1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select ARCH_USE_CMPXCHG_LOCKREF 32 select HAVE_ARCH_SOFT_DIRTY 33 select MODULES_USE_ELF_RELA 34 select NEED_DMA_MAP_STATE 35 select SWIOTLB 36 select ARCH_HAS_ELFCORE_COMPAT 37 select ZONE_DMA32 38 39config FORCE_DYNAMIC_FTRACE 40 def_bool y 41 depends on X86_32 42 depends on FUNCTION_TRACER 43 select DYNAMIC_FTRACE 44 help 45 We keep the static function tracing (!DYNAMIC_FTRACE) around 46 in order to test the non static function tracing in the 47 generic code, as other architectures still use it. But we 48 only need to keep it around for x86_64. No need to keep it 49 for x86_32. For x86_32, force DYNAMIC_FTRACE. 50# 51# Arch settings 52# 53# ( Note that options that are marked 'if X86_64' could in principle be 54# ported to 32-bit as well. ) 55# 56config X86 57 def_bool y 58 # 59 # Note: keep this list sorted alphabetically 60 # 61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 63 select ARCH_32BIT_OFF_T if X86_32 64 select ARCH_CLOCKSOURCE_INIT 65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 72 select ARCH_HAS_CACHE_LINE_SIZE 73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 74 select ARCH_HAS_CURRENT_STACK_POINTER 75 select ARCH_HAS_DEBUG_VIRTUAL 76 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 77 select ARCH_HAS_DEVMEM_IS_ALLOWED 78 select ARCH_HAS_EARLY_DEBUG if KGDB 79 select ARCH_HAS_ELF_RANDOMIZE 80 select ARCH_HAS_FAST_MULTIPLIER 81 select ARCH_HAS_FORTIFY_SOURCE 82 select ARCH_HAS_GCOV_PROFILE_ALL 83 select ARCH_HAS_KCOV if X86_64 84 select ARCH_HAS_MEM_ENCRYPT 85 select ARCH_HAS_MEMBARRIER_SYNC_CORE 86 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 87 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 88 select ARCH_HAS_PMEM_API if X86_64 89 select ARCH_HAS_PTE_DEVMAP if X86_64 90 select ARCH_HAS_PTE_SPECIAL 91 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 92 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 93 select ARCH_HAS_COPY_MC if X86_64 94 select ARCH_HAS_SET_MEMORY 95 select ARCH_HAS_SET_DIRECT_MAP 96 select ARCH_HAS_STRICT_KERNEL_RWX 97 select ARCH_HAS_STRICT_MODULE_RWX 98 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 99 select ARCH_HAS_SYSCALL_WRAPPER 100 select ARCH_HAS_UBSAN_SANITIZE_ALL 101 select ARCH_HAS_DEBUG_WX 102 select ARCH_HAS_ZONE_DMA_SET if EXPERT 103 select ARCH_HAVE_NMI_SAFE_CMPXCHG 104 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 105 select ARCH_MIGHT_HAVE_PC_PARPORT 106 select ARCH_MIGHT_HAVE_PC_SERIO 107 select ARCH_STACKWALK 108 select ARCH_SUPPORTS_ACPI 109 select ARCH_SUPPORTS_ATOMIC_RMW 110 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 111 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 112 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 113 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 114 select ARCH_SUPPORTS_CFI_CLANG if X86_64 115 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 116 select ARCH_SUPPORTS_LTO_CLANG 117 select ARCH_SUPPORTS_LTO_CLANG_THIN 118 select ARCH_USE_BUILTIN_BSWAP 119 select ARCH_USE_MEMTEST 120 select ARCH_USE_QUEUED_RWLOCKS 121 select ARCH_USE_QUEUED_SPINLOCKS 122 select ARCH_USE_SYM_ANNOTATIONS 123 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 124 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 125 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 126 select ARCH_WANTS_NO_INSTR 127 select ARCH_WANT_GENERAL_HUGETLB 128 select ARCH_WANT_HUGE_PMD_SHARE 129 select ARCH_WANT_LD_ORPHAN_WARN 130 select ARCH_WANT_OPTIMIZE_VMEMMAP if X86_64 131 select ARCH_WANTS_THP_SWAP if X86_64 132 select ARCH_HAS_PARANOID_L1D_FLUSH 133 select BUILDTIME_TABLE_SORT 134 select CLKEVT_I8253 135 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 136 select CLOCKSOURCE_WATCHDOG 137 # Word-size accesses may read uninitialized data past the trailing \0 138 # in strings and cause false KMSAN reports. 139 select DCACHE_WORD_ACCESS if !KMSAN 140 select DYNAMIC_SIGFRAME 141 select EDAC_ATOMIC_SCRUB 142 select EDAC_SUPPORT 143 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 144 select GENERIC_CLOCKEVENTS_MIN_ADJUST 145 select GENERIC_CMOS_UPDATE 146 select GENERIC_CPU_AUTOPROBE 147 select GENERIC_CPU_VULNERABILITIES 148 select GENERIC_EARLY_IOREMAP 149 select GENERIC_ENTRY 150 select GENERIC_IOMAP 151 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 152 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 153 select GENERIC_IRQ_MIGRATION if SMP 154 select GENERIC_IRQ_PROBE 155 select GENERIC_IRQ_RESERVATION_MODE 156 select GENERIC_IRQ_SHOW 157 select GENERIC_PENDING_IRQ if SMP 158 select GENERIC_PTDUMP 159 select GENERIC_SMP_IDLE_THREAD 160 select GENERIC_TIME_VSYSCALL 161 select GENERIC_GETTIMEOFDAY 162 select GENERIC_VDSO_TIME_NS 163 select GUP_GET_PXX_LOW_HIGH if X86_PAE 164 select HARDIRQS_SW_RESEND 165 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 166 select HAS_IOPORT 167 select HAVE_ACPI_APEI if ACPI 168 select HAVE_ACPI_APEI_NMI if ACPI 169 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 170 select HAVE_ARCH_AUDITSYSCALL 171 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 172 select HAVE_ARCH_HUGE_VMALLOC if X86_64 173 select HAVE_ARCH_JUMP_LABEL 174 select HAVE_ARCH_JUMP_LABEL_RELATIVE 175 select HAVE_ARCH_KASAN if X86_64 176 select HAVE_ARCH_KASAN_VMALLOC if X86_64 177 select HAVE_ARCH_KFENCE 178 select HAVE_ARCH_KMSAN if X86_64 179 select HAVE_ARCH_KGDB 180 select HAVE_ARCH_MMAP_RND_BITS if MMU 181 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 182 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 183 select HAVE_ARCH_PREL32_RELOCATIONS 184 select HAVE_ARCH_SECCOMP_FILTER 185 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 186 select HAVE_ARCH_STACKLEAK 187 select HAVE_ARCH_TRACEHOOK 188 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 189 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 190 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 191 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 192 select HAVE_ARCH_VMAP_STACK if X86_64 193 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 194 select HAVE_ARCH_WITHIN_STACK_FRAMES 195 select HAVE_ASM_MODVERSIONS 196 select HAVE_CMPXCHG_DOUBLE 197 select HAVE_CMPXCHG_LOCAL 198 select HAVE_CONTEXT_TRACKING_USER if X86_64 199 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 200 select HAVE_C_RECORDMCOUNT 201 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 202 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 203 select HAVE_BUILDTIME_MCOUNT_SORT 204 select HAVE_DEBUG_KMEMLEAK 205 select HAVE_DMA_CONTIGUOUS 206 select HAVE_DYNAMIC_FTRACE 207 select HAVE_DYNAMIC_FTRACE_WITH_REGS 208 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 209 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 210 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 211 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 212 select HAVE_EBPF_JIT 213 select HAVE_EFFICIENT_UNALIGNED_ACCESS 214 select HAVE_EISA 215 select HAVE_EXIT_THREAD 216 select HAVE_FAST_GUP 217 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 218 select HAVE_FTRACE_MCOUNT_RECORD 219 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 220 select HAVE_FUNCTION_TRACER 221 select HAVE_GCC_PLUGINS 222 select HAVE_HW_BREAKPOINT 223 select HAVE_IOREMAP_PROT 224 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 225 select HAVE_IRQ_TIME_ACCOUNTING 226 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 227 select HAVE_KERNEL_BZIP2 228 select HAVE_KERNEL_GZIP 229 select HAVE_KERNEL_LZ4 230 select HAVE_KERNEL_LZMA 231 select HAVE_KERNEL_LZO 232 select HAVE_KERNEL_XZ 233 select HAVE_KERNEL_ZSTD 234 select HAVE_KPROBES 235 select HAVE_KPROBES_ON_FTRACE 236 select HAVE_FUNCTION_ERROR_INJECTION 237 select HAVE_KRETPROBES 238 select HAVE_RETHOOK 239 select HAVE_KVM 240 select HAVE_LIVEPATCH if X86_64 241 select HAVE_MIXED_BREAKPOINTS_REGS 242 select HAVE_MOD_ARCH_SPECIFIC 243 select HAVE_MOVE_PMD 244 select HAVE_MOVE_PUD 245 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 246 select HAVE_NMI 247 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 248 select HAVE_OBJTOOL if X86_64 249 select HAVE_OPTPROBES 250 select HAVE_PCSPKR_PLATFORM 251 select HAVE_PERF_EVENTS 252 select HAVE_PERF_EVENTS_NMI 253 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 254 select HAVE_PCI 255 select HAVE_PERF_REGS 256 select HAVE_PERF_USER_STACK_DUMP 257 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 258 select MMU_GATHER_MERGE_VMAS 259 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 260 select HAVE_REGS_AND_STACK_ACCESS_API 261 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 262 select HAVE_FUNCTION_ARG_ACCESS_API 263 select HAVE_SETUP_PER_CPU_AREA 264 select HAVE_SOFTIRQ_ON_OWN_STACK 265 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 266 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 267 select HAVE_STATIC_CALL 268 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 269 select HAVE_PREEMPT_DYNAMIC_CALL 270 select HAVE_RSEQ 271 select HAVE_RUST if X86_64 272 select HAVE_SYSCALL_TRACEPOINTS 273 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 274 select HAVE_UNSTABLE_SCHED_CLOCK 275 select HAVE_USER_RETURN_NOTIFIER 276 select HAVE_GENERIC_VDSO 277 select HOTPLUG_SMT if SMP 278 select IRQ_FORCED_THREADING 279 select NEED_PER_CPU_EMBED_FIRST_CHUNK 280 select NEED_PER_CPU_PAGE_FIRST_CHUNK 281 select NEED_SG_DMA_LENGTH 282 select PCI_DOMAINS if PCI 283 select PCI_LOCKLESS_CONFIG if PCI 284 select PERF_EVENTS 285 select RTC_LIB 286 select RTC_MC146818_LIB 287 select SPARSE_IRQ 288 select SYSCTL_EXCEPTION_TRACE 289 select THREAD_INFO_IN_TASK 290 select TRACE_IRQFLAGS_SUPPORT 291 select TRACE_IRQFLAGS_NMI_SUPPORT 292 select USER_STACKTRACE_SUPPORT 293 select HAVE_ARCH_KCSAN if X86_64 294 select X86_FEATURE_NAMES if PROC_FS 295 select PROC_PID_ARCH_STATUS if PROC_FS 296 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 297 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 298 select FUNCTION_ALIGNMENT_4B 299 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 300 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 301 302config INSTRUCTION_DECODER 303 def_bool y 304 depends on KPROBES || PERF_EVENTS || UPROBES 305 306config OUTPUT_FORMAT 307 string 308 default "elf32-i386" if X86_32 309 default "elf64-x86-64" if X86_64 310 311config LOCKDEP_SUPPORT 312 def_bool y 313 314config STACKTRACE_SUPPORT 315 def_bool y 316 317config MMU 318 def_bool y 319 320config ARCH_MMAP_RND_BITS_MIN 321 default 28 if 64BIT 322 default 8 323 324config ARCH_MMAP_RND_BITS_MAX 325 default 32 if 64BIT 326 default 16 327 328config ARCH_MMAP_RND_COMPAT_BITS_MIN 329 default 8 330 331config ARCH_MMAP_RND_COMPAT_BITS_MAX 332 default 16 333 334config SBUS 335 bool 336 337config GENERIC_ISA_DMA 338 def_bool y 339 depends on ISA_DMA_API 340 341config GENERIC_CSUM 342 bool 343 default y if KMSAN || KASAN 344 345config GENERIC_BUG 346 def_bool y 347 depends on BUG 348 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 349 350config GENERIC_BUG_RELATIVE_POINTERS 351 bool 352 353config ARCH_MAY_HAVE_PC_FDC 354 def_bool y 355 depends on ISA_DMA_API 356 357config GENERIC_CALIBRATE_DELAY 358 def_bool y 359 360config ARCH_HAS_CPU_RELAX 361 def_bool y 362 363config ARCH_HIBERNATION_POSSIBLE 364 def_bool y 365 366config ARCH_SUSPEND_POSSIBLE 367 def_bool y 368 369config AUDIT_ARCH 370 def_bool y if X86_64 371 372config KASAN_SHADOW_OFFSET 373 hex 374 depends on KASAN 375 default 0xdffffc0000000000 376 377config HAVE_INTEL_TXT 378 def_bool y 379 depends on INTEL_IOMMU && ACPI 380 381config X86_32_SMP 382 def_bool y 383 depends on X86_32 && SMP 384 385config X86_64_SMP 386 def_bool y 387 depends on X86_64 && SMP 388 389config ARCH_SUPPORTS_UPROBES 390 def_bool y 391 392config FIX_EARLYCON_MEM 393 def_bool y 394 395config DYNAMIC_PHYSICAL_MASK 396 bool 397 398config PGTABLE_LEVELS 399 int 400 default 5 if X86_5LEVEL 401 default 4 if X86_64 402 default 3 if X86_PAE 403 default 2 404 405config CC_HAS_SANE_STACKPROTECTOR 406 bool 407 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 408 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 409 help 410 We have to make sure stack protector is unconditionally disabled if 411 the compiler produces broken code or if it does not let us control 412 the segment on 32-bit kernels. 413 414menu "Processor type and features" 415 416config SMP 417 bool "Symmetric multi-processing support" 418 help 419 This enables support for systems with more than one CPU. If you have 420 a system with only one CPU, say N. If you have a system with more 421 than one CPU, say Y. 422 423 If you say N here, the kernel will run on uni- and multiprocessor 424 machines, but will use only one CPU of a multiprocessor machine. If 425 you say Y here, the kernel will run on many, but not all, 426 uniprocessor machines. On a uniprocessor machine, the kernel 427 will run faster if you say N here. 428 429 Note that if you say Y here and choose architecture "586" or 430 "Pentium" under "Processor family", the kernel will not work on 486 431 architectures. Similarly, multiprocessor kernels for the "PPro" 432 architecture may not work on all Pentium based boards. 433 434 People using multiprocessor machines who say Y here should also say 435 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 436 Management" code will be disabled if you say Y here. 437 438 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 439 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 440 <http://www.tldp.org/docs.html#howto>. 441 442 If you don't know what to do here, say N. 443 444config X86_FEATURE_NAMES 445 bool "Processor feature human-readable names" if EMBEDDED 446 default y 447 help 448 This option compiles in a table of x86 feature bits and corresponding 449 names. This is required to support /proc/cpuinfo and a few kernel 450 messages. You can disable this to save space, at the expense of 451 making those few kernel messages show numeric feature bits instead. 452 453 If in doubt, say Y. 454 455config X86_X2APIC 456 bool "Support x2apic" 457 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 458 help 459 This enables x2apic support on CPUs that have this feature. 460 461 This allows 32-bit apic IDs (so it can support very large systems), 462 and accesses the local apic via MSRs not via mmio. 463 464 Some Intel systems circa 2022 and later are locked into x2APIC mode 465 and can not fall back to the legacy APIC modes if SGX or TDX are 466 enabled in the BIOS. They will boot with very reduced functionality 467 without enabling this option. 468 469 If you don't know what to do here, say N. 470 471config X86_MPPARSE 472 bool "Enable MPS table" if ACPI 473 default y 474 depends on X86_LOCAL_APIC 475 help 476 For old smp systems that do not have proper acpi support. Newer systems 477 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 478 479config GOLDFISH 480 def_bool y 481 depends on X86_GOLDFISH 482 483config X86_CPU_RESCTRL 484 bool "x86 CPU resource control support" 485 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 486 select KERNFS 487 select PROC_CPU_RESCTRL if PROC_FS 488 help 489 Enable x86 CPU resource control support. 490 491 Provide support for the allocation and monitoring of system resources 492 usage by the CPU. 493 494 Intel calls this Intel Resource Director Technology 495 (Intel(R) RDT). More information about RDT can be found in the 496 Intel x86 Architecture Software Developer Manual. 497 498 AMD calls this AMD Platform Quality of Service (AMD QoS). 499 More information about AMD QoS can be found in the AMD64 Technology 500 Platform Quality of Service Extensions manual. 501 502 Say N if unsure. 503 504if X86_32 505config X86_BIGSMP 506 bool "Support for big SMP systems with more than 8 CPUs" 507 depends on SMP 508 help 509 This option is needed for the systems that have more than 8 CPUs. 510 511config X86_EXTENDED_PLATFORM 512 bool "Support for extended (non-PC) x86 platforms" 513 default y 514 help 515 If you disable this option then the kernel will only support 516 standard PC platforms. (which covers the vast majority of 517 systems out there.) 518 519 If you enable this option then you'll be able to select support 520 for the following (non-PC) 32 bit x86 platforms: 521 Goldfish (Android emulator) 522 AMD Elan 523 RDC R-321x SoC 524 SGI 320/540 (Visual Workstation) 525 STA2X11-based (e.g. Northville) 526 Moorestown MID devices 527 528 If you have one of these systems, or if you want to build a 529 generic distribution kernel, say Y here - otherwise say N. 530endif # X86_32 531 532if X86_64 533config X86_EXTENDED_PLATFORM 534 bool "Support for extended (non-PC) x86 platforms" 535 default y 536 help 537 If you disable this option then the kernel will only support 538 standard PC platforms. (which covers the vast majority of 539 systems out there.) 540 541 If you enable this option then you'll be able to select support 542 for the following (non-PC) 64 bit x86 platforms: 543 Numascale NumaChip 544 ScaleMP vSMP 545 SGI Ultraviolet 546 547 If you have one of these systems, or if you want to build a 548 generic distribution kernel, say Y here - otherwise say N. 549endif # X86_64 550# This is an alphabetically sorted list of 64 bit extended platforms 551# Please maintain the alphabetic order if and when there are additions 552config X86_NUMACHIP 553 bool "Numascale NumaChip" 554 depends on X86_64 555 depends on X86_EXTENDED_PLATFORM 556 depends on NUMA 557 depends on SMP 558 depends on X86_X2APIC 559 depends on PCI_MMCONFIG 560 help 561 Adds support for Numascale NumaChip large-SMP systems. Needed to 562 enable more than ~168 cores. 563 If you don't have one of these, you should say N here. 564 565config X86_VSMP 566 bool "ScaleMP vSMP" 567 select HYPERVISOR_GUEST 568 select PARAVIRT 569 depends on X86_64 && PCI 570 depends on X86_EXTENDED_PLATFORM 571 depends on SMP 572 help 573 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 574 supposed to run on these EM64T-based machines. Only choose this option 575 if you have one of these machines. 576 577config X86_UV 578 bool "SGI Ultraviolet" 579 depends on X86_64 580 depends on X86_EXTENDED_PLATFORM 581 depends on NUMA 582 depends on EFI 583 depends on KEXEC_CORE 584 depends on X86_X2APIC 585 depends on PCI 586 help 587 This option is needed in order to support SGI Ultraviolet systems. 588 If you don't have one of these, you should say N here. 589 590# Following is an alphabetically sorted list of 32 bit extended platforms 591# Please maintain the alphabetic order if and when there are additions 592 593config X86_GOLDFISH 594 bool "Goldfish (Virtual Platform)" 595 depends on X86_EXTENDED_PLATFORM 596 help 597 Enable support for the Goldfish virtual platform used primarily 598 for Android development. Unless you are building for the Android 599 Goldfish emulator say N here. 600 601config X86_INTEL_CE 602 bool "CE4100 TV platform" 603 depends on PCI 604 depends on PCI_GODIRECT 605 depends on X86_IO_APIC 606 depends on X86_32 607 depends on X86_EXTENDED_PLATFORM 608 select X86_REBOOTFIXUPS 609 select OF 610 select OF_EARLY_FLATTREE 611 help 612 Select for the Intel CE media processor (CE4100) SOC. 613 This option compiles in support for the CE4100 SOC for settop 614 boxes and media devices. 615 616config X86_INTEL_MID 617 bool "Intel MID platform support" 618 depends on X86_EXTENDED_PLATFORM 619 depends on X86_PLATFORM_DEVICES 620 depends on PCI 621 depends on X86_64 || (PCI_GOANY && X86_32) 622 depends on X86_IO_APIC 623 select I2C 624 select DW_APB_TIMER 625 select INTEL_SCU_PCI 626 help 627 Select to build a kernel capable of supporting Intel MID (Mobile 628 Internet Device) platform systems which do not have the PCI legacy 629 interfaces. If you are building for a PC class system say N here. 630 631 Intel MID platforms are based on an Intel processor and chipset which 632 consume less power than most of the x86 derivatives. 633 634config X86_INTEL_QUARK 635 bool "Intel Quark platform support" 636 depends on X86_32 637 depends on X86_EXTENDED_PLATFORM 638 depends on X86_PLATFORM_DEVICES 639 depends on X86_TSC 640 depends on PCI 641 depends on PCI_GOANY 642 depends on X86_IO_APIC 643 select IOSF_MBI 644 select INTEL_IMR 645 select COMMON_CLK 646 help 647 Select to include support for Quark X1000 SoC. 648 Say Y here if you have a Quark based system such as the Arduino 649 compatible Intel Galileo. 650 651config X86_INTEL_LPSS 652 bool "Intel Low Power Subsystem Support" 653 depends on X86 && ACPI && PCI 654 select COMMON_CLK 655 select PINCTRL 656 select IOSF_MBI 657 help 658 Select to build support for Intel Low Power Subsystem such as 659 found on Intel Lynxpoint PCH. Selecting this option enables 660 things like clock tree (common clock framework) and pincontrol 661 which are needed by the LPSS peripheral drivers. 662 663config X86_AMD_PLATFORM_DEVICE 664 bool "AMD ACPI2Platform devices support" 665 depends on ACPI 666 select COMMON_CLK 667 select PINCTRL 668 help 669 Select to interpret AMD specific ACPI device to platform device 670 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 671 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 672 implemented under PINCTRL subsystem. 673 674config IOSF_MBI 675 tristate "Intel SoC IOSF Sideband support for SoC platforms" 676 depends on PCI 677 help 678 This option enables sideband register access support for Intel SoC 679 platforms. On these platforms the IOSF sideband is used in lieu of 680 MSR's for some register accesses, mostly but not limited to thermal 681 and power. Drivers may query the availability of this device to 682 determine if they need the sideband in order to work on these 683 platforms. The sideband is available on the following SoC products. 684 This list is not meant to be exclusive. 685 - BayTrail 686 - Braswell 687 - Quark 688 689 You should say Y if you are running a kernel on one of these SoC's. 690 691config IOSF_MBI_DEBUG 692 bool "Enable IOSF sideband access through debugfs" 693 depends on IOSF_MBI && DEBUG_FS 694 help 695 Select this option to expose the IOSF sideband access registers (MCR, 696 MDR, MCRX) through debugfs to write and read register information from 697 different units on the SoC. This is most useful for obtaining device 698 state information for debug and analysis. As this is a general access 699 mechanism, users of this option would have specific knowledge of the 700 device they want to access. 701 702 If you don't require the option or are in doubt, say N. 703 704config X86_RDC321X 705 bool "RDC R-321x SoC" 706 depends on X86_32 707 depends on X86_EXTENDED_PLATFORM 708 select M486 709 select X86_REBOOTFIXUPS 710 help 711 This option is needed for RDC R-321x system-on-chip, also known 712 as R-8610-(G). 713 If you don't have one of these chips, you should say N here. 714 715config X86_32_NON_STANDARD 716 bool "Support non-standard 32-bit SMP architectures" 717 depends on X86_32 && SMP 718 depends on X86_EXTENDED_PLATFORM 719 help 720 This option compiles in the bigsmp and STA2X11 default 721 subarchitectures. It is intended for a generic binary 722 kernel. If you select them all, kernel will probe it one by 723 one and will fallback to default. 724 725# Alphabetically sorted list of Non standard 32 bit platforms 726 727config X86_SUPPORTS_MEMORY_FAILURE 728 def_bool y 729 # MCE code calls memory_failure(): 730 depends on X86_MCE 731 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 732 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 733 depends on X86_64 || !SPARSEMEM 734 select ARCH_SUPPORTS_MEMORY_FAILURE 735 736config STA2X11 737 bool "STA2X11 Companion Chip Support" 738 depends on X86_32_NON_STANDARD && PCI 739 select SWIOTLB 740 select MFD_STA2X11 741 select GPIOLIB 742 help 743 This adds support for boards based on the STA2X11 IO-Hub, 744 a.k.a. "ConneXt". The chip is used in place of the standard 745 PC chipset, so all "standard" peripherals are missing. If this 746 option is selected the kernel will still be able to boot on 747 standard PC machines. 748 749config X86_32_IRIS 750 tristate "Eurobraille/Iris poweroff module" 751 depends on X86_32 752 help 753 The Iris machines from EuroBraille do not have APM or ACPI support 754 to shut themselves down properly. A special I/O sequence is 755 needed to do so, which is what this module does at 756 kernel shutdown. 757 758 This is only for Iris machines from EuroBraille. 759 760 If unused, say N. 761 762config SCHED_OMIT_FRAME_POINTER 763 def_bool y 764 prompt "Single-depth WCHAN output" 765 depends on X86 766 help 767 Calculate simpler /proc/<PID>/wchan values. If this option 768 is disabled then wchan values will recurse back to the 769 caller function. This provides more accurate wchan values, 770 at the expense of slightly more scheduling overhead. 771 772 If in doubt, say "Y". 773 774menuconfig HYPERVISOR_GUEST 775 bool "Linux guest support" 776 help 777 Say Y here to enable options for running Linux under various hyper- 778 visors. This option enables basic hypervisor detection and platform 779 setup. 780 781 If you say N, all options in this submenu will be skipped and 782 disabled, and Linux guest support won't be built in. 783 784if HYPERVISOR_GUEST 785 786config PARAVIRT 787 bool "Enable paravirtualization code" 788 depends on HAVE_STATIC_CALL 789 help 790 This changes the kernel so it can modify itself when it is run 791 under a hypervisor, potentially improving performance significantly 792 over full virtualization. However, when run without a hypervisor 793 the kernel is theoretically slower and slightly larger. 794 795config PARAVIRT_XXL 796 bool 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 select ARCH_HAS_CC_PLATFORM 888 select X86_MEM_ENCRYPT 889 select X86_MCE 890 help 891 Support running as a guest under Intel TDX. Without this support, 892 the guest kernel can not boot or run under TDX. 893 TDX includes memory encryption and integrity capabilities 894 which protect the confidentiality and integrity of guest 895 memory contents and CPU state. TDX guests are protected from 896 some attacks from the VMM. 897 898endif # HYPERVISOR_GUEST 899 900source "arch/x86/Kconfig.cpu" 901 902config HPET_TIMER 903 def_bool X86_64 904 prompt "HPET Timer Support" if X86_32 905 help 906 Use the IA-PC HPET (High Precision Event Timer) to manage 907 time in preference to the PIT and RTC, if a HPET is 908 present. 909 HPET is the next generation timer replacing legacy 8254s. 910 The HPET provides a stable time base on SMP 911 systems, unlike the TSC, but it is more expensive to access, 912 as it is off-chip. The interface used is documented 913 in the HPET spec, revision 1. 914 915 You can safely choose Y here. However, HPET will only be 916 activated if the platform and the BIOS support this feature. 917 Otherwise the 8254 will be used for timing services. 918 919 Choose N to continue using the legacy 8254 timer. 920 921config HPET_EMULATE_RTC 922 def_bool y 923 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 924 925# Mark as expert because too many people got it wrong. 926# The code disables itself when not needed. 927config DMI 928 default y 929 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 930 bool "Enable DMI scanning" if EXPERT 931 help 932 Enabled scanning of DMI to identify machine quirks. Say Y 933 here unless you have verified that your setup is not 934 affected by entries in the DMI blacklist. Required by PNP 935 BIOS code. 936 937config GART_IOMMU 938 bool "Old AMD GART IOMMU support" 939 select DMA_OPS 940 select IOMMU_HELPER 941 select SWIOTLB 942 depends on X86_64 && PCI && AMD_NB 943 help 944 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 945 GART based hardware IOMMUs. 946 947 The GART supports full DMA access for devices with 32-bit access 948 limitations, on systems with more than 3 GB. This is usually needed 949 for USB, sound, many IDE/SATA chipsets and some other devices. 950 951 Newer systems typically have a modern AMD IOMMU, supported via 952 the CONFIG_AMD_IOMMU=y config option. 953 954 In normal configurations this driver is only active when needed: 955 there's more than 3 GB of memory and the system contains a 956 32-bit limited device. 957 958 If unsure, say Y. 959 960config BOOT_VESA_SUPPORT 961 bool 962 help 963 If true, at least one selected framebuffer driver can take advantage 964 of VESA video modes set at an early boot stage via the vga= parameter. 965 966config MAXSMP 967 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 968 depends on X86_64 && SMP && DEBUG_KERNEL 969 select CPUMASK_OFFSTACK 970 help 971 Enable maximum number of CPUS and NUMA Nodes for this architecture. 972 If unsure, say N. 973 974# 975# The maximum number of CPUs supported: 976# 977# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 978# and which can be configured interactively in the 979# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 980# 981# The ranges are different on 32-bit and 64-bit kernels, depending on 982# hardware capabilities and scalability features of the kernel. 983# 984# ( If MAXSMP is enabled we just use the highest possible value and disable 985# interactive configuration. ) 986# 987 988config NR_CPUS_RANGE_BEGIN 989 int 990 default NR_CPUS_RANGE_END if MAXSMP 991 default 1 if !SMP 992 default 2 993 994config NR_CPUS_RANGE_END 995 int 996 depends on X86_32 997 default 64 if SMP && X86_BIGSMP 998 default 8 if SMP && !X86_BIGSMP 999 default 1 if !SMP 1000 1001config NR_CPUS_RANGE_END 1002 int 1003 depends on X86_64 1004 default 8192 if SMP && CPUMASK_OFFSTACK 1005 default 512 if SMP && !CPUMASK_OFFSTACK 1006 default 1 if !SMP 1007 1008config NR_CPUS_DEFAULT 1009 int 1010 depends on X86_32 1011 default 32 if X86_BIGSMP 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 && CPU_SUP_INTEL 1061 select X86_INTEL_PSTATE 1062 select CPU_FREQ 1063 default y 1064 help 1065 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1066 core ordering determined at manufacturing time, which allows 1067 certain cores to reach higher turbo frequencies (when running 1068 single threaded workloads) than others. 1069 1070 Enabling this kernel feature teaches the scheduler about 1071 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1072 scheduler's CPU selection logic accordingly, so that higher 1073 overall system performance can be achieved. 1074 1075 This feature will have no effect on CPUs without this feature. 1076 1077 If unsure say Y here. 1078 1079config UP_LATE_INIT 1080 def_bool y 1081 depends on !SMP && X86_LOCAL_APIC 1082 1083config X86_UP_APIC 1084 bool "Local APIC support on uniprocessors" if !PCI_MSI 1085 default PCI_MSI 1086 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1087 help 1088 A local APIC (Advanced Programmable Interrupt Controller) is an 1089 integrated interrupt controller in the CPU. If you have a single-CPU 1090 system which has a processor with a local APIC, you can say Y here to 1091 enable and use it. If you say Y here even though your machine doesn't 1092 have a local APIC, then the kernel will still run with no slowdown at 1093 all. The local APIC supports CPU-generated self-interrupts (timer, 1094 performance counters), and the NMI watchdog which detects hard 1095 lockups. 1096 1097config X86_UP_IOAPIC 1098 bool "IO-APIC support on uniprocessors" 1099 depends on X86_UP_APIC 1100 help 1101 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1102 SMP-capable replacement for PC-style interrupt controllers. Most 1103 SMP systems and many recent uniprocessor systems have one. 1104 1105 If you have a single-CPU system with an IO-APIC, you can say Y here 1106 to use it. If you say Y here even though your machine doesn't have 1107 an IO-APIC, then the kernel will still run with no slowdown at all. 1108 1109config X86_LOCAL_APIC 1110 def_bool y 1111 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1112 select IRQ_DOMAIN_HIERARCHY 1113 1114config X86_IO_APIC 1115 def_bool y 1116 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1117 1118config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1119 bool "Reroute for broken boot IRQs" 1120 depends on X86_IO_APIC 1121 help 1122 This option enables a workaround that fixes a source of 1123 spurious interrupts. This is recommended when threaded 1124 interrupt handling is used on systems where the generation of 1125 superfluous "boot interrupts" cannot be disabled. 1126 1127 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1128 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1129 kernel does during interrupt handling). On chipsets where this 1130 boot IRQ generation cannot be disabled, this workaround keeps 1131 the original IRQ line masked so that only the equivalent "boot 1132 IRQ" is delivered to the CPUs. The workaround also tells the 1133 kernel to set up the IRQ handler on the boot IRQ line. In this 1134 way only one interrupt is delivered to the kernel. Otherwise 1135 the spurious second interrupt may cause the kernel to bring 1136 down (vital) interrupt lines. 1137 1138 Only affects "broken" chipsets. Interrupt sharing may be 1139 increased on these systems. 1140 1141config X86_MCE 1142 bool "Machine Check / overheating reporting" 1143 select GENERIC_ALLOCATOR 1144 default y 1145 help 1146 Machine Check support allows the processor to notify the 1147 kernel if it detects a problem (e.g. overheating, data corruption). 1148 The action the kernel takes depends on the severity of the problem, 1149 ranging from warning messages to halting the machine. 1150 1151config X86_MCELOG_LEGACY 1152 bool "Support for deprecated /dev/mcelog character device" 1153 depends on X86_MCE 1154 help 1155 Enable support for /dev/mcelog which is needed by the old mcelog 1156 userspace logging daemon. Consider switching to the new generation 1157 rasdaemon solution. 1158 1159config X86_MCE_INTEL 1160 def_bool y 1161 prompt "Intel MCE features" 1162 depends on X86_MCE && X86_LOCAL_APIC 1163 help 1164 Additional support for intel specific MCE features such as 1165 the thermal monitor. 1166 1167config X86_MCE_AMD 1168 def_bool y 1169 prompt "AMD MCE features" 1170 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1171 help 1172 Additional support for AMD specific MCE features such as 1173 the DRAM Error Threshold. 1174 1175config X86_ANCIENT_MCE 1176 bool "Support for old Pentium 5 / WinChip machine checks" 1177 depends on X86_32 && X86_MCE 1178 help 1179 Include support for machine check handling on old Pentium 5 or WinChip 1180 systems. These typically need to be enabled explicitly on the command 1181 line. 1182 1183config X86_MCE_THRESHOLD 1184 depends on X86_MCE_AMD || X86_MCE_INTEL 1185 def_bool y 1186 1187config X86_MCE_INJECT 1188 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1189 tristate "Machine check injector support" 1190 help 1191 Provide support for injecting machine checks for testing purposes. 1192 If you don't know what a machine check is and you don't do kernel 1193 QA it is safe to say n. 1194 1195source "arch/x86/events/Kconfig" 1196 1197config X86_LEGACY_VM86 1198 bool "Legacy VM86 support" 1199 depends on X86_32 1200 help 1201 This option allows user programs to put the CPU into V8086 1202 mode, which is an 80286-era approximation of 16-bit real mode. 1203 1204 Some very old versions of X and/or vbetool require this option 1205 for user mode setting. Similarly, DOSEMU will use it if 1206 available to accelerate real mode DOS programs. However, any 1207 recent version of DOSEMU, X, or vbetool should be fully 1208 functional even without kernel VM86 support, as they will all 1209 fall back to software emulation. Nevertheless, if you are using 1210 a 16-bit DOS program where 16-bit performance matters, vm86 1211 mode might be faster than emulation and you might want to 1212 enable this option. 1213 1214 Note that any app that works on a 64-bit kernel is unlikely to 1215 need this option, as 64-bit kernels don't, and can't, support 1216 V8086 mode. This option is also unrelated to 16-bit protected 1217 mode and is not needed to run most 16-bit programs under Wine. 1218 1219 Enabling this option increases the complexity of the kernel 1220 and slows down exception handling a tiny bit. 1221 1222 If unsure, say N here. 1223 1224config VM86 1225 bool 1226 default X86_LEGACY_VM86 1227 1228config X86_16BIT 1229 bool "Enable support for 16-bit segments" if EXPERT 1230 default y 1231 depends on MODIFY_LDT_SYSCALL 1232 help 1233 This option is required by programs like Wine to run 16-bit 1234 protected mode legacy code on x86 processors. Disabling 1235 this option saves about 300 bytes on i386, or around 6K text 1236 plus 16K runtime memory on x86-64, 1237 1238config X86_ESPFIX32 1239 def_bool y 1240 depends on X86_16BIT && X86_32 1241 1242config X86_ESPFIX64 1243 def_bool y 1244 depends on X86_16BIT && X86_64 1245 1246config X86_VSYSCALL_EMULATION 1247 bool "Enable vsyscall emulation" if EXPERT 1248 default y 1249 depends on X86_64 1250 help 1251 This enables emulation of the legacy vsyscall page. Disabling 1252 it is roughly equivalent to booting with vsyscall=none, except 1253 that it will also disable the helpful warning if a program 1254 tries to use a vsyscall. With this option set to N, offending 1255 programs will just segfault, citing addresses of the form 1256 0xffffffffff600?00. 1257 1258 This option is required by many programs built before 2013, and 1259 care should be used even with newer programs if set to N. 1260 1261 Disabling this option saves about 7K of kernel size and 1262 possibly 4K of additional runtime pagetable memory. 1263 1264config X86_IOPL_IOPERM 1265 bool "IOPERM and IOPL Emulation" 1266 default y 1267 help 1268 This enables the ioperm() and iopl() syscalls which are necessary 1269 for legacy applications. 1270 1271 Legacy IOPL support is an overbroad mechanism which allows user 1272 space aside of accessing all 65536 I/O ports also to disable 1273 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1274 capabilities and permission from potentially active security 1275 modules. 1276 1277 The emulation restricts the functionality of the syscall to 1278 only allowing the full range I/O port access, but prevents the 1279 ability to disable interrupts from user space which would be 1280 granted if the hardware IOPL mechanism would be used. 1281 1282config TOSHIBA 1283 tristate "Toshiba Laptop support" 1284 depends on X86_32 1285 help 1286 This adds a driver to safely access the System Management Mode of 1287 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1288 not work on models with a Phoenix BIOS. The System Management Mode 1289 is used to set the BIOS and power saving options on Toshiba portables. 1290 1291 For information on utilities to make use of this driver see the 1292 Toshiba Linux utilities web site at: 1293 <http://www.buzzard.org.uk/toshiba/>. 1294 1295 Say Y if you intend to run this kernel on a Toshiba portable. 1296 Say N otherwise. 1297 1298config X86_REBOOTFIXUPS 1299 bool "Enable X86 board specific fixups for reboot" 1300 depends on X86_32 1301 help 1302 This enables chipset and/or board specific fixups to be done 1303 in order to get reboot to work correctly. This is only needed on 1304 some combinations of hardware and BIOS. The symptom, for which 1305 this config is intended, is when reboot ends with a stalled/hung 1306 system. 1307 1308 Currently, the only fixup is for the Geode machines using 1309 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1310 1311 Say Y if you want to enable the fixup. Currently, it's safe to 1312 enable this option even if you don't need it. 1313 Say N otherwise. 1314 1315config MICROCODE 1316 bool "CPU microcode loading support" 1317 default y 1318 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1319 help 1320 If you say Y here, you will be able to update the microcode on 1321 Intel and AMD processors. The Intel support is for the IA32 family, 1322 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1323 AMD support is for families 0x10 and later. You will obviously need 1324 the actual microcode binary data itself which is not shipped with 1325 the Linux kernel. 1326 1327 The preferred method to load microcode from a detached initrd is described 1328 in Documentation/arch/x86/microcode.rst. For that you need to enable 1329 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1330 initrd for microcode blobs. 1331 1332 In addition, you can build the microcode into the kernel. For that you 1333 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1334 config option. 1335 1336config MICROCODE_INTEL 1337 bool "Intel microcode loading support" 1338 depends on CPU_SUP_INTEL && MICROCODE 1339 default MICROCODE 1340 help 1341 This options enables microcode patch loading support for Intel 1342 processors. 1343 1344 For the current Intel microcode data package go to 1345 <https://downloadcenter.intel.com> and search for 1346 'Linux Processor Microcode Data File'. 1347 1348config MICROCODE_AMD 1349 bool "AMD microcode loading support" 1350 depends on CPU_SUP_AMD && MICROCODE 1351 help 1352 If you select this option, microcode patch loading support for AMD 1353 processors will be enabled. 1354 1355config MICROCODE_LATE_LOADING 1356 bool "Late microcode loading (DANGEROUS)" 1357 default n 1358 depends on MICROCODE 1359 help 1360 Loading microcode late, when the system is up and executing instructions 1361 is a tricky business and should be avoided if possible. Just the sequence 1362 of synchronizing all cores and SMT threads is one fragile dance which does 1363 not guarantee that cores might not softlock after the loading. Therefore, 1364 use this at your own risk. Late loading taints the kernel too. 1365 1366config X86_MSR 1367 tristate "/dev/cpu/*/msr - Model-specific register support" 1368 help 1369 This device gives privileged processes access to the x86 1370 Model-Specific Registers (MSRs). It is a character device with 1371 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1372 MSR accesses are directed to a specific CPU on multi-processor 1373 systems. 1374 1375config X86_CPUID 1376 tristate "/dev/cpu/*/cpuid - CPU information support" 1377 help 1378 This device gives processes access to the x86 CPUID instruction to 1379 be executed on a specific processor. It is a character device 1380 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1381 /dev/cpu/31/cpuid. 1382 1383choice 1384 prompt "High Memory Support" 1385 default HIGHMEM4G 1386 depends on X86_32 1387 1388config NOHIGHMEM 1389 bool "off" 1390 help 1391 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1392 However, the address space of 32-bit x86 processors is only 4 1393 Gigabytes large. That means that, if you have a large amount of 1394 physical memory, not all of it can be "permanently mapped" by the 1395 kernel. The physical memory that's not permanently mapped is called 1396 "high memory". 1397 1398 If you are compiling a kernel which will never run on a machine with 1399 more than 1 Gigabyte total physical RAM, answer "off" here (default 1400 choice and suitable for most users). This will result in a "3GB/1GB" 1401 split: 3GB are mapped so that each process sees a 3GB virtual memory 1402 space and the remaining part of the 4GB virtual memory space is used 1403 by the kernel to permanently map as much physical memory as 1404 possible. 1405 1406 If the machine has between 1 and 4 Gigabytes physical RAM, then 1407 answer "4GB" here. 1408 1409 If more than 4 Gigabytes is used then answer "64GB" here. This 1410 selection turns Intel PAE (Physical Address Extension) mode on. 1411 PAE implements 3-level paging on IA32 processors. PAE is fully 1412 supported by Linux, PAE mode is implemented on all recent Intel 1413 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1414 then the kernel will not boot on CPUs that don't support PAE! 1415 1416 The actual amount of total physical memory will either be 1417 auto detected or can be forced by using a kernel command line option 1418 such as "mem=256M". (Try "man bootparam" or see the documentation of 1419 your boot loader (lilo or loadlin) about how to pass options to the 1420 kernel at boot time.) 1421 1422 If unsure, say "off". 1423 1424config HIGHMEM4G 1425 bool "4GB" 1426 help 1427 Select this if you have a 32-bit processor and between 1 and 4 1428 gigabytes of physical RAM. 1429 1430config HIGHMEM64G 1431 bool "64GB" 1432 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1433 select X86_PAE 1434 help 1435 Select this if you have a 32-bit processor and more than 4 1436 gigabytes of physical RAM. 1437 1438endchoice 1439 1440choice 1441 prompt "Memory split" if EXPERT 1442 default VMSPLIT_3G 1443 depends on X86_32 1444 help 1445 Select the desired split between kernel and user memory. 1446 1447 If the address range available to the kernel is less than the 1448 physical memory installed, the remaining memory will be available 1449 as "high memory". Accessing high memory is a little more costly 1450 than low memory, as it needs to be mapped into the kernel first. 1451 Note that increasing the kernel address space limits the range 1452 available to user programs, making the address space there 1453 tighter. Selecting anything other than the default 3G/1G split 1454 will also likely make your kernel incompatible with binary-only 1455 kernel modules. 1456 1457 If you are not absolutely sure what you are doing, leave this 1458 option alone! 1459 1460 config VMSPLIT_3G 1461 bool "3G/1G user/kernel split" 1462 config VMSPLIT_3G_OPT 1463 depends on !X86_PAE 1464 bool "3G/1G user/kernel split (for full 1G low memory)" 1465 config VMSPLIT_2G 1466 bool "2G/2G user/kernel split" 1467 config VMSPLIT_2G_OPT 1468 depends on !X86_PAE 1469 bool "2G/2G user/kernel split (for full 2G low memory)" 1470 config VMSPLIT_1G 1471 bool "1G/3G user/kernel split" 1472endchoice 1473 1474config PAGE_OFFSET 1475 hex 1476 default 0xB0000000 if VMSPLIT_3G_OPT 1477 default 0x80000000 if VMSPLIT_2G 1478 default 0x78000000 if VMSPLIT_2G_OPT 1479 default 0x40000000 if VMSPLIT_1G 1480 default 0xC0000000 1481 depends on X86_32 1482 1483config HIGHMEM 1484 def_bool y 1485 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1486 1487config X86_PAE 1488 bool "PAE (Physical Address Extension) Support" 1489 depends on X86_32 && !HIGHMEM4G 1490 select PHYS_ADDR_T_64BIT 1491 select SWIOTLB 1492 help 1493 PAE is required for NX support, and furthermore enables 1494 larger swapspace support for non-overcommit purposes. It 1495 has the cost of more pagetable lookup overhead, and also 1496 consumes more pagetable space per process. 1497 1498config X86_5LEVEL 1499 bool "Enable 5-level page tables support" 1500 default y 1501 select DYNAMIC_MEMORY_LAYOUT 1502 select SPARSEMEM_VMEMMAP 1503 depends on X86_64 1504 help 1505 5-level paging enables access to larger address space: 1506 up to 128 PiB of virtual address space and 4 PiB of 1507 physical address space. 1508 1509 It will be supported by future Intel CPUs. 1510 1511 A kernel with the option enabled can be booted on machines that 1512 support 4- or 5-level paging. 1513 1514 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1515 information. 1516 1517 Say N if unsure. 1518 1519config X86_DIRECT_GBPAGES 1520 def_bool y 1521 depends on X86_64 1522 help 1523 Certain kernel features effectively disable kernel 1524 linear 1 GB mappings (even if the CPU otherwise 1525 supports them), so don't confuse the user by printing 1526 that we have them enabled. 1527 1528config X86_CPA_STATISTICS 1529 bool "Enable statistic for Change Page Attribute" 1530 depends on DEBUG_FS 1531 help 1532 Expose statistics about the Change Page Attribute mechanism, which 1533 helps to determine the effectiveness of preserving large and huge 1534 page mappings when mapping protections are changed. 1535 1536config X86_MEM_ENCRYPT 1537 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1538 select DYNAMIC_PHYSICAL_MASK 1539 def_bool n 1540 1541config AMD_MEM_ENCRYPT 1542 bool "AMD Secure Memory Encryption (SME) support" 1543 depends on X86_64 && CPU_SUP_AMD 1544 select DMA_COHERENT_POOL 1545 select ARCH_USE_MEMREMAP_PROT 1546 select INSTRUCTION_DECODER 1547 select ARCH_HAS_CC_PLATFORM 1548 select X86_MEM_ENCRYPT 1549 help 1550 Say yes to enable support for the encryption of system memory. 1551 This requires an AMD processor that supports Secure Memory 1552 Encryption (SME). 1553 1554config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1555 bool "Activate AMD Secure Memory Encryption (SME) by default" 1556 depends on AMD_MEM_ENCRYPT 1557 help 1558 Say yes to have system memory encrypted by default if running on 1559 an AMD processor that supports Secure Memory Encryption (SME). 1560 1561 If set to Y, then the encryption of system memory can be 1562 deactivated with the mem_encrypt=off command line option. 1563 1564 If set to N, then the encryption of system memory can be 1565 activated with the mem_encrypt=on command line option. 1566 1567# Common NUMA Features 1568config NUMA 1569 bool "NUMA Memory Allocation and Scheduler Support" 1570 depends on SMP 1571 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1572 default y if X86_BIGSMP 1573 select USE_PERCPU_NUMA_NODE_ID 1574 help 1575 Enable NUMA (Non-Uniform Memory Access) support. 1576 1577 The kernel will try to allocate memory used by a CPU on the 1578 local memory controller of the CPU and add some more 1579 NUMA awareness to the kernel. 1580 1581 For 64-bit this is recommended if the system is Intel Core i7 1582 (or later), AMD Opteron, or EM64T NUMA. 1583 1584 For 32-bit this is only needed if you boot a 32-bit 1585 kernel on a 64-bit NUMA platform. 1586 1587 Otherwise, you should say N. 1588 1589config AMD_NUMA 1590 def_bool y 1591 prompt "Old style AMD Opteron NUMA detection" 1592 depends on X86_64 && NUMA && PCI 1593 help 1594 Enable AMD NUMA node topology detection. You should say Y here if 1595 you have a multi processor AMD system. This uses an old method to 1596 read the NUMA configuration directly from the builtin Northbridge 1597 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1598 which also takes priority if both are compiled in. 1599 1600config X86_64_ACPI_NUMA 1601 def_bool y 1602 prompt "ACPI NUMA detection" 1603 depends on X86_64 && NUMA && ACPI && PCI 1604 select ACPI_NUMA 1605 help 1606 Enable ACPI SRAT based node topology detection. 1607 1608config NUMA_EMU 1609 bool "NUMA emulation" 1610 depends on NUMA 1611 help 1612 Enable NUMA emulation. A flat machine will be split 1613 into virtual nodes when booted with "numa=fake=N", where N is the 1614 number of nodes. This is only useful for debugging. 1615 1616config NODES_SHIFT 1617 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1618 range 1 10 1619 default "10" if MAXSMP 1620 default "6" if X86_64 1621 default "3" 1622 depends on NUMA 1623 help 1624 Specify the maximum number of NUMA Nodes available on the target 1625 system. Increases memory reserved to accommodate various tables. 1626 1627config ARCH_FLATMEM_ENABLE 1628 def_bool y 1629 depends on X86_32 && !NUMA 1630 1631config ARCH_SPARSEMEM_ENABLE 1632 def_bool y 1633 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1634 select SPARSEMEM_STATIC if X86_32 1635 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1636 1637config ARCH_SPARSEMEM_DEFAULT 1638 def_bool X86_64 || (NUMA && X86_32) 1639 1640config ARCH_SELECT_MEMORY_MODEL 1641 def_bool y 1642 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1643 1644config ARCH_MEMORY_PROBE 1645 bool "Enable sysfs memory/probe interface" 1646 depends on MEMORY_HOTPLUG 1647 help 1648 This option enables a sysfs memory/probe interface for testing. 1649 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1650 If you are unsure how to answer this question, answer N. 1651 1652config ARCH_PROC_KCORE_TEXT 1653 def_bool y 1654 depends on X86_64 && PROC_KCORE 1655 1656config ILLEGAL_POINTER_VALUE 1657 hex 1658 default 0 if X86_32 1659 default 0xdead000000000000 if X86_64 1660 1661config X86_PMEM_LEGACY_DEVICE 1662 bool 1663 1664config X86_PMEM_LEGACY 1665 tristate "Support non-standard NVDIMMs and ADR protected memory" 1666 depends on PHYS_ADDR_T_64BIT 1667 depends on BLK_DEV 1668 select X86_PMEM_LEGACY_DEVICE 1669 select NUMA_KEEP_MEMINFO if NUMA 1670 select LIBNVDIMM 1671 help 1672 Treat memory marked using the non-standard e820 type of 12 as used 1673 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1674 The kernel will offer these regions to the 'pmem' driver so 1675 they can be used for persistent storage. 1676 1677 Say Y if unsure. 1678 1679config HIGHPTE 1680 bool "Allocate 3rd-level pagetables from highmem" 1681 depends on HIGHMEM 1682 help 1683 The VM uses one page table entry for each page of physical memory. 1684 For systems with a lot of RAM, this can be wasteful of precious 1685 low memory. Setting this option will put user-space page table 1686 entries in high memory. 1687 1688config X86_CHECK_BIOS_CORRUPTION 1689 bool "Check for low memory corruption" 1690 help 1691 Periodically check for memory corruption in low memory, which 1692 is suspected to be caused by BIOS. Even when enabled in the 1693 configuration, it is disabled at runtime. Enable it by 1694 setting "memory_corruption_check=1" on the kernel command 1695 line. By default it scans the low 64k of memory every 60 1696 seconds; see the memory_corruption_check_size and 1697 memory_corruption_check_period parameters in 1698 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1699 1700 When enabled with the default parameters, this option has 1701 almost no overhead, as it reserves a relatively small amount 1702 of memory and scans it infrequently. It both detects corruption 1703 and prevents it from affecting the running system. 1704 1705 It is, however, intended as a diagnostic tool; if repeatable 1706 BIOS-originated corruption always affects the same memory, 1707 you can use memmap= to prevent the kernel from using that 1708 memory. 1709 1710config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1711 bool "Set the default setting of memory_corruption_check" 1712 depends on X86_CHECK_BIOS_CORRUPTION 1713 default y 1714 help 1715 Set whether the default state of memory_corruption_check is 1716 on or off. 1717 1718config MATH_EMULATION 1719 bool 1720 depends on MODIFY_LDT_SYSCALL 1721 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1722 help 1723 Linux can emulate a math coprocessor (used for floating point 1724 operations) if you don't have one. 486DX and Pentium processors have 1725 a math coprocessor built in, 486SX and 386 do not, unless you added 1726 a 487DX or 387, respectively. (The messages during boot time can 1727 give you some hints here ["man dmesg"].) Everyone needs either a 1728 coprocessor or this emulation. 1729 1730 If you don't have a math coprocessor, you need to say Y here; if you 1731 say Y here even though you have a coprocessor, the coprocessor will 1732 be used nevertheless. (This behavior can be changed with the kernel 1733 command line option "no387", which comes handy if your coprocessor 1734 is broken. Try "man bootparam" or see the documentation of your boot 1735 loader (lilo or loadlin) about how to pass options to the kernel at 1736 boot time.) This means that it is a good idea to say Y here if you 1737 intend to use this kernel on different machines. 1738 1739 More information about the internals of the Linux math coprocessor 1740 emulation can be found in <file:arch/x86/math-emu/README>. 1741 1742 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1743 kernel, it won't hurt. 1744 1745config MTRR 1746 def_bool y 1747 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1748 help 1749 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1750 the Memory Type Range Registers (MTRRs) may be used to control 1751 processor access to memory ranges. This is most useful if you have 1752 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1753 allows bus write transfers to be combined into a larger transfer 1754 before bursting over the PCI/AGP bus. This can increase performance 1755 of image write operations 2.5 times or more. Saying Y here creates a 1756 /proc/mtrr file which may be used to manipulate your processor's 1757 MTRRs. Typically the X server should use this. 1758 1759 This code has a reasonably generic interface so that similar 1760 control registers on other processors can be easily supported 1761 as well: 1762 1763 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1764 Registers (ARRs) which provide a similar functionality to MTRRs. For 1765 these, the ARRs are used to emulate the MTRRs. 1766 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1767 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1768 write-combining. All of these processors are supported by this code 1769 and it makes sense to say Y here if you have one of them. 1770 1771 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1772 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1773 can lead to all sorts of problems, so it's good to say Y here. 1774 1775 You can safely say Y even if your machine doesn't have MTRRs, you'll 1776 just add about 9 KB to your kernel. 1777 1778 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1779 1780config MTRR_SANITIZER 1781 def_bool y 1782 prompt "MTRR cleanup support" 1783 depends on MTRR 1784 help 1785 Convert MTRR layout from continuous to discrete, so X drivers can 1786 add writeback entries. 1787 1788 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1789 The largest mtrr entry size for a continuous block can be set with 1790 mtrr_chunk_size. 1791 1792 If unsure, say Y. 1793 1794config MTRR_SANITIZER_ENABLE_DEFAULT 1795 int "MTRR cleanup enable value (0-1)" 1796 range 0 1 1797 default "0" 1798 depends on MTRR_SANITIZER 1799 help 1800 Enable mtrr cleanup default value 1801 1802config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1803 int "MTRR cleanup spare reg num (0-7)" 1804 range 0 7 1805 default "1" 1806 depends on MTRR_SANITIZER 1807 help 1808 mtrr cleanup spare entries default, it can be changed via 1809 mtrr_spare_reg_nr=N on the kernel command line. 1810 1811config X86_PAT 1812 def_bool y 1813 prompt "x86 PAT support" if EXPERT 1814 depends on MTRR 1815 help 1816 Use PAT attributes to setup page level cache control. 1817 1818 PATs are the modern equivalents of MTRRs and are much more 1819 flexible than MTRRs. 1820 1821 Say N here if you see bootup problems (boot crash, boot hang, 1822 spontaneous reboots) or a non-working video driver. 1823 1824 If unsure, say Y. 1825 1826config ARCH_USES_PG_UNCACHED 1827 def_bool y 1828 depends on X86_PAT 1829 1830config X86_UMIP 1831 def_bool y 1832 prompt "User Mode Instruction Prevention" if EXPERT 1833 help 1834 User Mode Instruction Prevention (UMIP) is a security feature in 1835 some x86 processors. If enabled, a general protection fault is 1836 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1837 executed in user mode. These instructions unnecessarily expose 1838 information about the hardware state. 1839 1840 The vast majority of applications do not use these instructions. 1841 For the very few that do, software emulation is provided in 1842 specific cases in protected and virtual-8086 modes. Emulated 1843 results are dummy. 1844 1845config CC_HAS_IBT 1846 # GCC >= 9 and binutils >= 2.29 1847 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1848 # Clang/LLVM >= 14 1849 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1850 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1851 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1852 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1853 $(as-instr,endbr64) 1854 1855config X86_KERNEL_IBT 1856 prompt "Indirect Branch Tracking" 1857 def_bool y 1858 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1859 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1860 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1861 select OBJTOOL 1862 help 1863 Build the kernel with support for Indirect Branch Tracking, a 1864 hardware support course-grain forward-edge Control Flow Integrity 1865 protection. It enforces that all indirect calls must land on 1866 an ENDBR instruction, as such, the compiler will instrument the 1867 code with them to make this happen. 1868 1869 In addition to building the kernel with IBT, seal all functions that 1870 are not indirect call targets, avoiding them ever becoming one. 1871 1872 This requires LTO like objtool runs and will slow down the build. It 1873 does significantly reduce the number of ENDBR instructions in the 1874 kernel image. 1875 1876config X86_INTEL_MEMORY_PROTECTION_KEYS 1877 prompt "Memory Protection Keys" 1878 def_bool y 1879 # Note: only available in 64-bit mode 1880 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1881 select ARCH_USES_HIGH_VMA_FLAGS 1882 select ARCH_HAS_PKEYS 1883 help 1884 Memory Protection Keys provides a mechanism for enforcing 1885 page-based protections, but without requiring modification of the 1886 page tables when an application changes protection domains. 1887 1888 For details, see Documentation/core-api/protection-keys.rst 1889 1890 If unsure, say y. 1891 1892choice 1893 prompt "TSX enable mode" 1894 depends on CPU_SUP_INTEL 1895 default X86_INTEL_TSX_MODE_OFF 1896 help 1897 Intel's TSX (Transactional Synchronization Extensions) feature 1898 allows to optimize locking protocols through lock elision which 1899 can lead to a noticeable performance boost. 1900 1901 On the other hand it has been shown that TSX can be exploited 1902 to form side channel attacks (e.g. TAA) and chances are there 1903 will be more of those attacks discovered in the future. 1904 1905 Therefore TSX is not enabled by default (aka tsx=off). An admin 1906 might override this decision by tsx=on the command line parameter. 1907 Even with TSX enabled, the kernel will attempt to enable the best 1908 possible TAA mitigation setting depending on the microcode available 1909 for the particular machine. 1910 1911 This option allows to set the default tsx mode between tsx=on, =off 1912 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1913 details. 1914 1915 Say off if not sure, auto if TSX is in use but it should be used on safe 1916 platforms or on if TSX is in use and the security aspect of tsx is not 1917 relevant. 1918 1919config X86_INTEL_TSX_MODE_OFF 1920 bool "off" 1921 help 1922 TSX is disabled if possible - equals to tsx=off command line parameter. 1923 1924config X86_INTEL_TSX_MODE_ON 1925 bool "on" 1926 help 1927 TSX is always enabled on TSX capable HW - equals the tsx=on command 1928 line parameter. 1929 1930config X86_INTEL_TSX_MODE_AUTO 1931 bool "auto" 1932 help 1933 TSX is enabled on TSX capable HW that is believed to be safe against 1934 side channel attacks- equals the tsx=auto command line parameter. 1935endchoice 1936 1937config X86_SGX 1938 bool "Software Guard eXtensions (SGX)" 1939 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1940 depends on CRYPTO=y 1941 depends on CRYPTO_SHA256=y 1942 select MMU_NOTIFIER 1943 select NUMA_KEEP_MEMINFO if NUMA 1944 select XARRAY_MULTI 1945 help 1946 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1947 that can be used by applications to set aside private regions of code 1948 and data, referred to as enclaves. An enclave's private memory can 1949 only be accessed by code running within the enclave. Accesses from 1950 outside the enclave, including other enclaves, are disallowed by 1951 hardware. 1952 1953 If unsure, say N. 1954 1955config EFI 1956 bool "EFI runtime service support" 1957 depends on ACPI 1958 select UCS2_STRING 1959 select EFI_RUNTIME_WRAPPERS 1960 select ARCH_USE_MEMREMAP_PROT 1961 help 1962 This enables the kernel to use EFI runtime services that are 1963 available (such as the EFI variable services). 1964 1965 This option is only useful on systems that have EFI firmware. 1966 In addition, you should use the latest ELILO loader available 1967 at <http://elilo.sourceforge.net> in order to take advantage 1968 of EFI runtime services. However, even with this option, the 1969 resultant kernel should continue to boot on existing non-EFI 1970 platforms. 1971 1972config EFI_STUB 1973 bool "EFI stub support" 1974 depends on EFI 1975 select RELOCATABLE 1976 help 1977 This kernel feature allows a bzImage to be loaded directly 1978 by EFI firmware without the use of a bootloader. 1979 1980 See Documentation/admin-guide/efi-stub.rst for more information. 1981 1982config EFI_HANDOVER_PROTOCOL 1983 bool "EFI handover protocol (DEPRECATED)" 1984 depends on EFI_STUB 1985 default y 1986 help 1987 Select this in order to include support for the deprecated EFI 1988 handover protocol, which defines alternative entry points into the 1989 EFI stub. This is a practice that has no basis in the UEFI 1990 specification, and requires a priori knowledge on the part of the 1991 bootloader about Linux/x86 specific ways of passing the command line 1992 and initrd, and where in memory those assets may be loaded. 1993 1994 If in doubt, say Y. Even though the corresponding support is not 1995 present in upstream GRUB or other bootloaders, most distros build 1996 GRUB with numerous downstream patches applied, and may rely on the 1997 handover protocol as as result. 1998 1999config EFI_MIXED 2000 bool "EFI mixed-mode support" 2001 depends on EFI_STUB && X86_64 2002 help 2003 Enabling this feature allows a 64-bit kernel to be booted 2004 on a 32-bit firmware, provided that your CPU supports 64-bit 2005 mode. 2006 2007 Note that it is not possible to boot a mixed-mode enabled 2008 kernel via the EFI boot stub - a bootloader that supports 2009 the EFI handover protocol must be used. 2010 2011 If unsure, say N. 2012 2013config EFI_FAKE_MEMMAP 2014 bool "Enable EFI fake memory map" 2015 depends on EFI 2016 help 2017 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2018 this parameter, you can add arbitrary attribute to specific memory 2019 range by updating original (firmware provided) EFI memmap. This is 2020 useful for debugging of EFI memmap related feature, e.g., Address 2021 Range Mirroring feature. 2022 2023config EFI_MAX_FAKE_MEM 2024 int "maximum allowable number of ranges in efi_fake_mem boot option" 2025 depends on EFI_FAKE_MEMMAP 2026 range 1 128 2027 default 8 2028 help 2029 Maximum allowable number of ranges in efi_fake_mem boot option. 2030 Ranges can be set up to this value using comma-separated list. 2031 The default value is 8. 2032 2033config EFI_RUNTIME_MAP 2034 bool "Export EFI runtime maps to sysfs" if EXPERT 2035 depends on EFI 2036 default KEXEC_CORE 2037 help 2038 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2039 That memory map is required by the 2nd kernel to set up EFI virtual 2040 mappings after kexec, but can also be used for debugging purposes. 2041 2042 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2043 2044source "kernel/Kconfig.hz" 2045 2046config KEXEC 2047 bool "kexec system call" 2048 select KEXEC_CORE 2049 help 2050 kexec is a system call that implements the ability to shutdown your 2051 current kernel, and to start another kernel. It is like a reboot 2052 but it is independent of the system firmware. And like a reboot 2053 you can start any kernel with it, not just Linux. 2054 2055 The name comes from the similarity to the exec system call. 2056 2057 It is an ongoing process to be certain the hardware in a machine 2058 is properly shutdown, so do not be surprised if this code does not 2059 initially work for you. As of this writing the exact hardware 2060 interface is strongly in flux, so no good recommendation can be 2061 made. 2062 2063config KEXEC_FILE 2064 bool "kexec file based system call" 2065 select KEXEC_CORE 2066 select HAVE_IMA_KEXEC if IMA 2067 depends on X86_64 2068 depends on CRYPTO=y 2069 depends on CRYPTO_SHA256=y 2070 help 2071 This is new version of kexec system call. This system call is 2072 file based and takes file descriptors as system call argument 2073 for kernel and initramfs as opposed to list of segments as 2074 accepted by previous system call. 2075 2076config ARCH_HAS_KEXEC_PURGATORY 2077 def_bool KEXEC_FILE 2078 2079config KEXEC_SIG 2080 bool "Verify kernel signature during kexec_file_load() syscall" 2081 depends on KEXEC_FILE 2082 help 2083 2084 This option makes the kexec_file_load() syscall check for a valid 2085 signature of the kernel image. The image can still be loaded without 2086 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2087 there's a signature that we can check, then it must be valid. 2088 2089 In addition to this option, you need to enable signature 2090 verification for the corresponding kernel image type being 2091 loaded in order for this to work. 2092 2093config KEXEC_SIG_FORCE 2094 bool "Require a valid signature in kexec_file_load() syscall" 2095 depends on KEXEC_SIG 2096 help 2097 This option makes kernel signature verification mandatory for 2098 the kexec_file_load() syscall. 2099 2100config KEXEC_BZIMAGE_VERIFY_SIG 2101 bool "Enable bzImage signature verification support" 2102 depends on KEXEC_SIG 2103 depends on SIGNED_PE_FILE_VERIFICATION 2104 select SYSTEM_TRUSTED_KEYRING 2105 help 2106 Enable bzImage signature verification support. 2107 2108config CRASH_DUMP 2109 bool "kernel crash dumps" 2110 depends on X86_64 || (X86_32 && HIGHMEM) 2111 help 2112 Generate crash dump after being started by kexec. 2113 This should be normally only set in special crash dump kernels 2114 which are loaded in the main kernel with kexec-tools into 2115 a specially reserved region and then later executed after 2116 a crash by kdump/kexec. The crash dump kernel must be compiled 2117 to a memory address not used by the main kernel or BIOS using 2118 PHYSICAL_START, or it must be built as a relocatable image 2119 (CONFIG_RELOCATABLE=y). 2120 For more details see Documentation/admin-guide/kdump/kdump.rst 2121 2122config KEXEC_JUMP 2123 bool "kexec jump" 2124 depends on KEXEC && HIBERNATION 2125 help 2126 Jump between original kernel and kexeced kernel and invoke 2127 code in physical address mode via KEXEC 2128 2129config PHYSICAL_START 2130 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2131 default "0x1000000" 2132 help 2133 This gives the physical address where the kernel is loaded. 2134 2135 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2136 bzImage will decompress itself to above physical address and 2137 run from there. Otherwise, bzImage will run from the address where 2138 it has been loaded by the boot loader and will ignore above physical 2139 address. 2140 2141 In normal kdump cases one does not have to set/change this option 2142 as now bzImage can be compiled as a completely relocatable image 2143 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2144 address. This option is mainly useful for the folks who don't want 2145 to use a bzImage for capturing the crash dump and want to use a 2146 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2147 to be specifically compiled to run from a specific memory area 2148 (normally a reserved region) and this option comes handy. 2149 2150 So if you are using bzImage for capturing the crash dump, 2151 leave the value here unchanged to 0x1000000 and set 2152 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2153 for capturing the crash dump change this value to start of 2154 the reserved region. In other words, it can be set based on 2155 the "X" value as specified in the "crashkernel=YM@XM" 2156 command line boot parameter passed to the panic-ed 2157 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2158 for more details about crash dumps. 2159 2160 Usage of bzImage for capturing the crash dump is recommended as 2161 one does not have to build two kernels. Same kernel can be used 2162 as production kernel and capture kernel. Above option should have 2163 gone away after relocatable bzImage support is introduced. But it 2164 is present because there are users out there who continue to use 2165 vmlinux for dump capture. This option should go away down the 2166 line. 2167 2168 Don't change this unless you know what you are doing. 2169 2170config RELOCATABLE 2171 bool "Build a relocatable kernel" 2172 default y 2173 help 2174 This builds a kernel image that retains relocation information 2175 so it can be loaded someplace besides the default 1MB. 2176 The relocations tend to make the kernel binary about 10% larger, 2177 but are discarded at runtime. 2178 2179 One use is for the kexec on panic case where the recovery kernel 2180 must live at a different physical address than the primary 2181 kernel. 2182 2183 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2184 it has been loaded at and the compile time physical address 2185 (CONFIG_PHYSICAL_START) is used as the minimum location. 2186 2187config RANDOMIZE_BASE 2188 bool "Randomize the address of the kernel image (KASLR)" 2189 depends on RELOCATABLE 2190 default y 2191 help 2192 In support of Kernel Address Space Layout Randomization (KASLR), 2193 this randomizes the physical address at which the kernel image 2194 is decompressed and the virtual address where the kernel 2195 image is mapped, as a security feature that deters exploit 2196 attempts relying on knowledge of the location of kernel 2197 code internals. 2198 2199 On 64-bit, the kernel physical and virtual addresses are 2200 randomized separately. The physical address will be anywhere 2201 between 16MB and the top of physical memory (up to 64TB). The 2202 virtual address will be randomized from 16MB up to 1GB (9 bits 2203 of entropy). Note that this also reduces the memory space 2204 available to kernel modules from 1.5GB to 1GB. 2205 2206 On 32-bit, the kernel physical and virtual addresses are 2207 randomized together. They will be randomized from 16MB up to 2208 512MB (8 bits of entropy). 2209 2210 Entropy is generated using the RDRAND instruction if it is 2211 supported. If RDTSC is supported, its value is mixed into 2212 the entropy pool as well. If neither RDRAND nor RDTSC are 2213 supported, then entropy is read from the i8254 timer. The 2214 usable entropy is limited by the kernel being built using 2215 2GB addressing, and that PHYSICAL_ALIGN must be at a 2216 minimum of 2MB. As a result, only 10 bits of entropy are 2217 theoretically possible, but the implementations are further 2218 limited due to memory layouts. 2219 2220 If unsure, say Y. 2221 2222# Relocation on x86 needs some additional build support 2223config X86_NEED_RELOCS 2224 def_bool y 2225 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2226 2227config PHYSICAL_ALIGN 2228 hex "Alignment value to which kernel should be aligned" 2229 default "0x200000" 2230 range 0x2000 0x1000000 if X86_32 2231 range 0x200000 0x1000000 if X86_64 2232 help 2233 This value puts the alignment restrictions on physical address 2234 where kernel is loaded and run from. Kernel is compiled for an 2235 address which meets above alignment restriction. 2236 2237 If bootloader loads the kernel at a non-aligned address and 2238 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2239 address aligned to above value and run from there. 2240 2241 If bootloader loads the kernel at a non-aligned address and 2242 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2243 load address and decompress itself to the address it has been 2244 compiled for and run from there. The address for which kernel is 2245 compiled already meets above alignment restrictions. Hence the 2246 end result is that kernel runs from a physical address meeting 2247 above alignment restrictions. 2248 2249 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2250 this value must be a multiple of 0x200000. 2251 2252 Don't change this unless you know what you are doing. 2253 2254config DYNAMIC_MEMORY_LAYOUT 2255 bool 2256 help 2257 This option makes base addresses of vmalloc and vmemmap as well as 2258 __PAGE_OFFSET movable during boot. 2259 2260config RANDOMIZE_MEMORY 2261 bool "Randomize the kernel memory sections" 2262 depends on X86_64 2263 depends on RANDOMIZE_BASE 2264 select DYNAMIC_MEMORY_LAYOUT 2265 default RANDOMIZE_BASE 2266 help 2267 Randomizes the base virtual address of kernel memory sections 2268 (physical memory mapping, vmalloc & vmemmap). This security feature 2269 makes exploits relying on predictable memory locations less reliable. 2270 2271 The order of allocations remains unchanged. Entropy is generated in 2272 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2273 configuration have in average 30,000 different possible virtual 2274 addresses for each memory section. 2275 2276 If unsure, say Y. 2277 2278config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2279 hex "Physical memory mapping padding" if EXPERT 2280 depends on RANDOMIZE_MEMORY 2281 default "0xa" if MEMORY_HOTPLUG 2282 default "0x0" 2283 range 0x1 0x40 if MEMORY_HOTPLUG 2284 range 0x0 0x40 2285 help 2286 Define the padding in terabytes added to the existing physical 2287 memory size during kernel memory randomization. It is useful 2288 for memory hotplug support but reduces the entropy available for 2289 address randomization. 2290 2291 If unsure, leave at the default value. 2292 2293config ADDRESS_MASKING 2294 bool "Linear Address Masking support" 2295 depends on X86_64 2296 help 2297 Linear Address Masking (LAM) modifies the checking that is applied 2298 to 64-bit linear addresses, allowing software to use of the 2299 untranslated address bits for metadata. 2300 2301 The capability can be used for efficient address sanitizers (ASAN) 2302 implementation and for optimizations in JITs. 2303 2304config HOTPLUG_CPU 2305 def_bool y 2306 depends on SMP 2307 2308config BOOTPARAM_HOTPLUG_CPU0 2309 bool "Set default setting of cpu0_hotpluggable" 2310 depends on HOTPLUG_CPU 2311 help 2312 Set whether default state of cpu0_hotpluggable is on or off. 2313 2314 Say Y here to enable CPU0 hotplug by default. If this switch 2315 is turned on, there is no need to give cpu0_hotplug kernel 2316 parameter and the CPU0 hotplug feature is enabled by default. 2317 2318 Please note: there are two known CPU0 dependencies if you want 2319 to enable the CPU0 hotplug feature either by this switch or by 2320 cpu0_hotplug kernel parameter. 2321 2322 First, resume from hibernate or suspend always starts from CPU0. 2323 So hibernate and suspend are prevented if CPU0 is offline. 2324 2325 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2326 offline if any interrupt can not migrate out of CPU0. There may 2327 be other CPU0 dependencies. 2328 2329 Please make sure the dependencies are under your control before 2330 you enable this feature. 2331 2332 Say N if you don't want to enable CPU0 hotplug feature by default. 2333 You still can enable the CPU0 hotplug feature at boot by kernel 2334 parameter cpu0_hotplug. 2335 2336config DEBUG_HOTPLUG_CPU0 2337 def_bool n 2338 prompt "Debug CPU0 hotplug" 2339 depends on HOTPLUG_CPU 2340 help 2341 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2342 soon as possible and boots up userspace with CPU0 offlined. User 2343 can online CPU0 back after boot time. 2344 2345 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2346 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2347 compilation or giving cpu0_hotplug kernel parameter at boot. 2348 2349 If unsure, say N. 2350 2351config COMPAT_VDSO 2352 def_bool n 2353 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2354 depends on COMPAT_32 2355 help 2356 Certain buggy versions of glibc will crash if they are 2357 presented with a 32-bit vDSO that is not mapped at the address 2358 indicated in its segment table. 2359 2360 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2361 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2362 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2363 the only released version with the bug, but OpenSUSE 9 2364 contains a buggy "glibc 2.3.2". 2365 2366 The symptom of the bug is that everything crashes on startup, saying: 2367 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2368 2369 Saying Y here changes the default value of the vdso32 boot 2370 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2371 This works around the glibc bug but hurts performance. 2372 2373 If unsure, say N: if you are compiling your own kernel, you 2374 are unlikely to be using a buggy version of glibc. 2375 2376choice 2377 prompt "vsyscall table for legacy applications" 2378 depends on X86_64 2379 default LEGACY_VSYSCALL_XONLY 2380 help 2381 Legacy user code that does not know how to find the vDSO expects 2382 to be able to issue three syscalls by calling fixed addresses in 2383 kernel space. Since this location is not randomized with ASLR, 2384 it can be used to assist security vulnerability exploitation. 2385 2386 This setting can be changed at boot time via the kernel command 2387 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2388 is deprecated and can only be enabled using the kernel command 2389 line. 2390 2391 On a system with recent enough glibc (2.14 or newer) and no 2392 static binaries, you can say None without a performance penalty 2393 to improve security. 2394 2395 If unsure, select "Emulate execution only". 2396 2397 config LEGACY_VSYSCALL_XONLY 2398 bool "Emulate execution only" 2399 help 2400 The kernel traps and emulates calls into the fixed vsyscall 2401 address mapping and does not allow reads. This 2402 configuration is recommended when userspace might use the 2403 legacy vsyscall area but support for legacy binary 2404 instrumentation of legacy code is not needed. It mitigates 2405 certain uses of the vsyscall area as an ASLR-bypassing 2406 buffer. 2407 2408 config LEGACY_VSYSCALL_NONE 2409 bool "None" 2410 help 2411 There will be no vsyscall mapping at all. This will 2412 eliminate any risk of ASLR bypass due to the vsyscall 2413 fixed address mapping. Attempts to use the vsyscalls 2414 will be reported to dmesg, so that either old or 2415 malicious userspace programs can be identified. 2416 2417endchoice 2418 2419config CMDLINE_BOOL 2420 bool "Built-in kernel command line" 2421 help 2422 Allow for specifying boot arguments to the kernel at 2423 build time. On some systems (e.g. embedded ones), it is 2424 necessary or convenient to provide some or all of the 2425 kernel boot arguments with the kernel itself (that is, 2426 to not rely on the boot loader to provide them.) 2427 2428 To compile command line arguments into the kernel, 2429 set this option to 'Y', then fill in the 2430 boot arguments in CONFIG_CMDLINE. 2431 2432 Systems with fully functional boot loaders (i.e. non-embedded) 2433 should leave this option set to 'N'. 2434 2435config CMDLINE 2436 string "Built-in kernel command string" 2437 depends on CMDLINE_BOOL 2438 default "" 2439 help 2440 Enter arguments here that should be compiled into the kernel 2441 image and used at boot time. If the boot loader provides a 2442 command line at boot time, it is appended to this string to 2443 form the full kernel command line, when the system boots. 2444 2445 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2446 change this behavior. 2447 2448 In most cases, the command line (whether built-in or provided 2449 by the boot loader) should specify the device for the root 2450 file system. 2451 2452config CMDLINE_OVERRIDE 2453 bool "Built-in command line overrides boot loader arguments" 2454 depends on CMDLINE_BOOL && CMDLINE != "" 2455 help 2456 Set this option to 'Y' to have the kernel ignore the boot loader 2457 command line, and use ONLY the built-in command line. 2458 2459 This is used to work around broken boot loaders. This should 2460 be set to 'N' under normal conditions. 2461 2462config MODIFY_LDT_SYSCALL 2463 bool "Enable the LDT (local descriptor table)" if EXPERT 2464 default y 2465 help 2466 Linux can allow user programs to install a per-process x86 2467 Local Descriptor Table (LDT) using the modify_ldt(2) system 2468 call. This is required to run 16-bit or segmented code such as 2469 DOSEMU or some Wine programs. It is also used by some very old 2470 threading libraries. 2471 2472 Enabling this feature adds a small amount of overhead to 2473 context switches and increases the low-level kernel attack 2474 surface. Disabling it removes the modify_ldt(2) system call. 2475 2476 Saying 'N' here may make sense for embedded or server kernels. 2477 2478config STRICT_SIGALTSTACK_SIZE 2479 bool "Enforce strict size checking for sigaltstack" 2480 depends on DYNAMIC_SIGFRAME 2481 help 2482 For historical reasons MINSIGSTKSZ is a constant which became 2483 already too small with AVX512 support. Add a mechanism to 2484 enforce strict checking of the sigaltstack size against the 2485 real size of the FPU frame. This option enables the check 2486 by default. It can also be controlled via the kernel command 2487 line option 'strict_sas_size' independent of this config 2488 switch. Enabling it might break existing applications which 2489 allocate a too small sigaltstack but 'work' because they 2490 never get a signal delivered. 2491 2492 Say 'N' unless you want to really enforce this check. 2493 2494source "kernel/livepatch/Kconfig" 2495 2496endmenu 2497 2498config CC_HAS_SLS 2499 def_bool $(cc-option,-mharden-sls=all) 2500 2501config CC_HAS_RETURN_THUNK 2502 def_bool $(cc-option,-mfunction-return=thunk-extern) 2503 2504config CC_HAS_ENTRY_PADDING 2505 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2506 2507config FUNCTION_PADDING_CFI 2508 int 2509 default 59 if FUNCTION_ALIGNMENT_64B 2510 default 27 if FUNCTION_ALIGNMENT_32B 2511 default 11 if FUNCTION_ALIGNMENT_16B 2512 default 3 if FUNCTION_ALIGNMENT_8B 2513 default 0 2514 2515# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2516# except Kconfig can't do arithmetic :/ 2517config FUNCTION_PADDING_BYTES 2518 int 2519 default FUNCTION_PADDING_CFI if CFI_CLANG 2520 default FUNCTION_ALIGNMENT 2521 2522config CALL_PADDING 2523 def_bool n 2524 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2525 select FUNCTION_ALIGNMENT_16B 2526 2527config FINEIBT 2528 def_bool y 2529 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE 2530 select CALL_PADDING 2531 2532config HAVE_CALL_THUNKS 2533 def_bool y 2534 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL 2535 2536config CALL_THUNKS 2537 def_bool n 2538 select CALL_PADDING 2539 2540config PREFIX_SYMBOLS 2541 def_bool y 2542 depends on CALL_PADDING && !CFI_CLANG 2543 2544menuconfig SPECULATION_MITIGATIONS 2545 bool "Mitigations for speculative execution vulnerabilities" 2546 default y 2547 help 2548 Say Y here to enable options which enable mitigations for 2549 speculative execution hardware vulnerabilities. 2550 2551 If you say N, all mitigations will be disabled. You really 2552 should know what you are doing to say so. 2553 2554if SPECULATION_MITIGATIONS 2555 2556config PAGE_TABLE_ISOLATION 2557 bool "Remove the kernel mapping in user mode" 2558 default y 2559 depends on (X86_64 || X86_PAE) 2560 help 2561 This feature reduces the number of hardware side channels by 2562 ensuring that the majority of kernel addresses are not mapped 2563 into userspace. 2564 2565 See Documentation/arch/x86/pti.rst for more details. 2566 2567config RETPOLINE 2568 bool "Avoid speculative indirect branches in kernel" 2569 select OBJTOOL if HAVE_OBJTOOL 2570 default y 2571 help 2572 Compile kernel with the retpoline compiler options to guard against 2573 kernel-to-user data leaks by avoiding speculative indirect 2574 branches. Requires a compiler with -mindirect-branch=thunk-extern 2575 support for full protection. The kernel may run slower. 2576 2577config RETHUNK 2578 bool "Enable return-thunks" 2579 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2580 select OBJTOOL if HAVE_OBJTOOL 2581 default y if X86_64 2582 help 2583 Compile the kernel with the return-thunks compiler option to guard 2584 against kernel-to-user data leaks by avoiding return speculation. 2585 Requires a compiler with -mfunction-return=thunk-extern 2586 support for full protection. The kernel may run slower. 2587 2588config CPU_UNRET_ENTRY 2589 bool "Enable UNRET on kernel entry" 2590 depends on CPU_SUP_AMD && RETHUNK && X86_64 2591 default y 2592 help 2593 Compile the kernel with support for the retbleed=unret mitigation. 2594 2595config CALL_DEPTH_TRACKING 2596 bool "Mitigate RSB underflow with call depth tracking" 2597 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2598 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2599 select CALL_THUNKS 2600 default y 2601 help 2602 Compile the kernel with call depth tracking to mitigate the Intel 2603 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2604 mitigation is off by default and needs to be enabled on the 2605 kernel command line via the retbleed=stuff option. For 2606 non-affected systems the overhead of this option is marginal as 2607 the call depth tracking is using run-time generated call thunks 2608 in a compiler generated padding area and call patching. This 2609 increases text size by ~5%. For non affected systems this space 2610 is unused. On affected SKL systems this results in a significant 2611 performance gain over the IBRS mitigation. 2612 2613config CALL_THUNKS_DEBUG 2614 bool "Enable call thunks and call depth tracking debugging" 2615 depends on CALL_DEPTH_TRACKING 2616 select FUNCTION_ALIGNMENT_32B 2617 default n 2618 help 2619 Enable call/ret counters for imbalance detection and build in 2620 a noisy dmesg about callthunks generation and call patching for 2621 trouble shooting. The debug prints need to be enabled on the 2622 kernel command line with 'debug-callthunks'. 2623 Only enable this when you are debugging call thunks as this 2624 creates a noticeable runtime overhead. If unsure say N. 2625 2626config CPU_IBPB_ENTRY 2627 bool "Enable IBPB on kernel entry" 2628 depends on CPU_SUP_AMD && X86_64 2629 default y 2630 help 2631 Compile the kernel with support for the retbleed=ibpb mitigation. 2632 2633config CPU_IBRS_ENTRY 2634 bool "Enable IBRS on kernel entry" 2635 depends on CPU_SUP_INTEL && X86_64 2636 default y 2637 help 2638 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2639 This mitigates both spectre_v2 and retbleed at great cost to 2640 performance. 2641 2642config SLS 2643 bool "Mitigate Straight-Line-Speculation" 2644 depends on CC_HAS_SLS && X86_64 2645 select OBJTOOL if HAVE_OBJTOOL 2646 default n 2647 help 2648 Compile the kernel with straight-line-speculation options to guard 2649 against straight line speculation. The kernel image might be slightly 2650 larger. 2651 2652endif 2653 2654config ARCH_HAS_ADD_PAGES 2655 def_bool y 2656 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2657 2658config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2659 def_bool y 2660 2661menu "Power management and ACPI options" 2662 2663config ARCH_HIBERNATION_HEADER 2664 def_bool y 2665 depends on HIBERNATION 2666 2667source "kernel/power/Kconfig" 2668 2669source "drivers/acpi/Kconfig" 2670 2671config X86_APM_BOOT 2672 def_bool y 2673 depends on APM 2674 2675menuconfig APM 2676 tristate "APM (Advanced Power Management) BIOS support" 2677 depends on X86_32 && PM_SLEEP 2678 help 2679 APM is a BIOS specification for saving power using several different 2680 techniques. This is mostly useful for battery powered laptops with 2681 APM compliant BIOSes. If you say Y here, the system time will be 2682 reset after a RESUME operation, the /proc/apm device will provide 2683 battery status information, and user-space programs will receive 2684 notification of APM "events" (e.g. battery status change). 2685 2686 If you select "Y" here, you can disable actual use of the APM 2687 BIOS by passing the "apm=off" option to the kernel at boot time. 2688 2689 Note that the APM support is almost completely disabled for 2690 machines with more than one CPU. 2691 2692 In order to use APM, you will need supporting software. For location 2693 and more information, read <file:Documentation/power/apm-acpi.rst> 2694 and the Battery Powered Linux mini-HOWTO, available from 2695 <http://www.tldp.org/docs.html#howto>. 2696 2697 This driver does not spin down disk drives (see the hdparm(8) 2698 manpage ("man 8 hdparm") for that), and it doesn't turn off 2699 VESA-compliant "green" monitors. 2700 2701 This driver does not support the TI 4000M TravelMate and the ACER 2702 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2703 desktop machines also don't have compliant BIOSes, and this driver 2704 may cause those machines to panic during the boot phase. 2705 2706 Generally, if you don't have a battery in your machine, there isn't 2707 much point in using this driver and you should say N. If you get 2708 random kernel OOPSes or reboots that don't seem to be related to 2709 anything, try disabling/enabling this option (or disabling/enabling 2710 APM in your BIOS). 2711 2712 Some other things you should try when experiencing seemingly random, 2713 "weird" problems: 2714 2715 1) make sure that you have enough swap space and that it is 2716 enabled. 2717 2) pass the "idle=poll" option to the kernel 2718 3) switch on floating point emulation in the kernel and pass 2719 the "no387" option to the kernel 2720 4) pass the "floppy=nodma" option to the kernel 2721 5) pass the "mem=4M" option to the kernel (thereby disabling 2722 all but the first 4 MB of RAM) 2723 6) make sure that the CPU is not over clocked. 2724 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2725 8) disable the cache from your BIOS settings 2726 9) install a fan for the video card or exchange video RAM 2727 10) install a better fan for the CPU 2728 11) exchange RAM chips 2729 12) exchange the motherboard. 2730 2731 To compile this driver as a module, choose M here: the 2732 module will be called apm. 2733 2734if APM 2735 2736config APM_IGNORE_USER_SUSPEND 2737 bool "Ignore USER SUSPEND" 2738 help 2739 This option will ignore USER SUSPEND requests. On machines with a 2740 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2741 series notebooks, it is necessary to say Y because of a BIOS bug. 2742 2743config APM_DO_ENABLE 2744 bool "Enable PM at boot time" 2745 help 2746 Enable APM features at boot time. From page 36 of the APM BIOS 2747 specification: "When disabled, the APM BIOS does not automatically 2748 power manage devices, enter the Standby State, enter the Suspend 2749 State, or take power saving steps in response to CPU Idle calls." 2750 This driver will make CPU Idle calls when Linux is idle (unless this 2751 feature is turned off -- see "Do CPU IDLE calls", below). This 2752 should always save battery power, but more complicated APM features 2753 will be dependent on your BIOS implementation. You may need to turn 2754 this option off if your computer hangs at boot time when using APM 2755 support, or if it beeps continuously instead of suspending. Turn 2756 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2757 T400CDT. This is off by default since most machines do fine without 2758 this feature. 2759 2760config APM_CPU_IDLE 2761 depends on CPU_IDLE 2762 bool "Make CPU Idle calls when idle" 2763 help 2764 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2765 On some machines, this can activate improved power savings, such as 2766 a slowed CPU clock rate, when the machine is idle. These idle calls 2767 are made after the idle loop has run for some length of time (e.g., 2768 333 mS). On some machines, this will cause a hang at boot time or 2769 whenever the CPU becomes idle. (On machines with more than one CPU, 2770 this option does nothing.) 2771 2772config APM_DISPLAY_BLANK 2773 bool "Enable console blanking using APM" 2774 help 2775 Enable console blanking using the APM. Some laptops can use this to 2776 turn off the LCD backlight when the screen blanker of the Linux 2777 virtual console blanks the screen. Note that this is only used by 2778 the virtual console screen blanker, and won't turn off the backlight 2779 when using the X Window system. This also doesn't have anything to 2780 do with your VESA-compliant power-saving monitor. Further, this 2781 option doesn't work for all laptops -- it might not turn off your 2782 backlight at all, or it might print a lot of errors to the console, 2783 especially if you are using gpm. 2784 2785config APM_ALLOW_INTS 2786 bool "Allow interrupts during APM BIOS calls" 2787 help 2788 Normally we disable external interrupts while we are making calls to 2789 the APM BIOS as a measure to lessen the effects of a badly behaving 2790 BIOS implementation. The BIOS should reenable interrupts if it 2791 needs to. Unfortunately, some BIOSes do not -- especially those in 2792 many of the newer IBM Thinkpads. If you experience hangs when you 2793 suspend, try setting this to Y. Otherwise, say N. 2794 2795endif # APM 2796 2797source "drivers/cpufreq/Kconfig" 2798 2799source "drivers/cpuidle/Kconfig" 2800 2801source "drivers/idle/Kconfig" 2802 2803endmenu 2804 2805menu "Bus options (PCI etc.)" 2806 2807choice 2808 prompt "PCI access mode" 2809 depends on X86_32 && PCI 2810 default PCI_GOANY 2811 help 2812 On PCI systems, the BIOS can be used to detect the PCI devices and 2813 determine their configuration. However, some old PCI motherboards 2814 have BIOS bugs and may crash if this is done. Also, some embedded 2815 PCI-based systems don't have any BIOS at all. Linux can also try to 2816 detect the PCI hardware directly without using the BIOS. 2817 2818 With this option, you can specify how Linux should detect the 2819 PCI devices. If you choose "BIOS", the BIOS will be used, 2820 if you choose "Direct", the BIOS won't be used, and if you 2821 choose "MMConfig", then PCI Express MMCONFIG will be used. 2822 If you choose "Any", the kernel will try MMCONFIG, then the 2823 direct access method and falls back to the BIOS if that doesn't 2824 work. If unsure, go with the default, which is "Any". 2825 2826config PCI_GOBIOS 2827 bool "BIOS" 2828 2829config PCI_GOMMCONFIG 2830 bool "MMConfig" 2831 2832config PCI_GODIRECT 2833 bool "Direct" 2834 2835config PCI_GOOLPC 2836 bool "OLPC XO-1" 2837 depends on OLPC 2838 2839config PCI_GOANY 2840 bool "Any" 2841 2842endchoice 2843 2844config PCI_BIOS 2845 def_bool y 2846 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2847 2848# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2849config PCI_DIRECT 2850 def_bool y 2851 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2852 2853config PCI_MMCONFIG 2854 bool "Support mmconfig PCI config space access" if X86_64 2855 default y 2856 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2857 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2858 2859config PCI_OLPC 2860 def_bool y 2861 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2862 2863config PCI_XEN 2864 def_bool y 2865 depends on PCI && XEN 2866 2867config MMCONF_FAM10H 2868 def_bool y 2869 depends on X86_64 && PCI_MMCONFIG && ACPI 2870 2871config PCI_CNB20LE_QUIRK 2872 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2873 depends on PCI 2874 help 2875 Read the PCI windows out of the CNB20LE host bridge. This allows 2876 PCI hotplug to work on systems with the CNB20LE chipset which do 2877 not have ACPI. 2878 2879 There's no public spec for this chipset, and this functionality 2880 is known to be incomplete. 2881 2882 You should say N unless you know you need this. 2883 2884config ISA_BUS 2885 bool "ISA bus support on modern systems" if EXPERT 2886 help 2887 Expose ISA bus device drivers and options available for selection and 2888 configuration. Enable this option if your target machine has an ISA 2889 bus. ISA is an older system, displaced by PCI and newer bus 2890 architectures -- if your target machine is modern, it probably does 2891 not have an ISA bus. 2892 2893 If unsure, say N. 2894 2895# x86_64 have no ISA slots, but can have ISA-style DMA. 2896config ISA_DMA_API 2897 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2898 default y 2899 help 2900 Enables ISA-style DMA support for devices requiring such controllers. 2901 If unsure, say Y. 2902 2903if X86_32 2904 2905config ISA 2906 bool "ISA support" 2907 help 2908 Find out whether you have ISA slots on your motherboard. ISA is the 2909 name of a bus system, i.e. the way the CPU talks to the other stuff 2910 inside your box. Other bus systems are PCI, EISA, MicroChannel 2911 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2912 newer boards don't support it. If you have ISA, say Y, otherwise N. 2913 2914config SCx200 2915 tristate "NatSemi SCx200 support" 2916 help 2917 This provides basic support for National Semiconductor's 2918 (now AMD's) Geode processors. The driver probes for the 2919 PCI-IDs of several on-chip devices, so its a good dependency 2920 for other scx200_* drivers. 2921 2922 If compiled as a module, the driver is named scx200. 2923 2924config SCx200HR_TIMER 2925 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2926 depends on SCx200 2927 default y 2928 help 2929 This driver provides a clocksource built upon the on-chip 2930 27MHz high-resolution timer. Its also a workaround for 2931 NSC Geode SC-1100's buggy TSC, which loses time when the 2932 processor goes idle (as is done by the scheduler). The 2933 other workaround is idle=poll boot option. 2934 2935config OLPC 2936 bool "One Laptop Per Child support" 2937 depends on !X86_PAE 2938 select GPIOLIB 2939 select OF 2940 select OF_PROMTREE 2941 select IRQ_DOMAIN 2942 select OLPC_EC 2943 help 2944 Add support for detecting the unique features of the OLPC 2945 XO hardware. 2946 2947config OLPC_XO1_PM 2948 bool "OLPC XO-1 Power Management" 2949 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2950 help 2951 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2952 2953config OLPC_XO1_RTC 2954 bool "OLPC XO-1 Real Time Clock" 2955 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2956 help 2957 Add support for the XO-1 real time clock, which can be used as a 2958 programmable wakeup source. 2959 2960config OLPC_XO1_SCI 2961 bool "OLPC XO-1 SCI extras" 2962 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2963 depends on INPUT=y 2964 select POWER_SUPPLY 2965 help 2966 Add support for SCI-based features of the OLPC XO-1 laptop: 2967 - EC-driven system wakeups 2968 - Power button 2969 - Ebook switch 2970 - Lid switch 2971 - AC adapter status updates 2972 - Battery status updates 2973 2974config OLPC_XO15_SCI 2975 bool "OLPC XO-1.5 SCI extras" 2976 depends on OLPC && ACPI 2977 select POWER_SUPPLY 2978 help 2979 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2980 - EC-driven system wakeups 2981 - AC adapter status updates 2982 - Battery status updates 2983 2984config ALIX 2985 bool "PCEngines ALIX System Support (LED setup)" 2986 select GPIOLIB 2987 help 2988 This option enables system support for the PCEngines ALIX. 2989 At present this just sets up LEDs for GPIO control on 2990 ALIX2/3/6 boards. However, other system specific setup should 2991 get added here. 2992 2993 Note: You must still enable the drivers for GPIO and LED support 2994 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2995 2996 Note: You have to set alix.force=1 for boards with Award BIOS. 2997 2998config NET5501 2999 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 3000 select GPIOLIB 3001 help 3002 This option enables system support for the Soekris Engineering net5501. 3003 3004config GEOS 3005 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3006 select GPIOLIB 3007 depends on DMI 3008 help 3009 This option enables system support for the Traverse Technologies GEOS. 3010 3011config TS5500 3012 bool "Technologic Systems TS-5500 platform support" 3013 depends on MELAN 3014 select CHECK_SIGNATURE 3015 select NEW_LEDS 3016 select LEDS_CLASS 3017 help 3018 This option enables system support for the Technologic Systems TS-5500. 3019 3020endif # X86_32 3021 3022config AMD_NB 3023 def_bool y 3024 depends on CPU_SUP_AMD && PCI 3025 3026endmenu 3027 3028menu "Binary Emulations" 3029 3030config IA32_EMULATION 3031 bool "IA32 Emulation" 3032 depends on X86_64 3033 select ARCH_WANT_OLD_COMPAT_IPC 3034 select BINFMT_ELF 3035 select COMPAT_OLD_SIGACTION 3036 help 3037 Include code to run legacy 32-bit programs under a 3038 64-bit kernel. You should likely turn this on, unless you're 3039 100% sure that you don't have any 32-bit programs left. 3040 3041config X86_X32_ABI 3042 bool "x32 ABI for 64-bit mode" 3043 depends on X86_64 3044 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3045 # compressed debug sections to x86_x32 properly: 3046 # https://github.com/ClangBuiltLinux/linux/issues/514 3047 # https://github.com/ClangBuiltLinux/linux/issues/1141 3048 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3049 help 3050 Include code to run binaries for the x32 native 32-bit ABI 3051 for 64-bit processors. An x32 process gets access to the 3052 full 64-bit register file and wide data path while leaving 3053 pointers at 32 bits for smaller memory footprint. 3054 3055config COMPAT_32 3056 def_bool y 3057 depends on IA32_EMULATION || X86_32 3058 select HAVE_UID16 3059 select OLD_SIGSUSPEND3 3060 3061config COMPAT 3062 def_bool y 3063 depends on IA32_EMULATION || X86_X32_ABI 3064 3065config COMPAT_FOR_U64_ALIGNMENT 3066 def_bool y 3067 depends on COMPAT 3068 3069endmenu 3070 3071config HAVE_ATOMIC_IOMAP 3072 def_bool y 3073 depends on X86_32 3074 3075source "arch/x86/kvm/Kconfig" 3076 3077source "arch/x86/Kconfig.assembler" 3078