1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE 32 select HAVE_ARCH_SOFT_DIRTY 33 select MODULES_USE_ELF_RELA 34 select NEED_DMA_MAP_STATE 35 select SWIOTLB 36 select ARCH_HAS_ELFCORE_COMPAT 37 select ZONE_DMA32 38 select EXECMEM if DYNAMIC_FTRACE 39 40config FORCE_DYNAMIC_FTRACE 41 def_bool y 42 depends on X86_32 43 depends on FUNCTION_TRACER 44 select DYNAMIC_FTRACE 45 help 46 We keep the static function tracing (!DYNAMIC_FTRACE) around 47 in order to test the non static function tracing in the 48 generic code, as other architectures still use it. But we 49 only need to keep it around for x86_64. No need to keep it 50 for x86_32. For x86_32, force DYNAMIC_FTRACE. 51# 52# Arch settings 53# 54# ( Note that options that are marked 'if X86_64' could in principle be 55# ported to 32-bit as well. ) 56# 57config X86 58 def_bool y 59 # 60 # Note: keep this list sorted alphabetically 61 # 62 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 63 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 64 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 65 select ARCH_32BIT_OFF_T if X86_32 66 select ARCH_CLOCKSOURCE_INIT 67 select ARCH_CONFIGURES_CPU_MITIGATIONS 68 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 69 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 70 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 71 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 72 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 73 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 74 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 75 select ARCH_HAS_CACHE_LINE_SIZE 76 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 77 select ARCH_HAS_CPU_FINALIZE_INIT 78 select ARCH_HAS_CPU_PASID if IOMMU_SVA 79 select ARCH_HAS_CURRENT_STACK_POINTER 80 select ARCH_HAS_DEBUG_VIRTUAL 81 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 82 select ARCH_HAS_DEVMEM_IS_ALLOWED 83 select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN 84 select ARCH_HAS_EARLY_DEBUG if KGDB 85 select ARCH_HAS_ELF_RANDOMIZE 86 select ARCH_HAS_FAST_MULTIPLIER 87 select ARCH_HAS_FORTIFY_SOURCE 88 select ARCH_HAS_GCOV_PROFILE_ALL 89 select ARCH_HAS_KCOV if X86_64 90 select ARCH_HAS_KERNEL_FPU_SUPPORT 91 select ARCH_HAS_MEM_ENCRYPT 92 select ARCH_HAS_MEMBARRIER_SYNC_CORE 93 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 94 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 95 select ARCH_HAS_PMEM_API if X86_64 96 select ARCH_HAS_PTE_DEVMAP if X86_64 97 select ARCH_HAS_PTE_SPECIAL 98 select ARCH_HAS_HW_PTE_YOUNG 99 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 100 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 101 select ARCH_HAS_COPY_MC if X86_64 102 select ARCH_HAS_SET_MEMORY 103 select ARCH_HAS_SET_DIRECT_MAP 104 select ARCH_HAS_STRICT_KERNEL_RWX 105 select ARCH_HAS_STRICT_MODULE_RWX 106 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 107 select ARCH_HAS_SYSCALL_WRAPPER 108 select ARCH_HAS_UBSAN 109 select ARCH_HAS_DEBUG_WX 110 select ARCH_HAS_ZONE_DMA_SET if EXPERT 111 select ARCH_HAVE_NMI_SAFE_CMPXCHG 112 select ARCH_HAVE_EXTRA_ELF_NOTES 113 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 114 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 115 select ARCH_MIGHT_HAVE_PC_PARPORT 116 select ARCH_MIGHT_HAVE_PC_SERIO 117 select ARCH_STACKWALK 118 select ARCH_SUPPORTS_ACPI 119 select ARCH_SUPPORTS_ATOMIC_RMW 120 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 121 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 122 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 123 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 124 select ARCH_SUPPORTS_CFI_CLANG if X86_64 125 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 126 select ARCH_SUPPORTS_LTO_CLANG 127 select ARCH_SUPPORTS_LTO_CLANG_THIN 128 select ARCH_SUPPORTS_RT 129 select ARCH_SUPPORTS_AUTOFDO_CLANG 130 select ARCH_SUPPORTS_PROPELLER_CLANG if X86_64 131 select ARCH_USE_BUILTIN_BSWAP 132 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64 133 select ARCH_USE_MEMTEST 134 select ARCH_USE_QUEUED_RWLOCKS 135 select ARCH_USE_QUEUED_SPINLOCKS 136 select ARCH_USE_SYM_ANNOTATIONS 137 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 138 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 139 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 140 select ARCH_WANTS_NO_INSTR 141 select ARCH_WANT_GENERAL_HUGETLB 142 select ARCH_WANT_HUGE_PMD_SHARE 143 select ARCH_WANT_LD_ORPHAN_WARN 144 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 145 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 146 select ARCH_WANTS_THP_SWAP if X86_64 147 select ARCH_HAS_PARANOID_L1D_FLUSH 148 select BUILDTIME_TABLE_SORT 149 select CLKEVT_I8253 150 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 151 select CLOCKSOURCE_WATCHDOG 152 # Word-size accesses may read uninitialized data past the trailing \0 153 # in strings and cause false KMSAN reports. 154 select DCACHE_WORD_ACCESS if !KMSAN 155 select DYNAMIC_SIGFRAME 156 select EDAC_ATOMIC_SCRUB 157 select EDAC_SUPPORT 158 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 159 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 160 select GENERIC_CLOCKEVENTS_MIN_ADJUST 161 select GENERIC_CMOS_UPDATE 162 select GENERIC_CPU_AUTOPROBE 163 select GENERIC_CPU_DEVICES 164 select GENERIC_CPU_VULNERABILITIES 165 select GENERIC_EARLY_IOREMAP 166 select GENERIC_ENTRY 167 select GENERIC_IOMAP 168 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 169 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 170 select GENERIC_IRQ_MIGRATION if SMP 171 select GENERIC_IRQ_PROBE 172 select GENERIC_IRQ_RESERVATION_MODE 173 select GENERIC_IRQ_SHOW 174 select GENERIC_PENDING_IRQ if SMP 175 select GENERIC_PTDUMP 176 select GENERIC_SMP_IDLE_THREAD 177 select GENERIC_TIME_VSYSCALL 178 select GENERIC_GETTIMEOFDAY 179 select GENERIC_VDSO_TIME_NS 180 select GENERIC_VDSO_OVERFLOW_PROTECT 181 select GUP_GET_PXX_LOW_HIGH if X86_PAE 182 select HARDIRQS_SW_RESEND 183 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 184 select HAS_IOPORT 185 select HAVE_ACPI_APEI if ACPI 186 select HAVE_ACPI_APEI_NMI if ACPI 187 select HAVE_ALIGNED_STRUCT_PAGE 188 select HAVE_ARCH_AUDITSYSCALL 189 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 190 select HAVE_ARCH_HUGE_VMALLOC if X86_64 191 select HAVE_ARCH_JUMP_LABEL 192 select HAVE_ARCH_JUMP_LABEL_RELATIVE 193 select HAVE_ARCH_KASAN if X86_64 194 select HAVE_ARCH_KASAN_VMALLOC if X86_64 195 select HAVE_ARCH_KFENCE 196 select HAVE_ARCH_KMSAN if X86_64 197 select HAVE_ARCH_KGDB 198 select HAVE_ARCH_MMAP_RND_BITS if MMU 199 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 200 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 201 select HAVE_ARCH_PREL32_RELOCATIONS 202 select HAVE_ARCH_SECCOMP_FILTER 203 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 204 select HAVE_ARCH_STACKLEAK 205 select HAVE_ARCH_TRACEHOOK 206 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 207 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 208 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 209 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 210 select HAVE_ARCH_VMAP_STACK if X86_64 211 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 212 select HAVE_ARCH_WITHIN_STACK_FRAMES 213 select HAVE_ASM_MODVERSIONS 214 select HAVE_CMPXCHG_DOUBLE 215 select HAVE_CMPXCHG_LOCAL 216 select HAVE_CONTEXT_TRACKING_USER if X86_64 217 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 218 select HAVE_C_RECORDMCOUNT 219 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 220 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 221 select HAVE_BUILDTIME_MCOUNT_SORT 222 select HAVE_DEBUG_KMEMLEAK 223 select HAVE_DMA_CONTIGUOUS 224 select HAVE_DYNAMIC_FTRACE 225 select HAVE_DYNAMIC_FTRACE_WITH_REGS 226 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 227 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 228 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 229 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 230 select HAVE_EBPF_JIT 231 select HAVE_EFFICIENT_UNALIGNED_ACCESS 232 select HAVE_EISA 233 select HAVE_EXIT_THREAD 234 select HAVE_GUP_FAST 235 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 236 select HAVE_FTRACE_MCOUNT_RECORD 237 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 238 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 239 select HAVE_FUNCTION_TRACER 240 select HAVE_GCC_PLUGINS 241 select HAVE_HW_BREAKPOINT 242 select HAVE_IOREMAP_PROT 243 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 244 select HAVE_IRQ_TIME_ACCOUNTING 245 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 246 select HAVE_KERNEL_BZIP2 247 select HAVE_KERNEL_GZIP 248 select HAVE_KERNEL_LZ4 249 select HAVE_KERNEL_LZMA 250 select HAVE_KERNEL_LZO 251 select HAVE_KERNEL_XZ 252 select HAVE_KERNEL_ZSTD 253 select HAVE_KPROBES 254 select HAVE_KPROBES_ON_FTRACE 255 select HAVE_FUNCTION_ERROR_INJECTION 256 select HAVE_KRETPROBES 257 select HAVE_RETHOOK 258 select HAVE_LIVEPATCH if X86_64 259 select HAVE_MIXED_BREAKPOINTS_REGS 260 select HAVE_MOD_ARCH_SPECIFIC 261 select HAVE_MOVE_PMD 262 select HAVE_MOVE_PUD 263 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 264 select HAVE_NMI 265 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 266 select HAVE_OBJTOOL if X86_64 267 select HAVE_OPTPROBES 268 select HAVE_PAGE_SIZE_4KB 269 select HAVE_PCSPKR_PLATFORM 270 select HAVE_PERF_EVENTS 271 select HAVE_PERF_EVENTS_NMI 272 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 273 select HAVE_PCI 274 select HAVE_PERF_REGS 275 select HAVE_PERF_USER_STACK_DUMP 276 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 277 select MMU_GATHER_MERGE_VMAS 278 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 279 select HAVE_REGS_AND_STACK_ACCESS_API 280 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 281 select HAVE_FUNCTION_ARG_ACCESS_API 282 select HAVE_SETUP_PER_CPU_AREA 283 select HAVE_SOFTIRQ_ON_OWN_STACK 284 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 285 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 286 select HAVE_STATIC_CALL 287 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 288 select HAVE_PREEMPT_DYNAMIC_CALL 289 select HAVE_RSEQ 290 select HAVE_RUST if X86_64 291 select HAVE_SYSCALL_TRACEPOINTS 292 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 293 select HAVE_UNSTABLE_SCHED_CLOCK 294 select HAVE_USER_RETURN_NOTIFIER 295 select HAVE_GENERIC_VDSO 296 select VDSO_GETRANDOM if X86_64 297 select HOTPLUG_PARALLEL if SMP && X86_64 298 select HOTPLUG_SMT if SMP 299 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 300 select IRQ_FORCED_THREADING 301 select LOCK_MM_AND_FIND_VMA 302 select NEED_PER_CPU_EMBED_FIRST_CHUNK 303 select NEED_PER_CPU_PAGE_FIRST_CHUNK 304 select NEED_SG_DMA_LENGTH 305 select NUMA_MEMBLKS if NUMA 306 select PCI_DOMAINS if PCI 307 select PCI_LOCKLESS_CONFIG if PCI 308 select PERF_EVENTS 309 select RTC_LIB 310 select RTC_MC146818_LIB 311 select SPARSE_IRQ 312 select SYSCTL_EXCEPTION_TRACE 313 select THREAD_INFO_IN_TASK 314 select TRACE_IRQFLAGS_SUPPORT 315 select TRACE_IRQFLAGS_NMI_SUPPORT 316 select USER_STACKTRACE_SUPPORT 317 select HAVE_ARCH_KCSAN if X86_64 318 select PROC_PID_ARCH_STATUS if PROC_FS 319 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 320 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 321 select FUNCTION_ALIGNMENT_4B 322 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 323 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 324 325config INSTRUCTION_DECODER 326 def_bool y 327 depends on KPROBES || PERF_EVENTS || UPROBES 328 329config OUTPUT_FORMAT 330 string 331 default "elf32-i386" if X86_32 332 default "elf64-x86-64" if X86_64 333 334config LOCKDEP_SUPPORT 335 def_bool y 336 337config STACKTRACE_SUPPORT 338 def_bool y 339 340config MMU 341 def_bool y 342 343config ARCH_MMAP_RND_BITS_MIN 344 default 28 if 64BIT 345 default 8 346 347config ARCH_MMAP_RND_BITS_MAX 348 default 32 if 64BIT 349 default 16 350 351config ARCH_MMAP_RND_COMPAT_BITS_MIN 352 default 8 353 354config ARCH_MMAP_RND_COMPAT_BITS_MAX 355 default 16 356 357config SBUS 358 bool 359 360config GENERIC_ISA_DMA 361 def_bool y 362 depends on ISA_DMA_API 363 364config GENERIC_CSUM 365 bool 366 default y if KMSAN || KASAN 367 368config GENERIC_BUG 369 def_bool y 370 depends on BUG 371 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 372 373config GENERIC_BUG_RELATIVE_POINTERS 374 bool 375 376config ARCH_MAY_HAVE_PC_FDC 377 def_bool y 378 depends on ISA_DMA_API 379 380config GENERIC_CALIBRATE_DELAY 381 def_bool y 382 383config ARCH_HAS_CPU_RELAX 384 def_bool y 385 386config ARCH_HIBERNATION_POSSIBLE 387 def_bool y 388 389config ARCH_SUSPEND_POSSIBLE 390 def_bool y 391 392config AUDIT_ARCH 393 def_bool y if X86_64 394 395config KASAN_SHADOW_OFFSET 396 hex 397 depends on KASAN 398 default 0xdffffc0000000000 399 400config HAVE_INTEL_TXT 401 def_bool y 402 depends on INTEL_IOMMU && ACPI 403 404config X86_64_SMP 405 def_bool y 406 depends on X86_64 && SMP 407 408config ARCH_SUPPORTS_UPROBES 409 def_bool y 410 411config FIX_EARLYCON_MEM 412 def_bool y 413 414config DYNAMIC_PHYSICAL_MASK 415 bool 416 417config PGTABLE_LEVELS 418 int 419 default 5 if X86_5LEVEL 420 default 4 if X86_64 421 default 3 if X86_PAE 422 default 2 423 424config CC_HAS_SANE_STACKPROTECTOR 425 bool 426 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 427 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 428 help 429 We have to make sure stack protector is unconditionally disabled if 430 the compiler produces broken code or if it does not let us control 431 the segment on 32-bit kernels. 432 433menu "Processor type and features" 434 435config SMP 436 bool "Symmetric multi-processing support" 437 help 438 This enables support for systems with more than one CPU. If you have 439 a system with only one CPU, say N. If you have a system with more 440 than one CPU, say Y. 441 442 If you say N here, the kernel will run on uni- and multiprocessor 443 machines, but will use only one CPU of a multiprocessor machine. If 444 you say Y here, the kernel will run on many, but not all, 445 uniprocessor machines. On a uniprocessor machine, the kernel 446 will run faster if you say N here. 447 448 Note that if you say Y here and choose architecture "586" or 449 "Pentium" under "Processor family", the kernel will not work on 486 450 architectures. Similarly, multiprocessor kernels for the "PPro" 451 architecture may not work on all Pentium based boards. 452 453 People using multiprocessor machines who say Y here should also say 454 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 455 Management" code will be disabled if you say Y here. 456 457 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 458 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 459 <http://www.tldp.org/docs.html#howto>. 460 461 If you don't know what to do here, say N. 462 463config X86_X2APIC 464 bool "Support x2apic" 465 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 466 help 467 This enables x2apic support on CPUs that have this feature. 468 469 This allows 32-bit apic IDs (so it can support very large systems), 470 and accesses the local apic via MSRs not via mmio. 471 472 Some Intel systems circa 2022 and later are locked into x2APIC mode 473 and can not fall back to the legacy APIC modes if SGX or TDX are 474 enabled in the BIOS. They will boot with very reduced functionality 475 without enabling this option. 476 477 If you don't know what to do here, say N. 478 479config X86_POSTED_MSI 480 bool "Enable MSI and MSI-x delivery by posted interrupts" 481 depends on X86_64 && IRQ_REMAP 482 help 483 This enables MSIs that are under interrupt remapping to be delivered as 484 posted interrupts to the host kernel. Interrupt throughput can 485 potentially be improved by coalescing CPU notifications during high 486 frequency bursts. 487 488 If you don't know what to do here, say N. 489 490config X86_MPPARSE 491 bool "Enable MPS table" if ACPI 492 default y 493 depends on X86_LOCAL_APIC 494 help 495 For old smp systems that do not have proper acpi support. Newer systems 496 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 497 498config X86_CPU_RESCTRL 499 bool "x86 CPU resource control support" 500 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 501 select KERNFS 502 select PROC_CPU_RESCTRL if PROC_FS 503 help 504 Enable x86 CPU resource control support. 505 506 Provide support for the allocation and monitoring of system resources 507 usage by the CPU. 508 509 Intel calls this Intel Resource Director Technology 510 (Intel(R) RDT). More information about RDT can be found in the 511 Intel x86 Architecture Software Developer Manual. 512 513 AMD calls this AMD Platform Quality of Service (AMD QoS). 514 More information about AMD QoS can be found in the AMD64 Technology 515 Platform Quality of Service Extensions manual. 516 517 Say N if unsure. 518 519config X86_FRED 520 bool "Flexible Return and Event Delivery" 521 depends on X86_64 522 help 523 When enabled, try to use Flexible Return and Event Delivery 524 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 525 ring transitions and exception/interrupt handling if the 526 system supports it. 527 528config X86_BIGSMP 529 bool "Support for big SMP systems with more than 8 CPUs" 530 depends on SMP && X86_32 531 help 532 This option is needed for the systems that have more than 8 CPUs. 533 534config X86_EXTENDED_PLATFORM 535 bool "Support for extended (non-PC) x86 platforms" 536 default y 537 help 538 If you disable this option then the kernel will only support 539 standard PC platforms. (which covers the vast majority of 540 systems out there.) 541 542 If you enable this option then you'll be able to select support 543 for the following non-PC x86 platforms, depending on the value of 544 CONFIG_64BIT. 545 546 32-bit platforms (CONFIG_64BIT=n): 547 Goldfish (Android emulator) 548 AMD Elan 549 RDC R-321x SoC 550 SGI 320/540 (Visual Workstation) 551 STA2X11-based (e.g. Northville) 552 Moorestown MID devices 553 554 64-bit platforms (CONFIG_64BIT=y): 555 Numascale NumaChip 556 ScaleMP vSMP 557 SGI Ultraviolet 558 559 If you have one of these systems, or if you want to build a 560 generic distribution kernel, say Y here - otherwise say N. 561 562# This is an alphabetically sorted list of 64 bit extended platforms 563# Please maintain the alphabetic order if and when there are additions 564config X86_NUMACHIP 565 bool "Numascale NumaChip" 566 depends on X86_64 567 depends on X86_EXTENDED_PLATFORM 568 depends on NUMA 569 depends on SMP 570 depends on X86_X2APIC 571 depends on PCI_MMCONFIG 572 help 573 Adds support for Numascale NumaChip large-SMP systems. Needed to 574 enable more than ~168 cores. 575 If you don't have one of these, you should say N here. 576 577config X86_VSMP 578 bool "ScaleMP vSMP" 579 select HYPERVISOR_GUEST 580 select PARAVIRT 581 depends on X86_64 && PCI 582 depends on X86_EXTENDED_PLATFORM 583 depends on SMP 584 help 585 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 586 supposed to run on these EM64T-based machines. Only choose this option 587 if you have one of these machines. 588 589config X86_UV 590 bool "SGI Ultraviolet" 591 depends on X86_64 592 depends on X86_EXTENDED_PLATFORM 593 depends on NUMA 594 depends on EFI 595 depends on KEXEC_CORE 596 depends on X86_X2APIC 597 depends on PCI 598 help 599 This option is needed in order to support SGI Ultraviolet systems. 600 If you don't have one of these, you should say N here. 601 602# Following is an alphabetically sorted list of 32 bit extended platforms 603# Please maintain the alphabetic order if and when there are additions 604 605config X86_GOLDFISH 606 bool "Goldfish (Virtual Platform)" 607 depends on X86_EXTENDED_PLATFORM 608 help 609 Enable support for the Goldfish virtual platform used primarily 610 for Android development. Unless you are building for the Android 611 Goldfish emulator say N here. 612 613config X86_INTEL_CE 614 bool "CE4100 TV platform" 615 depends on PCI 616 depends on PCI_GODIRECT 617 depends on X86_IO_APIC 618 depends on X86_32 619 depends on X86_EXTENDED_PLATFORM 620 select X86_REBOOTFIXUPS 621 select OF 622 select OF_EARLY_FLATTREE 623 help 624 Select for the Intel CE media processor (CE4100) SOC. 625 This option compiles in support for the CE4100 SOC for settop 626 boxes and media devices. 627 628config X86_INTEL_MID 629 bool "Intel MID platform support" 630 depends on X86_EXTENDED_PLATFORM 631 depends on X86_PLATFORM_DEVICES 632 depends on PCI 633 depends on X86_64 || (PCI_GOANY && X86_32) 634 depends on X86_IO_APIC 635 select I2C 636 select DW_APB_TIMER 637 select INTEL_SCU_PCI 638 help 639 Select to build a kernel capable of supporting Intel MID (Mobile 640 Internet Device) platform systems which do not have the PCI legacy 641 interfaces. If you are building for a PC class system say N here. 642 643 Intel MID platforms are based on an Intel processor and chipset which 644 consume less power than most of the x86 derivatives. 645 646config X86_INTEL_QUARK 647 bool "Intel Quark platform support" 648 depends on X86_32 649 depends on X86_EXTENDED_PLATFORM 650 depends on X86_PLATFORM_DEVICES 651 depends on X86_TSC 652 depends on PCI 653 depends on PCI_GOANY 654 depends on X86_IO_APIC 655 select IOSF_MBI 656 select INTEL_IMR 657 select COMMON_CLK 658 help 659 Select to include support for Quark X1000 SoC. 660 Say Y here if you have a Quark based system such as the Arduino 661 compatible Intel Galileo. 662 663config X86_INTEL_LPSS 664 bool "Intel Low Power Subsystem Support" 665 depends on X86 && ACPI && PCI 666 select COMMON_CLK 667 select PINCTRL 668 select IOSF_MBI 669 help 670 Select to build support for Intel Low Power Subsystem such as 671 found on Intel Lynxpoint PCH. Selecting this option enables 672 things like clock tree (common clock framework) and pincontrol 673 which are needed by the LPSS peripheral drivers. 674 675config X86_AMD_PLATFORM_DEVICE 676 bool "AMD ACPI2Platform devices support" 677 depends on ACPI 678 select COMMON_CLK 679 select PINCTRL 680 help 681 Select to interpret AMD specific ACPI device to platform device 682 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 683 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 684 implemented under PINCTRL subsystem. 685 686config IOSF_MBI 687 tristate "Intel SoC IOSF Sideband support for SoC platforms" 688 depends on PCI 689 help 690 This option enables sideband register access support for Intel SoC 691 platforms. On these platforms the IOSF sideband is used in lieu of 692 MSR's for some register accesses, mostly but not limited to thermal 693 and power. Drivers may query the availability of this device to 694 determine if they need the sideband in order to work on these 695 platforms. The sideband is available on the following SoC products. 696 This list is not meant to be exclusive. 697 - BayTrail 698 - Braswell 699 - Quark 700 701 You should say Y if you are running a kernel on one of these SoC's. 702 703config IOSF_MBI_DEBUG 704 bool "Enable IOSF sideband access through debugfs" 705 depends on IOSF_MBI && DEBUG_FS 706 help 707 Select this option to expose the IOSF sideband access registers (MCR, 708 MDR, MCRX) through debugfs to write and read register information from 709 different units on the SoC. This is most useful for obtaining device 710 state information for debug and analysis. As this is a general access 711 mechanism, users of this option would have specific knowledge of the 712 device they want to access. 713 714 If you don't require the option or are in doubt, say N. 715 716config X86_RDC321X 717 bool "RDC R-321x SoC" 718 depends on X86_32 719 depends on X86_EXTENDED_PLATFORM 720 select M486 721 select X86_REBOOTFIXUPS 722 help 723 This option is needed for RDC R-321x system-on-chip, also known 724 as R-8610-(G). 725 If you don't have one of these chips, you should say N here. 726 727config X86_32_NON_STANDARD 728 bool "Support non-standard 32-bit SMP architectures" 729 depends on X86_32 && SMP 730 depends on X86_EXTENDED_PLATFORM 731 help 732 This option compiles in the bigsmp and STA2X11 default 733 subarchitectures. It is intended for a generic binary 734 kernel. If you select them all, kernel will probe it one by 735 one and will fallback to default. 736 737# Alphabetically sorted list of Non standard 32 bit platforms 738 739config X86_SUPPORTS_MEMORY_FAILURE 740 def_bool y 741 # MCE code calls memory_failure(): 742 depends on X86_MCE 743 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 744 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 745 depends on X86_64 || !SPARSEMEM 746 select ARCH_SUPPORTS_MEMORY_FAILURE 747 748config STA2X11 749 bool "STA2X11 Companion Chip Support" 750 depends on X86_32_NON_STANDARD && PCI 751 select SWIOTLB 752 select MFD_STA2X11 753 select GPIOLIB 754 help 755 This adds support for boards based on the STA2X11 IO-Hub, 756 a.k.a. "ConneXt". The chip is used in place of the standard 757 PC chipset, so all "standard" peripherals are missing. If this 758 option is selected the kernel will still be able to boot on 759 standard PC machines. 760 761config X86_32_IRIS 762 tristate "Eurobraille/Iris poweroff module" 763 depends on X86_32 764 help 765 The Iris machines from EuroBraille do not have APM or ACPI support 766 to shut themselves down properly. A special I/O sequence is 767 needed to do so, which is what this module does at 768 kernel shutdown. 769 770 This is only for Iris machines from EuroBraille. 771 772 If unused, say N. 773 774config SCHED_OMIT_FRAME_POINTER 775 def_bool y 776 prompt "Single-depth WCHAN output" 777 depends on X86 778 help 779 Calculate simpler /proc/<PID>/wchan values. If this option 780 is disabled then wchan values will recurse back to the 781 caller function. This provides more accurate wchan values, 782 at the expense of slightly more scheduling overhead. 783 784 If in doubt, say "Y". 785 786menuconfig HYPERVISOR_GUEST 787 bool "Linux guest support" 788 help 789 Say Y here to enable options for running Linux under various hyper- 790 visors. This option enables basic hypervisor detection and platform 791 setup. 792 793 If you say N, all options in this submenu will be skipped and 794 disabled, and Linux guest support won't be built in. 795 796if HYPERVISOR_GUEST 797 798config PARAVIRT 799 bool "Enable paravirtualization code" 800 depends on HAVE_STATIC_CALL 801 help 802 This changes the kernel so it can modify itself when it is run 803 under a hypervisor, potentially improving performance significantly 804 over full virtualization. However, when run without a hypervisor 805 the kernel is theoretically slower and slightly larger. 806 807config PARAVIRT_XXL 808 bool 809 810config PARAVIRT_DEBUG 811 bool "paravirt-ops debugging" 812 depends on PARAVIRT && DEBUG_KERNEL 813 help 814 Enable to debug paravirt_ops internals. Specifically, BUG if 815 a paravirt_op is missing when it is called. 816 817config PARAVIRT_SPINLOCKS 818 bool "Paravirtualization layer for spinlocks" 819 depends on PARAVIRT && SMP 820 help 821 Paravirtualized spinlocks allow a pvops backend to replace the 822 spinlock implementation with something virtualization-friendly 823 (for example, block the virtual CPU rather than spinning). 824 825 It has a minimal impact on native kernels and gives a nice performance 826 benefit on paravirtualized KVM / Xen kernels. 827 828 If you are unsure how to answer this question, answer Y. 829 830config X86_HV_CALLBACK_VECTOR 831 def_bool n 832 833source "arch/x86/xen/Kconfig" 834 835config KVM_GUEST 836 bool "KVM Guest support (including kvmclock)" 837 depends on PARAVIRT 838 select PARAVIRT_CLOCK 839 select ARCH_CPUIDLE_HALTPOLL 840 select X86_HV_CALLBACK_VECTOR 841 default y 842 help 843 This option enables various optimizations for running under the KVM 844 hypervisor. It includes a paravirtualized clock, so that instead 845 of relying on a PIT (or probably other) emulation by the 846 underlying device model, the host provides the guest with 847 timing infrastructure such as time of day, and system time 848 849config ARCH_CPUIDLE_HALTPOLL 850 def_bool n 851 prompt "Disable host haltpoll when loading haltpoll driver" 852 help 853 If virtualized under KVM, disable host haltpoll. 854 855config PVH 856 bool "Support for running PVH guests" 857 help 858 This option enables the PVH entry point for guest virtual machines 859 as specified in the x86/HVM direct boot ABI. 860 861config PARAVIRT_TIME_ACCOUNTING 862 bool "Paravirtual steal time accounting" 863 depends on PARAVIRT 864 help 865 Select this option to enable fine granularity task steal time 866 accounting. Time spent executing other tasks in parallel with 867 the current vCPU is discounted from the vCPU power. To account for 868 that, there can be a small performance impact. 869 870 If in doubt, say N here. 871 872config PARAVIRT_CLOCK 873 bool 874 875config JAILHOUSE_GUEST 876 bool "Jailhouse non-root cell support" 877 depends on X86_64 && PCI 878 select X86_PM_TIMER 879 help 880 This option allows to run Linux as guest in a Jailhouse non-root 881 cell. You can leave this option disabled if you only want to start 882 Jailhouse and run Linux afterwards in the root cell. 883 884config ACRN_GUEST 885 bool "ACRN Guest support" 886 depends on X86_64 887 select X86_HV_CALLBACK_VECTOR 888 help 889 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 890 a flexible, lightweight reference open-source hypervisor, built with 891 real-time and safety-criticality in mind. It is built for embedded 892 IOT with small footprint and real-time features. More details can be 893 found in https://projectacrn.org/. 894 895config INTEL_TDX_GUEST 896 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 897 depends on X86_64 && CPU_SUP_INTEL 898 depends on X86_X2APIC 899 depends on EFI_STUB 900 select ARCH_HAS_CC_PLATFORM 901 select X86_MEM_ENCRYPT 902 select X86_MCE 903 select UNACCEPTED_MEMORY 904 help 905 Support running as a guest under Intel TDX. Without this support, 906 the guest kernel can not boot or run under TDX. 907 TDX includes memory encryption and integrity capabilities 908 which protect the confidentiality and integrity of guest 909 memory contents and CPU state. TDX guests are protected from 910 some attacks from the VMM. 911 912endif # HYPERVISOR_GUEST 913 914source "arch/x86/Kconfig.cpu" 915 916config HPET_TIMER 917 def_bool X86_64 918 prompt "HPET Timer Support" if X86_32 919 help 920 Use the IA-PC HPET (High Precision Event Timer) to manage 921 time in preference to the PIT and RTC, if a HPET is 922 present. 923 HPET is the next generation timer replacing legacy 8254s. 924 The HPET provides a stable time base on SMP 925 systems, unlike the TSC, but it is more expensive to access, 926 as it is off-chip. The interface used is documented 927 in the HPET spec, revision 1. 928 929 You can safely choose Y here. However, HPET will only be 930 activated if the platform and the BIOS support this feature. 931 Otherwise the 8254 will be used for timing services. 932 933 Choose N to continue using the legacy 8254 timer. 934 935config HPET_EMULATE_RTC 936 def_bool y 937 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 938 939# Mark as expert because too many people got it wrong. 940# The code disables itself when not needed. 941config DMI 942 default y 943 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 944 bool "Enable DMI scanning" if EXPERT 945 help 946 Enabled scanning of DMI to identify machine quirks. Say Y 947 here unless you have verified that your setup is not 948 affected by entries in the DMI blacklist. Required by PNP 949 BIOS code. 950 951config GART_IOMMU 952 bool "Old AMD GART IOMMU support" 953 select IOMMU_HELPER 954 select SWIOTLB 955 depends on X86_64 && PCI && AMD_NB 956 help 957 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 958 GART based hardware IOMMUs. 959 960 The GART supports full DMA access for devices with 32-bit access 961 limitations, on systems with more than 3 GB. This is usually needed 962 for USB, sound, many IDE/SATA chipsets and some other devices. 963 964 Newer systems typically have a modern AMD IOMMU, supported via 965 the CONFIG_AMD_IOMMU=y config option. 966 967 In normal configurations this driver is only active when needed: 968 there's more than 3 GB of memory and the system contains a 969 32-bit limited device. 970 971 If unsure, say Y. 972 973config BOOT_VESA_SUPPORT 974 bool 975 help 976 If true, at least one selected framebuffer driver can take advantage 977 of VESA video modes set at an early boot stage via the vga= parameter. 978 979config MAXSMP 980 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 981 depends on X86_64 && SMP && DEBUG_KERNEL 982 select CPUMASK_OFFSTACK 983 help 984 Enable maximum number of CPUS and NUMA Nodes for this architecture. 985 If unsure, say N. 986 987# 988# The maximum number of CPUs supported: 989# 990# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 991# and which can be configured interactively in the 992# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 993# 994# The ranges are different on 32-bit and 64-bit kernels, depending on 995# hardware capabilities and scalability features of the kernel. 996# 997# ( If MAXSMP is enabled we just use the highest possible value and disable 998# interactive configuration. ) 999# 1000 1001config NR_CPUS_RANGE_BEGIN 1002 int 1003 default NR_CPUS_RANGE_END if MAXSMP 1004 default 1 if !SMP 1005 default 2 1006 1007config NR_CPUS_RANGE_END 1008 int 1009 depends on X86_32 1010 default 64 if SMP && X86_BIGSMP 1011 default 8 if SMP && !X86_BIGSMP 1012 default 1 if !SMP 1013 1014config NR_CPUS_RANGE_END 1015 int 1016 depends on X86_64 1017 default 8192 if SMP && CPUMASK_OFFSTACK 1018 default 512 if SMP && !CPUMASK_OFFSTACK 1019 default 1 if !SMP 1020 1021config NR_CPUS_DEFAULT 1022 int 1023 depends on X86_32 1024 default 32 if X86_BIGSMP 1025 default 8 if SMP 1026 default 1 if !SMP 1027 1028config NR_CPUS_DEFAULT 1029 int 1030 depends on X86_64 1031 default 8192 if MAXSMP 1032 default 64 if SMP 1033 default 1 if !SMP 1034 1035config NR_CPUS 1036 int "Maximum number of CPUs" if SMP && !MAXSMP 1037 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1038 default NR_CPUS_DEFAULT 1039 help 1040 This allows you to specify the maximum number of CPUs which this 1041 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1042 supported value is 8192, otherwise the maximum value is 512. The 1043 minimum value which makes sense is 2. 1044 1045 This is purely to save memory: each supported CPU adds about 8KB 1046 to the kernel image. 1047 1048config SCHED_CLUSTER 1049 bool "Cluster scheduler support" 1050 depends on SMP 1051 default y 1052 help 1053 Cluster scheduler support improves the CPU scheduler's decision 1054 making when dealing with machines that have clusters of CPUs. 1055 Cluster usually means a couple of CPUs which are placed closely 1056 by sharing mid-level caches, last-level cache tags or internal 1057 busses. 1058 1059config SCHED_SMT 1060 def_bool y if SMP 1061 1062config SCHED_MC 1063 def_bool y 1064 prompt "Multi-core scheduler support" 1065 depends on SMP 1066 help 1067 Multi-core scheduler support improves the CPU scheduler's decision 1068 making when dealing with multi-core CPU chips at a cost of slightly 1069 increased overhead in some places. If unsure say N here. 1070 1071config SCHED_MC_PRIO 1072 bool "CPU core priorities scheduler support" 1073 depends on SCHED_MC 1074 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1075 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1076 select CPU_FREQ 1077 default y 1078 help 1079 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1080 core ordering determined at manufacturing time, which allows 1081 certain cores to reach higher turbo frequencies (when running 1082 single threaded workloads) than others. 1083 1084 Enabling this kernel feature teaches the scheduler about 1085 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1086 scheduler's CPU selection logic accordingly, so that higher 1087 overall system performance can be achieved. 1088 1089 This feature will have no effect on CPUs without this feature. 1090 1091 If unsure say Y here. 1092 1093config UP_LATE_INIT 1094 def_bool y 1095 depends on !SMP && X86_LOCAL_APIC 1096 1097config X86_UP_APIC 1098 bool "Local APIC support on uniprocessors" if !PCI_MSI 1099 default PCI_MSI 1100 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1101 help 1102 A local APIC (Advanced Programmable Interrupt Controller) is an 1103 integrated interrupt controller in the CPU. If you have a single-CPU 1104 system which has a processor with a local APIC, you can say Y here to 1105 enable and use it. If you say Y here even though your machine doesn't 1106 have a local APIC, then the kernel will still run with no slowdown at 1107 all. The local APIC supports CPU-generated self-interrupts (timer, 1108 performance counters), and the NMI watchdog which detects hard 1109 lockups. 1110 1111config X86_UP_IOAPIC 1112 bool "IO-APIC support on uniprocessors" 1113 depends on X86_UP_APIC 1114 help 1115 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1116 SMP-capable replacement for PC-style interrupt controllers. Most 1117 SMP systems and many recent uniprocessor systems have one. 1118 1119 If you have a single-CPU system with an IO-APIC, you can say Y here 1120 to use it. If you say Y here even though your machine doesn't have 1121 an IO-APIC, then the kernel will still run with no slowdown at all. 1122 1123config X86_LOCAL_APIC 1124 def_bool y 1125 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1126 select IRQ_DOMAIN_HIERARCHY 1127 1128config ACPI_MADT_WAKEUP 1129 def_bool y 1130 depends on X86_64 1131 depends on ACPI 1132 depends on SMP 1133 depends on X86_LOCAL_APIC 1134 1135config X86_IO_APIC 1136 def_bool y 1137 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1138 1139config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1140 bool "Reroute for broken boot IRQs" 1141 depends on X86_IO_APIC 1142 help 1143 This option enables a workaround that fixes a source of 1144 spurious interrupts. This is recommended when threaded 1145 interrupt handling is used on systems where the generation of 1146 superfluous "boot interrupts" cannot be disabled. 1147 1148 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1149 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1150 kernel does during interrupt handling). On chipsets where this 1151 boot IRQ generation cannot be disabled, this workaround keeps 1152 the original IRQ line masked so that only the equivalent "boot 1153 IRQ" is delivered to the CPUs. The workaround also tells the 1154 kernel to set up the IRQ handler on the boot IRQ line. In this 1155 way only one interrupt is delivered to the kernel. Otherwise 1156 the spurious second interrupt may cause the kernel to bring 1157 down (vital) interrupt lines. 1158 1159 Only affects "broken" chipsets. Interrupt sharing may be 1160 increased on these systems. 1161 1162config X86_MCE 1163 bool "Machine Check / overheating reporting" 1164 select GENERIC_ALLOCATOR 1165 default y 1166 help 1167 Machine Check support allows the processor to notify the 1168 kernel if it detects a problem (e.g. overheating, data corruption). 1169 The action the kernel takes depends on the severity of the problem, 1170 ranging from warning messages to halting the machine. 1171 1172config X86_MCELOG_LEGACY 1173 bool "Support for deprecated /dev/mcelog character device" 1174 depends on X86_MCE 1175 help 1176 Enable support for /dev/mcelog which is needed by the old mcelog 1177 userspace logging daemon. Consider switching to the new generation 1178 rasdaemon solution. 1179 1180config X86_MCE_INTEL 1181 def_bool y 1182 prompt "Intel MCE features" 1183 depends on X86_MCE && X86_LOCAL_APIC 1184 help 1185 Additional support for intel specific MCE features such as 1186 the thermal monitor. 1187 1188config X86_MCE_AMD 1189 def_bool y 1190 prompt "AMD MCE features" 1191 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1192 help 1193 Additional support for AMD specific MCE features such as 1194 the DRAM Error Threshold. 1195 1196config X86_ANCIENT_MCE 1197 bool "Support for old Pentium 5 / WinChip machine checks" 1198 depends on X86_32 && X86_MCE 1199 help 1200 Include support for machine check handling on old Pentium 5 or WinChip 1201 systems. These typically need to be enabled explicitly on the command 1202 line. 1203 1204config X86_MCE_THRESHOLD 1205 depends on X86_MCE_AMD || X86_MCE_INTEL 1206 def_bool y 1207 1208config X86_MCE_INJECT 1209 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1210 tristate "Machine check injector support" 1211 help 1212 Provide support for injecting machine checks for testing purposes. 1213 If you don't know what a machine check is and you don't do kernel 1214 QA it is safe to say n. 1215 1216source "arch/x86/events/Kconfig" 1217 1218config X86_LEGACY_VM86 1219 bool "Legacy VM86 support" 1220 depends on X86_32 1221 help 1222 This option allows user programs to put the CPU into V8086 1223 mode, which is an 80286-era approximation of 16-bit real mode. 1224 1225 Some very old versions of X and/or vbetool require this option 1226 for user mode setting. Similarly, DOSEMU will use it if 1227 available to accelerate real mode DOS programs. However, any 1228 recent version of DOSEMU, X, or vbetool should be fully 1229 functional even without kernel VM86 support, as they will all 1230 fall back to software emulation. Nevertheless, if you are using 1231 a 16-bit DOS program where 16-bit performance matters, vm86 1232 mode might be faster than emulation and you might want to 1233 enable this option. 1234 1235 Note that any app that works on a 64-bit kernel is unlikely to 1236 need this option, as 64-bit kernels don't, and can't, support 1237 V8086 mode. This option is also unrelated to 16-bit protected 1238 mode and is not needed to run most 16-bit programs under Wine. 1239 1240 Enabling this option increases the complexity of the kernel 1241 and slows down exception handling a tiny bit. 1242 1243 If unsure, say N here. 1244 1245config VM86 1246 bool 1247 default X86_LEGACY_VM86 1248 1249config X86_16BIT 1250 bool "Enable support for 16-bit segments" if EXPERT 1251 default y 1252 depends on MODIFY_LDT_SYSCALL 1253 help 1254 This option is required by programs like Wine to run 16-bit 1255 protected mode legacy code on x86 processors. Disabling 1256 this option saves about 300 bytes on i386, or around 6K text 1257 plus 16K runtime memory on x86-64, 1258 1259config X86_ESPFIX32 1260 def_bool y 1261 depends on X86_16BIT && X86_32 1262 1263config X86_ESPFIX64 1264 def_bool y 1265 depends on X86_16BIT && X86_64 1266 1267config X86_VSYSCALL_EMULATION 1268 bool "Enable vsyscall emulation" if EXPERT 1269 default y 1270 depends on X86_64 1271 help 1272 This enables emulation of the legacy vsyscall page. Disabling 1273 it is roughly equivalent to booting with vsyscall=none, except 1274 that it will also disable the helpful warning if a program 1275 tries to use a vsyscall. With this option set to N, offending 1276 programs will just segfault, citing addresses of the form 1277 0xffffffffff600?00. 1278 1279 This option is required by many programs built before 2013, and 1280 care should be used even with newer programs if set to N. 1281 1282 Disabling this option saves about 7K of kernel size and 1283 possibly 4K of additional runtime pagetable memory. 1284 1285config X86_IOPL_IOPERM 1286 bool "IOPERM and IOPL Emulation" 1287 default y 1288 help 1289 This enables the ioperm() and iopl() syscalls which are necessary 1290 for legacy applications. 1291 1292 Legacy IOPL support is an overbroad mechanism which allows user 1293 space aside of accessing all 65536 I/O ports also to disable 1294 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1295 capabilities and permission from potentially active security 1296 modules. 1297 1298 The emulation restricts the functionality of the syscall to 1299 only allowing the full range I/O port access, but prevents the 1300 ability to disable interrupts from user space which would be 1301 granted if the hardware IOPL mechanism would be used. 1302 1303config TOSHIBA 1304 tristate "Toshiba Laptop support" 1305 depends on X86_32 1306 help 1307 This adds a driver to safely access the System Management Mode of 1308 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1309 not work on models with a Phoenix BIOS. The System Management Mode 1310 is used to set the BIOS and power saving options on Toshiba portables. 1311 1312 For information on utilities to make use of this driver see the 1313 Toshiba Linux utilities web site at: 1314 <http://www.buzzard.org.uk/toshiba/>. 1315 1316 Say Y if you intend to run this kernel on a Toshiba portable. 1317 Say N otherwise. 1318 1319config X86_REBOOTFIXUPS 1320 bool "Enable X86 board specific fixups for reboot" 1321 depends on X86_32 1322 help 1323 This enables chipset and/or board specific fixups to be done 1324 in order to get reboot to work correctly. This is only needed on 1325 some combinations of hardware and BIOS. The symptom, for which 1326 this config is intended, is when reboot ends with a stalled/hung 1327 system. 1328 1329 Currently, the only fixup is for the Geode machines using 1330 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1331 1332 Say Y if you want to enable the fixup. Currently, it's safe to 1333 enable this option even if you don't need it. 1334 Say N otherwise. 1335 1336config MICROCODE 1337 def_bool y 1338 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1339 1340config MICROCODE_INITRD32 1341 def_bool y 1342 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1343 1344config MICROCODE_LATE_LOADING 1345 bool "Late microcode loading (DANGEROUS)" 1346 default n 1347 depends on MICROCODE && SMP 1348 help 1349 Loading microcode late, when the system is up and executing instructions 1350 is a tricky business and should be avoided if possible. Just the sequence 1351 of synchronizing all cores and SMT threads is one fragile dance which does 1352 not guarantee that cores might not softlock after the loading. Therefore, 1353 use this at your own risk. Late loading taints the kernel unless the 1354 microcode header indicates that it is safe for late loading via the 1355 minimal revision check. This minimal revision check can be enforced on 1356 the kernel command line with "microcode.minrev=Y". 1357 1358config MICROCODE_LATE_FORCE_MINREV 1359 bool "Enforce late microcode loading minimal revision check" 1360 default n 1361 depends on MICROCODE_LATE_LOADING 1362 help 1363 To prevent that users load microcode late which modifies already 1364 in use features, newer microcode patches have a minimum revision field 1365 in the microcode header, which tells the kernel which minimum 1366 revision must be active in the CPU to safely load that new microcode 1367 late into the running system. If disabled the check will not 1368 be enforced but the kernel will be tainted when the minimal 1369 revision check fails. 1370 1371 This minimal revision check can also be controlled via the 1372 "microcode.minrev" parameter on the kernel command line. 1373 1374 If unsure say Y. 1375 1376config X86_MSR 1377 tristate "/dev/cpu/*/msr - Model-specific register support" 1378 help 1379 This device gives privileged processes access to the x86 1380 Model-Specific Registers (MSRs). It is a character device with 1381 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1382 MSR accesses are directed to a specific CPU on multi-processor 1383 systems. 1384 1385config X86_CPUID 1386 tristate "/dev/cpu/*/cpuid - CPU information support" 1387 help 1388 This device gives processes access to the x86 CPUID instruction to 1389 be executed on a specific processor. It is a character device 1390 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1391 /dev/cpu/31/cpuid. 1392 1393choice 1394 prompt "High Memory Support" 1395 default HIGHMEM4G 1396 depends on X86_32 1397 1398config NOHIGHMEM 1399 bool "off" 1400 help 1401 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1402 However, the address space of 32-bit x86 processors is only 4 1403 Gigabytes large. That means that, if you have a large amount of 1404 physical memory, not all of it can be "permanently mapped" by the 1405 kernel. The physical memory that's not permanently mapped is called 1406 "high memory". 1407 1408 If you are compiling a kernel which will never run on a machine with 1409 more than 1 Gigabyte total physical RAM, answer "off" here (default 1410 choice and suitable for most users). This will result in a "3GB/1GB" 1411 split: 3GB are mapped so that each process sees a 3GB virtual memory 1412 space and the remaining part of the 4GB virtual memory space is used 1413 by the kernel to permanently map as much physical memory as 1414 possible. 1415 1416 If the machine has between 1 and 4 Gigabytes physical RAM, then 1417 answer "4GB" here. 1418 1419 If more than 4 Gigabytes is used then answer "64GB" here. This 1420 selection turns Intel PAE (Physical Address Extension) mode on. 1421 PAE implements 3-level paging on IA32 processors. PAE is fully 1422 supported by Linux, PAE mode is implemented on all recent Intel 1423 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1424 then the kernel will not boot on CPUs that don't support PAE! 1425 1426 The actual amount of total physical memory will either be 1427 auto detected or can be forced by using a kernel command line option 1428 such as "mem=256M". (Try "man bootparam" or see the documentation of 1429 your boot loader (lilo or loadlin) about how to pass options to the 1430 kernel at boot time.) 1431 1432 If unsure, say "off". 1433 1434config HIGHMEM4G 1435 bool "4GB" 1436 help 1437 Select this if you have a 32-bit processor and between 1 and 4 1438 gigabytes of physical RAM. 1439 1440config HIGHMEM64G 1441 bool "64GB" 1442 depends on X86_HAVE_PAE 1443 select X86_PAE 1444 help 1445 Select this if you have a 32-bit processor and more than 4 1446 gigabytes of physical RAM. 1447 1448endchoice 1449 1450choice 1451 prompt "Memory split" if EXPERT 1452 default VMSPLIT_3G 1453 depends on X86_32 1454 help 1455 Select the desired split between kernel and user memory. 1456 1457 If the address range available to the kernel is less than the 1458 physical memory installed, the remaining memory will be available 1459 as "high memory". Accessing high memory is a little more costly 1460 than low memory, as it needs to be mapped into the kernel first. 1461 Note that increasing the kernel address space limits the range 1462 available to user programs, making the address space there 1463 tighter. Selecting anything other than the default 3G/1G split 1464 will also likely make your kernel incompatible with binary-only 1465 kernel modules. 1466 1467 If you are not absolutely sure what you are doing, leave this 1468 option alone! 1469 1470 config VMSPLIT_3G 1471 bool "3G/1G user/kernel split" 1472 config VMSPLIT_3G_OPT 1473 depends on !X86_PAE 1474 bool "3G/1G user/kernel split (for full 1G low memory)" 1475 config VMSPLIT_2G 1476 bool "2G/2G user/kernel split" 1477 config VMSPLIT_2G_OPT 1478 depends on !X86_PAE 1479 bool "2G/2G user/kernel split (for full 2G low memory)" 1480 config VMSPLIT_1G 1481 bool "1G/3G user/kernel split" 1482endchoice 1483 1484config PAGE_OFFSET 1485 hex 1486 default 0xB0000000 if VMSPLIT_3G_OPT 1487 default 0x80000000 if VMSPLIT_2G 1488 default 0x78000000 if VMSPLIT_2G_OPT 1489 default 0x40000000 if VMSPLIT_1G 1490 default 0xC0000000 1491 depends on X86_32 1492 1493config HIGHMEM 1494 def_bool y 1495 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1496 1497config X86_PAE 1498 bool "PAE (Physical Address Extension) Support" 1499 depends on X86_32 && X86_HAVE_PAE 1500 select PHYS_ADDR_T_64BIT 1501 select SWIOTLB 1502 help 1503 PAE is required for NX support, and furthermore enables 1504 larger swapspace support for non-overcommit purposes. It 1505 has the cost of more pagetable lookup overhead, and also 1506 consumes more pagetable space per process. 1507 1508config X86_5LEVEL 1509 bool "Enable 5-level page tables support" 1510 default y 1511 select DYNAMIC_MEMORY_LAYOUT 1512 select SPARSEMEM_VMEMMAP 1513 depends on X86_64 1514 help 1515 5-level paging enables access to larger address space: 1516 up to 128 PiB of virtual address space and 4 PiB of 1517 physical address space. 1518 1519 It will be supported by future Intel CPUs. 1520 1521 A kernel with the option enabled can be booted on machines that 1522 support 4- or 5-level paging. 1523 1524 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1525 information. 1526 1527 Say N if unsure. 1528 1529config X86_DIRECT_GBPAGES 1530 def_bool y 1531 depends on X86_64 1532 help 1533 Certain kernel features effectively disable kernel 1534 linear 1 GB mappings (even if the CPU otherwise 1535 supports them), so don't confuse the user by printing 1536 that we have them enabled. 1537 1538config X86_CPA_STATISTICS 1539 bool "Enable statistic for Change Page Attribute" 1540 depends on DEBUG_FS 1541 help 1542 Expose statistics about the Change Page Attribute mechanism, which 1543 helps to determine the effectiveness of preserving large and huge 1544 page mappings when mapping protections are changed. 1545 1546config X86_MEM_ENCRYPT 1547 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1548 select DYNAMIC_PHYSICAL_MASK 1549 def_bool n 1550 1551config AMD_MEM_ENCRYPT 1552 bool "AMD Secure Memory Encryption (SME) support" 1553 depends on X86_64 && CPU_SUP_AMD 1554 depends on EFI_STUB 1555 select DMA_COHERENT_POOL 1556 select ARCH_USE_MEMREMAP_PROT 1557 select INSTRUCTION_DECODER 1558 select ARCH_HAS_CC_PLATFORM 1559 select X86_MEM_ENCRYPT 1560 select UNACCEPTED_MEMORY 1561 help 1562 Say yes to enable support for the encryption of system memory. 1563 This requires an AMD processor that supports Secure Memory 1564 Encryption (SME). 1565 1566# Common NUMA Features 1567config NUMA 1568 bool "NUMA Memory Allocation and Scheduler Support" 1569 depends on SMP 1570 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1571 default y if X86_BIGSMP 1572 select USE_PERCPU_NUMA_NODE_ID 1573 select OF_NUMA if OF 1574 help 1575 Enable NUMA (Non-Uniform Memory Access) support. 1576 1577 The kernel will try to allocate memory used by a CPU on the 1578 local memory controller of the CPU and add some more 1579 NUMA awareness to the kernel. 1580 1581 For 64-bit this is recommended if the system is Intel Core i7 1582 (or later), AMD Opteron, or EM64T NUMA. 1583 1584 For 32-bit this is only needed if you boot a 32-bit 1585 kernel on a 64-bit NUMA platform. 1586 1587 Otherwise, you should say N. 1588 1589config AMD_NUMA 1590 def_bool y 1591 prompt "Old style AMD Opteron NUMA detection" 1592 depends on X86_64 && NUMA && PCI 1593 help 1594 Enable AMD NUMA node topology detection. You should say Y here if 1595 you have a multi processor AMD system. This uses an old method to 1596 read the NUMA configuration directly from the builtin Northbridge 1597 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1598 which also takes priority if both are compiled in. 1599 1600config X86_64_ACPI_NUMA 1601 def_bool y 1602 prompt "ACPI NUMA detection" 1603 depends on X86_64 && NUMA && ACPI && PCI 1604 select ACPI_NUMA 1605 help 1606 Enable ACPI SRAT based node topology detection. 1607 1608config NODES_SHIFT 1609 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1610 range 1 10 1611 default "10" if MAXSMP 1612 default "6" if X86_64 1613 default "3" 1614 depends on NUMA 1615 help 1616 Specify the maximum number of NUMA Nodes available on the target 1617 system. Increases memory reserved to accommodate various tables. 1618 1619config ARCH_FLATMEM_ENABLE 1620 def_bool y 1621 depends on X86_32 && !NUMA 1622 1623config ARCH_SPARSEMEM_ENABLE 1624 def_bool y 1625 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1626 select SPARSEMEM_STATIC if X86_32 1627 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1628 1629config ARCH_SPARSEMEM_DEFAULT 1630 def_bool X86_64 || (NUMA && X86_32) 1631 1632config ARCH_SELECT_MEMORY_MODEL 1633 def_bool y 1634 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1635 1636config ARCH_MEMORY_PROBE 1637 bool "Enable sysfs memory/probe interface" 1638 depends on MEMORY_HOTPLUG 1639 help 1640 This option enables a sysfs memory/probe interface for testing. 1641 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1642 If you are unsure how to answer this question, answer N. 1643 1644config ARCH_PROC_KCORE_TEXT 1645 def_bool y 1646 depends on X86_64 && PROC_KCORE 1647 1648config ILLEGAL_POINTER_VALUE 1649 hex 1650 default 0 if X86_32 1651 default 0xdead000000000000 if X86_64 1652 1653config X86_PMEM_LEGACY_DEVICE 1654 bool 1655 1656config X86_PMEM_LEGACY 1657 tristate "Support non-standard NVDIMMs and ADR protected memory" 1658 depends on PHYS_ADDR_T_64BIT 1659 depends on BLK_DEV 1660 select X86_PMEM_LEGACY_DEVICE 1661 select NUMA_KEEP_MEMINFO if NUMA 1662 select LIBNVDIMM 1663 help 1664 Treat memory marked using the non-standard e820 type of 12 as used 1665 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1666 The kernel will offer these regions to the 'pmem' driver so 1667 they can be used for persistent storage. 1668 1669 Say Y if unsure. 1670 1671config HIGHPTE 1672 bool "Allocate 3rd-level pagetables from highmem" 1673 depends on HIGHMEM 1674 help 1675 The VM uses one page table entry for each page of physical memory. 1676 For systems with a lot of RAM, this can be wasteful of precious 1677 low memory. Setting this option will put user-space page table 1678 entries in high memory. 1679 1680config X86_CHECK_BIOS_CORRUPTION 1681 bool "Check for low memory corruption" 1682 help 1683 Periodically check for memory corruption in low memory, which 1684 is suspected to be caused by BIOS. Even when enabled in the 1685 configuration, it is disabled at runtime. Enable it by 1686 setting "memory_corruption_check=1" on the kernel command 1687 line. By default it scans the low 64k of memory every 60 1688 seconds; see the memory_corruption_check_size and 1689 memory_corruption_check_period parameters in 1690 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1691 1692 When enabled with the default parameters, this option has 1693 almost no overhead, as it reserves a relatively small amount 1694 of memory and scans it infrequently. It both detects corruption 1695 and prevents it from affecting the running system. 1696 1697 It is, however, intended as a diagnostic tool; if repeatable 1698 BIOS-originated corruption always affects the same memory, 1699 you can use memmap= to prevent the kernel from using that 1700 memory. 1701 1702config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1703 bool "Set the default setting of memory_corruption_check" 1704 depends on X86_CHECK_BIOS_CORRUPTION 1705 default y 1706 help 1707 Set whether the default state of memory_corruption_check is 1708 on or off. 1709 1710config MATH_EMULATION 1711 bool 1712 depends on MODIFY_LDT_SYSCALL 1713 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1714 help 1715 Linux can emulate a math coprocessor (used for floating point 1716 operations) if you don't have one. 486DX and Pentium processors have 1717 a math coprocessor built in, 486SX and 386 do not, unless you added 1718 a 487DX or 387, respectively. (The messages during boot time can 1719 give you some hints here ["man dmesg"].) Everyone needs either a 1720 coprocessor or this emulation. 1721 1722 If you don't have a math coprocessor, you need to say Y here; if you 1723 say Y here even though you have a coprocessor, the coprocessor will 1724 be used nevertheless. (This behavior can be changed with the kernel 1725 command line option "no387", which comes handy if your coprocessor 1726 is broken. Try "man bootparam" or see the documentation of your boot 1727 loader (lilo or loadlin) about how to pass options to the kernel at 1728 boot time.) This means that it is a good idea to say Y here if you 1729 intend to use this kernel on different machines. 1730 1731 More information about the internals of the Linux math coprocessor 1732 emulation can be found in <file:arch/x86/math-emu/README>. 1733 1734 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1735 kernel, it won't hurt. 1736 1737config MTRR 1738 def_bool y 1739 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1740 help 1741 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1742 the Memory Type Range Registers (MTRRs) may be used to control 1743 processor access to memory ranges. This is most useful if you have 1744 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1745 allows bus write transfers to be combined into a larger transfer 1746 before bursting over the PCI/AGP bus. This can increase performance 1747 of image write operations 2.5 times or more. Saying Y here creates a 1748 /proc/mtrr file which may be used to manipulate your processor's 1749 MTRRs. Typically the X server should use this. 1750 1751 This code has a reasonably generic interface so that similar 1752 control registers on other processors can be easily supported 1753 as well: 1754 1755 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1756 Registers (ARRs) which provide a similar functionality to MTRRs. For 1757 these, the ARRs are used to emulate the MTRRs. 1758 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1759 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1760 write-combining. All of these processors are supported by this code 1761 and it makes sense to say Y here if you have one of them. 1762 1763 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1764 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1765 can lead to all sorts of problems, so it's good to say Y here. 1766 1767 You can safely say Y even if your machine doesn't have MTRRs, you'll 1768 just add about 9 KB to your kernel. 1769 1770 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1771 1772config MTRR_SANITIZER 1773 def_bool y 1774 prompt "MTRR cleanup support" 1775 depends on MTRR 1776 help 1777 Convert MTRR layout from continuous to discrete, so X drivers can 1778 add writeback entries. 1779 1780 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1781 The largest mtrr entry size for a continuous block can be set with 1782 mtrr_chunk_size. 1783 1784 If unsure, say Y. 1785 1786config MTRR_SANITIZER_ENABLE_DEFAULT 1787 int "MTRR cleanup enable value (0-1)" 1788 range 0 1 1789 default "0" 1790 depends on MTRR_SANITIZER 1791 help 1792 Enable mtrr cleanup default value 1793 1794config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1795 int "MTRR cleanup spare reg num (0-7)" 1796 range 0 7 1797 default "1" 1798 depends on MTRR_SANITIZER 1799 help 1800 mtrr cleanup spare entries default, it can be changed via 1801 mtrr_spare_reg_nr=N on the kernel command line. 1802 1803config X86_PAT 1804 def_bool y 1805 prompt "x86 PAT support" if EXPERT 1806 depends on MTRR 1807 select ARCH_USES_PG_ARCH_2 1808 help 1809 Use PAT attributes to setup page level cache control. 1810 1811 PATs are the modern equivalents of MTRRs and are much more 1812 flexible than MTRRs. 1813 1814 Say N here if you see bootup problems (boot crash, boot hang, 1815 spontaneous reboots) or a non-working video driver. 1816 1817 If unsure, say Y. 1818 1819config X86_UMIP 1820 def_bool y 1821 prompt "User Mode Instruction Prevention" if EXPERT 1822 help 1823 User Mode Instruction Prevention (UMIP) is a security feature in 1824 some x86 processors. If enabled, a general protection fault is 1825 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1826 executed in user mode. These instructions unnecessarily expose 1827 information about the hardware state. 1828 1829 The vast majority of applications do not use these instructions. 1830 For the very few that do, software emulation is provided in 1831 specific cases in protected and virtual-8086 modes. Emulated 1832 results are dummy. 1833 1834config CC_HAS_IBT 1835 # GCC >= 9 and binutils >= 2.29 1836 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1837 # Clang/LLVM >= 14 1838 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1839 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1840 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1841 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1842 $(as-instr,endbr64) 1843 1844config X86_CET 1845 def_bool n 1846 help 1847 CET features configured (Shadow stack or IBT) 1848 1849config X86_KERNEL_IBT 1850 prompt "Indirect Branch Tracking" 1851 def_bool y 1852 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1853 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1854 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1855 select OBJTOOL 1856 select X86_CET 1857 help 1858 Build the kernel with support for Indirect Branch Tracking, a 1859 hardware support course-grain forward-edge Control Flow Integrity 1860 protection. It enforces that all indirect calls must land on 1861 an ENDBR instruction, as such, the compiler will instrument the 1862 code with them to make this happen. 1863 1864 In addition to building the kernel with IBT, seal all functions that 1865 are not indirect call targets, avoiding them ever becoming one. 1866 1867 This requires LTO like objtool runs and will slow down the build. It 1868 does significantly reduce the number of ENDBR instructions in the 1869 kernel image. 1870 1871config X86_INTEL_MEMORY_PROTECTION_KEYS 1872 prompt "Memory Protection Keys" 1873 def_bool y 1874 # Note: only available in 64-bit mode 1875 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1876 select ARCH_USES_HIGH_VMA_FLAGS 1877 select ARCH_HAS_PKEYS 1878 help 1879 Memory Protection Keys provides a mechanism for enforcing 1880 page-based protections, but without requiring modification of the 1881 page tables when an application changes protection domains. 1882 1883 For details, see Documentation/core-api/protection-keys.rst 1884 1885 If unsure, say y. 1886 1887config ARCH_PKEY_BITS 1888 int 1889 default 4 1890 1891choice 1892 prompt "TSX enable mode" 1893 depends on CPU_SUP_INTEL 1894 default X86_INTEL_TSX_MODE_OFF 1895 help 1896 Intel's TSX (Transactional Synchronization Extensions) feature 1897 allows to optimize locking protocols through lock elision which 1898 can lead to a noticeable performance boost. 1899 1900 On the other hand it has been shown that TSX can be exploited 1901 to form side channel attacks (e.g. TAA) and chances are there 1902 will be more of those attacks discovered in the future. 1903 1904 Therefore TSX is not enabled by default (aka tsx=off). An admin 1905 might override this decision by tsx=on the command line parameter. 1906 Even with TSX enabled, the kernel will attempt to enable the best 1907 possible TAA mitigation setting depending on the microcode available 1908 for the particular machine. 1909 1910 This option allows to set the default tsx mode between tsx=on, =off 1911 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1912 details. 1913 1914 Say off if not sure, auto if TSX is in use but it should be used on safe 1915 platforms or on if TSX is in use and the security aspect of tsx is not 1916 relevant. 1917 1918config X86_INTEL_TSX_MODE_OFF 1919 bool "off" 1920 help 1921 TSX is disabled if possible - equals to tsx=off command line parameter. 1922 1923config X86_INTEL_TSX_MODE_ON 1924 bool "on" 1925 help 1926 TSX is always enabled on TSX capable HW - equals the tsx=on command 1927 line parameter. 1928 1929config X86_INTEL_TSX_MODE_AUTO 1930 bool "auto" 1931 help 1932 TSX is enabled on TSX capable HW that is believed to be safe against 1933 side channel attacks- equals the tsx=auto command line parameter. 1934endchoice 1935 1936config X86_SGX 1937 bool "Software Guard eXtensions (SGX)" 1938 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1939 depends on CRYPTO=y 1940 depends on CRYPTO_SHA256=y 1941 select MMU_NOTIFIER 1942 select NUMA_KEEP_MEMINFO if NUMA 1943 select XARRAY_MULTI 1944 help 1945 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1946 that can be used by applications to set aside private regions of code 1947 and data, referred to as enclaves. An enclave's private memory can 1948 only be accessed by code running within the enclave. Accesses from 1949 outside the enclave, including other enclaves, are disallowed by 1950 hardware. 1951 1952 If unsure, say N. 1953 1954config X86_USER_SHADOW_STACK 1955 bool "X86 userspace shadow stack" 1956 depends on AS_WRUSS 1957 depends on X86_64 1958 select ARCH_USES_HIGH_VMA_FLAGS 1959 select X86_CET 1960 help 1961 Shadow stack protection is a hardware feature that detects function 1962 return address corruption. This helps mitigate ROP attacks. 1963 Applications must be enabled to use it, and old userspace does not 1964 get protection "for free". 1965 1966 CPUs supporting shadow stacks were first released in 2020. 1967 1968 See Documentation/arch/x86/shstk.rst for more information. 1969 1970 If unsure, say N. 1971 1972config INTEL_TDX_HOST 1973 bool "Intel Trust Domain Extensions (TDX) host support" 1974 depends on CPU_SUP_INTEL 1975 depends on X86_64 1976 depends on KVM_INTEL 1977 depends on X86_X2APIC 1978 select ARCH_KEEP_MEMBLOCK 1979 depends on CONTIG_ALLOC 1980 depends on !KEXEC_CORE 1981 depends on X86_MCE 1982 help 1983 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1984 host and certain physical attacks. This option enables necessary TDX 1985 support in the host kernel to run confidential VMs. 1986 1987 If unsure, say N. 1988 1989config EFI 1990 bool "EFI runtime service support" 1991 depends on ACPI 1992 select UCS2_STRING 1993 select EFI_RUNTIME_WRAPPERS 1994 select ARCH_USE_MEMREMAP_PROT 1995 select EFI_RUNTIME_MAP if KEXEC_CORE 1996 help 1997 This enables the kernel to use EFI runtime services that are 1998 available (such as the EFI variable services). 1999 2000 This option is only useful on systems that have EFI firmware. 2001 In addition, you should use the latest ELILO loader available 2002 at <http://elilo.sourceforge.net> in order to take advantage 2003 of EFI runtime services. However, even with this option, the 2004 resultant kernel should continue to boot on existing non-EFI 2005 platforms. 2006 2007config EFI_STUB 2008 bool "EFI stub support" 2009 depends on EFI 2010 select RELOCATABLE 2011 help 2012 This kernel feature allows a bzImage to be loaded directly 2013 by EFI firmware without the use of a bootloader. 2014 2015 See Documentation/admin-guide/efi-stub.rst for more information. 2016 2017config EFI_HANDOVER_PROTOCOL 2018 bool "EFI handover protocol (DEPRECATED)" 2019 depends on EFI_STUB 2020 default y 2021 help 2022 Select this in order to include support for the deprecated EFI 2023 handover protocol, which defines alternative entry points into the 2024 EFI stub. This is a practice that has no basis in the UEFI 2025 specification, and requires a priori knowledge on the part of the 2026 bootloader about Linux/x86 specific ways of passing the command line 2027 and initrd, and where in memory those assets may be loaded. 2028 2029 If in doubt, say Y. Even though the corresponding support is not 2030 present in upstream GRUB or other bootloaders, most distros build 2031 GRUB with numerous downstream patches applied, and may rely on the 2032 handover protocol as as result. 2033 2034config EFI_MIXED 2035 bool "EFI mixed-mode support" 2036 depends on EFI_STUB && X86_64 2037 help 2038 Enabling this feature allows a 64-bit kernel to be booted 2039 on a 32-bit firmware, provided that your CPU supports 64-bit 2040 mode. 2041 2042 Note that it is not possible to boot a mixed-mode enabled 2043 kernel via the EFI boot stub - a bootloader that supports 2044 the EFI handover protocol must be used. 2045 2046 If unsure, say N. 2047 2048config EFI_RUNTIME_MAP 2049 bool "Export EFI runtime maps to sysfs" if EXPERT 2050 depends on EFI 2051 help 2052 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2053 That memory map is required by the 2nd kernel to set up EFI virtual 2054 mappings after kexec, but can also be used for debugging purposes. 2055 2056 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2057 2058source "kernel/Kconfig.hz" 2059 2060config ARCH_SUPPORTS_KEXEC 2061 def_bool y 2062 2063config ARCH_SUPPORTS_KEXEC_FILE 2064 def_bool X86_64 2065 2066config ARCH_SELECTS_KEXEC_FILE 2067 def_bool y 2068 depends on KEXEC_FILE 2069 select HAVE_IMA_KEXEC if IMA 2070 2071config ARCH_SUPPORTS_KEXEC_PURGATORY 2072 def_bool y 2073 2074config ARCH_SUPPORTS_KEXEC_SIG 2075 def_bool y 2076 2077config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2078 def_bool y 2079 2080config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2081 def_bool y 2082 2083config ARCH_SUPPORTS_KEXEC_JUMP 2084 def_bool y 2085 2086config ARCH_SUPPORTS_CRASH_DUMP 2087 def_bool X86_64 || (X86_32 && HIGHMEM) 2088 2089config ARCH_SUPPORTS_CRASH_HOTPLUG 2090 def_bool y 2091 2092config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2093 def_bool CRASH_RESERVE 2094 2095config PHYSICAL_START 2096 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2097 default "0x1000000" 2098 help 2099 This gives the physical address where the kernel is loaded. 2100 2101 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2102 will decompress itself to above physical address and run from there. 2103 Otherwise, bzImage will run from the address where it has been loaded 2104 by the boot loader. The only exception is if it is loaded below the 2105 above physical address, in which case it will relocate itself there. 2106 2107 In normal kdump cases one does not have to set/change this option 2108 as now bzImage can be compiled as a completely relocatable image 2109 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2110 address. This option is mainly useful for the folks who don't want 2111 to use a bzImage for capturing the crash dump and want to use a 2112 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2113 to be specifically compiled to run from a specific memory area 2114 (normally a reserved region) and this option comes handy. 2115 2116 So if you are using bzImage for capturing the crash dump, 2117 leave the value here unchanged to 0x1000000 and set 2118 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2119 for capturing the crash dump change this value to start of 2120 the reserved region. In other words, it can be set based on 2121 the "X" value as specified in the "crashkernel=YM@XM" 2122 command line boot parameter passed to the panic-ed 2123 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2124 for more details about crash dumps. 2125 2126 Usage of bzImage for capturing the crash dump is recommended as 2127 one does not have to build two kernels. Same kernel can be used 2128 as production kernel and capture kernel. Above option should have 2129 gone away after relocatable bzImage support is introduced. But it 2130 is present because there are users out there who continue to use 2131 vmlinux for dump capture. This option should go away down the 2132 line. 2133 2134 Don't change this unless you know what you are doing. 2135 2136config RELOCATABLE 2137 bool "Build a relocatable kernel" 2138 default y 2139 help 2140 This builds a kernel image that retains relocation information 2141 so it can be loaded someplace besides the default 1MB. 2142 The relocations tend to make the kernel binary about 10% larger, 2143 but are discarded at runtime. 2144 2145 One use is for the kexec on panic case where the recovery kernel 2146 must live at a different physical address than the primary 2147 kernel. 2148 2149 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2150 it has been loaded at and the compile time physical address 2151 (CONFIG_PHYSICAL_START) is used as the minimum location. 2152 2153config RANDOMIZE_BASE 2154 bool "Randomize the address of the kernel image (KASLR)" 2155 depends on RELOCATABLE 2156 default y 2157 help 2158 In support of Kernel Address Space Layout Randomization (KASLR), 2159 this randomizes the physical address at which the kernel image 2160 is decompressed and the virtual address where the kernel 2161 image is mapped, as a security feature that deters exploit 2162 attempts relying on knowledge of the location of kernel 2163 code internals. 2164 2165 On 64-bit, the kernel physical and virtual addresses are 2166 randomized separately. The physical address will be anywhere 2167 between 16MB and the top of physical memory (up to 64TB). The 2168 virtual address will be randomized from 16MB up to 1GB (9 bits 2169 of entropy). Note that this also reduces the memory space 2170 available to kernel modules from 1.5GB to 1GB. 2171 2172 On 32-bit, the kernel physical and virtual addresses are 2173 randomized together. They will be randomized from 16MB up to 2174 512MB (8 bits of entropy). 2175 2176 Entropy is generated using the RDRAND instruction if it is 2177 supported. If RDTSC is supported, its value is mixed into 2178 the entropy pool as well. If neither RDRAND nor RDTSC are 2179 supported, then entropy is read from the i8254 timer. The 2180 usable entropy is limited by the kernel being built using 2181 2GB addressing, and that PHYSICAL_ALIGN must be at a 2182 minimum of 2MB. As a result, only 10 bits of entropy are 2183 theoretically possible, but the implementations are further 2184 limited due to memory layouts. 2185 2186 If unsure, say Y. 2187 2188# Relocation on x86 needs some additional build support 2189config X86_NEED_RELOCS 2190 def_bool y 2191 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2192 2193config PHYSICAL_ALIGN 2194 hex "Alignment value to which kernel should be aligned" 2195 default "0x200000" 2196 range 0x2000 0x1000000 if X86_32 2197 range 0x200000 0x1000000 if X86_64 2198 help 2199 This value puts the alignment restrictions on physical address 2200 where kernel is loaded and run from. Kernel is compiled for an 2201 address which meets above alignment restriction. 2202 2203 If bootloader loads the kernel at a non-aligned address and 2204 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2205 address aligned to above value and run from there. 2206 2207 If bootloader loads the kernel at a non-aligned address and 2208 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2209 load address and decompress itself to the address it has been 2210 compiled for and run from there. The address for which kernel is 2211 compiled already meets above alignment restrictions. Hence the 2212 end result is that kernel runs from a physical address meeting 2213 above alignment restrictions. 2214 2215 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2216 this value must be a multiple of 0x200000. 2217 2218 Don't change this unless you know what you are doing. 2219 2220config DYNAMIC_MEMORY_LAYOUT 2221 bool 2222 help 2223 This option makes base addresses of vmalloc and vmemmap as well as 2224 __PAGE_OFFSET movable during boot. 2225 2226config RANDOMIZE_MEMORY 2227 bool "Randomize the kernel memory sections" 2228 depends on X86_64 2229 depends on RANDOMIZE_BASE 2230 select DYNAMIC_MEMORY_LAYOUT 2231 default RANDOMIZE_BASE 2232 help 2233 Randomizes the base virtual address of kernel memory sections 2234 (physical memory mapping, vmalloc & vmemmap). This security feature 2235 makes exploits relying on predictable memory locations less reliable. 2236 2237 The order of allocations remains unchanged. Entropy is generated in 2238 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2239 configuration have in average 30,000 different possible virtual 2240 addresses for each memory section. 2241 2242 If unsure, say Y. 2243 2244config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2245 hex "Physical memory mapping padding" if EXPERT 2246 depends on RANDOMIZE_MEMORY 2247 default "0xa" if MEMORY_HOTPLUG 2248 default "0x0" 2249 range 0x1 0x40 if MEMORY_HOTPLUG 2250 range 0x0 0x40 2251 help 2252 Define the padding in terabytes added to the existing physical 2253 memory size during kernel memory randomization. It is useful 2254 for memory hotplug support but reduces the entropy available for 2255 address randomization. 2256 2257 If unsure, leave at the default value. 2258 2259config ADDRESS_MASKING 2260 bool "Linear Address Masking support" 2261 depends on X86_64 2262 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2263 help 2264 Linear Address Masking (LAM) modifies the checking that is applied 2265 to 64-bit linear addresses, allowing software to use of the 2266 untranslated address bits for metadata. 2267 2268 The capability can be used for efficient address sanitizers (ASAN) 2269 implementation and for optimizations in JITs. 2270 2271config HOTPLUG_CPU 2272 def_bool y 2273 depends on SMP 2274 2275config COMPAT_VDSO 2276 def_bool n 2277 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2278 depends on COMPAT_32 2279 help 2280 Certain buggy versions of glibc will crash if they are 2281 presented with a 32-bit vDSO that is not mapped at the address 2282 indicated in its segment table. 2283 2284 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2285 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2286 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2287 the only released version with the bug, but OpenSUSE 9 2288 contains a buggy "glibc 2.3.2". 2289 2290 The symptom of the bug is that everything crashes on startup, saying: 2291 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2292 2293 Saying Y here changes the default value of the vdso32 boot 2294 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2295 This works around the glibc bug but hurts performance. 2296 2297 If unsure, say N: if you are compiling your own kernel, you 2298 are unlikely to be using a buggy version of glibc. 2299 2300choice 2301 prompt "vsyscall table for legacy applications" 2302 depends on X86_64 2303 default LEGACY_VSYSCALL_XONLY 2304 help 2305 Legacy user code that does not know how to find the vDSO expects 2306 to be able to issue three syscalls by calling fixed addresses in 2307 kernel space. Since this location is not randomized with ASLR, 2308 it can be used to assist security vulnerability exploitation. 2309 2310 This setting can be changed at boot time via the kernel command 2311 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2312 is deprecated and can only be enabled using the kernel command 2313 line. 2314 2315 On a system with recent enough glibc (2.14 or newer) and no 2316 static binaries, you can say None without a performance penalty 2317 to improve security. 2318 2319 If unsure, select "Emulate execution only". 2320 2321 config LEGACY_VSYSCALL_XONLY 2322 bool "Emulate execution only" 2323 help 2324 The kernel traps and emulates calls into the fixed vsyscall 2325 address mapping and does not allow reads. This 2326 configuration is recommended when userspace might use the 2327 legacy vsyscall area but support for legacy binary 2328 instrumentation of legacy code is not needed. It mitigates 2329 certain uses of the vsyscall area as an ASLR-bypassing 2330 buffer. 2331 2332 config LEGACY_VSYSCALL_NONE 2333 bool "None" 2334 help 2335 There will be no vsyscall mapping at all. This will 2336 eliminate any risk of ASLR bypass due to the vsyscall 2337 fixed address mapping. Attempts to use the vsyscalls 2338 will be reported to dmesg, so that either old or 2339 malicious userspace programs can be identified. 2340 2341endchoice 2342 2343config CMDLINE_BOOL 2344 bool "Built-in kernel command line" 2345 help 2346 Allow for specifying boot arguments to the kernel at 2347 build time. On some systems (e.g. embedded ones), it is 2348 necessary or convenient to provide some or all of the 2349 kernel boot arguments with the kernel itself (that is, 2350 to not rely on the boot loader to provide them.) 2351 2352 To compile command line arguments into the kernel, 2353 set this option to 'Y', then fill in the 2354 boot arguments in CONFIG_CMDLINE. 2355 2356 Systems with fully functional boot loaders (i.e. non-embedded) 2357 should leave this option set to 'N'. 2358 2359config CMDLINE 2360 string "Built-in kernel command string" 2361 depends on CMDLINE_BOOL 2362 default "" 2363 help 2364 Enter arguments here that should be compiled into the kernel 2365 image and used at boot time. If the boot loader provides a 2366 command line at boot time, it is appended to this string to 2367 form the full kernel command line, when the system boots. 2368 2369 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2370 change this behavior. 2371 2372 In most cases, the command line (whether built-in or provided 2373 by the boot loader) should specify the device for the root 2374 file system. 2375 2376config CMDLINE_OVERRIDE 2377 bool "Built-in command line overrides boot loader arguments" 2378 depends on CMDLINE_BOOL && CMDLINE != "" 2379 help 2380 Set this option to 'Y' to have the kernel ignore the boot loader 2381 command line, and use ONLY the built-in command line. 2382 2383 This is used to work around broken boot loaders. This should 2384 be set to 'N' under normal conditions. 2385 2386config MODIFY_LDT_SYSCALL 2387 bool "Enable the LDT (local descriptor table)" if EXPERT 2388 default y 2389 help 2390 Linux can allow user programs to install a per-process x86 2391 Local Descriptor Table (LDT) using the modify_ldt(2) system 2392 call. This is required to run 16-bit or segmented code such as 2393 DOSEMU or some Wine programs. It is also used by some very old 2394 threading libraries. 2395 2396 Enabling this feature adds a small amount of overhead to 2397 context switches and increases the low-level kernel attack 2398 surface. Disabling it removes the modify_ldt(2) system call. 2399 2400 Saying 'N' here may make sense for embedded or server kernels. 2401 2402config STRICT_SIGALTSTACK_SIZE 2403 bool "Enforce strict size checking for sigaltstack" 2404 depends on DYNAMIC_SIGFRAME 2405 help 2406 For historical reasons MINSIGSTKSZ is a constant which became 2407 already too small with AVX512 support. Add a mechanism to 2408 enforce strict checking of the sigaltstack size against the 2409 real size of the FPU frame. This option enables the check 2410 by default. It can also be controlled via the kernel command 2411 line option 'strict_sas_size' independent of this config 2412 switch. Enabling it might break existing applications which 2413 allocate a too small sigaltstack but 'work' because they 2414 never get a signal delivered. 2415 2416 Say 'N' unless you want to really enforce this check. 2417 2418config CFI_AUTO_DEFAULT 2419 bool "Attempt to use FineIBT by default at boot time" 2420 depends on FINEIBT 2421 default y 2422 help 2423 Attempt to use FineIBT by default at boot time. If enabled, 2424 this is the same as booting with "cfi=auto". If disabled, 2425 this is the same as booting with "cfi=kcfi". 2426 2427source "kernel/livepatch/Kconfig" 2428 2429endmenu 2430 2431config CC_HAS_NAMED_AS 2432 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null) 2433 depends on CC_IS_GCC 2434 2435config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2436 def_bool CC_IS_GCC && GCC_VERSION >= 130300 2437 2438config USE_X86_SEG_SUPPORT 2439 def_bool y 2440 depends on CC_HAS_NAMED_AS 2441 # 2442 # -fsanitize=kernel-address (KASAN) and -fsanitize=thread 2443 # (KCSAN) are incompatible with named address spaces with 2444 # GCC < 13.3 - see GCC PR sanitizer/111736. 2445 # 2446 depends on !(KASAN || KCSAN) || CC_HAS_NAMED_AS_FIXED_SANITIZERS 2447 2448config CC_HAS_SLS 2449 def_bool $(cc-option,-mharden-sls=all) 2450 2451config CC_HAS_RETURN_THUNK 2452 def_bool $(cc-option,-mfunction-return=thunk-extern) 2453 2454config CC_HAS_ENTRY_PADDING 2455 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2456 2457config FUNCTION_PADDING_CFI 2458 int 2459 default 59 if FUNCTION_ALIGNMENT_64B 2460 default 27 if FUNCTION_ALIGNMENT_32B 2461 default 11 if FUNCTION_ALIGNMENT_16B 2462 default 3 if FUNCTION_ALIGNMENT_8B 2463 default 0 2464 2465# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2466# except Kconfig can't do arithmetic :/ 2467config FUNCTION_PADDING_BYTES 2468 int 2469 default FUNCTION_PADDING_CFI if CFI_CLANG 2470 default FUNCTION_ALIGNMENT 2471 2472config CALL_PADDING 2473 def_bool n 2474 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2475 select FUNCTION_ALIGNMENT_16B 2476 2477config FINEIBT 2478 def_bool y 2479 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE 2480 select CALL_PADDING 2481 2482config HAVE_CALL_THUNKS 2483 def_bool y 2484 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2485 2486config CALL_THUNKS 2487 def_bool n 2488 select CALL_PADDING 2489 2490config PREFIX_SYMBOLS 2491 def_bool y 2492 depends on CALL_PADDING && !CFI_CLANG 2493 2494menuconfig CPU_MITIGATIONS 2495 bool "Mitigations for CPU vulnerabilities" 2496 default y 2497 help 2498 Say Y here to enable options which enable mitigations for hardware 2499 vulnerabilities (usually related to speculative execution). 2500 Mitigations can be disabled or restricted to SMT systems at runtime 2501 via the "mitigations" kernel parameter. 2502 2503 If you say N, all mitigations will be disabled. This CANNOT be 2504 overridden at runtime. 2505 2506 Say 'Y', unless you really know what you are doing. 2507 2508if CPU_MITIGATIONS 2509 2510config MITIGATION_PAGE_TABLE_ISOLATION 2511 bool "Remove the kernel mapping in user mode" 2512 default y 2513 depends on (X86_64 || X86_PAE) 2514 help 2515 This feature reduces the number of hardware side channels by 2516 ensuring that the majority of kernel addresses are not mapped 2517 into userspace. 2518 2519 See Documentation/arch/x86/pti.rst for more details. 2520 2521config MITIGATION_RETPOLINE 2522 bool "Avoid speculative indirect branches in kernel" 2523 select OBJTOOL if HAVE_OBJTOOL 2524 default y 2525 help 2526 Compile kernel with the retpoline compiler options to guard against 2527 kernel-to-user data leaks by avoiding speculative indirect 2528 branches. Requires a compiler with -mindirect-branch=thunk-extern 2529 support for full protection. The kernel may run slower. 2530 2531config MITIGATION_RETHUNK 2532 bool "Enable return-thunks" 2533 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2534 select OBJTOOL if HAVE_OBJTOOL 2535 default y if X86_64 2536 help 2537 Compile the kernel with the return-thunks compiler option to guard 2538 against kernel-to-user data leaks by avoiding return speculation. 2539 Requires a compiler with -mfunction-return=thunk-extern 2540 support for full protection. The kernel may run slower. 2541 2542config MITIGATION_UNRET_ENTRY 2543 bool "Enable UNRET on kernel entry" 2544 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2545 default y 2546 help 2547 Compile the kernel with support for the retbleed=unret mitigation. 2548 2549config MITIGATION_CALL_DEPTH_TRACKING 2550 bool "Mitigate RSB underflow with call depth tracking" 2551 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2552 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2553 select CALL_THUNKS 2554 default y 2555 help 2556 Compile the kernel with call depth tracking to mitigate the Intel 2557 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2558 mitigation is off by default and needs to be enabled on the 2559 kernel command line via the retbleed=stuff option. For 2560 non-affected systems the overhead of this option is marginal as 2561 the call depth tracking is using run-time generated call thunks 2562 in a compiler generated padding area and call patching. This 2563 increases text size by ~5%. For non affected systems this space 2564 is unused. On affected SKL systems this results in a significant 2565 performance gain over the IBRS mitigation. 2566 2567config CALL_THUNKS_DEBUG 2568 bool "Enable call thunks and call depth tracking debugging" 2569 depends on MITIGATION_CALL_DEPTH_TRACKING 2570 select FUNCTION_ALIGNMENT_32B 2571 default n 2572 help 2573 Enable call/ret counters for imbalance detection and build in 2574 a noisy dmesg about callthunks generation and call patching for 2575 trouble shooting. The debug prints need to be enabled on the 2576 kernel command line with 'debug-callthunks'. 2577 Only enable this when you are debugging call thunks as this 2578 creates a noticeable runtime overhead. If unsure say N. 2579 2580config MITIGATION_IBPB_ENTRY 2581 bool "Enable IBPB on kernel entry" 2582 depends on CPU_SUP_AMD && X86_64 2583 default y 2584 help 2585 Compile the kernel with support for the retbleed=ibpb mitigation. 2586 2587config MITIGATION_IBRS_ENTRY 2588 bool "Enable IBRS on kernel entry" 2589 depends on CPU_SUP_INTEL && X86_64 2590 default y 2591 help 2592 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2593 This mitigates both spectre_v2 and retbleed at great cost to 2594 performance. 2595 2596config MITIGATION_SRSO 2597 bool "Mitigate speculative RAS overflow on AMD" 2598 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2599 default y 2600 help 2601 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2602 2603config MITIGATION_SLS 2604 bool "Mitigate Straight-Line-Speculation" 2605 depends on CC_HAS_SLS && X86_64 2606 select OBJTOOL if HAVE_OBJTOOL 2607 default n 2608 help 2609 Compile the kernel with straight-line-speculation options to guard 2610 against straight line speculation. The kernel image might be slightly 2611 larger. 2612 2613config MITIGATION_GDS 2614 bool "Mitigate Gather Data Sampling" 2615 depends on CPU_SUP_INTEL 2616 default y 2617 help 2618 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware 2619 vulnerability which allows unprivileged speculative access to data 2620 which was previously stored in vector registers. The attacker uses gather 2621 instructions to infer the stale vector register data. 2622 2623config MITIGATION_RFDS 2624 bool "RFDS Mitigation" 2625 depends on CPU_SUP_INTEL 2626 default y 2627 help 2628 Enable mitigation for Register File Data Sampling (RFDS) by default. 2629 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2630 allows unprivileged speculative access to stale data previously 2631 stored in floating point, vector and integer registers. 2632 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2633 2634config MITIGATION_SPECTRE_BHI 2635 bool "Mitigate Spectre-BHB (Branch History Injection)" 2636 depends on CPU_SUP_INTEL 2637 default y 2638 help 2639 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2640 where the branch history buffer is poisoned to speculatively steer 2641 indirect branches. 2642 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2643 2644config MITIGATION_MDS 2645 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug" 2646 depends on CPU_SUP_INTEL 2647 default y 2648 help 2649 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is 2650 a hardware vulnerability which allows unprivileged speculative access 2651 to data which is available in various CPU internal buffers. 2652 See also <file:Documentation/admin-guide/hw-vuln/mds.rst> 2653 2654config MITIGATION_TAA 2655 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug" 2656 depends on CPU_SUP_INTEL 2657 default y 2658 help 2659 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware 2660 vulnerability that allows unprivileged speculative access to data 2661 which is available in various CPU internal buffers by using 2662 asynchronous aborts within an Intel TSX transactional region. 2663 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst> 2664 2665config MITIGATION_MMIO_STALE_DATA 2666 bool "Mitigate MMIO Stale Data hardware bug" 2667 depends on CPU_SUP_INTEL 2668 default y 2669 help 2670 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO 2671 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO) 2672 vulnerabilities that can expose data. The vulnerabilities require the 2673 attacker to have access to MMIO. 2674 See also 2675 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst> 2676 2677config MITIGATION_L1TF 2678 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug" 2679 depends on CPU_SUP_INTEL 2680 default y 2681 help 2682 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a 2683 hardware vulnerability which allows unprivileged speculative access to data 2684 available in the Level 1 Data Cache. 2685 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst 2686 2687config MITIGATION_RETBLEED 2688 bool "Mitigate RETBleed hardware bug" 2689 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY 2690 default y 2691 help 2692 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution 2693 with Return Instructions) vulnerability. RETBleed is a speculative 2694 execution attack which takes advantage of microarchitectural behavior 2695 in many modern microprocessors, similar to Spectre v2. An 2696 unprivileged attacker can use these flaws to bypass conventional 2697 memory security restrictions to gain read access to privileged memory 2698 that would otherwise be inaccessible. 2699 2700config MITIGATION_SPECTRE_V1 2701 bool "Mitigate SPECTRE V1 hardware bug" 2702 default y 2703 help 2704 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a 2705 class of side channel attacks that takes advantage of speculative 2706 execution that bypasses conditional branch instructions used for 2707 memory access bounds check. 2708 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2709 2710config MITIGATION_SPECTRE_V2 2711 bool "Mitigate SPECTRE V2 hardware bug" 2712 default y 2713 help 2714 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre 2715 V2 is a class of side channel attacks that takes advantage of 2716 indirect branch predictors inside the processor. In Spectre variant 2 2717 attacks, the attacker can steer speculative indirect branches in the 2718 victim to gadget code by poisoning the branch target buffer of a CPU 2719 used for predicting indirect branch addresses. 2720 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2721 2722config MITIGATION_SRBDS 2723 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug" 2724 depends on CPU_SUP_INTEL 2725 default y 2726 help 2727 Enable mitigation for Special Register Buffer Data Sampling (SRBDS). 2728 SRBDS is a hardware vulnerability that allows Microarchitectural Data 2729 Sampling (MDS) techniques to infer values returned from special 2730 register accesses. An unprivileged user can extract values returned 2731 from RDRAND and RDSEED executed on another core or sibling thread 2732 using MDS techniques. 2733 See also 2734 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst> 2735 2736config MITIGATION_SSB 2737 bool "Mitigate Speculative Store Bypass (SSB) hardware bug" 2738 default y 2739 help 2740 Enable mitigation for Speculative Store Bypass (SSB). SSB is a 2741 hardware security vulnerability and its exploitation takes advantage 2742 of speculative execution in a similar way to the Meltdown and Spectre 2743 security vulnerabilities. 2744 2745endif 2746 2747config ARCH_HAS_ADD_PAGES 2748 def_bool y 2749 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2750 2751menu "Power management and ACPI options" 2752 2753config ARCH_HIBERNATION_HEADER 2754 def_bool y 2755 depends on HIBERNATION 2756 2757source "kernel/power/Kconfig" 2758 2759source "drivers/acpi/Kconfig" 2760 2761config X86_APM_BOOT 2762 def_bool y 2763 depends on APM 2764 2765menuconfig APM 2766 tristate "APM (Advanced Power Management) BIOS support" 2767 depends on X86_32 && PM_SLEEP 2768 help 2769 APM is a BIOS specification for saving power using several different 2770 techniques. This is mostly useful for battery powered laptops with 2771 APM compliant BIOSes. If you say Y here, the system time will be 2772 reset after a RESUME operation, the /proc/apm device will provide 2773 battery status information, and user-space programs will receive 2774 notification of APM "events" (e.g. battery status change). 2775 2776 If you select "Y" here, you can disable actual use of the APM 2777 BIOS by passing the "apm=off" option to the kernel at boot time. 2778 2779 Note that the APM support is almost completely disabled for 2780 machines with more than one CPU. 2781 2782 In order to use APM, you will need supporting software. For location 2783 and more information, read <file:Documentation/power/apm-acpi.rst> 2784 and the Battery Powered Linux mini-HOWTO, available from 2785 <http://www.tldp.org/docs.html#howto>. 2786 2787 This driver does not spin down disk drives (see the hdparm(8) 2788 manpage ("man 8 hdparm") for that), and it doesn't turn off 2789 VESA-compliant "green" monitors. 2790 2791 This driver does not support the TI 4000M TravelMate and the ACER 2792 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2793 desktop machines also don't have compliant BIOSes, and this driver 2794 may cause those machines to panic during the boot phase. 2795 2796 Generally, if you don't have a battery in your machine, there isn't 2797 much point in using this driver and you should say N. If you get 2798 random kernel OOPSes or reboots that don't seem to be related to 2799 anything, try disabling/enabling this option (or disabling/enabling 2800 APM in your BIOS). 2801 2802 Some other things you should try when experiencing seemingly random, 2803 "weird" problems: 2804 2805 1) make sure that you have enough swap space and that it is 2806 enabled. 2807 2) pass the "idle=poll" option to the kernel 2808 3) switch on floating point emulation in the kernel and pass 2809 the "no387" option to the kernel 2810 4) pass the "floppy=nodma" option to the kernel 2811 5) pass the "mem=4M" option to the kernel (thereby disabling 2812 all but the first 4 MB of RAM) 2813 6) make sure that the CPU is not over clocked. 2814 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2815 8) disable the cache from your BIOS settings 2816 9) install a fan for the video card or exchange video RAM 2817 10) install a better fan for the CPU 2818 11) exchange RAM chips 2819 12) exchange the motherboard. 2820 2821 To compile this driver as a module, choose M here: the 2822 module will be called apm. 2823 2824if APM 2825 2826config APM_IGNORE_USER_SUSPEND 2827 bool "Ignore USER SUSPEND" 2828 help 2829 This option will ignore USER SUSPEND requests. On machines with a 2830 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2831 series notebooks, it is necessary to say Y because of a BIOS bug. 2832 2833config APM_DO_ENABLE 2834 bool "Enable PM at boot time" 2835 help 2836 Enable APM features at boot time. From page 36 of the APM BIOS 2837 specification: "When disabled, the APM BIOS does not automatically 2838 power manage devices, enter the Standby State, enter the Suspend 2839 State, or take power saving steps in response to CPU Idle calls." 2840 This driver will make CPU Idle calls when Linux is idle (unless this 2841 feature is turned off -- see "Do CPU IDLE calls", below). This 2842 should always save battery power, but more complicated APM features 2843 will be dependent on your BIOS implementation. You may need to turn 2844 this option off if your computer hangs at boot time when using APM 2845 support, or if it beeps continuously instead of suspending. Turn 2846 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2847 T400CDT. This is off by default since most machines do fine without 2848 this feature. 2849 2850config APM_CPU_IDLE 2851 depends on CPU_IDLE 2852 bool "Make CPU Idle calls when idle" 2853 help 2854 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2855 On some machines, this can activate improved power savings, such as 2856 a slowed CPU clock rate, when the machine is idle. These idle calls 2857 are made after the idle loop has run for some length of time (e.g., 2858 333 mS). On some machines, this will cause a hang at boot time or 2859 whenever the CPU becomes idle. (On machines with more than one CPU, 2860 this option does nothing.) 2861 2862config APM_DISPLAY_BLANK 2863 bool "Enable console blanking using APM" 2864 help 2865 Enable console blanking using the APM. Some laptops can use this to 2866 turn off the LCD backlight when the screen blanker of the Linux 2867 virtual console blanks the screen. Note that this is only used by 2868 the virtual console screen blanker, and won't turn off the backlight 2869 when using the X Window system. This also doesn't have anything to 2870 do with your VESA-compliant power-saving monitor. Further, this 2871 option doesn't work for all laptops -- it might not turn off your 2872 backlight at all, or it might print a lot of errors to the console, 2873 especially if you are using gpm. 2874 2875config APM_ALLOW_INTS 2876 bool "Allow interrupts during APM BIOS calls" 2877 help 2878 Normally we disable external interrupts while we are making calls to 2879 the APM BIOS as a measure to lessen the effects of a badly behaving 2880 BIOS implementation. The BIOS should reenable interrupts if it 2881 needs to. Unfortunately, some BIOSes do not -- especially those in 2882 many of the newer IBM Thinkpads. If you experience hangs when you 2883 suspend, try setting this to Y. Otherwise, say N. 2884 2885endif # APM 2886 2887source "drivers/cpufreq/Kconfig" 2888 2889source "drivers/cpuidle/Kconfig" 2890 2891source "drivers/idle/Kconfig" 2892 2893endmenu 2894 2895menu "Bus options (PCI etc.)" 2896 2897choice 2898 prompt "PCI access mode" 2899 depends on X86_32 && PCI 2900 default PCI_GOANY 2901 help 2902 On PCI systems, the BIOS can be used to detect the PCI devices and 2903 determine their configuration. However, some old PCI motherboards 2904 have BIOS bugs and may crash if this is done. Also, some embedded 2905 PCI-based systems don't have any BIOS at all. Linux can also try to 2906 detect the PCI hardware directly without using the BIOS. 2907 2908 With this option, you can specify how Linux should detect the 2909 PCI devices. If you choose "BIOS", the BIOS will be used, 2910 if you choose "Direct", the BIOS won't be used, and if you 2911 choose "MMConfig", then PCI Express MMCONFIG will be used. 2912 If you choose "Any", the kernel will try MMCONFIG, then the 2913 direct access method and falls back to the BIOS if that doesn't 2914 work. If unsure, go with the default, which is "Any". 2915 2916config PCI_GOBIOS 2917 bool "BIOS" 2918 2919config PCI_GOMMCONFIG 2920 bool "MMConfig" 2921 2922config PCI_GODIRECT 2923 bool "Direct" 2924 2925config PCI_GOOLPC 2926 bool "OLPC XO-1" 2927 depends on OLPC 2928 2929config PCI_GOANY 2930 bool "Any" 2931 2932endchoice 2933 2934config PCI_BIOS 2935 def_bool y 2936 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2937 2938# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2939config PCI_DIRECT 2940 def_bool y 2941 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2942 2943config PCI_MMCONFIG 2944 bool "Support mmconfig PCI config space access" if X86_64 2945 default y 2946 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2947 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2948 2949config PCI_OLPC 2950 def_bool y 2951 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2952 2953config PCI_XEN 2954 def_bool y 2955 depends on PCI && XEN 2956 2957config MMCONF_FAM10H 2958 def_bool y 2959 depends on X86_64 && PCI_MMCONFIG && ACPI 2960 2961config PCI_CNB20LE_QUIRK 2962 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2963 depends on PCI 2964 help 2965 Read the PCI windows out of the CNB20LE host bridge. This allows 2966 PCI hotplug to work on systems with the CNB20LE chipset which do 2967 not have ACPI. 2968 2969 There's no public spec for this chipset, and this functionality 2970 is known to be incomplete. 2971 2972 You should say N unless you know you need this. 2973 2974config ISA_BUS 2975 bool "ISA bus support on modern systems" if EXPERT 2976 help 2977 Expose ISA bus device drivers and options available for selection and 2978 configuration. Enable this option if your target machine has an ISA 2979 bus. ISA is an older system, displaced by PCI and newer bus 2980 architectures -- if your target machine is modern, it probably does 2981 not have an ISA bus. 2982 2983 If unsure, say N. 2984 2985# x86_64 have no ISA slots, but can have ISA-style DMA. 2986config ISA_DMA_API 2987 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2988 default y 2989 help 2990 Enables ISA-style DMA support for devices requiring such controllers. 2991 If unsure, say Y. 2992 2993if X86_32 2994 2995config ISA 2996 bool "ISA support" 2997 help 2998 Find out whether you have ISA slots on your motherboard. ISA is the 2999 name of a bus system, i.e. the way the CPU talks to the other stuff 3000 inside your box. Other bus systems are PCI, EISA, MicroChannel 3001 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 3002 newer boards don't support it. If you have ISA, say Y, otherwise N. 3003 3004config SCx200 3005 tristate "NatSemi SCx200 support" 3006 help 3007 This provides basic support for National Semiconductor's 3008 (now AMD's) Geode processors. The driver probes for the 3009 PCI-IDs of several on-chip devices, so its a good dependency 3010 for other scx200_* drivers. 3011 3012 If compiled as a module, the driver is named scx200. 3013 3014config SCx200HR_TIMER 3015 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 3016 depends on SCx200 3017 default y 3018 help 3019 This driver provides a clocksource built upon the on-chip 3020 27MHz high-resolution timer. Its also a workaround for 3021 NSC Geode SC-1100's buggy TSC, which loses time when the 3022 processor goes idle (as is done by the scheduler). The 3023 other workaround is idle=poll boot option. 3024 3025config OLPC 3026 bool "One Laptop Per Child support" 3027 depends on !X86_PAE 3028 select GPIOLIB 3029 select OF 3030 select OF_PROMTREE 3031 select IRQ_DOMAIN 3032 select OLPC_EC 3033 help 3034 Add support for detecting the unique features of the OLPC 3035 XO hardware. 3036 3037config OLPC_XO1_PM 3038 bool "OLPC XO-1 Power Management" 3039 depends on OLPC && MFD_CS5535=y && PM_SLEEP 3040 help 3041 Add support for poweroff and suspend of the OLPC XO-1 laptop. 3042 3043config OLPC_XO1_RTC 3044 bool "OLPC XO-1 Real Time Clock" 3045 depends on OLPC_XO1_PM && RTC_DRV_CMOS 3046 help 3047 Add support for the XO-1 real time clock, which can be used as a 3048 programmable wakeup source. 3049 3050config OLPC_XO1_SCI 3051 bool "OLPC XO-1 SCI extras" 3052 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 3053 depends on INPUT=y 3054 select POWER_SUPPLY 3055 help 3056 Add support for SCI-based features of the OLPC XO-1 laptop: 3057 - EC-driven system wakeups 3058 - Power button 3059 - Ebook switch 3060 - Lid switch 3061 - AC adapter status updates 3062 - Battery status updates 3063 3064config OLPC_XO15_SCI 3065 bool "OLPC XO-1.5 SCI extras" 3066 depends on OLPC && ACPI 3067 select POWER_SUPPLY 3068 help 3069 Add support for SCI-based features of the OLPC XO-1.5 laptop: 3070 - EC-driven system wakeups 3071 - AC adapter status updates 3072 - Battery status updates 3073 3074config GEODE_COMMON 3075 bool 3076 3077config ALIX 3078 bool "PCEngines ALIX System Support (LED setup)" 3079 select GPIOLIB 3080 select GEODE_COMMON 3081 help 3082 This option enables system support for the PCEngines ALIX. 3083 At present this just sets up LEDs for GPIO control on 3084 ALIX2/3/6 boards. However, other system specific setup should 3085 get added here. 3086 3087 Note: You must still enable the drivers for GPIO and LED support 3088 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 3089 3090 Note: You have to set alix.force=1 for boards with Award BIOS. 3091 3092config NET5501 3093 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3094 select GPIOLIB 3095 select GEODE_COMMON 3096 help 3097 This option enables system support for the Soekris Engineering net5501. 3098 3099config GEOS 3100 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3101 select GPIOLIB 3102 select GEODE_COMMON 3103 depends on DMI 3104 help 3105 This option enables system support for the Traverse Technologies GEOS. 3106 3107config TS5500 3108 bool "Technologic Systems TS-5500 platform support" 3109 depends on MELAN 3110 select CHECK_SIGNATURE 3111 select NEW_LEDS 3112 select LEDS_CLASS 3113 help 3114 This option enables system support for the Technologic Systems TS-5500. 3115 3116endif # X86_32 3117 3118config AMD_NB 3119 def_bool y 3120 depends on CPU_SUP_AMD && PCI 3121 3122endmenu 3123 3124menu "Binary Emulations" 3125 3126config IA32_EMULATION 3127 bool "IA32 Emulation" 3128 depends on X86_64 3129 select ARCH_WANT_OLD_COMPAT_IPC 3130 select BINFMT_ELF 3131 select COMPAT_OLD_SIGACTION 3132 help 3133 Include code to run legacy 32-bit programs under a 3134 64-bit kernel. You should likely turn this on, unless you're 3135 100% sure that you don't have any 32-bit programs left. 3136 3137config IA32_EMULATION_DEFAULT_DISABLED 3138 bool "IA32 emulation disabled by default" 3139 default n 3140 depends on IA32_EMULATION 3141 help 3142 Make IA32 emulation disabled by default. This prevents loading 32-bit 3143 processes and access to 32-bit syscalls. If unsure, leave it to its 3144 default value. 3145 3146config X86_X32_ABI 3147 bool "x32 ABI for 64-bit mode" 3148 depends on X86_64 3149 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3150 # compressed debug sections to x86_x32 properly: 3151 # https://github.com/ClangBuiltLinux/linux/issues/514 3152 # https://github.com/ClangBuiltLinux/linux/issues/1141 3153 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3154 help 3155 Include code to run binaries for the x32 native 32-bit ABI 3156 for 64-bit processors. An x32 process gets access to the 3157 full 64-bit register file and wide data path while leaving 3158 pointers at 32 bits for smaller memory footprint. 3159 3160config COMPAT_32 3161 def_bool y 3162 depends on IA32_EMULATION || X86_32 3163 select HAVE_UID16 3164 select OLD_SIGSUSPEND3 3165 3166config COMPAT 3167 def_bool y 3168 depends on IA32_EMULATION || X86_X32_ABI 3169 3170config COMPAT_FOR_U64_ALIGNMENT 3171 def_bool y 3172 depends on COMPAT 3173 3174endmenu 3175 3176config HAVE_ATOMIC_IOMAP 3177 def_bool y 3178 depends on X86_32 3179 3180source "arch/x86/kvm/Kconfig" 3181 3182source "arch/x86/Kconfig.assembler" 3183