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_USE_BUILTIN_BSWAP 130 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64 131 select ARCH_USE_MEMTEST 132 select ARCH_USE_QUEUED_RWLOCKS 133 select ARCH_USE_QUEUED_SPINLOCKS 134 select ARCH_USE_SYM_ANNOTATIONS 135 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 136 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 137 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 138 select ARCH_WANTS_NO_INSTR 139 select ARCH_WANT_GENERAL_HUGETLB 140 select ARCH_WANT_HUGE_PMD_SHARE 141 select ARCH_WANT_LD_ORPHAN_WARN 142 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 143 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 144 select ARCH_WANTS_THP_SWAP if X86_64 145 select ARCH_HAS_PARANOID_L1D_FLUSH 146 select BUILDTIME_TABLE_SORT 147 select CLKEVT_I8253 148 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 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 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 select ARCH_HAS_CC_PLATFORM 899 select X86_MEM_ENCRYPT 900 select X86_MCE 901 select UNACCEPTED_MEMORY 902 help 903 Support running as a guest under Intel TDX. Without this support, 904 the guest kernel can not boot or run under TDX. 905 TDX includes memory encryption and integrity capabilities 906 which protect the confidentiality and integrity of guest 907 memory contents and CPU state. TDX guests are protected from 908 some attacks from the VMM. 909 910endif # HYPERVISOR_GUEST 911 912source "arch/x86/Kconfig.cpu" 913 914config HPET_TIMER 915 def_bool X86_64 916 prompt "HPET Timer Support" if X86_32 917 help 918 Use the IA-PC HPET (High Precision Event Timer) to manage 919 time in preference to the PIT and RTC, if a HPET is 920 present. 921 HPET is the next generation timer replacing legacy 8254s. 922 The HPET provides a stable time base on SMP 923 systems, unlike the TSC, but it is more expensive to access, 924 as it is off-chip. The interface used is documented 925 in the HPET spec, revision 1. 926 927 You can safely choose Y here. However, HPET will only be 928 activated if the platform and the BIOS support this feature. 929 Otherwise the 8254 will be used for timing services. 930 931 Choose N to continue using the legacy 8254 timer. 932 933config HPET_EMULATE_RTC 934 def_bool y 935 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 936 937# Mark as expert because too many people got it wrong. 938# The code disables itself when not needed. 939config DMI 940 default y 941 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 942 bool "Enable DMI scanning" if EXPERT 943 help 944 Enabled scanning of DMI to identify machine quirks. Say Y 945 here unless you have verified that your setup is not 946 affected by entries in the DMI blacklist. Required by PNP 947 BIOS code. 948 949config GART_IOMMU 950 bool "Old AMD GART IOMMU support" 951 select IOMMU_HELPER 952 select SWIOTLB 953 depends on X86_64 && PCI && AMD_NB 954 help 955 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 956 GART based hardware IOMMUs. 957 958 The GART supports full DMA access for devices with 32-bit access 959 limitations, on systems with more than 3 GB. This is usually needed 960 for USB, sound, many IDE/SATA chipsets and some other devices. 961 962 Newer systems typically have a modern AMD IOMMU, supported via 963 the CONFIG_AMD_IOMMU=y config option. 964 965 In normal configurations this driver is only active when needed: 966 there's more than 3 GB of memory and the system contains a 967 32-bit limited device. 968 969 If unsure, say Y. 970 971config BOOT_VESA_SUPPORT 972 bool 973 help 974 If true, at least one selected framebuffer driver can take advantage 975 of VESA video modes set at an early boot stage via the vga= parameter. 976 977config MAXSMP 978 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 979 depends on X86_64 && SMP && DEBUG_KERNEL 980 select CPUMASK_OFFSTACK 981 help 982 Enable maximum number of CPUS and NUMA Nodes for this architecture. 983 If unsure, say N. 984 985# 986# The maximum number of CPUs supported: 987# 988# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 989# and which can be configured interactively in the 990# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 991# 992# The ranges are different on 32-bit and 64-bit kernels, depending on 993# hardware capabilities and scalability features of the kernel. 994# 995# ( If MAXSMP is enabled we just use the highest possible value and disable 996# interactive configuration. ) 997# 998 999config NR_CPUS_RANGE_BEGIN 1000 int 1001 default NR_CPUS_RANGE_END if MAXSMP 1002 default 1 if !SMP 1003 default 2 1004 1005config NR_CPUS_RANGE_END 1006 int 1007 depends on X86_32 1008 default 64 if SMP && X86_BIGSMP 1009 default 8 if SMP && !X86_BIGSMP 1010 default 1 if !SMP 1011 1012config NR_CPUS_RANGE_END 1013 int 1014 depends on X86_64 1015 default 8192 if SMP && CPUMASK_OFFSTACK 1016 default 512 if SMP && !CPUMASK_OFFSTACK 1017 default 1 if !SMP 1018 1019config NR_CPUS_DEFAULT 1020 int 1021 depends on X86_32 1022 default 32 if X86_BIGSMP 1023 default 8 if SMP 1024 default 1 if !SMP 1025 1026config NR_CPUS_DEFAULT 1027 int 1028 depends on X86_64 1029 default 8192 if MAXSMP 1030 default 64 if SMP 1031 default 1 if !SMP 1032 1033config NR_CPUS 1034 int "Maximum number of CPUs" if SMP && !MAXSMP 1035 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1036 default NR_CPUS_DEFAULT 1037 help 1038 This allows you to specify the maximum number of CPUs which this 1039 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1040 supported value is 8192, otherwise the maximum value is 512. The 1041 minimum value which makes sense is 2. 1042 1043 This is purely to save memory: each supported CPU adds about 8KB 1044 to the kernel image. 1045 1046config SCHED_CLUSTER 1047 bool "Cluster scheduler support" 1048 depends on SMP 1049 default y 1050 help 1051 Cluster scheduler support improves the CPU scheduler's decision 1052 making when dealing with machines that have clusters of CPUs. 1053 Cluster usually means a couple of CPUs which are placed closely 1054 by sharing mid-level caches, last-level cache tags or internal 1055 busses. 1056 1057config SCHED_SMT 1058 def_bool y if SMP 1059 1060config SCHED_MC 1061 def_bool y 1062 prompt "Multi-core scheduler support" 1063 depends on SMP 1064 help 1065 Multi-core scheduler support improves the CPU scheduler's decision 1066 making when dealing with multi-core CPU chips at a cost of slightly 1067 increased overhead in some places. If unsure say N here. 1068 1069config SCHED_MC_PRIO 1070 bool "CPU core priorities scheduler support" 1071 depends on SCHED_MC 1072 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1073 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1074 select CPU_FREQ 1075 default y 1076 help 1077 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1078 core ordering determined at manufacturing time, which allows 1079 certain cores to reach higher turbo frequencies (when running 1080 single threaded workloads) than others. 1081 1082 Enabling this kernel feature teaches the scheduler about 1083 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1084 scheduler's CPU selection logic accordingly, so that higher 1085 overall system performance can be achieved. 1086 1087 This feature will have no effect on CPUs without this feature. 1088 1089 If unsure say Y here. 1090 1091config UP_LATE_INIT 1092 def_bool y 1093 depends on !SMP && X86_LOCAL_APIC 1094 1095config X86_UP_APIC 1096 bool "Local APIC support on uniprocessors" if !PCI_MSI 1097 default PCI_MSI 1098 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1099 help 1100 A local APIC (Advanced Programmable Interrupt Controller) is an 1101 integrated interrupt controller in the CPU. If you have a single-CPU 1102 system which has a processor with a local APIC, you can say Y here to 1103 enable and use it. If you say Y here even though your machine doesn't 1104 have a local APIC, then the kernel will still run with no slowdown at 1105 all. The local APIC supports CPU-generated self-interrupts (timer, 1106 performance counters), and the NMI watchdog which detects hard 1107 lockups. 1108 1109config X86_UP_IOAPIC 1110 bool "IO-APIC support on uniprocessors" 1111 depends on X86_UP_APIC 1112 help 1113 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1114 SMP-capable replacement for PC-style interrupt controllers. Most 1115 SMP systems and many recent uniprocessor systems have one. 1116 1117 If you have a single-CPU system with an IO-APIC, you can say Y here 1118 to use it. If you say Y here even though your machine doesn't have 1119 an IO-APIC, then the kernel will still run with no slowdown at all. 1120 1121config X86_LOCAL_APIC 1122 def_bool y 1123 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1124 select IRQ_DOMAIN_HIERARCHY 1125 1126config ACPI_MADT_WAKEUP 1127 def_bool y 1128 depends on X86_64 1129 depends on ACPI 1130 depends on SMP 1131 depends on X86_LOCAL_APIC 1132 1133config X86_IO_APIC 1134 def_bool y 1135 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1136 1137config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1138 bool "Reroute for broken boot IRQs" 1139 depends on X86_IO_APIC 1140 help 1141 This option enables a workaround that fixes a source of 1142 spurious interrupts. This is recommended when threaded 1143 interrupt handling is used on systems where the generation of 1144 superfluous "boot interrupts" cannot be disabled. 1145 1146 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1147 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1148 kernel does during interrupt handling). On chipsets where this 1149 boot IRQ generation cannot be disabled, this workaround keeps 1150 the original IRQ line masked so that only the equivalent "boot 1151 IRQ" is delivered to the CPUs. The workaround also tells the 1152 kernel to set up the IRQ handler on the boot IRQ line. In this 1153 way only one interrupt is delivered to the kernel. Otherwise 1154 the spurious second interrupt may cause the kernel to bring 1155 down (vital) interrupt lines. 1156 1157 Only affects "broken" chipsets. Interrupt sharing may be 1158 increased on these systems. 1159 1160config X86_MCE 1161 bool "Machine Check / overheating reporting" 1162 select GENERIC_ALLOCATOR 1163 default y 1164 help 1165 Machine Check support allows the processor to notify the 1166 kernel if it detects a problem (e.g. overheating, data corruption). 1167 The action the kernel takes depends on the severity of the problem, 1168 ranging from warning messages to halting the machine. 1169 1170config X86_MCELOG_LEGACY 1171 bool "Support for deprecated /dev/mcelog character device" 1172 depends on X86_MCE 1173 help 1174 Enable support for /dev/mcelog which is needed by the old mcelog 1175 userspace logging daemon. Consider switching to the new generation 1176 rasdaemon solution. 1177 1178config X86_MCE_INTEL 1179 def_bool y 1180 prompt "Intel MCE features" 1181 depends on X86_MCE && X86_LOCAL_APIC 1182 help 1183 Additional support for intel specific MCE features such as 1184 the thermal monitor. 1185 1186config X86_MCE_AMD 1187 def_bool y 1188 prompt "AMD MCE features" 1189 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1190 help 1191 Additional support for AMD specific MCE features such as 1192 the DRAM Error Threshold. 1193 1194config X86_ANCIENT_MCE 1195 bool "Support for old Pentium 5 / WinChip machine checks" 1196 depends on X86_32 && X86_MCE 1197 help 1198 Include support for machine check handling on old Pentium 5 or WinChip 1199 systems. These typically need to be enabled explicitly on the command 1200 line. 1201 1202config X86_MCE_THRESHOLD 1203 depends on X86_MCE_AMD || X86_MCE_INTEL 1204 def_bool y 1205 1206config X86_MCE_INJECT 1207 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1208 tristate "Machine check injector support" 1209 help 1210 Provide support for injecting machine checks for testing purposes. 1211 If you don't know what a machine check is and you don't do kernel 1212 QA it is safe to say n. 1213 1214source "arch/x86/events/Kconfig" 1215 1216config X86_LEGACY_VM86 1217 bool "Legacy VM86 support" 1218 depends on X86_32 1219 help 1220 This option allows user programs to put the CPU into V8086 1221 mode, which is an 80286-era approximation of 16-bit real mode. 1222 1223 Some very old versions of X and/or vbetool require this option 1224 for user mode setting. Similarly, DOSEMU will use it if 1225 available to accelerate real mode DOS programs. However, any 1226 recent version of DOSEMU, X, or vbetool should be fully 1227 functional even without kernel VM86 support, as they will all 1228 fall back to software emulation. Nevertheless, if you are using 1229 a 16-bit DOS program where 16-bit performance matters, vm86 1230 mode might be faster than emulation and you might want to 1231 enable this option. 1232 1233 Note that any app that works on a 64-bit kernel is unlikely to 1234 need this option, as 64-bit kernels don't, and can't, support 1235 V8086 mode. This option is also unrelated to 16-bit protected 1236 mode and is not needed to run most 16-bit programs under Wine. 1237 1238 Enabling this option increases the complexity of the kernel 1239 and slows down exception handling a tiny bit. 1240 1241 If unsure, say N here. 1242 1243config VM86 1244 bool 1245 default X86_LEGACY_VM86 1246 1247config X86_16BIT 1248 bool "Enable support for 16-bit segments" if EXPERT 1249 default y 1250 depends on MODIFY_LDT_SYSCALL 1251 help 1252 This option is required by programs like Wine to run 16-bit 1253 protected mode legacy code on x86 processors. Disabling 1254 this option saves about 300 bytes on i386, or around 6K text 1255 plus 16K runtime memory on x86-64, 1256 1257config X86_ESPFIX32 1258 def_bool y 1259 depends on X86_16BIT && X86_32 1260 1261config X86_ESPFIX64 1262 def_bool y 1263 depends on X86_16BIT && X86_64 1264 1265config X86_VSYSCALL_EMULATION 1266 bool "Enable vsyscall emulation" if EXPERT 1267 default y 1268 depends on X86_64 1269 help 1270 This enables emulation of the legacy vsyscall page. Disabling 1271 it is roughly equivalent to booting with vsyscall=none, except 1272 that it will also disable the helpful warning if a program 1273 tries to use a vsyscall. With this option set to N, offending 1274 programs will just segfault, citing addresses of the form 1275 0xffffffffff600?00. 1276 1277 This option is required by many programs built before 2013, and 1278 care should be used even with newer programs if set to N. 1279 1280 Disabling this option saves about 7K of kernel size and 1281 possibly 4K of additional runtime pagetable memory. 1282 1283config X86_IOPL_IOPERM 1284 bool "IOPERM and IOPL Emulation" 1285 default y 1286 help 1287 This enables the ioperm() and iopl() syscalls which are necessary 1288 for legacy applications. 1289 1290 Legacy IOPL support is an overbroad mechanism which allows user 1291 space aside of accessing all 65536 I/O ports also to disable 1292 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1293 capabilities and permission from potentially active security 1294 modules. 1295 1296 The emulation restricts the functionality of the syscall to 1297 only allowing the full range I/O port access, but prevents the 1298 ability to disable interrupts from user space which would be 1299 granted if the hardware IOPL mechanism would be used. 1300 1301config TOSHIBA 1302 tristate "Toshiba Laptop support" 1303 depends on X86_32 1304 help 1305 This adds a driver to safely access the System Management Mode of 1306 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1307 not work on models with a Phoenix BIOS. The System Management Mode 1308 is used to set the BIOS and power saving options on Toshiba portables. 1309 1310 For information on utilities to make use of this driver see the 1311 Toshiba Linux utilities web site at: 1312 <http://www.buzzard.org.uk/toshiba/>. 1313 1314 Say Y if you intend to run this kernel on a Toshiba portable. 1315 Say N otherwise. 1316 1317config X86_REBOOTFIXUPS 1318 bool "Enable X86 board specific fixups for reboot" 1319 depends on X86_32 1320 help 1321 This enables chipset and/or board specific fixups to be done 1322 in order to get reboot to work correctly. This is only needed on 1323 some combinations of hardware and BIOS. The symptom, for which 1324 this config is intended, is when reboot ends with a stalled/hung 1325 system. 1326 1327 Currently, the only fixup is for the Geode machines using 1328 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1329 1330 Say Y if you want to enable the fixup. Currently, it's safe to 1331 enable this option even if you don't need it. 1332 Say N otherwise. 1333 1334config MICROCODE 1335 def_bool y 1336 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1337 1338config MICROCODE_INITRD32 1339 def_bool y 1340 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1341 1342config MICROCODE_LATE_LOADING 1343 bool "Late microcode loading (DANGEROUS)" 1344 default n 1345 depends on MICROCODE && SMP 1346 help 1347 Loading microcode late, when the system is up and executing instructions 1348 is a tricky business and should be avoided if possible. Just the sequence 1349 of synchronizing all cores and SMT threads is one fragile dance which does 1350 not guarantee that cores might not softlock after the loading. Therefore, 1351 use this at your own risk. Late loading taints the kernel unless the 1352 microcode header indicates that it is safe for late loading via the 1353 minimal revision check. This minimal revision check can be enforced on 1354 the kernel command line with "microcode.minrev=Y". 1355 1356config MICROCODE_LATE_FORCE_MINREV 1357 bool "Enforce late microcode loading minimal revision check" 1358 default n 1359 depends on MICROCODE_LATE_LOADING 1360 help 1361 To prevent that users load microcode late which modifies already 1362 in use features, newer microcode patches have a minimum revision field 1363 in the microcode header, which tells the kernel which minimum 1364 revision must be active in the CPU to safely load that new microcode 1365 late into the running system. If disabled the check will not 1366 be enforced but the kernel will be tainted when the minimal 1367 revision check fails. 1368 1369 This minimal revision check can also be controlled via the 1370 "microcode.minrev" parameter on the kernel command line. 1371 1372 If unsure say Y. 1373 1374config X86_MSR 1375 tristate "/dev/cpu/*/msr - Model-specific register support" 1376 help 1377 This device gives privileged processes access to the x86 1378 Model-Specific Registers (MSRs). It is a character device with 1379 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1380 MSR accesses are directed to a specific CPU on multi-processor 1381 systems. 1382 1383config X86_CPUID 1384 tristate "/dev/cpu/*/cpuid - CPU information support" 1385 help 1386 This device gives processes access to the x86 CPUID instruction to 1387 be executed on a specific processor. It is a character device 1388 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1389 /dev/cpu/31/cpuid. 1390 1391choice 1392 prompt "High Memory Support" 1393 default HIGHMEM4G 1394 depends on X86_32 1395 1396config NOHIGHMEM 1397 bool "off" 1398 help 1399 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1400 However, the address space of 32-bit x86 processors is only 4 1401 Gigabytes large. That means that, if you have a large amount of 1402 physical memory, not all of it can be "permanently mapped" by the 1403 kernel. The physical memory that's not permanently mapped is called 1404 "high memory". 1405 1406 If you are compiling a kernel which will never run on a machine with 1407 more than 1 Gigabyte total physical RAM, answer "off" here (default 1408 choice and suitable for most users). This will result in a "3GB/1GB" 1409 split: 3GB are mapped so that each process sees a 3GB virtual memory 1410 space and the remaining part of the 4GB virtual memory space is used 1411 by the kernel to permanently map as much physical memory as 1412 possible. 1413 1414 If the machine has between 1 and 4 Gigabytes physical RAM, then 1415 answer "4GB" here. 1416 1417 If more than 4 Gigabytes is used then answer "64GB" here. This 1418 selection turns Intel PAE (Physical Address Extension) mode on. 1419 PAE implements 3-level paging on IA32 processors. PAE is fully 1420 supported by Linux, PAE mode is implemented on all recent Intel 1421 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1422 then the kernel will not boot on CPUs that don't support PAE! 1423 1424 The actual amount of total physical memory will either be 1425 auto detected or can be forced by using a kernel command line option 1426 such as "mem=256M". (Try "man bootparam" or see the documentation of 1427 your boot loader (lilo or loadlin) about how to pass options to the 1428 kernel at boot time.) 1429 1430 If unsure, say "off". 1431 1432config HIGHMEM4G 1433 bool "4GB" 1434 help 1435 Select this if you have a 32-bit processor and between 1 and 4 1436 gigabytes of physical RAM. 1437 1438config HIGHMEM64G 1439 bool "64GB" 1440 depends on X86_HAVE_PAE 1441 select X86_PAE 1442 help 1443 Select this if you have a 32-bit processor and more than 4 1444 gigabytes of physical RAM. 1445 1446endchoice 1447 1448choice 1449 prompt "Memory split" if EXPERT 1450 default VMSPLIT_3G 1451 depends on X86_32 1452 help 1453 Select the desired split between kernel and user memory. 1454 1455 If the address range available to the kernel is less than the 1456 physical memory installed, the remaining memory will be available 1457 as "high memory". Accessing high memory is a little more costly 1458 than low memory, as it needs to be mapped into the kernel first. 1459 Note that increasing the kernel address space limits the range 1460 available to user programs, making the address space there 1461 tighter. Selecting anything other than the default 3G/1G split 1462 will also likely make your kernel incompatible with binary-only 1463 kernel modules. 1464 1465 If you are not absolutely sure what you are doing, leave this 1466 option alone! 1467 1468 config VMSPLIT_3G 1469 bool "3G/1G user/kernel split" 1470 config VMSPLIT_3G_OPT 1471 depends on !X86_PAE 1472 bool "3G/1G user/kernel split (for full 1G low memory)" 1473 config VMSPLIT_2G 1474 bool "2G/2G user/kernel split" 1475 config VMSPLIT_2G_OPT 1476 depends on !X86_PAE 1477 bool "2G/2G user/kernel split (for full 2G low memory)" 1478 config VMSPLIT_1G 1479 bool "1G/3G user/kernel split" 1480endchoice 1481 1482config PAGE_OFFSET 1483 hex 1484 default 0xB0000000 if VMSPLIT_3G_OPT 1485 default 0x80000000 if VMSPLIT_2G 1486 default 0x78000000 if VMSPLIT_2G_OPT 1487 default 0x40000000 if VMSPLIT_1G 1488 default 0xC0000000 1489 depends on X86_32 1490 1491config HIGHMEM 1492 def_bool y 1493 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1494 1495config X86_PAE 1496 bool "PAE (Physical Address Extension) Support" 1497 depends on X86_32 && X86_HAVE_PAE 1498 select PHYS_ADDR_T_64BIT 1499 select SWIOTLB 1500 help 1501 PAE is required for NX support, and furthermore enables 1502 larger swapspace support for non-overcommit purposes. It 1503 has the cost of more pagetable lookup overhead, and also 1504 consumes more pagetable space per process. 1505 1506config X86_5LEVEL 1507 bool "Enable 5-level page tables support" 1508 default y 1509 select DYNAMIC_MEMORY_LAYOUT 1510 select SPARSEMEM_VMEMMAP 1511 depends on X86_64 1512 help 1513 5-level paging enables access to larger address space: 1514 up to 128 PiB of virtual address space and 4 PiB of 1515 physical address space. 1516 1517 It will be supported by future Intel CPUs. 1518 1519 A kernel with the option enabled can be booted on machines that 1520 support 4- or 5-level paging. 1521 1522 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1523 information. 1524 1525 Say N if unsure. 1526 1527config X86_DIRECT_GBPAGES 1528 def_bool y 1529 depends on X86_64 1530 help 1531 Certain kernel features effectively disable kernel 1532 linear 1 GB mappings (even if the CPU otherwise 1533 supports them), so don't confuse the user by printing 1534 that we have them enabled. 1535 1536config X86_CPA_STATISTICS 1537 bool "Enable statistic for Change Page Attribute" 1538 depends on DEBUG_FS 1539 help 1540 Expose statistics about the Change Page Attribute mechanism, which 1541 helps to determine the effectiveness of preserving large and huge 1542 page mappings when mapping protections are changed. 1543 1544config X86_MEM_ENCRYPT 1545 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1546 select DYNAMIC_PHYSICAL_MASK 1547 def_bool n 1548 1549config AMD_MEM_ENCRYPT 1550 bool "AMD Secure Memory Encryption (SME) support" 1551 depends on X86_64 && CPU_SUP_AMD 1552 depends on EFI_STUB 1553 select DMA_COHERENT_POOL 1554 select ARCH_USE_MEMREMAP_PROT 1555 select INSTRUCTION_DECODER 1556 select ARCH_HAS_CC_PLATFORM 1557 select X86_MEM_ENCRYPT 1558 select UNACCEPTED_MEMORY 1559 help 1560 Say yes to enable support for the encryption of system memory. 1561 This requires an AMD processor that supports Secure Memory 1562 Encryption (SME). 1563 1564# Common NUMA Features 1565config NUMA 1566 bool "NUMA Memory Allocation and Scheduler Support" 1567 depends on SMP 1568 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1569 default y if X86_BIGSMP 1570 select USE_PERCPU_NUMA_NODE_ID 1571 select OF_NUMA if OF 1572 help 1573 Enable NUMA (Non-Uniform Memory Access) support. 1574 1575 The kernel will try to allocate memory used by a CPU on the 1576 local memory controller of the CPU and add some more 1577 NUMA awareness to the kernel. 1578 1579 For 64-bit this is recommended if the system is Intel Core i7 1580 (or later), AMD Opteron, or EM64T NUMA. 1581 1582 For 32-bit this is only needed if you boot a 32-bit 1583 kernel on a 64-bit NUMA platform. 1584 1585 Otherwise, you should say N. 1586 1587config AMD_NUMA 1588 def_bool y 1589 prompt "Old style AMD Opteron NUMA detection" 1590 depends on X86_64 && NUMA && PCI 1591 help 1592 Enable AMD NUMA node topology detection. You should say Y here if 1593 you have a multi processor AMD system. This uses an old method to 1594 read the NUMA configuration directly from the builtin Northbridge 1595 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1596 which also takes priority if both are compiled in. 1597 1598config X86_64_ACPI_NUMA 1599 def_bool y 1600 prompt "ACPI NUMA detection" 1601 depends on X86_64 && NUMA && ACPI && PCI 1602 select ACPI_NUMA 1603 help 1604 Enable ACPI SRAT based node topology detection. 1605 1606config NODES_SHIFT 1607 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1608 range 1 10 1609 default "10" if MAXSMP 1610 default "6" if X86_64 1611 default "3" 1612 depends on NUMA 1613 help 1614 Specify the maximum number of NUMA Nodes available on the target 1615 system. Increases memory reserved to accommodate various tables. 1616 1617config ARCH_FLATMEM_ENABLE 1618 def_bool y 1619 depends on X86_32 && !NUMA 1620 1621config ARCH_SPARSEMEM_ENABLE 1622 def_bool y 1623 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1624 select SPARSEMEM_STATIC if X86_32 1625 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1626 1627config ARCH_SPARSEMEM_DEFAULT 1628 def_bool X86_64 || (NUMA && X86_32) 1629 1630config ARCH_SELECT_MEMORY_MODEL 1631 def_bool y 1632 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1633 1634config ARCH_MEMORY_PROBE 1635 bool "Enable sysfs memory/probe interface" 1636 depends on MEMORY_HOTPLUG 1637 help 1638 This option enables a sysfs memory/probe interface for testing. 1639 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1640 If you are unsure how to answer this question, answer N. 1641 1642config ARCH_PROC_KCORE_TEXT 1643 def_bool y 1644 depends on X86_64 && PROC_KCORE 1645 1646config ILLEGAL_POINTER_VALUE 1647 hex 1648 default 0 if X86_32 1649 default 0xdead000000000000 if X86_64 1650 1651config X86_PMEM_LEGACY_DEVICE 1652 bool 1653 1654config X86_PMEM_LEGACY 1655 tristate "Support non-standard NVDIMMs and ADR protected memory" 1656 depends on PHYS_ADDR_T_64BIT 1657 depends on BLK_DEV 1658 select X86_PMEM_LEGACY_DEVICE 1659 select NUMA_KEEP_MEMINFO if NUMA 1660 select LIBNVDIMM 1661 help 1662 Treat memory marked using the non-standard e820 type of 12 as used 1663 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1664 The kernel will offer these regions to the 'pmem' driver so 1665 they can be used for persistent storage. 1666 1667 Say Y if unsure. 1668 1669config HIGHPTE 1670 bool "Allocate 3rd-level pagetables from highmem" 1671 depends on HIGHMEM 1672 help 1673 The VM uses one page table entry for each page of physical memory. 1674 For systems with a lot of RAM, this can be wasteful of precious 1675 low memory. Setting this option will put user-space page table 1676 entries in high memory. 1677 1678config X86_CHECK_BIOS_CORRUPTION 1679 bool "Check for low memory corruption" 1680 help 1681 Periodically check for memory corruption in low memory, which 1682 is suspected to be caused by BIOS. Even when enabled in the 1683 configuration, it is disabled at runtime. Enable it by 1684 setting "memory_corruption_check=1" on the kernel command 1685 line. By default it scans the low 64k of memory every 60 1686 seconds; see the memory_corruption_check_size and 1687 memory_corruption_check_period parameters in 1688 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1689 1690 When enabled with the default parameters, this option has 1691 almost no overhead, as it reserves a relatively small amount 1692 of memory and scans it infrequently. It both detects corruption 1693 and prevents it from affecting the running system. 1694 1695 It is, however, intended as a diagnostic tool; if repeatable 1696 BIOS-originated corruption always affects the same memory, 1697 you can use memmap= to prevent the kernel from using that 1698 memory. 1699 1700config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1701 bool "Set the default setting of memory_corruption_check" 1702 depends on X86_CHECK_BIOS_CORRUPTION 1703 default y 1704 help 1705 Set whether the default state of memory_corruption_check is 1706 on or off. 1707 1708config MATH_EMULATION 1709 bool 1710 depends on MODIFY_LDT_SYSCALL 1711 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1712 help 1713 Linux can emulate a math coprocessor (used for floating point 1714 operations) if you don't have one. 486DX and Pentium processors have 1715 a math coprocessor built in, 486SX and 386 do not, unless you added 1716 a 487DX or 387, respectively. (The messages during boot time can 1717 give you some hints here ["man dmesg"].) Everyone needs either a 1718 coprocessor or this emulation. 1719 1720 If you don't have a math coprocessor, you need to say Y here; if you 1721 say Y here even though you have a coprocessor, the coprocessor will 1722 be used nevertheless. (This behavior can be changed with the kernel 1723 command line option "no387", which comes handy if your coprocessor 1724 is broken. Try "man bootparam" or see the documentation of your boot 1725 loader (lilo or loadlin) about how to pass options to the kernel at 1726 boot time.) This means that it is a good idea to say Y here if you 1727 intend to use this kernel on different machines. 1728 1729 More information about the internals of the Linux math coprocessor 1730 emulation can be found in <file:arch/x86/math-emu/README>. 1731 1732 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1733 kernel, it won't hurt. 1734 1735config MTRR 1736 def_bool y 1737 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1738 help 1739 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1740 the Memory Type Range Registers (MTRRs) may be used to control 1741 processor access to memory ranges. This is most useful if you have 1742 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1743 allows bus write transfers to be combined into a larger transfer 1744 before bursting over the PCI/AGP bus. This can increase performance 1745 of image write operations 2.5 times or more. Saying Y here creates a 1746 /proc/mtrr file which may be used to manipulate your processor's 1747 MTRRs. Typically the X server should use this. 1748 1749 This code has a reasonably generic interface so that similar 1750 control registers on other processors can be easily supported 1751 as well: 1752 1753 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1754 Registers (ARRs) which provide a similar functionality to MTRRs. For 1755 these, the ARRs are used to emulate the MTRRs. 1756 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1757 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1758 write-combining. All of these processors are supported by this code 1759 and it makes sense to say Y here if you have one of them. 1760 1761 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1762 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1763 can lead to all sorts of problems, so it's good to say Y here. 1764 1765 You can safely say Y even if your machine doesn't have MTRRs, you'll 1766 just add about 9 KB to your kernel. 1767 1768 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1769 1770config MTRR_SANITIZER 1771 def_bool y 1772 prompt "MTRR cleanup support" 1773 depends on MTRR 1774 help 1775 Convert MTRR layout from continuous to discrete, so X drivers can 1776 add writeback entries. 1777 1778 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1779 The largest mtrr entry size for a continuous block can be set with 1780 mtrr_chunk_size. 1781 1782 If unsure, say Y. 1783 1784config MTRR_SANITIZER_ENABLE_DEFAULT 1785 int "MTRR cleanup enable value (0-1)" 1786 range 0 1 1787 default "0" 1788 depends on MTRR_SANITIZER 1789 help 1790 Enable mtrr cleanup default value 1791 1792config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1793 int "MTRR cleanup spare reg num (0-7)" 1794 range 0 7 1795 default "1" 1796 depends on MTRR_SANITIZER 1797 help 1798 mtrr cleanup spare entries default, it can be changed via 1799 mtrr_spare_reg_nr=N on the kernel command line. 1800 1801config X86_PAT 1802 def_bool y 1803 prompt "x86 PAT support" if EXPERT 1804 depends on MTRR 1805 select ARCH_USES_PG_ARCH_2 1806 help 1807 Use PAT attributes to setup page level cache control. 1808 1809 PATs are the modern equivalents of MTRRs and are much more 1810 flexible than MTRRs. 1811 1812 Say N here if you see bootup problems (boot crash, boot hang, 1813 spontaneous reboots) or a non-working video driver. 1814 1815 If unsure, say Y. 1816 1817config X86_UMIP 1818 def_bool y 1819 prompt "User Mode Instruction Prevention" if EXPERT 1820 help 1821 User Mode Instruction Prevention (UMIP) is a security feature in 1822 some x86 processors. If enabled, a general protection fault is 1823 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1824 executed in user mode. These instructions unnecessarily expose 1825 information about the hardware state. 1826 1827 The vast majority of applications do not use these instructions. 1828 For the very few that do, software emulation is provided in 1829 specific cases in protected and virtual-8086 modes. Emulated 1830 results are dummy. 1831 1832config CC_HAS_IBT 1833 # GCC >= 9 and binutils >= 2.29 1834 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1835 # Clang/LLVM >= 14 1836 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1837 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1838 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1839 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1840 $(as-instr,endbr64) 1841 1842config X86_CET 1843 def_bool n 1844 help 1845 CET features configured (Shadow stack or IBT) 1846 1847config X86_KERNEL_IBT 1848 prompt "Indirect Branch Tracking" 1849 def_bool y 1850 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1851 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1852 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1853 select OBJTOOL 1854 select X86_CET 1855 help 1856 Build the kernel with support for Indirect Branch Tracking, a 1857 hardware support course-grain forward-edge Control Flow Integrity 1858 protection. It enforces that all indirect calls must land on 1859 an ENDBR instruction, as such, the compiler will instrument the 1860 code with them to make this happen. 1861 1862 In addition to building the kernel with IBT, seal all functions that 1863 are not indirect call targets, avoiding them ever becoming one. 1864 1865 This requires LTO like objtool runs and will slow down the build. It 1866 does significantly reduce the number of ENDBR instructions in the 1867 kernel image. 1868 1869config X86_INTEL_MEMORY_PROTECTION_KEYS 1870 prompt "Memory Protection Keys" 1871 def_bool y 1872 # Note: only available in 64-bit mode 1873 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1874 select ARCH_USES_HIGH_VMA_FLAGS 1875 select ARCH_HAS_PKEYS 1876 help 1877 Memory Protection Keys provides a mechanism for enforcing 1878 page-based protections, but without requiring modification of the 1879 page tables when an application changes protection domains. 1880 1881 For details, see Documentation/core-api/protection-keys.rst 1882 1883 If unsure, say y. 1884 1885config ARCH_PKEY_BITS 1886 int 1887 default 4 1888 1889choice 1890 prompt "TSX enable mode" 1891 depends on CPU_SUP_INTEL 1892 default X86_INTEL_TSX_MODE_OFF 1893 help 1894 Intel's TSX (Transactional Synchronization Extensions) feature 1895 allows to optimize locking protocols through lock elision which 1896 can lead to a noticeable performance boost. 1897 1898 On the other hand it has been shown that TSX can be exploited 1899 to form side channel attacks (e.g. TAA) and chances are there 1900 will be more of those attacks discovered in the future. 1901 1902 Therefore TSX is not enabled by default (aka tsx=off). An admin 1903 might override this decision by tsx=on the command line parameter. 1904 Even with TSX enabled, the kernel will attempt to enable the best 1905 possible TAA mitigation setting depending on the microcode available 1906 for the particular machine. 1907 1908 This option allows to set the default tsx mode between tsx=on, =off 1909 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1910 details. 1911 1912 Say off if not sure, auto if TSX is in use but it should be used on safe 1913 platforms or on if TSX is in use and the security aspect of tsx is not 1914 relevant. 1915 1916config X86_INTEL_TSX_MODE_OFF 1917 bool "off" 1918 help 1919 TSX is disabled if possible - equals to tsx=off command line parameter. 1920 1921config X86_INTEL_TSX_MODE_ON 1922 bool "on" 1923 help 1924 TSX is always enabled on TSX capable HW - equals the tsx=on command 1925 line parameter. 1926 1927config X86_INTEL_TSX_MODE_AUTO 1928 bool "auto" 1929 help 1930 TSX is enabled on TSX capable HW that is believed to be safe against 1931 side channel attacks- equals the tsx=auto command line parameter. 1932endchoice 1933 1934config X86_SGX 1935 bool "Software Guard eXtensions (SGX)" 1936 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1937 depends on CRYPTO=y 1938 depends on CRYPTO_SHA256=y 1939 select MMU_NOTIFIER 1940 select NUMA_KEEP_MEMINFO if NUMA 1941 select XARRAY_MULTI 1942 help 1943 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1944 that can be used by applications to set aside private regions of code 1945 and data, referred to as enclaves. An enclave's private memory can 1946 only be accessed by code running within the enclave. Accesses from 1947 outside the enclave, including other enclaves, are disallowed by 1948 hardware. 1949 1950 If unsure, say N. 1951 1952config X86_USER_SHADOW_STACK 1953 bool "X86 userspace shadow stack" 1954 depends on AS_WRUSS 1955 depends on X86_64 1956 select ARCH_USES_HIGH_VMA_FLAGS 1957 select ARCH_HAS_USER_SHADOW_STACK 1958 select X86_CET 1959 help 1960 Shadow stack protection is a hardware feature that detects function 1961 return address corruption. This helps mitigate ROP attacks. 1962 Applications must be enabled to use it, and old userspace does not 1963 get protection "for free". 1964 1965 CPUs supporting shadow stacks were first released in 2020. 1966 1967 See Documentation/arch/x86/shstk.rst for more information. 1968 1969 If unsure, say N. 1970 1971config INTEL_TDX_HOST 1972 bool "Intel Trust Domain Extensions (TDX) host support" 1973 depends on CPU_SUP_INTEL 1974 depends on X86_64 1975 depends on KVM_INTEL 1976 depends on X86_X2APIC 1977 select ARCH_KEEP_MEMBLOCK 1978 depends on CONTIG_ALLOC 1979 depends on !KEXEC_CORE 1980 depends on X86_MCE 1981 help 1982 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1983 host and certain physical attacks. This option enables necessary TDX 1984 support in the host kernel to run confidential VMs. 1985 1986 If unsure, say N. 1987 1988config EFI 1989 bool "EFI runtime service support" 1990 depends on ACPI 1991 select UCS2_STRING 1992 select EFI_RUNTIME_WRAPPERS 1993 select ARCH_USE_MEMREMAP_PROT 1994 select EFI_RUNTIME_MAP if KEXEC_CORE 1995 help 1996 This enables the kernel to use EFI runtime services that are 1997 available (such as the EFI variable services). 1998 1999 This option is only useful on systems that have EFI firmware. 2000 In addition, you should use the latest ELILO loader available 2001 at <http://elilo.sourceforge.net> in order to take advantage 2002 of EFI runtime services. However, even with this option, the 2003 resultant kernel should continue to boot on existing non-EFI 2004 platforms. 2005 2006config EFI_STUB 2007 bool "EFI stub support" 2008 depends on EFI 2009 select RELOCATABLE 2010 help 2011 This kernel feature allows a bzImage to be loaded directly 2012 by EFI firmware without the use of a bootloader. 2013 2014 See Documentation/admin-guide/efi-stub.rst for more information. 2015 2016config EFI_HANDOVER_PROTOCOL 2017 bool "EFI handover protocol (DEPRECATED)" 2018 depends on EFI_STUB 2019 default y 2020 help 2021 Select this in order to include support for the deprecated EFI 2022 handover protocol, which defines alternative entry points into the 2023 EFI stub. This is a practice that has no basis in the UEFI 2024 specification, and requires a priori knowledge on the part of the 2025 bootloader about Linux/x86 specific ways of passing the command line 2026 and initrd, and where in memory those assets may be loaded. 2027 2028 If in doubt, say Y. Even though the corresponding support is not 2029 present in upstream GRUB or other bootloaders, most distros build 2030 GRUB with numerous downstream patches applied, and may rely on the 2031 handover protocol as as result. 2032 2033config EFI_MIXED 2034 bool "EFI mixed-mode support" 2035 depends on EFI_STUB && X86_64 2036 help 2037 Enabling this feature allows a 64-bit kernel to be booted 2038 on a 32-bit firmware, provided that your CPU supports 64-bit 2039 mode. 2040 2041 Note that it is not possible to boot a mixed-mode enabled 2042 kernel via the EFI boot stub - a bootloader that supports 2043 the EFI handover protocol must be used. 2044 2045 If unsure, say N. 2046 2047config EFI_RUNTIME_MAP 2048 bool "Export EFI runtime maps to sysfs" if EXPERT 2049 depends on EFI 2050 help 2051 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2052 That memory map is required by the 2nd kernel to set up EFI virtual 2053 mappings after kexec, but can also be used for debugging purposes. 2054 2055 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2056 2057source "kernel/Kconfig.hz" 2058 2059config ARCH_SUPPORTS_KEXEC 2060 def_bool y 2061 2062config ARCH_SUPPORTS_KEXEC_FILE 2063 def_bool X86_64 2064 2065config ARCH_SELECTS_KEXEC_FILE 2066 def_bool y 2067 depends on KEXEC_FILE 2068 select HAVE_IMA_KEXEC if IMA 2069 2070config ARCH_SUPPORTS_KEXEC_PURGATORY 2071 def_bool y 2072 2073config ARCH_SUPPORTS_KEXEC_SIG 2074 def_bool y 2075 2076config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2077 def_bool y 2078 2079config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2080 def_bool y 2081 2082config ARCH_SUPPORTS_KEXEC_JUMP 2083 def_bool y 2084 2085config ARCH_SUPPORTS_CRASH_DUMP 2086 def_bool X86_64 || (X86_32 && HIGHMEM) 2087 2088config ARCH_DEFAULT_CRASH_DUMP 2089 def_bool y 2090 2091config ARCH_SUPPORTS_CRASH_HOTPLUG 2092 def_bool y 2093 2094config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2095 def_bool CRASH_RESERVE 2096 2097config PHYSICAL_START 2098 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2099 default "0x1000000" 2100 help 2101 This gives the physical address where the kernel is loaded. 2102 2103 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2104 will decompress itself to above physical address and run from there. 2105 Otherwise, bzImage will run from the address where it has been loaded 2106 by the boot loader. The only exception is if it is loaded below the 2107 above physical address, in which case it will relocate itself there. 2108 2109 In normal kdump cases one does not have to set/change this option 2110 as now bzImage can be compiled as a completely relocatable image 2111 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2112 address. This option is mainly useful for the folks who don't want 2113 to use a bzImage for capturing the crash dump and want to use a 2114 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2115 to be specifically compiled to run from a specific memory area 2116 (normally a reserved region) and this option comes handy. 2117 2118 So if you are using bzImage for capturing the crash dump, 2119 leave the value here unchanged to 0x1000000 and set 2120 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2121 for capturing the crash dump change this value to start of 2122 the reserved region. In other words, it can be set based on 2123 the "X" value as specified in the "crashkernel=YM@XM" 2124 command line boot parameter passed to the panic-ed 2125 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2126 for more details about crash dumps. 2127 2128 Usage of bzImage for capturing the crash dump is recommended as 2129 one does not have to build two kernels. Same kernel can be used 2130 as production kernel and capture kernel. Above option should have 2131 gone away after relocatable bzImage support is introduced. But it 2132 is present because there are users out there who continue to use 2133 vmlinux for dump capture. This option should go away down the 2134 line. 2135 2136 Don't change this unless you know what you are doing. 2137 2138config RELOCATABLE 2139 bool "Build a relocatable kernel" 2140 default y 2141 help 2142 This builds a kernel image that retains relocation information 2143 so it can be loaded someplace besides the default 1MB. 2144 The relocations tend to make the kernel binary about 10% larger, 2145 but are discarded at runtime. 2146 2147 One use is for the kexec on panic case where the recovery kernel 2148 must live at a different physical address than the primary 2149 kernel. 2150 2151 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2152 it has been loaded at and the compile time physical address 2153 (CONFIG_PHYSICAL_START) is used as the minimum location. 2154 2155config RANDOMIZE_BASE 2156 bool "Randomize the address of the kernel image (KASLR)" 2157 depends on RELOCATABLE 2158 default y 2159 help 2160 In support of Kernel Address Space Layout Randomization (KASLR), 2161 this randomizes the physical address at which the kernel image 2162 is decompressed and the virtual address where the kernel 2163 image is mapped, as a security feature that deters exploit 2164 attempts relying on knowledge of the location of kernel 2165 code internals. 2166 2167 On 64-bit, the kernel physical and virtual addresses are 2168 randomized separately. The physical address will be anywhere 2169 between 16MB and the top of physical memory (up to 64TB). The 2170 virtual address will be randomized from 16MB up to 1GB (9 bits 2171 of entropy). Note that this also reduces the memory space 2172 available to kernel modules from 1.5GB to 1GB. 2173 2174 On 32-bit, the kernel physical and virtual addresses are 2175 randomized together. They will be randomized from 16MB up to 2176 512MB (8 bits of entropy). 2177 2178 Entropy is generated using the RDRAND instruction if it is 2179 supported. If RDTSC is supported, its value is mixed into 2180 the entropy pool as well. If neither RDRAND nor RDTSC are 2181 supported, then entropy is read from the i8254 timer. The 2182 usable entropy is limited by the kernel being built using 2183 2GB addressing, and that PHYSICAL_ALIGN must be at a 2184 minimum of 2MB. As a result, only 10 bits of entropy are 2185 theoretically possible, but the implementations are further 2186 limited due to memory layouts. 2187 2188 If unsure, say Y. 2189 2190# Relocation on x86 needs some additional build support 2191config X86_NEED_RELOCS 2192 def_bool y 2193 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2194 2195config PHYSICAL_ALIGN 2196 hex "Alignment value to which kernel should be aligned" 2197 default "0x200000" 2198 range 0x2000 0x1000000 if X86_32 2199 range 0x200000 0x1000000 if X86_64 2200 help 2201 This value puts the alignment restrictions on physical address 2202 where kernel is loaded and run from. Kernel is compiled for an 2203 address which meets above alignment restriction. 2204 2205 If bootloader loads the kernel at a non-aligned address and 2206 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2207 address aligned to above value and run from there. 2208 2209 If bootloader loads the kernel at a non-aligned address and 2210 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2211 load address and decompress itself to the address it has been 2212 compiled for and run from there. The address for which kernel is 2213 compiled already meets above alignment restrictions. Hence the 2214 end result is that kernel runs from a physical address meeting 2215 above alignment restrictions. 2216 2217 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2218 this value must be a multiple of 0x200000. 2219 2220 Don't change this unless you know what you are doing. 2221 2222config DYNAMIC_MEMORY_LAYOUT 2223 bool 2224 help 2225 This option makes base addresses of vmalloc and vmemmap as well as 2226 __PAGE_OFFSET movable during boot. 2227 2228config RANDOMIZE_MEMORY 2229 bool "Randomize the kernel memory sections" 2230 depends on X86_64 2231 depends on RANDOMIZE_BASE 2232 select DYNAMIC_MEMORY_LAYOUT 2233 default RANDOMIZE_BASE 2234 help 2235 Randomizes the base virtual address of kernel memory sections 2236 (physical memory mapping, vmalloc & vmemmap). This security feature 2237 makes exploits relying on predictable memory locations less reliable. 2238 2239 The order of allocations remains unchanged. Entropy is generated in 2240 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2241 configuration have in average 30,000 different possible virtual 2242 addresses for each memory section. 2243 2244 If unsure, say Y. 2245 2246config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2247 hex "Physical memory mapping padding" if EXPERT 2248 depends on RANDOMIZE_MEMORY 2249 default "0xa" if MEMORY_HOTPLUG 2250 default "0x0" 2251 range 0x1 0x40 if MEMORY_HOTPLUG 2252 range 0x0 0x40 2253 help 2254 Define the padding in terabytes added to the existing physical 2255 memory size during kernel memory randomization. It is useful 2256 for memory hotplug support but reduces the entropy available for 2257 address randomization. 2258 2259 If unsure, leave at the default value. 2260 2261config ADDRESS_MASKING 2262 bool "Linear Address Masking support" 2263 depends on X86_64 2264 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2265 help 2266 Linear Address Masking (LAM) modifies the checking that is applied 2267 to 64-bit linear addresses, allowing software to use of the 2268 untranslated address bits for metadata. 2269 2270 The capability can be used for efficient address sanitizers (ASAN) 2271 implementation and for optimizations in JITs. 2272 2273config HOTPLUG_CPU 2274 def_bool y 2275 depends on SMP 2276 2277config COMPAT_VDSO 2278 def_bool n 2279 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2280 depends on COMPAT_32 2281 help 2282 Certain buggy versions of glibc will crash if they are 2283 presented with a 32-bit vDSO that is not mapped at the address 2284 indicated in its segment table. 2285 2286 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2287 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2288 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2289 the only released version with the bug, but OpenSUSE 9 2290 contains a buggy "glibc 2.3.2". 2291 2292 The symptom of the bug is that everything crashes on startup, saying: 2293 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2294 2295 Saying Y here changes the default value of the vdso32 boot 2296 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2297 This works around the glibc bug but hurts performance. 2298 2299 If unsure, say N: if you are compiling your own kernel, you 2300 are unlikely to be using a buggy version of glibc. 2301 2302choice 2303 prompt "vsyscall table for legacy applications" 2304 depends on X86_64 2305 default LEGACY_VSYSCALL_XONLY 2306 help 2307 Legacy user code that does not know how to find the vDSO expects 2308 to be able to issue three syscalls by calling fixed addresses in 2309 kernel space. Since this location is not randomized with ASLR, 2310 it can be used to assist security vulnerability exploitation. 2311 2312 This setting can be changed at boot time via the kernel command 2313 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2314 is deprecated and can only be enabled using the kernel command 2315 line. 2316 2317 On a system with recent enough glibc (2.14 or newer) and no 2318 static binaries, you can say None without a performance penalty 2319 to improve security. 2320 2321 If unsure, select "Emulate execution only". 2322 2323 config LEGACY_VSYSCALL_XONLY 2324 bool "Emulate execution only" 2325 help 2326 The kernel traps and emulates calls into the fixed vsyscall 2327 address mapping and does not allow reads. This 2328 configuration is recommended when userspace might use the 2329 legacy vsyscall area but support for legacy binary 2330 instrumentation of legacy code is not needed. It mitigates 2331 certain uses of the vsyscall area as an ASLR-bypassing 2332 buffer. 2333 2334 config LEGACY_VSYSCALL_NONE 2335 bool "None" 2336 help 2337 There will be no vsyscall mapping at all. This will 2338 eliminate any risk of ASLR bypass due to the vsyscall 2339 fixed address mapping. Attempts to use the vsyscalls 2340 will be reported to dmesg, so that either old or 2341 malicious userspace programs can be identified. 2342 2343endchoice 2344 2345config CMDLINE_BOOL 2346 bool "Built-in kernel command line" 2347 help 2348 Allow for specifying boot arguments to the kernel at 2349 build time. On some systems (e.g. embedded ones), it is 2350 necessary or convenient to provide some or all of the 2351 kernel boot arguments with the kernel itself (that is, 2352 to not rely on the boot loader to provide them.) 2353 2354 To compile command line arguments into the kernel, 2355 set this option to 'Y', then fill in the 2356 boot arguments in CONFIG_CMDLINE. 2357 2358 Systems with fully functional boot loaders (i.e. non-embedded) 2359 should leave this option set to 'N'. 2360 2361config CMDLINE 2362 string "Built-in kernel command string" 2363 depends on CMDLINE_BOOL 2364 default "" 2365 help 2366 Enter arguments here that should be compiled into the kernel 2367 image and used at boot time. If the boot loader provides a 2368 command line at boot time, it is appended to this string to 2369 form the full kernel command line, when the system boots. 2370 2371 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2372 change this behavior. 2373 2374 In most cases, the command line (whether built-in or provided 2375 by the boot loader) should specify the device for the root 2376 file system. 2377 2378config CMDLINE_OVERRIDE 2379 bool "Built-in command line overrides boot loader arguments" 2380 depends on CMDLINE_BOOL && CMDLINE != "" 2381 help 2382 Set this option to 'Y' to have the kernel ignore the boot loader 2383 command line, and use ONLY the built-in command line. 2384 2385 This is used to work around broken boot loaders. This should 2386 be set to 'N' under normal conditions. 2387 2388config MODIFY_LDT_SYSCALL 2389 bool "Enable the LDT (local descriptor table)" if EXPERT 2390 default y 2391 help 2392 Linux can allow user programs to install a per-process x86 2393 Local Descriptor Table (LDT) using the modify_ldt(2) system 2394 call. This is required to run 16-bit or segmented code such as 2395 DOSEMU or some Wine programs. It is also used by some very old 2396 threading libraries. 2397 2398 Enabling this feature adds a small amount of overhead to 2399 context switches and increases the low-level kernel attack 2400 surface. Disabling it removes the modify_ldt(2) system call. 2401 2402 Saying 'N' here may make sense for embedded or server kernels. 2403 2404config STRICT_SIGALTSTACK_SIZE 2405 bool "Enforce strict size checking for sigaltstack" 2406 depends on DYNAMIC_SIGFRAME 2407 help 2408 For historical reasons MINSIGSTKSZ is a constant which became 2409 already too small with AVX512 support. Add a mechanism to 2410 enforce strict checking of the sigaltstack size against the 2411 real size of the FPU frame. This option enables the check 2412 by default. It can also be controlled via the kernel command 2413 line option 'strict_sas_size' independent of this config 2414 switch. Enabling it might break existing applications which 2415 allocate a too small sigaltstack but 'work' because they 2416 never get a signal delivered. 2417 2418 Say 'N' unless you want to really enforce this check. 2419 2420config CFI_AUTO_DEFAULT 2421 bool "Attempt to use FineIBT by default at boot time" 2422 depends on FINEIBT 2423 default y 2424 help 2425 Attempt to use FineIBT by default at boot time. If enabled, 2426 this is the same as booting with "cfi=auto". If disabled, 2427 this is the same as booting with "cfi=kcfi". 2428 2429source "kernel/livepatch/Kconfig" 2430 2431endmenu 2432 2433config CC_HAS_NAMED_AS 2434 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null) 2435 depends on CC_IS_GCC 2436 2437config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2438 def_bool CC_IS_GCC && GCC_VERSION >= 130300 2439 2440config USE_X86_SEG_SUPPORT 2441 def_bool y 2442 depends on CC_HAS_NAMED_AS 2443 # 2444 # -fsanitize=kernel-address (KASAN) and -fsanitize=thread 2445 # (KCSAN) are incompatible with named address spaces with 2446 # GCC < 13.3 - see GCC PR sanitizer/111736. 2447 # 2448 depends on !(KASAN || KCSAN) || CC_HAS_NAMED_AS_FIXED_SANITIZERS 2449 2450config CC_HAS_SLS 2451 def_bool $(cc-option,-mharden-sls=all) 2452 2453config CC_HAS_RETURN_THUNK 2454 def_bool $(cc-option,-mfunction-return=thunk-extern) 2455 2456config CC_HAS_ENTRY_PADDING 2457 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2458 2459config FUNCTION_PADDING_CFI 2460 int 2461 default 59 if FUNCTION_ALIGNMENT_64B 2462 default 27 if FUNCTION_ALIGNMENT_32B 2463 default 11 if FUNCTION_ALIGNMENT_16B 2464 default 3 if FUNCTION_ALIGNMENT_8B 2465 default 0 2466 2467# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2468# except Kconfig can't do arithmetic :/ 2469config FUNCTION_PADDING_BYTES 2470 int 2471 default FUNCTION_PADDING_CFI if CFI_CLANG 2472 default FUNCTION_ALIGNMENT 2473 2474config CALL_PADDING 2475 def_bool n 2476 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2477 select FUNCTION_ALIGNMENT_16B 2478 2479config FINEIBT 2480 def_bool y 2481 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE 2482 select CALL_PADDING 2483 2484config HAVE_CALL_THUNKS 2485 def_bool y 2486 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2487 2488config CALL_THUNKS 2489 def_bool n 2490 select CALL_PADDING 2491 2492config PREFIX_SYMBOLS 2493 def_bool y 2494 depends on CALL_PADDING && !CFI_CLANG 2495 2496menuconfig CPU_MITIGATIONS 2497 bool "Mitigations for CPU vulnerabilities" 2498 default y 2499 help 2500 Say Y here to enable options which enable mitigations for hardware 2501 vulnerabilities (usually related to speculative execution). 2502 Mitigations can be disabled or restricted to SMT systems at runtime 2503 via the "mitigations" kernel parameter. 2504 2505 If you say N, all mitigations will be disabled. This CANNOT be 2506 overridden at runtime. 2507 2508 Say 'Y', unless you really know what you are doing. 2509 2510if CPU_MITIGATIONS 2511 2512config MITIGATION_PAGE_TABLE_ISOLATION 2513 bool "Remove the kernel mapping in user mode" 2514 default y 2515 depends on (X86_64 || X86_PAE) 2516 help 2517 This feature reduces the number of hardware side channels by 2518 ensuring that the majority of kernel addresses are not mapped 2519 into userspace. 2520 2521 See Documentation/arch/x86/pti.rst for more details. 2522 2523config MITIGATION_RETPOLINE 2524 bool "Avoid speculative indirect branches in kernel" 2525 select OBJTOOL if HAVE_OBJTOOL 2526 default y 2527 help 2528 Compile kernel with the retpoline compiler options to guard against 2529 kernel-to-user data leaks by avoiding speculative indirect 2530 branches. Requires a compiler with -mindirect-branch=thunk-extern 2531 support for full protection. The kernel may run slower. 2532 2533config MITIGATION_RETHUNK 2534 bool "Enable return-thunks" 2535 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2536 select OBJTOOL if HAVE_OBJTOOL 2537 default y if X86_64 2538 help 2539 Compile the kernel with the return-thunks compiler option to guard 2540 against kernel-to-user data leaks by avoiding return speculation. 2541 Requires a compiler with -mfunction-return=thunk-extern 2542 support for full protection. The kernel may run slower. 2543 2544config MITIGATION_UNRET_ENTRY 2545 bool "Enable UNRET on kernel entry" 2546 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2547 default y 2548 help 2549 Compile the kernel with support for the retbleed=unret mitigation. 2550 2551config MITIGATION_CALL_DEPTH_TRACKING 2552 bool "Mitigate RSB underflow with call depth tracking" 2553 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2554 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2555 select CALL_THUNKS 2556 default y 2557 help 2558 Compile the kernel with call depth tracking to mitigate the Intel 2559 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2560 mitigation is off by default and needs to be enabled on the 2561 kernel command line via the retbleed=stuff option. For 2562 non-affected systems the overhead of this option is marginal as 2563 the call depth tracking is using run-time generated call thunks 2564 in a compiler generated padding area and call patching. This 2565 increases text size by ~5%. For non affected systems this space 2566 is unused. On affected SKL systems this results in a significant 2567 performance gain over the IBRS mitigation. 2568 2569config CALL_THUNKS_DEBUG 2570 bool "Enable call thunks and call depth tracking debugging" 2571 depends on MITIGATION_CALL_DEPTH_TRACKING 2572 select FUNCTION_ALIGNMENT_32B 2573 default n 2574 help 2575 Enable call/ret counters for imbalance detection and build in 2576 a noisy dmesg about callthunks generation and call patching for 2577 trouble shooting. The debug prints need to be enabled on the 2578 kernel command line with 'debug-callthunks'. 2579 Only enable this when you are debugging call thunks as this 2580 creates a noticeable runtime overhead. If unsure say N. 2581 2582config MITIGATION_IBPB_ENTRY 2583 bool "Enable IBPB on kernel entry" 2584 depends on CPU_SUP_AMD && X86_64 2585 default y 2586 help 2587 Compile the kernel with support for the retbleed=ibpb mitigation. 2588 2589config MITIGATION_IBRS_ENTRY 2590 bool "Enable IBRS on kernel entry" 2591 depends on CPU_SUP_INTEL && X86_64 2592 default y 2593 help 2594 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2595 This mitigates both spectre_v2 and retbleed at great cost to 2596 performance. 2597 2598config MITIGATION_SRSO 2599 bool "Mitigate speculative RAS overflow on AMD" 2600 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2601 default y 2602 help 2603 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2604 2605config MITIGATION_SLS 2606 bool "Mitigate Straight-Line-Speculation" 2607 depends on CC_HAS_SLS && X86_64 2608 select OBJTOOL if HAVE_OBJTOOL 2609 default n 2610 help 2611 Compile the kernel with straight-line-speculation options to guard 2612 against straight line speculation. The kernel image might be slightly 2613 larger. 2614 2615config MITIGATION_GDS 2616 bool "Mitigate Gather Data Sampling" 2617 depends on CPU_SUP_INTEL 2618 default y 2619 help 2620 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware 2621 vulnerability which allows unprivileged speculative access to data 2622 which was previously stored in vector registers. The attacker uses gather 2623 instructions to infer the stale vector register data. 2624 2625config MITIGATION_RFDS 2626 bool "RFDS Mitigation" 2627 depends on CPU_SUP_INTEL 2628 default y 2629 help 2630 Enable mitigation for Register File Data Sampling (RFDS) by default. 2631 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2632 allows unprivileged speculative access to stale data previously 2633 stored in floating point, vector and integer registers. 2634 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2635 2636config MITIGATION_SPECTRE_BHI 2637 bool "Mitigate Spectre-BHB (Branch History Injection)" 2638 depends on CPU_SUP_INTEL 2639 default y 2640 help 2641 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2642 where the branch history buffer is poisoned to speculatively steer 2643 indirect branches. 2644 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2645 2646config MITIGATION_MDS 2647 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug" 2648 depends on CPU_SUP_INTEL 2649 default y 2650 help 2651 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is 2652 a hardware vulnerability which allows unprivileged speculative access 2653 to data which is available in various CPU internal buffers. 2654 See also <file:Documentation/admin-guide/hw-vuln/mds.rst> 2655 2656config MITIGATION_TAA 2657 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug" 2658 depends on CPU_SUP_INTEL 2659 default y 2660 help 2661 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware 2662 vulnerability that allows unprivileged speculative access to data 2663 which is available in various CPU internal buffers by using 2664 asynchronous aborts within an Intel TSX transactional region. 2665 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst> 2666 2667config MITIGATION_MMIO_STALE_DATA 2668 bool "Mitigate MMIO Stale Data hardware bug" 2669 depends on CPU_SUP_INTEL 2670 default y 2671 help 2672 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO 2673 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO) 2674 vulnerabilities that can expose data. The vulnerabilities require the 2675 attacker to have access to MMIO. 2676 See also 2677 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst> 2678 2679config MITIGATION_L1TF 2680 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug" 2681 depends on CPU_SUP_INTEL 2682 default y 2683 help 2684 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a 2685 hardware vulnerability which allows unprivileged speculative access to data 2686 available in the Level 1 Data Cache. 2687 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst 2688 2689config MITIGATION_RETBLEED 2690 bool "Mitigate RETBleed hardware bug" 2691 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY 2692 default y 2693 help 2694 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution 2695 with Return Instructions) vulnerability. RETBleed is a speculative 2696 execution attack which takes advantage of microarchitectural behavior 2697 in many modern microprocessors, similar to Spectre v2. An 2698 unprivileged attacker can use these flaws to bypass conventional 2699 memory security restrictions to gain read access to privileged memory 2700 that would otherwise be inaccessible. 2701 2702config MITIGATION_SPECTRE_V1 2703 bool "Mitigate SPECTRE V1 hardware bug" 2704 default y 2705 help 2706 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a 2707 class of side channel attacks that takes advantage of speculative 2708 execution that bypasses conditional branch instructions used for 2709 memory access bounds check. 2710 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2711 2712config MITIGATION_SPECTRE_V2 2713 bool "Mitigate SPECTRE V2 hardware bug" 2714 default y 2715 help 2716 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre 2717 V2 is a class of side channel attacks that takes advantage of 2718 indirect branch predictors inside the processor. In Spectre variant 2 2719 attacks, the attacker can steer speculative indirect branches in the 2720 victim to gadget code by poisoning the branch target buffer of a CPU 2721 used for predicting indirect branch addresses. 2722 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2723 2724config MITIGATION_SRBDS 2725 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug" 2726 depends on CPU_SUP_INTEL 2727 default y 2728 help 2729 Enable mitigation for Special Register Buffer Data Sampling (SRBDS). 2730 SRBDS is a hardware vulnerability that allows Microarchitectural Data 2731 Sampling (MDS) techniques to infer values returned from special 2732 register accesses. An unprivileged user can extract values returned 2733 from RDRAND and RDSEED executed on another core or sibling thread 2734 using MDS techniques. 2735 See also 2736 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst> 2737 2738config MITIGATION_SSB 2739 bool "Mitigate Speculative Store Bypass (SSB) hardware bug" 2740 default y 2741 help 2742 Enable mitigation for Speculative Store Bypass (SSB). SSB is a 2743 hardware security vulnerability and its exploitation takes advantage 2744 of speculative execution in a similar way to the Meltdown and Spectre 2745 security vulnerabilities. 2746 2747endif 2748 2749config ARCH_HAS_ADD_PAGES 2750 def_bool y 2751 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2752 2753menu "Power management and ACPI options" 2754 2755config ARCH_HIBERNATION_HEADER 2756 def_bool y 2757 depends on HIBERNATION 2758 2759source "kernel/power/Kconfig" 2760 2761source "drivers/acpi/Kconfig" 2762 2763config X86_APM_BOOT 2764 def_bool y 2765 depends on APM 2766 2767menuconfig APM 2768 tristate "APM (Advanced Power Management) BIOS support" 2769 depends on X86_32 && PM_SLEEP 2770 help 2771 APM is a BIOS specification for saving power using several different 2772 techniques. This is mostly useful for battery powered laptops with 2773 APM compliant BIOSes. If you say Y here, the system time will be 2774 reset after a RESUME operation, the /proc/apm device will provide 2775 battery status information, and user-space programs will receive 2776 notification of APM "events" (e.g. battery status change). 2777 2778 If you select "Y" here, you can disable actual use of the APM 2779 BIOS by passing the "apm=off" option to the kernel at boot time. 2780 2781 Note that the APM support is almost completely disabled for 2782 machines with more than one CPU. 2783 2784 In order to use APM, you will need supporting software. For location 2785 and more information, read <file:Documentation/power/apm-acpi.rst> 2786 and the Battery Powered Linux mini-HOWTO, available from 2787 <http://www.tldp.org/docs.html#howto>. 2788 2789 This driver does not spin down disk drives (see the hdparm(8) 2790 manpage ("man 8 hdparm") for that), and it doesn't turn off 2791 VESA-compliant "green" monitors. 2792 2793 This driver does not support the TI 4000M TravelMate and the ACER 2794 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2795 desktop machines also don't have compliant BIOSes, and this driver 2796 may cause those machines to panic during the boot phase. 2797 2798 Generally, if you don't have a battery in your machine, there isn't 2799 much point in using this driver and you should say N. If you get 2800 random kernel OOPSes or reboots that don't seem to be related to 2801 anything, try disabling/enabling this option (or disabling/enabling 2802 APM in your BIOS). 2803 2804 Some other things you should try when experiencing seemingly random, 2805 "weird" problems: 2806 2807 1) make sure that you have enough swap space and that it is 2808 enabled. 2809 2) pass the "idle=poll" option to the kernel 2810 3) switch on floating point emulation in the kernel and pass 2811 the "no387" option to the kernel 2812 4) pass the "floppy=nodma" option to the kernel 2813 5) pass the "mem=4M" option to the kernel (thereby disabling 2814 all but the first 4 MB of RAM) 2815 6) make sure that the CPU is not over clocked. 2816 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2817 8) disable the cache from your BIOS settings 2818 9) install a fan for the video card or exchange video RAM 2819 10) install a better fan for the CPU 2820 11) exchange RAM chips 2821 12) exchange the motherboard. 2822 2823 To compile this driver as a module, choose M here: the 2824 module will be called apm. 2825 2826if APM 2827 2828config APM_IGNORE_USER_SUSPEND 2829 bool "Ignore USER SUSPEND" 2830 help 2831 This option will ignore USER SUSPEND requests. On machines with a 2832 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2833 series notebooks, it is necessary to say Y because of a BIOS bug. 2834 2835config APM_DO_ENABLE 2836 bool "Enable PM at boot time" 2837 help 2838 Enable APM features at boot time. From page 36 of the APM BIOS 2839 specification: "When disabled, the APM BIOS does not automatically 2840 power manage devices, enter the Standby State, enter the Suspend 2841 State, or take power saving steps in response to CPU Idle calls." 2842 This driver will make CPU Idle calls when Linux is idle (unless this 2843 feature is turned off -- see "Do CPU IDLE calls", below). This 2844 should always save battery power, but more complicated APM features 2845 will be dependent on your BIOS implementation. You may need to turn 2846 this option off if your computer hangs at boot time when using APM 2847 support, or if it beeps continuously instead of suspending. Turn 2848 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2849 T400CDT. This is off by default since most machines do fine without 2850 this feature. 2851 2852config APM_CPU_IDLE 2853 depends on CPU_IDLE 2854 bool "Make CPU Idle calls when idle" 2855 help 2856 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2857 On some machines, this can activate improved power savings, such as 2858 a slowed CPU clock rate, when the machine is idle. These idle calls 2859 are made after the idle loop has run for some length of time (e.g., 2860 333 mS). On some machines, this will cause a hang at boot time or 2861 whenever the CPU becomes idle. (On machines with more than one CPU, 2862 this option does nothing.) 2863 2864config APM_DISPLAY_BLANK 2865 bool "Enable console blanking using APM" 2866 help 2867 Enable console blanking using the APM. Some laptops can use this to 2868 turn off the LCD backlight when the screen blanker of the Linux 2869 virtual console blanks the screen. Note that this is only used by 2870 the virtual console screen blanker, and won't turn off the backlight 2871 when using the X Window system. This also doesn't have anything to 2872 do with your VESA-compliant power-saving monitor. Further, this 2873 option doesn't work for all laptops -- it might not turn off your 2874 backlight at all, or it might print a lot of errors to the console, 2875 especially if you are using gpm. 2876 2877config APM_ALLOW_INTS 2878 bool "Allow interrupts during APM BIOS calls" 2879 help 2880 Normally we disable external interrupts while we are making calls to 2881 the APM BIOS as a measure to lessen the effects of a badly behaving 2882 BIOS implementation. The BIOS should reenable interrupts if it 2883 needs to. Unfortunately, some BIOSes do not -- especially those in 2884 many of the newer IBM Thinkpads. If you experience hangs when you 2885 suspend, try setting this to Y. Otherwise, say N. 2886 2887endif # APM 2888 2889source "drivers/cpufreq/Kconfig" 2890 2891source "drivers/cpuidle/Kconfig" 2892 2893source "drivers/idle/Kconfig" 2894 2895endmenu 2896 2897menu "Bus options (PCI etc.)" 2898 2899choice 2900 prompt "PCI access mode" 2901 depends on X86_32 && PCI 2902 default PCI_GOANY 2903 help 2904 On PCI systems, the BIOS can be used to detect the PCI devices and 2905 determine their configuration. However, some old PCI motherboards 2906 have BIOS bugs and may crash if this is done. Also, some embedded 2907 PCI-based systems don't have any BIOS at all. Linux can also try to 2908 detect the PCI hardware directly without using the BIOS. 2909 2910 With this option, you can specify how Linux should detect the 2911 PCI devices. If you choose "BIOS", the BIOS will be used, 2912 if you choose "Direct", the BIOS won't be used, and if you 2913 choose "MMConfig", then PCI Express MMCONFIG will be used. 2914 If you choose "Any", the kernel will try MMCONFIG, then the 2915 direct access method and falls back to the BIOS if that doesn't 2916 work. If unsure, go with the default, which is "Any". 2917 2918config PCI_GOBIOS 2919 bool "BIOS" 2920 2921config PCI_GOMMCONFIG 2922 bool "MMConfig" 2923 2924config PCI_GODIRECT 2925 bool "Direct" 2926 2927config PCI_GOOLPC 2928 bool "OLPC XO-1" 2929 depends on OLPC 2930 2931config PCI_GOANY 2932 bool "Any" 2933 2934endchoice 2935 2936config PCI_BIOS 2937 def_bool y 2938 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2939 2940# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2941config PCI_DIRECT 2942 def_bool y 2943 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2944 2945config PCI_MMCONFIG 2946 bool "Support mmconfig PCI config space access" if X86_64 2947 default y 2948 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2949 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2950 2951config PCI_OLPC 2952 def_bool y 2953 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2954 2955config PCI_XEN 2956 def_bool y 2957 depends on PCI && XEN 2958 2959config MMCONF_FAM10H 2960 def_bool y 2961 depends on X86_64 && PCI_MMCONFIG && ACPI 2962 2963config PCI_CNB20LE_QUIRK 2964 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2965 depends on PCI 2966 help 2967 Read the PCI windows out of the CNB20LE host bridge. This allows 2968 PCI hotplug to work on systems with the CNB20LE chipset which do 2969 not have ACPI. 2970 2971 There's no public spec for this chipset, and this functionality 2972 is known to be incomplete. 2973 2974 You should say N unless you know you need this. 2975 2976config ISA_BUS 2977 bool "ISA bus support on modern systems" if EXPERT 2978 help 2979 Expose ISA bus device drivers and options available for selection and 2980 configuration. Enable this option if your target machine has an ISA 2981 bus. ISA is an older system, displaced by PCI and newer bus 2982 architectures -- if your target machine is modern, it probably does 2983 not have an ISA bus. 2984 2985 If unsure, say N. 2986 2987# x86_64 have no ISA slots, but can have ISA-style DMA. 2988config ISA_DMA_API 2989 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2990 default y 2991 help 2992 Enables ISA-style DMA support for devices requiring such controllers. 2993 If unsure, say Y. 2994 2995if X86_32 2996 2997config ISA 2998 bool "ISA support" 2999 help 3000 Find out whether you have ISA slots on your motherboard. ISA is the 3001 name of a bus system, i.e. the way the CPU talks to the other stuff 3002 inside your box. Other bus systems are PCI, EISA, MicroChannel 3003 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 3004 newer boards don't support it. If you have ISA, say Y, otherwise N. 3005 3006config SCx200 3007 tristate "NatSemi SCx200 support" 3008 help 3009 This provides basic support for National Semiconductor's 3010 (now AMD's) Geode processors. The driver probes for the 3011 PCI-IDs of several on-chip devices, so its a good dependency 3012 for other scx200_* drivers. 3013 3014 If compiled as a module, the driver is named scx200. 3015 3016config SCx200HR_TIMER 3017 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 3018 depends on SCx200 3019 default y 3020 help 3021 This driver provides a clocksource built upon the on-chip 3022 27MHz high-resolution timer. Its also a workaround for 3023 NSC Geode SC-1100's buggy TSC, which loses time when the 3024 processor goes idle (as is done by the scheduler). The 3025 other workaround is idle=poll boot option. 3026 3027config OLPC 3028 bool "One Laptop Per Child support" 3029 depends on !X86_PAE 3030 select GPIOLIB 3031 select OF 3032 select OF_PROMTREE 3033 select IRQ_DOMAIN 3034 select OLPC_EC 3035 help 3036 Add support for detecting the unique features of the OLPC 3037 XO hardware. 3038 3039config OLPC_XO1_PM 3040 bool "OLPC XO-1 Power Management" 3041 depends on OLPC && MFD_CS5535=y && PM_SLEEP 3042 help 3043 Add support for poweroff and suspend of the OLPC XO-1 laptop. 3044 3045config OLPC_XO1_RTC 3046 bool "OLPC XO-1 Real Time Clock" 3047 depends on OLPC_XO1_PM && RTC_DRV_CMOS 3048 help 3049 Add support for the XO-1 real time clock, which can be used as a 3050 programmable wakeup source. 3051 3052config OLPC_XO1_SCI 3053 bool "OLPC XO-1 SCI extras" 3054 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 3055 depends on INPUT=y 3056 select POWER_SUPPLY 3057 help 3058 Add support for SCI-based features of the OLPC XO-1 laptop: 3059 - EC-driven system wakeups 3060 - Power button 3061 - Ebook switch 3062 - Lid switch 3063 - AC adapter status updates 3064 - Battery status updates 3065 3066config OLPC_XO15_SCI 3067 bool "OLPC XO-1.5 SCI extras" 3068 depends on OLPC && ACPI 3069 select POWER_SUPPLY 3070 help 3071 Add support for SCI-based features of the OLPC XO-1.5 laptop: 3072 - EC-driven system wakeups 3073 - AC adapter status updates 3074 - Battery status updates 3075 3076config GEODE_COMMON 3077 bool 3078 3079config ALIX 3080 bool "PCEngines ALIX System Support (LED setup)" 3081 select GPIOLIB 3082 select GEODE_COMMON 3083 help 3084 This option enables system support for the PCEngines ALIX. 3085 At present this just sets up LEDs for GPIO control on 3086 ALIX2/3/6 boards. However, other system specific setup should 3087 get added here. 3088 3089 Note: You must still enable the drivers for GPIO and LED support 3090 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 3091 3092 Note: You have to set alix.force=1 for boards with Award BIOS. 3093 3094config NET5501 3095 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3096 select GPIOLIB 3097 select GEODE_COMMON 3098 help 3099 This option enables system support for the Soekris Engineering net5501. 3100 3101config GEOS 3102 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3103 select GPIOLIB 3104 select GEODE_COMMON 3105 depends on DMI 3106 help 3107 This option enables system support for the Traverse Technologies GEOS. 3108 3109config TS5500 3110 bool "Technologic Systems TS-5500 platform support" 3111 depends on MELAN 3112 select CHECK_SIGNATURE 3113 select NEW_LEDS 3114 select LEDS_CLASS 3115 help 3116 This option enables system support for the Technologic Systems TS-5500. 3117 3118endif # X86_32 3119 3120config AMD_NB 3121 def_bool y 3122 depends on CPU_SUP_AMD && PCI 3123 3124endmenu 3125 3126menu "Binary Emulations" 3127 3128config IA32_EMULATION 3129 bool "IA32 Emulation" 3130 depends on X86_64 3131 select ARCH_WANT_OLD_COMPAT_IPC 3132 select BINFMT_ELF 3133 select COMPAT_OLD_SIGACTION 3134 help 3135 Include code to run legacy 32-bit programs under a 3136 64-bit kernel. You should likely turn this on, unless you're 3137 100% sure that you don't have any 32-bit programs left. 3138 3139config IA32_EMULATION_DEFAULT_DISABLED 3140 bool "IA32 emulation disabled by default" 3141 default n 3142 depends on IA32_EMULATION 3143 help 3144 Make IA32 emulation disabled by default. This prevents loading 32-bit 3145 processes and access to 32-bit syscalls. If unsure, leave it to its 3146 default value. 3147 3148config X86_X32_ABI 3149 bool "x32 ABI for 64-bit mode" 3150 depends on X86_64 3151 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3152 # compressed debug sections to x86_x32 properly: 3153 # https://github.com/ClangBuiltLinux/linux/issues/514 3154 # https://github.com/ClangBuiltLinux/linux/issues/1141 3155 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3156 help 3157 Include code to run binaries for the x32 native 32-bit ABI 3158 for 64-bit processors. An x32 process gets access to the 3159 full 64-bit register file and wide data path while leaving 3160 pointers at 32 bits for smaller memory footprint. 3161 3162config COMPAT_32 3163 def_bool y 3164 depends on IA32_EMULATION || X86_32 3165 select HAVE_UID16 3166 select OLD_SIGSUSPEND3 3167 3168config COMPAT 3169 def_bool y 3170 depends on IA32_EMULATION || X86_X32_ABI 3171 3172config COMPAT_FOR_U64_ALIGNMENT 3173 def_bool y 3174 depends on COMPAT 3175 3176endmenu 3177 3178config HAVE_ATOMIC_IOMAP 3179 def_bool y 3180 depends on X86_32 3181 3182source "arch/x86/kvm/Kconfig" 3183 3184source "arch/x86/Kconfig.assembler" 3185