1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_HAS_PTDUMP 30 select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 31 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 32 select ARCH_SUPPORTS_PER_VMA_LOCK 33 select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE 34 select HAVE_ARCH_SOFT_DIRTY 35 select MODULES_USE_ELF_RELA 36 select NEED_DMA_MAP_STATE 37 select SWIOTLB 38 select ARCH_HAS_ELFCORE_COMPAT 39 select ZONE_DMA32 40 select EXECMEM if DYNAMIC_FTRACE 41 select ACPI_MRRM if ACPI 42 43config FORCE_DYNAMIC_FTRACE 44 def_bool y 45 depends on X86_32 46 depends on FUNCTION_TRACER 47 select DYNAMIC_FTRACE 48 help 49 We keep the static function tracing (!DYNAMIC_FTRACE) around 50 in order to test the non static function tracing in the 51 generic code, as other architectures still use it. But we 52 only need to keep it around for x86_64. No need to keep it 53 for x86_32. For x86_32, force DYNAMIC_FTRACE. 54# 55# Arch settings 56# 57# ( Note that options that are marked 'if X86_64' could in principle be 58# ported to 32-bit as well. ) 59# 60config X86 61 def_bool y 62 # 63 # Note: keep this list sorted alphabetically 64 # 65 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 66 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 67 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 68 select ARCH_32BIT_OFF_T if X86_32 69 select ARCH_CLOCKSOURCE_INIT 70 select ARCH_CONFIGURES_CPU_MITIGATIONS 71 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 72 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 73 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 74 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 75 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 76 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 77 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 78 select ARCH_HAS_CPU_ATTACK_VECTORS if CPU_MITIGATIONS 79 select ARCH_HAS_CACHE_LINE_SIZE 80 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 81 select ARCH_HAS_CPU_FINALIZE_INIT 82 select ARCH_HAS_CPU_PASID if IOMMU_SVA 83 select ARCH_HAS_CURRENT_STACK_POINTER 84 select ARCH_HAS_DEBUG_VIRTUAL 85 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 86 select ARCH_HAS_DEVMEM_IS_ALLOWED 87 select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN 88 select ARCH_HAS_EARLY_DEBUG if KGDB 89 select ARCH_HAS_ELF_RANDOMIZE 90 select ARCH_HAS_EXECMEM_ROX if X86_64 && STRICT_MODULE_RWX 91 select ARCH_HAS_FAST_MULTIPLIER 92 select ARCH_HAS_FORTIFY_SOURCE 93 select ARCH_HAS_GCOV_PROFILE_ALL 94 select ARCH_HAS_KCOV if X86_64 95 select ARCH_HAS_KERNEL_FPU_SUPPORT 96 select ARCH_HAS_MEM_ENCRYPT 97 select ARCH_HAS_MEMBARRIER_SYNC_CORE 98 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 99 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 100 select ARCH_HAS_PMEM_API if X86_64 101 select ARCH_HAS_PREEMPT_LAZY 102 select ARCH_HAS_PTE_DEVMAP if X86_64 103 select ARCH_HAS_PTE_SPECIAL 104 select ARCH_HAS_HW_PTE_YOUNG 105 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 106 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 107 select ARCH_HAS_COPY_MC if X86_64 108 select ARCH_HAS_SET_MEMORY 109 select ARCH_HAS_SET_DIRECT_MAP 110 select ARCH_HAS_STRICT_KERNEL_RWX 111 select ARCH_HAS_STRICT_MODULE_RWX 112 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 113 select ARCH_HAS_SYSCALL_WRAPPER 114 select ARCH_HAS_UBSAN 115 select ARCH_HAS_DEBUG_WX 116 select ARCH_HAS_ZONE_DMA_SET if EXPERT 117 select ARCH_HAVE_NMI_SAFE_CMPXCHG 118 select ARCH_HAVE_EXTRA_ELF_NOTES 119 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 120 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 121 select ARCH_MIGHT_HAVE_PC_PARPORT 122 select ARCH_MIGHT_HAVE_PC_SERIO 123 select ARCH_STACKWALK 124 select ARCH_SUPPORTS_ACPI 125 select ARCH_SUPPORTS_ATOMIC_RMW 126 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 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_CLANG if X86_64 131 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 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_FTRACE_MCOUNT_RECORD 246 select HAVE_FUNCTION_GRAPH_FREGS if HAVE_FUNCTION_GRAPH_TRACER 247 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 248 select HAVE_FUNCTION_TRACER 249 select HAVE_GCC_PLUGINS 250 select HAVE_HW_BREAKPOINT 251 select HAVE_IOREMAP_PROT 252 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 253 select HAVE_IRQ_TIME_ACCOUNTING 254 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 255 select HAVE_KERNEL_BZIP2 256 select HAVE_KERNEL_GZIP 257 select HAVE_KERNEL_LZ4 258 select HAVE_KERNEL_LZMA 259 select HAVE_KERNEL_LZO 260 select HAVE_KERNEL_XZ 261 select HAVE_KERNEL_ZSTD 262 select HAVE_KPROBES 263 select HAVE_KPROBES_ON_FTRACE 264 select HAVE_FUNCTION_ERROR_INJECTION 265 select HAVE_KRETPROBES 266 select HAVE_RETHOOK 267 select HAVE_LIVEPATCH if X86_64 268 select HAVE_MIXED_BREAKPOINTS_REGS 269 select HAVE_MOD_ARCH_SPECIFIC 270 select HAVE_MOVE_PMD 271 select HAVE_MOVE_PUD 272 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 273 select HAVE_NMI 274 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 275 select HAVE_OBJTOOL if X86_64 276 select HAVE_OPTPROBES 277 select HAVE_PAGE_SIZE_4KB 278 select HAVE_PCSPKR_PLATFORM 279 select HAVE_PERF_EVENTS 280 select HAVE_PERF_EVENTS_NMI 281 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 282 select HAVE_PCI 283 select HAVE_PERF_REGS 284 select HAVE_PERF_USER_STACK_DUMP 285 select MMU_GATHER_RCU_TABLE_FREE 286 select MMU_GATHER_MERGE_VMAS 287 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 288 select HAVE_REGS_AND_STACK_ACCESS_API 289 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 290 select HAVE_FUNCTION_ARG_ACCESS_API 291 select HAVE_SETUP_PER_CPU_AREA 292 select HAVE_SOFTIRQ_ON_OWN_STACK 293 select HAVE_STACKPROTECTOR 294 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 295 select HAVE_STATIC_CALL 296 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 297 select HAVE_PREEMPT_DYNAMIC_CALL 298 select HAVE_RSEQ 299 select HAVE_RUST if X86_64 300 select HAVE_SYSCALL_TRACEPOINTS 301 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 302 select HAVE_UNSTABLE_SCHED_CLOCK 303 select HAVE_USER_RETURN_NOTIFIER 304 select HAVE_GENERIC_VDSO 305 select VDSO_GETRANDOM if X86_64 306 select HOTPLUG_PARALLEL if SMP && X86_64 307 select HOTPLUG_SMT if SMP 308 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 309 select IRQ_FORCED_THREADING 310 select LOCK_MM_AND_FIND_VMA 311 select NEED_PER_CPU_EMBED_FIRST_CHUNK 312 select NEED_PER_CPU_PAGE_FIRST_CHUNK 313 select NEED_SG_DMA_LENGTH 314 select NUMA_MEMBLKS if NUMA 315 select PCI_DOMAINS if PCI 316 select PCI_LOCKLESS_CONFIG if PCI 317 select PERF_EVENTS 318 select RTC_LIB 319 select RTC_MC146818_LIB 320 select SPARSE_IRQ 321 select SYSCTL_EXCEPTION_TRACE 322 select THREAD_INFO_IN_TASK 323 select TRACE_IRQFLAGS_SUPPORT 324 select TRACE_IRQFLAGS_NMI_SUPPORT 325 select USER_STACKTRACE_SUPPORT 326 select HAVE_ARCH_KCSAN if X86_64 327 select PROC_PID_ARCH_STATUS if PROC_FS 328 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 329 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 330 select FUNCTION_ALIGNMENT_4B 331 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 332 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 333 select ARCH_SUPPORTS_PT_RECLAIM if X86_64 334 335config INSTRUCTION_DECODER 336 def_bool y 337 depends on KPROBES || PERF_EVENTS || UPROBES 338 339config OUTPUT_FORMAT 340 string 341 default "elf32-i386" if X86_32 342 default "elf64-x86-64" if X86_64 343 344config LOCKDEP_SUPPORT 345 def_bool y 346 347config STACKTRACE_SUPPORT 348 def_bool y 349 350config MMU 351 def_bool y 352 353config ARCH_MMAP_RND_BITS_MIN 354 default 28 if 64BIT 355 default 8 356 357config ARCH_MMAP_RND_BITS_MAX 358 default 32 if 64BIT 359 default 16 360 361config ARCH_MMAP_RND_COMPAT_BITS_MIN 362 default 8 363 364config ARCH_MMAP_RND_COMPAT_BITS_MAX 365 default 16 366 367config SBUS 368 bool 369 370config GENERIC_ISA_DMA 371 def_bool y 372 depends on ISA_DMA_API 373 374config GENERIC_CSUM 375 bool 376 default y if KMSAN || KASAN 377 378config GENERIC_BUG 379 def_bool y 380 depends on BUG 381 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 382 383config GENERIC_BUG_RELATIVE_POINTERS 384 bool 385 386config ARCH_MAY_HAVE_PC_FDC 387 def_bool y 388 depends on ISA_DMA_API 389 390config GENERIC_CALIBRATE_DELAY 391 def_bool y 392 393config ARCH_HAS_CPU_RELAX 394 def_bool y 395 396config ARCH_HIBERNATION_POSSIBLE 397 def_bool y 398 399config ARCH_SUSPEND_POSSIBLE 400 def_bool y 401 402config AUDIT_ARCH 403 def_bool y if X86_64 404 405config KASAN_SHADOW_OFFSET 406 hex 407 depends on KASAN 408 default 0xdffffc0000000000 409 410config HAVE_INTEL_TXT 411 def_bool y 412 depends on INTEL_IOMMU && ACPI 413 414config X86_64_SMP 415 def_bool y 416 depends on X86_64 && SMP 417 418config ARCH_SUPPORTS_UPROBES 419 def_bool y 420 421config FIX_EARLYCON_MEM 422 def_bool y 423 424config DYNAMIC_PHYSICAL_MASK 425 bool 426 427config PGTABLE_LEVELS 428 int 429 default 5 if X86_64 430 default 3 if X86_PAE 431 default 2 432 433menu "Processor type and features" 434 435config SMP 436 bool "Symmetric multi-processing support" 437 help 438 This enables support for systems with more than one CPU. If you have 439 a system with only one CPU, say N. If you have a system with more 440 than one CPU, say Y. 441 442 If you say N here, the kernel will run on uni- and multiprocessor 443 machines, but will use only one CPU of a multiprocessor machine. If 444 you say Y here, the kernel will run on many, but not all, 445 uniprocessor machines. On a uniprocessor machine, the kernel 446 will run faster if you say N here. 447 448 Note that if you say Y here and choose architecture "586" or 449 "Pentium" under "Processor family", the kernel will not work on 486 450 architectures. Similarly, multiprocessor kernels for the "PPro" 451 architecture may not work on all Pentium based boards. 452 453 People using multiprocessor machines who say Y here should also say 454 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 455 Management" code will be disabled if you say Y here. 456 457 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 458 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 459 <http://www.tldp.org/docs.html#howto>. 460 461 If you don't know what to do here, say N. 462 463config X86_X2APIC 464 bool "x2APIC interrupt controller architecture support" 465 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 466 default y 467 help 468 x2APIC is an interrupt controller architecture, a component of which 469 (the local APIC) is present in the CPU. It allows faster access to 470 the local APIC and supports a larger number of CPUs in the system 471 than the predecessors. 472 473 x2APIC was introduced in Intel CPUs around 2008 and in AMD EPYC CPUs 474 in 2019, but it can be disabled by the BIOS. It is also frequently 475 emulated in virtual machines, even when the host CPU does not support 476 it. Support in the CPU can be checked by executing 477 grep x2apic /proc/cpuinfo 478 479 If this configuration option is disabled, the kernel will boot with 480 very reduced functionality and performance on some platforms that 481 have x2APIC enabled. On the other hand, on hardware that does not 482 support x2APIC, a kernel with this option enabled will just fallback 483 to older APIC implementations. 484 485 If in doubt, say Y. 486 487config X86_POSTED_MSI 488 bool "Enable MSI and MSI-x delivery by posted interrupts" 489 depends on X86_64 && IRQ_REMAP 490 help 491 This enables MSIs that are under interrupt remapping to be delivered as 492 posted interrupts to the host kernel. Interrupt throughput can 493 potentially be improved by coalescing CPU notifications during high 494 frequency bursts. 495 496 If you don't know what to do here, say N. 497 498config X86_MPPARSE 499 bool "Enable MPS table" if ACPI 500 default y 501 depends on X86_LOCAL_APIC 502 help 503 For old smp systems that do not have proper acpi support. Newer systems 504 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 505 506config X86_CPU_RESCTRL 507 bool "x86 CPU resource control support" 508 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 509 depends on MISC_FILESYSTEMS 510 select ARCH_HAS_CPU_RESCTRL 511 select RESCTRL_FS 512 select RESCTRL_FS_PSEUDO_LOCK 513 help 514 Enable x86 CPU resource control support. 515 516 Provide support for the allocation and monitoring of system resources 517 usage by the CPU. 518 519 Intel calls this Intel Resource Director Technology 520 (Intel(R) RDT). More information about RDT can be found in the 521 Intel x86 Architecture Software Developer Manual. 522 523 AMD calls this AMD Platform Quality of Service (AMD QoS). 524 More information about AMD QoS can be found in the AMD64 Technology 525 Platform Quality of Service Extensions manual. 526 527 Say N if unsure. 528 529config X86_FRED 530 bool "Flexible Return and Event Delivery" 531 depends on X86_64 532 help 533 When enabled, try to use Flexible Return and Event Delivery 534 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 535 ring transitions and exception/interrupt handling if the 536 system supports it. 537 538config X86_EXTENDED_PLATFORM 539 bool "Support for extended (non-PC) x86 platforms" 540 default y 541 help 542 If you disable this option then the kernel will only support 543 standard PC platforms. (which covers the vast majority of 544 systems out there.) 545 546 If you enable this option then you'll be able to select support 547 for the following non-PC x86 platforms, depending on the value of 548 CONFIG_64BIT. 549 550 32-bit platforms (CONFIG_64BIT=n): 551 Goldfish (mostly Android emulator) 552 Intel CE media processor (CE4100) SoC 553 Intel Quark 554 RDC R-321x SoC 555 556 64-bit platforms (CONFIG_64BIT=y): 557 Numascale NumaChip 558 ScaleMP vSMP 559 SGI Ultraviolet 560 Merrifield/Moorefield MID devices 561 Goldfish (mostly Android emulator) 562 563 If you have one of these systems, or if you want to build a 564 generic distribution kernel, say Y here - otherwise say N. 565 566# This is an alphabetically sorted list of 64 bit extended platforms 567# Please maintain the alphabetic order if and when there are additions 568config X86_NUMACHIP 569 bool "Numascale NumaChip" 570 depends on X86_64 571 depends on X86_EXTENDED_PLATFORM 572 depends on NUMA 573 depends on SMP 574 depends on X86_X2APIC 575 depends on PCI_MMCONFIG 576 help 577 Adds support for Numascale NumaChip large-SMP systems. Needed to 578 enable more than ~168 cores. 579 If you don't have one of these, you should say N here. 580 581config X86_VSMP 582 bool "ScaleMP vSMP" 583 select HYPERVISOR_GUEST 584 select PARAVIRT 585 depends on X86_64 && PCI 586 depends on X86_EXTENDED_PLATFORM 587 depends on SMP 588 help 589 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 590 supposed to run on these EM64T-based machines. Only choose this option 591 if you have one of these machines. 592 593config X86_UV 594 bool "SGI Ultraviolet" 595 depends on X86_64 596 depends on X86_EXTENDED_PLATFORM 597 depends on NUMA 598 depends on EFI 599 depends on KEXEC_CORE 600 depends on X86_X2APIC 601 depends on PCI 602 help 603 This option is needed in order to support SGI Ultraviolet systems. 604 If you don't have one of these, you should say N here. 605 606config X86_INTEL_MID 607 bool "Intel Z34xx/Z35xx MID platform support" 608 depends on X86_EXTENDED_PLATFORM 609 depends on X86_PLATFORM_DEVICES 610 depends on PCI 611 depends on X86_64 || (EXPERT && PCI_GOANY) 612 depends on X86_IO_APIC 613 select I2C 614 select DW_APB_TIMER 615 select INTEL_SCU_PCI 616 help 617 Select to build a kernel capable of supporting 64-bit Intel MID 618 (Mobile Internet Device) platform systems which do not have 619 the PCI legacy interfaces. 620 621 The only supported devices are the 22nm Merrified (Z34xx) 622 and Moorefield (Z35xx) SoC used in the Intel Edison board and 623 a small number of Android devices such as the Asus Zenfone 2, 624 Asus FonePad 8 and Dell Venue 7. 625 626 If you are building for a PC class system or non-MID tablet 627 SoCs like Bay Trail (Z36xx/Z37xx), say N here. 628 629 Intel MID platforms are based on an Intel processor and chipset which 630 consume less power than most of the x86 derivatives. 631 632config X86_GOLDFISH 633 bool "Goldfish (Virtual Platform)" 634 depends on X86_EXTENDED_PLATFORM 635 help 636 Enable support for the Goldfish virtual platform used primarily 637 for Android development. Unless you are building for the Android 638 Goldfish emulator say N here. 639 640# Following is an alphabetically sorted list of 32 bit extended platforms 641# Please maintain the alphabetic order if and when there are additions 642 643config X86_INTEL_CE 644 bool "CE4100 TV platform" 645 depends on PCI 646 depends on PCI_GODIRECT 647 depends on X86_IO_APIC 648 depends on X86_32 649 depends on X86_EXTENDED_PLATFORM 650 select X86_REBOOTFIXUPS 651 select OF 652 select OF_EARLY_FLATTREE 653 help 654 Select for the Intel CE media processor (CE4100) SOC. 655 This option compiles in support for the CE4100 SOC for settop 656 boxes and media devices. 657 658config X86_INTEL_QUARK 659 bool "Intel Quark platform support" 660 depends on X86_32 661 depends on X86_EXTENDED_PLATFORM 662 depends on X86_PLATFORM_DEVICES 663 depends on X86_TSC 664 depends on PCI 665 depends on PCI_GOANY 666 depends on X86_IO_APIC 667 select IOSF_MBI 668 select INTEL_IMR 669 select COMMON_CLK 670 help 671 Select to include support for Quark X1000 SoC. 672 Say Y here if you have a Quark based system such as the Arduino 673 compatible Intel Galileo. 674 675config X86_RDC321X 676 bool "RDC R-321x SoC" 677 depends on X86_32 678 depends on X86_EXTENDED_PLATFORM 679 select M486 680 select X86_REBOOTFIXUPS 681 help 682 This option is needed for RDC R-321x system-on-chip, also known 683 as R-8610-(G). 684 If you don't have one of these chips, you should say N here. 685 686config X86_INTEL_LPSS 687 bool "Intel Low Power Subsystem Support" 688 depends on X86 && ACPI && PCI 689 select COMMON_CLK 690 select PINCTRL 691 select IOSF_MBI 692 help 693 Select to build support for Intel Low Power Subsystem such as 694 found on Intel Lynxpoint PCH. Selecting this option enables 695 things like clock tree (common clock framework) and pincontrol 696 which are needed by the LPSS peripheral drivers. 697 698config X86_AMD_PLATFORM_DEVICE 699 bool "AMD ACPI2Platform devices support" 700 depends on ACPI 701 select COMMON_CLK 702 select PINCTRL 703 help 704 Select to interpret AMD specific ACPI device to platform device 705 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 706 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 707 implemented under PINCTRL subsystem. 708 709config IOSF_MBI 710 tristate "Intel SoC IOSF Sideband support for SoC platforms" 711 depends on PCI 712 help 713 This option enables sideband register access support for Intel SoC 714 platforms. On these platforms the IOSF sideband is used in lieu of 715 MSR's for some register accesses, mostly but not limited to thermal 716 and power. Drivers may query the availability of this device to 717 determine if they need the sideband in order to work on these 718 platforms. The sideband is available on the following SoC products. 719 This list is not meant to be exclusive. 720 - BayTrail 721 - Braswell 722 - Quark 723 724 You should say Y if you are running a kernel on one of these SoC's. 725 726config IOSF_MBI_DEBUG 727 bool "Enable IOSF sideband access through debugfs" 728 depends on IOSF_MBI && DEBUG_FS 729 help 730 Select this option to expose the IOSF sideband access registers (MCR, 731 MDR, MCRX) through debugfs to write and read register information from 732 different units on the SoC. This is most useful for obtaining device 733 state information for debug and analysis. As this is a general access 734 mechanism, users of this option would have specific knowledge of the 735 device they want to access. 736 737 If you don't require the option or are in doubt, say N. 738 739config X86_SUPPORTS_MEMORY_FAILURE 740 def_bool y 741 # MCE code calls memory_failure(): 742 depends on X86_MCE 743 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 744 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 745 depends on X86_64 || !SPARSEMEM 746 select ARCH_SUPPORTS_MEMORY_FAILURE 747 748config X86_32_IRIS 749 tristate "Eurobraille/Iris poweroff module" 750 depends on X86_32 751 help 752 The Iris machines from EuroBraille do not have APM or ACPI support 753 to shut themselves down properly. A special I/O sequence is 754 needed to do so, which is what this module does at 755 kernel shutdown. 756 757 This is only for Iris machines from EuroBraille. 758 759 If unused, say N. 760 761config SCHED_OMIT_FRAME_POINTER 762 def_bool y 763 prompt "Single-depth WCHAN output" 764 depends on X86 765 help 766 Calculate simpler /proc/<PID>/wchan values. If this option 767 is disabled then wchan values will recurse back to the 768 caller function. This provides more accurate wchan values, 769 at the expense of slightly more scheduling overhead. 770 771 If in doubt, say "Y". 772 773menuconfig HYPERVISOR_GUEST 774 bool "Linux guest support" 775 help 776 Say Y here to enable options for running Linux under various hyper- 777 visors. This option enables basic hypervisor detection and platform 778 setup. 779 780 If you say N, all options in this submenu will be skipped and 781 disabled, and Linux guest support won't be built in. 782 783if HYPERVISOR_GUEST 784 785config PARAVIRT 786 bool "Enable paravirtualization code" 787 depends on HAVE_STATIC_CALL 788 help 789 This changes the kernel so it can modify itself when it is run 790 under a hypervisor, potentially improving performance significantly 791 over full virtualization. However, when run without a hypervisor 792 the kernel is theoretically slower and slightly larger. 793 794config PARAVIRT_XXL 795 bool 796 depends on X86_64 797 798config PARAVIRT_DEBUG 799 bool "paravirt-ops debugging" 800 depends on PARAVIRT && DEBUG_KERNEL 801 help 802 Enable to debug paravirt_ops internals. Specifically, BUG if 803 a paravirt_op is missing when it is called. 804 805config PARAVIRT_SPINLOCKS 806 bool "Paravirtualization layer for spinlocks" 807 depends on PARAVIRT && SMP 808 help 809 Paravirtualized spinlocks allow a pvops backend to replace the 810 spinlock implementation with something virtualization-friendly 811 (for example, block the virtual CPU rather than spinning). 812 813 It has a minimal impact on native kernels and gives a nice performance 814 benefit on paravirtualized KVM / Xen kernels. 815 816 If you are unsure how to answer this question, answer Y. 817 818config X86_HV_CALLBACK_VECTOR 819 def_bool n 820 821source "arch/x86/xen/Kconfig" 822 823config KVM_GUEST 824 bool "KVM Guest support (including kvmclock)" 825 depends on PARAVIRT 826 select PARAVIRT_CLOCK 827 select ARCH_CPUIDLE_HALTPOLL 828 select X86_HV_CALLBACK_VECTOR 829 default y 830 help 831 This option enables various optimizations for running under the KVM 832 hypervisor. It includes a paravirtualized clock, so that instead 833 of relying on a PIT (or probably other) emulation by the 834 underlying device model, the host provides the guest with 835 timing infrastructure such as time of day, and system time 836 837config ARCH_CPUIDLE_HALTPOLL 838 def_bool n 839 prompt "Disable host haltpoll when loading haltpoll driver" 840 help 841 If virtualized under KVM, disable host haltpoll. 842 843config PVH 844 bool "Support for running PVH guests" 845 help 846 This option enables the PVH entry point for guest virtual machines 847 as specified in the x86/HVM direct boot ABI. 848 849config PARAVIRT_TIME_ACCOUNTING 850 bool "Paravirtual steal time accounting" 851 depends on PARAVIRT 852 help 853 Select this option to enable fine granularity task steal time 854 accounting. Time spent executing other tasks in parallel with 855 the current vCPU is discounted from the vCPU power. To account for 856 that, there can be a small performance impact. 857 858 If in doubt, say N here. 859 860config PARAVIRT_CLOCK 861 bool 862 863config JAILHOUSE_GUEST 864 bool "Jailhouse non-root cell support" 865 depends on X86_64 && PCI 866 select X86_PM_TIMER 867 help 868 This option allows to run Linux as guest in a Jailhouse non-root 869 cell. You can leave this option disabled if you only want to start 870 Jailhouse and run Linux afterwards in the root cell. 871 872config ACRN_GUEST 873 bool "ACRN Guest support" 874 depends on X86_64 875 select X86_HV_CALLBACK_VECTOR 876 help 877 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 878 a flexible, lightweight reference open-source hypervisor, built with 879 real-time and safety-criticality in mind. It is built for embedded 880 IOT with small footprint and real-time features. More details can be 881 found in https://projectacrn.org/. 882 883config INTEL_TDX_GUEST 884 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 885 depends on X86_64 && CPU_SUP_INTEL 886 depends on X86_X2APIC 887 depends on EFI_STUB 888 depends on PARAVIRT 889 select ARCH_HAS_CC_PLATFORM 890 select X86_MEM_ENCRYPT 891 select X86_MCE 892 select UNACCEPTED_MEMORY 893 help 894 Support running as a guest under Intel TDX. Without this support, 895 the guest kernel can not boot or run under TDX. 896 TDX includes memory encryption and integrity capabilities 897 which protect the confidentiality and integrity of guest 898 memory contents and CPU state. TDX guests are protected from 899 some attacks from the VMM. 900 901endif # HYPERVISOR_GUEST 902 903source "arch/x86/Kconfig.cpu" 904 905config HPET_TIMER 906 def_bool X86_64 907 prompt "HPET Timer Support" if X86_32 908 help 909 Use the IA-PC HPET (High Precision Event Timer) to manage 910 time in preference to the PIT and RTC, if a HPET is 911 present. 912 HPET is the next generation timer replacing legacy 8254s. 913 The HPET provides a stable time base on SMP 914 systems, unlike the TSC, but it is more expensive to access, 915 as it is off-chip. The interface used is documented 916 in the HPET spec, revision 1. 917 918 You can safely choose Y here. However, HPET will only be 919 activated if the platform and the BIOS support this feature. 920 Otherwise the 8254 will be used for timing services. 921 922 Choose N to continue using the legacy 8254 timer. 923 924config HPET_EMULATE_RTC 925 def_bool y 926 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 927 928# Mark as expert because too many people got it wrong. 929# The code disables itself when not needed. 930config DMI 931 default y 932 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 933 bool "Enable DMI scanning" if EXPERT 934 help 935 Enabled scanning of DMI to identify machine quirks. Say Y 936 here unless you have verified that your setup is not 937 affected by entries in the DMI blacklist. Required by PNP 938 BIOS code. 939 940config GART_IOMMU 941 bool "Old AMD GART IOMMU support" 942 select IOMMU_HELPER 943 select SWIOTLB 944 depends on X86_64 && PCI && AMD_NB 945 help 946 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 947 GART based hardware IOMMUs. 948 949 The GART supports full DMA access for devices with 32-bit access 950 limitations, on systems with more than 3 GB. This is usually needed 951 for USB, sound, many IDE/SATA chipsets and some other devices. 952 953 Newer systems typically have a modern AMD IOMMU, supported via 954 the CONFIG_AMD_IOMMU=y config option. 955 956 In normal configurations this driver is only active when needed: 957 there's more than 3 GB of memory and the system contains a 958 32-bit limited device. 959 960 If unsure, say Y. 961 962config BOOT_VESA_SUPPORT 963 bool 964 help 965 If true, at least one selected framebuffer driver can take advantage 966 of VESA video modes set at an early boot stage via the vga= parameter. 967 968config MAXSMP 969 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 970 depends on X86_64 && SMP && DEBUG_KERNEL 971 select CPUMASK_OFFSTACK 972 help 973 Enable maximum number of CPUS and NUMA Nodes for this architecture. 974 If unsure, say N. 975 976# 977# The maximum number of CPUs supported: 978# 979# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 980# and which can be configured interactively in the 981# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 982# 983# The ranges are different on 32-bit and 64-bit kernels, depending on 984# hardware capabilities and scalability features of the kernel. 985# 986# ( If MAXSMP is enabled we just use the highest possible value and disable 987# interactive configuration. ) 988# 989 990config NR_CPUS_RANGE_BEGIN 991 int 992 default NR_CPUS_RANGE_END if MAXSMP 993 default 1 if !SMP 994 default 2 995 996config NR_CPUS_RANGE_END 997 int 998 depends on X86_32 999 default 8 if SMP 1000 default 1 if !SMP 1001 1002config NR_CPUS_RANGE_END 1003 int 1004 depends on X86_64 1005 default 8192 if SMP && CPUMASK_OFFSTACK 1006 default 512 if SMP && !CPUMASK_OFFSTACK 1007 default 1 if !SMP 1008 1009config NR_CPUS_DEFAULT 1010 int 1011 depends on X86_32 1012 default 8 if SMP 1013 default 1 if !SMP 1014 1015config NR_CPUS_DEFAULT 1016 int 1017 depends on X86_64 1018 default 8192 if MAXSMP 1019 default 64 if SMP 1020 default 1 if !SMP 1021 1022config NR_CPUS 1023 int "Maximum number of CPUs" if SMP && !MAXSMP 1024 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1025 default NR_CPUS_DEFAULT 1026 help 1027 This allows you to specify the maximum number of CPUs which this 1028 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1029 supported value is 8192, otherwise the maximum value is 512. The 1030 minimum value which makes sense is 2. 1031 1032 This is purely to save memory: each supported CPU adds about 8KB 1033 to the kernel image. 1034 1035config SCHED_CLUSTER 1036 bool "Cluster scheduler support" 1037 depends on SMP 1038 default y 1039 help 1040 Cluster scheduler support improves the CPU scheduler's decision 1041 making when dealing with machines that have clusters of CPUs. 1042 Cluster usually means a couple of CPUs which are placed closely 1043 by sharing mid-level caches, last-level cache tags or internal 1044 busses. 1045 1046config SCHED_SMT 1047 def_bool y if SMP 1048 1049config SCHED_MC 1050 def_bool y 1051 prompt "Multi-core scheduler support" 1052 depends on SMP 1053 help 1054 Multi-core scheduler support improves the CPU scheduler's decision 1055 making when dealing with multi-core CPU chips at a cost of slightly 1056 increased overhead in some places. If unsure say N here. 1057 1058config SCHED_MC_PRIO 1059 bool "CPU core priorities scheduler support" 1060 depends on SCHED_MC 1061 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1062 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1063 select CPU_FREQ 1064 default y 1065 help 1066 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1067 core ordering determined at manufacturing time, which allows 1068 certain cores to reach higher turbo frequencies (when running 1069 single threaded workloads) than others. 1070 1071 Enabling this kernel feature teaches the scheduler about 1072 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1073 scheduler's CPU selection logic accordingly, so that higher 1074 overall system performance can be achieved. 1075 1076 This feature will have no effect on CPUs without this feature. 1077 1078 If unsure say Y here. 1079 1080config UP_LATE_INIT 1081 def_bool y 1082 depends on !SMP && X86_LOCAL_APIC 1083 1084config X86_UP_APIC 1085 bool "Local APIC support on uniprocessors" if !PCI_MSI 1086 default PCI_MSI 1087 depends on X86_32 && !SMP 1088 help 1089 A local APIC (Advanced Programmable Interrupt Controller) is an 1090 integrated interrupt controller in the CPU. If you have a single-CPU 1091 system which has a processor with a local APIC, you can say Y here to 1092 enable and use it. If you say Y here even though your machine doesn't 1093 have a local APIC, then the kernel will still run with no slowdown at 1094 all. The local APIC supports CPU-generated self-interrupts (timer, 1095 performance counters), and the NMI watchdog which detects hard 1096 lockups. 1097 1098config X86_UP_IOAPIC 1099 bool "IO-APIC support on uniprocessors" 1100 depends on X86_UP_APIC 1101 help 1102 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1103 SMP-capable replacement for PC-style interrupt controllers. Most 1104 SMP systems and many recent uniprocessor systems have one. 1105 1106 If you have a single-CPU system with an IO-APIC, you can say Y here 1107 to use it. If you say Y here even though your machine doesn't have 1108 an IO-APIC, then the kernel will still run with no slowdown at all. 1109 1110config X86_LOCAL_APIC 1111 def_bool y 1112 depends on X86_64 || SMP || X86_UP_APIC || PCI_MSI 1113 select IRQ_DOMAIN_HIERARCHY 1114 1115config ACPI_MADT_WAKEUP 1116 def_bool y 1117 depends on X86_64 1118 depends on ACPI 1119 depends on SMP 1120 depends on X86_LOCAL_APIC 1121 1122config X86_IO_APIC 1123 def_bool y 1124 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1125 1126config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1127 bool "Reroute for broken boot IRQs" 1128 depends on X86_IO_APIC 1129 help 1130 This option enables a workaround that fixes a source of 1131 spurious interrupts. This is recommended when threaded 1132 interrupt handling is used on systems where the generation of 1133 superfluous "boot interrupts" cannot be disabled. 1134 1135 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1136 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1137 kernel does during interrupt handling). On chipsets where this 1138 boot IRQ generation cannot be disabled, this workaround keeps 1139 the original IRQ line masked so that only the equivalent "boot 1140 IRQ" is delivered to the CPUs. The workaround also tells the 1141 kernel to set up the IRQ handler on the boot IRQ line. In this 1142 way only one interrupt is delivered to the kernel. Otherwise 1143 the spurious second interrupt may cause the kernel to bring 1144 down (vital) interrupt lines. 1145 1146 Only affects "broken" chipsets. Interrupt sharing may be 1147 increased on these systems. 1148 1149config X86_MCE 1150 bool "Machine Check / overheating reporting" 1151 select GENERIC_ALLOCATOR 1152 default y 1153 help 1154 Machine Check support allows the processor to notify the 1155 kernel if it detects a problem (e.g. overheating, data corruption). 1156 The action the kernel takes depends on the severity of the problem, 1157 ranging from warning messages to halting the machine. 1158 1159config X86_MCELOG_LEGACY 1160 bool "Support for deprecated /dev/mcelog character device" 1161 depends on X86_MCE 1162 help 1163 Enable support for /dev/mcelog which is needed by the old mcelog 1164 userspace logging daemon. Consider switching to the new generation 1165 rasdaemon solution. 1166 1167config X86_MCE_INTEL 1168 def_bool y 1169 prompt "Intel MCE features" 1170 depends on X86_MCE && X86_LOCAL_APIC 1171 help 1172 Additional support for intel specific MCE features such as 1173 the thermal monitor. 1174 1175config X86_MCE_AMD 1176 def_bool y 1177 prompt "AMD MCE features" 1178 depends on X86_MCE && X86_LOCAL_APIC 1179 help 1180 Additional support for AMD specific MCE features such as 1181 the DRAM Error Threshold. 1182 1183config X86_ANCIENT_MCE 1184 bool "Support for old Pentium 5 / WinChip machine checks" 1185 depends on X86_32 && X86_MCE 1186 help 1187 Include support for machine check handling on old Pentium 5 or WinChip 1188 systems. These typically need to be enabled explicitly on the command 1189 line. 1190 1191config X86_MCE_THRESHOLD 1192 depends on X86_MCE_AMD || X86_MCE_INTEL 1193 def_bool y 1194 1195config X86_MCE_INJECT 1196 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1197 tristate "Machine check injector support" 1198 help 1199 Provide support for injecting machine checks for testing purposes. 1200 If you don't know what a machine check is and you don't do kernel 1201 QA it is safe to say n. 1202 1203source "arch/x86/events/Kconfig" 1204 1205config X86_LEGACY_VM86 1206 bool "Legacy VM86 support" 1207 depends on X86_32 1208 help 1209 This option allows user programs to put the CPU into V8086 1210 mode, which is an 80286-era approximation of 16-bit real mode. 1211 1212 Some very old versions of X and/or vbetool require this option 1213 for user mode setting. Similarly, DOSEMU will use it if 1214 available to accelerate real mode DOS programs. However, any 1215 recent version of DOSEMU, X, or vbetool should be fully 1216 functional even without kernel VM86 support, as they will all 1217 fall back to software emulation. Nevertheless, if you are using 1218 a 16-bit DOS program where 16-bit performance matters, vm86 1219 mode might be faster than emulation and you might want to 1220 enable this option. 1221 1222 Note that any app that works on a 64-bit kernel is unlikely to 1223 need this option, as 64-bit kernels don't, and can't, support 1224 V8086 mode. This option is also unrelated to 16-bit protected 1225 mode and is not needed to run most 16-bit programs under Wine. 1226 1227 Enabling this option increases the complexity of the kernel 1228 and slows down exception handling a tiny bit. 1229 1230 If unsure, say N here. 1231 1232config VM86 1233 bool 1234 default X86_LEGACY_VM86 1235 1236config X86_16BIT 1237 bool "Enable support for 16-bit segments" if EXPERT 1238 default y 1239 depends on MODIFY_LDT_SYSCALL 1240 help 1241 This option is required by programs like Wine to run 16-bit 1242 protected mode legacy code on x86 processors. Disabling 1243 this option saves about 300 bytes on i386, or around 6K text 1244 plus 16K runtime memory on x86-64, 1245 1246config X86_ESPFIX32 1247 def_bool y 1248 depends on X86_16BIT && X86_32 1249 1250config X86_ESPFIX64 1251 def_bool y 1252 depends on X86_16BIT && X86_64 1253 1254config X86_VSYSCALL_EMULATION 1255 bool "Enable vsyscall emulation" if EXPERT 1256 default y 1257 depends on X86_64 1258 help 1259 This enables emulation of the legacy vsyscall page. Disabling 1260 it is roughly equivalent to booting with vsyscall=none, except 1261 that it will also disable the helpful warning if a program 1262 tries to use a vsyscall. With this option set to N, offending 1263 programs will just segfault, citing addresses of the form 1264 0xffffffffff600?00. 1265 1266 This option is required by many programs built before 2013, and 1267 care should be used even with newer programs if set to N. 1268 1269 Disabling this option saves about 7K of kernel size and 1270 possibly 4K of additional runtime pagetable memory. 1271 1272config X86_IOPL_IOPERM 1273 bool "IOPERM and IOPL Emulation" 1274 default y 1275 help 1276 This enables the ioperm() and iopl() syscalls which are necessary 1277 for legacy applications. 1278 1279 Legacy IOPL support is an overbroad mechanism which allows user 1280 space aside of accessing all 65536 I/O ports also to disable 1281 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1282 capabilities and permission from potentially active security 1283 modules. 1284 1285 The emulation restricts the functionality of the syscall to 1286 only allowing the full range I/O port access, but prevents the 1287 ability to disable interrupts from user space which would be 1288 granted if the hardware IOPL mechanism would be used. 1289 1290config TOSHIBA 1291 tristate "Toshiba Laptop support" 1292 depends on X86_32 1293 help 1294 This adds a driver to safely access the System Management Mode of 1295 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1296 not work on models with a Phoenix BIOS. The System Management Mode 1297 is used to set the BIOS and power saving options on Toshiba portables. 1298 1299 For information on utilities to make use of this driver see the 1300 Toshiba Linux utilities web site at: 1301 <http://www.buzzard.org.uk/toshiba/>. 1302 1303 Say Y if you intend to run this kernel on a Toshiba portable. 1304 Say N otherwise. 1305 1306config X86_REBOOTFIXUPS 1307 bool "Enable X86 board specific fixups for reboot" 1308 depends on X86_32 1309 help 1310 This enables chipset and/or board specific fixups to be done 1311 in order to get reboot to work correctly. This is only needed on 1312 some combinations of hardware and BIOS. The symptom, for which 1313 this config is intended, is when reboot ends with a stalled/hung 1314 system. 1315 1316 Currently, the only fixup is for the Geode machines using 1317 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1318 1319 Say Y if you want to enable the fixup. Currently, it's safe to 1320 enable this option even if you don't need it. 1321 Say N otherwise. 1322 1323config MICROCODE 1324 def_bool y 1325 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1326 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD 1327 1328config MICROCODE_INITRD32 1329 def_bool y 1330 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1331 1332config MICROCODE_LATE_LOADING 1333 bool "Late microcode loading (DANGEROUS)" 1334 default n 1335 depends on MICROCODE && SMP 1336 help 1337 Loading microcode late, when the system is up and executing instructions 1338 is a tricky business and should be avoided if possible. Just the sequence 1339 of synchronizing all cores and SMT threads is one fragile dance which does 1340 not guarantee that cores might not softlock after the loading. Therefore, 1341 use this at your own risk. Late loading taints the kernel unless the 1342 microcode header indicates that it is safe for late loading via the 1343 minimal revision check. This minimal revision check can be enforced on 1344 the kernel command line with "microcode.minrev=Y". 1345 1346config MICROCODE_LATE_FORCE_MINREV 1347 bool "Enforce late microcode loading minimal revision check" 1348 default n 1349 depends on MICROCODE_LATE_LOADING 1350 help 1351 To prevent that users load microcode late which modifies already 1352 in use features, newer microcode patches have a minimum revision field 1353 in the microcode header, which tells the kernel which minimum 1354 revision must be active in the CPU to safely load that new microcode 1355 late into the running system. If disabled the check will not 1356 be enforced but the kernel will be tainted when the minimal 1357 revision check fails. 1358 1359 This minimal revision check can also be controlled via the 1360 "microcode.minrev" parameter on the kernel command line. 1361 1362 If unsure say Y. 1363 1364config X86_MSR 1365 tristate "/dev/cpu/*/msr - Model-specific register support" 1366 help 1367 This device gives privileged processes access to the x86 1368 Model-Specific Registers (MSRs). It is a character device with 1369 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1370 MSR accesses are directed to a specific CPU on multi-processor 1371 systems. 1372 1373config X86_CPUID 1374 tristate "/dev/cpu/*/cpuid - CPU information support" 1375 help 1376 This device gives processes access to the x86 CPUID instruction to 1377 be executed on a specific processor. It is a character device 1378 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1379 /dev/cpu/31/cpuid. 1380 1381config HIGHMEM4G 1382 bool "High Memory Support" 1383 depends on X86_32 1384 help 1385 Linux can use up to 4 Gigabytes of physical memory on x86 systems. 1386 However, the address space of 32-bit x86 processors is only 4 1387 Gigabytes large. That means that, if you have a large amount of 1388 physical memory, not all of it can be "permanently mapped" by the 1389 kernel. The physical memory that's not permanently mapped is called 1390 "high memory". 1391 1392 If you are compiling a kernel which will never run on a machine with 1393 more than 1 Gigabyte total physical RAM, answer "off" here (default 1394 choice and suitable for most users). This will result in a "3GB/1GB" 1395 split: 3GB are mapped so that each process sees a 3GB virtual memory 1396 space and the remaining part of the 4GB virtual memory space is used 1397 by the kernel to permanently map as much physical memory as 1398 possible. 1399 1400 If the machine has between 1 and 4 Gigabytes physical RAM, then 1401 answer "Y" here. 1402 1403 If unsure, say N. 1404 1405choice 1406 prompt "Memory split" if EXPERT 1407 default VMSPLIT_3G 1408 depends on X86_32 1409 help 1410 Select the desired split between kernel and user memory. 1411 1412 If the address range available to the kernel is less than the 1413 physical memory installed, the remaining memory will be available 1414 as "high memory". Accessing high memory is a little more costly 1415 than low memory, as it needs to be mapped into the kernel first. 1416 Note that increasing the kernel address space limits the range 1417 available to user programs, making the address space there 1418 tighter. Selecting anything other than the default 3G/1G split 1419 will also likely make your kernel incompatible with binary-only 1420 kernel modules. 1421 1422 If you are not absolutely sure what you are doing, leave this 1423 option alone! 1424 1425 config VMSPLIT_3G 1426 bool "3G/1G user/kernel split" 1427 config VMSPLIT_3G_OPT 1428 depends on !X86_PAE 1429 bool "3G/1G user/kernel split (for full 1G low memory)" 1430 config VMSPLIT_2G 1431 bool "2G/2G user/kernel split" 1432 config VMSPLIT_2G_OPT 1433 depends on !X86_PAE 1434 bool "2G/2G user/kernel split (for full 2G low memory)" 1435 config VMSPLIT_1G 1436 bool "1G/3G user/kernel split" 1437endchoice 1438 1439config PAGE_OFFSET 1440 hex 1441 default 0xB0000000 if VMSPLIT_3G_OPT 1442 default 0x80000000 if VMSPLIT_2G 1443 default 0x78000000 if VMSPLIT_2G_OPT 1444 default 0x40000000 if VMSPLIT_1G 1445 default 0xC0000000 1446 depends on X86_32 1447 1448config HIGHMEM 1449 def_bool HIGHMEM4G 1450 1451config X86_PAE 1452 bool "PAE (Physical Address Extension) Support" 1453 depends on X86_32 && X86_HAVE_PAE 1454 select PHYS_ADDR_T_64BIT 1455 help 1456 PAE is required for NX support, and furthermore enables 1457 larger swapspace support for non-overcommit purposes. It 1458 has the cost of more pagetable lookup overhead, and also 1459 consumes more pagetable space per process. 1460 1461config X86_DIRECT_GBPAGES 1462 def_bool y 1463 depends on X86_64 1464 help 1465 Certain kernel features effectively disable kernel 1466 linear 1 GB mappings (even if the CPU otherwise 1467 supports them), so don't confuse the user by printing 1468 that we have them enabled. 1469 1470config X86_CPA_STATISTICS 1471 bool "Enable statistic for Change Page Attribute" 1472 depends on DEBUG_FS 1473 help 1474 Expose statistics about the Change Page Attribute mechanism, which 1475 helps to determine the effectiveness of preserving large and huge 1476 page mappings when mapping protections are changed. 1477 1478config X86_MEM_ENCRYPT 1479 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1480 select DYNAMIC_PHYSICAL_MASK 1481 def_bool n 1482 1483config AMD_MEM_ENCRYPT 1484 bool "AMD Secure Memory Encryption (SME) support" 1485 depends on X86_64 && CPU_SUP_AMD 1486 depends on EFI_STUB 1487 select DMA_COHERENT_POOL 1488 select ARCH_USE_MEMREMAP_PROT 1489 select INSTRUCTION_DECODER 1490 select ARCH_HAS_CC_PLATFORM 1491 select X86_MEM_ENCRYPT 1492 select UNACCEPTED_MEMORY 1493 select CRYPTO_LIB_AESGCM 1494 help 1495 Say yes to enable support for the encryption of system memory. 1496 This requires an AMD processor that supports Secure Memory 1497 Encryption (SME). 1498 1499# Common NUMA Features 1500config NUMA 1501 bool "NUMA Memory Allocation and Scheduler Support" 1502 depends on SMP 1503 depends on X86_64 1504 select USE_PERCPU_NUMA_NODE_ID 1505 select OF_NUMA if OF 1506 help 1507 Enable NUMA (Non-Uniform Memory Access) support. 1508 1509 The kernel will try to allocate memory used by a CPU on the 1510 local memory controller of the CPU and add some more 1511 NUMA awareness to the kernel. 1512 1513 For 64-bit this is recommended if the system is Intel Core i7 1514 (or later), AMD Opteron, or EM64T NUMA. 1515 1516 Otherwise, you should say N. 1517 1518config AMD_NUMA 1519 def_bool y 1520 prompt "Old style AMD Opteron NUMA detection" 1521 depends on X86_64 && NUMA && PCI 1522 help 1523 Enable AMD NUMA node topology detection. You should say Y here if 1524 you have a multi processor AMD system. This uses an old method to 1525 read the NUMA configuration directly from the builtin Northbridge 1526 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1527 which also takes priority if both are compiled in. 1528 1529config X86_64_ACPI_NUMA 1530 def_bool y 1531 prompt "ACPI NUMA detection" 1532 depends on X86_64 && NUMA && ACPI && PCI 1533 select ACPI_NUMA 1534 help 1535 Enable ACPI SRAT based node topology detection. 1536 1537config NODES_SHIFT 1538 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1539 range 1 10 1540 default "10" if MAXSMP 1541 default "6" if X86_64 1542 default "3" 1543 depends on NUMA 1544 help 1545 Specify the maximum number of NUMA Nodes available on the target 1546 system. Increases memory reserved to accommodate various tables. 1547 1548config ARCH_FLATMEM_ENABLE 1549 def_bool y 1550 depends on X86_32 && !NUMA 1551 1552config ARCH_SPARSEMEM_ENABLE 1553 def_bool y 1554 select SPARSEMEM_STATIC if X86_32 1555 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1556 select SPARSEMEM_VMEMMAP if X86_64 1557 1558config ARCH_SPARSEMEM_DEFAULT 1559 def_bool X86_64 || (NUMA && X86_32) 1560 1561config ARCH_SELECT_MEMORY_MODEL 1562 def_bool y 1563 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1564 1565config ARCH_MEMORY_PROBE 1566 bool "Enable sysfs memory/probe interface" 1567 depends on MEMORY_HOTPLUG 1568 help 1569 This option enables a sysfs memory/probe interface for testing. 1570 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1571 If you are unsure how to answer this question, answer N. 1572 1573config ARCH_PROC_KCORE_TEXT 1574 def_bool y 1575 depends on X86_64 && PROC_KCORE 1576 1577config ILLEGAL_POINTER_VALUE 1578 hex 1579 default 0 if X86_32 1580 default 0xdead000000000000 if X86_64 1581 1582config X86_PMEM_LEGACY_DEVICE 1583 bool 1584 1585config X86_PMEM_LEGACY 1586 tristate "Support non-standard NVDIMMs and ADR protected memory" 1587 depends on PHYS_ADDR_T_64BIT 1588 depends on BLK_DEV 1589 select X86_PMEM_LEGACY_DEVICE 1590 select NUMA_KEEP_MEMINFO if NUMA 1591 select LIBNVDIMM 1592 help 1593 Treat memory marked using the non-standard e820 type of 12 as used 1594 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1595 The kernel will offer these regions to the 'pmem' driver so 1596 they can be used for persistent storage. 1597 1598 Say Y if unsure. 1599 1600config X86_CHECK_BIOS_CORRUPTION 1601 bool "Check for low memory corruption" 1602 help 1603 Periodically check for memory corruption in low memory, which 1604 is suspected to be caused by BIOS. Even when enabled in the 1605 configuration, it is disabled at runtime. Enable it by 1606 setting "memory_corruption_check=1" on the kernel command 1607 line. By default it scans the low 64k of memory every 60 1608 seconds; see the memory_corruption_check_size and 1609 memory_corruption_check_period parameters in 1610 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1611 1612 When enabled with the default parameters, this option has 1613 almost no overhead, as it reserves a relatively small amount 1614 of memory and scans it infrequently. It both detects corruption 1615 and prevents it from affecting the running system. 1616 1617 It is, however, intended as a diagnostic tool; if repeatable 1618 BIOS-originated corruption always affects the same memory, 1619 you can use memmap= to prevent the kernel from using that 1620 memory. 1621 1622config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1623 bool "Set the default setting of memory_corruption_check" 1624 depends on X86_CHECK_BIOS_CORRUPTION 1625 default y 1626 help 1627 Set whether the default state of memory_corruption_check is 1628 on or off. 1629 1630config MATH_EMULATION 1631 bool 1632 depends on MODIFY_LDT_SYSCALL 1633 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1634 help 1635 Linux can emulate a math coprocessor (used for floating point 1636 operations) if you don't have one. 486DX and Pentium processors have 1637 a math coprocessor built in, 486SX and 386 do not, unless you added 1638 a 487DX or 387, respectively. (The messages during boot time can 1639 give you some hints here ["man dmesg"].) Everyone needs either a 1640 coprocessor or this emulation. 1641 1642 If you don't have a math coprocessor, you need to say Y here; if you 1643 say Y here even though you have a coprocessor, the coprocessor will 1644 be used nevertheless. (This behavior can be changed with the kernel 1645 command line option "no387", which comes handy if your coprocessor 1646 is broken. Try "man bootparam" or see the documentation of your boot 1647 loader (lilo or loadlin) about how to pass options to the kernel at 1648 boot time.) This means that it is a good idea to say Y here if you 1649 intend to use this kernel on different machines. 1650 1651 More information about the internals of the Linux math coprocessor 1652 emulation can be found in <file:arch/x86/math-emu/README>. 1653 1654 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1655 kernel, it won't hurt. 1656 1657config MTRR 1658 def_bool y 1659 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1660 help 1661 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1662 the Memory Type Range Registers (MTRRs) may be used to control 1663 processor access to memory ranges. This is most useful if you have 1664 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1665 allows bus write transfers to be combined into a larger transfer 1666 before bursting over the PCI/AGP bus. This can increase performance 1667 of image write operations 2.5 times or more. Saying Y here creates a 1668 /proc/mtrr file which may be used to manipulate your processor's 1669 MTRRs. Typically the X server should use this. 1670 1671 This code has a reasonably generic interface so that similar 1672 control registers on other processors can be easily supported 1673 as well: 1674 1675 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1676 Registers (ARRs) which provide a similar functionality to MTRRs. For 1677 these, the ARRs are used to emulate the MTRRs. 1678 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1679 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1680 write-combining. All of these processors are supported by this code 1681 and it makes sense to say Y here if you have one of them. 1682 1683 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1684 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1685 can lead to all sorts of problems, so it's good to say Y here. 1686 1687 You can safely say Y even if your machine doesn't have MTRRs, you'll 1688 just add about 9 KB to your kernel. 1689 1690 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1691 1692config MTRR_SANITIZER 1693 def_bool y 1694 prompt "MTRR cleanup support" 1695 depends on MTRR 1696 help 1697 Convert MTRR layout from continuous to discrete, so X drivers can 1698 add writeback entries. 1699 1700 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1701 The largest mtrr entry size for a continuous block can be set with 1702 mtrr_chunk_size. 1703 1704 If unsure, say Y. 1705 1706config MTRR_SANITIZER_ENABLE_DEFAULT 1707 int "MTRR cleanup enable value (0-1)" 1708 range 0 1 1709 default "0" 1710 depends on MTRR_SANITIZER 1711 help 1712 Enable mtrr cleanup default value 1713 1714config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1715 int "MTRR cleanup spare reg num (0-7)" 1716 range 0 7 1717 default "1" 1718 depends on MTRR_SANITIZER 1719 help 1720 mtrr cleanup spare entries default, it can be changed via 1721 mtrr_spare_reg_nr=N on the kernel command line. 1722 1723config X86_PAT 1724 def_bool y 1725 prompt "x86 PAT support" if EXPERT 1726 depends on MTRR 1727 select ARCH_USES_PG_ARCH_2 1728 help 1729 Use PAT attributes to setup page level cache control. 1730 1731 PATs are the modern equivalents of MTRRs and are much more 1732 flexible than MTRRs. 1733 1734 Say N here if you see bootup problems (boot crash, boot hang, 1735 spontaneous reboots) or a non-working video driver. 1736 1737 If unsure, say Y. 1738 1739config X86_UMIP 1740 def_bool y 1741 prompt "User Mode Instruction Prevention" if EXPERT 1742 help 1743 User Mode Instruction Prevention (UMIP) is a security feature in 1744 some x86 processors. If enabled, a general protection fault is 1745 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1746 executed in user mode. These instructions unnecessarily expose 1747 information about the hardware state. 1748 1749 The vast majority of applications do not use these instructions. 1750 For the very few that do, software emulation is provided in 1751 specific cases in protected and virtual-8086 modes. Emulated 1752 results are dummy. 1753 1754config CC_HAS_IBT 1755 # GCC >= 9 and binutils >= 2.29 1756 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1757 # Clang/LLVM >= 14 1758 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1759 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1760 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1761 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1762 $(as-instr,endbr64) 1763 1764config X86_CET 1765 def_bool n 1766 help 1767 CET features configured (Shadow stack or IBT) 1768 1769config X86_KERNEL_IBT 1770 prompt "Indirect Branch Tracking" 1771 def_bool y 1772 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1773 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1774 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1775 select OBJTOOL 1776 select X86_CET 1777 help 1778 Build the kernel with support for Indirect Branch Tracking, a 1779 hardware support course-grain forward-edge Control Flow Integrity 1780 protection. It enforces that all indirect calls must land on 1781 an ENDBR instruction, as such, the compiler will instrument the 1782 code with them to make this happen. 1783 1784 In addition to building the kernel with IBT, seal all functions that 1785 are not indirect call targets, avoiding them ever becoming one. 1786 1787 This requires LTO like objtool runs and will slow down the build. It 1788 does significantly reduce the number of ENDBR instructions in the 1789 kernel image. 1790 1791config X86_INTEL_MEMORY_PROTECTION_KEYS 1792 prompt "Memory Protection Keys" 1793 def_bool y 1794 # Note: only available in 64-bit mode 1795 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1796 select ARCH_USES_HIGH_VMA_FLAGS 1797 select ARCH_HAS_PKEYS 1798 help 1799 Memory Protection Keys provides a mechanism for enforcing 1800 page-based protections, but without requiring modification of the 1801 page tables when an application changes protection domains. 1802 1803 For details, see Documentation/core-api/protection-keys.rst 1804 1805 If unsure, say y. 1806 1807config ARCH_PKEY_BITS 1808 int 1809 default 4 1810 1811choice 1812 prompt "TSX enable mode" 1813 depends on CPU_SUP_INTEL 1814 default X86_INTEL_TSX_MODE_OFF 1815 help 1816 Intel's TSX (Transactional Synchronization Extensions) feature 1817 allows to optimize locking protocols through lock elision which 1818 can lead to a noticeable performance boost. 1819 1820 On the other hand it has been shown that TSX can be exploited 1821 to form side channel attacks (e.g. TAA) and chances are there 1822 will be more of those attacks discovered in the future. 1823 1824 Therefore TSX is not enabled by default (aka tsx=off). An admin 1825 might override this decision by tsx=on the command line parameter. 1826 Even with TSX enabled, the kernel will attempt to enable the best 1827 possible TAA mitigation setting depending on the microcode available 1828 for the particular machine. 1829 1830 This option allows to set the default tsx mode between tsx=on, =off 1831 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1832 details. 1833 1834 Say off if not sure, auto if TSX is in use but it should be used on safe 1835 platforms or on if TSX is in use and the security aspect of tsx is not 1836 relevant. 1837 1838config X86_INTEL_TSX_MODE_OFF 1839 bool "off" 1840 help 1841 TSX is disabled if possible - equals to tsx=off command line parameter. 1842 1843config X86_INTEL_TSX_MODE_ON 1844 bool "on" 1845 help 1846 TSX is always enabled on TSX capable HW - equals the tsx=on command 1847 line parameter. 1848 1849config X86_INTEL_TSX_MODE_AUTO 1850 bool "auto" 1851 help 1852 TSX is enabled on TSX capable HW that is believed to be safe against 1853 side channel attacks- equals the tsx=auto command line parameter. 1854endchoice 1855 1856config X86_SGX 1857 bool "Software Guard eXtensions (SGX)" 1858 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1859 select CRYPTO_LIB_SHA256 1860 select MMU_NOTIFIER 1861 select NUMA_KEEP_MEMINFO if NUMA 1862 select XARRAY_MULTI 1863 help 1864 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1865 that can be used by applications to set aside private regions of code 1866 and data, referred to as enclaves. An enclave's private memory can 1867 only be accessed by code running within the enclave. Accesses from 1868 outside the enclave, including other enclaves, are disallowed by 1869 hardware. 1870 1871 If unsure, say N. 1872 1873config X86_USER_SHADOW_STACK 1874 bool "X86 userspace shadow stack" 1875 depends on AS_WRUSS 1876 depends on X86_64 1877 select ARCH_USES_HIGH_VMA_FLAGS 1878 select ARCH_HAS_USER_SHADOW_STACK 1879 select X86_CET 1880 help 1881 Shadow stack protection is a hardware feature that detects function 1882 return address corruption. This helps mitigate ROP attacks. 1883 Applications must be enabled to use it, and old userspace does not 1884 get protection "for free". 1885 1886 CPUs supporting shadow stacks were first released in 2020. 1887 1888 See Documentation/arch/x86/shstk.rst for more information. 1889 1890 If unsure, say N. 1891 1892config INTEL_TDX_HOST 1893 bool "Intel Trust Domain Extensions (TDX) host support" 1894 depends on CPU_SUP_INTEL 1895 depends on X86_64 1896 depends on KVM_INTEL 1897 depends on X86_X2APIC 1898 select ARCH_KEEP_MEMBLOCK 1899 depends on CONTIG_ALLOC 1900 depends on !KEXEC_CORE 1901 depends on X86_MCE 1902 help 1903 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1904 host and certain physical attacks. This option enables necessary TDX 1905 support in the host kernel to run confidential VMs. 1906 1907 If unsure, say N. 1908 1909config EFI 1910 bool "EFI runtime service support" 1911 depends on ACPI 1912 select UCS2_STRING 1913 select EFI_RUNTIME_WRAPPERS 1914 select ARCH_USE_MEMREMAP_PROT 1915 select EFI_RUNTIME_MAP if KEXEC_CORE 1916 help 1917 This enables the kernel to use EFI runtime services that are 1918 available (such as the EFI variable services). 1919 1920 This option is only useful on systems that have EFI firmware. 1921 In addition, you should use the latest ELILO loader available 1922 at <http://elilo.sourceforge.net> in order to take advantage 1923 of EFI runtime services. However, even with this option, the 1924 resultant kernel should continue to boot on existing non-EFI 1925 platforms. 1926 1927config EFI_STUB 1928 bool "EFI stub support" 1929 depends on EFI 1930 select RELOCATABLE 1931 help 1932 This kernel feature allows a bzImage to be loaded directly 1933 by EFI firmware without the use of a bootloader. 1934 1935 See Documentation/admin-guide/efi-stub.rst for more information. 1936 1937config EFI_HANDOVER_PROTOCOL 1938 bool "EFI handover protocol (DEPRECATED)" 1939 depends on EFI_STUB 1940 default y 1941 help 1942 Select this in order to include support for the deprecated EFI 1943 handover protocol, which defines alternative entry points into the 1944 EFI stub. This is a practice that has no basis in the UEFI 1945 specification, and requires a priori knowledge on the part of the 1946 bootloader about Linux/x86 specific ways of passing the command line 1947 and initrd, and where in memory those assets may be loaded. 1948 1949 If in doubt, say Y. Even though the corresponding support is not 1950 present in upstream GRUB or other bootloaders, most distros build 1951 GRUB with numerous downstream patches applied, and may rely on the 1952 handover protocol as as result. 1953 1954config EFI_MIXED 1955 bool "EFI mixed-mode support" 1956 depends on EFI_STUB && X86_64 1957 help 1958 Enabling this feature allows a 64-bit kernel to be booted 1959 on a 32-bit firmware, provided that your CPU supports 64-bit 1960 mode. 1961 1962 Note that it is not possible to boot a mixed-mode enabled 1963 kernel via the EFI boot stub - a bootloader that supports 1964 the EFI handover protocol must be used. 1965 1966 If unsure, say N. 1967 1968config EFI_RUNTIME_MAP 1969 bool "Export EFI runtime maps to sysfs" if EXPERT 1970 depends on EFI 1971 help 1972 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 1973 That memory map is required by the 2nd kernel to set up EFI virtual 1974 mappings after kexec, but can also be used for debugging purposes. 1975 1976 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 1977 1978source "kernel/Kconfig.hz" 1979 1980config ARCH_SUPPORTS_KEXEC 1981 def_bool y 1982 1983config ARCH_SUPPORTS_KEXEC_FILE 1984 def_bool X86_64 1985 1986config ARCH_SELECTS_KEXEC_FILE 1987 def_bool y 1988 depends on KEXEC_FILE 1989 select HAVE_IMA_KEXEC if IMA 1990 1991config ARCH_SUPPORTS_KEXEC_PURGATORY 1992 def_bool y 1993 1994config ARCH_SUPPORTS_KEXEC_SIG 1995 def_bool y 1996 1997config ARCH_SUPPORTS_KEXEC_SIG_FORCE 1998 def_bool y 1999 2000config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2001 def_bool y 2002 2003config ARCH_SUPPORTS_KEXEC_JUMP 2004 def_bool y 2005 2006config ARCH_SUPPORTS_KEXEC_HANDOVER 2007 def_bool X86_64 2008 2009config ARCH_SUPPORTS_CRASH_DUMP 2010 def_bool X86_64 || (X86_32 && HIGHMEM) 2011 2012config ARCH_DEFAULT_CRASH_DUMP 2013 def_bool y 2014 2015config ARCH_SUPPORTS_CRASH_HOTPLUG 2016 def_bool y 2017 2018config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2019 def_bool CRASH_RESERVE 2020 2021config PHYSICAL_START 2022 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2023 default "0x1000000" 2024 help 2025 This gives the physical address where the kernel is loaded. 2026 2027 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2028 will decompress itself to above physical address and run from there. 2029 Otherwise, bzImage will run from the address where it has been loaded 2030 by the boot loader. The only exception is if it is loaded below the 2031 above physical address, in which case it will relocate itself there. 2032 2033 In normal kdump cases one does not have to set/change this option 2034 as now bzImage can be compiled as a completely relocatable image 2035 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2036 address. This option is mainly useful for the folks who don't want 2037 to use a bzImage for capturing the crash dump and want to use a 2038 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2039 to be specifically compiled to run from a specific memory area 2040 (normally a reserved region) and this option comes handy. 2041 2042 So if you are using bzImage for capturing the crash dump, 2043 leave the value here unchanged to 0x1000000 and set 2044 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2045 for capturing the crash dump change this value to start of 2046 the reserved region. In other words, it can be set based on 2047 the "X" value as specified in the "crashkernel=YM@XM" 2048 command line boot parameter passed to the panic-ed 2049 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2050 for more details about crash dumps. 2051 2052 Usage of bzImage for capturing the crash dump is recommended as 2053 one does not have to build two kernels. Same kernel can be used 2054 as production kernel and capture kernel. Above option should have 2055 gone away after relocatable bzImage support is introduced. But it 2056 is present because there are users out there who continue to use 2057 vmlinux for dump capture. This option should go away down the 2058 line. 2059 2060 Don't change this unless you know what you are doing. 2061 2062config RELOCATABLE 2063 bool "Build a relocatable kernel" 2064 default y 2065 help 2066 This builds a kernel image that retains relocation information 2067 so it can be loaded someplace besides the default 1MB. 2068 The relocations tend to make the kernel binary about 10% larger, 2069 but are discarded at runtime. 2070 2071 One use is for the kexec on panic case where the recovery kernel 2072 must live at a different physical address than the primary 2073 kernel. 2074 2075 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2076 it has been loaded at and the compile time physical address 2077 (CONFIG_PHYSICAL_START) is used as the minimum location. 2078 2079config RANDOMIZE_BASE 2080 bool "Randomize the address of the kernel image (KASLR)" 2081 depends on RELOCATABLE 2082 default y 2083 help 2084 In support of Kernel Address Space Layout Randomization (KASLR), 2085 this randomizes the physical address at which the kernel image 2086 is decompressed and the virtual address where the kernel 2087 image is mapped, as a security feature that deters exploit 2088 attempts relying on knowledge of the location of kernel 2089 code internals. 2090 2091 On 64-bit, the kernel physical and virtual addresses are 2092 randomized separately. The physical address will be anywhere 2093 between 16MB and the top of physical memory (up to 64TB). The 2094 virtual address will be randomized from 16MB up to 1GB (9 bits 2095 of entropy). Note that this also reduces the memory space 2096 available to kernel modules from 1.5GB to 1GB. 2097 2098 On 32-bit, the kernel physical and virtual addresses are 2099 randomized together. They will be randomized from 16MB up to 2100 512MB (8 bits of entropy). 2101 2102 Entropy is generated using the RDRAND instruction if it is 2103 supported. If RDTSC is supported, its value is mixed into 2104 the entropy pool as well. If neither RDRAND nor RDTSC are 2105 supported, then entropy is read from the i8254 timer. The 2106 usable entropy is limited by the kernel being built using 2107 2GB addressing, and that PHYSICAL_ALIGN must be at a 2108 minimum of 2MB. As a result, only 10 bits of entropy are 2109 theoretically possible, but the implementations are further 2110 limited due to memory layouts. 2111 2112 If unsure, say Y. 2113 2114# Relocation on x86 needs some additional build support 2115config X86_NEED_RELOCS 2116 def_bool y 2117 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2118 select ARCH_VMLINUX_NEEDS_RELOCS 2119 2120config PHYSICAL_ALIGN 2121 hex "Alignment value to which kernel should be aligned" 2122 default "0x200000" 2123 range 0x2000 0x1000000 if X86_32 2124 range 0x200000 0x1000000 if X86_64 2125 help 2126 This value puts the alignment restrictions on physical address 2127 where kernel is loaded and run from. Kernel is compiled for an 2128 address which meets above alignment restriction. 2129 2130 If bootloader loads the kernel at a non-aligned address and 2131 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2132 address aligned to above value and run from there. 2133 2134 If bootloader loads the kernel at a non-aligned address and 2135 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2136 load address and decompress itself to the address it has been 2137 compiled for and run from there. The address for which kernel is 2138 compiled already meets above alignment restrictions. Hence the 2139 end result is that kernel runs from a physical address meeting 2140 above alignment restrictions. 2141 2142 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2143 this value must be a multiple of 0x200000. 2144 2145 Don't change this unless you know what you are doing. 2146 2147config RANDOMIZE_MEMORY 2148 bool "Randomize the kernel memory sections" 2149 depends on X86_64 2150 depends on RANDOMIZE_BASE 2151 default RANDOMIZE_BASE 2152 help 2153 Randomizes the base virtual address of kernel memory sections 2154 (physical memory mapping, vmalloc & vmemmap). This security feature 2155 makes exploits relying on predictable memory locations less reliable. 2156 2157 The order of allocations remains unchanged. Entropy is generated in 2158 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2159 configuration have in average 30,000 different possible virtual 2160 addresses for each memory section. 2161 2162 If unsure, say Y. 2163 2164config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2165 hex "Physical memory mapping padding" if EXPERT 2166 depends on RANDOMIZE_MEMORY 2167 default "0xa" if MEMORY_HOTPLUG 2168 default "0x0" 2169 range 0x1 0x40 if MEMORY_HOTPLUG 2170 range 0x0 0x40 2171 help 2172 Define the padding in terabytes added to the existing physical 2173 memory size during kernel memory randomization. It is useful 2174 for memory hotplug support but reduces the entropy available for 2175 address randomization. 2176 2177 If unsure, leave at the default value. 2178 2179config ADDRESS_MASKING 2180 bool "Linear Address Masking support" 2181 depends on X86_64 2182 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS 2183 help 2184 Linear Address Masking (LAM) modifies the checking that is applied 2185 to 64-bit linear addresses, allowing software to use of the 2186 untranslated address bits for metadata. 2187 2188 The capability can be used for efficient address sanitizers (ASAN) 2189 implementation and for optimizations in JITs. 2190 2191config HOTPLUG_CPU 2192 def_bool y 2193 depends on SMP 2194 2195config COMPAT_VDSO 2196 def_bool n 2197 prompt "Workaround for glibc 2.3.2 / 2.3.3 (released in year 2003/2004)" 2198 depends on COMPAT_32 2199 help 2200 Certain buggy versions of glibc will crash if they are 2201 presented with a 32-bit vDSO that is not mapped at the address 2202 indicated in its segment table. 2203 2204 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2205 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2206 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2207 the only released version with the bug, but OpenSUSE 9 2208 contains a buggy "glibc 2.3.2". 2209 2210 The symptom of the bug is that everything crashes on startup, saying: 2211 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2212 2213 Saying Y here changes the default value of the vdso32 boot 2214 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2215 This works around the glibc bug but hurts performance. 2216 2217 If unsure, say N: if you are compiling your own kernel, you 2218 are unlikely to be using a buggy version of glibc. 2219 2220choice 2221 prompt "vsyscall table for legacy applications" 2222 depends on X86_64 2223 default LEGACY_VSYSCALL_XONLY 2224 help 2225 Legacy user code that does not know how to find the vDSO expects 2226 to be able to issue three syscalls by calling fixed addresses in 2227 kernel space. Since this location is not randomized with ASLR, 2228 it can be used to assist security vulnerability exploitation. 2229 2230 This setting can be changed at boot time via the kernel command 2231 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2232 is deprecated and can only be enabled using the kernel command 2233 line. 2234 2235 On a system with recent enough glibc (2.14 or newer) and no 2236 static binaries, you can say None without a performance penalty 2237 to improve security. 2238 2239 If unsure, select "Emulate execution only". 2240 2241 config LEGACY_VSYSCALL_XONLY 2242 bool "Emulate execution only" 2243 help 2244 The kernel traps and emulates calls into the fixed vsyscall 2245 address mapping and does not allow reads. This 2246 configuration is recommended when userspace might use the 2247 legacy vsyscall area but support for legacy binary 2248 instrumentation of legacy code is not needed. It mitigates 2249 certain uses of the vsyscall area as an ASLR-bypassing 2250 buffer. 2251 2252 config LEGACY_VSYSCALL_NONE 2253 bool "None" 2254 help 2255 There will be no vsyscall mapping at all. This will 2256 eliminate any risk of ASLR bypass due to the vsyscall 2257 fixed address mapping. Attempts to use the vsyscalls 2258 will be reported to dmesg, so that either old or 2259 malicious userspace programs can be identified. 2260 2261endchoice 2262 2263config CMDLINE_BOOL 2264 bool "Built-in kernel command line" 2265 help 2266 Allow for specifying boot arguments to the kernel at 2267 build time. On some systems (e.g. embedded ones), it is 2268 necessary or convenient to provide some or all of the 2269 kernel boot arguments with the kernel itself (that is, 2270 to not rely on the boot loader to provide them.) 2271 2272 To compile command line arguments into the kernel, 2273 set this option to 'Y', then fill in the 2274 boot arguments in CONFIG_CMDLINE. 2275 2276 Systems with fully functional boot loaders (i.e. non-embedded) 2277 should leave this option set to 'N'. 2278 2279config CMDLINE 2280 string "Built-in kernel command string" 2281 depends on CMDLINE_BOOL 2282 default "" 2283 help 2284 Enter arguments here that should be compiled into the kernel 2285 image and used at boot time. If the boot loader provides a 2286 command line at boot time, it is appended to this string to 2287 form the full kernel command line, when the system boots. 2288 2289 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2290 change this behavior. 2291 2292 In most cases, the command line (whether built-in or provided 2293 by the boot loader) should specify the device for the root 2294 file system. 2295 2296config CMDLINE_OVERRIDE 2297 bool "Built-in command line overrides boot loader arguments" 2298 depends on CMDLINE_BOOL && CMDLINE != "" 2299 help 2300 Set this option to 'Y' to have the kernel ignore the boot loader 2301 command line, and use ONLY the built-in command line. 2302 2303 This is used to work around broken boot loaders. This should 2304 be set to 'N' under normal conditions. 2305 2306config MODIFY_LDT_SYSCALL 2307 bool "Enable the LDT (local descriptor table)" if EXPERT 2308 default y 2309 help 2310 Linux can allow user programs to install a per-process x86 2311 Local Descriptor Table (LDT) using the modify_ldt(2) system 2312 call. This is required to run 16-bit or segmented code such as 2313 DOSEMU or some Wine programs. It is also used by some very old 2314 threading libraries. 2315 2316 Enabling this feature adds a small amount of overhead to 2317 context switches and increases the low-level kernel attack 2318 surface. Disabling it removes the modify_ldt(2) system call. 2319 2320 Saying 'N' here may make sense for embedded or server kernels. 2321 2322config STRICT_SIGALTSTACK_SIZE 2323 bool "Enforce strict size checking for sigaltstack" 2324 depends on DYNAMIC_SIGFRAME 2325 help 2326 For historical reasons MINSIGSTKSZ is a constant which became 2327 already too small with AVX512 support. Add a mechanism to 2328 enforce strict checking of the sigaltstack size against the 2329 real size of the FPU frame. This option enables the check 2330 by default. It can also be controlled via the kernel command 2331 line option 'strict_sas_size' independent of this config 2332 switch. Enabling it might break existing applications which 2333 allocate a too small sigaltstack but 'work' because they 2334 never get a signal delivered. 2335 2336 Say 'N' unless you want to really enforce this check. 2337 2338config CFI_AUTO_DEFAULT 2339 bool "Attempt to use FineIBT by default at boot time" 2340 depends on FINEIBT 2341 depends on !RUST || RUSTC_VERSION >= 108800 2342 default y 2343 help 2344 Attempt to use FineIBT by default at boot time. If enabled, 2345 this is the same as booting with "cfi=auto". If disabled, 2346 this is the same as booting with "cfi=kcfi". 2347 2348source "kernel/livepatch/Kconfig" 2349 2350config X86_BUS_LOCK_DETECT 2351 bool "Split Lock Detect and Bus Lock Detect support" 2352 depends on CPU_SUP_INTEL || CPU_SUP_AMD 2353 default y 2354 help 2355 Enable Split Lock Detect and Bus Lock Detect functionalities. 2356 See <file:Documentation/arch/x86/buslock.rst> for more information. 2357 2358endmenu 2359 2360config CC_HAS_NAMED_AS 2361 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null) 2362 depends on CC_IS_GCC 2363 2364# 2365# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN) 2366# are incompatible with named address spaces with GCC < 13.3 2367# (see GCC PR sanitizer/111736 and also PR sanitizer/115172). 2368# 2369 2370config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2371 def_bool y 2372 depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300 2373 depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200 2374 2375config USE_X86_SEG_SUPPORT 2376 def_bool CC_HAS_NAMED_AS 2377 depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS 2378 2379config CC_HAS_SLS 2380 def_bool $(cc-option,-mharden-sls=all) 2381 2382config CC_HAS_RETURN_THUNK 2383 def_bool $(cc-option,-mfunction-return=thunk-extern) 2384 2385config CC_HAS_ENTRY_PADDING 2386 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2387 2388config CC_HAS_KCFI_ARITY 2389 def_bool $(cc-option,-fsanitize=kcfi -fsanitize-kcfi-arity) 2390 depends on CC_IS_CLANG && !RUST 2391 2392config FUNCTION_PADDING_CFI 2393 int 2394 default 59 if FUNCTION_ALIGNMENT_64B 2395 default 27 if FUNCTION_ALIGNMENT_32B 2396 default 11 if FUNCTION_ALIGNMENT_16B 2397 default 3 if FUNCTION_ALIGNMENT_8B 2398 default 0 2399 2400# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2401# except Kconfig can't do arithmetic :/ 2402config FUNCTION_PADDING_BYTES 2403 int 2404 default FUNCTION_PADDING_CFI if CFI_CLANG 2405 default FUNCTION_ALIGNMENT 2406 2407config CALL_PADDING 2408 def_bool n 2409 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2410 select FUNCTION_ALIGNMENT_16B 2411 2412config FINEIBT 2413 def_bool y 2414 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE 2415 select CALL_PADDING 2416 2417config FINEIBT_BHI 2418 def_bool y 2419 depends on FINEIBT && CC_HAS_KCFI_ARITY 2420 2421config HAVE_CALL_THUNKS 2422 def_bool y 2423 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2424 2425config CALL_THUNKS 2426 def_bool n 2427 select CALL_PADDING 2428 2429config PREFIX_SYMBOLS 2430 def_bool y 2431 depends on CALL_PADDING && !CFI_CLANG 2432 2433menuconfig CPU_MITIGATIONS 2434 bool "Mitigations for CPU vulnerabilities" 2435 default y 2436 help 2437 Say Y here to enable options which enable mitigations for hardware 2438 vulnerabilities (usually related to speculative execution). 2439 Mitigations can be disabled or restricted to SMT systems at runtime 2440 via the "mitigations" kernel parameter. 2441 2442 If you say N, all mitigations will be disabled. This CANNOT be 2443 overridden at runtime. 2444 2445 Say 'Y', unless you really know what you are doing. 2446 2447if CPU_MITIGATIONS 2448 2449config MITIGATION_PAGE_TABLE_ISOLATION 2450 bool "Remove the kernel mapping in user mode" 2451 default y 2452 depends on (X86_64 || X86_PAE) 2453 help 2454 This feature reduces the number of hardware side channels by 2455 ensuring that the majority of kernel addresses are not mapped 2456 into userspace. 2457 2458 See Documentation/arch/x86/pti.rst for more details. 2459 2460config MITIGATION_RETPOLINE 2461 bool "Avoid speculative indirect branches in kernel" 2462 select OBJTOOL if HAVE_OBJTOOL 2463 default y 2464 help 2465 Compile kernel with the retpoline compiler options to guard against 2466 kernel-to-user data leaks by avoiding speculative indirect 2467 branches. Requires a compiler with -mindirect-branch=thunk-extern 2468 support for full protection. The kernel may run slower. 2469 2470config MITIGATION_RETHUNK 2471 bool "Enable return-thunks" 2472 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2473 select OBJTOOL if HAVE_OBJTOOL 2474 default y if X86_64 2475 help 2476 Compile the kernel with the return-thunks compiler option to guard 2477 against kernel-to-user data leaks by avoiding return speculation. 2478 Requires a compiler with -mfunction-return=thunk-extern 2479 support for full protection. The kernel may run slower. 2480 2481config MITIGATION_UNRET_ENTRY 2482 bool "Enable UNRET on kernel entry" 2483 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2484 default y 2485 help 2486 Compile the kernel with support for the retbleed=unret mitigation. 2487 2488config MITIGATION_CALL_DEPTH_TRACKING 2489 bool "Mitigate RSB underflow with call depth tracking" 2490 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2491 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2492 select CALL_THUNKS 2493 default y 2494 help 2495 Compile the kernel with call depth tracking to mitigate the Intel 2496 SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off 2497 by default and needs to be enabled on the kernel command line via the 2498 retbleed=stuff option. For non-affected systems the overhead of this 2499 option is marginal as the call depth tracking is using run-time 2500 generated call thunks in a compiler generated padding area and call 2501 patching. This increases text size by ~5%. For non affected systems 2502 this space is unused. On affected SKL systems this results in a 2503 significant performance gain over the IBRS mitigation. 2504 2505config CALL_THUNKS_DEBUG 2506 bool "Enable call thunks and call depth tracking debugging" 2507 depends on MITIGATION_CALL_DEPTH_TRACKING 2508 select FUNCTION_ALIGNMENT_32B 2509 default n 2510 help 2511 Enable call/ret counters for imbalance detection and build in 2512 a noisy dmesg about callthunks generation and call patching for 2513 trouble shooting. The debug prints need to be enabled on the 2514 kernel command line with 'debug-callthunks'. 2515 Only enable this when you are debugging call thunks as this 2516 creates a noticeable runtime overhead. If unsure say N. 2517 2518config MITIGATION_IBPB_ENTRY 2519 bool "Enable IBPB on kernel entry" 2520 depends on CPU_SUP_AMD && X86_64 2521 default y 2522 help 2523 Compile the kernel with support for the retbleed=ibpb and 2524 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations. 2525 2526config MITIGATION_IBRS_ENTRY 2527 bool "Enable IBRS on kernel entry" 2528 depends on CPU_SUP_INTEL && X86_64 2529 default y 2530 help 2531 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2532 This mitigates both spectre_v2 and retbleed at great cost to 2533 performance. 2534 2535config MITIGATION_SRSO 2536 bool "Mitigate speculative RAS overflow on AMD" 2537 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2538 default y 2539 help 2540 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2541 2542config MITIGATION_SLS 2543 bool "Mitigate Straight-Line-Speculation" 2544 depends on CC_HAS_SLS && X86_64 2545 select OBJTOOL if HAVE_OBJTOOL 2546 default n 2547 help 2548 Compile the kernel with straight-line-speculation options to guard 2549 against straight line speculation. The kernel image might be slightly 2550 larger. 2551 2552config MITIGATION_GDS 2553 bool "Mitigate Gather Data Sampling" 2554 depends on CPU_SUP_INTEL 2555 default y 2556 help 2557 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware 2558 vulnerability which allows unprivileged speculative access to data 2559 which was previously stored in vector registers. The attacker uses gather 2560 instructions to infer the stale vector register data. 2561 2562config MITIGATION_RFDS 2563 bool "RFDS Mitigation" 2564 depends on CPU_SUP_INTEL 2565 default y 2566 help 2567 Enable mitigation for Register File Data Sampling (RFDS) by default. 2568 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2569 allows unprivileged speculative access to stale data previously 2570 stored in floating point, vector and integer registers. 2571 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2572 2573config MITIGATION_SPECTRE_BHI 2574 bool "Mitigate Spectre-BHB (Branch History Injection)" 2575 depends on CPU_SUP_INTEL 2576 default y 2577 help 2578 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2579 where the branch history buffer is poisoned to speculatively steer 2580 indirect branches. 2581 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2582 2583config MITIGATION_MDS 2584 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug" 2585 depends on CPU_SUP_INTEL 2586 default y 2587 help 2588 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is 2589 a hardware vulnerability which allows unprivileged speculative access 2590 to data which is available in various CPU internal buffers. 2591 See also <file:Documentation/admin-guide/hw-vuln/mds.rst> 2592 2593config MITIGATION_TAA 2594 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug" 2595 depends on CPU_SUP_INTEL 2596 default y 2597 help 2598 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware 2599 vulnerability that allows unprivileged speculative access to data 2600 which is available in various CPU internal buffers by using 2601 asynchronous aborts within an Intel TSX transactional region. 2602 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst> 2603 2604config MITIGATION_MMIO_STALE_DATA 2605 bool "Mitigate MMIO Stale Data hardware bug" 2606 depends on CPU_SUP_INTEL 2607 default y 2608 help 2609 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO 2610 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO) 2611 vulnerabilities that can expose data. The vulnerabilities require the 2612 attacker to have access to MMIO. 2613 See also 2614 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst> 2615 2616config MITIGATION_L1TF 2617 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug" 2618 depends on CPU_SUP_INTEL 2619 default y 2620 help 2621 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a 2622 hardware vulnerability which allows unprivileged speculative access to data 2623 available in the Level 1 Data Cache. 2624 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst 2625 2626config MITIGATION_RETBLEED 2627 bool "Mitigate RETBleed hardware bug" 2628 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY 2629 default y 2630 help 2631 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution 2632 with Return Instructions) vulnerability. RETBleed is a speculative 2633 execution attack which takes advantage of microarchitectural behavior 2634 in many modern microprocessors, similar to Spectre v2. An 2635 unprivileged attacker can use these flaws to bypass conventional 2636 memory security restrictions to gain read access to privileged memory 2637 that would otherwise be inaccessible. 2638 2639config MITIGATION_SPECTRE_V1 2640 bool "Mitigate SPECTRE V1 hardware bug" 2641 default y 2642 help 2643 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a 2644 class of side channel attacks that takes advantage of speculative 2645 execution that bypasses conditional branch instructions used for 2646 memory access bounds check. 2647 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2648 2649config MITIGATION_SPECTRE_V2 2650 bool "Mitigate SPECTRE V2 hardware bug" 2651 default y 2652 help 2653 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre 2654 V2 is a class of side channel attacks that takes advantage of 2655 indirect branch predictors inside the processor. In Spectre variant 2 2656 attacks, the attacker can steer speculative indirect branches in the 2657 victim to gadget code by poisoning the branch target buffer of a CPU 2658 used for predicting indirect branch addresses. 2659 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2660 2661config MITIGATION_SRBDS 2662 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug" 2663 depends on CPU_SUP_INTEL 2664 default y 2665 help 2666 Enable mitigation for Special Register Buffer Data Sampling (SRBDS). 2667 SRBDS is a hardware vulnerability that allows Microarchitectural Data 2668 Sampling (MDS) techniques to infer values returned from special 2669 register accesses. An unprivileged user can extract values returned 2670 from RDRAND and RDSEED executed on another core or sibling thread 2671 using MDS techniques. 2672 See also 2673 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst> 2674 2675config MITIGATION_SSB 2676 bool "Mitigate Speculative Store Bypass (SSB) hardware bug" 2677 default y 2678 help 2679 Enable mitigation for Speculative Store Bypass (SSB). SSB is a 2680 hardware security vulnerability and its exploitation takes advantage 2681 of speculative execution in a similar way to the Meltdown and Spectre 2682 security vulnerabilities. 2683 2684config MITIGATION_ITS 2685 bool "Enable Indirect Target Selection mitigation" 2686 depends on CPU_SUP_INTEL && X86_64 2687 depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK 2688 select EXECMEM 2689 default y 2690 help 2691 Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in 2692 BPU on some Intel CPUs that may allow Spectre V2 style attacks. If 2693 disabled, mitigation cannot be enabled via cmdline. 2694 See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst> 2695 2696config MITIGATION_TSA 2697 bool "Mitigate Transient Scheduler Attacks" 2698 depends on CPU_SUP_AMD 2699 default y 2700 help 2701 Enable mitigation for Transient Scheduler Attacks. TSA is a hardware 2702 security vulnerability on AMD CPUs which can lead to forwarding of 2703 invalid info to subsequent instructions and thus can affect their 2704 timing and thereby cause a leakage. 2705endif 2706 2707config ARCH_HAS_ADD_PAGES 2708 def_bool y 2709 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2710 2711menu "Power management and ACPI options" 2712 2713config ARCH_HIBERNATION_HEADER 2714 def_bool y 2715 depends on HIBERNATION 2716 2717source "kernel/power/Kconfig" 2718 2719source "drivers/acpi/Kconfig" 2720 2721config X86_APM_BOOT 2722 def_bool y 2723 depends on APM 2724 2725menuconfig APM 2726 tristate "APM (Advanced Power Management) BIOS support" 2727 depends on X86_32 && PM_SLEEP 2728 help 2729 APM is a BIOS specification for saving power using several different 2730 techniques. This is mostly useful for battery powered laptops with 2731 APM compliant BIOSes. If you say Y here, the system time will be 2732 reset after a RESUME operation, the /proc/apm device will provide 2733 battery status information, and user-space programs will receive 2734 notification of APM "events" (e.g. battery status change). 2735 2736 If you select "Y" here, you can disable actual use of the APM 2737 BIOS by passing the "apm=off" option to the kernel at boot time. 2738 2739 Note that the APM support is almost completely disabled for 2740 machines with more than one CPU. 2741 2742 In order to use APM, you will need supporting software. For location 2743 and more information, read <file:Documentation/power/apm-acpi.rst> 2744 and the Battery Powered Linux mini-HOWTO, available from 2745 <http://www.tldp.org/docs.html#howto>. 2746 2747 This driver does not spin down disk drives (see the hdparm(8) 2748 manpage ("man 8 hdparm") for that), and it doesn't turn off 2749 VESA-compliant "green" monitors. 2750 2751 This driver does not support the TI 4000M TravelMate and the ACER 2752 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2753 desktop machines also don't have compliant BIOSes, and this driver 2754 may cause those machines to panic during the boot phase. 2755 2756 Generally, if you don't have a battery in your machine, there isn't 2757 much point in using this driver and you should say N. If you get 2758 random kernel OOPSes or reboots that don't seem to be related to 2759 anything, try disabling/enabling this option (or disabling/enabling 2760 APM in your BIOS). 2761 2762 Some other things you should try when experiencing seemingly random, 2763 "weird" problems: 2764 2765 1) make sure that you have enough swap space and that it is 2766 enabled. 2767 2) pass the "idle=poll" option to the kernel 2768 3) switch on floating point emulation in the kernel and pass 2769 the "no387" option to the kernel 2770 4) pass the "floppy=nodma" option to the kernel 2771 5) pass the "mem=4M" option to the kernel (thereby disabling 2772 all but the first 4 MB of RAM) 2773 6) make sure that the CPU is not over clocked. 2774 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2775 8) disable the cache from your BIOS settings 2776 9) install a fan for the video card or exchange video RAM 2777 10) install a better fan for the CPU 2778 11) exchange RAM chips 2779 12) exchange the motherboard. 2780 2781 To compile this driver as a module, choose M here: the 2782 module will be called apm. 2783 2784if APM 2785 2786config APM_IGNORE_USER_SUSPEND 2787 bool "Ignore USER SUSPEND" 2788 help 2789 This option will ignore USER SUSPEND requests. On machines with a 2790 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2791 series notebooks, it is necessary to say Y because of a BIOS bug. 2792 2793config APM_DO_ENABLE 2794 bool "Enable PM at boot time" 2795 help 2796 Enable APM features at boot time. From page 36 of the APM BIOS 2797 specification: "When disabled, the APM BIOS does not automatically 2798 power manage devices, enter the Standby State, enter the Suspend 2799 State, or take power saving steps in response to CPU Idle calls." 2800 This driver will make CPU Idle calls when Linux is idle (unless this 2801 feature is turned off -- see "Do CPU IDLE calls", below). This 2802 should always save battery power, but more complicated APM features 2803 will be dependent on your BIOS implementation. You may need to turn 2804 this option off if your computer hangs at boot time when using APM 2805 support, or if it beeps continuously instead of suspending. Turn 2806 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2807 T400CDT. This is off by default since most machines do fine without 2808 this feature. 2809 2810config APM_CPU_IDLE 2811 depends on CPU_IDLE 2812 bool "Make CPU Idle calls when idle" 2813 help 2814 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2815 On some machines, this can activate improved power savings, such as 2816 a slowed CPU clock rate, when the machine is idle. These idle calls 2817 are made after the idle loop has run for some length of time (e.g., 2818 333 mS). On some machines, this will cause a hang at boot time or 2819 whenever the CPU becomes idle. (On machines with more than one CPU, 2820 this option does nothing.) 2821 2822config APM_DISPLAY_BLANK 2823 bool "Enable console blanking using APM" 2824 help 2825 Enable console blanking using the APM. Some laptops can use this to 2826 turn off the LCD backlight when the screen blanker of the Linux 2827 virtual console blanks the screen. Note that this is only used by 2828 the virtual console screen blanker, and won't turn off the backlight 2829 when using the X Window system. This also doesn't have anything to 2830 do with your VESA-compliant power-saving monitor. Further, this 2831 option doesn't work for all laptops -- it might not turn off your 2832 backlight at all, or it might print a lot of errors to the console, 2833 especially if you are using gpm. 2834 2835config APM_ALLOW_INTS 2836 bool "Allow interrupts during APM BIOS calls" 2837 help 2838 Normally we disable external interrupts while we are making calls to 2839 the APM BIOS as a measure to lessen the effects of a badly behaving 2840 BIOS implementation. The BIOS should reenable interrupts if it 2841 needs to. Unfortunately, some BIOSes do not -- especially those in 2842 many of the newer IBM Thinkpads. If you experience hangs when you 2843 suspend, try setting this to Y. Otherwise, say N. 2844 2845endif # APM 2846 2847source "drivers/cpufreq/Kconfig" 2848 2849source "drivers/cpuidle/Kconfig" 2850 2851source "drivers/idle/Kconfig" 2852 2853endmenu 2854 2855menu "Bus options (PCI etc.)" 2856 2857choice 2858 prompt "PCI access mode" 2859 depends on X86_32 && PCI 2860 default PCI_GOANY 2861 help 2862 On PCI systems, the BIOS can be used to detect the PCI devices and 2863 determine their configuration. However, some old PCI motherboards 2864 have BIOS bugs and may crash if this is done. Also, some embedded 2865 PCI-based systems don't have any BIOS at all. Linux can also try to 2866 detect the PCI hardware directly without using the BIOS. 2867 2868 With this option, you can specify how Linux should detect the 2869 PCI devices. If you choose "BIOS", the BIOS will be used, 2870 if you choose "Direct", the BIOS won't be used, and if you 2871 choose "MMConfig", then PCI Express MMCONFIG will be used. 2872 If you choose "Any", the kernel will try MMCONFIG, then the 2873 direct access method and falls back to the BIOS if that doesn't 2874 work. If unsure, go with the default, which is "Any". 2875 2876config PCI_GOBIOS 2877 bool "BIOS" 2878 2879config PCI_GOMMCONFIG 2880 bool "MMConfig" 2881 2882config PCI_GODIRECT 2883 bool "Direct" 2884 2885config PCI_GOOLPC 2886 bool "OLPC XO-1" 2887 depends on OLPC 2888 2889config PCI_GOANY 2890 bool "Any" 2891 2892endchoice 2893 2894config PCI_BIOS 2895 def_bool y 2896 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2897 2898# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2899config PCI_DIRECT 2900 def_bool y 2901 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2902 2903config PCI_MMCONFIG 2904 bool "Support mmconfig PCI config space access" if X86_64 2905 default y 2906 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2907 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2908 help 2909 Add support for accessing the PCI configuration space as a memory 2910 mapped area. It is the recommended method if the system supports 2911 this (it must have PCI Express and ACPI for it to be available). 2912 2913 In the unlikely case that enabling this configuration option causes 2914 problems, the mechanism can be switched off with the 'pci=nommconf' 2915 command line parameter. 2916 2917 Say N only if you are sure that your platform does not support this 2918 access method or you have problems caused by it. 2919 2920 Say Y otherwise. 2921 2922config PCI_OLPC 2923 def_bool y 2924 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2925 2926config PCI_XEN 2927 def_bool y 2928 depends on PCI && XEN 2929 2930config MMCONF_FAM10H 2931 def_bool y 2932 depends on X86_64 && PCI_MMCONFIG && ACPI 2933 2934config PCI_CNB20LE_QUIRK 2935 bool "Read PCI host bridge windows from the CNB20LE chipset" if EXPERT 2936 depends on X86_32 && PCI 2937 help 2938 Read the PCI windows out of the CNB20LE host bridge. This allows 2939 PCI hotplug to work on systems with the CNB20LE chipset which do 2940 not have ACPI. 2941 2942 The ServerWorks (later Broadcom) CNB20LE was a chipset designed 2943 most probably only for Pentium III. 2944 2945 To find out if you have such a chipset, search for a PCI device with 2946 1166:0009 PCI IDs, for example by executing 2947 lspci -nn | grep '1166:0009' 2948 The code is inactive if there is none. 2949 2950 There's no public spec for this chipset, and this functionality 2951 is known to be incomplete. 2952 2953 You should say N unless you know you need this. 2954 2955config ISA_BUS 2956 bool "ISA bus support on modern systems" if EXPERT 2957 help 2958 Expose ISA bus device drivers and options available for selection and 2959 configuration. Enable this option if your target machine has an ISA 2960 bus. ISA is an older system, displaced by PCI and newer bus 2961 architectures -- if your target machine is modern, it probably does 2962 not have an ISA bus. 2963 2964 If unsure, say N. 2965 2966# x86_64 have no ISA slots, but can have ISA-style DMA. 2967config ISA_DMA_API 2968 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2969 default y 2970 help 2971 Enables ISA-style DMA support for devices requiring such controllers. 2972 If unsure, say Y. 2973 2974if X86_32 2975 2976config ISA 2977 bool "ISA support" 2978 help 2979 Find out whether you have ISA slots on your motherboard. ISA is the 2980 name of a bus system, i.e. the way the CPU talks to the other stuff 2981 inside your box. Other bus systems are PCI, EISA, MicroChannel 2982 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2983 newer boards don't support it. If you have ISA, say Y, otherwise N. 2984 2985config SCx200 2986 tristate "NatSemi SCx200 support" 2987 help 2988 This provides basic support for National Semiconductor's 2989 (now AMD's) Geode processors. The driver probes for the 2990 PCI-IDs of several on-chip devices, so its a good dependency 2991 for other scx200_* drivers. 2992 2993 If compiled as a module, the driver is named scx200. 2994 2995config SCx200HR_TIMER 2996 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2997 depends on SCx200 2998 default y 2999 help 3000 This driver provides a clocksource built upon the on-chip 3001 27MHz high-resolution timer. Its also a workaround for 3002 NSC Geode SC-1100's buggy TSC, which loses time when the 3003 processor goes idle (as is done by the scheduler). The 3004 other workaround is idle=poll boot option. 3005 3006config OLPC 3007 bool "One Laptop Per Child support" 3008 depends on !X86_PAE 3009 select GPIOLIB 3010 select OF 3011 select OF_PROMTREE 3012 select IRQ_DOMAIN 3013 select OLPC_EC 3014 help 3015 Add support for detecting the unique features of the OLPC 3016 XO hardware. 3017 3018config OLPC_XO1_PM 3019 bool "OLPC XO-1 Power Management" 3020 depends on OLPC && MFD_CS5535=y && PM_SLEEP 3021 help 3022 Add support for poweroff and suspend of the OLPC XO-1 laptop. 3023 3024config OLPC_XO1_RTC 3025 bool "OLPC XO-1 Real Time Clock" 3026 depends on OLPC_XO1_PM && RTC_DRV_CMOS 3027 help 3028 Add support for the XO-1 real time clock, which can be used as a 3029 programmable wakeup source. 3030 3031config OLPC_XO1_SCI 3032 bool "OLPC XO-1 SCI extras" 3033 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 3034 depends on INPUT=y 3035 select POWER_SUPPLY 3036 help 3037 Add support for SCI-based features of the OLPC XO-1 laptop: 3038 - EC-driven system wakeups 3039 - Power button 3040 - Ebook switch 3041 - Lid switch 3042 - AC adapter status updates 3043 - Battery status updates 3044 3045config OLPC_XO15_SCI 3046 bool "OLPC XO-1.5 SCI extras" 3047 depends on OLPC && ACPI 3048 select POWER_SUPPLY 3049 help 3050 Add support for SCI-based features of the OLPC XO-1.5 laptop: 3051 - EC-driven system wakeups 3052 - AC adapter status updates 3053 - Battery status updates 3054 3055config GEODE_COMMON 3056 bool 3057 3058config ALIX 3059 bool "PCEngines ALIX System Support (LED setup)" 3060 select GPIOLIB 3061 select GEODE_COMMON 3062 help 3063 This option enables system support for the PCEngines ALIX. 3064 At present this just sets up LEDs for GPIO control on 3065 ALIX2/3/6 boards. However, other system specific setup should 3066 get added here. 3067 3068 Note: You must still enable the drivers for GPIO and LED support 3069 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 3070 3071 Note: You have to set alix.force=1 for boards with Award BIOS. 3072 3073config NET5501 3074 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3075 select GPIOLIB 3076 select GEODE_COMMON 3077 help 3078 This option enables system support for the Soekris Engineering net5501. 3079 3080config GEOS 3081 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3082 select GPIOLIB 3083 select GEODE_COMMON 3084 depends on DMI 3085 help 3086 This option enables system support for the Traverse Technologies GEOS. 3087 3088config TS5500 3089 bool "Technologic Systems TS-5500 platform support" 3090 depends on MELAN 3091 select CHECK_SIGNATURE 3092 select NEW_LEDS 3093 select LEDS_CLASS 3094 help 3095 This option enables system support for the Technologic Systems TS-5500. 3096 3097endif # X86_32 3098 3099config AMD_NB 3100 def_bool y 3101 depends on AMD_NODE 3102 3103config AMD_NODE 3104 def_bool y 3105 depends on CPU_SUP_AMD && PCI 3106 3107endmenu 3108 3109menu "Binary Emulations" 3110 3111config IA32_EMULATION 3112 bool "IA32 Emulation" 3113 depends on X86_64 3114 select ARCH_WANT_OLD_COMPAT_IPC 3115 select BINFMT_ELF 3116 select COMPAT_OLD_SIGACTION 3117 help 3118 Include code to run legacy 32-bit programs under a 3119 64-bit kernel. You should likely turn this on, unless you're 3120 100% sure that you don't have any 32-bit programs left. 3121 3122config IA32_EMULATION_DEFAULT_DISABLED 3123 bool "IA32 emulation disabled by default" 3124 default n 3125 depends on IA32_EMULATION 3126 help 3127 Make IA32 emulation disabled by default. This prevents loading 32-bit 3128 processes and access to 32-bit syscalls. If unsure, leave it to its 3129 default value. 3130 3131config X86_X32_ABI 3132 bool "x32 ABI for 64-bit mode" 3133 depends on X86_64 3134 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3135 # compressed debug sections to x86_x32 properly: 3136 # https://github.com/ClangBuiltLinux/linux/issues/514 3137 # https://github.com/ClangBuiltLinux/linux/issues/1141 3138 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3139 help 3140 Include code to run binaries for the x32 native 32-bit ABI 3141 for 64-bit processors. An x32 process gets access to the 3142 full 64-bit register file and wide data path while leaving 3143 pointers at 32 bits for smaller memory footprint. 3144 3145config COMPAT_32 3146 def_bool y 3147 depends on IA32_EMULATION || X86_32 3148 select HAVE_UID16 3149 select OLD_SIGSUSPEND3 3150 3151config COMPAT 3152 def_bool y 3153 depends on IA32_EMULATION || X86_X32_ABI 3154 3155config COMPAT_FOR_U64_ALIGNMENT 3156 def_bool y 3157 depends on COMPAT 3158 3159endmenu 3160 3161config HAVE_ATOMIC_IOMAP 3162 def_bool y 3163 depends on X86_32 3164 3165source "arch/x86/kvm/Kconfig" 3166 3167source "arch/x86/Kconfig.cpufeatures" 3168 3169source "arch/x86/Kconfig.assembler" 3170