 2853 prompt "PCI access mode" 2854 depends on X86_32 && PCI 2855 default PCI_GOANY 2856 help 2857 On PCI systems, the BIOS can be used to detect the PCI devices and 2858 determine their configuration. However, some old PCI motherboards 2859 have BIOS bugs and may crash if this is done. Also, some embedded 2860 PCI-based systems don't have any BIOS at all. Linux can also try to 2861 detect the PCI hardware directly without using the BIOS. 2862 2863 With this option, you can specify how Linux should detect the 2864 PCI devices. If you choose "BIOS", the BIOS will be used, 2865 if you choose "Direct", the BIOS won't be used, and if you 2866 choose "MMConfig", then PCI Express MMCONFIG will be used. 2867 If you choose "Any", the kernel will try MMCONFIG, then the 2868 direct access method and falls back to the BIOS if that doesn't 2869 work. If unsure, go with the default, which is "Any". 2870 2871config PCI_GOBIOS 2872 bool "BIOS" 2873 2874config PCI_GOMMCONFIG 2875 bool "MMConfig" 2876 2877config PCI_GODIRECT 2878 bool "Direct" 2879 2880config PCI_GOOLPC 2881 bool "OLPC XO-1" 2882 depends on OLPC 2883 2884config PCI_GOANY 2885 bool "Any" 2886 2887endchoice 2888 2889config PCI_BIOS 2890 def_bool y 2891 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2892 2893# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2894config PCI_DIRECT 2895 def_bool y 2896 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2897 2898config PCI_MMCONFIG 2899 bool "Support mmconfig PCI config space access" if X86_64 2900 default y 2901 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2902 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2903 help 2904 Add support for accessing the PCI configuration space as a memory 2905 mapped area. It is the recommended method if the system supports 2906 this (it must have PCI Express and ACPI for it to be available). 2907 2908 In the unlikely case that enabling this configuration option causes 2909 problems, the mechanism can be switched off with the 'pci=nommconf' 2910 command line parameter. 2911 2912 Say N only if you are sure that your platform does not support this 2913 access method or you have problems caused by it. 2914 2915 Say Y otherwise. 2916 2917config PCI_OLPC 2918 def_bool y 2919 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2920 2921config PCI_XEN 2922 def_bool y 2923 depends on PCI && XEN 2924 2925config MMCONF_FAM10H 2926 def_bool y 2927 depends on X86_64 && PCI_MMCONFIG && ACPI 2928 2929config PCI_CNB20LE_QUIRK 2930 bool "Read PCI host bridge windows from the CNB20LE chipset" if EXPERT 2931 depends on X86_32 && PCI 2932 help 2933 Read the PCI windows out of the CNB20LE host bridge. This allows 2934 PCI hotplug to work on systems with the CNB20LE chipset which do 2935 not have ACPI. 2936 2937 The ServerWorks (later Broadcom) CNB20LE was a chipset designed 2938 most probably only for Pentium III. 2939 2940 To find out if you have such a chipset, search for a PCI device with 2941 1166:0009 PCI IDs, for example by executing 2942 lspci -nn | grep '1166:0009' 2943 The code is inactive if there is none. 2944 2945 There's no public spec for this chipset, and this functionality 2946 is known to be incomplete. 2947 2948 You should say N unless you know you need this. 2949 2950config ISA_BUS 2951 bool "ISA bus support on modern systems" if EXPERT 2952 help 2953 Expose ISA bus device drivers and options available for selection and 2954 configuration. Enable this option if your target machine has an ISA 2955 bus. ISA is an older system, displaced by PCI and newer bus 2956 architectures -- if your target machine is modern, it probably does 2957 not have an ISA bus. 2958 2959 If unsure, say N. 2960 2961# x86_64 have no ISA slots, but can have ISA-style DMA. 2962config ISA_DMA_API 2963 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2964 default y 2965 help 2966 Enables ISA-style DMA support for devices requiring such controllers. 2967 If unsure, say Y. 2968 2969if X86_32 2970 2971config ISA 2972 bool "ISA support" 2973 help 2974 Find out whether you have ISA slots on your motherboard. ISA is the 2975 name of a bus system, i.e. the way the CPU talks to the other stuff 2976 inside your box. Other bus systems are PCI, EISA, MicroChannel 2977 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2978 newer boards don't support it. If you have ISA, say Y, otherwise N. 2979 2980config SCx200 2981 tristate "NatSemi SCx200 support" 2982 help 2983 This provides basic support for National Semiconductor's 2984 (now AMD's) Geode processors. The driver probes for the 2985 PCI-IDs of several on-chip devices, so its a good dependency 2986 for other scx200_* drivers. 2987 2988 If compiled as a module, the driver is named scx200. 2989 2990config SCx200HR_TIMER 2991 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2992 depends on SCx200 2993 default y 2994 help 2995 This driver provides a clocksource built upon the on-chip 2996 27MHz high-resolution timer. Its also a workaround for 2997 NSC Geode SC-1100's buggy TSC, which loses time when the 2998 processor goes idle (as is done by the scheduler). The 2999 other workaround is idle=poll boot option. 3000 3001config OLPC 3002 bool "One Laptop Per Child support" 3003 depends on !X86_PAE 3004 select GPIOLIB 3005 select OF 3006 select OF_PROMTREE 3007 select IRQ_DOMAIN 3008 select OLPC_EC 3009 help 3010 Add support for detecting the unique features of the OLPC 3011 XO hardware. 3012 3013config OLPC_XO1_PM 3014 bool "OLPC XO-1 Power Management" 3015 depends on OLPC && MFD_CS5535=y && PM_SLEEP 3016 help 3017 Add support for poweroff and suspend of the OLPC XO-1 laptop. 3018 3019config OLPC_XO1_RTC 3020 bool "OLPC XO-1 Real Time Clock" 3021 depends on OLPC_XO1_PM && RTC_DRV_CMOS 3022 help 3023 Add support for the XO-1 real time clock, which can be used as a 3024 programmable wakeup source. 3025 3026config OLPC_XO1_SCI 3027 bool "OLPC XO-1 SCI extras" 3028 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 3029 depends on INPUT=y 3030 select POWER_SUPPLY 3031 help 3032 Add support for SCI-based features of the OLPC XO-1 laptop: 3033 - EC-driven system wakeups 3034 - Power button 3035 - Ebook switch 3036 - Lid switch 3037 - AC adapter status updates 3038 - Battery status updates 3039 3040config OLPC_XO15_SCI 3041 bool "OLPC XO-1.5 SCI extras" 3042 depends on OLPC && ACPI 3043 select POWER_SUPPLY 3044 help 3045 Add support for SCI-based features of the OLPC XO-1.5 laptop: 3046 - EC-driven system wakeups 3047 - AC adapter status updates 3048 - Battery status updates 3049 3050config GEODE_COMMON 3051 bool 3052 3053config ALIX 3054 bool "PCEngines ALIX System Support (LED setup)" 3055 select GPIOLIB 3056 select GEODE_COMMON 3057 help 3058 This option enables system support for the PCEngines ALIX. 3059 At present this just sets up LEDs for GPIO control on 3060 ALIX2/3/6 boards. However, other system specific setup should 3061 get added here. 3062 3063 Note: You must still enable the drivers for GPIO and LED support 3064 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 3065 3066 Note: You have to set alix.force=1 for boards with Award BIOS. 3067 3068config NET5501 3069 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3070 select GPIOLIB 3071 select GEODE_COMMON 3072 help 3073 This option enables system support for the Soekris Engineering net5501. 3074 3075config GEOS 3076 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3077 select GPIOLIB 3078 select GEODE_COMMON 3079 depends on DMI 3080 help 3081 This option enables system support for the Traverse Technologies GEOS. 3082 3083config TS5500 3084 bool "Technologic Systems TS-5500 platform support" 3085 depends on MELAN 3086 select CHECK_SIGNATURE 3087 select NEW_LEDS 3088 select LEDS_CLASS 3089 help 3090 This option enables system support for the Technologic Systems TS-5500. 3091 3092endif # X86_32 3093 3094config AMD_NB 3095 def_bool y 3096 depends on AMD_NODE 3097 3098config AMD_NODE 3099 def_bool y 3100 depends on CPU_SUP_AMD && PCI 3101 3102endmenu 3103 3104menu "Binary Emulations" 3105 3106config IA32_EMULATION 3107 bool "IA32 Emulation" 3108 depends on X86_64 3109 select ARCH_WANT_OLD_COMPAT_IPC 3110 select BINFMT_ELF 3111 select COMPAT_OLD_SIGACTION 3112 help 3113 Include code to run legacy 32-bit programs under a 3114 64-bit kernel. You should likely turn this on, unless you're 3115 100% sure that you don't have any 32-bit programs left. 3116 3117config IA32_EMULATION_DEFAULT_DISABLED 3118 bool "IA32 emulation disabled by default" 3119 default n 3120 depends on IA32_EMULATION 3121 help 3122 Make IA32 emulation disabled by default. This prevents loading 32-bit 3123 processes and access to 32-bit syscalls. If unsure, leave it to its 3124 default value. 3125 3126config X86_X32_ABI 3127 bool "x32 ABI for 64-bit mode" 3128 depends on X86_64 3129 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3130 # compressed debug sections to x86_x32 properly: 3131 # https://github.com/ClangBuiltLinux/linux/issues/514 3132 # https://github.com/ClangBuiltLinux/linux/issues/1141 3133 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3134 help 3135 Include code to run binaries for the x32 native 32-bit ABI 3136 for 64-bit processors. An x32 process gets access to the 3137 full 64-bit register file and wide data path while leaving 3138 pointers at 32 bits for smaller memory footprint. 3139 3140config COMPAT_32 3141 def_bool y 3142 depends on IA32_EMULATION || X86_32 3143 select HAVE_UID16 3144 select OLD_SIGSUSPEND3 3145 3146config COMPAT 3147 def_bool y 3148 depends on IA32_EMULATION || X86_X32_ABI 3149 3150config COMPAT_FOR_U64_ALIGNMENT 3151 def_bool y 3152 depends on COMPAT 3153 3154endmenu 3155 3156config HAVE_ATOMIC_IOMAP 3157 def_bool y 3158 depends on X86_32 3159 3160source "arch/x86/kvm/Kconfig" 3161 3162source "arch/x86/Kconfig.cpufeatures" 3163 3164source "arch/x86/Kconfig.assembler" 3165