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_MSEAL_SYSTEM_MAPPINGS 30 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 31 select ARCH_SUPPORTS_PER_VMA_LOCK 32 select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE 33 select HAVE_ARCH_SOFT_DIRTY 34 select MODULES_USE_ELF_RELA 35 select NEED_DMA_MAP_STATE 36 select SWIOTLB 37 select ARCH_HAS_ELFCORE_COMPAT 38 select ZONE_DMA32 39 select EXECMEM if DYNAMIC_FTRACE 40 select ACPI_MRRM if ACPI 41 42config FORCE_DYNAMIC_FTRACE 43 def_bool y 44 depends on X86_32 45 depends on FUNCTION_TRACER 46 select DYNAMIC_FTRACE 47 help 48 We keep the static function tracing (!DYNAMIC_FTRACE) around 49 in order to test the non static function tracing in the 50 generic code, as other architectures still use it. But we 51 only need to keep it around for x86_64. No need to keep it 52 for x86_32. For x86_32, force DYNAMIC_FTRACE. 53# 54# Arch settings 55# 56# ( Note that options that are marked 'if X86_64' could in principle be 57# ported to 32-bit as well. ) 58# 59config X86 60 def_bool y 61 # 62 # Note: keep this list sorted alphabetically 63 # 64 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 65 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 66 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 67 select ARCH_32BIT_OFF_T if X86_32 68 select ARCH_CLOCKSOURCE_INIT 69 select ARCH_CONFIGURES_CPU_MITIGATIONS 70 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 71 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 72 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 73 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 74 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 75 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 76 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 77 select ARCH_HAS_CPU_ATTACK_VECTORS if CPU_MITIGATIONS 78 select ARCH_HAS_CACHE_LINE_SIZE 79 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 80 select ARCH_HAS_CPU_FINALIZE_INIT 81 select ARCH_HAS_CPU_PASID if IOMMU_SVA 82 select ARCH_HAS_CURRENT_STACK_POINTER 83 select ARCH_HAS_DEBUG_VIRTUAL 84 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 85 select ARCH_HAS_DEVMEM_IS_ALLOWED 86 select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN 87 select ARCH_HAS_EARLY_DEBUG if KGDB 88 select ARCH_HAS_ELF_RANDOMIZE 89 select ARCH_HAS_EXECMEM_ROX if X86_64 && STRICT_MODULE_RWX 90 select ARCH_HAS_FAST_MULTIPLIER 91 select ARCH_HAS_FORTIFY_SOURCE 92 select ARCH_HAS_GCOV_PROFILE_ALL 93 select ARCH_HAS_KCOV if X86_64 94 select ARCH_HAS_KERNEL_FPU_SUPPORT 95 select ARCH_HAS_MEM_ENCRYPT 96 select ARCH_HAS_MEMBARRIER_SYNC_CORE 97 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 98 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 99 select ARCH_HAS_PMEM_API if X86_64 100 select ARCH_HAS_PREEMPT_LAZY 101 select ARCH_HAS_PTDUMP 102 select ARCH_HAS_PTE_SPECIAL 103 select ARCH_HAS_HW_PTE_YOUNG 104 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 105 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 106 select ARCH_HAS_COPY_MC if X86_64 107 select ARCH_HAS_SET_MEMORY 108 select ARCH_HAS_SET_DIRECT_MAP 109 select ARCH_HAS_STRICT_KERNEL_RWX 110 select ARCH_HAS_STRICT_MODULE_RWX 111 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 112 select ARCH_HAS_SYSCALL_WRAPPER 113 select ARCH_HAS_UBSAN 114 select ARCH_HAS_DEBUG_WX 115 select ARCH_HAS_ZONE_DMA_SET if EXPERT 116 select ARCH_HAVE_NMI_SAFE_CMPXCHG 117 select ARCH_HAVE_EXTRA_ELF_NOTES 118 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 119 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 120 select ARCH_MIGHT_HAVE_PC_PARPORT 121 select ARCH_MIGHT_HAVE_PC_SERIO 122 select ARCH_STACKWALK 123 select ARCH_SUPPORTS_ACPI 124 select ARCH_SUPPORTS_ATOMIC_RMW 125 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 126 select ARCH_SUPPORTS_HUGETLBFS 127 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 128 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 129 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 130 select ARCH_SUPPORTS_CFI if X86_64 131 select ARCH_USES_CFI_TRAPS if X86_64 && CFI 132 select ARCH_SUPPORTS_LTO_CLANG 133 select ARCH_SUPPORTS_LTO_CLANG_THIN 134 select ARCH_SUPPORTS_RT 135 select ARCH_SUPPORTS_AUTOFDO_CLANG 136 select ARCH_SUPPORTS_PROPELLER_CLANG if X86_64 137 select ARCH_USE_BUILTIN_BSWAP 138 select ARCH_USE_CMPXCHG_LOCKREF if X86_CX8 139 select ARCH_USE_MEMTEST 140 select ARCH_USE_QUEUED_RWLOCKS 141 select ARCH_USE_QUEUED_SPINLOCKS 142 select ARCH_USE_SYM_ANNOTATIONS 143 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 144 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 145 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 146 select ARCH_WANTS_NO_INSTR 147 select ARCH_WANT_GENERAL_HUGETLB 148 select ARCH_WANT_HUGE_PMD_SHARE if X86_64 149 select ARCH_WANT_LD_ORPHAN_WARN 150 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 151 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 152 select ARCH_WANT_HUGETLB_VMEMMAP_PREINIT if X86_64 153 select ARCH_WANTS_THP_SWAP if X86_64 154 select ARCH_HAS_PARANOID_L1D_FLUSH 155 select ARCH_WANT_IRQS_OFF_ACTIVATE_MM 156 select BUILDTIME_TABLE_SORT 157 select CLKEVT_I8253 158 select CLOCKSOURCE_WATCHDOG 159 # Word-size accesses may read uninitialized data past the trailing \0 160 # in strings and cause false KMSAN reports. 161 select DCACHE_WORD_ACCESS if !KMSAN 162 select DYNAMIC_SIGFRAME 163 select EDAC_ATOMIC_SCRUB 164 select EDAC_SUPPORT 165 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 166 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 167 select GENERIC_CLOCKEVENTS_MIN_ADJUST 168 select GENERIC_CMOS_UPDATE 169 select GENERIC_CPU_AUTOPROBE 170 select GENERIC_CPU_DEVICES 171 select GENERIC_CPU_VULNERABILITIES 172 select GENERIC_EARLY_IOREMAP 173 select GENERIC_ENTRY 174 select GENERIC_IOMAP 175 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 176 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 177 select GENERIC_IRQ_MIGRATION if SMP 178 select GENERIC_IRQ_PROBE 179 select GENERIC_IRQ_RESERVATION_MODE 180 select GENERIC_IRQ_SHOW 181 select GENERIC_PENDING_IRQ if SMP 182 select GENERIC_SMP_IDLE_THREAD 183 select GENERIC_TIME_VSYSCALL 184 select GENERIC_GETTIMEOFDAY 185 select GENERIC_VDSO_DATA_STORE 186 select GENERIC_VDSO_TIME_NS 187 select GENERIC_VDSO_OVERFLOW_PROTECT 188 select GUP_GET_PXX_LOW_HIGH if X86_PAE 189 select HARDIRQS_SW_RESEND 190 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 191 select HAS_IOPORT 192 select HAVE_ACPI_APEI if ACPI 193 select HAVE_ACPI_APEI_NMI if ACPI 194 select HAVE_ALIGNED_STRUCT_PAGE 195 select HAVE_ARCH_AUDITSYSCALL 196 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 197 select HAVE_ARCH_HUGE_VMALLOC if X86_64 198 select HAVE_ARCH_JUMP_LABEL 199 select HAVE_ARCH_JUMP_LABEL_RELATIVE 200 select HAVE_ARCH_KASAN if X86_64 201 select HAVE_ARCH_KASAN_VMALLOC if X86_64 202 select HAVE_ARCH_KFENCE 203 select HAVE_ARCH_KMSAN if X86_64 204 select HAVE_ARCH_KGDB 205 select HAVE_ARCH_KSTACK_ERASE 206 select HAVE_ARCH_MMAP_RND_BITS if MMU 207 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 208 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 209 select HAVE_ARCH_PREL32_RELOCATIONS 210 select HAVE_ARCH_SECCOMP_FILTER 211 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 212 select HAVE_ARCH_TRACEHOOK 213 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 214 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 215 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 216 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 217 select HAVE_ARCH_VMAP_STACK if X86_64 218 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 219 select HAVE_ARCH_WITHIN_STACK_FRAMES 220 select HAVE_ASM_MODVERSIONS 221 select HAVE_CMPXCHG_DOUBLE 222 select HAVE_CMPXCHG_LOCAL 223 select HAVE_CONTEXT_TRACKING_USER if X86_64 224 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 225 select HAVE_C_RECORDMCOUNT 226 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 227 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 228 select HAVE_BUILDTIME_MCOUNT_SORT 229 select HAVE_DEBUG_KMEMLEAK 230 select HAVE_DMA_CONTIGUOUS 231 select HAVE_DYNAMIC_FTRACE 232 select HAVE_DYNAMIC_FTRACE_WITH_REGS 233 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 234 select HAVE_FTRACE_REGS_HAVING_PT_REGS if X86_64 235 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 236 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 237 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 238 select HAVE_EBPF_JIT 239 select HAVE_EFFICIENT_UNALIGNED_ACCESS 240 select HAVE_EISA if X86_32 241 select HAVE_EXIT_THREAD 242 select HAVE_GUP_FAST 243 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 244 select HAVE_FTRACE_GRAPH_FUNC if HAVE_FUNCTION_GRAPH_TRACER 245 select HAVE_FUNCTION_GRAPH_FREGS if HAVE_FUNCTION_GRAPH_TRACER 246 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 247 select HAVE_FUNCTION_TRACER 248 select HAVE_GCC_PLUGINS 249 select HAVE_HW_BREAKPOINT 250 select HAVE_IOREMAP_PROT 251 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 252 select HAVE_IRQ_TIME_ACCOUNTING 253 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 254 select HAVE_KERNEL_BZIP2 255 select HAVE_KERNEL_GZIP 256 select HAVE_KERNEL_LZ4 257 select HAVE_KERNEL_LZMA 258 select HAVE_KERNEL_LZO 259 select HAVE_KERNEL_XZ 260 select HAVE_KERNEL_ZSTD 261 select HAVE_KPROBES 262 select HAVE_KPROBES_ON_FTRACE 263 select HAVE_FUNCTION_ERROR_INJECTION 264 select HAVE_KRETPROBES 265 select HAVE_RETHOOK 266 select HAVE_LIVEPATCH if X86_64 267 select HAVE_MIXED_BREAKPOINTS_REGS 268 select HAVE_MOD_ARCH_SPECIFIC 269 select HAVE_MOVE_PMD 270 select HAVE_MOVE_PUD 271 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 272 select HAVE_NMI 273 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 274 select HAVE_OBJTOOL if X86_64 275 select HAVE_OPTPROBES 276 select HAVE_PAGE_SIZE_4KB 277 select HAVE_PCSPKR_PLATFORM 278 select HAVE_PERF_EVENTS 279 select HAVE_PERF_EVENTS_NMI 280 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 281 select HAVE_PCI 282 select HAVE_PERF_REGS 283 select HAVE_PERF_USER_STACK_DUMP 284 select MMU_GATHER_RCU_TABLE_FREE 285 select MMU_GATHER_MERGE_VMAS 286 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 287 select HAVE_REGS_AND_STACK_ACCESS_API 288 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 289 select HAVE_FUNCTION_ARG_ACCESS_API 290 select HAVE_SETUP_PER_CPU_AREA 291 select HAVE_SOFTIRQ_ON_OWN_STACK 292 select HAVE_STACKPROTECTOR 293 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 294 select HAVE_STATIC_CALL 295 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 296 select HAVE_PREEMPT_DYNAMIC_CALL 297 select HAVE_RSEQ 298 select HAVE_RUST if X86_64 299 select HAVE_SYSCALL_TRACEPOINTS 300 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 301 select HAVE_UNSTABLE_SCHED_CLOCK 302 select HAVE_USER_RETURN_NOTIFIER 303 select HAVE_GENERIC_VDSO 304 select VDSO_GETRANDOM if X86_64 305 select HOTPLUG_PARALLEL if SMP && X86_64 306 select HOTPLUG_SMT if SMP 307 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 308 select IRQ_FORCED_THREADING 309 select LOCK_MM_AND_FIND_VMA 310 select NEED_PER_CPU_EMBED_FIRST_CHUNK 311 select NEED_PER_CPU_PAGE_FIRST_CHUNK 312 select NEED_SG_DMA_LENGTH 313 select NUMA_MEMBLKS if NUMA 314 select PCI_DOMAINS if PCI 315 select PCI_LOCKLESS_CONFIG if PCI 316 select PERF_EVENTS 317 select RTC_LIB 318 select RTC_MC146818_LIB 319 select SPARSE_IRQ 320 select SYSCTL_EXCEPTION_TRACE 321 select THREAD_INFO_IN_TASK 322 select TRACE_IRQFLAGS_SUPPORT 323 select TRACE_IRQFLAGS_NMI_SUPPORT 324 select USER_STACKTRACE_SUPPORT 325 select HAVE_ARCH_KCSAN if X86_64 326 select PROC_PID_ARCH_STATUS if PROC_FS 327 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 328 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 329 select FUNCTION_ALIGNMENT_4B 330 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 331 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 332 select ARCH_SUPPORTS_PT_RECLAIM if X86_64 333 select ARCH_SUPPORTS_SCHED_SMT if SMP 334 select SCHED_SMT if SMP 335 select ARCH_SUPPORTS_SCHED_CLUSTER if SMP 336 select ARCH_SUPPORTS_SCHED_MC if SMP 337 338config INSTRUCTION_DECODER 339 def_bool y 340 depends on KPROBES || PERF_EVENTS || UPROBES 341 342config OUTPUT_FORMAT 343 string 344 default "elf32-i386" if X86_32 345 default "elf64-x86-64" if X86_64 346 347config LOCKDEP_SUPPORT 348 def_bool y 349 350config STACKTRACE_SUPPORT 351 def_bool y 352 353config MMU 354 def_bool y 355 356config ARCH_MMAP_RND_BITS_MIN 357 default 28 if 64BIT 358 default 8 359 360config ARCH_MMAP_RND_BITS_MAX 361 default 32 if 64BIT 362 default 16 363 364config ARCH_MMAP_RND_COMPAT_BITS_MIN 365 default 8 366 367config ARCH_MMAP_RND_COMPAT_BITS_MAX 368 default 16 369 370config SBUS 371 bool 372 373config GENERIC_ISA_DMA 374 def_bool y 375 depends on ISA_DMA_API 376 377config GENERIC_CSUM 378 bool 379 default y if KMSAN || KASAN 380 381config GENERIC_BUG 382 def_bool y 383 depends on BUG 384 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 385 386config GENERIC_BUG_RELATIVE_POINTERS 387 bool 388 389config ARCH_MAY_HAVE_PC_FDC 390 def_bool y 391 depends on ISA_DMA_API 392 393config GENERIC_CALIBRATE_DELAY 394 def_bool y 395 396config ARCH_HAS_CPU_RELAX 397 def_bool y 398 399config ARCH_HIBERNATION_POSSIBLE 400 def_bool y 401 402config ARCH_SUSPEND_POSSIBLE 403 def_bool y 404 405config AUDIT_ARCH 406 def_bool y if X86_64 407 408config KASAN_SHADOW_OFFSET 409 hex 410 depends on KASAN 411 default 0xdffffc0000000000 412 413config HAVE_INTEL_TXT 414 def_bool y 415 depends on INTEL_IOMMU && ACPI 416 417config X86_64_SMP 418 def_bool y 419 depends on X86_64 && SMP 420 421config ARCH_SUPPORTS_UPROBES 422 def_bool y 423 424config FIX_EARLYCON_MEM 425 def_bool y 426 427config DYNAMIC_PHYSICAL_MASK 428 bool 429 430config PGTABLE_LEVELS 431 int 432 default 5 if X86_64 433 default 3 if X86_PAE 434 default 2 435 436menu "Processor type and features" 437 438config SMP 439 bool "Symmetric multi-processing support" 440 help 441 This enables support for systems with more than one CPU. If you have 442 a system with only one CPU, say N. If you have a system with more 443 than one CPU, say Y. 444 445 If you say N here, the kernel will run on uni- and multiprocessor 446 machines, but will use only one CPU of a multiprocessor machine. If 447 you say Y here, the kernel will run on many, but not all, 448 uniprocessor machines. On a uniprocessor machine, the kernel 449 will run faster if you say N here. 450 451 Note that if you say Y here and choose architecture "586" or 452 "Pentium" under "Processor family", the kernel will not work on 486 453 architectures. Similarly, multiprocessor kernels for the "PPro" 454 architecture may not work on all Pentium based boards. 455 456 People using multiprocessor machines who say Y here should also say 457 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 458 Management" code will be disabled if you say Y here. 459 460 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 461 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 462 <http://www.tldp.org/docs.html#howto>. 463 464 If you don't know what to do here, say N. 465 466config X86_X2APIC 467 bool "x2APIC interrupt controller architecture support" 468 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 469 default y 470 help 471 x2APIC is an interrupt controller architecture, a component of which 472 (the local APIC) is present in the CPU. It allows faster access to 473 the local APIC and supports a larger number of CPUs in the system 474 than the predecessors. 475 476 x2APIC was introduced in Intel CPUs around 2008 and in AMD EPYC CPUs 477 in 2019, but it can be disabled by the BIOS. It is also frequently 478 emulated in virtual machines, even when the host CPU does not support 479 it. Support in the CPU can be checked by executing 480 grep x2apic /proc/cpuinfo 481 482 If this configuration option is disabled, the kernel will boot with 483 very reduced functionality and performance on some platforms that 484 have x2APIC enabled. On the other hand, on hardware that does not 485 support x2APIC, a kernel with this option enabled will just fallback 486 to older APIC implementations. 487 488 If in doubt, say Y. 489 490config X86_POSTED_MSI 491 bool "Enable MSI and MSI-x delivery by posted interrupts" 492 depends on X86_64 && IRQ_REMAP 493 help 494 This enables MSIs that are under interrupt remapping to be delivered as 495 posted interrupts to the host kernel. Interrupt throughput can 496 potentially be improved by coalescing CPU notifications during high 497 frequency bursts. 498 499 If you don't know what to do here, say N. 500 501config X86_MPPARSE 502 bool "Enable MPS table" if ACPI 503 default y 504 depends on X86_LOCAL_APIC 505 help 506 For old smp systems that do not have proper acpi support. Newer systems 507 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 508 509config X86_CPU_RESCTRL 510 bool "x86 CPU resource control support" 511 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 512 depends on MISC_FILESYSTEMS 513 select ARCH_HAS_CPU_RESCTRL 514 select RESCTRL_FS 515 select RESCTRL_FS_PSEUDO_LOCK 516 help 517 Enable x86 CPU resource control support. 518 519 Provide support for the allocation and monitoring of system resources 520 usage by the CPU. 521 522 Intel calls this Intel Resource Director Technology 523 (Intel(R) RDT). More information about RDT can be found in the 524 Intel x86 Architecture Software Developer Manual. 525 526 AMD calls this AMD Platform Quality of Service (AMD QoS). 527 More information about AMD QoS can be found in the AMD64 Technology 528 Platform Quality of Service Extensions manual. 529 530 Say N if unsure. 531 532config X86_FRED 533 bool "Flexible Return and Event Delivery" 534 depends on X86_64 535 help 536 When enabled, try to use Flexible Return and Event Delivery 537 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 538 ring transitions and exception/interrupt handling if the 539 system supports it. 540 541config X86_EXTENDED_PLATFORM 542 bool "Support for extended (non-PC) x86 platforms" 543 default y 544 help 545 If you disable this option then the kernel will only support 546 standard PC platforms. (which covers the vast majority of 547 systems out there.) 548 549 If you enable this option then you'll be able to select support 550 for the following non-PC x86 platforms, depending on the value of 551 CONFIG_64BIT. 552 553 32-bit platforms (CONFIG_64BIT=n): 554 Goldfish (mostly Android emulator) 555 Intel CE media processor (CE4100) SoC 556 Intel Quark 557 RDC R-321x SoC 558 559 64-bit platforms (CONFIG_64BIT=y): 560 Numascale NumaChip 561 ScaleMP vSMP 562 SGI Ultraviolet 563 Merrifield/Moorefield MID devices 564 Goldfish (mostly Android emulator) 565 566 If you have one of these systems, or if you want to build a 567 generic distribution kernel, say Y here - otherwise say N. 568 569# This is an alphabetically sorted list of 64 bit extended platforms 570# Please maintain the alphabetic order if and when there are additions 571config X86_NUMACHIP 572 bool "Numascale NumaChip" 573 depends on X86_64 574 depends on X86_EXTENDED_PLATFORM 575 depends on NUMA 576 depends on SMP 577 depends on X86_X2APIC 578 depends on PCI_MMCONFIG 579 help 580 Adds support for Numascale NumaChip large-SMP systems. Needed to 581 enable more than ~168 cores. 582 If you don't have one of these, you should say N here. 583 584config X86_VSMP 585 bool "ScaleMP vSMP" 586 select HYPERVISOR_GUEST 587 select PARAVIRT 588 depends on X86_64 && PCI 589 depends on X86_EXTENDED_PLATFORM 590 depends on SMP 591 help 592 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 593 supposed to run on these EM64T-based machines. Only choose this option 594 if you have one of these machines. 595 596config X86_UV 597 bool "SGI Ultraviolet" 598 depends on X86_64 599 depends on X86_EXTENDED_PLATFORM 600 depends on NUMA 601 depends on EFI 602 depends on KEXEC_CORE 603 depends on X86_X2APIC 604 depends on PCI 605 help 606 This option is needed in order to support SGI Ultraviolet systems. 607 If you don't have one of these, you should say N here. 608 609config X86_INTEL_MID 610 bool "Intel Z34xx/Z35xx MID platform support" 611 depends on X86_EXTENDED_PLATFORM 612 depends on X86_PLATFORM_DEVICES 613 depends on PCI 614 depends on X86_64 || (EXPERT && PCI_GOANY) 615 depends on X86_IO_APIC 616 select I2C 617 select DW_APB_TIMER 618 select INTEL_SCU_PCI 619 help 620 Select to build a kernel capable of supporting 64-bit Intel MID 621 (Mobile Internet Device) platform systems which do not have 622 the PCI legacy interfaces. 623 624 The only supported devices are the 22nm Merrified (Z34xx) 625 and Moorefield (Z35xx) SoC used in the Intel Edison board and 626 a small number of Android devices such as the Asus Zenfone 2, 627 Asus FonePad 8 and Dell Venue 7. 628 629 If you are building for a PC class system or non-MID tablet 630 SoCs like Bay Trail (Z36xx/Z37xx), say N here. 631 632 Intel MID platforms are based on an Intel processor and chipset which 633 consume less power than most of the x86 derivatives. 634 635config X86_GOLDFISH 636 bool "Goldfish (Virtual Platform)" 637 depends on X86_EXTENDED_PLATFORM 638 help 639 Enable support for the Goldfish virtual platform used primarily 640 for Android development. Unless you are building for the Android 641 Goldfish emulator say N here. 642 643# Following is an alphabetically sorted list of 32 bit extended platforms 644# Please maintain the alphabetic order if and when there are additions 645 646config X86_INTEL_CE 647 bool "CE4100 TV platform" 648 depends on PCI 649 depends on PCI_GODIRECT 650 depends on X86_IO_APIC 651 depends on X86_32 652 depends on X86_EXTENDED_PLATFORM 653 select X86_REBOOTFIXUPS 654 select OF 655 select OF_EARLY_FLATTREE 656 help 657 Select for the Intel CE media processor (CE4100) SOC. 658 This option compiles in support for the CE4100 SOC for settop 659 boxes and media devices. 660 661config X86_INTEL_QUARK 662 bool "Intel Quark platform support" 663 depends on X86_32 664 depends on X86_EXTENDED_PLATFORM 665 depends on X86_PLATFORM_DEVICES 666 depends on X86_TSC 667 depends on PCI 668 depends on PCI_GOANY 669 depends on X86_IO_APIC 670 select IOSF_MBI 671 select INTEL_IMR 672 select COMMON_CLK 673 help 674 Select to include support for Quark X1000 SoC. 675 Say Y here if you have a Quark based system such as the Arduino 676 compatible Intel Galileo. 677 678config X86_RDC321X 679 bool "RDC R-321x SoC" 680 depends on X86_32 681 depends on X86_EXTENDED_PLATFORM 682 select M486 683 select X86_REBOOTFIXUPS 684 help 685 This option is needed for RDC R-321x system-on-chip, also known 686 as R-8610-(G). 687 If you don't have one of these chips, you should say N here. 688 689config X86_INTEL_LPSS 690 bool "Intel Low Power Subsystem Support" 691 depends on X86 && ACPI && PCI 692 select COMMON_CLK 693 select PINCTRL 694 select IOSF_MBI 695 help 696 Select to build support for Intel Low Power Subsystem such as 697 found on Intel Lynxpoint PCH. Selecting this option enables 698 things like clock tree (common clock framework) and pincontrol 699 which are needed by the LPSS peripheral drivers. 700 701config X86_AMD_PLATFORM_DEVICE 702 bool "AMD ACPI2Platform devices support" 703 depends on ACPI 704 select COMMON_CLK 705 select PINCTRL 706 help 707 Select to interpret AMD specific ACPI device to platform device 708 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 709 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 710 implemented under PINCTRL subsystem. 711 712config IOSF_MBI 713 tristate "Intel SoC IOSF Sideband support for SoC platforms" 714 depends on PCI 715 help 716 This option enables sideband register access support for Intel SoC 717 platforms. On these platforms the IOSF sideband is used in lieu of 718 MSR's for some register accesses, mostly but not limited to thermal 719 and power. Drivers may query the availability of this device to 720 determine if they need the sideband in order to work on these 721 platforms. The sideband is available on the following SoC products. 722 This list is not meant to be exclusive. 723 - BayTrail 724 - Braswell 725 - Quark 726 727 You should say Y if you are running a kernel on one of these SoC's. 728 729config IOSF_MBI_DEBUG 730 bool "Enable IOSF sideband access through debugfs" 731 depends on IOSF_MBI && DEBUG_FS 732 help 733 Select this option to expose the IOSF sideband access registers (MCR, 734 MDR, MCRX) through debugfs to write and read register information from 735 different units on the SoC. This is most useful for obtaining device 736 state information for debug and analysis. As this is a general access 737 mechanism, users of this option would have specific knowledge of the 738 device they want to access. 739 740 If you don't require the option or are in doubt, say N. 741 742config X86_SUPPORTS_MEMORY_FAILURE 743 def_bool y 744 # MCE code calls memory_failure(): 745 depends on X86_MCE 746 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 747 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 748 depends on X86_64 || !SPARSEMEM 749 select ARCH_SUPPORTS_MEMORY_FAILURE 750 751config X86_32_IRIS 752 tristate "Eurobraille/Iris poweroff module" 753 depends on X86_32 754 help 755 The Iris machines from EuroBraille do not have APM or ACPI support 756 to shut themselves down properly. A special I/O sequence is 757 needed to do so, which is what this module does at 758 kernel shutdown. 759 760 This is only for Iris machines from EuroBraille. 761 762 If unused, say N. 763 764config SCHED_OMIT_FRAME_POINTER 765 def_bool y 766 prompt "Single-depth WCHAN output" 767 depends on X86 768 help 769 Calculate simpler /proc/<PID>/wchan values. If this option 770 is disabled then wchan values will recurse back to the 771 caller function. This provides more accurate wchan values, 772 at the expense of slightly more scheduling overhead. 773 774 If in doubt, say "Y". 775 776menuconfig HYPERVISOR_GUEST 777 bool "Linux guest support" 778 help 779 Say Y here to enable options for running Linux under various hyper- 780 visors. This option enables basic hypervisor detection and platform 781 setup. 782 783 If you say N, all options in this submenu will be skipped and 784 disabled, and Linux guest support won't be built in. 785 786if HYPERVISOR_GUEST 787 788config PARAVIRT 789 bool "Enable paravirtualization code" 790 depends on HAVE_STATIC_CALL 791 help 792 This changes the kernel so it can modify itself when it is run 793 under a hypervisor, potentially improving performance significantly 794 over full virtualization. However, when run without a hypervisor 795 the kernel is theoretically slower and slightly larger. 796 797config PARAVIRT_XXL 798 bool 799 depends on X86_64 800 801config PARAVIRT_DEBUG 802 bool "paravirt-ops debugging" 803 depends on PARAVIRT && DEBUG_KERNEL 804 help 805 Enable to debug paravirt_ops internals. Specifically, BUG if 806 a paravirt_op is missing when it is called. 807 808config PARAVIRT_SPINLOCKS 809 bool "Paravirtualization layer for spinlocks" 810 depends on PARAVIRT && SMP 811 help 812 Paravirtualized spinlocks allow a pvops backend to replace the 813 spinlock implementation with something virtualization-friendly 814 (for example, block the virtual CPU rather than spinning). 815 816 It has a minimal impact on native kernels and gives a nice performance 817 benefit on paravirtualized KVM / Xen kernels. 818 819 If you are unsure how to answer this question, answer Y. 820 821config X86_HV_CALLBACK_VECTOR 822 def_bool n 823 824source "arch/x86/xen/Kconfig" 825 826config KVM_GUEST 827 bool "KVM Guest support (including kvmclock)" 828 depends on PARAVIRT 829 select PARAVIRT_CLOCK 830 select ARCH_CPUIDLE_HALTPOLL 831 select X86_HV_CALLBACK_VECTOR 832 default y 833 help 834 This option enables various optimizations for running under the KVM 835 hypervisor. It includes a paravirtualized clock, so that instead 836 of relying on a PIT (or probably other) emulation by the 837 underlying device model, the host provides the guest with 838 timing infrastructure such as time of day, and system time 839 840config ARCH_CPUIDLE_HALTPOLL 841 def_bool n 842 prompt "Disable host haltpoll when loading haltpoll driver" 843 help 844 If virtualized under KVM, disable host haltpoll. 845 846config PVH 847 bool "Support for running PVH guests" 848 help 849 This option enables the PVH entry point for guest virtual machines 850 as specified in the x86/HVM direct boot ABI. 851 852config PARAVIRT_TIME_ACCOUNTING 853 bool "Paravirtual steal time accounting" 854 depends on PARAVIRT 855 help 856 Select this option to enable fine granularity task steal time 857 accounting. Time spent executing other tasks in parallel with 858 the current vCPU is discounted from the vCPU power. To account for 859 that, there can be a small performance impact. 860 861 If in doubt, say N here. 862 863config PARAVIRT_CLOCK 864 bool 865 866config JAILHOUSE_GUEST 867 bool "Jailhouse non-root cell support" 868 depends on X86_64 && PCI 869 select X86_PM_TIMER 870 help 871 This option allows to run Linux as guest in a Jailhouse non-root 872 cell. You can leave this option disabled if you only want to start 873 Jailhouse and run Linux afterwards in the root cell. 874 875config ACRN_GUEST 876 bool "ACRN Guest support" 877 depends on X86_64 878 select X86_HV_CALLBACK_VECTOR 879 help 880 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 881 a flexible, lightweight reference open-source hypervisor, built with 882 real-time and safety-criticality in mind. It is built for embedded 883 IOT with small footprint and real-time features. More details can be 884 found in https://projectacrn.org/. 885 886config INTEL_TDX_GUEST 887 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 888 depends on X86_64 && CPU_SUP_INTEL 889 depends on X86_X2APIC 890 depends on EFI_STUB 891 depends on PARAVIRT 892 select ARCH_HAS_CC_PLATFORM 893 select X86_MEM_ENCRYPT 894 select X86_MCE 895 select UNACCEPTED_MEMORY 896 help 897 Support running as a guest under Intel TDX. Without this support, 898 the guest kernel can not boot or run under TDX. 899 TDX includes memory encryption and integrity capabilities 900 which protect the confidentiality and integrity of guest 901 memory contents and CPU state. TDX guests are protected from 902 some attacks from the VMM. 903 904endif # HYPERVISOR_GUEST 905 906source "arch/x86/Kconfig.cpu" 907 908config HPET_TIMER 909 def_bool X86_64 910 prompt "HPET Timer Support" if X86_32 911 help 912 Use the IA-PC HPET (High Precision Event Timer) to manage 913 time in preference to the PIT and RTC, if a HPET is 914 present. 915 HPET is the next generation timer replacing legacy 8254s. 916 The HPET provides a stable time base on SMP 917 systems, unlike the TSC, but it is more expensive to access, 918 as it is off-chip. The interface used is documented 919 in the HPET spec, revision 1. 920 921 You can safely choose Y here. However, HPET will only be 922 activated if the platform and the BIOS support this feature. 923 Otherwise the 8254 will be used for timing services. 924 925 Choose N to continue using the legacy 8254 timer. 926 927config HPET_EMULATE_RTC 928 def_bool y 929 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 930 931# Mark as expert because too many people got it wrong. 932# The code disables itself when not needed. 933config DMI 934 default y 935 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 936 bool "Enable DMI scanning" if EXPERT 937 help 938 Enabled scanning of DMI to identify machine quirks. Say Y 939 here unless you have verified that your setup is not 940 affected by entries in the DMI blacklist. Required by PNP 941 BIOS code. 942 943config GART_IOMMU 944 bool "Old AMD GART IOMMU support" 945 select IOMMU_HELPER 946 select SWIOTLB 947 depends on X86_64 && PCI && AMD_NB 948 help 949 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 950 GART based hardware IOMMUs. 951 952 The GART supports full DMA access for devices with 32-bit access 953 limitations, on systems with more than 3 GB. This is usually needed 954 for USB, sound, many IDE/SATA chipsets and some other devices. 955 956 Newer systems typically have a modern AMD IOMMU, supported via 957 the CONFIG_AMD_IOMMU=y config option. 958 959 In normal configurations this driver is only active when needed: 960 there's more than 3 GB of memory and the system contains a 961 32-bit limited device. 962 963 If unsure, say Y. 964 965config BOOT_VESA_SUPPORT 966 bool 967 help 968 If true, at least one selected framebuffer driver can take advantage 969 of VESA video modes set at an early boot stage via the vga= parameter. 970 971config MAXSMP 972 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 973 depends on X86_64 && SMP && DEBUG_KERNEL 974 select CPUMASK_OFFSTACK 975 help 976 Enable maximum number of CPUS and NUMA Nodes for this architecture. 977 If unsure, say N. 978 979# 980# The maximum number of CPUs supported: 981# 982# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 983# and which can be configured interactively in the 984# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 985# 986# The ranges are different on 32-bit and 64-bit kernels, depending on 987# hardware capabilities and scalability features of the kernel. 988# 989# ( If MAXSMP is enabled we just use the highest possible value and disable 990# interactive configuration. ) 991# 992 993config NR_CPUS_RANGE_BEGIN 994 int 995 default NR_CPUS_RANGE_END if MAXSMP 996 default 1 if !SMP 997 default 2 998 999config NR_CPUS_RANGE_END 1000 int 1001 depends on X86_32 1002 default 8 if SMP 1003 default 1 if !SMP 1004 1005config NR_CPUS_RANGE_END 1006 int 1007 depends on X86_64 1008 default 8192 if SMP && CPUMASK_OFFSTACK 1009 default 512 if SMP && !CPUMASK_OFFSTACK 1010 default 1 if !SMP 1011 1012config NR_CPUS_DEFAULT 1013 int 1014 depends on X86_32 1015 default 8 if SMP 1016 default 1 if !SMP 1017 1018config NR_CPUS_DEFAULT 1019 int 1020 depends on X86_64 1021 default 8192 if MAXSMP 1022 default 64 if SMP 1023 default 1 if !SMP 1024 1025config NR_CPUS 1026 int "Maximum number of CPUs" if SMP && !MAXSMP 1027 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1028 default NR_CPUS_DEFAULT 1029 help 1030 This allows you to specify the maximum number of CPUs which this 1031 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1032 supported value is 8192, otherwise the maximum value is 512. The 1033 minimum value which makes sense is 2. 1034 1035 This is purely to save memory: each supported CPU adds about 8KB 1036 to the kernel image. 1037 1038config SCHED_MC_PRIO 1039 bool "CPU core priorities scheduler support" 1040 depends on SCHED_MC 1041 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1042 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1043 select CPU_FREQ 1044 default y 1045 help 1046 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1047 core ordering determined at manufacturing time, which allows 1048 certain cores to reach higher turbo frequencies (when running 1049 single threaded workloads) than others. 1050 1051 Enabling this kernel feature teaches the scheduler about 1052 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1053 scheduler's CPU selection logic accordingly, so that higher 1054 overall system performance can be achieved. 1055 1056 This feature will have no effect on CPUs without this feature. 1057 1058 If unsure say Y here. 1059 1060config UP_LATE_INIT 1061 def_bool y 1062 depends on !SMP && X86_LOCAL_APIC 1063 1064config X86_UP_APIC 1065 bool "Local APIC support on uniprocessors" if !PCI_MSI 1066 default PCI_MSI 1067 depends on X86_32 && !SMP 1068 help 1069 A local APIC (Advanced Programmable Interrupt Controller) is an 1070 integrated interrupt controller in the CPU. If you have a single-CPU 1071 system which has a processor with a local APIC, you can say Y here to 1072 enable and use it. If you say Y here even though your machine doesn't 1073 have a local APIC, then the kernel will still run with no slowdown at 1074 all. The local APIC supports CPU-generated self-interrupts (timer, 1075 performance counters), and the NMI watchdog which detects hard 1076 lockups. 1077 1078config X86_UP_IOAPIC 1079 bool "IO-APIC support on uniprocessors" 1080 depends on X86_UP_APIC 1081 help 1082 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1083 SMP-capable replacement for PC-style interrupt controllers. Most 1084 SMP systems and many recent uniprocessor systems have one. 1085 1086 If you have a single-CPU system with an IO-APIC, you can say Y here 1087 to use it. If you say Y here even though your machine doesn't have 1088 an IO-APIC, then the kernel will still run with no slowdown at all. 1089 1090config X86_LOCAL_APIC 1091 def_bool y 1092 depends on X86_64 || SMP || X86_UP_APIC || PCI_MSI 1093 select IRQ_DOMAIN_HIERARCHY 1094 1095config ACPI_MADT_WAKEUP 1096 def_bool y 1097 depends on X86_64 1098 depends on ACPI 1099 depends on SMP 1100 depends on X86_LOCAL_APIC 1101 1102config X86_IO_APIC 1103 def_bool y 1104 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1105 1106config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1107 bool "Reroute for broken boot IRQs" 1108 depends on X86_IO_APIC 1109 help 1110 This option enables a workaround that fixes a source of 1111 spurious interrupts. This is recommended when threaded 1112 interrupt handling is used on systems where the generation of 1113 superfluous "boot interrupts" cannot be disabled. 1114 1115 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1116 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1117 kernel does during interrupt handling). On chipsets where this 1118 boot IRQ generation cannot be disabled, this workaround keeps 1119 the original IRQ line masked so that only the equivalent "boot 1120 IRQ" is delivered to the CPUs. The workaround also tells the 1121 kernel to set up the IRQ handler on the boot IRQ line. In this 1122 way only one interrupt is delivered to the kernel. Otherwise 1123 the spurious second interrupt may cause the kernel to bring 1124 down (vital) interrupt lines. 1125 1126 Only affects "broken" chipsets. Interrupt sharing may be 1127 increased on these systems. 1128 1129config X86_MCE 1130 bool "Machine Check / overheating reporting" 1131 select GENERIC_ALLOCATOR 1132 default y 1133 help 1134 Machine Check support allows the processor to notify the 1135 kernel if it detects a problem (e.g. overheating, data corruption). 1136 The action the kernel takes depends on the severity of the problem, 1137 ranging from warning messages to halting the machine. 1138 1139config X86_MCELOG_LEGACY 1140 bool "Support for deprecated /dev/mcelog character device" 1141 depends on X86_MCE 1142 help 1143 Enable support for /dev/mcelog which is needed by the old mcelog 1144 userspace logging daemon. Consider switching to the new generation 1145 rasdaemon solution. 1146 1147config X86_MCE_INTEL 1148 def_bool y 1149 prompt "Intel MCE features" 1150 depends on X86_MCE && X86_LOCAL_APIC 1151 help 1152 Additional support for intel specific MCE features such as 1153 the thermal monitor. 1154 1155config X86_MCE_AMD 1156 def_bool y 1157 prompt "AMD MCE features" 1158 depends on X86_MCE && X86_LOCAL_APIC 1159 help 1160 Additional support for AMD specific MCE features such as 1161 the DRAM Error Threshold. 1162 1163config X86_ANCIENT_MCE 1164 bool "Support for old Pentium 5 / WinChip machine checks" 1165 depends on X86_32 && X86_MCE 1166 help 1167 Include support for machine check handling on old Pentium 5 or WinChip 1168 systems. These typically need to be enabled explicitly on the command 1169 line. 1170 1171config X86_MCE_THRESHOLD 1172 depends on X86_MCE_AMD || X86_MCE_INTEL 1173 def_bool y 1174 1175config X86_MCE_INJECT 1176 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1177 tristate "Machine check injector support" 1178 help 1179 Provide support for injecting machine checks for testing purposes. 1180 If you don't know what a machine check is and you don't do kernel 1181 QA it is safe to say n. 1182 1183source "arch/x86/events/Kconfig" 1184 1185config X86_LEGACY_VM86 1186 bool "Legacy VM86 support" 1187 depends on X86_32 1188 help 1189 This option allows user programs to put the CPU into V8086 1190 mode, which is an 80286-era approximation of 16-bit real mode. 1191 1192 Some very old versions of X and/or vbetool require this option 1193 for user mode setting. Similarly, DOSEMU will use it if 1194 available to accelerate real mode DOS programs. However, any 1195 recent version of DOSEMU, X, or vbetool should be fully 1196 functional even without kernel VM86 support, as they will all 1197 fall back to software emulation. Nevertheless, if you are using 1198 a 16-bit DOS program where 16-bit performance matters, vm86 1199 mode might be faster than emulation and you might want to 1200 enable this option. 1201 1202 Note that any app that works on a 64-bit kernel is unlikely to 1203 need this option, as 64-bit kernels don't, and can't, support 1204 V8086 mode. This option is also unrelated to 16-bit protected 1205 mode and is not needed to run most 16-bit programs under Wine. 1206 1207 Enabling this option increases the complexity of the kernel 1208 and slows down exception handling a tiny bit. 1209 1210 If unsure, say N here. 1211 1212config VM86 1213 bool 1214 default X86_LEGACY_VM86 1215 1216config X86_16BIT 1217 bool "Enable support for 16-bit segments" if EXPERT 1218 default y 1219 depends on MODIFY_LDT_SYSCALL 1220 help 1221 This option is required by programs like Wine to run 16-bit 1222 protected mode legacy code on x86 processors. Disabling 1223 this option saves about 300 bytes on i386, or around 6K text 1224 plus 16K runtime memory on x86-64, 1225 1226config X86_ESPFIX32 1227 def_bool y 1228 depends on X86_16BIT && X86_32 1229 1230config X86_ESPFIX64 1231 def_bool y 1232 depends on X86_16BIT && X86_64 1233 1234config X86_VSYSCALL_EMULATION 1235 bool "Enable vsyscall emulation" if EXPERT 1236 default y 1237 depends on X86_64 1238 help 1239 This enables emulation of the legacy vsyscall page. Disabling 1240 it is roughly equivalent to booting with vsyscall=none, except 1241 that it will also disable the helpful warning if a program 1242 tries to use a vsyscall. With this option set to N, offending 1243 programs will just segfault, citing addresses of the form 1244 0xffffffffff600?00. 1245 1246 This option is required by many programs built before 2013, and 1247 care should be used even with newer programs if set to N. 1248 1249 Disabling this option saves about 7K of kernel size and 1250 possibly 4K of additional runtime pagetable memory. 1251 1252config X86_IOPL_IOPERM 1253 bool "IOPERM and IOPL Emulation" 1254 default y 1255 help 1256 This enables the ioperm() and iopl() syscalls which are necessary 1257 for legacy applications. 1258 1259 Legacy IOPL support is an overbroad mechanism which allows user 1260 space aside of accessing all 65536 I/O ports also to disable 1261 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1262 capabilities and permission from potentially active security 1263 modules. 1264 1265 The emulation restricts the functionality of the syscall to 1266 only allowing the full range I/O port access, but prevents the 1267 ability to disable interrupts from user space which would be 1268 granted if the hardware IOPL mechanism would be used. 1269 1270config TOSHIBA 1271 tristate "Toshiba Laptop support" 1272 depends on X86_32 1273 help 1274 This adds a driver to safely access the System Management Mode of 1275 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1276 not work on models with a Phoenix BIOS. The System Management Mode 1277 is used to set the BIOS and power saving options on Toshiba portables. 1278 1279 For information on utilities to make use of this driver see the 1280 Toshiba Linux utilities web site at: 1281 <http://www.buzzard.org.uk/toshiba/>. 1282 1283 Say Y if you intend to run this kernel on a Toshiba portable. 1284 Say N otherwise. 1285 1286config X86_REBOOTFIXUPS 1287 bool "Enable X86 board specific fixups for reboot" 1288 depends on X86_32 1289 help 1290 This enables chipset and/or board specific fixups to be done 1291 in order to get reboot to work correctly. This is only needed on 1292 some combinations of hardware and BIOS. The symptom, for which 1293 this config is intended, is when reboot ends with a stalled/hung 1294 system. 1295 1296 Currently, the only fixup is for the Geode machines using 1297 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1298 1299 Say Y if you want to enable the fixup. Currently, it's safe to 1300 enable this option even if you don't need it. 1301 Say N otherwise. 1302 1303config MICROCODE 1304 def_bool y 1305 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1306 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD 1307 1308config MICROCODE_INITRD32 1309 def_bool y 1310 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1311 1312config MICROCODE_LATE_LOADING 1313 bool "Late microcode loading (DANGEROUS)" 1314 default n 1315 depends on MICROCODE && SMP 1316 help 1317 Loading microcode late, when the system is up and executing instructions 1318 is a tricky business and should be avoided if possible. Just the sequence 1319 of synchronizing all cores and SMT threads is one fragile dance which does 1320 not guarantee that cores might not softlock after the loading. Therefore, 1321 use this at your own risk. Late loading taints the kernel unless the 1322 microcode header indicates that it is safe for late loading via the 1323 minimal revision check. This minimal revision check can be enforced on 1324 the kernel command line with "microcode.minrev=Y". 1325 1326config MICROCODE_LATE_FORCE_MINREV 1327 bool "Enforce late microcode loading minimal revision check" 1328 default n 1329 depends on MICROCODE_LATE_LOADING 1330 help 1331 To prevent that users load microcode late which modifies already 1332 in use features, newer microcode patches have a minimum revision field 1333 in the microcode header, which tells the kernel which minimum 1334 revision must be active in the CPU to safely load that new microcode 1335 late into the running system. If disabled the check will not 1336 be enforced but the kernel will be tainted when the minimal 1337 revision check fails. 1338 1339 This minimal revision check can also be controlled via the 1340 "microcode.minrev" parameter on the kernel command line. 1341 1342 If unsure say Y. 1343 1344config X86_MSR 1345 tristate "/dev/cpu/*/msr - Model-specific register support" 1346 help 1347 This device gives privileged processes access to the x86 1348 Model-Specific Registers (MSRs). It is a character device with 1349 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1350 MSR accesses are directed to a specific CPU on multi-processor 1351 systems. 1352 1353config X86_CPUID 1354 tristate "/dev/cpu/*/cpuid - CPU information support" 1355 help 1356 This device gives processes access to the x86 CPUID instruction to 1357 be executed on a specific processor. It is a character device 1358 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1359 /dev/cpu/31/cpuid. 1360 1361config HIGHMEM4G 1362 bool "High Memory Support" 1363 depends on X86_32 1364 help 1365 Linux can use up to 4 Gigabytes of physical memory on x86 systems. 1366 However, the address space of 32-bit x86 processors is only 4 1367 Gigabytes large. That means that, if you have a large amount of 1368 physical memory, not all of it can be "permanently mapped" by the 1369 kernel. The physical memory that's not permanently mapped is called 1370 "high memory". 1371 1372 If you are compiling a kernel which will never run on a machine with 1373 more than 1 Gigabyte total physical RAM, answer "off" here (default 1374 choice and suitable for most users). This will result in a "3GB/1GB" 1375 split: 3GB are mapped so that each process sees a 3GB virtual memory 1376 space and the remaining part of the 4GB virtual memory space is used 1377 by the kernel to permanently map as much physical memory as 1378 possible. 1379 1380 If the machine has between 1 and 4 Gigabytes physical RAM, then 1381 answer "Y" here. 1382 1383 If unsure, say N. 1384 1385choice 1386 prompt "Memory split" if EXPERT 1387 default VMSPLIT_3G 1388 depends on X86_32 1389 help 1390 Select the desired split between kernel and user memory. 1391 1392 If the address range available to the kernel is less than the 1393 physical memory installed, the remaining memory will be available 1394 as "high memory". Accessing high memory is a little more costly 1395 than low memory, as it needs to be mapped into the kernel first. 1396 Note that increasing the kernel address space limits the range 1397 available to user programs, making the address space there 1398 tighter. Selecting anything other than the default 3G/1G split 1399 will also likely make your kernel incompatible with binary-only 1400 kernel modules. 1401 1402 If you are not absolutely sure what you are doing, leave this 1403 option alone! 1404 1405 config VMSPLIT_3G 1406 bool "3G/1G user/kernel split" 1407 config VMSPLIT_3G_OPT 1408 depends on !X86_PAE 1409 bool "3G/1G user/kernel split (for full 1G low memory)" 1410 config VMSPLIT_2G 1411 bool "2G/2G user/kernel split" 1412 config VMSPLIT_2G_OPT 1413 depends on !X86_PAE 1414 bool "2G/2G user/kernel split (for full 2G low memory)" 1415 config VMSPLIT_1G 1416 bool "1G/3G user/kernel split" 1417endchoice 1418 1419config PAGE_OFFSET 1420 hex 1421 default 0xB0000000 if VMSPLIT_3G_OPT 1422 default 0x80000000 if VMSPLIT_2G 1423 default 0x78000000 if VMSPLIT_2G_OPT 1424 default 0x40000000 if VMSPLIT_1G 1425 default 0xC0000000 1426 depends on X86_32 1427 1428config HIGHMEM 1429 def_bool HIGHMEM4G 1430 1431config X86_PAE 1432 bool "PAE (Physical Address Extension) Support" 1433 depends on X86_32 && X86_HAVE_PAE 1434 select PHYS_ADDR_T_64BIT 1435 help 1436 PAE is required for NX support, and furthermore enables 1437 larger swapspace support for non-overcommit purposes. It 1438 has the cost of more pagetable lookup overhead, and also 1439 consumes more pagetable space per process. 1440 1441config X86_DIRECT_GBPAGES 1442 def_bool y 1443 depends on X86_64 1444 help 1445 Certain kernel features effectively disable kernel 1446 linear 1 GB mappings (even if the CPU otherwise 1447 supports them), so don't confuse the user by printing 1448 that we have them enabled. 1449 1450config X86_CPA_STATISTICS 1451 bool "Enable statistic for Change Page Attribute" 1452 depends on DEBUG_FS 1453 help 1454 Expose statistics about the Change Page Attribute mechanism, which 1455 helps to determine the effectiveness of preserving large and huge 1456 page mappings when mapping protections are changed. 1457 1458config X86_MEM_ENCRYPT 1459 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1460 select DYNAMIC_PHYSICAL_MASK 1461 def_bool n 1462 1463config AMD_MEM_ENCRYPT 1464 bool "AMD Secure Memory Encryption (SME) support" 1465 depends on X86_64 && CPU_SUP_AMD 1466 depends on EFI_STUB 1467 select DMA_COHERENT_POOL 1468 select ARCH_USE_MEMREMAP_PROT 1469 select INSTRUCTION_DECODER 1470 select ARCH_HAS_CC_PLATFORM 1471 select X86_MEM_ENCRYPT 1472 select UNACCEPTED_MEMORY 1473 select CRYPTO_LIB_AESGCM 1474 help 1475 Say yes to enable support for the encryption of system memory. 1476 This requires an AMD processor that supports Secure Memory 1477 Encryption (SME). 1478 1479# Common NUMA Features 1480config NUMA 1481 bool "NUMA Memory Allocation and Scheduler Support" 1482 depends on SMP 1483 depends on X86_64 1484 select USE_PERCPU_NUMA_NODE_ID 1485 select OF_NUMA if OF 1486 help 1487 Enable NUMA (Non-Uniform Memory Access) support. 1488 1489 The kernel will try to allocate memory used by a CPU on the 1490 local memory controller of the CPU and add some more 1491 NUMA awareness to the kernel. 1492 1493 For 64-bit this is recommended if the system is Intel Core i7 1494 (or later), AMD Opteron, or EM64T NUMA. 1495 1496 Otherwise, you should say N. 1497 1498config AMD_NUMA 1499 def_bool y 1500 prompt "Old style AMD Opteron NUMA detection" 1501 depends on X86_64 && NUMA && PCI 1502 help 1503 Enable AMD NUMA node topology detection. You should say Y here if 1504 you have a multi processor AMD system. This uses an old method to 1505 read the NUMA configuration directly from the builtin Northbridge 1506 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1507 which also takes priority if both are compiled in. 1508 1509config X86_64_ACPI_NUMA 1510 def_bool y 1511 prompt "ACPI NUMA detection" 1512 depends on X86_64 && NUMA && ACPI && PCI 1513 select ACPI_NUMA 1514 help 1515 Enable ACPI SRAT based node topology detection. 1516 1517config NODES_SHIFT 1518 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1519 range 1 10 1520 default "10" if MAXSMP 1521 default "6" if X86_64 1522 default "3" 1523 depends on NUMA 1524 help 1525 Specify the maximum number of NUMA Nodes available on the target 1526 system. Increases memory reserved to accommodate various tables. 1527 1528config ARCH_FLATMEM_ENABLE 1529 def_bool y 1530 depends on X86_32 && !NUMA 1531 1532config ARCH_SPARSEMEM_ENABLE 1533 def_bool y 1534 select SPARSEMEM_STATIC if X86_32 1535 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1536 select SPARSEMEM_VMEMMAP if X86_64 1537 1538config ARCH_SPARSEMEM_DEFAULT 1539 def_bool X86_64 || (NUMA && X86_32) 1540 1541config ARCH_SELECT_MEMORY_MODEL 1542 def_bool y 1543 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1544 1545config ARCH_MEMORY_PROBE 1546 bool "Enable sysfs memory/probe interface" 1547 depends on MEMORY_HOTPLUG 1548 help 1549 This option enables a sysfs memory/probe interface for testing. 1550 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1551 If you are unsure how to answer this question, answer N. 1552 1553config ARCH_PROC_KCORE_TEXT 1554 def_bool y 1555 depends on X86_64 && PROC_KCORE 1556 1557config ILLEGAL_POINTER_VALUE 1558 hex 1559 default 0 if X86_32 1560 default 0xdead000000000000 if X86_64 1561 1562config X86_PMEM_LEGACY_DEVICE 1563 bool 1564 1565config X86_PMEM_LEGACY 1566 tristate "Support non-standard NVDIMMs and ADR protected memory" 1567 depends on PHYS_ADDR_T_64BIT 1568 depends on BLK_DEV 1569 select X86_PMEM_LEGACY_DEVICE 1570 select NUMA_KEEP_MEMINFO if NUMA 1571 select LIBNVDIMM 1572 help 1573 Treat memory marked using the non-standard e820 type of 12 as used 1574 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1575 The kernel will offer these regions to the 'pmem' driver so 1576 they can be used for persistent storage. 1577 1578 Say Y if unsure. 1579 1580config X86_CHECK_BIOS_CORRUPTION 1581 bool "Check for low memory corruption" 1582 help 1583 Periodically check for memory corruption in low memory, which 1584 is suspected to be caused by BIOS. Even when enabled in the 1585 configuration, it is disabled at runtime. Enable it by 1586 setting "memory_corruption_check=1" on the kernel command 1587 line. By default it scans the low 64k of memory every 60 1588 seconds; see the memory_corruption_check_size and 1589 memory_corruption_check_period parameters in 1590 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1591 1592 When enabled with the default parameters, this option has 1593 almost no overhead, as it reserves a relatively small amount 1594 of memory and scans it infrequently. It both detects corruption 1595 and prevents it from affecting the running system. 1596 1597 It is, however, intended as a diagnostic tool; if repeatable 1598 BIOS-originated corruption always affects the same memory, 1599 you can use memmap= to prevent the kernel from using that 1600 memory. 1601 1602config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1603 bool "Set the default setting of memory_corruption_check" 1604 depends on X86_CHECK_BIOS_CORRUPTION 1605 default y 1606 help 1607 Set whether the default state of memory_corruption_check is 1608 on or off. 1609 1610config MATH_EMULATION 1611 bool 1612 depends on MODIFY_LDT_SYSCALL 1613 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1614 help 1615 Linux can emulate a math coprocessor (used for floating point 1616 operations) if you don't have one. 486DX and Pentium processors have 1617 a math coprocessor built in, 486SX and 386 do not, unless you added 1618 a 487DX or 387, respectively. (The messages during boot time can 1619 give you some hints here ["man dmesg"].) Everyone needs either a 1620 coprocessor or this emulation. 1621 1622 If you don't have a math coprocessor, you need to say Y here; if you 1623 say Y here even though you have a coprocessor, the coprocessor will 1624 be used nevertheless. (This behavior can be changed with the kernel 1625 command line option "no387", which comes handy if your coprocessor 1626 is broken. Try "man bootparam" or see the documentation of your boot 1627 loader (lilo or loadlin) about how to pass options to the kernel at 1628 boot time.) This means that it is a good idea to say Y here if you 1629 intend to use this kernel on different machines. 1630 1631 More information about the internals of the Linux math coprocessor 1632 emulation can be found in <file:arch/x86/math-emu/README>. 1633 1634 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1635 kernel, it won't hurt. 1636 1637config MTRR 1638 def_bool y 1639 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1640 help 1641 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1642 the Memory Type Range Registers (MTRRs) may be used to control 1643 processor access to memory ranges. This is most useful if you have 1644 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1645 allows bus write transfers to be combined into a larger transfer 1646 before bursting over the PCI/AGP bus. This can increase performance 1647 of image write operations 2.5 times or more. Saying Y here creates a 1648 /proc/mtrr file which may be used to manipulate your processor's 1649 MTRRs. Typically the X server should use this. 1650 1651 This code has a reasonably generic interface so that similar 1652 control registers on other processors can be easily supported 1653 as well: 1654 1655 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1656 Registers (ARRs) which provide a similar functionality to MTRRs. For 1657 these, the ARRs are used to emulate the MTRRs. 1658 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1659 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1660 write-combining. All of these processors are supported by this code 1661 and it makes sense to say Y here if you have one of them. 1662 1663 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1664 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1665 can lead to all sorts of problems, so it's good to say Y here. 1666 1667 You can safely say Y even if your machine doesn't have MTRRs, you'll 1668 just add about 9 KB to your kernel. 1669 1670 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1671 1672config MTRR_SANITIZER 1673 def_bool y 1674 prompt "MTRR cleanup support" 1675 depends on MTRR 1676 help 1677 Convert MTRR layout from continuous to discrete, so X drivers can 1678 add writeback entries. 1679 1680 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1681 The largest mtrr entry size for a continuous block can be set with 1682 mtrr_chunk_size. 1683 1684 If unsure, say Y. 1685 1686config MTRR_SANITIZER_ENABLE_DEFAULT 1687 int "MTRR cleanup enable value (0-1)" 1688 range 0 1 1689 default "0" 1690 depends on MTRR_SANITIZER 1691 help 1692 Enable mtrr cleanup default value 1693 1694config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1695 int "MTRR cleanup spare reg num (0-7)" 1696 range 0 7 1697 default "1" 1698 depends on MTRR_SANITIZER 1699 help 1700 mtrr cleanup spare entries default, it can be changed via 1701 mtrr_spare_reg_nr=N on the kernel command line. 1702 1703config X86_PAT 1704 def_bool y 1705 prompt "x86 PAT support" if EXPERT 1706 depends on MTRR 1707 select ARCH_USES_PG_ARCH_2 1708 help 1709 Use PAT attributes to setup page level cache control. 1710 1711 PATs are the modern equivalents of MTRRs and are much more 1712 flexible than MTRRs. 1713 1714 Say N here if you see bootup problems (boot crash, boot hang, 1715 spontaneous reboots) or a non-working video driver. 1716 1717 If unsure, say Y. 1718 1719config X86_UMIP 1720 def_bool y 1721 prompt "User Mode Instruction Prevention" if EXPERT 1722 help 1723 User Mode Instruction Prevention (UMIP) is a security feature in 1724 some x86 processors. If enabled, a general protection fault is 1725 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1726 executed in user mode. These instructions unnecessarily expose 1727 information about the hardware state. 1728 1729 The vast majority of applications do not use these instructions. 1730 For the very few that do, software emulation is provided in 1731 specific cases in protected and virtual-8086 modes. Emulated 1732 results are dummy. 1733 1734config CC_HAS_IBT 1735 # GCC >= 9 and binutils >= 2.29 1736 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1737 # Clang/LLVM >= 14 1738 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1739 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1740 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1741 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1742 $(as-instr,endbr64) 1743 1744config X86_CET 1745 def_bool n 1746 help 1747 CET features configured (Shadow stack or IBT) 1748 1749config X86_KERNEL_IBT 1750 prompt "Indirect Branch Tracking" 1751 def_bool y 1752 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1753 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1754 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1755 select OBJTOOL 1756 select X86_CET 1757 help 1758 Build the kernel with support for Indirect Branch Tracking, a 1759 hardware support course-grain forward-edge Control Flow Integrity 1760 protection. It enforces that all indirect calls must land on 1761 an ENDBR instruction, as such, the compiler will instrument the 1762 code with them to make this happen. 1763 1764 In addition to building the kernel with IBT, seal all functions that 1765 are not indirect call targets, avoiding them ever becoming one. 1766 1767 This requires LTO like objtool runs and will slow down the build. It 1768 does significantly reduce the number of ENDBR instructions in the 1769 kernel image. 1770 1771config X86_INTEL_MEMORY_PROTECTION_KEYS 1772 prompt "Memory Protection Keys" 1773 def_bool y 1774 # Note: only available in 64-bit mode 1775 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1776 select ARCH_USES_HIGH_VMA_FLAGS 1777 select ARCH_HAS_PKEYS 1778 help 1779 Memory Protection Keys provides a mechanism for enforcing 1780 page-based protections, but without requiring modification of the 1781 page tables when an application changes protection domains. 1782 1783 For details, see Documentation/core-api/protection-keys.rst 1784 1785 If unsure, say y. 1786 1787config ARCH_PKEY_BITS 1788 int 1789 default 4 1790 1791choice 1792 prompt "TSX enable mode" 1793 depends on CPU_SUP_INTEL 1794 default X86_INTEL_TSX_MODE_OFF 1795 help 1796 Intel's TSX (Transactional Synchronization Extensions) feature 1797 allows to optimize locking protocols through lock elision which 1798 can lead to a noticeable performance boost. 1799 1800 On the other hand it has been shown that TSX can be exploited 1801 to form side channel attacks (e.g. TAA) and chances are there 1802 will be more of those attacks discovered in the future. 1803 1804 Therefore TSX is not enabled by default (aka tsx=off). An admin 1805 might override this decision by tsx=on the command line parameter. 1806 Even with TSX enabled, the kernel will attempt to enable the best 1807 possible TAA mitigation setting depending on the microcode available 1808 for the particular machine. 1809 1810 This option allows to set the default tsx mode between tsx=on, =off 1811 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1812 details. 1813 1814 Say off if not sure, auto if TSX is in use but it should be used on safe 1815 platforms or on if TSX is in use and the security aspect of tsx is not 1816 relevant. 1817 1818config X86_INTEL_TSX_MODE_OFF 1819 bool "off" 1820 help 1821 TSX is disabled if possible - equals to tsx=off command line parameter. 1822 1823config X86_INTEL_TSX_MODE_ON 1824 bool "on" 1825 help 1826 TSX is always enabled on TSX capable HW - equals the tsx=on command 1827 line parameter. 1828 1829config X86_INTEL_TSX_MODE_AUTO 1830 bool "auto" 1831 help 1832 TSX is enabled on TSX capable HW that is believed to be safe against 1833 side channel attacks- equals the tsx=auto command line parameter. 1834endchoice 1835 1836config X86_SGX 1837 bool "Software Guard eXtensions (SGX)" 1838 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1839 select CRYPTO_LIB_SHA256 1840 select MMU_NOTIFIER 1841 select NUMA_KEEP_MEMINFO if NUMA 1842 select XARRAY_MULTI 1843 help 1844 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1845 that can be used by applications to set aside private regions of code 1846 and data, referred to as enclaves. An enclave's private memory can 1847 only be accessed by code running within the enclave. Accesses from 1848 outside the enclave, including other enclaves, are disallowed by 1849 hardware. 1850 1851 If unsure, say N. 1852 1853config X86_USER_SHADOW_STACK 1854 bool "X86 userspace shadow stack" 1855 depends on AS_WRUSS 1856 depends on X86_64 1857 select ARCH_USES_HIGH_VMA_FLAGS 1858 select ARCH_HAS_USER_SHADOW_STACK 1859 select X86_CET 1860 help 1861 Shadow stack protection is a hardware feature that detects function 1862 return address corruption. This helps mitigate ROP attacks. 1863 Applications must be enabled to use it, and old userspace does not 1864 get protection "for free". 1865 1866 CPUs supporting shadow stacks were first released in 2020. 1867 1868 See Documentation/arch/x86/shstk.rst for more information. 1869 1870 If unsure, say N. 1871 1872config INTEL_TDX_HOST 1873 bool "Intel Trust Domain Extensions (TDX) host support" 1874 depends on CPU_SUP_INTEL 1875 depends on X86_64 1876 depends on KVM_INTEL 1877 depends on X86_X2APIC 1878 select ARCH_KEEP_MEMBLOCK 1879 depends on CONTIG_ALLOC 1880 depends on !KEXEC_CORE 1881 depends on X86_MCE 1882 help 1883 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1884 host and certain physical attacks. This option enables necessary TDX 1885 support in the host kernel to run confidential VMs. 1886 1887 If unsure, say N. 1888 1889config EFI 1890 bool "EFI runtime service support" 1891 depends on ACPI 1892 select UCS2_STRING 1893 select EFI_RUNTIME_WRAPPERS 1894 select ARCH_USE_MEMREMAP_PROT 1895 select EFI_RUNTIME_MAP if KEXEC_CORE 1896 help 1897 This enables the kernel to use EFI runtime services that are 1898 available (such as the EFI variable services). 1899 1900 This option is only useful on systems that have EFI firmware. 1901 In addition, you should use the latest ELILO loader available 1902 at <http://elilo.sourceforge.net> in order to take advantage 1903 of EFI runtime services. However, even with this option, the 1904 resultant kernel should continue to boot on existing non-EFI 1905 platforms. 1906 1907config EFI_STUB 1908 bool "EFI stub support" 1909 depends on EFI 1910 select RELOCATABLE 1911 help 1912 This kernel feature allows a bzImage to be loaded directly 1913 by EFI firmware without the use of a bootloader. 1914 1915 See Documentation/admin-guide/efi-stub.rst for more information. 1916 1917config EFI_HANDOVER_PROTOCOL 1918 bool "EFI handover protocol (DEPRECATED)" 1919 depends on EFI_STUB 1920 default y 1921 help 1922 Select this in order to include support for the deprecated EFI 1923 handover protocol, which defines alternative entry points into the 1924 EFI stub. This is a practice that has no basis in the UEFI 1925 specification, and requires a priori knowledge on the part of the 1926 bootloader about Linux/x86 specific ways of passing the command line 1927 and initrd, and where in memory those assets may be loaded. 1928 1929 If in doubt, say Y. Even though the corresponding support is not 1930 present in upstream GRUB or other bootloaders, most distros build 1931 GRUB with numerous downstream patches applied, and may rely on the 1932 handover protocol as as result. 1933 1934config EFI_MIXED 1935 bool "EFI mixed-mode support" 1936 depends on EFI_STUB && X86_64 1937 help 1938 Enabling this feature allows a 64-bit kernel to be booted 1939 on a 32-bit firmware, provided that your CPU supports 64-bit 1940 mode. 1941 1942 Note that it is not possible to boot a mixed-mode enabled 1943 kernel via the EFI boot stub - a bootloader that supports 1944 the EFI handover protocol must be used. 1945 1946 If unsure, say N. 1947 1948config EFI_RUNTIME_MAP 1949 bool "Export EFI runtime maps to sysfs" if EXPERT 1950 depends on EFI 1951 help 1952 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 1953 That memory map is required by the 2nd kernel to set up EFI virtual 1954 mappings after kexec, but can also be used for debugging purposes. 1955 1956 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 1957 1958source "kernel/Kconfig.hz" 1959 1960config ARCH_SUPPORTS_KEXEC 1961 def_bool y 1962 1963config ARCH_SUPPORTS_KEXEC_FILE 1964 def_bool X86_64 1965 1966config ARCH_SELECTS_KEXEC_FILE 1967 def_bool y 1968 depends on KEXEC_FILE 1969 select HAVE_IMA_KEXEC if IMA 1970 1971config ARCH_SUPPORTS_KEXEC_PURGATORY 1972 def_bool y 1973 1974config ARCH_SUPPORTS_KEXEC_SIG 1975 def_bool y 1976 1977config ARCH_SUPPORTS_KEXEC_SIG_FORCE 1978 def_bool y 1979 1980config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 1981 def_bool y 1982 1983config ARCH_SUPPORTS_KEXEC_JUMP 1984 def_bool y 1985 1986config ARCH_SUPPORTS_KEXEC_HANDOVER 1987 def_bool X86_64 1988 1989config ARCH_SUPPORTS_CRASH_DUMP 1990 def_bool X86_64 || (X86_32 && HIGHMEM) 1991 1992config ARCH_DEFAULT_CRASH_DUMP 1993 def_bool y 1994 1995config ARCH_SUPPORTS_CRASH_HOTPLUG 1996 def_bool y 1997 1998config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 1999 def_bool CRASH_RESERVE 2000 2001config PHYSICAL_START 2002 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2003 default "0x1000000" 2004 help 2005 This gives the physical address where the kernel is loaded. 2006 2007 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2008 will decompress itself to above physical address and run from there. 2009 Otherwise, bzImage will run from the address where it has been loaded 2010 by the boot loader. The only exception is if it is loaded below the 2011 above physical address, in which case it will relocate itself there. 2012 2013 In normal kdump cases one does not have to set/change this option 2014 as now bzImage can be compiled as a completely relocatable image 2015 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2016 address. This option is mainly useful for the folks who don't want 2017 to use a bzImage for capturing the crash dump and want to use a 2018 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2019 to be specifically compiled to run from a specific memory area 2020 (normally a reserved region) and this option comes handy. 2021 2022 So if you are using bzImage for capturing the crash dump, 2023 leave the value here unchanged to 0x1000000 and set 2024 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2025 for capturing the crash dump change this value to start of 2026 the reserved region. In other words, it can be set based on 2027 the "X" value as specified in the "crashkernel=YM@XM" 2028 command line boot parameter passed to the panic-ed 2029 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2030 for more details about crash dumps. 2031 2032 Usage of bzImage for capturing the crash dump is recommended as 2033 one does not have to build two kernels. Same kernel can be used 2034 as production kernel and capture kernel. Above option should have 2035 gone away after relocatable bzImage support is introduced. But it 2036 is present because there are users out there who continue to use 2037 vmlinux for dump capture. This option should go away down the 2038 line. 2039 2040 Don't change this unless you know what you are doing. 2041 2042config RELOCATABLE 2043 bool "Build a relocatable kernel" 2044 default y 2045 help 2046 This builds a kernel image that retains relocation information 2047 so it can be loaded someplace besides the default 1MB. 2048 The relocations tend to make the kernel binary about 10% larger, 2049 but are discarded at runtime. 2050 2051 One use is for the kexec on panic case where the recovery kernel 2052 must live at a different physical address than the primary 2053 kernel. 2054 2055 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2056 it has been loaded at and the compile time physical address 2057 (CONFIG_PHYSICAL_START) is used as the minimum location. 2058 2059config RANDOMIZE_BASE 2060 bool "Randomize the address of the kernel image (KASLR)" 2061 depends on RELOCATABLE 2062 default y 2063 help 2064 In support of Kernel Address Space Layout Randomization (KASLR), 2065 this randomizes the physical address at which the kernel image 2066 is decompressed and the virtual address where the kernel 2067 image is mapped, as a security feature that deters exploit 2068 attempts relying on knowledge of the location of kernel 2069 code internals. 2070 2071 On 64-bit, the kernel physical and virtual addresses are 2072 randomized separately. The physical address will be anywhere 2073 between 16MB and the top of physical memory (up to 64TB). The 2074 virtual address will be randomized from 16MB up to 1GB (9 bits 2075 of entropy). Note that this also reduces the memory space 2076 available to kernel modules from 1.5GB to 1GB. 2077 2078 On 32-bit, the kernel physical and virtual addresses are 2079 randomized together. They will be randomized from 16MB up to 2080 512MB (8 bits of entropy). 2081 2082 Entropy is generated using the RDRAND instruction if it is 2083 supported. If RDTSC is supported, its value is mixed into 2084 the entropy pool as well. If neither RDRAND nor RDTSC are 2085 supported, then entropy is read from the i8254 timer. The 2086 usable entropy is limited by the kernel being built using 2087 2GB addressing, and that PHYSICAL_ALIGN must be at a 2088 minimum of 2MB. As a result, only 10 bits of entropy are 2089 theoretically possible, but the implementations are further 2090 limited due to memory layouts. 2091 2092 If unsure, say Y. 2093 2094# Relocation on x86 needs some additional build support 2095config X86_NEED_RELOCS 2096 def_bool y 2097 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2098 select ARCH_VMLINUX_NEEDS_RELOCS 2099 2100config PHYSICAL_ALIGN 2101 hex "Alignment value to which kernel should be aligned" 2102 default "0x200000" 2103 range 0x2000 0x1000000 if X86_32 2104 range 0x200000 0x1000000 if X86_64 2105 help 2106 This value puts the alignment restrictions on physical address 2107 where kernel is loaded and run from. Kernel is compiled for an 2108 address which meets above alignment restriction. 2109 2110 If bootloader loads the kernel at a non-aligned address and 2111 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2112 address aligned to above value and run from there. 2113 2114 If bootloader loads the kernel at a non-aligned address and 2115 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2116 load address and decompress itself to the address it has been 2117 compiled for and run from there. The address for which kernel is 2118 compiled already meets above alignment restrictions. Hence the 2119 end result is that kernel runs from a physical address meeting 2120 above alignment restrictions. 2121 2122 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2123 this value must be a multiple of 0x200000. 2124 2125 Don't change this unless you know what you are doing. 2126 2127config RANDOMIZE_MEMORY 2128 bool "Randomize the kernel memory sections" 2129 depends on X86_64 2130 depends on RANDOMIZE_BASE 2131 default RANDOMIZE_BASE 2132 help 2133 Randomizes the base virtual address of kernel memory sections 2134 (physical memory mapping, vmalloc & vmemmap). This security feature 2135 makes exploits relying on predictable memory locations less reliable. 2136 2137 The order of allocations remains unchanged. Entropy is generated in 2138 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2139 configuration have in average 30,000 different possible virtual 2140 addresses for each memory section. 2141 2142 If unsure, say Y. 2143 2144config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2145 hex "Physical memory mapping padding" if EXPERT 2146 depends on RANDOMIZE_MEMORY 2147 default "0xa" if MEMORY_HOTPLUG 2148 default "0x0" 2149 range 0x1 0x40 if MEMORY_HOTPLUG 2150 range 0x0 0x40 2151 help 2152 Define the padding in terabytes added to the existing physical 2153 memory size during kernel memory randomization. It is useful 2154 for memory hotplug support but reduces the entropy available for 2155 address randomization. 2156 2157 If unsure, leave at the default value. 2158 2159config ADDRESS_MASKING 2160 bool "Linear Address Masking support" 2161 depends on X86_64 2162 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2163 help 2164 Linear Address Masking (LAM) modifies the checking that is applied 2165 to 64-bit linear addresses, allowing software to use of the 2166 untranslated address bits for metadata. 2167 2168 The capability can be used for efficient address sanitizers (ASAN) 2169 implementation and for optimizations in JITs. 2170 2171config HOTPLUG_CPU 2172 def_bool y 2173 depends on SMP 2174 2175config COMPAT_VDSO 2176 def_bool n 2177 prompt "Workaround for glibc 2.3.2 / 2.3.3 (released in year 2003/2004)" 2178 depends on COMPAT_32 2179 help 2180 Certain buggy versions of glibc will crash if they are 2181 presented with a 32-bit vDSO that is not mapped at the address 2182 indicated in its segment table. 2183 2184 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2185 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2186 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2187 the only released version with the bug, but OpenSUSE 9 2188 contains a buggy "glibc 2.3.2". 2189 2190 The symptom of the bug is that everything crashes on startup, saying: 2191 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2192 2193 Saying Y here changes the default value of the vdso32 boot 2194 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2195 This works around the glibc bug but hurts performance. 2196 2197 If unsure, say N: if you are compiling your own kernel, you 2198 are unlikely to be using a buggy version of glibc. 2199 2200choice 2201 prompt "vsyscall table for legacy applications" 2202 depends on X86_64 2203 default LEGACY_VSYSCALL_XONLY 2204 help 2205 Legacy user code that does not know how to find the vDSO expects 2206 to be able to issue three syscalls by calling fixed addresses in 2207 kernel space. Since this location is not randomized with ASLR, 2208 it can be used to assist security vulnerability exploitation. 2209 2210 This setting can be changed at boot time via the kernel command 2211 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2212 is deprecated and can only be enabled using the kernel command 2213 line. 2214 2215 On a system with recent enough glibc (2.14 or newer) and no 2216 static binaries, you can say None without a performance penalty 2217 to improve security. 2218 2219 If unsure, select "Emulate execution only". 2220 2221 config LEGACY_VSYSCALL_XONLY 2222 bool "Emulate execution only" 2223 help 2224 The kernel traps and emulates calls into the fixed vsyscall 2225 address mapping and does not allow reads. This 2226 configuration is recommended when userspace might use the 2227 legacy vsyscall area but support for legacy binary 2228 instrumentation of legacy code is not needed. It mitigates 2229 certain uses of the vsyscall area as an ASLR-bypassing 2230 buffer. 2231 2232 config LEGACY_VSYSCALL_NONE 2233 bool "None" 2234 help 2235 There will be no vsyscall mapping at all. This will 2236 eliminate any risk of ASLR bypass due to the vsyscall 2237 fixed address mapping. Attempts to use the vsyscalls 2238 will be reported to dmesg, so that either old or 2239 malicious userspace programs can be identified. 2240 2241endchoice 2242 2243config CMDLINE_BOOL 2244 bool "Built-in kernel command line" 2245 help 2246 Allow for specifying boot arguments to the kernel at 2247 build time. On some systems (e.g. embedded ones), it is 2248 necessary or convenient to provide some or all of the 2249 kernel boot arguments with the kernel itself (that is, 2250 to not rely on the boot loader to provide them.) 2251 2252 To compile command line arguments into the kernel, 2253 set this option to 'Y', then fill in the 2254 boot arguments in CONFIG_CMDLINE. 2255 2256 Systems with fully functional boot loaders (i.e. non-embedded) 2257 should leave this option set to 'N'. 2258 2259config CMDLINE 2260 string "Built-in kernel command string" 2261 depends on CMDLINE_BOOL 2262 default "" 2263 help 2264 Enter arguments here that should be compiled into the kernel 2265 image and used at boot time. If the boot loader provides a 2266 command line at boot time, it is appended to this string to 2267 form the full kernel command line, when the system boots. 2268 2269 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2270 change this behavior. 2271 2272 In most cases, the command line (whether built-in or provided 2273 by the boot loader) should specify the device for the root 2274 file system. 2275 2276config CMDLINE_OVERRIDE 2277 bool "Built-in command line overrides boot loader arguments" 2278 depends on CMDLINE_BOOL && CMDLINE != "" 2279 help 2280 Set this option to 'Y' to have the kernel ignore the boot loader 2281 command line, and use ONLY the built-in command line. 2282 2283 This is used to work around broken boot loaders. This should 2284 be set to 'N' under normal conditions. 2285 2286config MODIFY_LDT_SYSCALL 2287 bool "Enable the LDT (local descriptor table)" if EXPERT 2288 default y 2289 help 2290 Linux can allow user programs to install a per-process x86 2291 Local Descriptor Table (LDT) using the modify_ldt(2) system 2292 call. This is required to run 16-bit or segmented code such as 2293 DOSEMU or some Wine programs. It is also used by some very old 2294 threading libraries. 2295 2296 Enabling this feature adds a small amount of overhead to 2297 context switches and increases the low-level kernel attack 2298 surface. Disabling it removes the modify_ldt(2) system call. 2299 2300 Saying 'N' here may make sense for embedded or server kernels. 2301 2302config STRICT_SIGALTSTACK_SIZE 2303 bool "Enforce strict size checking for sigaltstack" 2304 depends on DYNAMIC_SIGFRAME 2305 help 2306 For historical reasons MINSIGSTKSZ is a constant which became 2307 already too small with AVX512 support. Add a mechanism to 2308 enforce strict checking of the sigaltstack size against the 2309 real size of the FPU frame. This option enables the check 2310 by default. It can also be controlled via the kernel command 2311 line option 'strict_sas_size' independent of this config 2312 switch. Enabling it might break existing applications which 2313 allocate a too small sigaltstack but 'work' because they 2314 never get a signal delivered. 2315 2316 Say 'N' unless you want to really enforce this check. 2317 2318config CFI_AUTO_DEFAULT 2319 bool "Attempt to use FineIBT by default at boot time" 2320 depends on FINEIBT 2321 depends on !RUST || RUSTC_VERSION >= 108800 2322 default y 2323 help 2324 Attempt to use FineIBT by default at boot time. If enabled, 2325 this is the same as booting with "cfi=auto". If disabled, 2326 this is the same as booting with "cfi=kcfi". 2327 2328source "kernel/livepatch/Kconfig" 2329 2330config X86_BUS_LOCK_DETECT 2331 bool "Split Lock Detect and Bus Lock Detect support" 2332 depends on CPU_SUP_INTEL || CPU_SUP_AMD 2333 default y 2334 help 2335 Enable Split Lock Detect and Bus Lock Detect functionalities. 2336 See <file:Documentation/arch/x86/buslock.rst> for more information. 2337 2338endmenu 2339 2340config CC_HAS_NAMED_AS 2341 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null) 2342 depends on CC_IS_GCC 2343 2344# 2345# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN) 2346# are incompatible with named address spaces with GCC < 13.3 2347# (see GCC PR sanitizer/111736 and also PR sanitizer/115172). 2348# 2349 2350config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2351 def_bool y 2352 depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300 2353 depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200 2354 2355config USE_X86_SEG_SUPPORT 2356 def_bool CC_HAS_NAMED_AS 2357 depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS 2358 2359config CC_HAS_SLS 2360 def_bool $(cc-option,-mharden-sls=all) 2361 2362config CC_HAS_RETURN_THUNK 2363 def_bool $(cc-option,-mfunction-return=thunk-extern) 2364 2365config CC_HAS_ENTRY_PADDING 2366 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2367 2368config CC_HAS_KCFI_ARITY 2369 def_bool $(cc-option,-fsanitize=kcfi -fsanitize-kcfi-arity) 2370 depends on CC_IS_CLANG && !RUST 2371 2372config FUNCTION_PADDING_CFI 2373 int 2374 default 59 if FUNCTION_ALIGNMENT_64B 2375 default 27 if FUNCTION_ALIGNMENT_32B 2376 default 11 if FUNCTION_ALIGNMENT_16B 2377 default 3 if FUNCTION_ALIGNMENT_8B 2378 default 0 2379 2380# Basically: FUNCTION_ALIGNMENT - 5*CFI 2381# except Kconfig can't do arithmetic :/ 2382config FUNCTION_PADDING_BYTES 2383 int 2384 default FUNCTION_PADDING_CFI if CFI 2385 default FUNCTION_ALIGNMENT 2386 2387config CALL_PADDING 2388 def_bool n 2389 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2390 select FUNCTION_ALIGNMENT_16B 2391 2392config FINEIBT 2393 def_bool y 2394 depends on X86_KERNEL_IBT && CFI && MITIGATION_RETPOLINE 2395 select CALL_PADDING 2396 2397config FINEIBT_BHI 2398 def_bool y 2399 depends on FINEIBT && CC_HAS_KCFI_ARITY 2400 2401config HAVE_CALL_THUNKS 2402 def_bool y 2403 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2404 2405config CALL_THUNKS 2406 def_bool n 2407 select CALL_PADDING 2408 2409config PREFIX_SYMBOLS 2410 def_bool y 2411 depends on CALL_PADDING && !CFI 2412 2413menuconfig CPU_MITIGATIONS 2414 bool "Mitigations for CPU vulnerabilities" 2415 default y 2416 help 2417 Say Y here to enable options which enable mitigations for hardware 2418 vulnerabilities (usually related to speculative execution). 2419 Mitigations can be disabled or restricted to SMT systems at runtime 2420 via the "mitigations" kernel parameter. 2421 2422 If you say N, all mitigations will be disabled. This CANNOT be 2423 overridden at runtime. 2424 2425 Say 'Y', unless you really know what you are doing. 2426 2427if CPU_MITIGATIONS 2428 2429config MITIGATION_PAGE_TABLE_ISOLATION 2430 bool "Remove the kernel mapping in user mode" 2431 default y 2432 depends on (X86_64 || X86_PAE) 2433 help 2434 This feature reduces the number of hardware side channels by 2435 ensuring that the majority of kernel addresses are not mapped 2436 into userspace. 2437 2438 See Documentation/arch/x86/pti.rst for more details. 2439 2440config MITIGATION_RETPOLINE 2441 bool "Avoid speculative indirect branches in kernel" 2442 select OBJTOOL if HAVE_OBJTOOL 2443 default y 2444 help 2445 Compile kernel with the retpoline compiler options to guard against 2446 kernel-to-user data leaks by avoiding speculative indirect 2447 branches. Requires a compiler with -mindirect-branch=thunk-extern 2448 support for full protection. The kernel may run slower. 2449 2450config MITIGATION_RETHUNK 2451 bool "Enable return-thunks" 2452 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2453 select OBJTOOL if HAVE_OBJTOOL 2454 default y if X86_64 2455 help 2456 Compile the kernel with the return-thunks compiler option to guard 2457 against kernel-to-user data leaks by avoiding return speculation. 2458 Requires a compiler with -mfunction-return=thunk-extern 2459 support for full protection. The kernel may run slower. 2460 2461config MITIGATION_UNRET_ENTRY 2462 bool "Enable UNRET on kernel entry" 2463 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2464 default y 2465 help 2466 Compile the kernel with support for the retbleed=unret mitigation. 2467 2468config MITIGATION_CALL_DEPTH_TRACKING 2469 bool "Mitigate RSB underflow with call depth tracking" 2470 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2471 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2472 select CALL_THUNKS 2473 default y 2474 help 2475 Compile the kernel with call depth tracking to mitigate the Intel 2476 SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off 2477 by default and needs to be enabled on the kernel command line via the 2478 retbleed=stuff option. For non-affected systems the overhead of this 2479 option is marginal as the call depth tracking is using run-time 2480 generated call thunks in a compiler generated padding area and call 2481 patching. This increases text size by ~5%. For non affected systems 2482 this space is unused. On affected SKL systems this results in a 2483 significant performance gain over the IBRS mitigation. 2484 2485config CALL_THUNKS_DEBUG 2486 bool "Enable call thunks and call depth tracking debugging" 2487 depends on MITIGATION_CALL_DEPTH_TRACKING 2488 select FUNCTION_ALIGNMENT_32B 2489 default n 2490 help 2491 Enable call/ret counters for imbalance detection and build in 2492 a noisy dmesg about callthunks generation and call patching for 2493 trouble shooting. The debug prints need to be enabled on the 2494 kernel command line with 'debug-callthunks'. 2495 Only enable this when you are debugging call thunks as this 2496 creates a noticeable runtime overhead. If unsure say N. 2497 2498config MITIGATION_IBPB_ENTRY 2499 bool "Enable IBPB on kernel entry" 2500 depends on CPU_SUP_AMD && X86_64 2501 default y 2502 help 2503 Compile the kernel with support for the retbleed=ibpb and 2504 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations. 2505 2506config MITIGATION_IBRS_ENTRY 2507 bool "Enable IBRS on kernel entry" 2508 depends on CPU_SUP_INTEL && X86_64 2509 default y 2510 help 2511 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2512 This mitigates both spectre_v2 and retbleed at great cost to 2513 performance. 2514 2515config MITIGATION_SRSO 2516 bool "Mitigate speculative RAS overflow on AMD" 2517 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2518 default y 2519 help 2520 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2521 2522config MITIGATION_SLS 2523 bool "Mitigate Straight-Line-Speculation" 2524 depends on CC_HAS_SLS && X86_64 2525 select OBJTOOL if HAVE_OBJTOOL 2526 default n 2527 help 2528 Compile the kernel with straight-line-speculation options to guard 2529 against straight line speculation. The kernel image might be slightly 2530 larger. 2531 2532config MITIGATION_GDS 2533 bool "Mitigate Gather Data Sampling" 2534 depends on CPU_SUP_INTEL 2535 default y 2536 help 2537 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware 2538 vulnerability which allows unprivileged speculative access to data 2539 which was previously stored in vector registers. The attacker uses gather 2540 instructions to infer the stale vector register data. 2541 2542config MITIGATION_RFDS 2543 bool "RFDS Mitigation" 2544 depends on CPU_SUP_INTEL 2545 default y 2546 help 2547 Enable mitigation for Register File Data Sampling (RFDS) by default. 2548 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2549 allows unprivileged speculative access to stale data previously 2550 stored in floating point, vector and integer registers. 2551 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2552 2553config MITIGATION_SPECTRE_BHI 2554 bool "Mitigate Spectre-BHB (Branch History Injection)" 2555 depends on CPU_SUP_INTEL 2556 default y 2557 help 2558 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2559 where the branch history buffer is poisoned to speculatively steer 2560 indirect branches. 2561 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2562 2563config MITIGATION_MDS 2564 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug" 2565 depends on CPU_SUP_INTEL 2566 default y 2567 help 2568 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is 2569 a hardware vulnerability which allows unprivileged speculative access 2570 to data which is available in various CPU internal buffers. 2571 See also <file:Documentation/admin-guide/hw-vuln/mds.rst> 2572 2573config MITIGATION_TAA 2574 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug" 2575 depends on CPU_SUP_INTEL 2576 default y 2577 help 2578 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware 2579 vulnerability that allows unprivileged speculative access to data 2580 which is available in various CPU internal buffers by using 2581 asynchronous aborts within an Intel TSX transactional region. 2582 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst> 2583 2584config MITIGATION_MMIO_STALE_DATA 2585 bool "Mitigate MMIO Stale Data hardware bug" 2586 depends on CPU_SUP_INTEL 2587 default y 2588 help 2589 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO 2590 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO) 2591 vulnerabilities that can expose data. The vulnerabilities require the 2592 attacker to have access to MMIO. 2593 See also 2594 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst> 2595 2596config MITIGATION_L1TF 2597 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug" 2598 depends on CPU_SUP_INTEL 2599 default y 2600 help 2601 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a 2602 hardware vulnerability which allows unprivileged speculative access to data 2603 available in the Level 1 Data Cache. 2604 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst 2605 2606config MITIGATION_RETBLEED 2607 bool "Mitigate RETBleed hardware bug" 2608 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY 2609 default y 2610 help 2611 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution 2612 with Return Instructions) vulnerability. RETBleed is a speculative 2613 execution attack which takes advantage of microarchitectural behavior 2614 in many modern microprocessors, similar to Spectre v2. An 2615 unprivileged attacker can use these flaws to bypass conventional 2616 memory security restrictions to gain read access to privileged memory 2617 that would otherwise be inaccessible. 2618 2619config MITIGATION_SPECTRE_V1 2620 bool "Mitigate SPECTRE V1 hardware bug" 2621 default y 2622 help 2623 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a 2624 class of side channel attacks that takes advantage of speculative 2625 execution that bypasses conditional branch instructions used for 2626 memory access bounds check. 2627 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2628 2629config MITIGATION_SPECTRE_V2 2630 bool "Mitigate SPECTRE V2 hardware bug" 2631 default y 2632 help 2633 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre 2634 V2 is a class of side channel attacks that takes advantage of 2635 indirect branch predictors inside the processor. In Spectre variant 2 2636 attacks, the attacker can steer speculative indirect branches in the 2637 victim to gadget code by poisoning the branch target buffer of a CPU 2638 used for predicting indirect branch addresses. 2639 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2640 2641config MITIGATION_SRBDS 2642 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug" 2643 depends on CPU_SUP_INTEL 2644 default y 2645 help 2646 Enable mitigation for Special Register Buffer Data Sampling (SRBDS). 2647 SRBDS is a hardware vulnerability that allows Microarchitectural Data 2648 Sampling (MDS) techniques to infer values returned from special 2649 register accesses. An unprivileged user can extract values returned 2650 from RDRAND and RDSEED executed on another core or sibling thread 2651 using MDS techniques. 2652 See also 2653 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst> 2654 2655config MITIGATION_SSB 2656 bool "Mitigate Speculative Store Bypass (SSB) hardware bug" 2657 default y 2658 help 2659 Enable mitigation for Speculative Store Bypass (SSB). SSB is a 2660 hardware security vulnerability and its exploitation takes advantage 2661 of speculative execution in a similar way to the Meltdown and Spectre 2662 security vulnerabilities. 2663 2664config MITIGATION_ITS 2665 bool "Enable Indirect Target Selection mitigation" 2666 depends on CPU_SUP_INTEL && X86_64 2667 depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK 2668 select EXECMEM 2669 default y 2670 help 2671 Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in 2672 BPU on some Intel CPUs that may allow Spectre V2 style attacks. If 2673 disabled, mitigation cannot be enabled via cmdline. 2674 See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst> 2675 2676config MITIGATION_TSA 2677 bool "Mitigate Transient Scheduler Attacks" 2678 depends on CPU_SUP_AMD 2679 default y 2680 help 2681 Enable mitigation for Transient Scheduler Attacks. TSA is a hardware 2682 security vulnerability on AMD CPUs which can lead to forwarding of 2683 invalid info to subsequent instructions and thus can affect their 2684 timing and thereby cause a leakage. 2685 2686config MITIGATION_VMSCAPE 2687 bool "Mitigate VMSCAPE" 2688 depends on KVM 2689 default y 2690 help 2691 Enable mitigation for VMSCAPE attacks. VMSCAPE is a hardware security 2692 vulnerability on Intel and AMD CPUs that may allow a guest to do 2693 Spectre v2 style attacks on userspace hypervisor. 2694endif 2695 2696config ARCH_HAS_ADD_PAGES 2697 def_bool y 2698 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2699 2700menu "Power management and ACPI options" 2701 2702config ARCH_HIBERNATION_HEADER 2703 def_bool y 2704 depends on HIBERNATION 2705 2706source "kernel/power/Kconfig" 2707 2708source "drivers/acpi/Kconfig" 2709 2710config X86_APM_BOOT 2711 def_bool y 2712 depends on APM 2713 2714menuconfig APM 2715 tristate "APM (Advanced Power Management) BIOS support" 2716 depends on X86_32 && PM_SLEEP 2717 help 2718 APM is a BIOS specification for saving power using several different 2719 techniques. This is mostly useful for battery powered laptops with 2720 APM compliant BIOSes. If you say Y here, the system time will be 2721 reset after a RESUME operation, the /proc/apm device will provide 2722 battery status information, and user-space programs will receive 2723 notification of APM "events" (e.g. battery status change). 2724 2725 If you select "Y" here, you can disable actual use of the APM 2726 BIOS by passing the "apm=off" option to the kernel at boot time. 2727 2728 Note that the APM support is almost completely disabled for 2729 machines with more than one CPU. 2730 2731 In order to use APM, you will need supporting software. For location 2732 and more information, read <file:Documentation/power/apm-acpi.rst> 2733 and the Battery Powered Linux mini-HOWTO, available from 2734 <http://www.tldp.org/docs.html#howto>. 2735 2736 This driver does not spin down disk drives (see the hdparm(8) 2737 manpage ("man 8 hdparm") for that), and it doesn't turn off 2738 VESA-compliant "green" monitors. 2739 2740 This driver does not support the TI 4000M TravelMate and the ACER 2741 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2742 desktop machines also don't have compliant BIOSes, and this driver 2743 may cause those machines to panic during the boot phase. 2744 2745 Generally, if you don't have a battery in your machine, there isn't 2746 much point in using this driver and you should say N. If you get 2747 random kernel OOPSes or reboots that don't seem to be related to 2748 anything, try disabling/enabling this option (or disabling/enabling 2749 APM in your BIOS). 2750 2751 Some other things you should try when experiencing seemingly random, 2752 "weird" problems: 2753 2754 1) make sure that you have enough swap space and that it is 2755 enabled. 2756 2) pass the "idle=poll" option to the kernel 2757 3) switch on floating point emulation in the kernel and pass 2758 the "no387" option to the kernel 2759 4) pass the "floppy=nodma" option to the kernel 2760 5) pass the "mem=4M" option to the kernel (thereby disabling 2761 all but the first 4 MB of RAM) 2762 6) make sure that the CPU is not over clocked. 2763 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2764 8) disable the cache from your BIOS settings 2765 9) install a fan for the video card or exchange video RAM 2766 10) install a better fan for the CPU 2767 11) exchange RAM chips 2768 12) exchange the motherboard. 2769 2770 To compile this driver as a module, choose M here: the 2771 module will be called apm. 2772 2773if APM 2774 2775config APM_IGNORE_USER_SUSPEND 2776 bool "Ignore USER SUSPEND" 2777 help 2778 This option will ignore USER SUSPEND requests. On machines with a 2779 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2780 series notebooks, it is necessary to say Y because of a BIOS bug. 2781 2782config APM_DO_ENABLE 2783 bool "Enable PM at boot time" 2784 help 2785 Enable APM features at boot time. From page 36 of the APM BIOS 2786 specification: "When disabled, the APM BIOS does not automatically 2787 power manage devices, enter the Standby State, enter the Suspend 2788 State, or take power saving steps in response to CPU Idle calls." 2789 This driver will make CPU Idle calls when Linux is idle (unless this 2790 feature is turned off -- see "Do CPU IDLE calls", below). This 2791 should always save battery power, but more complicated APM features 2792 will be dependent on your BIOS implementation. You may need to turn 2793 this option off if your computer hangs at boot time when using APM 2794 support, or if it beeps continuously instead of suspending. Turn 2795 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2796 T400CDT. This is off by default since most machines do fine without 2797 this feature. 2798 2799config APM_CPU_IDLE 2800 depends on CPU_IDLE 2801 bool "Make CPU Idle calls when idle" 2802 help 2803 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2804 On some machines, this can activate improved power savings, such as 2805 a slowed CPU clock rate, when the machine is idle. These idle calls 2806 are made after the idle loop has run for some length of time (e.g., 2807 333 mS). On some machines, this will cause a hang at boot time or 2808 whenever the CPU becomes idle. (On machines with more than one CPU, 2809 this option does nothing.) 2810 2811config APM_DISPLAY_BLANK 2812 bool "Enable console blanking using APM" 2813 help 2814 Enable console blanking using the APM. Some laptops can use this to 2815 turn off the LCD backlight when the screen blanker of the Linux 2816 virtual console blanks the screen. Note that this is only used by 2817 the virtual console screen blanker, and won't turn off the backlight 2818 when using the X Window system. This also doesn't have anything to 2819 do with your VESA-compliant power-saving monitor. Further, this 2820 option doesn't work for all laptops -- it might not turn off your 2821 backlight at all, or it might print a lot of errors to the console, 2822 especially if you are using gpm. 2823 2824config APM_ALLOW_INTS 2825 bool "Allow interrupts during APM BIOS calls" 2826 help 2827 Normally we disable external interrupts while we are making calls to 2828 the APM BIOS as a measure to lessen the effects of a badly behaving 2829 BIOS implementation. The BIOS should reenable interrupts if it 2830 needs to. Unfortunately, some BIOSes do not -- especially those in 2831 many of the newer IBM Thinkpads. If you experience hangs when you 2832 suspend, try setting this to Y. Otherwise, say N. 2833 2834endif # APM 2835 2836source "drivers/cpufreq/Kconfig" 2837 2838source "drivers/cpuidle/Kconfig" 2839 2840source "drivers/idle/Kconfig" 2841 2842endmenu 2843 2844menu "Bus options (PCI etc.)" 2845 2846choice 2847 prompt "PCI access mode" 2848 depends on X86_32 && PCI 2849 default PCI_GOANY 2850 help 2851 On PCI systems, the BIOS can be used to detect the PCI devices and 2852 determine their configuration. However, some old PCI motherboards 2853 have BIOS bugs and may crash if this is done. Also, some embedded 2854 PCI-based systems don't have any BIOS at all. Linux can also try to 2855 detect the PCI hardware directly without using the BIOS. 2856 2857 With this option, you can specify how Linux should detect the 2858 PCI devices. If you choose "BIOS", the BIOS will be used, 2859 if you choose "Direct", the BIOS won't be used, and if you 2860 choose "MMConfig", then PCI Express MMCONFIG will be used. 2861 If you choose "Any", the kernel will try MMCONFIG, then the 2862 direct access method and falls back to the BIOS if that doesn't 2863 work. If unsure, go with the default, which is "Any". 2864 2865config PCI_GOBIOS 2866 bool "BIOS" 2867 2868config PCI_GOMMCONFIG 2869 bool "MMConfig" 2870 2871config PCI_GODIRECT 2872 bool "Direct" 2873 2874config PCI_GOOLPC 2875 bool "OLPC XO-1" 2876 depends on OLPC 2877 2878config PCI_GOANY 2879 bool "Any" 2880 2881endchoice 2882 2883config PCI_BIOS 2884 def_bool y 2885 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2886 2887# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2888config PCI_DIRECT 2889 def_bool y 2890 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2891 2892config PCI_MMCONFIG 2893 bool "Support mmconfig PCI config space access" if X86_64 2894 default y 2895 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2896 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2897 help 2898 Add support for accessing the PCI configuration space as a memory 2899 mapped area. It is the recommended method if the system supports 2900 this (it must have PCI Express and ACPI for it to be available). 2901 2902 In the unlikely case that enabling this configuration option causes 2903 problems, the mechanism can be switched off with the 'pci=nommconf' 2904 command line parameter. 2905 2906 Say N only if you are sure that your platform does not support this 2907 access method or you have problems caused by it. 2908 2909 Say Y otherwise. 2910 2911config PCI_OLPC 2912 def_bool y 2913 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2914 2915config PCI_XEN 2916 def_bool y 2917 depends on PCI && XEN 2918 2919config MMCONF_FAM10H 2920 def_bool y 2921 depends on X86_64 && PCI_MMCONFIG && ACPI 2922 2923config PCI_CNB20LE_QUIRK 2924 bool "Read PCI host bridge windows from the CNB20LE chipset" if EXPERT 2925 depends on X86_32 && PCI 2926 help 2927 Read the PCI windows out of the CNB20LE host bridge. This allows 2928 PCI hotplug to work on systems with the CNB20LE chipset which do 2929 not have ACPI. 2930 2931 The ServerWorks (later Broadcom) CNB20LE was a chipset designed 2932 most probably only for Pentium III. 2933 2934 To find out if you have such a chipset, search for a PCI device with 2935 1166:0009 PCI IDs, for example by executing 2936 lspci -nn | grep '1166:0009' 2937 The code is inactive if there is none. 2938 2939 There's no public spec for this chipset, and this functionality 2940 is known to be incomplete. 2941 2942 You should say N unless you know you need this. 2943 2944config ISA_BUS 2945 bool "ISA bus support on modern systems" if EXPERT 2946 help 2947 Expose ISA bus device drivers and options available for selection and 2948 configuration. Enable this option if your target machine has an ISA 2949 bus. ISA is an older system, displaced by PCI and newer bus 2950 architectures -- if your target machine is modern, it probably does 2951 not have an ISA bus. 2952 2953 If unsure, say N. 2954 2955# x86_64 have no ISA slots, but can have ISA-style DMA. 2956config ISA_DMA_API 2957 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2958 default y 2959 help 2960 Enables ISA-style DMA support for devices requiring such controllers. 2961 If unsure, say Y. 2962 2963if X86_32 2964 2965config ISA 2966 bool "ISA support" 2967 help 2968 Find out whether you have ISA slots on your motherboard. ISA is the 2969 name of a bus system, i.e. the way the CPU talks to the other stuff 2970 inside your box. Other bus systems are PCI, EISA, MicroChannel 2971 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2972 newer boards don't support it. If you have ISA, say Y, otherwise N. 2973 2974config SCx200 2975 tristate "NatSemi SCx200 support" 2976 help 2977 This provides basic support for National Semiconductor's 2978 (now AMD's) Geode processors. The driver probes for the 2979 PCI-IDs of several on-chip devices, so its a good dependency 2980 for other scx200_* drivers. 2981 2982 If compiled as a module, the driver is named scx200. 2983 2984config SCx200HR_TIMER 2985 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2986 depends on SCx200 2987 default y 2988 help 2989 This driver provides a clocksource built upon the on-chip 2990 27MHz high-resolution timer. Its also a workaround for 2991 NSC Geode SC-1100's buggy TSC, which loses time when the 2992 processor goes idle (as is done by the scheduler). The 2993 other workaround is idle=poll boot option. 2994 2995config OLPC 2996 bool "One Laptop Per Child support" 2997 depends on !X86_PAE 2998 select GPIOLIB 2999 select OF 3000 select OF_PROMTREE 3001 select IRQ_DOMAIN 3002 select OLPC_EC 3003 help 3004 Add support for detecting the unique features of the OLPC 3005 XO hardware. 3006 3007config OLPC_XO1_PM 3008 bool "OLPC XO-1 Power Management" 3009 depends on OLPC && MFD_CS5535=y && PM_SLEEP 3010 help 3011 Add support for poweroff and suspend of the OLPC XO-1 laptop. 3012 3013config OLPC_XO1_RTC 3014 bool "OLPC XO-1 Real Time Clock" 3015 depends on OLPC_XO1_PM && RTC_DRV_CMOS 3016 help 3017 Add support for the XO-1 real time clock, which can be used as a 3018 programmable wakeup source. 3019 3020config OLPC_XO1_SCI 3021 bool "OLPC XO-1 SCI extras" 3022 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 3023 depends on INPUT=y 3024 select POWER_SUPPLY 3025 help 3026 Add support for SCI-based features of the OLPC XO-1 laptop: 3027 - EC-driven system wakeups 3028 - Power button 3029 - Ebook switch 3030 - Lid switch 3031 - AC adapter status updates 3032 - Battery status updates 3033 3034config OLPC_XO15_SCI 3035 bool "OLPC XO-1.5 SCI extras" 3036 depends on OLPC && ACPI 3037 select POWER_SUPPLY 3038 help 3039 Add support for SCI-based features of the OLPC XO-1.5 laptop: 3040 - EC-driven system wakeups 3041 - AC adapter status updates 3042 - Battery status updates 3043 3044config GEODE_COMMON 3045 bool 3046 3047config ALIX 3048 bool "PCEngines ALIX System Support (LED setup)" 3049 select GPIOLIB 3050 select GEODE_COMMON 3051 help 3052 This option enables system support for the PCEngines ALIX. 3053 At present this just sets up LEDs for GPIO control on 3054 ALIX2/3/6 boards. However, other system specific setup should 3055 get added here. 3056 3057 Note: You must still enable the drivers for GPIO and LED support 3058 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 3059 3060 Note: You have to set alix.force=1 for boards with Award BIOS. 3061 3062config NET5501 3063 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3064 select GPIOLIB 3065 select GEODE_COMMON 3066 help 3067 This option enables system support for the Soekris Engineering net5501. 3068 3069config GEOS 3070 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3071 select GPIOLIB 3072 select GEODE_COMMON 3073 depends on DMI 3074 help 3075 This option enables system support for the Traverse Technologies GEOS. 3076 3077config TS5500 3078 bool "Technologic Systems TS-5500 platform support" 3079 depends on MELAN 3080 select CHECK_SIGNATURE 3081 select NEW_LEDS 3082 select LEDS_CLASS 3083 help 3084 This option enables system support for the Technologic Systems TS-5500. 3085 3086endif # X86_32 3087 3088config AMD_NB 3089 def_bool y 3090 depends on AMD_NODE 3091 3092config AMD_NODE 3093 def_bool y 3094 depends on CPU_SUP_AMD && PCI 3095 3096endmenu 3097 3098menu "Binary Emulations" 3099 3100config IA32_EMULATION 3101 bool "IA32 Emulation" 3102 depends on X86_64 3103 select ARCH_WANT_OLD_COMPAT_IPC 3104 select BINFMT_ELF 3105 select COMPAT_OLD_SIGACTION 3106 help 3107 Include code to run legacy 32-bit programs under a 3108 64-bit kernel. You should likely turn this on, unless you're 3109 100% sure that you don't have any 32-bit programs left. 3110 3111config IA32_EMULATION_DEFAULT_DISABLED 3112 bool "IA32 emulation disabled by default" 3113 default n 3114 depends on IA32_EMULATION 3115 help 3116 Make IA32 emulation disabled by default. This prevents loading 32-bit 3117 processes and access to 32-bit syscalls. If unsure, leave it to its 3118 default value. 3119 3120config X86_X32_ABI 3121 bool "x32 ABI for 64-bit mode" 3122 depends on X86_64 3123 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3124 # compressed debug sections to x86_x32 properly: 3125 # https://github.com/ClangBuiltLinux/linux/issues/514 3126 # https://github.com/ClangBuiltLinux/linux/issues/1141 3127 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3128 help 3129 Include code to run binaries for the x32 native 32-bit ABI 3130 for 64-bit processors. An x32 process gets access to the 3131 full 64-bit register file and wide data path while leaving 3132 pointers at 32 bits for smaller memory footprint. 3133 3134config COMPAT_32 3135 def_bool y 3136 depends on IA32_EMULATION || X86_32 3137 select HAVE_UID16 3138 select OLD_SIGSUSPEND3 3139 3140config COMPAT 3141 def_bool y 3142 depends on IA32_EMULATION || X86_X32_ABI 3143 3144config COMPAT_FOR_U64_ALIGNMENT 3145 def_bool y 3146 depends on COMPAT 3147 3148endmenu 3149 3150config HAVE_ATOMIC_IOMAP 3151 def_bool y 3152 depends on X86_32 3153 3154source "arch/x86/kvm/Kconfig" 3155 3156source "arch/x86/Kconfig.cpufeatures" 3157 3158source "arch/x86/Kconfig.assembler" 3159