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 select ACPI_MRRM if ACPI 42 43config FORCE_DYNAMIC_FTRACE 44 def_bool y 45 depends on X86_32 46 depends on FUNCTION_TRACER 47 select DYNAMIC_FTRACE 48 help 49 We keep the static function tracing (!DYNAMIC_FTRACE) around 50 in order to test the non static function tracing in the 51 generic code, as other architectures still use it. But we 52 only need to keep it around for x86_64. No need to keep it 53 for x86_32. For x86_32, force DYNAMIC_FTRACE. 54# 55# Arch settings 56# 57# ( Note that options that are marked 'if X86_64' could in principle be 58# ported to 32-bit as well. ) 59# 60config X86 61 def_bool y 62 # 63 # Note: keep this list sorted alphabetically 64 # 65 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 66 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 67 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 68 select ARCH_32BIT_OFF_T if X86_32 69 select ARCH_CLOCKSOURCE_INIT 70 select ARCH_CONFIGURES_CPU_MITIGATIONS 71 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 72 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 73 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 74 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 75 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 76 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 77 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 78 select ARCH_HAS_CACHE_LINE_SIZE 79 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 80 select ARCH_HAS_CPU_FINALIZE_INIT 81 select ARCH_HAS_CPU_PASID if IOMMU_SVA 82 select ARCH_HAS_CRC32 83 select ARCH_HAS_CRC64 if X86_64 84 select ARCH_HAS_CRC_T10DIF 85 select ARCH_HAS_CURRENT_STACK_POINTER 86 select ARCH_HAS_DEBUG_VIRTUAL 87 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 88 select ARCH_HAS_DEVMEM_IS_ALLOWED 89 select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN 90 select ARCH_HAS_EARLY_DEBUG if KGDB 91 select ARCH_HAS_ELF_RANDOMIZE 92 select ARCH_HAS_EXECMEM_ROX if X86_64 && STRICT_MODULE_RWX 93 select ARCH_HAS_FAST_MULTIPLIER 94 select ARCH_HAS_FORTIFY_SOURCE 95 select ARCH_HAS_GCOV_PROFILE_ALL 96 select ARCH_HAS_KCOV if X86_64 97 select ARCH_HAS_KERNEL_FPU_SUPPORT 98 select ARCH_HAS_MEM_ENCRYPT 99 select ARCH_HAS_MEMBARRIER_SYNC_CORE 100 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 101 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 102 select ARCH_HAS_PMEM_API if X86_64 103 select ARCH_HAS_PREEMPT_LAZY 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 depends on MISC_FILESYSTEMS 511 select ARCH_HAS_CPU_RESCTRL 512 select RESCTRL_FS 513 select RESCTRL_FS_PSEUDO_LOCK 514 help 515 Enable x86 CPU resource control support. 516 517 Provide support for the allocation and monitoring of system resources 518 usage by the CPU. 519 520 Intel calls this Intel Resource Director Technology 521 (Intel(R) RDT). More information about RDT can be found in the 522 Intel x86 Architecture Software Developer Manual. 523 524 AMD calls this AMD Platform Quality of Service (AMD QoS). 525 More information about AMD QoS can be found in the AMD64 Technology 526 Platform Quality of Service Extensions manual. 527 528 Say N if unsure. 529 530config X86_FRED 531 bool "Flexible Return and Event Delivery" 532 depends on X86_64 533 help 534 When enabled, try to use Flexible Return and Event Delivery 535 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 536 ring transitions and exception/interrupt handling if the 537 system supports it. 538 539config X86_EXTENDED_PLATFORM 540 bool "Support for extended (non-PC) x86 platforms" 541 default y 542 help 543 If you disable this option then the kernel will only support 544 standard PC platforms. (which covers the vast majority of 545 systems out there.) 546 547 If you enable this option then you'll be able to select support 548 for the following non-PC x86 platforms, depending on the value of 549 CONFIG_64BIT. 550 551 32-bit platforms (CONFIG_64BIT=n): 552 Goldfish (mostly Android emulator) 553 Intel CE media processor (CE4100) SoC 554 Intel Quark 555 RDC R-321x SoC 556 557 64-bit platforms (CONFIG_64BIT=y): 558 Numascale NumaChip 559 ScaleMP vSMP 560 SGI Ultraviolet 561 Merrifield/Moorefield MID devices 562 Goldfish (mostly Android emulator) 563 564 If you have one of these systems, or if you want to build a 565 generic distribution kernel, say Y here - otherwise say N. 566 567# This is an alphabetically sorted list of 64 bit extended platforms 568# Please maintain the alphabetic order if and when there are additions 569config X86_NUMACHIP 570 bool "Numascale NumaChip" 571 depends on X86_64 572 depends on X86_EXTENDED_PLATFORM 573 depends on NUMA 574 depends on SMP 575 depends on X86_X2APIC 576 depends on PCI_MMCONFIG 577 help 578 Adds support for Numascale NumaChip large-SMP systems. Needed to 579 enable more than ~168 cores. 580 If you don't have one of these, you should say N here. 581 582config X86_VSMP 583 bool "ScaleMP vSMP" 584 select HYPERVISOR_GUEST 585 select PARAVIRT 586 depends on X86_64 && PCI 587 depends on X86_EXTENDED_PLATFORM 588 depends on SMP 589 help 590 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 591 supposed to run on these EM64T-based machines. Only choose this option 592 if you have one of these machines. 593 594config X86_UV 595 bool "SGI Ultraviolet" 596 depends on X86_64 597 depends on X86_EXTENDED_PLATFORM 598 depends on NUMA 599 depends on EFI 600 depends on KEXEC_CORE 601 depends on X86_X2APIC 602 depends on PCI 603 help 604 This option is needed in order to support SGI Ultraviolet systems. 605 If you don't have one of these, you should say N here. 606 607config X86_INTEL_MID 608 bool "Intel Z34xx/Z35xx MID platform support" 609 depends on X86_EXTENDED_PLATFORM 610 depends on X86_PLATFORM_DEVICES 611 depends on PCI 612 depends on X86_64 || (EXPERT && PCI_GOANY) 613 depends on X86_IO_APIC 614 select I2C 615 select DW_APB_TIMER 616 select INTEL_SCU_PCI 617 help 618 Select to build a kernel capable of supporting 64-bit Intel MID 619 (Mobile Internet Device) platform systems which do not have 620 the PCI legacy interfaces. 621 622 The only supported devices are the 22nm Merrified (Z34xx) 623 and Moorefield (Z35xx) SoC used in the Intel Edison board and 624 a small number of Android devices such as the Asus Zenfone 2, 625 Asus FonePad 8 and Dell Venue 7. 626 627 If you are building for a PC class system or non-MID tablet 628 SoCs like Bay Trail (Z36xx/Z37xx), say N here. 629 630 Intel MID platforms are based on an Intel processor and chipset which 631 consume less power than most of the x86 derivatives. 632 633config X86_GOLDFISH 634 bool "Goldfish (Virtual Platform)" 635 depends on X86_EXTENDED_PLATFORM 636 help 637 Enable support for the Goldfish virtual platform used primarily 638 for Android development. Unless you are building for the Android 639 Goldfish emulator say N here. 640 641# Following is an alphabetically sorted list of 32 bit extended platforms 642# Please maintain the alphabetic order if and when there are additions 643 644config X86_INTEL_CE 645 bool "CE4100 TV platform" 646 depends on PCI 647 depends on PCI_GODIRECT 648 depends on X86_IO_APIC 649 depends on X86_32 650 depends on X86_EXTENDED_PLATFORM 651 select X86_REBOOTFIXUPS 652 select OF 653 select OF_EARLY_FLATTREE 654 help 655 Select for the Intel CE media processor (CE4100) SOC. 656 This option compiles in support for the CE4100 SOC for settop 657 boxes and media devices. 658 659config X86_INTEL_QUARK 660 bool "Intel Quark platform support" 661 depends on X86_32 662 depends on X86_EXTENDED_PLATFORM 663 depends on X86_PLATFORM_DEVICES 664 depends on X86_TSC 665 depends on PCI 666 depends on PCI_GOANY 667 depends on X86_IO_APIC 668 select IOSF_MBI 669 select INTEL_IMR 670 select COMMON_CLK 671 help 672 Select to include support for Quark X1000 SoC. 673 Say Y here if you have a Quark based system such as the Arduino 674 compatible Intel Galileo. 675 676config X86_RDC321X 677 bool "RDC R-321x SoC" 678 depends on X86_32 679 depends on X86_EXTENDED_PLATFORM 680 select M486 681 select X86_REBOOTFIXUPS 682 help 683 This option is needed for RDC R-321x system-on-chip, also known 684 as R-8610-(G). 685 If you don't have one of these chips, you should say N here. 686 687config X86_INTEL_LPSS 688 bool "Intel Low Power Subsystem Support" 689 depends on X86 && ACPI && PCI 690 select COMMON_CLK 691 select PINCTRL 692 select IOSF_MBI 693 help 694 Select to build support for Intel Low Power Subsystem such as 695 found on Intel Lynxpoint PCH. Selecting this option enables 696 things like clock tree (common clock framework) and pincontrol 697 which are needed by the LPSS peripheral drivers. 698 699config X86_AMD_PLATFORM_DEVICE 700 bool "AMD ACPI2Platform devices support" 701 depends on ACPI 702 select COMMON_CLK 703 select PINCTRL 704 help 705 Select to interpret AMD specific ACPI device to platform device 706 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 707 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 708 implemented under PINCTRL subsystem. 709 710config IOSF_MBI 711 tristate "Intel SoC IOSF Sideband support for SoC platforms" 712 depends on PCI 713 help 714 This option enables sideband register access support for Intel SoC 715 platforms. On these platforms the IOSF sideband is used in lieu of 716 MSR's for some register accesses, mostly but not limited to thermal 717 and power. Drivers may query the availability of this device to 718 determine if they need the sideband in order to work on these 719 platforms. The sideband is available on the following SoC products. 720 This list is not meant to be exclusive. 721 - BayTrail 722 - Braswell 723 - Quark 724 725 You should say Y if you are running a kernel on one of these SoC's. 726 727config IOSF_MBI_DEBUG 728 bool "Enable IOSF sideband access through debugfs" 729 depends on IOSF_MBI && DEBUG_FS 730 help 731 Select this option to expose the IOSF sideband access registers (MCR, 732 MDR, MCRX) through debugfs to write and read register information from 733 different units on the SoC. This is most useful for obtaining device 734 state information for debug and analysis. As this is a general access 735 mechanism, users of this option would have specific knowledge of the 736 device they want to access. 737 738 If you don't require the option or are in doubt, say N. 739 740config X86_SUPPORTS_MEMORY_FAILURE 741 def_bool y 742 # MCE code calls memory_failure(): 743 depends on X86_MCE 744 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 745 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 746 depends on X86_64 || !SPARSEMEM 747 select ARCH_SUPPORTS_MEMORY_FAILURE 748 749config X86_32_IRIS 750 tristate "Eurobraille/Iris poweroff module" 751 depends on X86_32 752 help 753 The Iris machines from EuroBraille do not have APM or ACPI support 754 to shut themselves down properly. A special I/O sequence is 755 needed to do so, which is what this module does at 756 kernel shutdown. 757 758 This is only for Iris machines from EuroBraille. 759 760 If unused, say N. 761 762config SCHED_OMIT_FRAME_POINTER 763 def_bool y 764 prompt "Single-depth WCHAN output" 765 depends on X86 766 help 767 Calculate simpler /proc/<PID>/wchan values. If this option 768 is disabled then wchan values will recurse back to the 769 caller function. This provides more accurate wchan values, 770 at the expense of slightly more scheduling overhead. 771 772 If in doubt, say "Y". 773 774menuconfig HYPERVISOR_GUEST 775 bool "Linux guest support" 776 help 777 Say Y here to enable options for running Linux under various hyper- 778 visors. This option enables basic hypervisor detection and platform 779 setup. 780 781 If you say N, all options in this submenu will be skipped and 782 disabled, and Linux guest support won't be built in. 783 784if HYPERVISOR_GUEST 785 786config PARAVIRT 787 bool "Enable paravirtualization code" 788 depends on HAVE_STATIC_CALL 789 help 790 This changes the kernel so it can modify itself when it is run 791 under a hypervisor, potentially improving performance significantly 792 over full virtualization. However, when run without a hypervisor 793 the kernel is theoretically slower and slightly larger. 794 795config PARAVIRT_XXL 796 bool 797 depends on X86_64 798 799config PARAVIRT_DEBUG 800 bool "paravirt-ops debugging" 801 depends on PARAVIRT && DEBUG_KERNEL 802 help 803 Enable to debug paravirt_ops internals. Specifically, BUG if 804 a paravirt_op is missing when it is called. 805 806config PARAVIRT_SPINLOCKS 807 bool "Paravirtualization layer for spinlocks" 808 depends on PARAVIRT && SMP 809 help 810 Paravirtualized spinlocks allow a pvops backend to replace the 811 spinlock implementation with something virtualization-friendly 812 (for example, block the virtual CPU rather than spinning). 813 814 It has a minimal impact on native kernels and gives a nice performance 815 benefit on paravirtualized KVM / Xen kernels. 816 817 If you are unsure how to answer this question, answer Y. 818 819config X86_HV_CALLBACK_VECTOR 820 def_bool n 821 822source "arch/x86/xen/Kconfig" 823 824config KVM_GUEST 825 bool "KVM Guest support (including kvmclock)" 826 depends on PARAVIRT 827 select PARAVIRT_CLOCK 828 select ARCH_CPUIDLE_HALTPOLL 829 select X86_HV_CALLBACK_VECTOR 830 default y 831 help 832 This option enables various optimizations for running under the KVM 833 hypervisor. It includes a paravirtualized clock, so that instead 834 of relying on a PIT (or probably other) emulation by the 835 underlying device model, the host provides the guest with 836 timing infrastructure such as time of day, and system time 837 838config ARCH_CPUIDLE_HALTPOLL 839 def_bool n 840 prompt "Disable host haltpoll when loading haltpoll driver" 841 help 842 If virtualized under KVM, disable host haltpoll. 843 844config PVH 845 bool "Support for running PVH guests" 846 help 847 This option enables the PVH entry point for guest virtual machines 848 as specified in the x86/HVM direct boot ABI. 849 850config PARAVIRT_TIME_ACCOUNTING 851 bool "Paravirtual steal time accounting" 852 depends on PARAVIRT 853 help 854 Select this option to enable fine granularity task steal time 855 accounting. Time spent executing other tasks in parallel with 856 the current vCPU is discounted from the vCPU power. To account for 857 that, there can be a small performance impact. 858 859 If in doubt, say N here. 860 861config PARAVIRT_CLOCK 862 bool 863 864config JAILHOUSE_GUEST 865 bool "Jailhouse non-root cell support" 866 depends on X86_64 && PCI 867 select X86_PM_TIMER 868 help 869 This option allows to run Linux as guest in a Jailhouse non-root 870 cell. You can leave this option disabled if you only want to start 871 Jailhouse and run Linux afterwards in the root cell. 872 873config ACRN_GUEST 874 bool "ACRN Guest support" 875 depends on X86_64 876 select X86_HV_CALLBACK_VECTOR 877 help 878 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 879 a flexible, lightweight reference open-source hypervisor, built with 880 real-time and safety-criticality in mind. It is built for embedded 881 IOT with small footprint and real-time features. More details can be 882 found in https://projectacrn.org/. 883 884config INTEL_TDX_GUEST 885 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 886 depends on X86_64 && CPU_SUP_INTEL 887 depends on X86_X2APIC 888 depends on EFI_STUB 889 depends on PARAVIRT 890 select ARCH_HAS_CC_PLATFORM 891 select X86_MEM_ENCRYPT 892 select X86_MCE 893 select UNACCEPTED_MEMORY 894 help 895 Support running as a guest under Intel TDX. Without this support, 896 the guest kernel can not boot or run under TDX. 897 TDX includes memory encryption and integrity capabilities 898 which protect the confidentiality and integrity of guest 899 memory contents and CPU state. TDX guests are protected from 900 some attacks from the VMM. 901 902endif # HYPERVISOR_GUEST 903 904source "arch/x86/Kconfig.cpu" 905 906config HPET_TIMER 907 def_bool X86_64 908 prompt "HPET Timer Support" if X86_32 909 help 910 Use the IA-PC HPET (High Precision Event Timer) to manage 911 time in preference to the PIT and RTC, if a HPET is 912 present. 913 HPET is the next generation timer replacing legacy 8254s. 914 The HPET provides a stable time base on SMP 915 systems, unlike the TSC, but it is more expensive to access, 916 as it is off-chip. The interface used is documented 917 in the HPET spec, revision 1. 918 919 You can safely choose Y here. However, HPET will only be 920 activated if the platform and the BIOS support this feature. 921 Otherwise the 8254 will be used for timing services. 922 923 Choose N to continue using the legacy 8254 timer. 924 925config HPET_EMULATE_RTC 926 def_bool y 927 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 928 929# Mark as expert because too many people got it wrong. 930# The code disables itself when not needed. 931config DMI 932 default y 933 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 934 bool "Enable DMI scanning" if EXPERT 935 help 936 Enabled scanning of DMI to identify machine quirks. Say Y 937 here unless you have verified that your setup is not 938 affected by entries in the DMI blacklist. Required by PNP 939 BIOS code. 940 941config GART_IOMMU 942 bool "Old AMD GART IOMMU support" 943 select IOMMU_HELPER 944 select SWIOTLB 945 depends on X86_64 && PCI && AMD_NB 946 help 947 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 948 GART based hardware IOMMUs. 949 950 The GART supports full DMA access for devices with 32-bit access 951 limitations, on systems with more than 3 GB. This is usually needed 952 for USB, sound, many IDE/SATA chipsets and some other devices. 953 954 Newer systems typically have a modern AMD IOMMU, supported via 955 the CONFIG_AMD_IOMMU=y config option. 956 957 In normal configurations this driver is only active when needed: 958 there's more than 3 GB of memory and the system contains a 959 32-bit limited device. 960 961 If unsure, say Y. 962 963config BOOT_VESA_SUPPORT 964 bool 965 help 966 If true, at least one selected framebuffer driver can take advantage 967 of VESA video modes set at an early boot stage via the vga= parameter. 968 969config MAXSMP 970 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 971 depends on X86_64 && SMP && DEBUG_KERNEL 972 select CPUMASK_OFFSTACK 973 help 974 Enable maximum number of CPUS and NUMA Nodes for this architecture. 975 If unsure, say N. 976 977# 978# The maximum number of CPUs supported: 979# 980# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 981# and which can be configured interactively in the 982# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 983# 984# The ranges are different on 32-bit and 64-bit kernels, depending on 985# hardware capabilities and scalability features of the kernel. 986# 987# ( If MAXSMP is enabled we just use the highest possible value and disable 988# interactive configuration. ) 989# 990 991config NR_CPUS_RANGE_BEGIN 992 int 993 default NR_CPUS_RANGE_END if MAXSMP 994 default 1 if !SMP 995 default 2 996 997config NR_CPUS_RANGE_END 998 int 999 depends on X86_32 1000 default 8 if SMP 1001 default 1 if !SMP 1002 1003config NR_CPUS_RANGE_END 1004 int 1005 depends on X86_64 1006 default 8192 if SMP && CPUMASK_OFFSTACK 1007 default 512 if SMP && !CPUMASK_OFFSTACK 1008 default 1 if !SMP 1009 1010config NR_CPUS_DEFAULT 1011 int 1012 depends on X86_32 1013 default 8 if SMP 1014 default 1 if !SMP 1015 1016config NR_CPUS_DEFAULT 1017 int 1018 depends on X86_64 1019 default 8192 if MAXSMP 1020 default 64 if SMP 1021 default 1 if !SMP 1022 1023config NR_CPUS 1024 int "Maximum number of CPUs" if SMP && !MAXSMP 1025 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1026 default NR_CPUS_DEFAULT 1027 help 1028 This allows you to specify the maximum number of CPUs which this 1029 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1030 supported value is 8192, otherwise the maximum value is 512. The 1031 minimum value which makes sense is 2. 1032 1033 This is purely to save memory: each supported CPU adds about 8KB 1034 to the kernel image. 1035 1036config SCHED_CLUSTER 1037 bool "Cluster scheduler support" 1038 depends on SMP 1039 default y 1040 help 1041 Cluster scheduler support improves the CPU scheduler's decision 1042 making when dealing with machines that have clusters of CPUs. 1043 Cluster usually means a couple of CPUs which are placed closely 1044 by sharing mid-level caches, last-level cache tags or internal 1045 busses. 1046 1047config SCHED_SMT 1048 def_bool y if SMP 1049 1050config SCHED_MC 1051 def_bool y 1052 prompt "Multi-core scheduler support" 1053 depends on SMP 1054 help 1055 Multi-core scheduler support improves the CPU scheduler's decision 1056 making when dealing with multi-core CPU chips at a cost of slightly 1057 increased overhead in some places. If unsure say N here. 1058 1059config SCHED_MC_PRIO 1060 bool "CPU core priorities scheduler support" 1061 depends on SCHED_MC 1062 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1063 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1064 select CPU_FREQ 1065 default y 1066 help 1067 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1068 core ordering determined at manufacturing time, which allows 1069 certain cores to reach higher turbo frequencies (when running 1070 single threaded workloads) than others. 1071 1072 Enabling this kernel feature teaches the scheduler about 1073 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1074 scheduler's CPU selection logic accordingly, so that higher 1075 overall system performance can be achieved. 1076 1077 This feature will have no effect on CPUs without this feature. 1078 1079 If unsure say Y here. 1080 1081config UP_LATE_INIT 1082 def_bool y 1083 depends on !SMP && X86_LOCAL_APIC 1084 1085config X86_UP_APIC 1086 bool "Local APIC support on uniprocessors" if !PCI_MSI 1087 default PCI_MSI 1088 depends on X86_32 && !SMP 1089 help 1090 A local APIC (Advanced Programmable Interrupt Controller) is an 1091 integrated interrupt controller in the CPU. If you have a single-CPU 1092 system which has a processor with a local APIC, you can say Y here to 1093 enable and use it. If you say Y here even though your machine doesn't 1094 have a local APIC, then the kernel will still run with no slowdown at 1095 all. The local APIC supports CPU-generated self-interrupts (timer, 1096 performance counters), and the NMI watchdog which detects hard 1097 lockups. 1098 1099config X86_UP_IOAPIC 1100 bool "IO-APIC support on uniprocessors" 1101 depends on X86_UP_APIC 1102 help 1103 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1104 SMP-capable replacement for PC-style interrupt controllers. Most 1105 SMP systems and many recent uniprocessor systems have one. 1106 1107 If you have a single-CPU system with an IO-APIC, you can say Y here 1108 to use it. If you say Y here even though your machine doesn't have 1109 an IO-APIC, then the kernel will still run with no slowdown at all. 1110 1111config X86_LOCAL_APIC 1112 def_bool y 1113 depends on X86_64 || SMP || X86_UP_APIC || PCI_MSI 1114 select IRQ_DOMAIN_HIERARCHY 1115 1116config ACPI_MADT_WAKEUP 1117 def_bool y 1118 depends on X86_64 1119 depends on ACPI 1120 depends on SMP 1121 depends on X86_LOCAL_APIC 1122 1123config X86_IO_APIC 1124 def_bool y 1125 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1126 1127config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1128 bool "Reroute for broken boot IRQs" 1129 depends on X86_IO_APIC 1130 help 1131 This option enables a workaround that fixes a source of 1132 spurious interrupts. This is recommended when threaded 1133 interrupt handling is used on systems where the generation of 1134 superfluous "boot interrupts" cannot be disabled. 1135 1136 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1137 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1138 kernel does during interrupt handling). On chipsets where this 1139 boot IRQ generation cannot be disabled, this workaround keeps 1140 the original IRQ line masked so that only the equivalent "boot 1141 IRQ" is delivered to the CPUs. The workaround also tells the 1142 kernel to set up the IRQ handler on the boot IRQ line. In this 1143 way only one interrupt is delivered to the kernel. Otherwise 1144 the spurious second interrupt may cause the kernel to bring 1145 down (vital) interrupt lines. 1146 1147 Only affects "broken" chipsets. Interrupt sharing may be 1148 increased on these systems. 1149 1150config X86_MCE 1151 bool "Machine Check / overheating reporting" 1152 select GENERIC_ALLOCATOR 1153 default y 1154 help 1155 Machine Check support allows the processor to notify the 1156 kernel if it detects a problem (e.g. overheating, data corruption). 1157 The action the kernel takes depends on the severity of the problem, 1158 ranging from warning messages to halting the machine. 1159 1160config X86_MCELOG_LEGACY 1161 bool "Support for deprecated /dev/mcelog character device" 1162 depends on X86_MCE 1163 help 1164 Enable support for /dev/mcelog which is needed by the old mcelog 1165 userspace logging daemon. Consider switching to the new generation 1166 rasdaemon solution. 1167 1168config X86_MCE_INTEL 1169 def_bool y 1170 prompt "Intel MCE features" 1171 depends on X86_MCE && X86_LOCAL_APIC 1172 help 1173 Additional support for intel specific MCE features such as 1174 the thermal monitor. 1175 1176config X86_MCE_AMD 1177 def_bool y 1178 prompt "AMD MCE features" 1179 depends on X86_MCE && X86_LOCAL_APIC 1180 help 1181 Additional support for AMD specific MCE features such as 1182 the DRAM Error Threshold. 1183 1184config X86_ANCIENT_MCE 1185 bool "Support for old Pentium 5 / WinChip machine checks" 1186 depends on X86_32 && X86_MCE 1187 help 1188 Include support for machine check handling on old Pentium 5 or WinChip 1189 systems. These typically need to be enabled explicitly on the command 1190 line. 1191 1192config X86_MCE_THRESHOLD 1193 depends on X86_MCE_AMD || X86_MCE_INTEL 1194 def_bool y 1195 1196config X86_MCE_INJECT 1197 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1198 tristate "Machine check injector support" 1199 help 1200 Provide support for injecting machine checks for testing purposes. 1201 If you don't know what a machine check is and you don't do kernel 1202 QA it is safe to say n. 1203 1204source "arch/x86/events/Kconfig" 1205 1206config X86_LEGACY_VM86 1207 bool "Legacy VM86 support" 1208 depends on X86_32 1209 help 1210 This option allows user programs to put the CPU into V8086 1211 mode, which is an 80286-era approximation of 16-bit real mode. 1212 1213 Some very old versions of X and/or vbetool require this option 1214 for user mode setting. Similarly, DOSEMU will use it if 1215 available to accelerate real mode DOS programs. However, any 1216 recent version of DOSEMU, X, or vbetool should be fully 1217 functional even without kernel VM86 support, as they will all 1218 fall back to software emulation. Nevertheless, if you are using 1219 a 16-bit DOS program where 16-bit performance matters, vm86 1220 mode might be faster than emulation and you might want to 1221 enable this option. 1222 1223 Note that any app that works on a 64-bit kernel is unlikely to 1224 need this option, as 64-bit kernels don't, and can't, support 1225 V8086 mode. This option is also unrelated to 16-bit protected 1226 mode and is not needed to run most 16-bit programs under Wine. 1227 1228 Enabling this option increases the complexity of the kernel 1229 and slows down exception handling a tiny bit. 1230 1231 If unsure, say N here. 1232 1233config VM86 1234 bool 1235 default X86_LEGACY_VM86 1236 1237config X86_16BIT 1238 bool "Enable support for 16-bit segments" if EXPERT 1239 default y 1240 depends on MODIFY_LDT_SYSCALL 1241 help 1242 This option is required by programs like Wine to run 16-bit 1243 protected mode legacy code on x86 processors. Disabling 1244 this option saves about 300 bytes on i386, or around 6K text 1245 plus 16K runtime memory on x86-64, 1246 1247config X86_ESPFIX32 1248 def_bool y 1249 depends on X86_16BIT && X86_32 1250 1251config X86_ESPFIX64 1252 def_bool y 1253 depends on X86_16BIT && X86_64 1254 1255config X86_VSYSCALL_EMULATION 1256 bool "Enable vsyscall emulation" if EXPERT 1257 default y 1258 depends on X86_64 1259 help 1260 This enables emulation of the legacy vsyscall page. Disabling 1261 it is roughly equivalent to booting with vsyscall=none, except 1262 that it will also disable the helpful warning if a program 1263 tries to use a vsyscall. With this option set to N, offending 1264 programs will just segfault, citing addresses of the form 1265 0xffffffffff600?00. 1266 1267 This option is required by many programs built before 2013, and 1268 care should be used even with newer programs if set to N. 1269 1270 Disabling this option saves about 7K of kernel size and 1271 possibly 4K of additional runtime pagetable memory. 1272 1273config X86_IOPL_IOPERM 1274 bool "IOPERM and IOPL Emulation" 1275 default y 1276 help 1277 This enables the ioperm() and iopl() syscalls which are necessary 1278 for legacy applications. 1279 1280 Legacy IOPL support is an overbroad mechanism which allows user 1281 space aside of accessing all 65536 I/O ports also to disable 1282 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1283 capabilities and permission from potentially active security 1284 modules. 1285 1286 The emulation restricts the functionality of the syscall to 1287 only allowing the full range I/O port access, but prevents the 1288 ability to disable interrupts from user space which would be 1289 granted if the hardware IOPL mechanism would be used. 1290 1291config TOSHIBA 1292 tristate "Toshiba Laptop support" 1293 depends on X86_32 1294 help 1295 This adds a driver to safely access the System Management Mode of 1296 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1297 not work on models with a Phoenix BIOS. The System Management Mode 1298 is used to set the BIOS and power saving options on Toshiba portables. 1299 1300 For information on utilities to make use of this driver see the 1301 Toshiba Linux utilities web site at: 1302 <http://www.buzzard.org.uk/toshiba/>. 1303 1304 Say Y if you intend to run this kernel on a Toshiba portable. 1305 Say N otherwise. 1306 1307config X86_REBOOTFIXUPS 1308 bool "Enable X86 board specific fixups for reboot" 1309 depends on X86_32 1310 help 1311 This enables chipset and/or board specific fixups to be done 1312 in order to get reboot to work correctly. This is only needed on 1313 some combinations of hardware and BIOS. The symptom, for which 1314 this config is intended, is when reboot ends with a stalled/hung 1315 system. 1316 1317 Currently, the only fixup is for the Geode machines using 1318 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1319 1320 Say Y if you want to enable the fixup. Currently, it's safe to 1321 enable this option even if you don't need it. 1322 Say N otherwise. 1323 1324config MICROCODE 1325 def_bool y 1326 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1327 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD 1328 1329config MICROCODE_INITRD32 1330 def_bool y 1331 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1332 1333config MICROCODE_LATE_LOADING 1334 bool "Late microcode loading (DANGEROUS)" 1335 default n 1336 depends on MICROCODE && SMP 1337 help 1338 Loading microcode late, when the system is up and executing instructions 1339 is a tricky business and should be avoided if possible. Just the sequence 1340 of synchronizing all cores and SMT threads is one fragile dance which does 1341 not guarantee that cores might not softlock after the loading. Therefore, 1342 use this at your own risk. Late loading taints the kernel unless the 1343 microcode header indicates that it is safe for late loading via the 1344 minimal revision check. This minimal revision check can be enforced on 1345 the kernel command line with "microcode.minrev=Y". 1346 1347config MICROCODE_LATE_FORCE_MINREV 1348 bool "Enforce late microcode loading minimal revision check" 1349 default n 1350 depends on MICROCODE_LATE_LOADING 1351 help 1352 To prevent that users load microcode late which modifies already 1353 in use features, newer microcode patches have a minimum revision field 1354 in the microcode header, which tells the kernel which minimum 1355 revision must be active in the CPU to safely load that new microcode 1356 late into the running system. If disabled the check will not 1357 be enforced but the kernel will be tainted when the minimal 1358 revision check fails. 1359 1360 This minimal revision check can also be controlled via the 1361 "microcode.minrev" parameter on the kernel command line. 1362 1363 If unsure say Y. 1364 1365config X86_MSR 1366 tristate "/dev/cpu/*/msr - Model-specific register support" 1367 help 1368 This device gives privileged processes access to the x86 1369 Model-Specific Registers (MSRs). It is a character device with 1370 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1371 MSR accesses are directed to a specific CPU on multi-processor 1372 systems. 1373 1374config X86_CPUID 1375 tristate "/dev/cpu/*/cpuid - CPU information support" 1376 help 1377 This device gives processes access to the x86 CPUID instruction to 1378 be executed on a specific processor. It is a character device 1379 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1380 /dev/cpu/31/cpuid. 1381 1382config HIGHMEM4G 1383 bool "High Memory Support" 1384 depends on X86_32 1385 help 1386 Linux can use up to 4 Gigabytes of physical memory on x86 systems. 1387 However, the address space of 32-bit x86 processors is only 4 1388 Gigabytes large. That means that, if you have a large amount of 1389 physical memory, not all of it can be "permanently mapped" by the 1390 kernel. The physical memory that's not permanently mapped is called 1391 "high memory". 1392 1393 If you are compiling a kernel which will never run on a machine with 1394 more than 1 Gigabyte total physical RAM, answer "off" here (default 1395 choice and suitable for most users). This will result in a "3GB/1GB" 1396 split: 3GB are mapped so that each process sees a 3GB virtual memory 1397 space and the remaining part of the 4GB virtual memory space is used 1398 by the kernel to permanently map as much physical memory as 1399 possible. 1400 1401 If the machine has between 1 and 4 Gigabytes physical RAM, then 1402 answer "Y" here. 1403 1404 If unsure, say N. 1405 1406choice 1407 prompt "Memory split" if EXPERT 1408 default VMSPLIT_3G 1409 depends on X86_32 1410 help 1411 Select the desired split between kernel and user memory. 1412 1413 If the address range available to the kernel is less than the 1414 physical memory installed, the remaining memory will be available 1415 as "high memory". Accessing high memory is a little more costly 1416 than low memory, as it needs to be mapped into the kernel first. 1417 Note that increasing the kernel address space limits the range 1418 available to user programs, making the address space there 1419 tighter. Selecting anything other than the default 3G/1G split 1420 will also likely make your kernel incompatible with binary-only 1421 kernel modules. 1422 1423 If you are not absolutely sure what you are doing, leave this 1424 option alone! 1425 1426 config VMSPLIT_3G 1427 bool "3G/1G user/kernel split" 1428 config VMSPLIT_3G_OPT 1429 depends on !X86_PAE 1430 bool "3G/1G user/kernel split (for full 1G low memory)" 1431 config VMSPLIT_2G 1432 bool "2G/2G user/kernel split" 1433 config VMSPLIT_2G_OPT 1434 depends on !X86_PAE 1435 bool "2G/2G user/kernel split (for full 2G low memory)" 1436 config VMSPLIT_1G 1437 bool "1G/3G user/kernel split" 1438endchoice 1439 1440config PAGE_OFFSET 1441 hex 1442 default 0xB0000000 if VMSPLIT_3G_OPT 1443 default 0x80000000 if VMSPLIT_2G 1444 default 0x78000000 if VMSPLIT_2G_OPT 1445 default 0x40000000 if VMSPLIT_1G 1446 default 0xC0000000 1447 depends on X86_32 1448 1449config HIGHMEM 1450 def_bool HIGHMEM4G 1451 1452config X86_PAE 1453 bool "PAE (Physical Address Extension) Support" 1454 depends on X86_32 && X86_HAVE_PAE 1455 select PHYS_ADDR_T_64BIT 1456 help 1457 PAE is required for NX support, and furthermore enables 1458 larger swapspace support for non-overcommit purposes. It 1459 has the cost of more pagetable lookup overhead, and also 1460 consumes more pagetable space per process. 1461 1462config X86_DIRECT_GBPAGES 1463 def_bool y 1464 depends on X86_64 1465 help 1466 Certain kernel features effectively disable kernel 1467 linear 1 GB mappings (even if the CPU otherwise 1468 supports them), so don't confuse the user by printing 1469 that we have them enabled. 1470 1471config X86_CPA_STATISTICS 1472 bool "Enable statistic for Change Page Attribute" 1473 depends on DEBUG_FS 1474 help 1475 Expose statistics about the Change Page Attribute mechanism, which 1476 helps to determine the effectiveness of preserving large and huge 1477 page mappings when mapping protections are changed. 1478 1479config X86_MEM_ENCRYPT 1480 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1481 select DYNAMIC_PHYSICAL_MASK 1482 def_bool n 1483 1484config AMD_MEM_ENCRYPT 1485 bool "AMD Secure Memory Encryption (SME) support" 1486 depends on X86_64 && CPU_SUP_AMD 1487 depends on EFI_STUB 1488 select DMA_COHERENT_POOL 1489 select ARCH_USE_MEMREMAP_PROT 1490 select INSTRUCTION_DECODER 1491 select ARCH_HAS_CC_PLATFORM 1492 select X86_MEM_ENCRYPT 1493 select UNACCEPTED_MEMORY 1494 select CRYPTO_LIB_AESGCM 1495 help 1496 Say yes to enable support for the encryption of system memory. 1497 This requires an AMD processor that supports Secure Memory 1498 Encryption (SME). 1499 1500# Common NUMA Features 1501config NUMA 1502 bool "NUMA Memory Allocation and Scheduler Support" 1503 depends on SMP 1504 depends on X86_64 1505 select USE_PERCPU_NUMA_NODE_ID 1506 select OF_NUMA if OF 1507 help 1508 Enable NUMA (Non-Uniform Memory Access) support. 1509 1510 The kernel will try to allocate memory used by a CPU on the 1511 local memory controller of the CPU and add some more 1512 NUMA awareness to the kernel. 1513 1514 For 64-bit this is recommended if the system is Intel Core i7 1515 (or later), AMD Opteron, or EM64T NUMA. 1516 1517 Otherwise, you should say N. 1518 1519config AMD_NUMA 1520 def_bool y 1521 prompt "Old style AMD Opteron NUMA detection" 1522 depends on X86_64 && NUMA && PCI 1523 help 1524 Enable AMD NUMA node topology detection. You should say Y here if 1525 you have a multi processor AMD system. This uses an old method to 1526 read the NUMA configuration directly from the builtin Northbridge 1527 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1528 which also takes priority if both are compiled in. 1529 1530config X86_64_ACPI_NUMA 1531 def_bool y 1532 prompt "ACPI NUMA detection" 1533 depends on X86_64 && NUMA && ACPI && PCI 1534 select ACPI_NUMA 1535 help 1536 Enable ACPI SRAT based node topology detection. 1537 1538config NODES_SHIFT 1539 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1540 range 1 10 1541 default "10" if MAXSMP 1542 default "6" if X86_64 1543 default "3" 1544 depends on NUMA 1545 help 1546 Specify the maximum number of NUMA Nodes available on the target 1547 system. Increases memory reserved to accommodate various tables. 1548 1549config ARCH_FLATMEM_ENABLE 1550 def_bool y 1551 depends on X86_32 && !NUMA 1552 1553config ARCH_SPARSEMEM_ENABLE 1554 def_bool y 1555 select SPARSEMEM_STATIC if X86_32 1556 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1557 select SPARSEMEM_VMEMMAP if X86_64 1558 1559config ARCH_SPARSEMEM_DEFAULT 1560 def_bool X86_64 || (NUMA && X86_32) 1561 1562config ARCH_SELECT_MEMORY_MODEL 1563 def_bool y 1564 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1565 1566config ARCH_MEMORY_PROBE 1567 bool "Enable sysfs memory/probe interface" 1568 depends on MEMORY_HOTPLUG 1569 help 1570 This option enables a sysfs memory/probe interface for testing. 1571 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1572 If you are unsure how to answer this question, answer N. 1573 1574config ARCH_PROC_KCORE_TEXT 1575 def_bool y 1576 depends on X86_64 && PROC_KCORE 1577 1578config ILLEGAL_POINTER_VALUE 1579 hex 1580 default 0 if X86_32 1581 default 0xdead000000000000 if X86_64 1582 1583config X86_PMEM_LEGACY_DEVICE 1584 bool 1585 1586config X86_PMEM_LEGACY 1587 tristate "Support non-standard NVDIMMs and ADR protected memory" 1588 depends on PHYS_ADDR_T_64BIT 1589 depends on BLK_DEV 1590 select X86_PMEM_LEGACY_DEVICE 1591 select NUMA_KEEP_MEMINFO if NUMA 1592 select LIBNVDIMM 1593 help 1594 Treat memory marked using the non-standard e820 type of 12 as used 1595 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1596 The kernel will offer these regions to the 'pmem' driver so 1597 they can be used for persistent storage. 1598 1599 Say Y if unsure. 1600 1601config X86_CHECK_BIOS_CORRUPTION 1602 bool "Check for low memory corruption" 1603 help 1604 Periodically check for memory corruption in low memory, which 1605 is suspected to be caused by BIOS. Even when enabled in the 1606 configuration, it is disabled at runtime. Enable it by 1607 setting "memory_corruption_check=1" on the kernel command 1608 line. By default it scans the low 64k of memory every 60 1609 seconds; see the memory_corruption_check_size and 1610 memory_corruption_check_period parameters in 1611 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1612 1613 When enabled with the default parameters, this option has 1614 almost no overhead, as it reserves a relatively small amount 1615 of memory and scans it infrequently. It both detects corruption 1616 and prevents it from affecting the running system. 1617 1618 It is, however, intended as a diagnostic tool; if repeatable 1619 BIOS-originated corruption always affects the same memory, 1620 you can use memmap= to prevent the kernel from using that 1621 memory. 1622 1623config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1624 bool "Set the default setting of memory_corruption_check" 1625 depends on X86_CHECK_BIOS_CORRUPTION 1626 default y 1627 help 1628 Set whether the default state of memory_corruption_check is 1629 on or off. 1630 1631config MATH_EMULATION 1632 bool 1633 depends on MODIFY_LDT_SYSCALL 1634 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1635 help 1636 Linux can emulate a math coprocessor (used for floating point 1637 operations) if you don't have one. 486DX and Pentium processors have 1638 a math coprocessor built in, 486SX and 386 do not, unless you added 1639 a 487DX or 387, respectively. (The messages during boot time can 1640 give you some hints here ["man dmesg"].) Everyone needs either a 1641 coprocessor or this emulation. 1642 1643 If you don't have a math coprocessor, you need to say Y here; if you 1644 say Y here even though you have a coprocessor, the coprocessor will 1645 be used nevertheless. (This behavior can be changed with the kernel 1646 command line option "no387", which comes handy if your coprocessor 1647 is broken. Try "man bootparam" or see the documentation of your boot 1648 loader (lilo or loadlin) about how to pass options to the kernel at 1649 boot time.) This means that it is a good idea to say Y here if you 1650 intend to use this kernel on different machines. 1651 1652 More information about the internals of the Linux math coprocessor 1653 emulation can be found in <file:arch/x86/math-emu/README>. 1654 1655 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1656 kernel, it won't hurt. 1657 1658config MTRR 1659 def_bool y 1660 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1661 help 1662 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1663 the Memory Type Range Registers (MTRRs) may be used to control 1664 processor access to memory ranges. This is most useful if you have 1665 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1666 allows bus write transfers to be combined into a larger transfer 1667 before bursting over the PCI/AGP bus. This can increase performance 1668 of image write operations 2.5 times or more. Saying Y here creates a 1669 /proc/mtrr file which may be used to manipulate your processor's 1670 MTRRs. Typically the X server should use this. 1671 1672 This code has a reasonably generic interface so that similar 1673 control registers on other processors can be easily supported 1674 as well: 1675 1676 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1677 Registers (ARRs) which provide a similar functionality to MTRRs. For 1678 these, the ARRs are used to emulate the MTRRs. 1679 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1680 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1681 write-combining. All of these processors are supported by this code 1682 and it makes sense to say Y here if you have one of them. 1683 1684 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1685 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1686 can lead to all sorts of problems, so it's good to say Y here. 1687 1688 You can safely say Y even if your machine doesn't have MTRRs, you'll 1689 just add about 9 KB to your kernel. 1690 1691 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1692 1693config MTRR_SANITIZER 1694 def_bool y 1695 prompt "MTRR cleanup support" 1696 depends on MTRR 1697 help 1698 Convert MTRR layout from continuous to discrete, so X drivers can 1699 add writeback entries. 1700 1701 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1702 The largest mtrr entry size for a continuous block can be set with 1703 mtrr_chunk_size. 1704 1705 If unsure, say Y. 1706 1707config MTRR_SANITIZER_ENABLE_DEFAULT 1708 int "MTRR cleanup enable value (0-1)" 1709 range 0 1 1710 default "0" 1711 depends on MTRR_SANITIZER 1712 help 1713 Enable mtrr cleanup default value 1714 1715config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1716 int "MTRR cleanup spare reg num (0-7)" 1717 range 0 7 1718 default "1" 1719 depends on MTRR_SANITIZER 1720 help 1721 mtrr cleanup spare entries default, it can be changed via 1722 mtrr_spare_reg_nr=N on the kernel command line. 1723 1724config X86_PAT 1725 def_bool y 1726 prompt "x86 PAT support" if EXPERT 1727 depends on MTRR 1728 select ARCH_USES_PG_ARCH_2 1729 help 1730 Use PAT attributes to setup page level cache control. 1731 1732 PATs are the modern equivalents of MTRRs and are much more 1733 flexible than MTRRs. 1734 1735 Say N here if you see bootup problems (boot crash, boot hang, 1736 spontaneous reboots) or a non-working video driver. 1737 1738 If unsure, say Y. 1739 1740config X86_UMIP 1741 def_bool y 1742 prompt "User Mode Instruction Prevention" if EXPERT 1743 help 1744 User Mode Instruction Prevention (UMIP) is a security feature in 1745 some x86 processors. If enabled, a general protection fault is 1746 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1747 executed in user mode. These instructions unnecessarily expose 1748 information about the hardware state. 1749 1750 The vast majority of applications do not use these instructions. 1751 For the very few that do, software emulation is provided in 1752 specific cases in protected and virtual-8086 modes. Emulated 1753 results are dummy. 1754 1755config CC_HAS_IBT 1756 # GCC >= 9 and binutils >= 2.29 1757 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1758 # Clang/LLVM >= 14 1759 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1760 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1761 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1762 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1763 $(as-instr,endbr64) 1764 1765config X86_CET 1766 def_bool n 1767 help 1768 CET features configured (Shadow stack or IBT) 1769 1770config X86_KERNEL_IBT 1771 prompt "Indirect Branch Tracking" 1772 def_bool y 1773 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1774 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1775 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1776 select OBJTOOL 1777 select X86_CET 1778 help 1779 Build the kernel with support for Indirect Branch Tracking, a 1780 hardware support course-grain forward-edge Control Flow Integrity 1781 protection. It enforces that all indirect calls must land on 1782 an ENDBR instruction, as such, the compiler will instrument the 1783 code with them to make this happen. 1784 1785 In addition to building the kernel with IBT, seal all functions that 1786 are not indirect call targets, avoiding them ever becoming one. 1787 1788 This requires LTO like objtool runs and will slow down the build. It 1789 does significantly reduce the number of ENDBR instructions in the 1790 kernel image. 1791 1792config X86_INTEL_MEMORY_PROTECTION_KEYS 1793 prompt "Memory Protection Keys" 1794 def_bool y 1795 # Note: only available in 64-bit mode 1796 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1797 select ARCH_USES_HIGH_VMA_FLAGS 1798 select ARCH_HAS_PKEYS 1799 help 1800 Memory Protection Keys provides a mechanism for enforcing 1801 page-based protections, but without requiring modification of the 1802 page tables when an application changes protection domains. 1803 1804 For details, see Documentation/core-api/protection-keys.rst 1805 1806 If unsure, say y. 1807 1808config ARCH_PKEY_BITS 1809 int 1810 default 4 1811 1812choice 1813 prompt "TSX enable mode" 1814 depends on CPU_SUP_INTEL 1815 default X86_INTEL_TSX_MODE_OFF 1816 help 1817 Intel's TSX (Transactional Synchronization Extensions) feature 1818 allows to optimize locking protocols through lock elision which 1819 can lead to a noticeable performance boost. 1820 1821 On the other hand it has been shown that TSX can be exploited 1822 to form side channel attacks (e.g. TAA) and chances are there 1823 will be more of those attacks discovered in the future. 1824 1825 Therefore TSX is not enabled by default (aka tsx=off). An admin 1826 might override this decision by tsx=on the command line parameter. 1827 Even with TSX enabled, the kernel will attempt to enable the best 1828 possible TAA mitigation setting depending on the microcode available 1829 for the particular machine. 1830 1831 This option allows to set the default tsx mode between tsx=on, =off 1832 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1833 details. 1834 1835 Say off if not sure, auto if TSX is in use but it should be used on safe 1836 platforms or on if TSX is in use and the security aspect of tsx is not 1837 relevant. 1838 1839config X86_INTEL_TSX_MODE_OFF 1840 bool "off" 1841 help 1842 TSX is disabled if possible - equals to tsx=off command line parameter. 1843 1844config X86_INTEL_TSX_MODE_ON 1845 bool "on" 1846 help 1847 TSX is always enabled on TSX capable HW - equals the tsx=on command 1848 line parameter. 1849 1850config X86_INTEL_TSX_MODE_AUTO 1851 bool "auto" 1852 help 1853 TSX is enabled on TSX capable HW that is believed to be safe against 1854 side channel attacks- equals the tsx=auto command line parameter. 1855endchoice 1856 1857config X86_SGX 1858 bool "Software Guard eXtensions (SGX)" 1859 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1860 select CRYPTO_LIB_SHA256 1861 select MMU_NOTIFIER 1862 select NUMA_KEEP_MEMINFO if NUMA 1863 select XARRAY_MULTI 1864 help 1865 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1866 that can be used by applications to set aside private regions of code 1867 and data, referred to as enclaves. An enclave's private memory can 1868 only be accessed by code running within the enclave. Accesses from 1869 outside the enclave, including other enclaves, are disallowed by 1870 hardware. 1871 1872 If unsure, say N. 1873 1874config X86_USER_SHADOW_STACK 1875 bool "X86 userspace shadow stack" 1876 depends on AS_WRUSS 1877 depends on X86_64 1878 select ARCH_USES_HIGH_VMA_FLAGS 1879 select ARCH_HAS_USER_SHADOW_STACK 1880 select X86_CET 1881 help 1882 Shadow stack protection is a hardware feature that detects function 1883 return address corruption. This helps mitigate ROP attacks. 1884 Applications must be enabled to use it, and old userspace does not 1885 get protection "for free". 1886 1887 CPUs supporting shadow stacks were first released in 2020. 1888 1889 See Documentation/arch/x86/shstk.rst for more information. 1890 1891 If unsure, say N. 1892 1893config INTEL_TDX_HOST 1894 bool "Intel Trust Domain Extensions (TDX) host support" 1895 depends on CPU_SUP_INTEL 1896 depends on X86_64 1897 depends on KVM_INTEL 1898 depends on X86_X2APIC 1899 select ARCH_KEEP_MEMBLOCK 1900 depends on CONTIG_ALLOC 1901 depends on !KEXEC_CORE 1902 depends on X86_MCE 1903 help 1904 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1905 host and certain physical attacks. This option enables necessary TDX 1906 support in the host kernel to run confidential VMs. 1907 1908 If unsure, say N. 1909 1910config EFI 1911 bool "EFI runtime service support" 1912 depends on ACPI 1913 select UCS2_STRING 1914 select EFI_RUNTIME_WRAPPERS 1915 select ARCH_USE_MEMREMAP_PROT 1916 select EFI_RUNTIME_MAP if KEXEC_CORE 1917 help 1918 This enables the kernel to use EFI runtime services that are 1919 available (such as the EFI variable services). 1920 1921 This option is only useful on systems that have EFI firmware. 1922 In addition, you should use the latest ELILO loader available 1923 at <http://elilo.sourceforge.net> in order to take advantage 1924 of EFI runtime services. However, even with this option, the 1925 resultant kernel should continue to boot on existing non-EFI 1926 platforms. 1927 1928config EFI_STUB 1929 bool "EFI stub support" 1930 depends on EFI 1931 select RELOCATABLE 1932 help 1933 This kernel feature allows a bzImage to be loaded directly 1934 by EFI firmware without the use of a bootloader. 1935 1936 See Documentation/admin-guide/efi-stub.rst for more information. 1937 1938config EFI_HANDOVER_PROTOCOL 1939 bool "EFI handover protocol (DEPRECATED)" 1940 depends on EFI_STUB 1941 default y 1942 help 1943 Select this in order to include support for the deprecated EFI 1944 handover protocol, which defines alternative entry points into the 1945 EFI stub. This is a practice that has no basis in the UEFI 1946 specification, and requires a priori knowledge on the part of the 1947 bootloader about Linux/x86 specific ways of passing the command line 1948 and initrd, and where in memory those assets may be loaded. 1949 1950 If in doubt, say Y. Even though the corresponding support is not 1951 present in upstream GRUB or other bootloaders, most distros build 1952 GRUB with numerous downstream patches applied, and may rely on the 1953 handover protocol as as result. 1954 1955config EFI_MIXED 1956 bool "EFI mixed-mode support" 1957 depends on EFI_STUB && X86_64 1958 help 1959 Enabling this feature allows a 64-bit kernel to be booted 1960 on a 32-bit firmware, provided that your CPU supports 64-bit 1961 mode. 1962 1963 Note that it is not possible to boot a mixed-mode enabled 1964 kernel via the EFI boot stub - a bootloader that supports 1965 the EFI handover protocol must be used. 1966 1967 If unsure, say N. 1968 1969config EFI_RUNTIME_MAP 1970 bool "Export EFI runtime maps to sysfs" if EXPERT 1971 depends on EFI 1972 help 1973 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 1974 That memory map is required by the 2nd kernel to set up EFI virtual 1975 mappings after kexec, but can also be used for debugging purposes. 1976 1977 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 1978 1979source "kernel/Kconfig.hz" 1980 1981config ARCH_SUPPORTS_KEXEC 1982 def_bool y 1983 1984config ARCH_SUPPORTS_KEXEC_FILE 1985 def_bool X86_64 1986 1987config ARCH_SELECTS_KEXEC_FILE 1988 def_bool y 1989 depends on KEXEC_FILE 1990 select HAVE_IMA_KEXEC if IMA 1991 1992config ARCH_SUPPORTS_KEXEC_PURGATORY 1993 def_bool y 1994 1995config ARCH_SUPPORTS_KEXEC_SIG 1996 def_bool y 1997 1998config ARCH_SUPPORTS_KEXEC_SIG_FORCE 1999 def_bool y 2000 2001config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2002 def_bool y 2003 2004config ARCH_SUPPORTS_KEXEC_JUMP 2005 def_bool y 2006 2007config ARCH_SUPPORTS_KEXEC_HANDOVER 2008 def_bool X86_64 2009 2010config ARCH_SUPPORTS_CRASH_DUMP 2011 def_bool X86_64 || (X86_32 && HIGHMEM) 2012 2013config ARCH_DEFAULT_CRASH_DUMP 2014 def_bool y 2015 2016config ARCH_SUPPORTS_CRASH_HOTPLUG 2017 def_bool y 2018 2019config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2020 def_bool CRASH_RESERVE 2021 2022config PHYSICAL_START 2023 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2024 default "0x1000000" 2025 help 2026 This gives the physical address where the kernel is loaded. 2027 2028 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2029 will decompress itself to above physical address and run from there. 2030 Otherwise, bzImage will run from the address where it has been loaded 2031 by the boot loader. The only exception is if it is loaded below the 2032 above physical address, in which case it will relocate itself there. 2033 2034 In normal kdump cases one does not have to set/change this option 2035 as now bzImage can be compiled as a completely relocatable image 2036 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2037 address. This option is mainly useful for the folks who don't want 2038 to use a bzImage for capturing the crash dump and want to use a 2039 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2040 to be specifically compiled to run from a specific memory area 2041 (normally a reserved region) and this option comes handy. 2042 2043 So if you are using bzImage for capturing the crash dump, 2044 leave the value here unchanged to 0x1000000 and set 2045 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2046 for capturing the crash dump change this value to start of 2047 the reserved region. In other words, it can be set based on 2048 the "X" value as specified in the "crashkernel=YM@XM" 2049 command line boot parameter passed to the panic-ed 2050 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2051 for more details about crash dumps. 2052 2053 Usage of bzImage for capturing the crash dump is recommended as 2054 one does not have to build two kernels. Same kernel can be used 2055 as production kernel and capture kernel. Above option should have 2056 gone away after relocatable bzImage support is introduced. But it 2057 is present because there are users out there who continue to use 2058 vmlinux for dump capture. This option should go away down the 2059 line. 2060 2061 Don't change this unless you know what you are doing. 2062 2063config RELOCATABLE 2064 bool "Build a relocatable kernel" 2065 default y 2066 help 2067 This builds a kernel image that retains relocation information 2068 so it can be loaded someplace besides the default 1MB. 2069 The relocations tend to make the kernel binary about 10% larger, 2070 but are discarded at runtime. 2071 2072 One use is for the kexec on panic case where the recovery kernel 2073 must live at a different physical address than the primary 2074 kernel. 2075 2076 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2077 it has been loaded at and the compile time physical address 2078 (CONFIG_PHYSICAL_START) is used as the minimum location. 2079 2080config RANDOMIZE_BASE 2081 bool "Randomize the address of the kernel image (KASLR)" 2082 depends on RELOCATABLE 2083 default y 2084 help 2085 In support of Kernel Address Space Layout Randomization (KASLR), 2086 this randomizes the physical address at which the kernel image 2087 is decompressed and the virtual address where the kernel 2088 image is mapped, as a security feature that deters exploit 2089 attempts relying on knowledge of the location of kernel 2090 code internals. 2091 2092 On 64-bit, the kernel physical and virtual addresses are 2093 randomized separately. The physical address will be anywhere 2094 between 16MB and the top of physical memory (up to 64TB). The 2095 virtual address will be randomized from 16MB up to 1GB (9 bits 2096 of entropy). Note that this also reduces the memory space 2097 available to kernel modules from 1.5GB to 1GB. 2098 2099 On 32-bit, the kernel physical and virtual addresses are 2100 randomized together. They will be randomized from 16MB up to 2101 512MB (8 bits of entropy). 2102 2103 Entropy is generated using the RDRAND instruction if it is 2104 supported. If RDTSC is supported, its value is mixed into 2105 the entropy pool as well. If neither RDRAND nor RDTSC are 2106 supported, then entropy is read from the i8254 timer. The 2107 usable entropy is limited by the kernel being built using 2108 2GB addressing, and that PHYSICAL_ALIGN must be at a 2109 minimum of 2MB. As a result, only 10 bits of entropy are 2110 theoretically possible, but the implementations are further 2111 limited due to memory layouts. 2112 2113 If unsure, say Y. 2114 2115# Relocation on x86 needs some additional build support 2116config X86_NEED_RELOCS 2117 def_bool y 2118 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2119 select ARCH_VMLINUX_NEEDS_RELOCS 2120 2121config PHYSICAL_ALIGN 2122 hex "Alignment value to which kernel should be aligned" 2123 default "0x200000" 2124 range 0x2000 0x1000000 if X86_32 2125 range 0x200000 0x1000000 if X86_64 2126 help 2127 This value puts the alignment restrictions on physical address 2128 where kernel is loaded and run from. Kernel is compiled for an 2129 address which meets above alignment restriction. 2130 2131 If bootloader loads the kernel at a non-aligned address and 2132 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2133 address aligned to above value and run from there. 2134 2135 If bootloader loads the kernel at a non-aligned address and 2136 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2137 load address and decompress itself to the address it has been 2138 compiled for and run from there. The address for which kernel is 2139 compiled already meets above alignment restrictions. Hence the 2140 end result is that kernel runs from a physical address meeting 2141 above alignment restrictions. 2142 2143 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2144 this value must be a multiple of 0x200000. 2145 2146 Don't change this unless you know what you are doing. 2147 2148config RANDOMIZE_MEMORY 2149 bool "Randomize the kernel memory sections" 2150 depends on X86_64 2151 depends on RANDOMIZE_BASE 2152 default RANDOMIZE_BASE 2153 help 2154 Randomizes the base virtual address of kernel memory sections 2155 (physical memory mapping, vmalloc & vmemmap). This security feature 2156 makes exploits relying on predictable memory locations less reliable. 2157 2158 The order of allocations remains unchanged. Entropy is generated in 2159 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2160 configuration have in average 30,000 different possible virtual 2161 addresses for each memory section. 2162 2163 If unsure, say Y. 2164 2165config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2166 hex "Physical memory mapping padding" if EXPERT 2167 depends on RANDOMIZE_MEMORY 2168 default "0xa" if MEMORY_HOTPLUG 2169 default "0x0" 2170 range 0x1 0x40 if MEMORY_HOTPLUG 2171 range 0x0 0x40 2172 help 2173 Define the padding in terabytes added to the existing physical 2174 memory size during kernel memory randomization. It is useful 2175 for memory hotplug support but reduces the entropy available for 2176 address randomization. 2177 2178 If unsure, leave at the default value. 2179 2180config ADDRESS_MASKING 2181 bool "Linear Address Masking support" 2182 depends on X86_64 2183 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2184 help 2185 Linear Address Masking (LAM) modifies the checking that is applied 2186 to 64-bit linear addresses, allowing software to use of the 2187 untranslated address bits for metadata. 2188 2189 The capability can be used for efficient address sanitizers (ASAN) 2190 implementation and for optimizations in JITs. 2191 2192config HOTPLUG_CPU 2193 def_bool y 2194 depends on SMP 2195 2196config COMPAT_VDSO 2197 def_bool n 2198 prompt "Workaround for glibc 2.3.2 / 2.3.3 (released in year 2003/2004)" 2199 depends on COMPAT_32 2200 help 2201 Certain buggy versions of glibc will crash if they are 2202 presented with a 32-bit vDSO that is not mapped at the address 2203 indicated in its segment table. 2204 2205 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2206 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2207 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2208 the only released version with the bug, but OpenSUSE 9 2209 contains a buggy "glibc 2.3.2". 2210 2211 The symptom of the bug is that everything crashes on startup, saying: 2212 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2213 2214 Saying Y here changes the default value of the vdso32 boot 2215 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2216 This works around the glibc bug but hurts performance. 2217 2218 If unsure, say N: if you are compiling your own kernel, you 2219 are unlikely to be using a buggy version of glibc. 2220 2221choice 2222 prompt "vsyscall table for legacy applications" 2223 depends on X86_64 2224 default LEGACY_VSYSCALL_XONLY 2225 help 2226 Legacy user code that does not know how to find the vDSO expects 2227 to be able to issue three syscalls by calling fixed addresses in 2228 kernel space. Since this location is not randomized with ASLR, 2229 it can be used to assist security vulnerability exploitation. 2230 2231 This setting can be changed at boot time via the kernel command 2232 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2233 is deprecated and can only be enabled using the kernel command 2234 line. 2235 2236 On a system with recent enough glibc (2.14 or newer) and no 2237 static binaries, you can say None without a performance penalty 2238 to improve security. 2239 2240 If unsure, select "Emulate execution only". 2241 2242 config LEGACY_VSYSCALL_XONLY 2243 bool "Emulate execution only" 2244 help 2245 The kernel traps and emulates calls into the fixed vsyscall 2246 address mapping and does not allow reads. This 2247 configuration is recommended when userspace might use the 2248 legacy vsyscall area but support for legacy binary 2249 instrumentation of legacy code is not needed. It mitigates 2250 certain uses of the vsyscall area as an ASLR-bypassing 2251 buffer. 2252 2253 config LEGACY_VSYSCALL_NONE 2254 bool "None" 2255 help 2256 There will be no vsyscall mapping at all. This will 2257 eliminate any risk of ASLR bypass due to the vsyscall 2258 fixed address mapping. Attempts to use the vsyscalls 2259 will be reported to dmesg, so that either old or 2260 malicious userspace programs can be identified. 2261 2262endchoice 2263 2264config CMDLINE_BOOL 2265 bool "Built-in kernel command line" 2266 help 2267 Allow for specifying boot arguments to the kernel at 2268 build time. On some systems (e.g. embedded ones), it is 2269 necessary or convenient to provide some or all of the 2270 kernel boot arguments with the kernel itself (that is, 2271 to not rely on the boot loader to provide them.) 2272 2273 To compile command line arguments into the kernel, 2274 set this option to 'Y', then fill in the 2275 boot arguments in CONFIG_CMDLINE. 2276 2277 Systems with fully functional boot loaders (i.e. non-embedded) 2278 should leave this option set to 'N'. 2279 2280config CMDLINE 2281 string "Built-in kernel command string" 2282 depends on CMDLINE_BOOL 2283 default "" 2284 help 2285 Enter arguments here that should be compiled into the kernel 2286 image and used at boot time. If the boot loader provides a 2287 command line at boot time, it is appended to this string to 2288 form the full kernel command line, when the system boots. 2289 2290 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2291 change this behavior. 2292 2293 In most cases, the command line (whether built-in or provided 2294 by the boot loader) should specify the device for the root 2295 file system. 2296 2297config CMDLINE_OVERRIDE 2298 bool "Built-in command line overrides boot loader arguments" 2299 depends on CMDLINE_BOOL && CMDLINE != "" 2300 help 2301 Set this option to 'Y' to have the kernel ignore the boot loader 2302 command line, and use ONLY the built-in command line. 2303 2304 This is used to work around broken boot loaders. This should 2305 be set to 'N' under normal conditions. 2306 2307config MODIFY_LDT_SYSCALL 2308 bool "Enable the LDT (local descriptor table)" if EXPERT 2309 default y 2310 help 2311 Linux can allow user programs to install a per-process x86 2312 Local Descriptor Table (LDT) using the modify_ldt(2) system 2313 call. This is required to run 16-bit or segmented code such as 2314 DOSEMU or some Wine programs. It is also used by some very old 2315 threading libraries. 2316 2317 Enabling this feature adds a small amount of overhead to 2318 context switches and increases the low-level kernel attack 2319 surface. Disabling it removes the modify_ldt(2) system call. 2320 2321 Saying 'N' here may make sense for embedded or server kernels. 2322 2323config STRICT_SIGALTSTACK_SIZE 2324 bool "Enforce strict size checking for sigaltstack" 2325 depends on DYNAMIC_SIGFRAME 2326 help 2327 For historical reasons MINSIGSTKSZ is a constant which became 2328 already too small with AVX512 support. Add a mechanism to 2329 enforce strict checking of the sigaltstack size against the 2330 real size of the FPU frame. This option enables the check 2331 by default. It can also be controlled via the kernel command 2332 line option 'strict_sas_size' independent of this config 2333 switch. Enabling it might break existing applications which 2334 allocate a too small sigaltstack but 'work' because they 2335 never get a signal delivered. 2336 2337 Say 'N' unless you want to really enforce this check. 2338 2339config CFI_AUTO_DEFAULT 2340 bool "Attempt to use FineIBT by default at boot time" 2341 depends on FINEIBT 2342 depends on !RUST || RUSTC_VERSION >= 108800 2343 default y 2344 help 2345 Attempt to use FineIBT by default at boot time. If enabled, 2346 this is the same as booting with "cfi=auto". If disabled, 2347 this is the same as booting with "cfi=kcfi". 2348 2349source "kernel/livepatch/Kconfig" 2350 2351config X86_BUS_LOCK_DETECT 2352 bool "Split Lock Detect and Bus Lock Detect support" 2353 depends on CPU_SUP_INTEL || CPU_SUP_AMD 2354 default y 2355 help 2356 Enable Split Lock Detect and Bus Lock Detect functionalities. 2357 See <file:Documentation/arch/x86/buslock.rst> for more information. 2358 2359endmenu 2360 2361config CC_HAS_NAMED_AS 2362 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null) 2363 depends on CC_IS_GCC 2364 2365# 2366# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN) 2367# are incompatible with named address spaces with GCC < 13.3 2368# (see GCC PR sanitizer/111736 and also PR sanitizer/115172). 2369# 2370 2371config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2372 def_bool y 2373 depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300 2374 depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200 2375 2376config USE_X86_SEG_SUPPORT 2377 def_bool CC_HAS_NAMED_AS 2378 depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS 2379 2380config CC_HAS_SLS 2381 def_bool $(cc-option,-mharden-sls=all) 2382 2383config CC_HAS_RETURN_THUNK 2384 def_bool $(cc-option,-mfunction-return=thunk-extern) 2385 2386config CC_HAS_ENTRY_PADDING 2387 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2388 2389config CC_HAS_KCFI_ARITY 2390 def_bool $(cc-option,-fsanitize=kcfi -fsanitize-kcfi-arity) 2391 depends on CC_IS_CLANG && !RUST 2392 2393config FUNCTION_PADDING_CFI 2394 int 2395 default 59 if FUNCTION_ALIGNMENT_64B 2396 default 27 if FUNCTION_ALIGNMENT_32B 2397 default 11 if FUNCTION_ALIGNMENT_16B 2398 default 3 if FUNCTION_ALIGNMENT_8B 2399 default 0 2400 2401# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2402# except Kconfig can't do arithmetic :/ 2403config FUNCTION_PADDING_BYTES 2404 int 2405 default FUNCTION_PADDING_CFI if CFI_CLANG 2406 default FUNCTION_ALIGNMENT 2407 2408config CALL_PADDING 2409 def_bool n 2410 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2411 select FUNCTION_ALIGNMENT_16B 2412 2413config FINEIBT 2414 def_bool y 2415 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE 2416 select CALL_PADDING 2417 2418config FINEIBT_BHI 2419 def_bool y 2420 depends on FINEIBT && CC_HAS_KCFI_ARITY 2421 2422config HAVE_CALL_THUNKS 2423 def_bool y 2424 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2425 2426config CALL_THUNKS 2427 def_bool n 2428 select CALL_PADDING 2429 2430config PREFIX_SYMBOLS 2431 def_bool y 2432 depends on CALL_PADDING && !CFI_CLANG 2433 2434menuconfig CPU_MITIGATIONS 2435 bool "Mitigations for CPU vulnerabilities" 2436 default y 2437 help 2438 Say Y here to enable options which enable mitigations for hardware 2439 vulnerabilities (usually related to speculative execution). 2440 Mitigations can be disabled or restricted to SMT systems at runtime 2441 via the "mitigations" kernel parameter. 2442 2443 If you say N, all mitigations will be disabled. This CANNOT be 2444 overridden at runtime. 2445 2446 Say 'Y', unless you really know what you are doing. 2447 2448if CPU_MITIGATIONS 2449 2450config MITIGATION_PAGE_TABLE_ISOLATION 2451 bool "Remove the kernel mapping in user mode" 2452 default y 2453 depends on (X86_64 || X86_PAE) 2454 help 2455 This feature reduces the number of hardware side channels by 2456 ensuring that the majority of kernel addresses are not mapped 2457 into userspace. 2458 2459 See Documentation/arch/x86/pti.rst for more details. 2460 2461config MITIGATION_RETPOLINE 2462 bool "Avoid speculative indirect branches in kernel" 2463 select OBJTOOL if HAVE_OBJTOOL 2464 default y 2465 help 2466 Compile kernel with the retpoline compiler options to guard against 2467 kernel-to-user data leaks by avoiding speculative indirect 2468 branches. Requires a compiler with -mindirect-branch=thunk-extern 2469 support for full protection. The kernel may run slower. 2470 2471config MITIGATION_RETHUNK 2472 bool "Enable return-thunks" 2473 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2474 select OBJTOOL if HAVE_OBJTOOL 2475 default y if X86_64 2476 help 2477 Compile the kernel with the return-thunks compiler option to guard 2478 against kernel-to-user data leaks by avoiding return speculation. 2479 Requires a compiler with -mfunction-return=thunk-extern 2480 support for full protection. The kernel may run slower. 2481 2482config MITIGATION_UNRET_ENTRY 2483 bool "Enable UNRET on kernel entry" 2484 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2485 default y 2486 help 2487 Compile the kernel with support for the retbleed=unret mitigation. 2488 2489config MITIGATION_CALL_DEPTH_TRACKING 2490 bool "Mitigate RSB underflow with call depth tracking" 2491 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2492 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2493 select CALL_THUNKS 2494 default y 2495 help 2496 Compile the kernel with call depth tracking to mitigate the Intel 2497 SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off 2498 by default and needs to be enabled on the kernel command line via the 2499 retbleed=stuff option. For non-affected systems the overhead of this 2500 option is marginal as the call depth tracking is using run-time 2501 generated call thunks in a compiler generated padding area and call 2502 patching. This increases text size by ~5%. For non affected systems 2503 this space is unused. On affected SKL systems this results in a 2504 significant performance gain over the IBRS mitigation. 2505 2506config CALL_THUNKS_DEBUG 2507 bool "Enable call thunks and call depth tracking debugging" 2508 depends on MITIGATION_CALL_DEPTH_TRACKING 2509 select FUNCTION_ALIGNMENT_32B 2510 default n 2511 help 2512 Enable call/ret counters for imbalance detection and build in 2513 a noisy dmesg about callthunks generation and call patching for 2514 trouble shooting. The debug prints need to be enabled on the 2515 kernel command line with 'debug-callthunks'. 2516 Only enable this when you are debugging call thunks as this 2517 creates a noticeable runtime overhead. If unsure say N. 2518 2519config MITIGATION_IBPB_ENTRY 2520 bool "Enable IBPB on kernel entry" 2521 depends on CPU_SUP_AMD && X86_64 2522 default y 2523 help 2524 Compile the kernel with support for the retbleed=ibpb and 2525 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations. 2526 2527config MITIGATION_IBRS_ENTRY 2528 bool "Enable IBRS on kernel entry" 2529 depends on CPU_SUP_INTEL && X86_64 2530 default y 2531 help 2532 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2533 This mitigates both spectre_v2 and retbleed at great cost to 2534 performance. 2535 2536config MITIGATION_SRSO 2537 bool "Mitigate speculative RAS overflow on AMD" 2538 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2539 default y 2540 help 2541 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2542 2543config MITIGATION_SLS 2544 bool "Mitigate Straight-Line-Speculation" 2545 depends on CC_HAS_SLS && X86_64 2546 select OBJTOOL if HAVE_OBJTOOL 2547 default n 2548 help 2549 Compile the kernel with straight-line-speculation options to guard 2550 against straight line speculation. The kernel image might be slightly 2551 larger. 2552 2553config MITIGATION_GDS 2554 bool "Mitigate Gather Data Sampling" 2555 depends on CPU_SUP_INTEL 2556 default y 2557 help 2558 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware 2559 vulnerability which allows unprivileged speculative access to data 2560 which was previously stored in vector registers. The attacker uses gather 2561 instructions to infer the stale vector register data. 2562 2563config MITIGATION_RFDS 2564 bool "RFDS Mitigation" 2565 depends on CPU_SUP_INTEL 2566 default y 2567 help 2568 Enable mitigation for Register File Data Sampling (RFDS) by default. 2569 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2570 allows unprivileged speculative access to stale data previously 2571 stored in floating point, vector and integer registers. 2572 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2573 2574config MITIGATION_SPECTRE_BHI 2575 bool "Mitigate Spectre-BHB (Branch History Injection)" 2576 depends on CPU_SUP_INTEL 2577 default y 2578 help 2579 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2580 where the branch history buffer is poisoned to speculatively steer 2581 indirect branches. 2582 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2583 2584config MITIGATION_MDS 2585 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug" 2586 depends on CPU_SUP_INTEL 2587 default y 2588 help 2589 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is 2590 a hardware vulnerability which allows unprivileged speculative access 2591 to data which is available in various CPU internal buffers. 2592 See also <file:Documentation/admin-guide/hw-vuln/mds.rst> 2593 2594config MITIGATION_TAA 2595 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug" 2596 depends on CPU_SUP_INTEL 2597 default y 2598 help 2599 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware 2600 vulnerability that allows unprivileged speculative access to data 2601 which is available in various CPU internal buffers by using 2602 asynchronous aborts within an Intel TSX transactional region. 2603 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst> 2604 2605config MITIGATION_MMIO_STALE_DATA 2606 bool "Mitigate MMIO Stale Data hardware bug" 2607 depends on CPU_SUP_INTEL 2608 default y 2609 help 2610 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO 2611 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO) 2612 vulnerabilities that can expose data. The vulnerabilities require the 2613 attacker to have access to MMIO. 2614 See also 2615 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst> 2616 2617config MITIGATION_L1TF 2618 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug" 2619 depends on CPU_SUP_INTEL 2620 default y 2621 help 2622 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a 2623 hardware vulnerability which allows unprivileged speculative access to data 2624 available in the Level 1 Data Cache. 2625 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst 2626 2627config MITIGATION_RETBLEED 2628 bool "Mitigate RETBleed hardware bug" 2629 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY 2630 default y 2631 help 2632 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution 2633 with Return Instructions) vulnerability. RETBleed is a speculative 2634 execution attack which takes advantage of microarchitectural behavior 2635 in many modern microprocessors, similar to Spectre v2. An 2636 unprivileged attacker can use these flaws to bypass conventional 2637 memory security restrictions to gain read access to privileged memory 2638 that would otherwise be inaccessible. 2639 2640config MITIGATION_SPECTRE_V1 2641 bool "Mitigate SPECTRE V1 hardware bug" 2642 default y 2643 help 2644 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a 2645 class of side channel attacks that takes advantage of speculative 2646 execution that bypasses conditional branch instructions used for 2647 memory access bounds check. 2648 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2649 2650config MITIGATION_SPECTRE_V2 2651 bool "Mitigate SPECTRE V2 hardware bug" 2652 default y 2653 help 2654 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre 2655 V2 is a class of side channel attacks that takes advantage of 2656 indirect branch predictors inside the processor. In Spectre variant 2 2657 attacks, the attacker can steer speculative indirect branches in the 2658 victim to gadget code by poisoning the branch target buffer of a CPU 2659 used for predicting indirect branch addresses. 2660 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2661 2662config MITIGATION_SRBDS 2663 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug" 2664 depends on CPU_SUP_INTEL 2665 default y 2666 help 2667 Enable mitigation for Special Register Buffer Data Sampling (SRBDS). 2668 SRBDS is a hardware vulnerability that allows Microarchitectural Data 2669 Sampling (MDS) techniques to infer values returned from special 2670 register accesses. An unprivileged user can extract values returned 2671 from RDRAND and RDSEED executed on another core or sibling thread 2672 using MDS techniques. 2673 See also 2674 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst> 2675 2676config MITIGATION_SSB 2677 bool "Mitigate Speculative Store Bypass (SSB) hardware bug" 2678 default y 2679 help 2680 Enable mitigation for Speculative Store Bypass (SSB). SSB is a 2681 hardware security vulnerability and its exploitation takes advantage 2682 of speculative execution in a similar way to the Meltdown and Spectre 2683 security vulnerabilities. 2684 2685config MITIGATION_ITS 2686 bool "Enable Indirect Target Selection mitigation" 2687 depends on CPU_SUP_INTEL && X86_64 2688 depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK 2689 select EXECMEM 2690 default y 2691 help 2692 Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in 2693 BPU on some Intel CPUs that may allow Spectre V2 style attacks. If 2694 disabled, mitigation cannot be enabled via cmdline. 2695 See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst> 2696 2697endif 2698 2699config ARCH_HAS_ADD_PAGES 2700 def_bool y 2701 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2702 2703menu "Power management and ACPI options" 2704 2705config ARCH_HIBERNATION_HEADER 2706 def_bool y 2707 depends on HIBERNATION 2708 2709source "kernel/power/Kconfig" 2710 2711source "drivers/acpi/Kconfig" 2712 2713config X86_APM_BOOT 2714 def_bool y 2715 depends on APM 2716 2717menuconfig APM 2718 tristate "APM (Advanced Power Management) BIOS support" 2719 depends on X86_32 && PM_SLEEP 2720 help 2721 APM is a BIOS specification for saving power using several different 2722 techniques. This is mostly useful for battery powered laptops with 2723 APM compliant BIOSes. If you say Y here, the system time will be 2724 reset after a RESUME operation, the /proc/apm device will provide 2725 battery status information, and user-space programs will receive 2726 notification of APM "events" (e.g. battery status change). 2727 2728 If you select "Y" here, you can disable actual use of the APM 2729 BIOS by passing the "apm=off" option to the kernel at boot time. 2730 2731 Note that the APM support is almost completely disabled for 2732 machines with more than one CPU. 2733 2734 In order to use APM, you will need supporting software. For location 2735 and more information, read <file:Documentation/power/apm-acpi.rst> 2736 and the Battery Powered Linux mini-HOWTO, available from 2737 <http://www.tldp.org/docs.html#howto>. 2738 2739 This driver does not spin down disk drives (see the hdparm(8) 2740 manpage ("man 8 hdparm") for that), and it doesn't turn off 2741 VESA-compliant "green" monitors. 2742 2743 This driver does not support the TI 4000M TravelMate and the ACER 2744 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2745 desktop machines also don't have compliant BIOSes, and this driver 2746 may cause those machines to panic during the boot phase. 2747 2748 Generally, if you don't have a battery in your machine, there isn't 2749 much point in using this driver and you should say N. If you get 2750 random kernel OOPSes or reboots that don't seem to be related to 2751 anything, try disabling/enabling this option (or disabling/enabling 2752 APM in your BIOS). 2753 2754 Some other things you should try when experiencing seemingly random, 2755 "weird" problems: 2756 2757 1) make sure that you have enough swap space and that it is 2758 enabled. 2759 2) pass the "idle=poll" option to the kernel 2760 3) switch on floating point emulation in the kernel and pass 2761 the "no387" option to the kernel 2762 4) pass the "floppy=nodma" option to the kernel 2763 5) pass the "mem=4M" option to the kernel (thereby disabling 2764 all but the first 4 MB of RAM) 2765 6) make sure that the CPU is not over clocked. 2766 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2767 8) disable the cache from your BIOS settings 2768 9) install a fan for the video card or exchange video RAM 2769 10) install a better fan for the CPU 2770 11) exchange RAM chips 2771 12) exchange the motherboard. 2772 2773 To compile this driver as a module, choose M here: the 2774 module will be called apm. 2775 2776if APM 2777 2778config APM_IGNORE_USER_SUSPEND 2779 bool "Ignore USER SUSPEND" 2780 help 2781 This option will ignore USER SUSPEND requests. On machines with a 2782 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2783 series notebooks, it is necessary to say Y because of a BIOS bug. 2784 2785config APM_DO_ENABLE 2786 bool "Enable PM at boot time" 2787 help 2788 Enable APM features at boot time. From page 36 of the APM BIOS 2789 specification: "When disabled, the APM BIOS does not automatically 2790 power manage devices, enter the Standby State, enter the Suspend 2791 State, or take power saving steps in response to CPU Idle calls." 2792 This driver will make CPU Idle calls when Linux is idle (unless this 2793 feature is turned off -- see "Do CPU IDLE calls", below). This 2794 should always save battery power, but more complicated APM features 2795 will be dependent on your BIOS implementation. You may need to turn 2796 this option off if your computer hangs at boot time when using APM 2797 support, or if it beeps continuously instead of suspending. Turn 2798 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2799 T400CDT. This is off by default since most machines do fine without 2800 this feature. 2801 2802config APM_CPU_IDLE 2803 depends on CPU_IDLE 2804 bool "Make CPU Idle calls when idle" 2805 help 2806 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2807 On some machines, this can activate improved power savings, such as 2808 a slowed CPU clock rate, when the machine is idle. These idle calls 2809 are made after the idle loop has run for some length of time (e.g., 2810 333 mS). On some machines, this will cause a hang at boot time or 2811 whenever the CPU becomes idle. (On machines with more than one CPU, 2812 this option does nothing.) 2813 2814config APM_DISPLAY_BLANK 2815 bool "Enable console blanking using APM" 2816 help 2817 Enable console blanking using the APM. Some laptops can use this to 2818 turn off the LCD backlight when the screen blanker of the Linux 2819 virtual console blanks the screen. Note that this is only used by 2820 the virtual console screen blanker, and won't turn off the backlight 2821 when using the X Window system. This also doesn't have anything to 2822 do with your VESA-compliant power-saving monitor. Further, this 2823 option doesn't work for all laptops -- it might not turn off your 2824 backlight at all, or it might print a lot of errors to the console, 2825 especially if you are using gpm. 2826 2827config APM_ALLOW_INTS 2828 bool "Allow interrupts during APM BIOS calls" 2829 help 2830 Normally we disable external interrupts while we are making calls to 2831 the APM BIOS as a measure to lessen the effects of a badly behaving 2832 BIOS implementation. The BIOS should reenable interrupts if it 2833 needs to. Unfortunately, some BIOSes do not -- especially those in 2834 many of the newer IBM Thinkpads. If you experience hangs when you 2835 suspend, try setting this to Y. Otherwise, say N. 2836 2837endif # APM 2838 2839source "drivers/cpufreq/Kconfig" 2840 2841source "drivers/cpuidle/Kconfig" 2842 2843source "drivers/idle/Kconfig" 2844 2845endmenu 2846 2847menu "Bus options (PCI etc.)" 2848 2849choice 2850 prompt "PCI access mode" 2851 depends on X86_32 && PCI 2852 default PCI_GOANY 2853 help 2854 On PCI systems, the BIOS can be used to detect the PCI devices and 2855 determine their configuration. However, some old PCI motherboards 2856 have BIOS bugs and may crash if this is done. Also, some embedded 2857 PCI-based systems don't have any BIOS at all. Linux can also try to 2858 detect the PCI hardware directly without using the BIOS. 2859 2860 With this option, you can specify how Linux should detect the 2861 PCI devices. If you choose "BIOS", the BIOS will be used, 2862 if you choose "Direct", the BIOS won't be used, and if you 2863 choose "MMConfig", then PCI Express MMCONFIG will be used. 2864 If you choose "Any", the kernel will try MMCONFIG, then the 2865 direct access method and falls back to the BIOS if that doesn't 2866 work. If unsure, go with the default, which is "Any". 2867 2868config PCI_GOBIOS 2869 bool "BIOS" 2870 2871config PCI_GOMMCONFIG 2872 bool "MMConfig" 2873 2874config PCI_GODIRECT 2875 bool "Direct" 2876 2877config PCI_GOOLPC 2878 bool "OLPC XO-1" 2879 depends on OLPC 2880 2881config PCI_GOANY 2882 bool "Any" 2883 2884endchoice 2885 2886config PCI_BIOS 2887 def_bool y 2888 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2889 2890# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2891config PCI_DIRECT 2892 def_bool y 2893 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2894 2895config PCI_MMCONFIG 2896 bool "Support mmconfig PCI config space access" if X86_64 2897 default y 2898 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2899 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2900 help 2901 Add support for accessing the PCI configuration space as a memory 2902 mapped area. It is the recommended method if the system supports 2903 this (it must have PCI Express and ACPI for it to be available). 2904 2905 In the unlikely case that enabling this configuration option causes 2906 problems, the mechanism can be switched off with the 'pci=nommconf' 2907 command line parameter. 2908 2909 Say N only if you are sure that your platform does not support this 2910 access method or you have problems caused by it. 2911 2912 Say Y otherwise. 2913 2914config PCI_OLPC 2915 def_bool y 2916 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2917 2918config PCI_XEN 2919 def_bool y 2920 depends on PCI && XEN 2921 2922config MMCONF_FAM10H 2923 def_bool y 2924 depends on X86_64 && PCI_MMCONFIG && ACPI 2925 2926config PCI_CNB20LE_QUIRK 2927 bool "Read PCI host bridge windows from the CNB20LE chipset" if EXPERT 2928 depends on X86_32 && PCI 2929 help 2930 Read the PCI windows out of the CNB20LE host bridge. This allows 2931 PCI hotplug to work on systems with the CNB20LE chipset which do 2932 not have ACPI. 2933 2934 The ServerWorks (later Broadcom) CNB20LE was a chipset designed 2935 most probably only for Pentium III. 2936 2937 To find out if you have such a chipset, search for a PCI device with 2938 1166:0009 PCI IDs, for example by executing 2939 lspci -nn | grep '1166:0009' 2940 The code is inactive if there is none. 2941 2942 There's no public spec for this chipset, and this functionality 2943 is known to be incomplete. 2944 2945 You should say N unless you know you need this. 2946 2947config ISA_BUS 2948 bool "ISA bus support on modern systems" if EXPERT 2949 help 2950 Expose ISA bus device drivers and options available for selection and 2951 configuration. Enable this option if your target machine has an ISA 2952 bus. ISA is an older system, displaced by PCI and newer bus 2953 architectures -- if your target machine is modern, it probably does 2954 not have an ISA bus. 2955 2956 If unsure, say N. 2957 2958# x86_64 have no ISA slots, but can have ISA-style DMA. 2959config ISA_DMA_API 2960 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2961 default y 2962 help 2963 Enables ISA-style DMA support for devices requiring such controllers. 2964 If unsure, say Y. 2965 2966if X86_32 2967 2968config ISA 2969 bool "ISA support" 2970 help 2971 Find out whether you have ISA slots on your motherboard. ISA is the 2972 name of a bus system, i.e. the way the CPU talks to the other stuff 2973 inside your box. Other bus systems are PCI, EISA, MicroChannel 2974 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2975 newer boards don't support it. If you have ISA, say Y, otherwise N. 2976 2977config SCx200 2978 tristate "NatSemi SCx200 support" 2979 help 2980 This provides basic support for National Semiconductor's 2981 (now AMD's) Geode processors. The driver probes for the 2982 PCI-IDs of several on-chip devices, so its a good dependency 2983 for other scx200_* drivers. 2984 2985 If compiled as a module, the driver is named scx200. 2986 2987config SCx200HR_TIMER 2988 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2989 depends on SCx200 2990 default y 2991 help 2992 This driver provides a clocksource built upon the on-chip 2993 27MHz high-resolution timer. Its also a workaround for 2994 NSC Geode SC-1100's buggy TSC, which loses time when the 2995 processor goes idle (as is done by the scheduler). The 2996 other workaround is idle=poll boot option. 2997 2998config OLPC 2999 bool "One Laptop Per Child support" 3000 depends on !X86_PAE 3001 select GPIOLIB 3002 select OF 3003 select OF_PROMTREE 3004 select IRQ_DOMAIN 3005 select OLPC_EC 3006 help 3007 Add support for detecting the unique features of the OLPC 3008 XO hardware. 3009 3010config OLPC_XO1_PM 3011 bool "OLPC XO-1 Power Management" 3012 depends on OLPC && MFD_CS5535=y && PM_SLEEP 3013 help 3014 Add support for poweroff and suspend of the OLPC XO-1 laptop. 3015 3016config OLPC_XO1_RTC 3017 bool "OLPC XO-1 Real Time Clock" 3018 depends on OLPC_XO1_PM && RTC_DRV_CMOS 3019 help 3020 Add support for the XO-1 real time clock, which can be used as a 3021 programmable wakeup source. 3022 3023config OLPC_XO1_SCI 3024 bool "OLPC XO-1 SCI extras" 3025 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 3026 depends on INPUT=y 3027 select POWER_SUPPLY 3028 help 3029 Add support for SCI-based features of the OLPC XO-1 laptop: 3030 - EC-driven system wakeups 3031 - Power button 3032 - Ebook switch 3033 - Lid switch 3034 - AC adapter status updates 3035 - Battery status updates 3036 3037config OLPC_XO15_SCI 3038 bool "OLPC XO-1.5 SCI extras" 3039 depends on OLPC && ACPI 3040 select POWER_SUPPLY 3041 help 3042 Add support for SCI-based features of the OLPC XO-1.5 laptop: 3043 - EC-driven system wakeups 3044 - AC adapter status updates 3045 - Battery status updates 3046 3047config GEODE_COMMON 3048 bool 3049 3050config ALIX 3051 bool "PCEngines ALIX System Support (LED setup)" 3052 select GPIOLIB 3053 select GEODE_COMMON 3054 help 3055 This option enables system support for the PCEngines ALIX. 3056 At present this just sets up LEDs for GPIO control on 3057 ALIX2/3/6 boards. However, other system specific setup should 3058 get added here. 3059 3060 Note: You must still enable the drivers for GPIO and LED support 3061 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 3062 3063 Note: You have to set alix.force=1 for boards with Award BIOS. 3064 3065config NET5501 3066 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3067 select GPIOLIB 3068 select GEODE_COMMON 3069 help 3070 This option enables system support for the Soekris Engineering net5501. 3071 3072config GEOS 3073 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3074 select GPIOLIB 3075 select GEODE_COMMON 3076 depends on DMI 3077 help 3078 This option enables system support for the Traverse Technologies GEOS. 3079 3080config TS5500 3081 bool "Technologic Systems TS-5500 platform support" 3082 depends on MELAN 3083 select CHECK_SIGNATURE 3084 select NEW_LEDS 3085 select LEDS_CLASS 3086 help 3087 This option enables system support for the Technologic Systems TS-5500. 3088 3089endif # X86_32 3090 3091config AMD_NB 3092 def_bool y 3093 depends on AMD_NODE 3094 3095config AMD_NODE 3096 def_bool y 3097 depends on CPU_SUP_AMD && PCI 3098 3099endmenu 3100 3101menu "Binary Emulations" 3102 3103config IA32_EMULATION 3104 bool "IA32 Emulation" 3105 depends on X86_64 3106 select ARCH_WANT_OLD_COMPAT_IPC 3107 select BINFMT_ELF 3108 select COMPAT_OLD_SIGACTION 3109 help 3110 Include code to run legacy 32-bit programs under a 3111 64-bit kernel. You should likely turn this on, unless you're 3112 100% sure that you don't have any 32-bit programs left. 3113 3114config IA32_EMULATION_DEFAULT_DISABLED 3115 bool "IA32 emulation disabled by default" 3116 default n 3117 depends on IA32_EMULATION 3118 help 3119 Make IA32 emulation disabled by default. This prevents loading 32-bit 3120 processes and access to 32-bit syscalls. If unsure, leave it to its 3121 default value. 3122 3123config X86_X32_ABI 3124 bool "x32 ABI for 64-bit mode" 3125 depends on X86_64 3126 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3127 # compressed debug sections to x86_x32 properly: 3128 # https://github.com/ClangBuiltLinux/linux/issues/514 3129 # https://github.com/ClangBuiltLinux/linux/issues/1141 3130 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3131 help 3132 Include code to run binaries for the x32 native 32-bit ABI 3133 for 64-bit processors. An x32 process gets access to the 3134 full 64-bit register file and wide data path while leaving 3135 pointers at 32 bits for smaller memory footprint. 3136 3137config COMPAT_32 3138 def_bool y 3139 depends on IA32_EMULATION || X86_32 3140 select HAVE_UID16 3141 select OLD_SIGSUSPEND3 3142 3143config COMPAT 3144 def_bool y 3145 depends on IA32_EMULATION || X86_X32_ABI 3146 3147config COMPAT_FOR_U64_ALIGNMENT 3148 def_bool y 3149 depends on COMPAT 3150 3151endmenu 3152 3153config HAVE_ATOMIC_IOMAP 3154 def_bool y 3155 depends on X86_32 3156 3157source "arch/x86/kvm/Kconfig" 3158 3159source "arch/x86/Kconfig.cpufeatures" 3160 3161source "arch/x86/Kconfig.assembler" 3162