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_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE 32 select HAVE_ARCH_SOFT_DIRTY 33 select MODULES_USE_ELF_RELA 34 select NEED_DMA_MAP_STATE 35 select SWIOTLB 36 select ARCH_HAS_ELFCORE_COMPAT 37 select ZONE_DMA32 38 select EXECMEM if DYNAMIC_FTRACE 39 40config FORCE_DYNAMIC_FTRACE 41 def_bool y 42 depends on X86_32 43 depends on FUNCTION_TRACER 44 select DYNAMIC_FTRACE 45 help 46 We keep the static function tracing (!DYNAMIC_FTRACE) around 47 in order to test the non static function tracing in the 48 generic code, as other architectures still use it. But we 49 only need to keep it around for x86_64. No need to keep it 50 for x86_32. For x86_32, force DYNAMIC_FTRACE. 51# 52# Arch settings 53# 54# ( Note that options that are marked 'if X86_64' could in principle be 55# ported to 32-bit as well. ) 56# 57config X86 58 def_bool y 59 # 60 # Note: keep this list sorted alphabetically 61 # 62 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 63 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 64 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 65 select ARCH_32BIT_OFF_T if X86_32 66 select ARCH_CLOCKSOURCE_INIT 67 select ARCH_CONFIGURES_CPU_MITIGATIONS 68 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 69 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 70 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 71 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 72 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 73 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 74 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 75 select ARCH_HAS_CACHE_LINE_SIZE 76 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 77 select ARCH_HAS_CPU_FINALIZE_INIT 78 select ARCH_HAS_CPU_PASID if IOMMU_SVA 79 select ARCH_HAS_CURRENT_STACK_POINTER 80 select ARCH_HAS_DEBUG_VIRTUAL 81 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 82 select ARCH_HAS_DEVMEM_IS_ALLOWED 83 select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN 84 select ARCH_HAS_EARLY_DEBUG if KGDB 85 select ARCH_HAS_ELF_RANDOMIZE 86 select ARCH_HAS_FAST_MULTIPLIER 87 select ARCH_HAS_FORTIFY_SOURCE 88 select ARCH_HAS_GCOV_PROFILE_ALL 89 select ARCH_HAS_KCOV if X86_64 90 select ARCH_HAS_KERNEL_FPU_SUPPORT 91 select ARCH_HAS_MEM_ENCRYPT 92 select ARCH_HAS_MEMBARRIER_SYNC_CORE 93 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 94 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 95 select ARCH_HAS_PMEM_API if X86_64 96 select ARCH_HAS_PTE_DEVMAP if X86_64 97 select ARCH_HAS_PTE_SPECIAL 98 select ARCH_HAS_HW_PTE_YOUNG 99 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 100 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 101 select ARCH_HAS_COPY_MC if X86_64 102 select ARCH_HAS_SET_MEMORY 103 select ARCH_HAS_SET_DIRECT_MAP 104 select ARCH_HAS_STRICT_KERNEL_RWX 105 select ARCH_HAS_STRICT_MODULE_RWX 106 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 107 select ARCH_HAS_SYSCALL_WRAPPER 108 select ARCH_HAS_UBSAN 109 select ARCH_HAS_DEBUG_WX 110 select ARCH_HAS_ZONE_DMA_SET if EXPERT 111 select ARCH_HAVE_NMI_SAFE_CMPXCHG 112 select ARCH_HAVE_EXTRA_ELF_NOTES 113 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 114 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 115 select ARCH_MIGHT_HAVE_PC_PARPORT 116 select ARCH_MIGHT_HAVE_PC_SERIO 117 select ARCH_STACKWALK 118 select ARCH_SUPPORTS_ACPI 119 select ARCH_SUPPORTS_ATOMIC_RMW 120 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 121 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 122 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 123 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 124 select ARCH_SUPPORTS_CFI_CLANG if X86_64 125 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 126 select ARCH_SUPPORTS_LTO_CLANG 127 select ARCH_SUPPORTS_LTO_CLANG_THIN 128 select ARCH_SUPPORTS_RT 129 select ARCH_SUPPORTS_AUTOFDO_CLANG 130 select ARCH_USE_BUILTIN_BSWAP 131 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64 132 select ARCH_USE_MEMTEST 133 select ARCH_USE_QUEUED_RWLOCKS 134 select ARCH_USE_QUEUED_SPINLOCKS 135 select ARCH_USE_SYM_ANNOTATIONS 136 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 137 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 138 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 139 select ARCH_WANTS_NO_INSTR 140 select ARCH_WANT_GENERAL_HUGETLB 141 select ARCH_WANT_HUGE_PMD_SHARE if X86_64 142 select ARCH_WANT_LD_ORPHAN_WARN 143 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 144 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 145 select ARCH_WANTS_THP_SWAP if X86_64 146 select ARCH_HAS_PARANOID_L1D_FLUSH 147 select BUILDTIME_TABLE_SORT 148 select CLKEVT_I8253 149 select CLOCKSOURCE_WATCHDOG 150 # Word-size accesses may read uninitialized data past the trailing \0 151 # in strings and cause false KMSAN reports. 152 select DCACHE_WORD_ACCESS if !KMSAN 153 select DYNAMIC_SIGFRAME 154 select EDAC_ATOMIC_SCRUB 155 select EDAC_SUPPORT 156 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 157 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 158 select GENERIC_CLOCKEVENTS_MIN_ADJUST 159 select GENERIC_CMOS_UPDATE 160 select GENERIC_CPU_AUTOPROBE 161 select GENERIC_CPU_DEVICES 162 select GENERIC_CPU_VULNERABILITIES 163 select GENERIC_EARLY_IOREMAP 164 select GENERIC_ENTRY 165 select GENERIC_IOMAP 166 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 167 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 168 select GENERIC_IRQ_MIGRATION if SMP 169 select GENERIC_IRQ_PROBE 170 select GENERIC_IRQ_RESERVATION_MODE 171 select GENERIC_IRQ_SHOW 172 select GENERIC_PENDING_IRQ if SMP 173 select GENERIC_PTDUMP 174 select GENERIC_SMP_IDLE_THREAD 175 select GENERIC_TIME_VSYSCALL 176 select GENERIC_GETTIMEOFDAY 177 select GENERIC_VDSO_TIME_NS 178 select GENERIC_VDSO_OVERFLOW_PROTECT 179 select GUP_GET_PXX_LOW_HIGH if X86_PAE 180 select HARDIRQS_SW_RESEND 181 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 182 select HAS_IOPORT 183 select HAVE_ACPI_APEI if ACPI 184 select HAVE_ACPI_APEI_NMI if ACPI 185 select HAVE_ALIGNED_STRUCT_PAGE 186 select HAVE_ARCH_AUDITSYSCALL 187 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 188 select HAVE_ARCH_HUGE_VMALLOC if X86_64 189 select HAVE_ARCH_JUMP_LABEL 190 select HAVE_ARCH_JUMP_LABEL_RELATIVE 191 select HAVE_ARCH_KASAN if X86_64 192 select HAVE_ARCH_KASAN_VMALLOC if X86_64 193 select HAVE_ARCH_KFENCE 194 select HAVE_ARCH_KMSAN if X86_64 195 select HAVE_ARCH_KGDB 196 select HAVE_ARCH_MMAP_RND_BITS if MMU 197 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 198 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 199 select HAVE_ARCH_PREL32_RELOCATIONS 200 select HAVE_ARCH_SECCOMP_FILTER 201 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 202 select HAVE_ARCH_STACKLEAK 203 select HAVE_ARCH_TRACEHOOK 204 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 205 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 206 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 207 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 208 select HAVE_ARCH_VMAP_STACK if X86_64 209 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 210 select HAVE_ARCH_WITHIN_STACK_FRAMES 211 select HAVE_ASM_MODVERSIONS 212 select HAVE_CMPXCHG_DOUBLE 213 select HAVE_CMPXCHG_LOCAL 214 select HAVE_CONTEXT_TRACKING_USER if X86_64 215 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 216 select HAVE_C_RECORDMCOUNT 217 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 218 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 219 select HAVE_BUILDTIME_MCOUNT_SORT 220 select HAVE_DEBUG_KMEMLEAK 221 select HAVE_DMA_CONTIGUOUS 222 select HAVE_DYNAMIC_FTRACE 223 select HAVE_DYNAMIC_FTRACE_WITH_REGS 224 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 225 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 226 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 227 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 228 select HAVE_EBPF_JIT 229 select HAVE_EFFICIENT_UNALIGNED_ACCESS 230 select HAVE_EISA if X86_32 231 select HAVE_EXIT_THREAD 232 select HAVE_GUP_FAST 233 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 234 select HAVE_FTRACE_MCOUNT_RECORD 235 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 236 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 237 select HAVE_FUNCTION_TRACER 238 select HAVE_GCC_PLUGINS 239 select HAVE_HW_BREAKPOINT 240 select HAVE_IOREMAP_PROT 241 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 242 select HAVE_IRQ_TIME_ACCOUNTING 243 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 244 select HAVE_KERNEL_BZIP2 245 select HAVE_KERNEL_GZIP 246 select HAVE_KERNEL_LZ4 247 select HAVE_KERNEL_LZMA 248 select HAVE_KERNEL_LZO 249 select HAVE_KERNEL_XZ 250 select HAVE_KERNEL_ZSTD 251 select HAVE_KPROBES 252 select HAVE_KPROBES_ON_FTRACE 253 select HAVE_FUNCTION_ERROR_INJECTION 254 select HAVE_KRETPROBES 255 select HAVE_RETHOOK 256 select HAVE_LIVEPATCH if X86_64 257 select HAVE_MIXED_BREAKPOINTS_REGS 258 select HAVE_MOD_ARCH_SPECIFIC 259 select HAVE_MOVE_PMD 260 select HAVE_MOVE_PUD 261 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 262 select HAVE_NMI 263 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 264 select HAVE_OBJTOOL if X86_64 265 select HAVE_OPTPROBES 266 select HAVE_PAGE_SIZE_4KB 267 select HAVE_PCSPKR_PLATFORM 268 select HAVE_PERF_EVENTS 269 select HAVE_PERF_EVENTS_NMI 270 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 271 select HAVE_PCI 272 select HAVE_PERF_REGS 273 select HAVE_PERF_USER_STACK_DUMP 274 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 275 select MMU_GATHER_MERGE_VMAS 276 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 277 select HAVE_REGS_AND_STACK_ACCESS_API 278 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 279 select HAVE_FUNCTION_ARG_ACCESS_API 280 select HAVE_SETUP_PER_CPU_AREA 281 select HAVE_SOFTIRQ_ON_OWN_STACK 282 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 283 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 284 select HAVE_STATIC_CALL 285 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 286 select HAVE_PREEMPT_DYNAMIC_CALL 287 select HAVE_RSEQ 288 select HAVE_RUST if X86_64 289 select HAVE_SYSCALL_TRACEPOINTS 290 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 291 select HAVE_UNSTABLE_SCHED_CLOCK 292 select HAVE_USER_RETURN_NOTIFIER 293 select HAVE_GENERIC_VDSO 294 select VDSO_GETRANDOM if X86_64 295 select HOTPLUG_PARALLEL if SMP && X86_64 296 select HOTPLUG_SMT if SMP 297 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 298 select IRQ_FORCED_THREADING 299 select LOCK_MM_AND_FIND_VMA 300 select NEED_PER_CPU_EMBED_FIRST_CHUNK 301 select NEED_PER_CPU_PAGE_FIRST_CHUNK 302 select NEED_SG_DMA_LENGTH 303 select NUMA_MEMBLKS if NUMA 304 select PCI_DOMAINS if PCI 305 select PCI_LOCKLESS_CONFIG if PCI 306 select PERF_EVENTS 307 select RTC_LIB 308 select RTC_MC146818_LIB 309 select SPARSE_IRQ 310 select SYSCTL_EXCEPTION_TRACE 311 select THREAD_INFO_IN_TASK 312 select TRACE_IRQFLAGS_SUPPORT 313 select TRACE_IRQFLAGS_NMI_SUPPORT 314 select USER_STACKTRACE_SUPPORT 315 select HAVE_ARCH_KCSAN if X86_64 316 select PROC_PID_ARCH_STATUS if PROC_FS 317 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 318 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 319 select FUNCTION_ALIGNMENT_4B 320 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 321 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 322 323config INSTRUCTION_DECODER 324 def_bool y 325 depends on KPROBES || PERF_EVENTS || UPROBES 326 327config OUTPUT_FORMAT 328 string 329 default "elf32-i386" if X86_32 330 default "elf64-x86-64" if X86_64 331 332config LOCKDEP_SUPPORT 333 def_bool y 334 335config STACKTRACE_SUPPORT 336 def_bool y 337 338config MMU 339 def_bool y 340 341config ARCH_MMAP_RND_BITS_MIN 342 default 28 if 64BIT 343 default 8 344 345config ARCH_MMAP_RND_BITS_MAX 346 default 32 if 64BIT 347 default 16 348 349config ARCH_MMAP_RND_COMPAT_BITS_MIN 350 default 8 351 352config ARCH_MMAP_RND_COMPAT_BITS_MAX 353 default 16 354 355config SBUS 356 bool 357 358config GENERIC_ISA_DMA 359 def_bool y 360 depends on ISA_DMA_API 361 362config GENERIC_CSUM 363 bool 364 default y if KMSAN || KASAN 365 366config GENERIC_BUG 367 def_bool y 368 depends on BUG 369 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 370 371config GENERIC_BUG_RELATIVE_POINTERS 372 bool 373 374config ARCH_MAY_HAVE_PC_FDC 375 def_bool y 376 depends on ISA_DMA_API 377 378config GENERIC_CALIBRATE_DELAY 379 def_bool y 380 381config ARCH_HAS_CPU_RELAX 382 def_bool y 383 384config ARCH_HIBERNATION_POSSIBLE 385 def_bool y 386 387config ARCH_SUSPEND_POSSIBLE 388 def_bool y 389 390config AUDIT_ARCH 391 def_bool y if X86_64 392 393config KASAN_SHADOW_OFFSET 394 hex 395 depends on KASAN 396 default 0xdffffc0000000000 397 398config HAVE_INTEL_TXT 399 def_bool y 400 depends on INTEL_IOMMU && ACPI 401 402config X86_64_SMP 403 def_bool y 404 depends on X86_64 && SMP 405 406config ARCH_SUPPORTS_UPROBES 407 def_bool y 408 409config FIX_EARLYCON_MEM 410 def_bool y 411 412config DYNAMIC_PHYSICAL_MASK 413 bool 414 415config PGTABLE_LEVELS 416 int 417 default 5 if X86_5LEVEL 418 default 4 if X86_64 419 default 3 if X86_PAE 420 default 2 421 422config CC_HAS_SANE_STACKPROTECTOR 423 bool 424 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 425 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 426 help 427 We have to make sure stack protector is unconditionally disabled if 428 the compiler produces broken code or if it does not let us control 429 the segment on 32-bit kernels. 430 431menu "Processor type and features" 432 433config SMP 434 bool "Symmetric multi-processing support" 435 help 436 This enables support for systems with more than one CPU. If you have 437 a system with only one CPU, say N. If you have a system with more 438 than one CPU, say Y. 439 440 If you say N here, the kernel will run on uni- and multiprocessor 441 machines, but will use only one CPU of a multiprocessor machine. If 442 you say Y here, the kernel will run on many, but not all, 443 uniprocessor machines. On a uniprocessor machine, the kernel 444 will run faster if you say N here. 445 446 Note that if you say Y here and choose architecture "586" or 447 "Pentium" under "Processor family", the kernel will not work on 486 448 architectures. Similarly, multiprocessor kernels for the "PPro" 449 architecture may not work on all Pentium based boards. 450 451 People using multiprocessor machines who say Y here should also say 452 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 453 Management" code will be disabled if you say Y here. 454 455 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 456 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 457 <http://www.tldp.org/docs.html#howto>. 458 459 If you don't know what to do here, say N. 460 461config X86_X2APIC 462 bool "Support x2apic" 463 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 464 help 465 This enables x2apic support on CPUs that have this feature. 466 467 This allows 32-bit apic IDs (so it can support very large systems), 468 and accesses the local apic via MSRs not via mmio. 469 470 Some Intel systems circa 2022 and later are locked into x2APIC mode 471 and can not fall back to the legacy APIC modes if SGX or TDX are 472 enabled in the BIOS. They will boot with very reduced functionality 473 without enabling this option. 474 475 If you don't know what to do here, say N. 476 477config X86_POSTED_MSI 478 bool "Enable MSI and MSI-x delivery by posted interrupts" 479 depends on X86_64 && IRQ_REMAP 480 help 481 This enables MSIs that are under interrupt remapping to be delivered as 482 posted interrupts to the host kernel. Interrupt throughput can 483 potentially be improved by coalescing CPU notifications during high 484 frequency bursts. 485 486 If you don't know what to do here, say N. 487 488config X86_MPPARSE 489 bool "Enable MPS table" if ACPI 490 default y 491 depends on X86_LOCAL_APIC 492 help 493 For old smp systems that do not have proper acpi support. Newer systems 494 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 495 496config X86_CPU_RESCTRL 497 bool "x86 CPU resource control support" 498 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 499 select KERNFS 500 select PROC_CPU_RESCTRL if PROC_FS 501 help 502 Enable x86 CPU resource control support. 503 504 Provide support for the allocation and monitoring of system resources 505 usage by the CPU. 506 507 Intel calls this Intel Resource Director Technology 508 (Intel(R) RDT). More information about RDT can be found in the 509 Intel x86 Architecture Software Developer Manual. 510 511 AMD calls this AMD Platform Quality of Service (AMD QoS). 512 More information about AMD QoS can be found in the AMD64 Technology 513 Platform Quality of Service Extensions manual. 514 515 Say N if unsure. 516 517config X86_FRED 518 bool "Flexible Return and Event Delivery" 519 depends on X86_64 520 help 521 When enabled, try to use Flexible Return and Event Delivery 522 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 523 ring transitions and exception/interrupt handling if the 524 system supports it. 525 526config X86_BIGSMP 527 bool "Support for big SMP systems with more than 8 CPUs" 528 depends on SMP && X86_32 529 help 530 This option is needed for the systems that have more than 8 CPUs. 531 532config X86_EXTENDED_PLATFORM 533 bool "Support for extended (non-PC) x86 platforms" 534 default y 535 help 536 If you disable this option then the kernel will only support 537 standard PC platforms. (which covers the vast majority of 538 systems out there.) 539 540 If you enable this option then you'll be able to select support 541 for the following non-PC x86 platforms, depending on the value of 542 CONFIG_64BIT. 543 544 32-bit platforms (CONFIG_64BIT=n): 545 Goldfish (Android emulator) 546 AMD Elan 547 RDC R-321x SoC 548 SGI 320/540 (Visual Workstation) 549 STA2X11-based (e.g. Northville) 550 Moorestown MID devices 551 552 64-bit platforms (CONFIG_64BIT=y): 553 Numascale NumaChip 554 ScaleMP vSMP 555 SGI Ultraviolet 556 557 If you have one of these systems, or if you want to build a 558 generic distribution kernel, say Y here - otherwise say N. 559 560# This is an alphabetically sorted list of 64 bit extended platforms 561# Please maintain the alphabetic order if and when there are additions 562config X86_NUMACHIP 563 bool "Numascale NumaChip" 564 depends on X86_64 565 depends on X86_EXTENDED_PLATFORM 566 depends on NUMA 567 depends on SMP 568 depends on X86_X2APIC 569 depends on PCI_MMCONFIG 570 help 571 Adds support for Numascale NumaChip large-SMP systems. Needed to 572 enable more than ~168 cores. 573 If you don't have one of these, you should say N here. 574 575config X86_VSMP 576 bool "ScaleMP vSMP" 577 select HYPERVISOR_GUEST 578 select PARAVIRT 579 depends on X86_64 && PCI 580 depends on X86_EXTENDED_PLATFORM 581 depends on SMP 582 help 583 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 584 supposed to run on these EM64T-based machines. Only choose this option 585 if you have one of these machines. 586 587config X86_UV 588 bool "SGI Ultraviolet" 589 depends on X86_64 590 depends on X86_EXTENDED_PLATFORM 591 depends on NUMA 592 depends on EFI 593 depends on KEXEC_CORE 594 depends on X86_X2APIC 595 depends on PCI 596 help 597 This option is needed in order to support SGI Ultraviolet systems. 598 If you don't have one of these, you should say N here. 599 600# Following is an alphabetically sorted list of 32 bit extended platforms 601# Please maintain the alphabetic order if and when there are additions 602 603config X86_GOLDFISH 604 bool "Goldfish (Virtual Platform)" 605 depends on X86_EXTENDED_PLATFORM 606 help 607 Enable support for the Goldfish virtual platform used primarily 608 for Android development. Unless you are building for the Android 609 Goldfish emulator say N here. 610 611config X86_INTEL_CE 612 bool "CE4100 TV platform" 613 depends on PCI 614 depends on PCI_GODIRECT 615 depends on X86_IO_APIC 616 depends on X86_32 617 depends on X86_EXTENDED_PLATFORM 618 select X86_REBOOTFIXUPS 619 select OF 620 select OF_EARLY_FLATTREE 621 help 622 Select for the Intel CE media processor (CE4100) SOC. 623 This option compiles in support for the CE4100 SOC for settop 624 boxes and media devices. 625 626config X86_INTEL_MID 627 bool "Intel MID platform support" 628 depends on X86_EXTENDED_PLATFORM 629 depends on X86_PLATFORM_DEVICES 630 depends on PCI 631 depends on X86_64 || (PCI_GOANY && X86_32) 632 depends on X86_IO_APIC 633 select I2C 634 select DW_APB_TIMER 635 select INTEL_SCU_PCI 636 help 637 Select to build a kernel capable of supporting Intel MID (Mobile 638 Internet Device) platform systems which do not have the PCI legacy 639 interfaces. If you are building for a PC class system say N here. 640 641 Intel MID platforms are based on an Intel processor and chipset which 642 consume less power than most of the x86 derivatives. 643 644config X86_INTEL_QUARK 645 bool "Intel Quark platform support" 646 depends on X86_32 647 depends on X86_EXTENDED_PLATFORM 648 depends on X86_PLATFORM_DEVICES 649 depends on X86_TSC 650 depends on PCI 651 depends on PCI_GOANY 652 depends on X86_IO_APIC 653 select IOSF_MBI 654 select INTEL_IMR 655 select COMMON_CLK 656 help 657 Select to include support for Quark X1000 SoC. 658 Say Y here if you have a Quark based system such as the Arduino 659 compatible Intel Galileo. 660 661config X86_INTEL_LPSS 662 bool "Intel Low Power Subsystem Support" 663 depends on X86 && ACPI && PCI 664 select COMMON_CLK 665 select PINCTRL 666 select IOSF_MBI 667 help 668 Select to build support for Intel Low Power Subsystem such as 669 found on Intel Lynxpoint PCH. Selecting this option enables 670 things like clock tree (common clock framework) and pincontrol 671 which are needed by the LPSS peripheral drivers. 672 673config X86_AMD_PLATFORM_DEVICE 674 bool "AMD ACPI2Platform devices support" 675 depends on ACPI 676 select COMMON_CLK 677 select PINCTRL 678 help 679 Select to interpret AMD specific ACPI device to platform device 680 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 681 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 682 implemented under PINCTRL subsystem. 683 684config IOSF_MBI 685 tristate "Intel SoC IOSF Sideband support for SoC platforms" 686 depends on PCI 687 help 688 This option enables sideband register access support for Intel SoC 689 platforms. On these platforms the IOSF sideband is used in lieu of 690 MSR's for some register accesses, mostly but not limited to thermal 691 and power. Drivers may query the availability of this device to 692 determine if they need the sideband in order to work on these 693 platforms. The sideband is available on the following SoC products. 694 This list is not meant to be exclusive. 695 - BayTrail 696 - Braswell 697 - Quark 698 699 You should say Y if you are running a kernel on one of these SoC's. 700 701config IOSF_MBI_DEBUG 702 bool "Enable IOSF sideband access through debugfs" 703 depends on IOSF_MBI && DEBUG_FS 704 help 705 Select this option to expose the IOSF sideband access registers (MCR, 706 MDR, MCRX) through debugfs to write and read register information from 707 different units on the SoC. This is most useful for obtaining device 708 state information for debug and analysis. As this is a general access 709 mechanism, users of this option would have specific knowledge of the 710 device they want to access. 711 712 If you don't require the option or are in doubt, say N. 713 714config X86_RDC321X 715 bool "RDC R-321x SoC" 716 depends on X86_32 717 depends on X86_EXTENDED_PLATFORM 718 select M486 719 select X86_REBOOTFIXUPS 720 help 721 This option is needed for RDC R-321x system-on-chip, also known 722 as R-8610-(G). 723 If you don't have one of these chips, you should say N here. 724 725config X86_32_NON_STANDARD 726 bool "Support non-standard 32-bit SMP architectures" 727 depends on X86_32 && SMP 728 depends on X86_EXTENDED_PLATFORM 729 help 730 This option compiles in the bigsmp and STA2X11 default 731 subarchitectures. It is intended for a generic binary 732 kernel. If you select them all, kernel will probe it one by 733 one and will fallback to default. 734 735# Alphabetically sorted list of Non standard 32 bit platforms 736 737config X86_SUPPORTS_MEMORY_FAILURE 738 def_bool y 739 # MCE code calls memory_failure(): 740 depends on X86_MCE 741 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 742 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 743 depends on X86_64 || !SPARSEMEM 744 select ARCH_SUPPORTS_MEMORY_FAILURE 745 746config STA2X11 747 bool "STA2X11 Companion Chip Support" 748 depends on X86_32_NON_STANDARD && PCI 749 select SWIOTLB 750 select MFD_STA2X11 751 select GPIOLIB 752 help 753 This adds support for boards based on the STA2X11 IO-Hub, 754 a.k.a. "ConneXt". The chip is used in place of the standard 755 PC chipset, so all "standard" peripherals are missing. If this 756 option is selected the kernel will still be able to boot on 757 standard PC machines. 758 759config X86_32_IRIS 760 tristate "Eurobraille/Iris poweroff module" 761 depends on X86_32 762 help 763 The Iris machines from EuroBraille do not have APM or ACPI support 764 to shut themselves down properly. A special I/O sequence is 765 needed to do so, which is what this module does at 766 kernel shutdown. 767 768 This is only for Iris machines from EuroBraille. 769 770 If unused, say N. 771 772config SCHED_OMIT_FRAME_POINTER 773 def_bool y 774 prompt "Single-depth WCHAN output" 775 depends on X86 776 help 777 Calculate simpler /proc/<PID>/wchan values. If this option 778 is disabled then wchan values will recurse back to the 779 caller function. This provides more accurate wchan values, 780 at the expense of slightly more scheduling overhead. 781 782 If in doubt, say "Y". 783 784menuconfig HYPERVISOR_GUEST 785 bool "Linux guest support" 786 help 787 Say Y here to enable options for running Linux under various hyper- 788 visors. This option enables basic hypervisor detection and platform 789 setup. 790 791 If you say N, all options in this submenu will be skipped and 792 disabled, and Linux guest support won't be built in. 793 794if HYPERVISOR_GUEST 795 796config PARAVIRT 797 bool "Enable paravirtualization code" 798 depends on HAVE_STATIC_CALL 799 help 800 This changes the kernel so it can modify itself when it is run 801 under a hypervisor, potentially improving performance significantly 802 over full virtualization. However, when run without a hypervisor 803 the kernel is theoretically slower and slightly larger. 804 805config PARAVIRT_XXL 806 bool 807 808config PARAVIRT_DEBUG 809 bool "paravirt-ops debugging" 810 depends on PARAVIRT && DEBUG_KERNEL 811 help 812 Enable to debug paravirt_ops internals. Specifically, BUG if 813 a paravirt_op is missing when it is called. 814 815config PARAVIRT_SPINLOCKS 816 bool "Paravirtualization layer for spinlocks" 817 depends on PARAVIRT && SMP 818 help 819 Paravirtualized spinlocks allow a pvops backend to replace the 820 spinlock implementation with something virtualization-friendly 821 (for example, block the virtual CPU rather than spinning). 822 823 It has a minimal impact on native kernels and gives a nice performance 824 benefit on paravirtualized KVM / Xen kernels. 825 826 If you are unsure how to answer this question, answer Y. 827 828config X86_HV_CALLBACK_VECTOR 829 def_bool n 830 831source "arch/x86/xen/Kconfig" 832 833config KVM_GUEST 834 bool "KVM Guest support (including kvmclock)" 835 depends on PARAVIRT 836 select PARAVIRT_CLOCK 837 select ARCH_CPUIDLE_HALTPOLL 838 select X86_HV_CALLBACK_VECTOR 839 default y 840 help 841 This option enables various optimizations for running under the KVM 842 hypervisor. It includes a paravirtualized clock, so that instead 843 of relying on a PIT (or probably other) emulation by the 844 underlying device model, the host provides the guest with 845 timing infrastructure such as time of day, and system time 846 847config ARCH_CPUIDLE_HALTPOLL 848 def_bool n 849 prompt "Disable host haltpoll when loading haltpoll driver" 850 help 851 If virtualized under KVM, disable host haltpoll. 852 853config PVH 854 bool "Support for running PVH guests" 855 help 856 This option enables the PVH entry point for guest virtual machines 857 as specified in the x86/HVM direct boot ABI. 858 859config PARAVIRT_TIME_ACCOUNTING 860 bool "Paravirtual steal time accounting" 861 depends on PARAVIRT 862 help 863 Select this option to enable fine granularity task steal time 864 accounting. Time spent executing other tasks in parallel with 865 the current vCPU is discounted from the vCPU power. To account for 866 that, there can be a small performance impact. 867 868 If in doubt, say N here. 869 870config PARAVIRT_CLOCK 871 bool 872 873config JAILHOUSE_GUEST 874 bool "Jailhouse non-root cell support" 875 depends on X86_64 && PCI 876 select X86_PM_TIMER 877 help 878 This option allows to run Linux as guest in a Jailhouse non-root 879 cell. You can leave this option disabled if you only want to start 880 Jailhouse and run Linux afterwards in the root cell. 881 882config ACRN_GUEST 883 bool "ACRN Guest support" 884 depends on X86_64 885 select X86_HV_CALLBACK_VECTOR 886 help 887 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 888 a flexible, lightweight reference open-source hypervisor, built with 889 real-time and safety-criticality in mind. It is built for embedded 890 IOT with small footprint and real-time features. More details can be 891 found in https://projectacrn.org/. 892 893config INTEL_TDX_GUEST 894 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 895 depends on X86_64 && CPU_SUP_INTEL 896 depends on X86_X2APIC 897 depends on EFI_STUB 898 depends on PARAVIRT 899 select ARCH_HAS_CC_PLATFORM 900 select X86_MEM_ENCRYPT 901 select X86_MCE 902 select UNACCEPTED_MEMORY 903 help 904 Support running as a guest under Intel TDX. Without this support, 905 the guest kernel can not boot or run under TDX. 906 TDX includes memory encryption and integrity capabilities 907 which protect the confidentiality and integrity of guest 908 memory contents and CPU state. TDX guests are protected from 909 some attacks from the VMM. 910 911endif # HYPERVISOR_GUEST 912 913source "arch/x86/Kconfig.cpu" 914 915config HPET_TIMER 916 def_bool X86_64 917 prompt "HPET Timer Support" if X86_32 918 help 919 Use the IA-PC HPET (High Precision Event Timer) to manage 920 time in preference to the PIT and RTC, if a HPET is 921 present. 922 HPET is the next generation timer replacing legacy 8254s. 923 The HPET provides a stable time base on SMP 924 systems, unlike the TSC, but it is more expensive to access, 925 as it is off-chip. The interface used is documented 926 in the HPET spec, revision 1. 927 928 You can safely choose Y here. However, HPET will only be 929 activated if the platform and the BIOS support this feature. 930 Otherwise the 8254 will be used for timing services. 931 932 Choose N to continue using the legacy 8254 timer. 933 934config HPET_EMULATE_RTC 935 def_bool y 936 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 937 938# Mark as expert because too many people got it wrong. 939# The code disables itself when not needed. 940config DMI 941 default y 942 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 943 bool "Enable DMI scanning" if EXPERT 944 help 945 Enabled scanning of DMI to identify machine quirks. Say Y 946 here unless you have verified that your setup is not 947 affected by entries in the DMI blacklist. Required by PNP 948 BIOS code. 949 950config GART_IOMMU 951 bool "Old AMD GART IOMMU support" 952 select IOMMU_HELPER 953 select SWIOTLB 954 depends on X86_64 && PCI && AMD_NB 955 help 956 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 957 GART based hardware IOMMUs. 958 959 The GART supports full DMA access for devices with 32-bit access 960 limitations, on systems with more than 3 GB. This is usually needed 961 for USB, sound, many IDE/SATA chipsets and some other devices. 962 963 Newer systems typically have a modern AMD IOMMU, supported via 964 the CONFIG_AMD_IOMMU=y config option. 965 966 In normal configurations this driver is only active when needed: 967 there's more than 3 GB of memory and the system contains a 968 32-bit limited device. 969 970 If unsure, say Y. 971 972config BOOT_VESA_SUPPORT 973 bool 974 help 975 If true, at least one selected framebuffer driver can take advantage 976 of VESA video modes set at an early boot stage via the vga= parameter. 977 978config MAXSMP 979 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 980 depends on X86_64 && SMP && DEBUG_KERNEL 981 select CPUMASK_OFFSTACK 982 help 983 Enable maximum number of CPUS and NUMA Nodes for this architecture. 984 If unsure, say N. 985 986# 987# The maximum number of CPUs supported: 988# 989# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 990# and which can be configured interactively in the 991# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 992# 993# The ranges are different on 32-bit and 64-bit kernels, depending on 994# hardware capabilities and scalability features of the kernel. 995# 996# ( If MAXSMP is enabled we just use the highest possible value and disable 997# interactive configuration. ) 998# 999 1000config NR_CPUS_RANGE_BEGIN 1001 int 1002 default NR_CPUS_RANGE_END if MAXSMP 1003 default 1 if !SMP 1004 default 2 1005 1006config NR_CPUS_RANGE_END 1007 int 1008 depends on X86_32 1009 default 64 if SMP && X86_BIGSMP 1010 default 8 if SMP && !X86_BIGSMP 1011 default 1 if !SMP 1012 1013config NR_CPUS_RANGE_END 1014 int 1015 depends on X86_64 1016 default 8192 if SMP && CPUMASK_OFFSTACK 1017 default 512 if SMP && !CPUMASK_OFFSTACK 1018 default 1 if !SMP 1019 1020config NR_CPUS_DEFAULT 1021 int 1022 depends on X86_32 1023 default 32 if X86_BIGSMP 1024 default 8 if SMP 1025 default 1 if !SMP 1026 1027config NR_CPUS_DEFAULT 1028 int 1029 depends on X86_64 1030 default 8192 if MAXSMP 1031 default 64 if SMP 1032 default 1 if !SMP 1033 1034config NR_CPUS 1035 int "Maximum number of CPUs" if SMP && !MAXSMP 1036 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1037 default NR_CPUS_DEFAULT 1038 help 1039 This allows you to specify the maximum number of CPUs which this 1040 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1041 supported value is 8192, otherwise the maximum value is 512. The 1042 minimum value which makes sense is 2. 1043 1044 This is purely to save memory: each supported CPU adds about 8KB 1045 to the kernel image. 1046 1047config SCHED_CLUSTER 1048 bool "Cluster scheduler support" 1049 depends on SMP 1050 default y 1051 help 1052 Cluster scheduler support improves the CPU scheduler's decision 1053 making when dealing with machines that have clusters of CPUs. 1054 Cluster usually means a couple of CPUs which are placed closely 1055 by sharing mid-level caches, last-level cache tags or internal 1056 busses. 1057 1058config SCHED_SMT 1059 def_bool y if SMP 1060 1061config SCHED_MC 1062 def_bool y 1063 prompt "Multi-core scheduler support" 1064 depends on SMP 1065 help 1066 Multi-core scheduler support improves the CPU scheduler's decision 1067 making when dealing with multi-core CPU chips at a cost of slightly 1068 increased overhead in some places. If unsure say N here. 1069 1070config SCHED_MC_PRIO 1071 bool "CPU core priorities scheduler support" 1072 depends on SCHED_MC 1073 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1074 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1075 select CPU_FREQ 1076 default y 1077 help 1078 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1079 core ordering determined at manufacturing time, which allows 1080 certain cores to reach higher turbo frequencies (when running 1081 single threaded workloads) than others. 1082 1083 Enabling this kernel feature teaches the scheduler about 1084 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1085 scheduler's CPU selection logic accordingly, so that higher 1086 overall system performance can be achieved. 1087 1088 This feature will have no effect on CPUs without this feature. 1089 1090 If unsure say Y here. 1091 1092config UP_LATE_INIT 1093 def_bool y 1094 depends on !SMP && X86_LOCAL_APIC 1095 1096config X86_UP_APIC 1097 bool "Local APIC support on uniprocessors" if !PCI_MSI 1098 default PCI_MSI 1099 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1100 help 1101 A local APIC (Advanced Programmable Interrupt Controller) is an 1102 integrated interrupt controller in the CPU. If you have a single-CPU 1103 system which has a processor with a local APIC, you can say Y here to 1104 enable and use it. If you say Y here even though your machine doesn't 1105 have a local APIC, then the kernel will still run with no slowdown at 1106 all. The local APIC supports CPU-generated self-interrupts (timer, 1107 performance counters), and the NMI watchdog which detects hard 1108 lockups. 1109 1110config X86_UP_IOAPIC 1111 bool "IO-APIC support on uniprocessors" 1112 depends on X86_UP_APIC 1113 help 1114 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1115 SMP-capable replacement for PC-style interrupt controllers. Most 1116 SMP systems and many recent uniprocessor systems have one. 1117 1118 If you have a single-CPU system with an IO-APIC, you can say Y here 1119 to use it. If you say Y here even though your machine doesn't have 1120 an IO-APIC, then the kernel will still run with no slowdown at all. 1121 1122config X86_LOCAL_APIC 1123 def_bool y 1124 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1125 select IRQ_DOMAIN_HIERARCHY 1126 1127config ACPI_MADT_WAKEUP 1128 def_bool y 1129 depends on X86_64 1130 depends on ACPI 1131 depends on SMP 1132 depends on X86_LOCAL_APIC 1133 1134config X86_IO_APIC 1135 def_bool y 1136 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1137 1138config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1139 bool "Reroute for broken boot IRQs" 1140 depends on X86_IO_APIC 1141 help 1142 This option enables a workaround that fixes a source of 1143 spurious interrupts. This is recommended when threaded 1144 interrupt handling is used on systems where the generation of 1145 superfluous "boot interrupts" cannot be disabled. 1146 1147 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1148 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1149 kernel does during interrupt handling). On chipsets where this 1150 boot IRQ generation cannot be disabled, this workaround keeps 1151 the original IRQ line masked so that only the equivalent "boot 1152 IRQ" is delivered to the CPUs. The workaround also tells the 1153 kernel to set up the IRQ handler on the boot IRQ line. In this 1154 way only one interrupt is delivered to the kernel. Otherwise 1155 the spurious second interrupt may cause the kernel to bring 1156 down (vital) interrupt lines. 1157 1158 Only affects "broken" chipsets. Interrupt sharing may be 1159 increased on these systems. 1160 1161config X86_MCE 1162 bool "Machine Check / overheating reporting" 1163 select GENERIC_ALLOCATOR 1164 default y 1165 help 1166 Machine Check support allows the processor to notify the 1167 kernel if it detects a problem (e.g. overheating, data corruption). 1168 The action the kernel takes depends on the severity of the problem, 1169 ranging from warning messages to halting the machine. 1170 1171config X86_MCELOG_LEGACY 1172 bool "Support for deprecated /dev/mcelog character device" 1173 depends on X86_MCE 1174 help 1175 Enable support for /dev/mcelog which is needed by the old mcelog 1176 userspace logging daemon. Consider switching to the new generation 1177 rasdaemon solution. 1178 1179config X86_MCE_INTEL 1180 def_bool y 1181 prompt "Intel MCE features" 1182 depends on X86_MCE && X86_LOCAL_APIC 1183 help 1184 Additional support for intel specific MCE features such as 1185 the thermal monitor. 1186 1187config X86_MCE_AMD 1188 def_bool y 1189 prompt "AMD MCE features" 1190 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1191 help 1192 Additional support for AMD specific MCE features such as 1193 the DRAM Error Threshold. 1194 1195config X86_ANCIENT_MCE 1196 bool "Support for old Pentium 5 / WinChip machine checks" 1197 depends on X86_32 && X86_MCE 1198 help 1199 Include support for machine check handling on old Pentium 5 or WinChip 1200 systems. These typically need to be enabled explicitly on the command 1201 line. 1202 1203config X86_MCE_THRESHOLD 1204 depends on X86_MCE_AMD || X86_MCE_INTEL 1205 def_bool y 1206 1207config X86_MCE_INJECT 1208 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1209 tristate "Machine check injector support" 1210 help 1211 Provide support for injecting machine checks for testing purposes. 1212 If you don't know what a machine check is and you don't do kernel 1213 QA it is safe to say n. 1214 1215source "arch/x86/events/Kconfig" 1216 1217config X86_LEGACY_VM86 1218 bool "Legacy VM86 support" 1219 depends on X86_32 1220 help 1221 This option allows user programs to put the CPU into V8086 1222 mode, which is an 80286-era approximation of 16-bit real mode. 1223 1224 Some very old versions of X and/or vbetool require this option 1225 for user mode setting. Similarly, DOSEMU will use it if 1226 available to accelerate real mode DOS programs. However, any 1227 recent version of DOSEMU, X, or vbetool should be fully 1228 functional even without kernel VM86 support, as they will all 1229 fall back to software emulation. Nevertheless, if you are using 1230 a 16-bit DOS program where 16-bit performance matters, vm86 1231 mode might be faster than emulation and you might want to 1232 enable this option. 1233 1234 Note that any app that works on a 64-bit kernel is unlikely to 1235 need this option, as 64-bit kernels don't, and can't, support 1236 V8086 mode. This option is also unrelated to 16-bit protected 1237 mode and is not needed to run most 16-bit programs under Wine. 1238 1239 Enabling this option increases the complexity of the kernel 1240 and slows down exception handling a tiny bit. 1241 1242 If unsure, say N here. 1243 1244config VM86 1245 bool 1246 default X86_LEGACY_VM86 1247 1248config X86_16BIT 1249 bool "Enable support for 16-bit segments" if EXPERT 1250 default y 1251 depends on MODIFY_LDT_SYSCALL 1252 help 1253 This option is required by programs like Wine to run 16-bit 1254 protected mode legacy code on x86 processors. Disabling 1255 this option saves about 300 bytes on i386, or around 6K text 1256 plus 16K runtime memory on x86-64, 1257 1258config X86_ESPFIX32 1259 def_bool y 1260 depends on X86_16BIT && X86_32 1261 1262config X86_ESPFIX64 1263 def_bool y 1264 depends on X86_16BIT && X86_64 1265 1266config X86_VSYSCALL_EMULATION 1267 bool "Enable vsyscall emulation" if EXPERT 1268 default y 1269 depends on X86_64 1270 help 1271 This enables emulation of the legacy vsyscall page. Disabling 1272 it is roughly equivalent to booting with vsyscall=none, except 1273 that it will also disable the helpful warning if a program 1274 tries to use a vsyscall. With this option set to N, offending 1275 programs will just segfault, citing addresses of the form 1276 0xffffffffff600?00. 1277 1278 This option is required by many programs built before 2013, and 1279 care should be used even with newer programs if set to N. 1280 1281 Disabling this option saves about 7K of kernel size and 1282 possibly 4K of additional runtime pagetable memory. 1283 1284config X86_IOPL_IOPERM 1285 bool "IOPERM and IOPL Emulation" 1286 default y 1287 help 1288 This enables the ioperm() and iopl() syscalls which are necessary 1289 for legacy applications. 1290 1291 Legacy IOPL support is an overbroad mechanism which allows user 1292 space aside of accessing all 65536 I/O ports also to disable 1293 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1294 capabilities and permission from potentially active security 1295 modules. 1296 1297 The emulation restricts the functionality of the syscall to 1298 only allowing the full range I/O port access, but prevents the 1299 ability to disable interrupts from user space which would be 1300 granted if the hardware IOPL mechanism would be used. 1301 1302config TOSHIBA 1303 tristate "Toshiba Laptop support" 1304 depends on X86_32 1305 help 1306 This adds a driver to safely access the System Management Mode of 1307 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1308 not work on models with a Phoenix BIOS. The System Management Mode 1309 is used to set the BIOS and power saving options on Toshiba portables. 1310 1311 For information on utilities to make use of this driver see the 1312 Toshiba Linux utilities web site at: 1313 <http://www.buzzard.org.uk/toshiba/>. 1314 1315 Say Y if you intend to run this kernel on a Toshiba portable. 1316 Say N otherwise. 1317 1318config X86_REBOOTFIXUPS 1319 bool "Enable X86 board specific fixups for reboot" 1320 depends on X86_32 1321 help 1322 This enables chipset and/or board specific fixups to be done 1323 in order to get reboot to work correctly. This is only needed on 1324 some combinations of hardware and BIOS. The symptom, for which 1325 this config is intended, is when reboot ends with a stalled/hung 1326 system. 1327 1328 Currently, the only fixup is for the Geode machines using 1329 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1330 1331 Say Y if you want to enable the fixup. Currently, it's safe to 1332 enable this option even if you don't need it. 1333 Say N otherwise. 1334 1335config MICROCODE 1336 def_bool y 1337 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1338 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD 1339 1340config MICROCODE_INITRD32 1341 def_bool y 1342 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1343 1344config MICROCODE_LATE_LOADING 1345 bool "Late microcode loading (DANGEROUS)" 1346 default n 1347 depends on MICROCODE && SMP 1348 help 1349 Loading microcode late, when the system is up and executing instructions 1350 is a tricky business and should be avoided if possible. Just the sequence 1351 of synchronizing all cores and SMT threads is one fragile dance which does 1352 not guarantee that cores might not softlock after the loading. Therefore, 1353 use this at your own risk. Late loading taints the kernel unless the 1354 microcode header indicates that it is safe for late loading via the 1355 minimal revision check. This minimal revision check can be enforced on 1356 the kernel command line with "microcode.minrev=Y". 1357 1358config MICROCODE_LATE_FORCE_MINREV 1359 bool "Enforce late microcode loading minimal revision check" 1360 default n 1361 depends on MICROCODE_LATE_LOADING 1362 help 1363 To prevent that users load microcode late which modifies already 1364 in use features, newer microcode patches have a minimum revision field 1365 in the microcode header, which tells the kernel which minimum 1366 revision must be active in the CPU to safely load that new microcode 1367 late into the running system. If disabled the check will not 1368 be enforced but the kernel will be tainted when the minimal 1369 revision check fails. 1370 1371 This minimal revision check can also be controlled via the 1372 "microcode.minrev" parameter on the kernel command line. 1373 1374 If unsure say Y. 1375 1376config X86_MSR 1377 tristate "/dev/cpu/*/msr - Model-specific register support" 1378 help 1379 This device gives privileged processes access to the x86 1380 Model-Specific Registers (MSRs). It is a character device with 1381 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1382 MSR accesses are directed to a specific CPU on multi-processor 1383 systems. 1384 1385config X86_CPUID 1386 tristate "/dev/cpu/*/cpuid - CPU information support" 1387 help 1388 This device gives processes access to the x86 CPUID instruction to 1389 be executed on a specific processor. It is a character device 1390 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1391 /dev/cpu/31/cpuid. 1392 1393choice 1394 prompt "High Memory Support" 1395 default HIGHMEM4G 1396 depends on X86_32 1397 1398config NOHIGHMEM 1399 bool "off" 1400 help 1401 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1402 However, the address space of 32-bit x86 processors is only 4 1403 Gigabytes large. That means that, if you have a large amount of 1404 physical memory, not all of it can be "permanently mapped" by the 1405 kernel. The physical memory that's not permanently mapped is called 1406 "high memory". 1407 1408 If you are compiling a kernel which will never run on a machine with 1409 more than 1 Gigabyte total physical RAM, answer "off" here (default 1410 choice and suitable for most users). This will result in a "3GB/1GB" 1411 split: 3GB are mapped so that each process sees a 3GB virtual memory 1412 space and the remaining part of the 4GB virtual memory space is used 1413 by the kernel to permanently map as much physical memory as 1414 possible. 1415 1416 If the machine has between 1 and 4 Gigabytes physical RAM, then 1417 answer "4GB" here. 1418 1419 If more than 4 Gigabytes is used then answer "64GB" here. This 1420 selection turns Intel PAE (Physical Address Extension) mode on. 1421 PAE implements 3-level paging on IA32 processors. PAE is fully 1422 supported by Linux, PAE mode is implemented on all recent Intel 1423 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1424 then the kernel will not boot on CPUs that don't support PAE! 1425 1426 The actual amount of total physical memory will either be 1427 auto detected or can be forced by using a kernel command line option 1428 such as "mem=256M". (Try "man bootparam" or see the documentation of 1429 your boot loader (lilo or loadlin) about how to pass options to the 1430 kernel at boot time.) 1431 1432 If unsure, say "off". 1433 1434config HIGHMEM4G 1435 bool "4GB" 1436 help 1437 Select this if you have a 32-bit processor and between 1 and 4 1438 gigabytes of physical RAM. 1439 1440config HIGHMEM64G 1441 bool "64GB" 1442 depends on X86_HAVE_PAE 1443 select X86_PAE 1444 help 1445 Select this if you have a 32-bit processor and more than 4 1446 gigabytes of physical RAM. 1447 1448endchoice 1449 1450choice 1451 prompt "Memory split" if EXPERT 1452 default VMSPLIT_3G 1453 depends on X86_32 1454 help 1455 Select the desired split between kernel and user memory. 1456 1457 If the address range available to the kernel is less than the 1458 physical memory installed, the remaining memory will be available 1459 as "high memory". Accessing high memory is a little more costly 1460 than low memory, as it needs to be mapped into the kernel first. 1461 Note that increasing the kernel address space limits the range 1462 available to user programs, making the address space there 1463 tighter. Selecting anything other than the default 3G/1G split 1464 will also likely make your kernel incompatible with binary-only 1465 kernel modules. 1466 1467 If you are not absolutely sure what you are doing, leave this 1468 option alone! 1469 1470 config VMSPLIT_3G 1471 bool "3G/1G user/kernel split" 1472 config VMSPLIT_3G_OPT 1473 depends on !X86_PAE 1474 bool "3G/1G user/kernel split (for full 1G low memory)" 1475 config VMSPLIT_2G 1476 bool "2G/2G user/kernel split" 1477 config VMSPLIT_2G_OPT 1478 depends on !X86_PAE 1479 bool "2G/2G user/kernel split (for full 2G low memory)" 1480 config VMSPLIT_1G 1481 bool "1G/3G user/kernel split" 1482endchoice 1483 1484config PAGE_OFFSET 1485 hex 1486 default 0xB0000000 if VMSPLIT_3G_OPT 1487 default 0x80000000 if VMSPLIT_2G 1488 default 0x78000000 if VMSPLIT_2G_OPT 1489 default 0x40000000 if VMSPLIT_1G 1490 default 0xC0000000 1491 depends on X86_32 1492 1493config HIGHMEM 1494 def_bool y 1495 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1496 1497config X86_PAE 1498 bool "PAE (Physical Address Extension) Support" 1499 depends on X86_32 && X86_HAVE_PAE 1500 select PHYS_ADDR_T_64BIT 1501 select SWIOTLB 1502 help 1503 PAE is required for NX support, and furthermore enables 1504 larger swapspace support for non-overcommit purposes. It 1505 has the cost of more pagetable lookup overhead, and also 1506 consumes more pagetable space per process. 1507 1508config X86_5LEVEL 1509 bool "Enable 5-level page tables support" 1510 default y 1511 select DYNAMIC_MEMORY_LAYOUT 1512 select SPARSEMEM_VMEMMAP 1513 depends on X86_64 1514 help 1515 5-level paging enables access to larger address space: 1516 up to 128 PiB of virtual address space and 4 PiB of 1517 physical address space. 1518 1519 It will be supported by future Intel CPUs. 1520 1521 A kernel with the option enabled can be booted on machines that 1522 support 4- or 5-level paging. 1523 1524 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1525 information. 1526 1527 Say N if unsure. 1528 1529config X86_DIRECT_GBPAGES 1530 def_bool y 1531 depends on X86_64 1532 help 1533 Certain kernel features effectively disable kernel 1534 linear 1 GB mappings (even if the CPU otherwise 1535 supports them), so don't confuse the user by printing 1536 that we have them enabled. 1537 1538config X86_CPA_STATISTICS 1539 bool "Enable statistic for Change Page Attribute" 1540 depends on DEBUG_FS 1541 help 1542 Expose statistics about the Change Page Attribute mechanism, which 1543 helps to determine the effectiveness of preserving large and huge 1544 page mappings when mapping protections are changed. 1545 1546config X86_MEM_ENCRYPT 1547 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1548 select DYNAMIC_PHYSICAL_MASK 1549 def_bool n 1550 1551config AMD_MEM_ENCRYPT 1552 bool "AMD Secure Memory Encryption (SME) support" 1553 depends on X86_64 && CPU_SUP_AMD 1554 depends on EFI_STUB 1555 select DMA_COHERENT_POOL 1556 select ARCH_USE_MEMREMAP_PROT 1557 select INSTRUCTION_DECODER 1558 select ARCH_HAS_CC_PLATFORM 1559 select X86_MEM_ENCRYPT 1560 select UNACCEPTED_MEMORY 1561 help 1562 Say yes to enable support for the encryption of system memory. 1563 This requires an AMD processor that supports Secure Memory 1564 Encryption (SME). 1565 1566# Common NUMA Features 1567config NUMA 1568 bool "NUMA Memory Allocation and Scheduler Support" 1569 depends on SMP 1570 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1571 default y if X86_BIGSMP 1572 select USE_PERCPU_NUMA_NODE_ID 1573 select OF_NUMA if OF 1574 help 1575 Enable NUMA (Non-Uniform Memory Access) support. 1576 1577 The kernel will try to allocate memory used by a CPU on the 1578 local memory controller of the CPU and add some more 1579 NUMA awareness to the kernel. 1580 1581 For 64-bit this is recommended if the system is Intel Core i7 1582 (or later), AMD Opteron, or EM64T NUMA. 1583 1584 For 32-bit this is only needed if you boot a 32-bit 1585 kernel on a 64-bit NUMA platform. 1586 1587 Otherwise, you should say N. 1588 1589config AMD_NUMA 1590 def_bool y 1591 prompt "Old style AMD Opteron NUMA detection" 1592 depends on X86_64 && NUMA && PCI 1593 help 1594 Enable AMD NUMA node topology detection. You should say Y here if 1595 you have a multi processor AMD system. This uses an old method to 1596 read the NUMA configuration directly from the builtin Northbridge 1597 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1598 which also takes priority if both are compiled in. 1599 1600config X86_64_ACPI_NUMA 1601 def_bool y 1602 prompt "ACPI NUMA detection" 1603 depends on X86_64 && NUMA && ACPI && PCI 1604 select ACPI_NUMA 1605 help 1606 Enable ACPI SRAT based node topology detection. 1607 1608config NODES_SHIFT 1609 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1610 range 1 10 1611 default "10" if MAXSMP 1612 default "6" if X86_64 1613 default "3" 1614 depends on NUMA 1615 help 1616 Specify the maximum number of NUMA Nodes available on the target 1617 system. Increases memory reserved to accommodate various tables. 1618 1619config ARCH_FLATMEM_ENABLE 1620 def_bool y 1621 depends on X86_32 && !NUMA 1622 1623config ARCH_SPARSEMEM_ENABLE 1624 def_bool y 1625 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1626 select SPARSEMEM_STATIC if X86_32 1627 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1628 1629config ARCH_SPARSEMEM_DEFAULT 1630 def_bool X86_64 || (NUMA && X86_32) 1631 1632config ARCH_SELECT_MEMORY_MODEL 1633 def_bool y 1634 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1635 1636config ARCH_MEMORY_PROBE 1637 bool "Enable sysfs memory/probe interface" 1638 depends on MEMORY_HOTPLUG 1639 help 1640 This option enables a sysfs memory/probe interface for testing. 1641 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1642 If you are unsure how to answer this question, answer N. 1643 1644config ARCH_PROC_KCORE_TEXT 1645 def_bool y 1646 depends on X86_64 && PROC_KCORE 1647 1648config ILLEGAL_POINTER_VALUE 1649 hex 1650 default 0 if X86_32 1651 default 0xdead000000000000 if X86_64 1652 1653config X86_PMEM_LEGACY_DEVICE 1654 bool 1655 1656config X86_PMEM_LEGACY 1657 tristate "Support non-standard NVDIMMs and ADR protected memory" 1658 depends on PHYS_ADDR_T_64BIT 1659 depends on BLK_DEV 1660 select X86_PMEM_LEGACY_DEVICE 1661 select NUMA_KEEP_MEMINFO if NUMA 1662 select LIBNVDIMM 1663 help 1664 Treat memory marked using the non-standard e820 type of 12 as used 1665 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1666 The kernel will offer these regions to the 'pmem' driver so 1667 they can be used for persistent storage. 1668 1669 Say Y if unsure. 1670 1671config HIGHPTE 1672 bool "Allocate 3rd-level pagetables from highmem" 1673 depends on HIGHMEM 1674 help 1675 The VM uses one page table entry for each page of physical memory. 1676 For systems with a lot of RAM, this can be wasteful of precious 1677 low memory. Setting this option will put user-space page table 1678 entries in high memory. 1679 1680config X86_CHECK_BIOS_CORRUPTION 1681 bool "Check for low memory corruption" 1682 help 1683 Periodically check for memory corruption in low memory, which 1684 is suspected to be caused by BIOS. Even when enabled in the 1685 configuration, it is disabled at runtime. Enable it by 1686 setting "memory_corruption_check=1" on the kernel command 1687 line. By default it scans the low 64k of memory every 60 1688 seconds; see the memory_corruption_check_size and 1689 memory_corruption_check_period parameters in 1690 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1691 1692 When enabled with the default parameters, this option has 1693 almost no overhead, as it reserves a relatively small amount 1694 of memory and scans it infrequently. It both detects corruption 1695 and prevents it from affecting the running system. 1696 1697 It is, however, intended as a diagnostic tool; if repeatable 1698 BIOS-originated corruption always affects the same memory, 1699 you can use memmap= to prevent the kernel from using that 1700 memory. 1701 1702config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1703 bool "Set the default setting of memory_corruption_check" 1704 depends on X86_CHECK_BIOS_CORRUPTION 1705 default y 1706 help 1707 Set whether the default state of memory_corruption_check is 1708 on or off. 1709 1710config MATH_EMULATION 1711 bool 1712 depends on MODIFY_LDT_SYSCALL 1713 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1714 help 1715 Linux can emulate a math coprocessor (used for floating point 1716 operations) if you don't have one. 486DX and Pentium processors have 1717 a math coprocessor built in, 486SX and 386 do not, unless you added 1718 a 487DX or 387, respectively. (The messages during boot time can 1719 give you some hints here ["man dmesg"].) Everyone needs either a 1720 coprocessor or this emulation. 1721 1722 If you don't have a math coprocessor, you need to say Y here; if you 1723 say Y here even though you have a coprocessor, the coprocessor will 1724 be used nevertheless. (This behavior can be changed with the kernel 1725 command line option "no387", which comes handy if your coprocessor 1726 is broken. Try "man bootparam" or see the documentation of your boot 1727 loader (lilo or loadlin) about how to pass options to the kernel at 1728 boot time.) This means that it is a good idea to say Y here if you 1729 intend to use this kernel on different machines. 1730 1731 More information about the internals of the Linux math coprocessor 1732 emulation can be found in <file:arch/x86/math-emu/README>. 1733 1734 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1735 kernel, it won't hurt. 1736 1737config MTRR 1738 def_bool y 1739 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1740 help 1741 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1742 the Memory Type Range Registers (MTRRs) may be used to control 1743 processor access to memory ranges. This is most useful if you have 1744 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1745 allows bus write transfers to be combined into a larger transfer 1746 before bursting over the PCI/AGP bus. This can increase performance 1747 of image write operations 2.5 times or more. Saying Y here creates a 1748 /proc/mtrr file which may be used to manipulate your processor's 1749 MTRRs. Typically the X server should use this. 1750 1751 This code has a reasonably generic interface so that similar 1752 control registers on other processors can be easily supported 1753 as well: 1754 1755 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1756 Registers (ARRs) which provide a similar functionality to MTRRs. For 1757 these, the ARRs are used to emulate the MTRRs. 1758 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1759 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1760 write-combining. All of these processors are supported by this code 1761 and it makes sense to say Y here if you have one of them. 1762 1763 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1764 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1765 can lead to all sorts of problems, so it's good to say Y here. 1766 1767 You can safely say Y even if your machine doesn't have MTRRs, you'll 1768 just add about 9 KB to your kernel. 1769 1770 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1771 1772config MTRR_SANITIZER 1773 def_bool y 1774 prompt "MTRR cleanup support" 1775 depends on MTRR 1776 help 1777 Convert MTRR layout from continuous to discrete, so X drivers can 1778 add writeback entries. 1779 1780 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1781 The largest mtrr entry size for a continuous block can be set with 1782 mtrr_chunk_size. 1783 1784 If unsure, say Y. 1785 1786config MTRR_SANITIZER_ENABLE_DEFAULT 1787 int "MTRR cleanup enable value (0-1)" 1788 range 0 1 1789 default "0" 1790 depends on MTRR_SANITIZER 1791 help 1792 Enable mtrr cleanup default value 1793 1794config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1795 int "MTRR cleanup spare reg num (0-7)" 1796 range 0 7 1797 default "1" 1798 depends on MTRR_SANITIZER 1799 help 1800 mtrr cleanup spare entries default, it can be changed via 1801 mtrr_spare_reg_nr=N on the kernel command line. 1802 1803config X86_PAT 1804 def_bool y 1805 prompt "x86 PAT support" if EXPERT 1806 depends on MTRR 1807 select ARCH_USES_PG_ARCH_2 1808 help 1809 Use PAT attributes to setup page level cache control. 1810 1811 PATs are the modern equivalents of MTRRs and are much more 1812 flexible than MTRRs. 1813 1814 Say N here if you see bootup problems (boot crash, boot hang, 1815 spontaneous reboots) or a non-working video driver. 1816 1817 If unsure, say Y. 1818 1819config X86_UMIP 1820 def_bool y 1821 prompt "User Mode Instruction Prevention" if EXPERT 1822 help 1823 User Mode Instruction Prevention (UMIP) is a security feature in 1824 some x86 processors. If enabled, a general protection fault is 1825 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1826 executed in user mode. These instructions unnecessarily expose 1827 information about the hardware state. 1828 1829 The vast majority of applications do not use these instructions. 1830 For the very few that do, software emulation is provided in 1831 specific cases in protected and virtual-8086 modes. Emulated 1832 results are dummy. 1833 1834config CC_HAS_IBT 1835 # GCC >= 9 and binutils >= 2.29 1836 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1837 # Clang/LLVM >= 14 1838 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1839 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1840 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1841 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1842 $(as-instr,endbr64) 1843 1844config X86_CET 1845 def_bool n 1846 help 1847 CET features configured (Shadow stack or IBT) 1848 1849config X86_KERNEL_IBT 1850 prompt "Indirect Branch Tracking" 1851 def_bool y 1852 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1853 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1854 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1855 select OBJTOOL 1856 select X86_CET 1857 help 1858 Build the kernel with support for Indirect Branch Tracking, a 1859 hardware support course-grain forward-edge Control Flow Integrity 1860 protection. It enforces that all indirect calls must land on 1861 an ENDBR instruction, as such, the compiler will instrument the 1862 code with them to make this happen. 1863 1864 In addition to building the kernel with IBT, seal all functions that 1865 are not indirect call targets, avoiding them ever becoming one. 1866 1867 This requires LTO like objtool runs and will slow down the build. It 1868 does significantly reduce the number of ENDBR instructions in the 1869 kernel image. 1870 1871config X86_INTEL_MEMORY_PROTECTION_KEYS 1872 prompt "Memory Protection Keys" 1873 def_bool y 1874 # Note: only available in 64-bit mode 1875 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1876 select ARCH_USES_HIGH_VMA_FLAGS 1877 select ARCH_HAS_PKEYS 1878 help 1879 Memory Protection Keys provides a mechanism for enforcing 1880 page-based protections, but without requiring modification of the 1881 page tables when an application changes protection domains. 1882 1883 For details, see Documentation/core-api/protection-keys.rst 1884 1885 If unsure, say y. 1886 1887config ARCH_PKEY_BITS 1888 int 1889 default 4 1890 1891choice 1892 prompt "TSX enable mode" 1893 depends on CPU_SUP_INTEL 1894 default X86_INTEL_TSX_MODE_OFF 1895 help 1896 Intel's TSX (Transactional Synchronization Extensions) feature 1897 allows to optimize locking protocols through lock elision which 1898 can lead to a noticeable performance boost. 1899 1900 On the other hand it has been shown that TSX can be exploited 1901 to form side channel attacks (e.g. TAA) and chances are there 1902 will be more of those attacks discovered in the future. 1903 1904 Therefore TSX is not enabled by default (aka tsx=off). An admin 1905 might override this decision by tsx=on the command line parameter. 1906 Even with TSX enabled, the kernel will attempt to enable the best 1907 possible TAA mitigation setting depending on the microcode available 1908 for the particular machine. 1909 1910 This option allows to set the default tsx mode between tsx=on, =off 1911 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1912 details. 1913 1914 Say off if not sure, auto if TSX is in use but it should be used on safe 1915 platforms or on if TSX is in use and the security aspect of tsx is not 1916 relevant. 1917 1918config X86_INTEL_TSX_MODE_OFF 1919 bool "off" 1920 help 1921 TSX is disabled if possible - equals to tsx=off command line parameter. 1922 1923config X86_INTEL_TSX_MODE_ON 1924 bool "on" 1925 help 1926 TSX is always enabled on TSX capable HW - equals the tsx=on command 1927 line parameter. 1928 1929config X86_INTEL_TSX_MODE_AUTO 1930 bool "auto" 1931 help 1932 TSX is enabled on TSX capable HW that is believed to be safe against 1933 side channel attacks- equals the tsx=auto command line parameter. 1934endchoice 1935 1936config X86_SGX 1937 bool "Software Guard eXtensions (SGX)" 1938 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1939 depends on CRYPTO=y 1940 depends on CRYPTO_SHA256=y 1941 select MMU_NOTIFIER 1942 select NUMA_KEEP_MEMINFO if NUMA 1943 select XARRAY_MULTI 1944 help 1945 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1946 that can be used by applications to set aside private regions of code 1947 and data, referred to as enclaves. An enclave's private memory can 1948 only be accessed by code running within the enclave. Accesses from 1949 outside the enclave, including other enclaves, are disallowed by 1950 hardware. 1951 1952 If unsure, say N. 1953 1954config X86_USER_SHADOW_STACK 1955 bool "X86 userspace shadow stack" 1956 depends on AS_WRUSS 1957 depends on X86_64 1958 select ARCH_USES_HIGH_VMA_FLAGS 1959 select X86_CET 1960 help 1961 Shadow stack protection is a hardware feature that detects function 1962 return address corruption. This helps mitigate ROP attacks. 1963 Applications must be enabled to use it, and old userspace does not 1964 get protection "for free". 1965 1966 CPUs supporting shadow stacks were first released in 2020. 1967 1968 See Documentation/arch/x86/shstk.rst for more information. 1969 1970 If unsure, say N. 1971 1972config INTEL_TDX_HOST 1973 bool "Intel Trust Domain Extensions (TDX) host support" 1974 depends on CPU_SUP_INTEL 1975 depends on X86_64 1976 depends on KVM_INTEL 1977 depends on X86_X2APIC 1978 select ARCH_KEEP_MEMBLOCK 1979 depends on CONTIG_ALLOC 1980 depends on !KEXEC_CORE 1981 depends on X86_MCE 1982 help 1983 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1984 host and certain physical attacks. This option enables necessary TDX 1985 support in the host kernel to run confidential VMs. 1986 1987 If unsure, say N. 1988 1989config EFI 1990 bool "EFI runtime service support" 1991 depends on ACPI 1992 select UCS2_STRING 1993 select EFI_RUNTIME_WRAPPERS 1994 select ARCH_USE_MEMREMAP_PROT 1995 select EFI_RUNTIME_MAP if KEXEC_CORE 1996 help 1997 This enables the kernel to use EFI runtime services that are 1998 available (such as the EFI variable services). 1999 2000 This option is only useful on systems that have EFI firmware. 2001 In addition, you should use the latest ELILO loader available 2002 at <http://elilo.sourceforge.net> in order to take advantage 2003 of EFI runtime services. However, even with this option, the 2004 resultant kernel should continue to boot on existing non-EFI 2005 platforms. 2006 2007config EFI_STUB 2008 bool "EFI stub support" 2009 depends on EFI 2010 select RELOCATABLE 2011 help 2012 This kernel feature allows a bzImage to be loaded directly 2013 by EFI firmware without the use of a bootloader. 2014 2015 See Documentation/admin-guide/efi-stub.rst for more information. 2016 2017config EFI_HANDOVER_PROTOCOL 2018 bool "EFI handover protocol (DEPRECATED)" 2019 depends on EFI_STUB 2020 default y 2021 help 2022 Select this in order to include support for the deprecated EFI 2023 handover protocol, which defines alternative entry points into the 2024 EFI stub. This is a practice that has no basis in the UEFI 2025 specification, and requires a priori knowledge on the part of the 2026 bootloader about Linux/x86 specific ways of passing the command line 2027 and initrd, and where in memory those assets may be loaded. 2028 2029 If in doubt, say Y. Even though the corresponding support is not 2030 present in upstream GRUB or other bootloaders, most distros build 2031 GRUB with numerous downstream patches applied, and may rely on the 2032 handover protocol as as result. 2033 2034config EFI_MIXED 2035 bool "EFI mixed-mode support" 2036 depends on EFI_STUB && X86_64 2037 help 2038 Enabling this feature allows a 64-bit kernel to be booted 2039 on a 32-bit firmware, provided that your CPU supports 64-bit 2040 mode. 2041 2042 Note that it is not possible to boot a mixed-mode enabled 2043 kernel via the EFI boot stub - a bootloader that supports 2044 the EFI handover protocol must be used. 2045 2046 If unsure, say N. 2047 2048config EFI_RUNTIME_MAP 2049 bool "Export EFI runtime maps to sysfs" if EXPERT 2050 depends on EFI 2051 help 2052 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2053 That memory map is required by the 2nd kernel to set up EFI virtual 2054 mappings after kexec, but can also be used for debugging purposes. 2055 2056 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2057 2058source "kernel/Kconfig.hz" 2059 2060config ARCH_SUPPORTS_KEXEC 2061 def_bool y 2062 2063config ARCH_SUPPORTS_KEXEC_FILE 2064 def_bool X86_64 2065 2066config ARCH_SELECTS_KEXEC_FILE 2067 def_bool y 2068 depends on KEXEC_FILE 2069 select HAVE_IMA_KEXEC if IMA 2070 2071config ARCH_SUPPORTS_KEXEC_PURGATORY 2072 def_bool y 2073 2074config ARCH_SUPPORTS_KEXEC_SIG 2075 def_bool y 2076 2077config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2078 def_bool y 2079 2080config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2081 def_bool y 2082 2083config ARCH_SUPPORTS_KEXEC_JUMP 2084 def_bool y 2085 2086config ARCH_SUPPORTS_CRASH_DUMP 2087 def_bool X86_64 || (X86_32 && HIGHMEM) 2088 2089config ARCH_DEFAULT_CRASH_DUMP 2090 def_bool y 2091 2092config ARCH_SUPPORTS_CRASH_HOTPLUG 2093 def_bool y 2094 2095config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2096 def_bool CRASH_RESERVE 2097 2098config PHYSICAL_START 2099 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2100 default "0x1000000" 2101 help 2102 This gives the physical address where the kernel is loaded. 2103 2104 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2105 will decompress itself to above physical address and run from there. 2106 Otherwise, bzImage will run from the address where it has been loaded 2107 by the boot loader. The only exception is if it is loaded below the 2108 above physical address, in which case it will relocate itself there. 2109 2110 In normal kdump cases one does not have to set/change this option 2111 as now bzImage can be compiled as a completely relocatable image 2112 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2113 address. This option is mainly useful for the folks who don't want 2114 to use a bzImage for capturing the crash dump and want to use a 2115 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2116 to be specifically compiled to run from a specific memory area 2117 (normally a reserved region) and this option comes handy. 2118 2119 So if you are using bzImage for capturing the crash dump, 2120 leave the value here unchanged to 0x1000000 and set 2121 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2122 for capturing the crash dump change this value to start of 2123 the reserved region. In other words, it can be set based on 2124 the "X" value as specified in the "crashkernel=YM@XM" 2125 command line boot parameter passed to the panic-ed 2126 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2127 for more details about crash dumps. 2128 2129 Usage of bzImage for capturing the crash dump is recommended as 2130 one does not have to build two kernels. Same kernel can be used 2131 as production kernel and capture kernel. Above option should have 2132 gone away after relocatable bzImage support is introduced. But it 2133 is present because there are users out there who continue to use 2134 vmlinux for dump capture. This option should go away down the 2135 line. 2136 2137 Don't change this unless you know what you are doing. 2138 2139config RELOCATABLE 2140 bool "Build a relocatable kernel" 2141 default y 2142 help 2143 This builds a kernel image that retains relocation information 2144 so it can be loaded someplace besides the default 1MB. 2145 The relocations tend to make the kernel binary about 10% larger, 2146 but are discarded at runtime. 2147 2148 One use is for the kexec on panic case where the recovery kernel 2149 must live at a different physical address than the primary 2150 kernel. 2151 2152 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2153 it has been loaded at and the compile time physical address 2154 (CONFIG_PHYSICAL_START) is used as the minimum location. 2155 2156config RANDOMIZE_BASE 2157 bool "Randomize the address of the kernel image (KASLR)" 2158 depends on RELOCATABLE 2159 default y 2160 help 2161 In support of Kernel Address Space Layout Randomization (KASLR), 2162 this randomizes the physical address at which the kernel image 2163 is decompressed and the virtual address where the kernel 2164 image is mapped, as a security feature that deters exploit 2165 attempts relying on knowledge of the location of kernel 2166 code internals. 2167 2168 On 64-bit, the kernel physical and virtual addresses are 2169 randomized separately. The physical address will be anywhere 2170 between 16MB and the top of physical memory (up to 64TB). The 2171 virtual address will be randomized from 16MB up to 1GB (9 bits 2172 of entropy). Note that this also reduces the memory space 2173 available to kernel modules from 1.5GB to 1GB. 2174 2175 On 32-bit, the kernel physical and virtual addresses are 2176 randomized together. They will be randomized from 16MB up to 2177 512MB (8 bits of entropy). 2178 2179 Entropy is generated using the RDRAND instruction if it is 2180 supported. If RDTSC is supported, its value is mixed into 2181 the entropy pool as well. If neither RDRAND nor RDTSC are 2182 supported, then entropy is read from the i8254 timer. The 2183 usable entropy is limited by the kernel being built using 2184 2GB addressing, and that PHYSICAL_ALIGN must be at a 2185 minimum of 2MB. As a result, only 10 bits of entropy are 2186 theoretically possible, but the implementations are further 2187 limited due to memory layouts. 2188 2189 If unsure, say Y. 2190 2191# Relocation on x86 needs some additional build support 2192config X86_NEED_RELOCS 2193 def_bool y 2194 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2195 2196config PHYSICAL_ALIGN 2197 hex "Alignment value to which kernel should be aligned" 2198 default "0x200000" 2199 range 0x2000 0x1000000 if X86_32 2200 range 0x200000 0x1000000 if X86_64 2201 help 2202 This value puts the alignment restrictions on physical address 2203 where kernel is loaded and run from. Kernel is compiled for an 2204 address which meets above alignment restriction. 2205 2206 If bootloader loads the kernel at a non-aligned address and 2207 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2208 address aligned to above value and run from there. 2209 2210 If bootloader loads the kernel at a non-aligned address and 2211 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2212 load address and decompress itself to the address it has been 2213 compiled for and run from there. The address for which kernel is 2214 compiled already meets above alignment restrictions. Hence the 2215 end result is that kernel runs from a physical address meeting 2216 above alignment restrictions. 2217 2218 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2219 this value must be a multiple of 0x200000. 2220 2221 Don't change this unless you know what you are doing. 2222 2223config DYNAMIC_MEMORY_LAYOUT 2224 bool 2225 help 2226 This option makes base addresses of vmalloc and vmemmap as well as 2227 __PAGE_OFFSET movable during boot. 2228 2229config RANDOMIZE_MEMORY 2230 bool "Randomize the kernel memory sections" 2231 depends on X86_64 2232 depends on RANDOMIZE_BASE 2233 select DYNAMIC_MEMORY_LAYOUT 2234 default RANDOMIZE_BASE 2235 help 2236 Randomizes the base virtual address of kernel memory sections 2237 (physical memory mapping, vmalloc & vmemmap). This security feature 2238 makes exploits relying on predictable memory locations less reliable. 2239 2240 The order of allocations remains unchanged. Entropy is generated in 2241 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2242 configuration have in average 30,000 different possible virtual 2243 addresses for each memory section. 2244 2245 If unsure, say Y. 2246 2247config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2248 hex "Physical memory mapping padding" if EXPERT 2249 depends on RANDOMIZE_MEMORY 2250 default "0xa" if MEMORY_HOTPLUG 2251 default "0x0" 2252 range 0x1 0x40 if MEMORY_HOTPLUG 2253 range 0x0 0x40 2254 help 2255 Define the padding in terabytes added to the existing physical 2256 memory size during kernel memory randomization. It is useful 2257 for memory hotplug support but reduces the entropy available for 2258 address randomization. 2259 2260 If unsure, leave at the default value. 2261 2262config ADDRESS_MASKING 2263 bool "Linear Address Masking support" 2264 depends on X86_64 2265 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2266 help 2267 Linear Address Masking (LAM) modifies the checking that is applied 2268 to 64-bit linear addresses, allowing software to use of the 2269 untranslated address bits for metadata. 2270 2271 The capability can be used for efficient address sanitizers (ASAN) 2272 implementation and for optimizations in JITs. 2273 2274config HOTPLUG_CPU 2275 def_bool y 2276 depends on SMP 2277 2278config COMPAT_VDSO 2279 def_bool n 2280 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2281 depends on COMPAT_32 2282 help 2283 Certain buggy versions of glibc will crash if they are 2284 presented with a 32-bit vDSO that is not mapped at the address 2285 indicated in its segment table. 2286 2287 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2288 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2289 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2290 the only released version with the bug, but OpenSUSE 9 2291 contains a buggy "glibc 2.3.2". 2292 2293 The symptom of the bug is that everything crashes on startup, saying: 2294 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2295 2296 Saying Y here changes the default value of the vdso32 boot 2297 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2298 This works around the glibc bug but hurts performance. 2299 2300 If unsure, say N: if you are compiling your own kernel, you 2301 are unlikely to be using a buggy version of glibc. 2302 2303choice 2304 prompt "vsyscall table for legacy applications" 2305 depends on X86_64 2306 default LEGACY_VSYSCALL_XONLY 2307 help 2308 Legacy user code that does not know how to find the vDSO expects 2309 to be able to issue three syscalls by calling fixed addresses in 2310 kernel space. Since this location is not randomized with ASLR, 2311 it can be used to assist security vulnerability exploitation. 2312 2313 This setting can be changed at boot time via the kernel command 2314 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2315 is deprecated and can only be enabled using the kernel command 2316 line. 2317 2318 On a system with recent enough glibc (2.14 or newer) and no 2319 static binaries, you can say None without a performance penalty 2320 to improve security. 2321 2322 If unsure, select "Emulate execution only". 2323 2324 config LEGACY_VSYSCALL_XONLY 2325 bool "Emulate execution only" 2326 help 2327 The kernel traps and emulates calls into the fixed vsyscall 2328 address mapping and does not allow reads. This 2329 configuration is recommended when userspace might use the 2330 legacy vsyscall area but support for legacy binary 2331 instrumentation of legacy code is not needed. It mitigates 2332 certain uses of the vsyscall area as an ASLR-bypassing 2333 buffer. 2334 2335 config LEGACY_VSYSCALL_NONE 2336 bool "None" 2337 help 2338 There will be no vsyscall mapping at all. This will 2339 eliminate any risk of ASLR bypass due to the vsyscall 2340 fixed address mapping. Attempts to use the vsyscalls 2341 will be reported to dmesg, so that either old or 2342 malicious userspace programs can be identified. 2343 2344endchoice 2345 2346config CMDLINE_BOOL 2347 bool "Built-in kernel command line" 2348 help 2349 Allow for specifying boot arguments to the kernel at 2350 build time. On some systems (e.g. embedded ones), it is 2351 necessary or convenient to provide some or all of the 2352 kernel boot arguments with the kernel itself (that is, 2353 to not rely on the boot loader to provide them.) 2354 2355 To compile command line arguments into the kernel, 2356 set this option to 'Y', then fill in the 2357 boot arguments in CONFIG_CMDLINE. 2358 2359 Systems with fully functional boot loaders (i.e. non-embedded) 2360 should leave this option set to 'N'. 2361 2362config CMDLINE 2363 string "Built-in kernel command string" 2364 depends on CMDLINE_BOOL 2365 default "" 2366 help 2367 Enter arguments here that should be compiled into the kernel 2368 image and used at boot time. If the boot loader provides a 2369 command line at boot time, it is appended to this string to 2370 form the full kernel command line, when the system boots. 2371 2372 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2373 change this behavior. 2374 2375 In most cases, the command line (whether built-in or provided 2376 by the boot loader) should specify the device for the root 2377 file system. 2378 2379config CMDLINE_OVERRIDE 2380 bool "Built-in command line overrides boot loader arguments" 2381 depends on CMDLINE_BOOL && CMDLINE != "" 2382 help 2383 Set this option to 'Y' to have the kernel ignore the boot loader 2384 command line, and use ONLY the built-in command line. 2385 2386 This is used to work around broken boot loaders. This should 2387 be set to 'N' under normal conditions. 2388 2389config MODIFY_LDT_SYSCALL 2390 bool "Enable the LDT (local descriptor table)" if EXPERT 2391 default y 2392 help 2393 Linux can allow user programs to install a per-process x86 2394 Local Descriptor Table (LDT) using the modify_ldt(2) system 2395 call. This is required to run 16-bit or segmented code such as 2396 DOSEMU or some Wine programs. It is also used by some very old 2397 threading libraries. 2398 2399 Enabling this feature adds a small amount of overhead to 2400 context switches and increases the low-level kernel attack 2401 surface. Disabling it removes the modify_ldt(2) system call. 2402 2403 Saying 'N' here may make sense for embedded or server kernels. 2404 2405config STRICT_SIGALTSTACK_SIZE 2406 bool "Enforce strict size checking for sigaltstack" 2407 depends on DYNAMIC_SIGFRAME 2408 help 2409 For historical reasons MINSIGSTKSZ is a constant which became 2410 already too small with AVX512 support. Add a mechanism to 2411 enforce strict checking of the sigaltstack size against the 2412 real size of the FPU frame. This option enables the check 2413 by default. It can also be controlled via the kernel command 2414 line option 'strict_sas_size' independent of this config 2415 switch. Enabling it might break existing applications which 2416 allocate a too small sigaltstack but 'work' because they 2417 never get a signal delivered. 2418 2419 Say 'N' unless you want to really enforce this check. 2420 2421config CFI_AUTO_DEFAULT 2422 bool "Attempt to use FineIBT by default at boot time" 2423 depends on FINEIBT 2424 depends on !RUST || RUSTC_VERSION >= 108800 2425 default y 2426 help 2427 Attempt to use FineIBT by default at boot time. If enabled, 2428 this is the same as booting with "cfi=auto". If disabled, 2429 this is the same as booting with "cfi=kcfi". 2430 2431source "kernel/livepatch/Kconfig" 2432 2433endmenu 2434 2435config CC_HAS_NAMED_AS 2436 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null) 2437 depends on CC_IS_GCC 2438 2439# 2440# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN) 2441# are incompatible with named address spaces with GCC < 13.3 2442# (see GCC PR sanitizer/111736 and also PR sanitizer/115172). 2443# 2444 2445config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2446 def_bool y 2447 depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300 2448 depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200 2449 2450config USE_X86_SEG_SUPPORT 2451 def_bool CC_HAS_NAMED_AS 2452 depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS 2453 2454config CC_HAS_SLS 2455 def_bool $(cc-option,-mharden-sls=all) 2456 2457config CC_HAS_RETURN_THUNK 2458 def_bool $(cc-option,-mfunction-return=thunk-extern) 2459 2460config CC_HAS_ENTRY_PADDING 2461 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2462 2463config FUNCTION_PADDING_CFI 2464 int 2465 default 59 if FUNCTION_ALIGNMENT_64B 2466 default 27 if FUNCTION_ALIGNMENT_32B 2467 default 11 if FUNCTION_ALIGNMENT_16B 2468 default 3 if FUNCTION_ALIGNMENT_8B 2469 default 0 2470 2471# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2472# except Kconfig can't do arithmetic :/ 2473config FUNCTION_PADDING_BYTES 2474 int 2475 default FUNCTION_PADDING_CFI if CFI_CLANG 2476 default FUNCTION_ALIGNMENT 2477 2478config CALL_PADDING 2479 def_bool n 2480 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2481 select FUNCTION_ALIGNMENT_16B 2482 2483config FINEIBT 2484 def_bool y 2485 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE 2486 select CALL_PADDING 2487 2488config HAVE_CALL_THUNKS 2489 def_bool y 2490 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2491 2492config CALL_THUNKS 2493 def_bool n 2494 select CALL_PADDING 2495 2496config PREFIX_SYMBOLS 2497 def_bool y 2498 depends on CALL_PADDING && !CFI_CLANG 2499 2500menuconfig CPU_MITIGATIONS 2501 bool "Mitigations for CPU vulnerabilities" 2502 default y 2503 help 2504 Say Y here to enable options which enable mitigations for hardware 2505 vulnerabilities (usually related to speculative execution). 2506 Mitigations can be disabled or restricted to SMT systems at runtime 2507 via the "mitigations" kernel parameter. 2508 2509 If you say N, all mitigations will be disabled. This CANNOT be 2510 overridden at runtime. 2511 2512 Say 'Y', unless you really know what you are doing. 2513 2514if CPU_MITIGATIONS 2515 2516config MITIGATION_PAGE_TABLE_ISOLATION 2517 bool "Remove the kernel mapping in user mode" 2518 default y 2519 depends on (X86_64 || X86_PAE) 2520 help 2521 This feature reduces the number of hardware side channels by 2522 ensuring that the majority of kernel addresses are not mapped 2523 into userspace. 2524 2525 See Documentation/arch/x86/pti.rst for more details. 2526 2527config MITIGATION_RETPOLINE 2528 bool "Avoid speculative indirect branches in kernel" 2529 select OBJTOOL if HAVE_OBJTOOL 2530 default y 2531 help 2532 Compile kernel with the retpoline compiler options to guard against 2533 kernel-to-user data leaks by avoiding speculative indirect 2534 branches. Requires a compiler with -mindirect-branch=thunk-extern 2535 support for full protection. The kernel may run slower. 2536 2537config MITIGATION_RETHUNK 2538 bool "Enable return-thunks" 2539 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2540 select OBJTOOL if HAVE_OBJTOOL 2541 default y if X86_64 2542 help 2543 Compile the kernel with the return-thunks compiler option to guard 2544 against kernel-to-user data leaks by avoiding return speculation. 2545 Requires a compiler with -mfunction-return=thunk-extern 2546 support for full protection. The kernel may run slower. 2547 2548config MITIGATION_UNRET_ENTRY 2549 bool "Enable UNRET on kernel entry" 2550 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2551 default y 2552 help 2553 Compile the kernel with support for the retbleed=unret mitigation. 2554 2555config MITIGATION_CALL_DEPTH_TRACKING 2556 bool "Mitigate RSB underflow with call depth tracking" 2557 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2558 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2559 select CALL_THUNKS 2560 default y 2561 help 2562 Compile the kernel with call depth tracking to mitigate the Intel 2563 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2564 mitigation is off by default and needs to be enabled on the 2565 kernel command line via the retbleed=stuff option. For 2566 non-affected systems the overhead of this option is marginal as 2567 the call depth tracking is using run-time generated call thunks 2568 in a compiler generated padding area and call patching. This 2569 increases text size by ~5%. For non affected systems this space 2570 is unused. On affected SKL systems this results in a significant 2571 performance gain over the IBRS mitigation. 2572 2573config CALL_THUNKS_DEBUG 2574 bool "Enable call thunks and call depth tracking debugging" 2575 depends on MITIGATION_CALL_DEPTH_TRACKING 2576 select FUNCTION_ALIGNMENT_32B 2577 default n 2578 help 2579 Enable call/ret counters for imbalance detection and build in 2580 a noisy dmesg about callthunks generation and call patching for 2581 trouble shooting. The debug prints need to be enabled on the 2582 kernel command line with 'debug-callthunks'. 2583 Only enable this when you are debugging call thunks as this 2584 creates a noticeable runtime overhead. If unsure say N. 2585 2586config MITIGATION_IBPB_ENTRY 2587 bool "Enable IBPB on kernel entry" 2588 depends on CPU_SUP_AMD && X86_64 2589 default y 2590 help 2591 Compile the kernel with support for the retbleed=ibpb and 2592 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations. 2593 2594config MITIGATION_IBRS_ENTRY 2595 bool "Enable IBRS on kernel entry" 2596 depends on CPU_SUP_INTEL && X86_64 2597 default y 2598 help 2599 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2600 This mitigates both spectre_v2 and retbleed at great cost to 2601 performance. 2602 2603config MITIGATION_SRSO 2604 bool "Mitigate speculative RAS overflow on AMD" 2605 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2606 default y 2607 help 2608 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2609 2610config MITIGATION_SLS 2611 bool "Mitigate Straight-Line-Speculation" 2612 depends on CC_HAS_SLS && X86_64 2613 select OBJTOOL if HAVE_OBJTOOL 2614 default n 2615 help 2616 Compile the kernel with straight-line-speculation options to guard 2617 against straight line speculation. The kernel image might be slightly 2618 larger. 2619 2620config MITIGATION_GDS 2621 bool "Mitigate Gather Data Sampling" 2622 depends on CPU_SUP_INTEL 2623 default y 2624 help 2625 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware 2626 vulnerability which allows unprivileged speculative access to data 2627 which was previously stored in vector registers. The attacker uses gather 2628 instructions to infer the stale vector register data. 2629 2630config MITIGATION_RFDS 2631 bool "RFDS Mitigation" 2632 depends on CPU_SUP_INTEL 2633 default y 2634 help 2635 Enable mitigation for Register File Data Sampling (RFDS) by default. 2636 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2637 allows unprivileged speculative access to stale data previously 2638 stored in floating point, vector and integer registers. 2639 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2640 2641config MITIGATION_SPECTRE_BHI 2642 bool "Mitigate Spectre-BHB (Branch History Injection)" 2643 depends on CPU_SUP_INTEL 2644 default y 2645 help 2646 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2647 where the branch history buffer is poisoned to speculatively steer 2648 indirect branches. 2649 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2650 2651config MITIGATION_MDS 2652 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug" 2653 depends on CPU_SUP_INTEL 2654 default y 2655 help 2656 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is 2657 a hardware vulnerability which allows unprivileged speculative access 2658 to data which is available in various CPU internal buffers. 2659 See also <file:Documentation/admin-guide/hw-vuln/mds.rst> 2660 2661config MITIGATION_TAA 2662 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug" 2663 depends on CPU_SUP_INTEL 2664 default y 2665 help 2666 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware 2667 vulnerability that allows unprivileged speculative access to data 2668 which is available in various CPU internal buffers by using 2669 asynchronous aborts within an Intel TSX transactional region. 2670 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst> 2671 2672config MITIGATION_MMIO_STALE_DATA 2673 bool "Mitigate MMIO Stale Data hardware bug" 2674 depends on CPU_SUP_INTEL 2675 default y 2676 help 2677 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO 2678 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO) 2679 vulnerabilities that can expose data. The vulnerabilities require the 2680 attacker to have access to MMIO. 2681 See also 2682 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst> 2683 2684config MITIGATION_L1TF 2685 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug" 2686 depends on CPU_SUP_INTEL 2687 default y 2688 help 2689 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a 2690 hardware vulnerability which allows unprivileged speculative access to data 2691 available in the Level 1 Data Cache. 2692 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst 2693 2694config MITIGATION_RETBLEED 2695 bool "Mitigate RETBleed hardware bug" 2696 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY 2697 default y 2698 help 2699 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution 2700 with Return Instructions) vulnerability. RETBleed is a speculative 2701 execution attack which takes advantage of microarchitectural behavior 2702 in many modern microprocessors, similar to Spectre v2. An 2703 unprivileged attacker can use these flaws to bypass conventional 2704 memory security restrictions to gain read access to privileged memory 2705 that would otherwise be inaccessible. 2706 2707config MITIGATION_SPECTRE_V1 2708 bool "Mitigate SPECTRE V1 hardware bug" 2709 default y 2710 help 2711 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a 2712 class of side channel attacks that takes advantage of speculative 2713 execution that bypasses conditional branch instructions used for 2714 memory access bounds check. 2715 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2716 2717config MITIGATION_SPECTRE_V2 2718 bool "Mitigate SPECTRE V2 hardware bug" 2719 default y 2720 help 2721 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre 2722 V2 is a class of side channel attacks that takes advantage of 2723 indirect branch predictors inside the processor. In Spectre variant 2 2724 attacks, the attacker can steer speculative indirect branches in the 2725 victim to gadget code by poisoning the branch target buffer of a CPU 2726 used for predicting indirect branch addresses. 2727 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2728 2729config MITIGATION_SRBDS 2730 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug" 2731 depends on CPU_SUP_INTEL 2732 default y 2733 help 2734 Enable mitigation for Special Register Buffer Data Sampling (SRBDS). 2735 SRBDS is a hardware vulnerability that allows Microarchitectural Data 2736 Sampling (MDS) techniques to infer values returned from special 2737 register accesses. An unprivileged user can extract values returned 2738 from RDRAND and RDSEED executed on another core or sibling thread 2739 using MDS techniques. 2740 See also 2741 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst> 2742 2743config MITIGATION_SSB 2744 bool "Mitigate Speculative Store Bypass (SSB) hardware bug" 2745 default y 2746 help 2747 Enable mitigation for Speculative Store Bypass (SSB). SSB is a 2748 hardware security vulnerability and its exploitation takes advantage 2749 of speculative execution in a similar way to the Meltdown and Spectre 2750 security vulnerabilities. 2751 2752config MITIGATION_ITS 2753 bool "Enable Indirect Target Selection mitigation" 2754 depends on CPU_SUP_INTEL && X86_64 2755 depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK 2756 select EXECMEM 2757 default y 2758 help 2759 Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in 2760 BPU on some Intel CPUs that may allow Spectre V2 style attacks. If 2761 disabled, mitigation cannot be enabled via cmdline. 2762 See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst> 2763 2764config MITIGATION_TSA 2765 bool "Mitigate Transient Scheduler Attacks" 2766 depends on CPU_SUP_AMD 2767 default y 2768 help 2769 Enable mitigation for Transient Scheduler Attacks. TSA is a hardware 2770 security vulnerability on AMD CPUs which can lead to forwarding of 2771 invalid info to subsequent instructions and thus can affect their 2772 timing and thereby cause a leakage. 2773 2774config MITIGATION_VMSCAPE 2775 bool "Mitigate VMSCAPE" 2776 depends on KVM 2777 default y 2778 help 2779 Enable mitigation for VMSCAPE attacks. VMSCAPE is a hardware security 2780 vulnerability on Intel and AMD CPUs that may allow a guest to do 2781 Spectre v2 style attacks on userspace hypervisor. 2782endif 2783 2784config ARCH_HAS_ADD_PAGES 2785 def_bool y 2786 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2787 2788menu "Power management and ACPI options" 2789 2790config ARCH_HIBERNATION_HEADER 2791 def_bool y 2792 depends on HIBERNATION 2793 2794source "kernel/power/Kconfig" 2795 2796source "drivers/acpi/Kconfig" 2797 2798config X86_APM_BOOT 2799 def_bool y 2800 depends on APM 2801 2802menuconfig APM 2803 tristate "APM (Advanced Power Management) BIOS support" 2804 depends on X86_32 && PM_SLEEP 2805 help 2806 APM is a BIOS specification for saving power using several different 2807 techniques. This is mostly useful for battery powered laptops with 2808 APM compliant BIOSes. If you say Y here, the system time will be 2809 reset after a RESUME operation, the /proc/apm device will provide 2810 battery status information, and user-space programs will receive 2811 notification of APM "events" (e.g. battery status change). 2812 2813 If you select "Y" here, you can disable actual use of the APM 2814 BIOS by passing the "apm=off" option to the kernel at boot time. 2815 2816 Note that the APM support is almost completely disabled for 2817 machines with more than one CPU. 2818 2819 In order to use APM, you will need supporting software. For location 2820 and more information, read <file:Documentation/power/apm-acpi.rst> 2821 and the Battery Powered Linux mini-HOWTO, available from 2822 <http://www.tldp.org/docs.html#howto>. 2823 2824 This driver does not spin down disk drives (see the hdparm(8) 2825 manpage ("man 8 hdparm") for that), and it doesn't turn off 2826 VESA-compliant "green" monitors. 2827 2828 This driver does not support the TI 4000M TravelMate and the ACER 2829 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2830 desktop machines also don't have compliant BIOSes, and this driver 2831 may cause those machines to panic during the boot phase. 2832 2833 Generally, if you don't have a battery in your machine, there isn't 2834 much point in using this driver and you should say N. If you get 2835 random kernel OOPSes or reboots that don't seem to be related to 2836 anything, try disabling/enabling this option (or disabling/enabling 2837 APM in your BIOS). 2838 2839 Some other things you should try when experiencing seemingly random, 2840 "weird" problems: 2841 2842 1) make sure that you have enough swap space and that it is 2843 enabled. 2844 2) pass the "idle=poll" option to the kernel 2845 3) switch on floating point emulation in the kernel and pass 2846 the "no387" option to the kernel 2847 4) pass the "floppy=nodma" option to the kernel 2848 5) pass the "mem=4M" option to the kernel (thereby disabling 2849 all but the first 4 MB of RAM) 2850 6) make sure that the CPU is not over clocked. 2851 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2852 8) disable the cache from your BIOS settings 2853 9) install a fan for the video card or exchange video RAM 2854 10) install a better fan for the CPU 2855 11) exchange RAM chips 2856 12) exchange the motherboard. 2857 2858 To compile this driver as a module, choose M here: the 2859 module will be called apm. 2860 2861if APM 2862 2863config APM_IGNORE_USER_SUSPEND 2864 bool "Ignore USER SUSPEND" 2865 help 2866 This option will ignore USER SUSPEND requests. On machines with a 2867 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2868 series notebooks, it is necessary to say Y because of a BIOS bug. 2869 2870config APM_DO_ENABLE 2871 bool "Enable PM at boot time" 2872 help 2873 Enable APM features at boot time. From page 36 of the APM BIOS 2874 specification: "When disabled, the APM BIOS does not automatically 2875 power manage devices, enter the Standby State, enter the Suspend 2876 State, or take power saving steps in response to CPU Idle calls." 2877 This driver will make CPU Idle calls when Linux is idle (unless this 2878 feature is turned off -- see "Do CPU IDLE calls", below). This 2879 should always save battery power, but more complicated APM features 2880 will be dependent on your BIOS implementation. You may need to turn 2881 this option off if your computer hangs at boot time when using APM 2882 support, or if it beeps continuously instead of suspending. Turn 2883 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2884 T400CDT. This is off by default since most machines do fine without 2885 this feature. 2886 2887config APM_CPU_IDLE 2888 depends on CPU_IDLE 2889 bool "Make CPU Idle calls when idle" 2890 help 2891 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2892 On some machines, this can activate improved power savings, such as 2893 a slowed CPU clock rate, when the machine is idle. These idle calls 2894 are made after the idle loop has run for some length of time (e.g., 2895 333 mS). On some machines, this will cause a hang at boot time or 2896 whenever the CPU becomes idle. (On machines with more than one CPU, 2897 this option does nothing.) 2898 2899config APM_DISPLAY_BLANK 2900 bool "Enable console blanking using APM" 2901 help 2902 Enable console blanking using the APM. Some laptops can use this to 2903 turn off the LCD backlight when the screen blanker of the Linux 2904 virtual console blanks the screen. Note that this is only used by 2905 the virtual console screen blanker, and won't turn off the backlight 2906 when using the X Window system. This also doesn't have anything to 2907 do with your VESA-compliant power-saving monitor. Further, this 2908 option doesn't work for all laptops -- it might not turn off your 2909 backlight at all, or it might print a lot of errors to the console, 2910 especially if you are using gpm. 2911 2912config APM_ALLOW_INTS 2913 bool "Allow interrupts during APM BIOS calls" 2914 help 2915 Normally we disable external interrupts while we are making calls to 2916 the APM BIOS as a measure to lessen the effects of a badly behaving 2917 BIOS implementation. The BIOS should reenable interrupts if it 2918 needs to. Unfortunately, some BIOSes do not -- especially those in 2919 many of the newer IBM Thinkpads. If you experience hangs when you 2920 suspend, try setting this to Y. Otherwise, say N. 2921 2922endif # APM 2923 2924source "drivers/cpufreq/Kconfig" 2925 2926source "drivers/cpuidle/Kconfig" 2927 2928source "drivers/idle/Kconfig" 2929 2930endmenu 2931 2932menu "Bus options (PCI etc.)" 2933 2934choice 2935 prompt "PCI access mode" 2936 depends on X86_32 && PCI 2937 default PCI_GOANY 2938 help 2939 On PCI systems, the BIOS can be used to detect the PCI devices and 2940 determine their configuration. However, some old PCI motherboards 2941 have BIOS bugs and may crash if this is done. Also, some embedded 2942 PCI-based systems don't have any BIOS at all. Linux can also try to 2943 detect the PCI hardware directly without using the BIOS. 2944 2945 With this option, you can specify how Linux should detect the 2946 PCI devices. If you choose "BIOS", the BIOS will be used, 2947 if you choose "Direct", the BIOS won't be used, and if you 2948 choose "MMConfig", then PCI Express MMCONFIG will be used. 2949 If you choose "Any", the kernel will try MMCONFIG, then the 2950 direct access method and falls back to the BIOS if that doesn't 2951 work. If unsure, go with the default, which is "Any". 2952 2953config PCI_GOBIOS 2954 bool "BIOS" 2955 2956config PCI_GOMMCONFIG 2957 bool "MMConfig" 2958 2959config PCI_GODIRECT 2960 bool "Direct" 2961 2962config PCI_GOOLPC 2963 bool "OLPC XO-1" 2964 depends on OLPC 2965 2966config PCI_GOANY 2967 bool "Any" 2968 2969endchoice 2970 2971config PCI_BIOS 2972 def_bool y 2973 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2974 2975# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2976config PCI_DIRECT 2977 def_bool y 2978 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2979 2980config PCI_MMCONFIG 2981 bool "Support mmconfig PCI config space access" if X86_64 2982 default y 2983 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2984 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2985 2986config PCI_OLPC 2987 def_bool y 2988 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2989 2990config PCI_XEN 2991 def_bool y 2992 depends on PCI && XEN 2993 2994config MMCONF_FAM10H 2995 def_bool y 2996 depends on X86_64 && PCI_MMCONFIG && ACPI 2997 2998config PCI_CNB20LE_QUIRK 2999 bool "Read CNB20LE Host Bridge Windows" if EXPERT 3000 depends on PCI 3001 help 3002 Read the PCI windows out of the CNB20LE host bridge. This allows 3003 PCI hotplug to work on systems with the CNB20LE chipset which do 3004 not have ACPI. 3005 3006 There's no public spec for this chipset, and this functionality 3007 is known to be incomplete. 3008 3009 You should say N unless you know you need this. 3010 3011config ISA_BUS 3012 bool "ISA bus support on modern systems" if EXPERT 3013 help 3014 Expose ISA bus device drivers and options available for selection and 3015 configuration. Enable this option if your target machine has an ISA 3016 bus. ISA is an older system, displaced by PCI and newer bus 3017 architectures -- if your target machine is modern, it probably does 3018 not have an ISA bus. 3019 3020 If unsure, say N. 3021 3022# x86_64 have no ISA slots, but can have ISA-style DMA. 3023config ISA_DMA_API 3024 bool "ISA-style DMA support" if (X86_64 && EXPERT) 3025 default y 3026 help 3027 Enables ISA-style DMA support for devices requiring such controllers. 3028 If unsure, say Y. 3029 3030if X86_32 3031 3032config ISA 3033 bool "ISA support" 3034 help 3035 Find out whether you have ISA slots on your motherboard. ISA is the 3036 name of a bus system, i.e. the way the CPU talks to the other stuff 3037 inside your box. Other bus systems are PCI, EISA, MicroChannel 3038 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 3039 newer boards don't support it. If you have ISA, say Y, otherwise N. 3040 3041config SCx200 3042 tristate "NatSemi SCx200 support" 3043 help 3044 This provides basic support for National Semiconductor's 3045 (now AMD's) Geode processors. The driver probes for the 3046 PCI-IDs of several on-chip devices, so its a good dependency 3047 for other scx200_* drivers. 3048 3049 If compiled as a module, the driver is named scx200. 3050 3051config SCx200HR_TIMER 3052 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 3053 depends on SCx200 3054 default y 3055 help 3056 This driver provides a clocksource built upon the on-chip 3057 27MHz high-resolution timer. Its also a workaround for 3058 NSC Geode SC-1100's buggy TSC, which loses time when the 3059 processor goes idle (as is done by the scheduler). The 3060 other workaround is idle=poll boot option. 3061 3062config OLPC 3063 bool "One Laptop Per Child support" 3064 depends on !X86_PAE 3065 select GPIOLIB 3066 select OF 3067 select OF_PROMTREE 3068 select IRQ_DOMAIN 3069 select OLPC_EC 3070 help 3071 Add support for detecting the unique features of the OLPC 3072 XO hardware. 3073 3074config OLPC_XO1_PM 3075 bool "OLPC XO-1 Power Management" 3076 depends on OLPC && MFD_CS5535=y && PM_SLEEP 3077 help 3078 Add support for poweroff and suspend of the OLPC XO-1 laptop. 3079 3080config OLPC_XO1_RTC 3081 bool "OLPC XO-1 Real Time Clock" 3082 depends on OLPC_XO1_PM && RTC_DRV_CMOS 3083 help 3084 Add support for the XO-1 real time clock, which can be used as a 3085 programmable wakeup source. 3086 3087config OLPC_XO1_SCI 3088 bool "OLPC XO-1 SCI extras" 3089 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 3090 depends on INPUT=y 3091 select POWER_SUPPLY 3092 help 3093 Add support for SCI-based features of the OLPC XO-1 laptop: 3094 - EC-driven system wakeups 3095 - Power button 3096 - Ebook switch 3097 - Lid switch 3098 - AC adapter status updates 3099 - Battery status updates 3100 3101config OLPC_XO15_SCI 3102 bool "OLPC XO-1.5 SCI extras" 3103 depends on OLPC && ACPI 3104 select POWER_SUPPLY 3105 help 3106 Add support for SCI-based features of the OLPC XO-1.5 laptop: 3107 - EC-driven system wakeups 3108 - AC adapter status updates 3109 - Battery status updates 3110 3111config GEODE_COMMON 3112 bool 3113 3114config ALIX 3115 bool "PCEngines ALIX System Support (LED setup)" 3116 select GPIOLIB 3117 select GEODE_COMMON 3118 help 3119 This option enables system support for the PCEngines ALIX. 3120 At present this just sets up LEDs for GPIO control on 3121 ALIX2/3/6 boards. However, other system specific setup should 3122 get added here. 3123 3124 Note: You must still enable the drivers for GPIO and LED support 3125 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 3126 3127 Note: You have to set alix.force=1 for boards with Award BIOS. 3128 3129config NET5501 3130 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3131 select GPIOLIB 3132 select GEODE_COMMON 3133 help 3134 This option enables system support for the Soekris Engineering net5501. 3135 3136config GEOS 3137 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3138 select GPIOLIB 3139 select GEODE_COMMON 3140 depends on DMI 3141 help 3142 This option enables system support for the Traverse Technologies GEOS. 3143 3144config TS5500 3145 bool "Technologic Systems TS-5500 platform support" 3146 depends on MELAN 3147 select CHECK_SIGNATURE 3148 select NEW_LEDS 3149 select LEDS_CLASS 3150 help 3151 This option enables system support for the Technologic Systems TS-5500. 3152 3153endif # X86_32 3154 3155config AMD_NB 3156 def_bool y 3157 depends on CPU_SUP_AMD && PCI 3158 3159endmenu 3160 3161menu "Binary Emulations" 3162 3163config IA32_EMULATION 3164 bool "IA32 Emulation" 3165 depends on X86_64 3166 select ARCH_WANT_OLD_COMPAT_IPC 3167 select BINFMT_ELF 3168 select COMPAT_OLD_SIGACTION 3169 help 3170 Include code to run legacy 32-bit programs under a 3171 64-bit kernel. You should likely turn this on, unless you're 3172 100% sure that you don't have any 32-bit programs left. 3173 3174config IA32_EMULATION_DEFAULT_DISABLED 3175 bool "IA32 emulation disabled by default" 3176 default n 3177 depends on IA32_EMULATION 3178 help 3179 Make IA32 emulation disabled by default. This prevents loading 32-bit 3180 processes and access to 32-bit syscalls. If unsure, leave it to its 3181 default value. 3182 3183config X86_X32_ABI 3184 bool "x32 ABI for 64-bit mode" 3185 depends on X86_64 3186 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3187 # compressed debug sections to x86_x32 properly: 3188 # https://github.com/ClangBuiltLinux/linux/issues/514 3189 # https://github.com/ClangBuiltLinux/linux/issues/1141 3190 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3191 help 3192 Include code to run binaries for the x32 native 32-bit ABI 3193 for 64-bit processors. An x32 process gets access to the 3194 full 64-bit register file and wide data path while leaving 3195 pointers at 32 bits for smaller memory footprint. 3196 3197config COMPAT_32 3198 def_bool y 3199 depends on IA32_EMULATION || X86_32 3200 select HAVE_UID16 3201 select OLD_SIGSUSPEND3 3202 3203config COMPAT 3204 def_bool y 3205 depends on IA32_EMULATION || X86_X32_ABI 3206 3207config COMPAT_FOR_U64_ALIGNMENT 3208 def_bool y 3209 depends on COMPAT 3210 3211endmenu 3212 3213config HAVE_ATOMIC_IOMAP 3214 def_bool y 3215 depends on X86_32 3216 3217source "arch/x86/kvm/Kconfig" 3218 3219source "arch/x86/Kconfig.assembler" 3220