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 HAVE_ARCH_SOFT_DIRTY 32 select MODULES_USE_ELF_RELA 33 select NEED_DMA_MAP_STATE 34 select SWIOTLB 35 select ARCH_HAS_ELFCORE_COMPAT 36 select ZONE_DMA32 37 select EXECMEM if DYNAMIC_FTRACE 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 ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 64 select ARCH_32BIT_OFF_T if X86_32 65 select ARCH_CLOCKSOURCE_INIT 66 select ARCH_CONFIGURES_CPU_MITIGATIONS 67 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 68 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 69 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 70 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 71 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 72 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 73 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 74 select ARCH_HAS_CACHE_LINE_SIZE 75 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 76 select ARCH_HAS_CPU_FINALIZE_INIT 77 select ARCH_HAS_CPU_PASID if IOMMU_SVA 78 select ARCH_HAS_CURRENT_STACK_POINTER 79 select ARCH_HAS_DEBUG_VIRTUAL 80 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 81 select ARCH_HAS_DEVMEM_IS_ALLOWED 82 select ARCH_HAS_EARLY_DEBUG if KGDB 83 select ARCH_HAS_ELF_RANDOMIZE 84 select ARCH_HAS_FAST_MULTIPLIER 85 select ARCH_HAS_FORTIFY_SOURCE 86 select ARCH_HAS_GCOV_PROFILE_ALL 87 select ARCH_HAS_KCOV if X86_64 88 select ARCH_HAS_MEM_ENCRYPT 89 select ARCH_HAS_MEMBARRIER_SYNC_CORE 90 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 91 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 92 select ARCH_HAS_PMEM_API if X86_64 93 select ARCH_HAS_PTE_DEVMAP if X86_64 94 select ARCH_HAS_PTE_SPECIAL 95 select ARCH_HAS_HW_PTE_YOUNG 96 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 97 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 98 select ARCH_HAS_COPY_MC if X86_64 99 select ARCH_HAS_SET_MEMORY 100 select ARCH_HAS_SET_DIRECT_MAP 101 select ARCH_HAS_STRICT_KERNEL_RWX 102 select ARCH_HAS_STRICT_MODULE_RWX 103 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 104 select ARCH_HAS_SYSCALL_WRAPPER 105 select ARCH_HAS_UBSAN 106 select ARCH_HAS_DEBUG_WX 107 select ARCH_HAS_ZONE_DMA_SET if EXPERT 108 select ARCH_HAVE_NMI_SAFE_CMPXCHG 109 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 110 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 111 select ARCH_MIGHT_HAVE_PC_PARPORT 112 select ARCH_MIGHT_HAVE_PC_SERIO 113 select ARCH_STACKWALK 114 select ARCH_SUPPORTS_ACPI 115 select ARCH_SUPPORTS_ATOMIC_RMW 116 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 117 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 118 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 119 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 120 select ARCH_SUPPORTS_CFI_CLANG if X86_64 121 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 122 select ARCH_SUPPORTS_LTO_CLANG 123 select ARCH_SUPPORTS_LTO_CLANG_THIN 124 select ARCH_USE_BUILTIN_BSWAP 125 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64 126 select ARCH_USE_MEMTEST 127 select ARCH_USE_QUEUED_RWLOCKS 128 select ARCH_USE_QUEUED_SPINLOCKS 129 select ARCH_USE_SYM_ANNOTATIONS 130 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 131 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 132 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 133 select ARCH_WANTS_NO_INSTR 134 select ARCH_WANT_GENERAL_HUGETLB 135 select ARCH_WANT_HUGE_PMD_SHARE 136 select ARCH_WANT_LD_ORPHAN_WARN 137 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 138 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 139 select ARCH_WANTS_THP_SWAP if X86_64 140 select ARCH_HAS_PARANOID_L1D_FLUSH 141 select BUILDTIME_TABLE_SORT 142 select CLKEVT_I8253 143 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 144 select CLOCKSOURCE_WATCHDOG 145 # Word-size accesses may read uninitialized data past the trailing \0 146 # in strings and cause false KMSAN reports. 147 select DCACHE_WORD_ACCESS if !KMSAN 148 select DYNAMIC_SIGFRAME 149 select EDAC_ATOMIC_SCRUB 150 select EDAC_SUPPORT 151 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 152 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST 153 select GENERIC_CLOCKEVENTS_MIN_ADJUST 154 select GENERIC_CMOS_UPDATE 155 select GENERIC_CPU_AUTOPROBE 156 select GENERIC_CPU_DEVICES 157 select GENERIC_CPU_VULNERABILITIES 158 select GENERIC_EARLY_IOREMAP 159 select GENERIC_ENTRY 160 select GENERIC_IOMAP 161 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 162 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 163 select GENERIC_IRQ_MIGRATION if SMP 164 select GENERIC_IRQ_PROBE 165 select GENERIC_IRQ_RESERVATION_MODE 166 select GENERIC_IRQ_SHOW 167 select GENERIC_PENDING_IRQ if SMP 168 select GENERIC_PTDUMP 169 select GENERIC_SMP_IDLE_THREAD 170 select GENERIC_TIME_VSYSCALL 171 select GENERIC_GETTIMEOFDAY 172 select GENERIC_VDSO_TIME_NS 173 select GENERIC_VDSO_OVERFLOW_PROTECT 174 select GUP_GET_PXX_LOW_HIGH if X86_PAE 175 select HARDIRQS_SW_RESEND 176 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 177 select HAS_IOPORT 178 select HAVE_ACPI_APEI if ACPI 179 select HAVE_ACPI_APEI_NMI if ACPI 180 select HAVE_ALIGNED_STRUCT_PAGE 181 select HAVE_ARCH_AUDITSYSCALL 182 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 183 select HAVE_ARCH_HUGE_VMALLOC if X86_64 184 select HAVE_ARCH_JUMP_LABEL 185 select HAVE_ARCH_JUMP_LABEL_RELATIVE 186 select HAVE_ARCH_KASAN if X86_64 187 select HAVE_ARCH_KASAN_VMALLOC if X86_64 188 select HAVE_ARCH_KFENCE 189 select HAVE_ARCH_KMSAN if X86_64 190 select HAVE_ARCH_KGDB 191 select HAVE_ARCH_MMAP_RND_BITS if MMU 192 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 193 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 194 select HAVE_ARCH_PREL32_RELOCATIONS 195 select HAVE_ARCH_SECCOMP_FILTER 196 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 197 select HAVE_ARCH_STACKLEAK 198 select HAVE_ARCH_TRACEHOOK 199 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 200 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 201 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 202 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 203 select HAVE_ARCH_VMAP_STACK if X86_64 204 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 205 select HAVE_ARCH_WITHIN_STACK_FRAMES 206 select HAVE_ASM_MODVERSIONS 207 select HAVE_CMPXCHG_DOUBLE 208 select HAVE_CMPXCHG_LOCAL 209 select HAVE_CONTEXT_TRACKING_USER if X86_64 210 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 211 select HAVE_C_RECORDMCOUNT 212 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 213 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 214 select HAVE_BUILDTIME_MCOUNT_SORT 215 select HAVE_DEBUG_KMEMLEAK 216 select HAVE_DMA_CONTIGUOUS 217 select HAVE_DYNAMIC_FTRACE 218 select HAVE_DYNAMIC_FTRACE_WITH_REGS 219 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 220 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 221 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 222 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 223 select HAVE_EBPF_JIT 224 select HAVE_EFFICIENT_UNALIGNED_ACCESS 225 select HAVE_EISA 226 select HAVE_EXIT_THREAD 227 select HAVE_GUP_FAST 228 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 229 select HAVE_FTRACE_MCOUNT_RECORD 230 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 231 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 232 select HAVE_FUNCTION_TRACER 233 select HAVE_GCC_PLUGINS 234 select HAVE_HW_BREAKPOINT 235 select HAVE_IOREMAP_PROT 236 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 237 select HAVE_IRQ_TIME_ACCOUNTING 238 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 239 select HAVE_KERNEL_BZIP2 240 select HAVE_KERNEL_GZIP 241 select HAVE_KERNEL_LZ4 242 select HAVE_KERNEL_LZMA 243 select HAVE_KERNEL_LZO 244 select HAVE_KERNEL_XZ 245 select HAVE_KERNEL_ZSTD 246 select HAVE_KPROBES 247 select HAVE_KPROBES_ON_FTRACE 248 select HAVE_FUNCTION_ERROR_INJECTION 249 select HAVE_KRETPROBES 250 select HAVE_RETHOOK 251 select HAVE_LIVEPATCH if X86_64 252 select HAVE_MIXED_BREAKPOINTS_REGS 253 select HAVE_MOD_ARCH_SPECIFIC 254 select HAVE_MOVE_PMD 255 select HAVE_MOVE_PUD 256 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 257 select HAVE_NMI 258 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 259 select HAVE_OBJTOOL if X86_64 260 select HAVE_OPTPROBES 261 select HAVE_PAGE_SIZE_4KB 262 select HAVE_PCSPKR_PLATFORM 263 select HAVE_PERF_EVENTS 264 select HAVE_PERF_EVENTS_NMI 265 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 266 select HAVE_PCI 267 select HAVE_PERF_REGS 268 select HAVE_PERF_USER_STACK_DUMP 269 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 270 select MMU_GATHER_MERGE_VMAS 271 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 272 select HAVE_REGS_AND_STACK_ACCESS_API 273 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 274 select HAVE_FUNCTION_ARG_ACCESS_API 275 select HAVE_SETUP_PER_CPU_AREA 276 select HAVE_SOFTIRQ_ON_OWN_STACK 277 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 278 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 279 select HAVE_STATIC_CALL 280 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 281 select HAVE_PREEMPT_DYNAMIC_CALL 282 select HAVE_RSEQ 283 select HAVE_RUST if X86_64 284 select HAVE_SYSCALL_TRACEPOINTS 285 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 286 select HAVE_UNSTABLE_SCHED_CLOCK 287 select HAVE_USER_RETURN_NOTIFIER 288 select HAVE_GENERIC_VDSO 289 select HOTPLUG_PARALLEL if SMP && X86_64 290 select HOTPLUG_SMT if SMP 291 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 292 select IRQ_FORCED_THREADING 293 select LOCK_MM_AND_FIND_VMA 294 select NEED_PER_CPU_EMBED_FIRST_CHUNK 295 select NEED_PER_CPU_PAGE_FIRST_CHUNK 296 select NEED_SG_DMA_LENGTH 297 select PCI_DOMAINS if PCI 298 select PCI_LOCKLESS_CONFIG if PCI 299 select PERF_EVENTS 300 select RTC_LIB 301 select RTC_MC146818_LIB 302 select SPARSE_IRQ 303 select SYSCTL_EXCEPTION_TRACE 304 select THREAD_INFO_IN_TASK 305 select TRACE_IRQFLAGS_SUPPORT 306 select TRACE_IRQFLAGS_NMI_SUPPORT 307 select USER_STACKTRACE_SUPPORT 308 select HAVE_ARCH_KCSAN if X86_64 309 select PROC_PID_ARCH_STATUS if PROC_FS 310 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 311 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 312 select FUNCTION_ALIGNMENT_4B 313 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 314 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 315 316config INSTRUCTION_DECODER 317 def_bool y 318 depends on KPROBES || PERF_EVENTS || UPROBES 319 320config OUTPUT_FORMAT 321 string 322 default "elf32-i386" if X86_32 323 default "elf64-x86-64" if X86_64 324 325config LOCKDEP_SUPPORT 326 def_bool y 327 328config STACKTRACE_SUPPORT 329 def_bool y 330 331config MMU 332 def_bool y 333 334config ARCH_MMAP_RND_BITS_MIN 335 default 28 if 64BIT 336 default 8 337 338config ARCH_MMAP_RND_BITS_MAX 339 default 32 if 64BIT 340 default 16 341 342config ARCH_MMAP_RND_COMPAT_BITS_MIN 343 default 8 344 345config ARCH_MMAP_RND_COMPAT_BITS_MAX 346 default 16 347 348config SBUS 349 bool 350 351config GENERIC_ISA_DMA 352 def_bool y 353 depends on ISA_DMA_API 354 355config GENERIC_CSUM 356 bool 357 default y if KMSAN || KASAN 358 359config GENERIC_BUG 360 def_bool y 361 depends on BUG 362 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 363 364config GENERIC_BUG_RELATIVE_POINTERS 365 bool 366 367config ARCH_MAY_HAVE_PC_FDC 368 def_bool y 369 depends on ISA_DMA_API 370 371config GENERIC_CALIBRATE_DELAY 372 def_bool y 373 374config ARCH_HAS_CPU_RELAX 375 def_bool y 376 377config ARCH_HIBERNATION_POSSIBLE 378 def_bool y 379 380config ARCH_SUSPEND_POSSIBLE 381 def_bool y 382 383config AUDIT_ARCH 384 def_bool y if X86_64 385 386config KASAN_SHADOW_OFFSET 387 hex 388 depends on KASAN 389 default 0xdffffc0000000000 390 391config HAVE_INTEL_TXT 392 def_bool y 393 depends on INTEL_IOMMU && ACPI 394 395config X86_64_SMP 396 def_bool y 397 depends on X86_64 && SMP 398 399config ARCH_SUPPORTS_UPROBES 400 def_bool y 401 402config FIX_EARLYCON_MEM 403 def_bool y 404 405config DYNAMIC_PHYSICAL_MASK 406 bool 407 408config PGTABLE_LEVELS 409 int 410 default 5 if X86_5LEVEL 411 default 4 if X86_64 412 default 3 if X86_PAE 413 default 2 414 415config CC_HAS_SANE_STACKPROTECTOR 416 bool 417 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 418 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 419 help 420 We have to make sure stack protector is unconditionally disabled if 421 the compiler produces broken code or if it does not let us control 422 the segment on 32-bit kernels. 423 424menu "Processor type and features" 425 426config SMP 427 bool "Symmetric multi-processing support" 428 help 429 This enables support for systems with more than one CPU. If you have 430 a system with only one CPU, say N. If you have a system with more 431 than one CPU, say Y. 432 433 If you say N here, the kernel will run on uni- and multiprocessor 434 machines, but will use only one CPU of a multiprocessor machine. If 435 you say Y here, the kernel will run on many, but not all, 436 uniprocessor machines. On a uniprocessor machine, the kernel 437 will run faster if you say N here. 438 439 Note that if you say Y here and choose architecture "586" or 440 "Pentium" under "Processor family", the kernel will not work on 486 441 architectures. Similarly, multiprocessor kernels for the "PPro" 442 architecture may not work on all Pentium based boards. 443 444 People using multiprocessor machines who say Y here should also say 445 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 446 Management" code will be disabled if you say Y here. 447 448 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 449 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 450 <http://www.tldp.org/docs.html#howto>. 451 452 If you don't know what to do here, say N. 453 454config X86_X2APIC 455 bool "Support x2apic" 456 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 457 help 458 This enables x2apic support on CPUs that have this feature. 459 460 This allows 32-bit apic IDs (so it can support very large systems), 461 and accesses the local apic via MSRs not via mmio. 462 463 Some Intel systems circa 2022 and later are locked into x2APIC mode 464 and can not fall back to the legacy APIC modes if SGX or TDX are 465 enabled in the BIOS. They will boot with very reduced functionality 466 without enabling this option. 467 468 If you don't know what to do here, say N. 469 470config X86_POSTED_MSI 471 bool "Enable MSI and MSI-x delivery by posted interrupts" 472 depends on X86_64 && IRQ_REMAP 473 help 474 This enables MSIs that are under interrupt remapping to be delivered as 475 posted interrupts to the host kernel. Interrupt throughput can 476 potentially be improved by coalescing CPU notifications during high 477 frequency bursts. 478 479 If you don't know what to do here, say N. 480 481config X86_MPPARSE 482 bool "Enable MPS table" if ACPI 483 default y 484 depends on X86_LOCAL_APIC 485 help 486 For old smp systems that do not have proper acpi support. Newer systems 487 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 488 489config X86_CPU_RESCTRL 490 bool "x86 CPU resource control support" 491 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 492 select KERNFS 493 select PROC_CPU_RESCTRL if PROC_FS 494 help 495 Enable x86 CPU resource control support. 496 497 Provide support for the allocation and monitoring of system resources 498 usage by the CPU. 499 500 Intel calls this Intel Resource Director Technology 501 (Intel(R) RDT). More information about RDT can be found in the 502 Intel x86 Architecture Software Developer Manual. 503 504 AMD calls this AMD Platform Quality of Service (AMD QoS). 505 More information about AMD QoS can be found in the AMD64 Technology 506 Platform Quality of Service Extensions manual. 507 508 Say N if unsure. 509 510config X86_FRED 511 bool "Flexible Return and Event Delivery" 512 depends on X86_64 513 help 514 When enabled, try to use Flexible Return and Event Delivery 515 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 516 ring transitions and exception/interrupt handling if the 517 system supports it. 518 519config X86_BIGSMP 520 bool "Support for big SMP systems with more than 8 CPUs" 521 depends on SMP && X86_32 522 help 523 This option is needed for the systems that have more than 8 CPUs. 524 525config X86_EXTENDED_PLATFORM 526 bool "Support for extended (non-PC) x86 platforms" 527 default y 528 help 529 If you disable this option then the kernel will only support 530 standard PC platforms. (which covers the vast majority of 531 systems out there.) 532 533 If you enable this option then you'll be able to select support 534 for the following non-PC x86 platforms, depending on the value of 535 CONFIG_64BIT. 536 537 32-bit platforms (CONFIG_64BIT=n): 538 Goldfish (Android emulator) 539 AMD Elan 540 RDC R-321x SoC 541 SGI 320/540 (Visual Workstation) 542 STA2X11-based (e.g. Northville) 543 Moorestown MID devices 544 545 64-bit platforms (CONFIG_64BIT=y): 546 Numascale NumaChip 547 ScaleMP vSMP 548 SGI Ultraviolet 549 550 If you have one of these systems, or if you want to build a 551 generic distribution kernel, say Y here - otherwise say N. 552 553# This is an alphabetically sorted list of 64 bit extended platforms 554# Please maintain the alphabetic order if and when there are additions 555config X86_NUMACHIP 556 bool "Numascale NumaChip" 557 depends on X86_64 558 depends on X86_EXTENDED_PLATFORM 559 depends on NUMA 560 depends on SMP 561 depends on X86_X2APIC 562 depends on PCI_MMCONFIG 563 help 564 Adds support for Numascale NumaChip large-SMP systems. Needed to 565 enable more than ~168 cores. 566 If you don't have one of these, you should say N here. 567 568config X86_VSMP 569 bool "ScaleMP vSMP" 570 select HYPERVISOR_GUEST 571 select PARAVIRT 572 depends on X86_64 && PCI 573 depends on X86_EXTENDED_PLATFORM 574 depends on SMP 575 help 576 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 577 supposed to run on these EM64T-based machines. Only choose this option 578 if you have one of these machines. 579 580config X86_UV 581 bool "SGI Ultraviolet" 582 depends on X86_64 583 depends on X86_EXTENDED_PLATFORM 584 depends on NUMA 585 depends on EFI 586 depends on KEXEC_CORE 587 depends on X86_X2APIC 588 depends on PCI 589 help 590 This option is needed in order to support SGI Ultraviolet systems. 591 If you don't have one of these, you should say N here. 592 593# Following is an alphabetically sorted list of 32 bit extended platforms 594# Please maintain the alphabetic order if and when there are additions 595 596config X86_GOLDFISH 597 bool "Goldfish (Virtual Platform)" 598 depends on X86_EXTENDED_PLATFORM 599 help 600 Enable support for the Goldfish virtual platform used primarily 601 for Android development. Unless you are building for the Android 602 Goldfish emulator say N here. 603 604config X86_INTEL_CE 605 bool "CE4100 TV platform" 606 depends on PCI 607 depends on PCI_GODIRECT 608 depends on X86_IO_APIC 609 depends on X86_32 610 depends on X86_EXTENDED_PLATFORM 611 select X86_REBOOTFIXUPS 612 select OF 613 select OF_EARLY_FLATTREE 614 help 615 Select for the Intel CE media processor (CE4100) SOC. 616 This option compiles in support for the CE4100 SOC for settop 617 boxes and media devices. 618 619config X86_INTEL_MID 620 bool "Intel MID platform support" 621 depends on X86_EXTENDED_PLATFORM 622 depends on X86_PLATFORM_DEVICES 623 depends on PCI 624 depends on X86_64 || (PCI_GOANY && X86_32) 625 depends on X86_IO_APIC 626 select I2C 627 select DW_APB_TIMER 628 select INTEL_SCU_PCI 629 help 630 Select to build a kernel capable of supporting Intel MID (Mobile 631 Internet Device) platform systems which do not have the PCI legacy 632 interfaces. If you are building for a PC class system say N here. 633 634 Intel MID platforms are based on an Intel processor and chipset which 635 consume less power than most of the x86 derivatives. 636 637config X86_INTEL_QUARK 638 bool "Intel Quark platform support" 639 depends on X86_32 640 depends on X86_EXTENDED_PLATFORM 641 depends on X86_PLATFORM_DEVICES 642 depends on X86_TSC 643 depends on PCI 644 depends on PCI_GOANY 645 depends on X86_IO_APIC 646 select IOSF_MBI 647 select INTEL_IMR 648 select COMMON_CLK 649 help 650 Select to include support for Quark X1000 SoC. 651 Say Y here if you have a Quark based system such as the Arduino 652 compatible Intel Galileo. 653 654config X86_INTEL_LPSS 655 bool "Intel Low Power Subsystem Support" 656 depends on X86 && ACPI && PCI 657 select COMMON_CLK 658 select PINCTRL 659 select IOSF_MBI 660 help 661 Select to build support for Intel Low Power Subsystem such as 662 found on Intel Lynxpoint PCH. Selecting this option enables 663 things like clock tree (common clock framework) and pincontrol 664 which are needed by the LPSS peripheral drivers. 665 666config X86_AMD_PLATFORM_DEVICE 667 bool "AMD ACPI2Platform devices support" 668 depends on ACPI 669 select COMMON_CLK 670 select PINCTRL 671 help 672 Select to interpret AMD specific ACPI device to platform device 673 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 674 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 675 implemented under PINCTRL subsystem. 676 677config IOSF_MBI 678 tristate "Intel SoC IOSF Sideband support for SoC platforms" 679 depends on PCI 680 help 681 This option enables sideband register access support for Intel SoC 682 platforms. On these platforms the IOSF sideband is used in lieu of 683 MSR's for some register accesses, mostly but not limited to thermal 684 and power. Drivers may query the availability of this device to 685 determine if they need the sideband in order to work on these 686 platforms. The sideband is available on the following SoC products. 687 This list is not meant to be exclusive. 688 - BayTrail 689 - Braswell 690 - Quark 691 692 You should say Y if you are running a kernel on one of these SoC's. 693 694config IOSF_MBI_DEBUG 695 bool "Enable IOSF sideband access through debugfs" 696 depends on IOSF_MBI && DEBUG_FS 697 help 698 Select this option to expose the IOSF sideband access registers (MCR, 699 MDR, MCRX) through debugfs to write and read register information from 700 different units on the SoC. This is most useful for obtaining device 701 state information for debug and analysis. As this is a general access 702 mechanism, users of this option would have specific knowledge of the 703 device they want to access. 704 705 If you don't require the option or are in doubt, say N. 706 707config X86_RDC321X 708 bool "RDC R-321x SoC" 709 depends on X86_32 710 depends on X86_EXTENDED_PLATFORM 711 select M486 712 select X86_REBOOTFIXUPS 713 help 714 This option is needed for RDC R-321x system-on-chip, also known 715 as R-8610-(G). 716 If you don't have one of these chips, you should say N here. 717 718config X86_32_NON_STANDARD 719 bool "Support non-standard 32-bit SMP architectures" 720 depends on X86_32 && SMP 721 depends on X86_EXTENDED_PLATFORM 722 help 723 This option compiles in the bigsmp and STA2X11 default 724 subarchitectures. It is intended for a generic binary 725 kernel. If you select them all, kernel will probe it one by 726 one and will fallback to default. 727 728# Alphabetically sorted list of Non standard 32 bit platforms 729 730config X86_SUPPORTS_MEMORY_FAILURE 731 def_bool y 732 # MCE code calls memory_failure(): 733 depends on X86_MCE 734 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 735 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 736 depends on X86_64 || !SPARSEMEM 737 select ARCH_SUPPORTS_MEMORY_FAILURE 738 739config STA2X11 740 bool "STA2X11 Companion Chip Support" 741 depends on X86_32_NON_STANDARD && PCI 742 select SWIOTLB 743 select MFD_STA2X11 744 select GPIOLIB 745 help 746 This adds support for boards based on the STA2X11 IO-Hub, 747 a.k.a. "ConneXt". The chip is used in place of the standard 748 PC chipset, so all "standard" peripherals are missing. If this 749 option is selected the kernel will still be able to boot on 750 standard PC machines. 751 752config X86_32_IRIS 753 tristate "Eurobraille/Iris poweroff module" 754 depends on X86_32 755 help 756 The Iris machines from EuroBraille do not have APM or ACPI support 757 to shut themselves down properly. A special I/O sequence is 758 needed to do so, which is what this module does at 759 kernel shutdown. 760 761 This is only for Iris machines from EuroBraille. 762 763 If unused, say N. 764 765config SCHED_OMIT_FRAME_POINTER 766 def_bool y 767 prompt "Single-depth WCHAN output" 768 depends on X86 769 help 770 Calculate simpler /proc/<PID>/wchan values. If this option 771 is disabled then wchan values will recurse back to the 772 caller function. This provides more accurate wchan values, 773 at the expense of slightly more scheduling overhead. 774 775 If in doubt, say "Y". 776 777menuconfig HYPERVISOR_GUEST 778 bool "Linux guest support" 779 help 780 Say Y here to enable options for running Linux under various hyper- 781 visors. This option enables basic hypervisor detection and platform 782 setup. 783 784 If you say N, all options in this submenu will be skipped and 785 disabled, and Linux guest support won't be built in. 786 787if HYPERVISOR_GUEST 788 789config PARAVIRT 790 bool "Enable paravirtualization code" 791 depends on HAVE_STATIC_CALL 792 help 793 This changes the kernel so it can modify itself when it is run 794 under a hypervisor, potentially improving performance significantly 795 over full virtualization. However, when run without a hypervisor 796 the kernel is theoretically slower and slightly larger. 797 798config PARAVIRT_XXL 799 bool 800 801config PARAVIRT_DEBUG 802 bool "paravirt-ops debugging" 803 depends on PARAVIRT && DEBUG_KERNEL 804 help 805 Enable to debug paravirt_ops internals. Specifically, BUG if 806 a paravirt_op is missing when it is called. 807 808config PARAVIRT_SPINLOCKS 809 bool "Paravirtualization layer for spinlocks" 810 depends on PARAVIRT && SMP 811 help 812 Paravirtualized spinlocks allow a pvops backend to replace the 813 spinlock implementation with something virtualization-friendly 814 (for example, block the virtual CPU rather than spinning). 815 816 It has a minimal impact on native kernels and gives a nice performance 817 benefit on paravirtualized KVM / Xen kernels. 818 819 If you are unsure how to answer this question, answer Y. 820 821config X86_HV_CALLBACK_VECTOR 822 def_bool n 823 824source "arch/x86/xen/Kconfig" 825 826config KVM_GUEST 827 bool "KVM Guest support (including kvmclock)" 828 depends on PARAVIRT 829 select PARAVIRT_CLOCK 830 select ARCH_CPUIDLE_HALTPOLL 831 select X86_HV_CALLBACK_VECTOR 832 default y 833 help 834 This option enables various optimizations for running under the KVM 835 hypervisor. It includes a paravirtualized clock, so that instead 836 of relying on a PIT (or probably other) emulation by the 837 underlying device model, the host provides the guest with 838 timing infrastructure such as time of day, and system time 839 840config ARCH_CPUIDLE_HALTPOLL 841 def_bool n 842 prompt "Disable host haltpoll when loading haltpoll driver" 843 help 844 If virtualized under KVM, disable host haltpoll. 845 846config PVH 847 bool "Support for running PVH guests" 848 help 849 This option enables the PVH entry point for guest virtual machines 850 as specified in the x86/HVM direct boot ABI. 851 852config PARAVIRT_TIME_ACCOUNTING 853 bool "Paravirtual steal time accounting" 854 depends on PARAVIRT 855 help 856 Select this option to enable fine granularity task steal time 857 accounting. Time spent executing other tasks in parallel with 858 the current vCPU is discounted from the vCPU power. To account for 859 that, there can be a small performance impact. 860 861 If in doubt, say N here. 862 863config PARAVIRT_CLOCK 864 bool 865 866config JAILHOUSE_GUEST 867 bool "Jailhouse non-root cell support" 868 depends on X86_64 && PCI 869 select X86_PM_TIMER 870 help 871 This option allows to run Linux as guest in a Jailhouse non-root 872 cell. You can leave this option disabled if you only want to start 873 Jailhouse and run Linux afterwards in the root cell. 874 875config ACRN_GUEST 876 bool "ACRN Guest support" 877 depends on X86_64 878 select X86_HV_CALLBACK_VECTOR 879 help 880 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 881 a flexible, lightweight reference open-source hypervisor, built with 882 real-time and safety-criticality in mind. It is built for embedded 883 IOT with small footprint and real-time features. More details can be 884 found in https://projectacrn.org/. 885 886config INTEL_TDX_GUEST 887 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 888 depends on X86_64 && CPU_SUP_INTEL 889 depends on X86_X2APIC 890 depends on EFI_STUB 891 select ARCH_HAS_CC_PLATFORM 892 select X86_MEM_ENCRYPT 893 select X86_MCE 894 select UNACCEPTED_MEMORY 895 help 896 Support running as a guest under Intel TDX. Without this support, 897 the guest kernel can not boot or run under TDX. 898 TDX includes memory encryption and integrity capabilities 899 which protect the confidentiality and integrity of guest 900 memory contents and CPU state. TDX guests are protected from 901 some attacks from the VMM. 902 903endif # HYPERVISOR_GUEST 904 905source "arch/x86/Kconfig.cpu" 906 907config HPET_TIMER 908 def_bool X86_64 909 prompt "HPET Timer Support" if X86_32 910 help 911 Use the IA-PC HPET (High Precision Event Timer) to manage 912 time in preference to the PIT and RTC, if a HPET is 913 present. 914 HPET is the next generation timer replacing legacy 8254s. 915 The HPET provides a stable time base on SMP 916 systems, unlike the TSC, but it is more expensive to access, 917 as it is off-chip. The interface used is documented 918 in the HPET spec, revision 1. 919 920 You can safely choose Y here. However, HPET will only be 921 activated if the platform and the BIOS support this feature. 922 Otherwise the 8254 will be used for timing services. 923 924 Choose N to continue using the legacy 8254 timer. 925 926config HPET_EMULATE_RTC 927 def_bool y 928 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 929 930# Mark as expert because too many people got it wrong. 931# The code disables itself when not needed. 932config DMI 933 default y 934 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 935 bool "Enable DMI scanning" if EXPERT 936 help 937 Enabled scanning of DMI to identify machine quirks. Say Y 938 here unless you have verified that your setup is not 939 affected by entries in the DMI blacklist. Required by PNP 940 BIOS code. 941 942config GART_IOMMU 943 bool "Old AMD GART IOMMU support" 944 select DMA_OPS 945 select IOMMU_HELPER 946 select SWIOTLB 947 depends on X86_64 && PCI && AMD_NB 948 help 949 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 950 GART based hardware IOMMUs. 951 952 The GART supports full DMA access for devices with 32-bit access 953 limitations, on systems with more than 3 GB. This is usually needed 954 for USB, sound, many IDE/SATA chipsets and some other devices. 955 956 Newer systems typically have a modern AMD IOMMU, supported via 957 the CONFIG_AMD_IOMMU=y config option. 958 959 In normal configurations this driver is only active when needed: 960 there's more than 3 GB of memory and the system contains a 961 32-bit limited device. 962 963 If unsure, say Y. 964 965config BOOT_VESA_SUPPORT 966 bool 967 help 968 If true, at least one selected framebuffer driver can take advantage 969 of VESA video modes set at an early boot stage via the vga= parameter. 970 971config MAXSMP 972 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 973 depends on X86_64 && SMP && DEBUG_KERNEL 974 select CPUMASK_OFFSTACK 975 help 976 Enable maximum number of CPUS and NUMA Nodes for this architecture. 977 If unsure, say N. 978 979# 980# The maximum number of CPUs supported: 981# 982# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 983# and which can be configured interactively in the 984# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 985# 986# The ranges are different on 32-bit and 64-bit kernels, depending on 987# hardware capabilities and scalability features of the kernel. 988# 989# ( If MAXSMP is enabled we just use the highest possible value and disable 990# interactive configuration. ) 991# 992 993config NR_CPUS_RANGE_BEGIN 994 int 995 default NR_CPUS_RANGE_END if MAXSMP 996 default 1 if !SMP 997 default 2 998 999config NR_CPUS_RANGE_END 1000 int 1001 depends on X86_32 1002 default 64 if SMP && X86_BIGSMP 1003 default 8 if SMP && !X86_BIGSMP 1004 default 1 if !SMP 1005 1006config NR_CPUS_RANGE_END 1007 int 1008 depends on X86_64 1009 default 8192 if SMP && CPUMASK_OFFSTACK 1010 default 512 if SMP && !CPUMASK_OFFSTACK 1011 default 1 if !SMP 1012 1013config NR_CPUS_DEFAULT 1014 int 1015 depends on X86_32 1016 default 32 if X86_BIGSMP 1017 default 8 if SMP 1018 default 1 if !SMP 1019 1020config NR_CPUS_DEFAULT 1021 int 1022 depends on X86_64 1023 default 8192 if MAXSMP 1024 default 64 if SMP 1025 default 1 if !SMP 1026 1027config NR_CPUS 1028 int "Maximum number of CPUs" if SMP && !MAXSMP 1029 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1030 default NR_CPUS_DEFAULT 1031 help 1032 This allows you to specify the maximum number of CPUs which this 1033 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1034 supported value is 8192, otherwise the maximum value is 512. The 1035 minimum value which makes sense is 2. 1036 1037 This is purely to save memory: each supported CPU adds about 8KB 1038 to the kernel image. 1039 1040config SCHED_CLUSTER 1041 bool "Cluster scheduler support" 1042 depends on SMP 1043 default y 1044 help 1045 Cluster scheduler support improves the CPU scheduler's decision 1046 making when dealing with machines that have clusters of CPUs. 1047 Cluster usually means a couple of CPUs which are placed closely 1048 by sharing mid-level caches, last-level cache tags or internal 1049 busses. 1050 1051config SCHED_SMT 1052 def_bool y if SMP 1053 1054config SCHED_MC 1055 def_bool y 1056 prompt "Multi-core scheduler support" 1057 depends on SMP 1058 help 1059 Multi-core scheduler support improves the CPU scheduler's decision 1060 making when dealing with multi-core CPU chips at a cost of slightly 1061 increased overhead in some places. If unsure say N here. 1062 1063config SCHED_MC_PRIO 1064 bool "CPU core priorities scheduler support" 1065 depends on SCHED_MC 1066 select X86_INTEL_PSTATE if CPU_SUP_INTEL 1067 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI 1068 select CPU_FREQ 1069 default y 1070 help 1071 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1072 core ordering determined at manufacturing time, which allows 1073 certain cores to reach higher turbo frequencies (when running 1074 single threaded workloads) than others. 1075 1076 Enabling this kernel feature teaches the scheduler about 1077 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1078 scheduler's CPU selection logic accordingly, so that higher 1079 overall system performance can be achieved. 1080 1081 This feature will have no effect on CPUs without this feature. 1082 1083 If unsure say Y here. 1084 1085config UP_LATE_INIT 1086 def_bool y 1087 depends on !SMP && X86_LOCAL_APIC 1088 1089config X86_UP_APIC 1090 bool "Local APIC support on uniprocessors" if !PCI_MSI 1091 default PCI_MSI 1092 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1093 help 1094 A local APIC (Advanced Programmable Interrupt Controller) is an 1095 integrated interrupt controller in the CPU. If you have a single-CPU 1096 system which has a processor with a local APIC, you can say Y here to 1097 enable and use it. If you say Y here even though your machine doesn't 1098 have a local APIC, then the kernel will still run with no slowdown at 1099 all. The local APIC supports CPU-generated self-interrupts (timer, 1100 performance counters), and the NMI watchdog which detects hard 1101 lockups. 1102 1103config X86_UP_IOAPIC 1104 bool "IO-APIC support on uniprocessors" 1105 depends on X86_UP_APIC 1106 help 1107 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1108 SMP-capable replacement for PC-style interrupt controllers. Most 1109 SMP systems and many recent uniprocessor systems have one. 1110 1111 If you have a single-CPU system with an IO-APIC, you can say Y here 1112 to use it. If you say Y here even though your machine doesn't have 1113 an IO-APIC, then the kernel will still run with no slowdown at all. 1114 1115config X86_LOCAL_APIC 1116 def_bool y 1117 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1118 select IRQ_DOMAIN_HIERARCHY 1119 1120config X86_IO_APIC 1121 def_bool y 1122 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1123 1124config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1125 bool "Reroute for broken boot IRQs" 1126 depends on X86_IO_APIC 1127 help 1128 This option enables a workaround that fixes a source of 1129 spurious interrupts. This is recommended when threaded 1130 interrupt handling is used on systems where the generation of 1131 superfluous "boot interrupts" cannot be disabled. 1132 1133 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1134 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1135 kernel does during interrupt handling). On chipsets where this 1136 boot IRQ generation cannot be disabled, this workaround keeps 1137 the original IRQ line masked so that only the equivalent "boot 1138 IRQ" is delivered to the CPUs. The workaround also tells the 1139 kernel to set up the IRQ handler on the boot IRQ line. In this 1140 way only one interrupt is delivered to the kernel. Otherwise 1141 the spurious second interrupt may cause the kernel to bring 1142 down (vital) interrupt lines. 1143 1144 Only affects "broken" chipsets. Interrupt sharing may be 1145 increased on these systems. 1146 1147config X86_MCE 1148 bool "Machine Check / overheating reporting" 1149 select GENERIC_ALLOCATOR 1150 default y 1151 help 1152 Machine Check support allows the processor to notify the 1153 kernel if it detects a problem (e.g. overheating, data corruption). 1154 The action the kernel takes depends on the severity of the problem, 1155 ranging from warning messages to halting the machine. 1156 1157config X86_MCELOG_LEGACY 1158 bool "Support for deprecated /dev/mcelog character device" 1159 depends on X86_MCE 1160 help 1161 Enable support for /dev/mcelog which is needed by the old mcelog 1162 userspace logging daemon. Consider switching to the new generation 1163 rasdaemon solution. 1164 1165config X86_MCE_INTEL 1166 def_bool y 1167 prompt "Intel MCE features" 1168 depends on X86_MCE && X86_LOCAL_APIC 1169 help 1170 Additional support for intel specific MCE features such as 1171 the thermal monitor. 1172 1173config X86_MCE_AMD 1174 def_bool y 1175 prompt "AMD MCE features" 1176 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1177 help 1178 Additional support for AMD specific MCE features such as 1179 the DRAM Error Threshold. 1180 1181config X86_ANCIENT_MCE 1182 bool "Support for old Pentium 5 / WinChip machine checks" 1183 depends on X86_32 && X86_MCE 1184 help 1185 Include support for machine check handling on old Pentium 5 or WinChip 1186 systems. These typically need to be enabled explicitly on the command 1187 line. 1188 1189config X86_MCE_THRESHOLD 1190 depends on X86_MCE_AMD || X86_MCE_INTEL 1191 def_bool y 1192 1193config X86_MCE_INJECT 1194 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1195 tristate "Machine check injector support" 1196 help 1197 Provide support for injecting machine checks for testing purposes. 1198 If you don't know what a machine check is and you don't do kernel 1199 QA it is safe to say n. 1200 1201source "arch/x86/events/Kconfig" 1202 1203config X86_LEGACY_VM86 1204 bool "Legacy VM86 support" 1205 depends on X86_32 1206 help 1207 This option allows user programs to put the CPU into V8086 1208 mode, which is an 80286-era approximation of 16-bit real mode. 1209 1210 Some very old versions of X and/or vbetool require this option 1211 for user mode setting. Similarly, DOSEMU will use it if 1212 available to accelerate real mode DOS programs. However, any 1213 recent version of DOSEMU, X, or vbetool should be fully 1214 functional even without kernel VM86 support, as they will all 1215 fall back to software emulation. Nevertheless, if you are using 1216 a 16-bit DOS program where 16-bit performance matters, vm86 1217 mode might be faster than emulation and you might want to 1218 enable this option. 1219 1220 Note that any app that works on a 64-bit kernel is unlikely to 1221 need this option, as 64-bit kernels don't, and can't, support 1222 V8086 mode. This option is also unrelated to 16-bit protected 1223 mode and is not needed to run most 16-bit programs under Wine. 1224 1225 Enabling this option increases the complexity of the kernel 1226 and slows down exception handling a tiny bit. 1227 1228 If unsure, say N here. 1229 1230config VM86 1231 bool 1232 default X86_LEGACY_VM86 1233 1234config X86_16BIT 1235 bool "Enable support for 16-bit segments" if EXPERT 1236 default y 1237 depends on MODIFY_LDT_SYSCALL 1238 help 1239 This option is required by programs like Wine to run 16-bit 1240 protected mode legacy code on x86 processors. Disabling 1241 this option saves about 300 bytes on i386, or around 6K text 1242 plus 16K runtime memory on x86-64, 1243 1244config X86_ESPFIX32 1245 def_bool y 1246 depends on X86_16BIT && X86_32 1247 1248config X86_ESPFIX64 1249 def_bool y 1250 depends on X86_16BIT && X86_64 1251 1252config X86_VSYSCALL_EMULATION 1253 bool "Enable vsyscall emulation" if EXPERT 1254 default y 1255 depends on X86_64 1256 help 1257 This enables emulation of the legacy vsyscall page. Disabling 1258 it is roughly equivalent to booting with vsyscall=none, except 1259 that it will also disable the helpful warning if a program 1260 tries to use a vsyscall. With this option set to N, offending 1261 programs will just segfault, citing addresses of the form 1262 0xffffffffff600?00. 1263 1264 This option is required by many programs built before 2013, and 1265 care should be used even with newer programs if set to N. 1266 1267 Disabling this option saves about 7K of kernel size and 1268 possibly 4K of additional runtime pagetable memory. 1269 1270config X86_IOPL_IOPERM 1271 bool "IOPERM and IOPL Emulation" 1272 default y 1273 help 1274 This enables the ioperm() and iopl() syscalls which are necessary 1275 for legacy applications. 1276 1277 Legacy IOPL support is an overbroad mechanism which allows user 1278 space aside of accessing all 65536 I/O ports also to disable 1279 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1280 capabilities and permission from potentially active security 1281 modules. 1282 1283 The emulation restricts the functionality of the syscall to 1284 only allowing the full range I/O port access, but prevents the 1285 ability to disable interrupts from user space which would be 1286 granted if the hardware IOPL mechanism would be used. 1287 1288config TOSHIBA 1289 tristate "Toshiba Laptop support" 1290 depends on X86_32 1291 help 1292 This adds a driver to safely access the System Management Mode of 1293 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1294 not work on models with a Phoenix BIOS. The System Management Mode 1295 is used to set the BIOS and power saving options on Toshiba portables. 1296 1297 For information on utilities to make use of this driver see the 1298 Toshiba Linux utilities web site at: 1299 <http://www.buzzard.org.uk/toshiba/>. 1300 1301 Say Y if you intend to run this kernel on a Toshiba portable. 1302 Say N otherwise. 1303 1304config X86_REBOOTFIXUPS 1305 bool "Enable X86 board specific fixups for reboot" 1306 depends on X86_32 1307 help 1308 This enables chipset and/or board specific fixups to be done 1309 in order to get reboot to work correctly. This is only needed on 1310 some combinations of hardware and BIOS. The symptom, for which 1311 this config is intended, is when reboot ends with a stalled/hung 1312 system. 1313 1314 Currently, the only fixup is for the Geode machines using 1315 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1316 1317 Say Y if you want to enable the fixup. Currently, it's safe to 1318 enable this option even if you don't need it. 1319 Say N otherwise. 1320 1321config MICROCODE 1322 def_bool y 1323 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1324 1325config MICROCODE_INITRD32 1326 def_bool y 1327 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1328 1329config MICROCODE_LATE_LOADING 1330 bool "Late microcode loading (DANGEROUS)" 1331 default n 1332 depends on MICROCODE && SMP 1333 help 1334 Loading microcode late, when the system is up and executing instructions 1335 is a tricky business and should be avoided if possible. Just the sequence 1336 of synchronizing all cores and SMT threads is one fragile dance which does 1337 not guarantee that cores might not softlock after the loading. Therefore, 1338 use this at your own risk. Late loading taints the kernel unless the 1339 microcode header indicates that it is safe for late loading via the 1340 minimal revision check. This minimal revision check can be enforced on 1341 the kernel command line with "microcode.minrev=Y". 1342 1343config MICROCODE_LATE_FORCE_MINREV 1344 bool "Enforce late microcode loading minimal revision check" 1345 default n 1346 depends on MICROCODE_LATE_LOADING 1347 help 1348 To prevent that users load microcode late which modifies already 1349 in use features, newer microcode patches have a minimum revision field 1350 in the microcode header, which tells the kernel which minimum 1351 revision must be active in the CPU to safely load that new microcode 1352 late into the running system. If disabled the check will not 1353 be enforced but the kernel will be tainted when the minimal 1354 revision check fails. 1355 1356 This minimal revision check can also be controlled via the 1357 "microcode.minrev" parameter on the kernel command line. 1358 1359 If unsure say Y. 1360 1361config X86_MSR 1362 tristate "/dev/cpu/*/msr - Model-specific register support" 1363 help 1364 This device gives privileged processes access to the x86 1365 Model-Specific Registers (MSRs). It is a character device with 1366 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1367 MSR accesses are directed to a specific CPU on multi-processor 1368 systems. 1369 1370config X86_CPUID 1371 tristate "/dev/cpu/*/cpuid - CPU information support" 1372 help 1373 This device gives processes access to the x86 CPUID instruction to 1374 be executed on a specific processor. It is a character device 1375 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1376 /dev/cpu/31/cpuid. 1377 1378choice 1379 prompt "High Memory Support" 1380 default HIGHMEM4G 1381 depends on X86_32 1382 1383config NOHIGHMEM 1384 bool "off" 1385 help 1386 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1387 However, the address space of 32-bit x86 processors is only 4 1388 Gigabytes large. That means that, if you have a large amount of 1389 physical memory, not all of it can be "permanently mapped" by the 1390 kernel. The physical memory that's not permanently mapped is called 1391 "high memory". 1392 1393 If you are compiling a kernel which will never run on a machine with 1394 more than 1 Gigabyte total physical RAM, answer "off" here (default 1395 choice and suitable for most users). This will result in a "3GB/1GB" 1396 split: 3GB are mapped so that each process sees a 3GB virtual memory 1397 space and the remaining part of the 4GB virtual memory space is used 1398 by the kernel to permanently map as much physical memory as 1399 possible. 1400 1401 If the machine has between 1 and 4 Gigabytes physical RAM, then 1402 answer "4GB" here. 1403 1404 If more than 4 Gigabytes is used then answer "64GB" here. This 1405 selection turns Intel PAE (Physical Address Extension) mode on. 1406 PAE implements 3-level paging on IA32 processors. PAE is fully 1407 supported by Linux, PAE mode is implemented on all recent Intel 1408 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1409 then the kernel will not boot on CPUs that don't support PAE! 1410 1411 The actual amount of total physical memory will either be 1412 auto detected or can be forced by using a kernel command line option 1413 such as "mem=256M". (Try "man bootparam" or see the documentation of 1414 your boot loader (lilo or loadlin) about how to pass options to the 1415 kernel at boot time.) 1416 1417 If unsure, say "off". 1418 1419config HIGHMEM4G 1420 bool "4GB" 1421 help 1422 Select this if you have a 32-bit processor and between 1 and 4 1423 gigabytes of physical RAM. 1424 1425config HIGHMEM64G 1426 bool "64GB" 1427 depends on X86_HAVE_PAE 1428 select X86_PAE 1429 help 1430 Select this if you have a 32-bit processor and more than 4 1431 gigabytes of physical RAM. 1432 1433endchoice 1434 1435choice 1436 prompt "Memory split" if EXPERT 1437 default VMSPLIT_3G 1438 depends on X86_32 1439 help 1440 Select the desired split between kernel and user memory. 1441 1442 If the address range available to the kernel is less than the 1443 physical memory installed, the remaining memory will be available 1444 as "high memory". Accessing high memory is a little more costly 1445 than low memory, as it needs to be mapped into the kernel first. 1446 Note that increasing the kernel address space limits the range 1447 available to user programs, making the address space there 1448 tighter. Selecting anything other than the default 3G/1G split 1449 will also likely make your kernel incompatible with binary-only 1450 kernel modules. 1451 1452 If you are not absolutely sure what you are doing, leave this 1453 option alone! 1454 1455 config VMSPLIT_3G 1456 bool "3G/1G user/kernel split" 1457 config VMSPLIT_3G_OPT 1458 depends on !X86_PAE 1459 bool "3G/1G user/kernel split (for full 1G low memory)" 1460 config VMSPLIT_2G 1461 bool "2G/2G user/kernel split" 1462 config VMSPLIT_2G_OPT 1463 depends on !X86_PAE 1464 bool "2G/2G user/kernel split (for full 2G low memory)" 1465 config VMSPLIT_1G 1466 bool "1G/3G user/kernel split" 1467endchoice 1468 1469config PAGE_OFFSET 1470 hex 1471 default 0xB0000000 if VMSPLIT_3G_OPT 1472 default 0x80000000 if VMSPLIT_2G 1473 default 0x78000000 if VMSPLIT_2G_OPT 1474 default 0x40000000 if VMSPLIT_1G 1475 default 0xC0000000 1476 depends on X86_32 1477 1478config HIGHMEM 1479 def_bool y 1480 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1481 1482config X86_PAE 1483 bool "PAE (Physical Address Extension) Support" 1484 depends on X86_32 && X86_HAVE_PAE 1485 select PHYS_ADDR_T_64BIT 1486 select SWIOTLB 1487 help 1488 PAE is required for NX support, and furthermore enables 1489 larger swapspace support for non-overcommit purposes. It 1490 has the cost of more pagetable lookup overhead, and also 1491 consumes more pagetable space per process. 1492 1493config X86_5LEVEL 1494 bool "Enable 5-level page tables support" 1495 default y 1496 select DYNAMIC_MEMORY_LAYOUT 1497 select SPARSEMEM_VMEMMAP 1498 depends on X86_64 1499 help 1500 5-level paging enables access to larger address space: 1501 up to 128 PiB of virtual address space and 4 PiB of 1502 physical address space. 1503 1504 It will be supported by future Intel CPUs. 1505 1506 A kernel with the option enabled can be booted on machines that 1507 support 4- or 5-level paging. 1508 1509 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1510 information. 1511 1512 Say N if unsure. 1513 1514config X86_DIRECT_GBPAGES 1515 def_bool y 1516 depends on X86_64 1517 help 1518 Certain kernel features effectively disable kernel 1519 linear 1 GB mappings (even if the CPU otherwise 1520 supports them), so don't confuse the user by printing 1521 that we have them enabled. 1522 1523config X86_CPA_STATISTICS 1524 bool "Enable statistic for Change Page Attribute" 1525 depends on DEBUG_FS 1526 help 1527 Expose statistics about the Change Page Attribute mechanism, which 1528 helps to determine the effectiveness of preserving large and huge 1529 page mappings when mapping protections are changed. 1530 1531config X86_MEM_ENCRYPT 1532 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1533 select DYNAMIC_PHYSICAL_MASK 1534 def_bool n 1535 1536config AMD_MEM_ENCRYPT 1537 bool "AMD Secure Memory Encryption (SME) support" 1538 depends on X86_64 && CPU_SUP_AMD 1539 depends on EFI_STUB 1540 select DMA_COHERENT_POOL 1541 select ARCH_USE_MEMREMAP_PROT 1542 select INSTRUCTION_DECODER 1543 select ARCH_HAS_CC_PLATFORM 1544 select X86_MEM_ENCRYPT 1545 select UNACCEPTED_MEMORY 1546 help 1547 Say yes to enable support for the encryption of system memory. 1548 This requires an AMD processor that supports Secure Memory 1549 Encryption (SME). 1550 1551# Common NUMA Features 1552config NUMA 1553 bool "NUMA Memory Allocation and Scheduler Support" 1554 depends on SMP 1555 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1556 default y if X86_BIGSMP 1557 select USE_PERCPU_NUMA_NODE_ID 1558 select OF_NUMA if OF 1559 help 1560 Enable NUMA (Non-Uniform Memory Access) support. 1561 1562 The kernel will try to allocate memory used by a CPU on the 1563 local memory controller of the CPU and add some more 1564 NUMA awareness to the kernel. 1565 1566 For 64-bit this is recommended if the system is Intel Core i7 1567 (or later), AMD Opteron, or EM64T NUMA. 1568 1569 For 32-bit this is only needed if you boot a 32-bit 1570 kernel on a 64-bit NUMA platform. 1571 1572 Otherwise, you should say N. 1573 1574config AMD_NUMA 1575 def_bool y 1576 prompt "Old style AMD Opteron NUMA detection" 1577 depends on X86_64 && NUMA && PCI 1578 help 1579 Enable AMD NUMA node topology detection. You should say Y here if 1580 you have a multi processor AMD system. This uses an old method to 1581 read the NUMA configuration directly from the builtin Northbridge 1582 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1583 which also takes priority if both are compiled in. 1584 1585config X86_64_ACPI_NUMA 1586 def_bool y 1587 prompt "ACPI NUMA detection" 1588 depends on X86_64 && NUMA && ACPI && PCI 1589 select ACPI_NUMA 1590 help 1591 Enable ACPI SRAT based node topology detection. 1592 1593config NUMA_EMU 1594 bool "NUMA emulation" 1595 depends on NUMA 1596 help 1597 Enable NUMA emulation. A flat machine will be split 1598 into virtual nodes when booted with "numa=fake=N", where N is the 1599 number of nodes. This is only useful for debugging. 1600 1601config NODES_SHIFT 1602 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1603 range 1 10 1604 default "10" if MAXSMP 1605 default "6" if X86_64 1606 default "3" 1607 depends on NUMA 1608 help 1609 Specify the maximum number of NUMA Nodes available on the target 1610 system. Increases memory reserved to accommodate various tables. 1611 1612config ARCH_FLATMEM_ENABLE 1613 def_bool y 1614 depends on X86_32 && !NUMA 1615 1616config ARCH_SPARSEMEM_ENABLE 1617 def_bool y 1618 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1619 select SPARSEMEM_STATIC if X86_32 1620 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1621 1622config ARCH_SPARSEMEM_DEFAULT 1623 def_bool X86_64 || (NUMA && X86_32) 1624 1625config ARCH_SELECT_MEMORY_MODEL 1626 def_bool y 1627 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1628 1629config ARCH_MEMORY_PROBE 1630 bool "Enable sysfs memory/probe interface" 1631 depends on MEMORY_HOTPLUG 1632 help 1633 This option enables a sysfs memory/probe interface for testing. 1634 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1635 If you are unsure how to answer this question, answer N. 1636 1637config ARCH_PROC_KCORE_TEXT 1638 def_bool y 1639 depends on X86_64 && PROC_KCORE 1640 1641config ILLEGAL_POINTER_VALUE 1642 hex 1643 default 0 if X86_32 1644 default 0xdead000000000000 if X86_64 1645 1646config X86_PMEM_LEGACY_DEVICE 1647 bool 1648 1649config X86_PMEM_LEGACY 1650 tristate "Support non-standard NVDIMMs and ADR protected memory" 1651 depends on PHYS_ADDR_T_64BIT 1652 depends on BLK_DEV 1653 select X86_PMEM_LEGACY_DEVICE 1654 select NUMA_KEEP_MEMINFO if NUMA 1655 select LIBNVDIMM 1656 help 1657 Treat memory marked using the non-standard e820 type of 12 as used 1658 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1659 The kernel will offer these regions to the 'pmem' driver so 1660 they can be used for persistent storage. 1661 1662 Say Y if unsure. 1663 1664config HIGHPTE 1665 bool "Allocate 3rd-level pagetables from highmem" 1666 depends on HIGHMEM 1667 help 1668 The VM uses one page table entry for each page of physical memory. 1669 For systems with a lot of RAM, this can be wasteful of precious 1670 low memory. Setting this option will put user-space page table 1671 entries in high memory. 1672 1673config X86_CHECK_BIOS_CORRUPTION 1674 bool "Check for low memory corruption" 1675 help 1676 Periodically check for memory corruption in low memory, which 1677 is suspected to be caused by BIOS. Even when enabled in the 1678 configuration, it is disabled at runtime. Enable it by 1679 setting "memory_corruption_check=1" on the kernel command 1680 line. By default it scans the low 64k of memory every 60 1681 seconds; see the memory_corruption_check_size and 1682 memory_corruption_check_period parameters in 1683 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1684 1685 When enabled with the default parameters, this option has 1686 almost no overhead, as it reserves a relatively small amount 1687 of memory and scans it infrequently. It both detects corruption 1688 and prevents it from affecting the running system. 1689 1690 It is, however, intended as a diagnostic tool; if repeatable 1691 BIOS-originated corruption always affects the same memory, 1692 you can use memmap= to prevent the kernel from using that 1693 memory. 1694 1695config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1696 bool "Set the default setting of memory_corruption_check" 1697 depends on X86_CHECK_BIOS_CORRUPTION 1698 default y 1699 help 1700 Set whether the default state of memory_corruption_check is 1701 on or off. 1702 1703config MATH_EMULATION 1704 bool 1705 depends on MODIFY_LDT_SYSCALL 1706 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1707 help 1708 Linux can emulate a math coprocessor (used for floating point 1709 operations) if you don't have one. 486DX and Pentium processors have 1710 a math coprocessor built in, 486SX and 386 do not, unless you added 1711 a 487DX or 387, respectively. (The messages during boot time can 1712 give you some hints here ["man dmesg"].) Everyone needs either a 1713 coprocessor or this emulation. 1714 1715 If you don't have a math coprocessor, you need to say Y here; if you 1716 say Y here even though you have a coprocessor, the coprocessor will 1717 be used nevertheless. (This behavior can be changed with the kernel 1718 command line option "no387", which comes handy if your coprocessor 1719 is broken. Try "man bootparam" or see the documentation of your boot 1720 loader (lilo or loadlin) about how to pass options to the kernel at 1721 boot time.) This means that it is a good idea to say Y here if you 1722 intend to use this kernel on different machines. 1723 1724 More information about the internals of the Linux math coprocessor 1725 emulation can be found in <file:arch/x86/math-emu/README>. 1726 1727 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1728 kernel, it won't hurt. 1729 1730config MTRR 1731 def_bool y 1732 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1733 help 1734 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1735 the Memory Type Range Registers (MTRRs) may be used to control 1736 processor access to memory ranges. This is most useful if you have 1737 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1738 allows bus write transfers to be combined into a larger transfer 1739 before bursting over the PCI/AGP bus. This can increase performance 1740 of image write operations 2.5 times or more. Saying Y here creates a 1741 /proc/mtrr file which may be used to manipulate your processor's 1742 MTRRs. Typically the X server should use this. 1743 1744 This code has a reasonably generic interface so that similar 1745 control registers on other processors can be easily supported 1746 as well: 1747 1748 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1749 Registers (ARRs) which provide a similar functionality to MTRRs. For 1750 these, the ARRs are used to emulate the MTRRs. 1751 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1752 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1753 write-combining. All of these processors are supported by this code 1754 and it makes sense to say Y here if you have one of them. 1755 1756 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1757 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1758 can lead to all sorts of problems, so it's good to say Y here. 1759 1760 You can safely say Y even if your machine doesn't have MTRRs, you'll 1761 just add about 9 KB to your kernel. 1762 1763 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1764 1765config MTRR_SANITIZER 1766 def_bool y 1767 prompt "MTRR cleanup support" 1768 depends on MTRR 1769 help 1770 Convert MTRR layout from continuous to discrete, so X drivers can 1771 add writeback entries. 1772 1773 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1774 The largest mtrr entry size for a continuous block can be set with 1775 mtrr_chunk_size. 1776 1777 If unsure, say Y. 1778 1779config MTRR_SANITIZER_ENABLE_DEFAULT 1780 int "MTRR cleanup enable value (0-1)" 1781 range 0 1 1782 default "0" 1783 depends on MTRR_SANITIZER 1784 help 1785 Enable mtrr cleanup default value 1786 1787config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1788 int "MTRR cleanup spare reg num (0-7)" 1789 range 0 7 1790 default "1" 1791 depends on MTRR_SANITIZER 1792 help 1793 mtrr cleanup spare entries default, it can be changed via 1794 mtrr_spare_reg_nr=N on the kernel command line. 1795 1796config X86_PAT 1797 def_bool y 1798 prompt "x86 PAT support" if EXPERT 1799 depends on MTRR 1800 help 1801 Use PAT attributes to setup page level cache control. 1802 1803 PATs are the modern equivalents of MTRRs and are much more 1804 flexible than MTRRs. 1805 1806 Say N here if you see bootup problems (boot crash, boot hang, 1807 spontaneous reboots) or a non-working video driver. 1808 1809 If unsure, say Y. 1810 1811config ARCH_USES_PG_UNCACHED 1812 def_bool y 1813 depends on X86_PAT 1814 1815config X86_UMIP 1816 def_bool y 1817 prompt "User Mode Instruction Prevention" if EXPERT 1818 help 1819 User Mode Instruction Prevention (UMIP) is a security feature in 1820 some x86 processors. If enabled, a general protection fault is 1821 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1822 executed in user mode. These instructions unnecessarily expose 1823 information about the hardware state. 1824 1825 The vast majority of applications do not use these instructions. 1826 For the very few that do, software emulation is provided in 1827 specific cases in protected and virtual-8086 modes. Emulated 1828 results are dummy. 1829 1830config CC_HAS_IBT 1831 # GCC >= 9 and binutils >= 2.29 1832 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1833 # Clang/LLVM >= 14 1834 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1835 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1836 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1837 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1838 $(as-instr,endbr64) 1839 1840config X86_CET 1841 def_bool n 1842 help 1843 CET features configured (Shadow stack or IBT) 1844 1845config X86_KERNEL_IBT 1846 prompt "Indirect Branch Tracking" 1847 def_bool y 1848 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1849 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1850 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1851 select OBJTOOL 1852 select X86_CET 1853 help 1854 Build the kernel with support for Indirect Branch Tracking, a 1855 hardware support course-grain forward-edge Control Flow Integrity 1856 protection. It enforces that all indirect calls must land on 1857 an ENDBR instruction, as such, the compiler will instrument the 1858 code with them to make this happen. 1859 1860 In addition to building the kernel with IBT, seal all functions that 1861 are not indirect call targets, avoiding them ever becoming one. 1862 1863 This requires LTO like objtool runs and will slow down the build. It 1864 does significantly reduce the number of ENDBR instructions in the 1865 kernel image. 1866 1867config X86_INTEL_MEMORY_PROTECTION_KEYS 1868 prompt "Memory Protection Keys" 1869 def_bool y 1870 # Note: only available in 64-bit mode 1871 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1872 select ARCH_USES_HIGH_VMA_FLAGS 1873 select ARCH_HAS_PKEYS 1874 help 1875 Memory Protection Keys provides a mechanism for enforcing 1876 page-based protections, but without requiring modification of the 1877 page tables when an application changes protection domains. 1878 1879 For details, see Documentation/core-api/protection-keys.rst 1880 1881 If unsure, say y. 1882 1883choice 1884 prompt "TSX enable mode" 1885 depends on CPU_SUP_INTEL 1886 default X86_INTEL_TSX_MODE_OFF 1887 help 1888 Intel's TSX (Transactional Synchronization Extensions) feature 1889 allows to optimize locking protocols through lock elision which 1890 can lead to a noticeable performance boost. 1891 1892 On the other hand it has been shown that TSX can be exploited 1893 to form side channel attacks (e.g. TAA) and chances are there 1894 will be more of those attacks discovered in the future. 1895 1896 Therefore TSX is not enabled by default (aka tsx=off). An admin 1897 might override this decision by tsx=on the command line parameter. 1898 Even with TSX enabled, the kernel will attempt to enable the best 1899 possible TAA mitigation setting depending on the microcode available 1900 for the particular machine. 1901 1902 This option allows to set the default tsx mode between tsx=on, =off 1903 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1904 details. 1905 1906 Say off if not sure, auto if TSX is in use but it should be used on safe 1907 platforms or on if TSX is in use and the security aspect of tsx is not 1908 relevant. 1909 1910config X86_INTEL_TSX_MODE_OFF 1911 bool "off" 1912 help 1913 TSX is disabled if possible - equals to tsx=off command line parameter. 1914 1915config X86_INTEL_TSX_MODE_ON 1916 bool "on" 1917 help 1918 TSX is always enabled on TSX capable HW - equals the tsx=on command 1919 line parameter. 1920 1921config X86_INTEL_TSX_MODE_AUTO 1922 bool "auto" 1923 help 1924 TSX is enabled on TSX capable HW that is believed to be safe against 1925 side channel attacks- equals the tsx=auto command line parameter. 1926endchoice 1927 1928config X86_SGX 1929 bool "Software Guard eXtensions (SGX)" 1930 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1931 depends on CRYPTO=y 1932 depends on CRYPTO_SHA256=y 1933 select MMU_NOTIFIER 1934 select NUMA_KEEP_MEMINFO if NUMA 1935 select XARRAY_MULTI 1936 help 1937 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1938 that can be used by applications to set aside private regions of code 1939 and data, referred to as enclaves. An enclave's private memory can 1940 only be accessed by code running within the enclave. Accesses from 1941 outside the enclave, including other enclaves, are disallowed by 1942 hardware. 1943 1944 If unsure, say N. 1945 1946config X86_USER_SHADOW_STACK 1947 bool "X86 userspace shadow stack" 1948 depends on AS_WRUSS 1949 depends on X86_64 1950 select ARCH_USES_HIGH_VMA_FLAGS 1951 select X86_CET 1952 help 1953 Shadow stack protection is a hardware feature that detects function 1954 return address corruption. This helps mitigate ROP attacks. 1955 Applications must be enabled to use it, and old userspace does not 1956 get protection "for free". 1957 1958 CPUs supporting shadow stacks were first released in 2020. 1959 1960 See Documentation/arch/x86/shstk.rst for more information. 1961 1962 If unsure, say N. 1963 1964config INTEL_TDX_HOST 1965 bool "Intel Trust Domain Extensions (TDX) host support" 1966 depends on CPU_SUP_INTEL 1967 depends on X86_64 1968 depends on KVM_INTEL 1969 depends on X86_X2APIC 1970 select ARCH_KEEP_MEMBLOCK 1971 depends on CONTIG_ALLOC 1972 depends on !KEXEC_CORE 1973 depends on X86_MCE 1974 help 1975 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1976 host and certain physical attacks. This option enables necessary TDX 1977 support in the host kernel to run confidential VMs. 1978 1979 If unsure, say N. 1980 1981config EFI 1982 bool "EFI runtime service support" 1983 depends on ACPI 1984 select UCS2_STRING 1985 select EFI_RUNTIME_WRAPPERS 1986 select ARCH_USE_MEMREMAP_PROT 1987 select EFI_RUNTIME_MAP if KEXEC_CORE 1988 help 1989 This enables the kernel to use EFI runtime services that are 1990 available (such as the EFI variable services). 1991 1992 This option is only useful on systems that have EFI firmware. 1993 In addition, you should use the latest ELILO loader available 1994 at <http://elilo.sourceforge.net> in order to take advantage 1995 of EFI runtime services. However, even with this option, the 1996 resultant kernel should continue to boot on existing non-EFI 1997 platforms. 1998 1999config EFI_STUB 2000 bool "EFI stub support" 2001 depends on EFI 2002 select RELOCATABLE 2003 help 2004 This kernel feature allows a bzImage to be loaded directly 2005 by EFI firmware without the use of a bootloader. 2006 2007 See Documentation/admin-guide/efi-stub.rst for more information. 2008 2009config EFI_HANDOVER_PROTOCOL 2010 bool "EFI handover protocol (DEPRECATED)" 2011 depends on EFI_STUB 2012 default y 2013 help 2014 Select this in order to include support for the deprecated EFI 2015 handover protocol, which defines alternative entry points into the 2016 EFI stub. This is a practice that has no basis in the UEFI 2017 specification, and requires a priori knowledge on the part of the 2018 bootloader about Linux/x86 specific ways of passing the command line 2019 and initrd, and where in memory those assets may be loaded. 2020 2021 If in doubt, say Y. Even though the corresponding support is not 2022 present in upstream GRUB or other bootloaders, most distros build 2023 GRUB with numerous downstream patches applied, and may rely on the 2024 handover protocol as as result. 2025 2026config EFI_MIXED 2027 bool "EFI mixed-mode support" 2028 depends on EFI_STUB && X86_64 2029 help 2030 Enabling this feature allows a 64-bit kernel to be booted 2031 on a 32-bit firmware, provided that your CPU supports 64-bit 2032 mode. 2033 2034 Note that it is not possible to boot a mixed-mode enabled 2035 kernel via the EFI boot stub - a bootloader that supports 2036 the EFI handover protocol must be used. 2037 2038 If unsure, say N. 2039 2040config EFI_FAKE_MEMMAP 2041 bool "Enable EFI fake memory map" 2042 depends on EFI 2043 help 2044 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2045 this parameter, you can add arbitrary attribute to specific memory 2046 range by updating original (firmware provided) EFI memmap. This is 2047 useful for debugging of EFI memmap related feature, e.g., Address 2048 Range Mirroring feature. 2049 2050config EFI_MAX_FAKE_MEM 2051 int "maximum allowable number of ranges in efi_fake_mem boot option" 2052 depends on EFI_FAKE_MEMMAP 2053 range 1 128 2054 default 8 2055 help 2056 Maximum allowable number of ranges in efi_fake_mem boot option. 2057 Ranges can be set up to this value using comma-separated list. 2058 The default value is 8. 2059 2060config EFI_RUNTIME_MAP 2061 bool "Export EFI runtime maps to sysfs" if EXPERT 2062 depends on EFI 2063 help 2064 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2065 That memory map is required by the 2nd kernel to set up EFI virtual 2066 mappings after kexec, but can also be used for debugging purposes. 2067 2068 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2069 2070source "kernel/Kconfig.hz" 2071 2072config ARCH_SUPPORTS_KEXEC 2073 def_bool y 2074 2075config ARCH_SUPPORTS_KEXEC_FILE 2076 def_bool X86_64 2077 2078config ARCH_SELECTS_KEXEC_FILE 2079 def_bool y 2080 depends on KEXEC_FILE 2081 select HAVE_IMA_KEXEC if IMA 2082 2083config ARCH_SUPPORTS_KEXEC_PURGATORY 2084 def_bool y 2085 2086config ARCH_SUPPORTS_KEXEC_SIG 2087 def_bool y 2088 2089config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2090 def_bool y 2091 2092config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2093 def_bool y 2094 2095config ARCH_SUPPORTS_KEXEC_JUMP 2096 def_bool y 2097 2098config ARCH_SUPPORTS_CRASH_DUMP 2099 def_bool X86_64 || (X86_32 && HIGHMEM) 2100 2101config ARCH_SUPPORTS_CRASH_HOTPLUG 2102 def_bool y 2103 2104config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2105 def_bool CRASH_RESERVE 2106 2107config PHYSICAL_START 2108 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2109 default "0x1000000" 2110 help 2111 This gives the physical address where the kernel is loaded. 2112 2113 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage 2114 will decompress itself to above physical address and run from there. 2115 Otherwise, bzImage will run from the address where it has been loaded 2116 by the boot loader. The only exception is if it is loaded below the 2117 above physical address, in which case it will relocate itself there. 2118 2119 In normal kdump cases one does not have to set/change this option 2120 as now bzImage can be compiled as a completely relocatable image 2121 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2122 address. This option is mainly useful for the folks who don't want 2123 to use a bzImage for capturing the crash dump and want to use a 2124 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2125 to be specifically compiled to run from a specific memory area 2126 (normally a reserved region) and this option comes handy. 2127 2128 So if you are using bzImage for capturing the crash dump, 2129 leave the value here unchanged to 0x1000000 and set 2130 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2131 for capturing the crash dump change this value to start of 2132 the reserved region. In other words, it can be set based on 2133 the "X" value as specified in the "crashkernel=YM@XM" 2134 command line boot parameter passed to the panic-ed 2135 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2136 for more details about crash dumps. 2137 2138 Usage of bzImage for capturing the crash dump is recommended as 2139 one does not have to build two kernels. Same kernel can be used 2140 as production kernel and capture kernel. Above option should have 2141 gone away after relocatable bzImage support is introduced. But it 2142 is present because there are users out there who continue to use 2143 vmlinux for dump capture. This option should go away down the 2144 line. 2145 2146 Don't change this unless you know what you are doing. 2147 2148config RELOCATABLE 2149 bool "Build a relocatable kernel" 2150 default y 2151 help 2152 This builds a kernel image that retains relocation information 2153 so it can be loaded someplace besides the default 1MB. 2154 The relocations tend to make the kernel binary about 10% larger, 2155 but are discarded at runtime. 2156 2157 One use is for the kexec on panic case where the recovery kernel 2158 must live at a different physical address than the primary 2159 kernel. 2160 2161 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2162 it has been loaded at and the compile time physical address 2163 (CONFIG_PHYSICAL_START) is used as the minimum location. 2164 2165config RANDOMIZE_BASE 2166 bool "Randomize the address of the kernel image (KASLR)" 2167 depends on RELOCATABLE 2168 default y 2169 help 2170 In support of Kernel Address Space Layout Randomization (KASLR), 2171 this randomizes the physical address at which the kernel image 2172 is decompressed and the virtual address where the kernel 2173 image is mapped, as a security feature that deters exploit 2174 attempts relying on knowledge of the location of kernel 2175 code internals. 2176 2177 On 64-bit, the kernel physical and virtual addresses are 2178 randomized separately. The physical address will be anywhere 2179 between 16MB and the top of physical memory (up to 64TB). The 2180 virtual address will be randomized from 16MB up to 1GB (9 bits 2181 of entropy). Note that this also reduces the memory space 2182 available to kernel modules from 1.5GB to 1GB. 2183 2184 On 32-bit, the kernel physical and virtual addresses are 2185 randomized together. They will be randomized from 16MB up to 2186 512MB (8 bits of entropy). 2187 2188 Entropy is generated using the RDRAND instruction if it is 2189 supported. If RDTSC is supported, its value is mixed into 2190 the entropy pool as well. If neither RDRAND nor RDTSC are 2191 supported, then entropy is read from the i8254 timer. The 2192 usable entropy is limited by the kernel being built using 2193 2GB addressing, and that PHYSICAL_ALIGN must be at a 2194 minimum of 2MB. As a result, only 10 bits of entropy are 2195 theoretically possible, but the implementations are further 2196 limited due to memory layouts. 2197 2198 If unsure, say Y. 2199 2200# Relocation on x86 needs some additional build support 2201config X86_NEED_RELOCS 2202 def_bool y 2203 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2204 2205config PHYSICAL_ALIGN 2206 hex "Alignment value to which kernel should be aligned" 2207 default "0x200000" 2208 range 0x2000 0x1000000 if X86_32 2209 range 0x200000 0x1000000 if X86_64 2210 help 2211 This value puts the alignment restrictions on physical address 2212 where kernel is loaded and run from. Kernel is compiled for an 2213 address which meets above alignment restriction. 2214 2215 If bootloader loads the kernel at a non-aligned address and 2216 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2217 address aligned to above value and run from there. 2218 2219 If bootloader loads the kernel at a non-aligned address and 2220 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2221 load address and decompress itself to the address it has been 2222 compiled for and run from there. The address for which kernel is 2223 compiled already meets above alignment restrictions. Hence the 2224 end result is that kernel runs from a physical address meeting 2225 above alignment restrictions. 2226 2227 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2228 this value must be a multiple of 0x200000. 2229 2230 Don't change this unless you know what you are doing. 2231 2232config DYNAMIC_MEMORY_LAYOUT 2233 bool 2234 help 2235 This option makes base addresses of vmalloc and vmemmap as well as 2236 __PAGE_OFFSET movable during boot. 2237 2238config RANDOMIZE_MEMORY 2239 bool "Randomize the kernel memory sections" 2240 depends on X86_64 2241 depends on RANDOMIZE_BASE 2242 select DYNAMIC_MEMORY_LAYOUT 2243 default RANDOMIZE_BASE 2244 help 2245 Randomizes the base virtual address of kernel memory sections 2246 (physical memory mapping, vmalloc & vmemmap). This security feature 2247 makes exploits relying on predictable memory locations less reliable. 2248 2249 The order of allocations remains unchanged. Entropy is generated in 2250 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2251 configuration have in average 30,000 different possible virtual 2252 addresses for each memory section. 2253 2254 If unsure, say Y. 2255 2256config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2257 hex "Physical memory mapping padding" if EXPERT 2258 depends on RANDOMIZE_MEMORY 2259 default "0xa" if MEMORY_HOTPLUG 2260 default "0x0" 2261 range 0x1 0x40 if MEMORY_HOTPLUG 2262 range 0x0 0x40 2263 help 2264 Define the padding in terabytes added to the existing physical 2265 memory size during kernel memory randomization. It is useful 2266 for memory hotplug support but reduces the entropy available for 2267 address randomization. 2268 2269 If unsure, leave at the default value. 2270 2271config ADDRESS_MASKING 2272 bool "Linear Address Masking support" 2273 depends on X86_64 2274 help 2275 Linear Address Masking (LAM) modifies the checking that is applied 2276 to 64-bit linear addresses, allowing software to use of the 2277 untranslated address bits for metadata. 2278 2279 The capability can be used for efficient address sanitizers (ASAN) 2280 implementation and for optimizations in JITs. 2281 2282config HOTPLUG_CPU 2283 def_bool y 2284 depends on SMP 2285 2286config COMPAT_VDSO 2287 def_bool n 2288 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2289 depends on COMPAT_32 2290 help 2291 Certain buggy versions of glibc will crash if they are 2292 presented with a 32-bit vDSO that is not mapped at the address 2293 indicated in its segment table. 2294 2295 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2296 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2297 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2298 the only released version with the bug, but OpenSUSE 9 2299 contains a buggy "glibc 2.3.2". 2300 2301 The symptom of the bug is that everything crashes on startup, saying: 2302 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2303 2304 Saying Y here changes the default value of the vdso32 boot 2305 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2306 This works around the glibc bug but hurts performance. 2307 2308 If unsure, say N: if you are compiling your own kernel, you 2309 are unlikely to be using a buggy version of glibc. 2310 2311choice 2312 prompt "vsyscall table for legacy applications" 2313 depends on X86_64 2314 default LEGACY_VSYSCALL_XONLY 2315 help 2316 Legacy user code that does not know how to find the vDSO expects 2317 to be able to issue three syscalls by calling fixed addresses in 2318 kernel space. Since this location is not randomized with ASLR, 2319 it can be used to assist security vulnerability exploitation. 2320 2321 This setting can be changed at boot time via the kernel command 2322 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2323 is deprecated and can only be enabled using the kernel command 2324 line. 2325 2326 On a system with recent enough glibc (2.14 or newer) and no 2327 static binaries, you can say None without a performance penalty 2328 to improve security. 2329 2330 If unsure, select "Emulate execution only". 2331 2332 config LEGACY_VSYSCALL_XONLY 2333 bool "Emulate execution only" 2334 help 2335 The kernel traps and emulates calls into the fixed vsyscall 2336 address mapping and does not allow reads. This 2337 configuration is recommended when userspace might use the 2338 legacy vsyscall area but support for legacy binary 2339 instrumentation of legacy code is not needed. It mitigates 2340 certain uses of the vsyscall area as an ASLR-bypassing 2341 buffer. 2342 2343 config LEGACY_VSYSCALL_NONE 2344 bool "None" 2345 help 2346 There will be no vsyscall mapping at all. This will 2347 eliminate any risk of ASLR bypass due to the vsyscall 2348 fixed address mapping. Attempts to use the vsyscalls 2349 will be reported to dmesg, so that either old or 2350 malicious userspace programs can be identified. 2351 2352endchoice 2353 2354config CMDLINE_BOOL 2355 bool "Built-in kernel command line" 2356 help 2357 Allow for specifying boot arguments to the kernel at 2358 build time. On some systems (e.g. embedded ones), it is 2359 necessary or convenient to provide some or all of the 2360 kernel boot arguments with the kernel itself (that is, 2361 to not rely on the boot loader to provide them.) 2362 2363 To compile command line arguments into the kernel, 2364 set this option to 'Y', then fill in the 2365 boot arguments in CONFIG_CMDLINE. 2366 2367 Systems with fully functional boot loaders (i.e. non-embedded) 2368 should leave this option set to 'N'. 2369 2370config CMDLINE 2371 string "Built-in kernel command string" 2372 depends on CMDLINE_BOOL 2373 default "" 2374 help 2375 Enter arguments here that should be compiled into the kernel 2376 image and used at boot time. If the boot loader provides a 2377 command line at boot time, it is appended to this string to 2378 form the full kernel command line, when the system boots. 2379 2380 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2381 change this behavior. 2382 2383 In most cases, the command line (whether built-in or provided 2384 by the boot loader) should specify the device for the root 2385 file system. 2386 2387config CMDLINE_OVERRIDE 2388 bool "Built-in command line overrides boot loader arguments" 2389 depends on CMDLINE_BOOL && CMDLINE != "" 2390 help 2391 Set this option to 'Y' to have the kernel ignore the boot loader 2392 command line, and use ONLY the built-in command line. 2393 2394 This is used to work around broken boot loaders. This should 2395 be set to 'N' under normal conditions. 2396 2397config MODIFY_LDT_SYSCALL 2398 bool "Enable the LDT (local descriptor table)" if EXPERT 2399 default y 2400 help 2401 Linux can allow user programs to install a per-process x86 2402 Local Descriptor Table (LDT) using the modify_ldt(2) system 2403 call. This is required to run 16-bit or segmented code such as 2404 DOSEMU or some Wine programs. It is also used by some very old 2405 threading libraries. 2406 2407 Enabling this feature adds a small amount of overhead to 2408 context switches and increases the low-level kernel attack 2409 surface. Disabling it removes the modify_ldt(2) system call. 2410 2411 Saying 'N' here may make sense for embedded or server kernels. 2412 2413config STRICT_SIGALTSTACK_SIZE 2414 bool "Enforce strict size checking for sigaltstack" 2415 depends on DYNAMIC_SIGFRAME 2416 help 2417 For historical reasons MINSIGSTKSZ is a constant which became 2418 already too small with AVX512 support. Add a mechanism to 2419 enforce strict checking of the sigaltstack size against the 2420 real size of the FPU frame. This option enables the check 2421 by default. It can also be controlled via the kernel command 2422 line option 'strict_sas_size' independent of this config 2423 switch. Enabling it might break existing applications which 2424 allocate a too small sigaltstack but 'work' because they 2425 never get a signal delivered. 2426 2427 Say 'N' unless you want to really enforce this check. 2428 2429source "kernel/livepatch/Kconfig" 2430 2431endmenu 2432 2433config CC_HAS_NAMED_AS 2434 def_bool CC_IS_GCC && GCC_VERSION >= 90100 2435 2436config CC_HAS_NAMED_AS_FIXED_SANITIZERS 2437 def_bool CC_IS_GCC && GCC_VERSION >= 130300 2438 2439config USE_X86_SEG_SUPPORT 2440 def_bool y 2441 depends on CC_HAS_NAMED_AS 2442 # 2443 # -fsanitize=kernel-address (KASAN) and -fsanitize=thread 2444 # (KCSAN) are incompatible with named address spaces with 2445 # GCC < 13.3 - see GCC PR sanitizer/111736. 2446 # 2447 depends on !(KASAN || KCSAN) || CC_HAS_NAMED_AS_FIXED_SANITIZERS 2448 2449config CC_HAS_SLS 2450 def_bool $(cc-option,-mharden-sls=all) 2451 2452config CC_HAS_RETURN_THUNK 2453 def_bool $(cc-option,-mfunction-return=thunk-extern) 2454 2455config CC_HAS_ENTRY_PADDING 2456 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2457 2458config FUNCTION_PADDING_CFI 2459 int 2460 default 59 if FUNCTION_ALIGNMENT_64B 2461 default 27 if FUNCTION_ALIGNMENT_32B 2462 default 11 if FUNCTION_ALIGNMENT_16B 2463 default 3 if FUNCTION_ALIGNMENT_8B 2464 default 0 2465 2466# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2467# except Kconfig can't do arithmetic :/ 2468config FUNCTION_PADDING_BYTES 2469 int 2470 default FUNCTION_PADDING_CFI if CFI_CLANG 2471 default FUNCTION_ALIGNMENT 2472 2473config CALL_PADDING 2474 def_bool n 2475 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2476 select FUNCTION_ALIGNMENT_16B 2477 2478config FINEIBT 2479 def_bool y 2480 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE 2481 select CALL_PADDING 2482 2483config HAVE_CALL_THUNKS 2484 def_bool y 2485 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL 2486 2487config CALL_THUNKS 2488 def_bool n 2489 select CALL_PADDING 2490 2491config PREFIX_SYMBOLS 2492 def_bool y 2493 depends on CALL_PADDING && !CFI_CLANG 2494 2495menuconfig CPU_MITIGATIONS 2496 bool "Mitigations for CPU vulnerabilities" 2497 default y 2498 help 2499 Say Y here to enable options which enable mitigations for hardware 2500 vulnerabilities (usually related to speculative execution). 2501 Mitigations can be disabled or restricted to SMT systems at runtime 2502 via the "mitigations" kernel parameter. 2503 2504 If you say N, all mitigations will be disabled. This CANNOT be 2505 overridden at runtime. 2506 2507 Say 'Y', unless you really know what you are doing. 2508 2509if CPU_MITIGATIONS 2510 2511config MITIGATION_PAGE_TABLE_ISOLATION 2512 bool "Remove the kernel mapping in user mode" 2513 default y 2514 depends on (X86_64 || X86_PAE) 2515 help 2516 This feature reduces the number of hardware side channels by 2517 ensuring that the majority of kernel addresses are not mapped 2518 into userspace. 2519 2520 See Documentation/arch/x86/pti.rst for more details. 2521 2522config MITIGATION_RETPOLINE 2523 bool "Avoid speculative indirect branches in kernel" 2524 select OBJTOOL if HAVE_OBJTOOL 2525 default y 2526 help 2527 Compile kernel with the retpoline compiler options to guard against 2528 kernel-to-user data leaks by avoiding speculative indirect 2529 branches. Requires a compiler with -mindirect-branch=thunk-extern 2530 support for full protection. The kernel may run slower. 2531 2532config MITIGATION_RETHUNK 2533 bool "Enable return-thunks" 2534 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK 2535 select OBJTOOL if HAVE_OBJTOOL 2536 default y if X86_64 2537 help 2538 Compile the kernel with the return-thunks compiler option to guard 2539 against kernel-to-user data leaks by avoiding return speculation. 2540 Requires a compiler with -mfunction-return=thunk-extern 2541 support for full protection. The kernel may run slower. 2542 2543config MITIGATION_UNRET_ENTRY 2544 bool "Enable UNRET on kernel entry" 2545 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64 2546 default y 2547 help 2548 Compile the kernel with support for the retbleed=unret mitigation. 2549 2550config MITIGATION_CALL_DEPTH_TRACKING 2551 bool "Mitigate RSB underflow with call depth tracking" 2552 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2553 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2554 select CALL_THUNKS 2555 default y 2556 help 2557 Compile the kernel with call depth tracking to mitigate the Intel 2558 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2559 mitigation is off by default and needs to be enabled on the 2560 kernel command line via the retbleed=stuff option. For 2561 non-affected systems the overhead of this option is marginal as 2562 the call depth tracking is using run-time generated call thunks 2563 in a compiler generated padding area and call patching. This 2564 increases text size by ~5%. For non affected systems this space 2565 is unused. On affected SKL systems this results in a significant 2566 performance gain over the IBRS mitigation. 2567 2568config CALL_THUNKS_DEBUG 2569 bool "Enable call thunks and call depth tracking debugging" 2570 depends on MITIGATION_CALL_DEPTH_TRACKING 2571 select FUNCTION_ALIGNMENT_32B 2572 default n 2573 help 2574 Enable call/ret counters for imbalance detection and build in 2575 a noisy dmesg about callthunks generation and call patching for 2576 trouble shooting. The debug prints need to be enabled on the 2577 kernel command line with 'debug-callthunks'. 2578 Only enable this when you are debugging call thunks as this 2579 creates a noticeable runtime overhead. If unsure say N. 2580 2581config MITIGATION_IBPB_ENTRY 2582 bool "Enable IBPB on kernel entry" 2583 depends on CPU_SUP_AMD && X86_64 2584 default y 2585 help 2586 Compile the kernel with support for the retbleed=ibpb mitigation. 2587 2588config MITIGATION_IBRS_ENTRY 2589 bool "Enable IBRS on kernel entry" 2590 depends on CPU_SUP_INTEL && X86_64 2591 default y 2592 help 2593 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2594 This mitigates both spectre_v2 and retbleed at great cost to 2595 performance. 2596 2597config MITIGATION_SRSO 2598 bool "Mitigate speculative RAS overflow on AMD" 2599 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK 2600 default y 2601 help 2602 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2603 2604config MITIGATION_SLS 2605 bool "Mitigate Straight-Line-Speculation" 2606 depends on CC_HAS_SLS && X86_64 2607 select OBJTOOL if HAVE_OBJTOOL 2608 default n 2609 help 2610 Compile the kernel with straight-line-speculation options to guard 2611 against straight line speculation. The kernel image might be slightly 2612 larger. 2613 2614config MITIGATION_GDS_FORCE 2615 bool "Force GDS Mitigation" 2616 depends on CPU_SUP_INTEL 2617 default n 2618 help 2619 Gather Data Sampling (GDS) is a hardware vulnerability which allows 2620 unprivileged speculative access to data which was previously stored in 2621 vector registers. 2622 2623 This option is equivalent to setting gather_data_sampling=force on the 2624 command line. The microcode mitigation is used if present, otherwise 2625 AVX is disabled as a mitigation. On affected systems that are missing 2626 the microcode any userspace code that unconditionally uses AVX will 2627 break with this option set. 2628 2629 Setting this option on systems not vulnerable to GDS has no effect. 2630 2631 If in doubt, say N. 2632 2633config MITIGATION_RFDS 2634 bool "RFDS Mitigation" 2635 depends on CPU_SUP_INTEL 2636 default y 2637 help 2638 Enable mitigation for Register File Data Sampling (RFDS) by default. 2639 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It 2640 allows unprivileged speculative access to stale data previously 2641 stored in floating point, vector and integer registers. 2642 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> 2643 2644config MITIGATION_SPECTRE_BHI 2645 bool "Mitigate Spectre-BHB (Branch History Injection)" 2646 depends on CPU_SUP_INTEL 2647 default y 2648 help 2649 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks 2650 where the branch history buffer is poisoned to speculatively steer 2651 indirect branches. 2652 See <file:Documentation/admin-guide/hw-vuln/spectre.rst> 2653 2654endif 2655 2656config ARCH_HAS_ADD_PAGES 2657 def_bool y 2658 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2659 2660menu "Power management and ACPI options" 2661 2662config ARCH_HIBERNATION_HEADER 2663 def_bool y 2664 depends on HIBERNATION 2665 2666source "kernel/power/Kconfig" 2667 2668source "drivers/acpi/Kconfig" 2669 2670config X86_APM_BOOT 2671 def_bool y 2672 depends on APM 2673 2674menuconfig APM 2675 tristate "APM (Advanced Power Management) BIOS support" 2676 depends on X86_32 && PM_SLEEP 2677 help 2678 APM is a BIOS specification for saving power using several different 2679 techniques. This is mostly useful for battery powered laptops with 2680 APM compliant BIOSes. If you say Y here, the system time will be 2681 reset after a RESUME operation, the /proc/apm device will provide 2682 battery status information, and user-space programs will receive 2683 notification of APM "events" (e.g. battery status change). 2684 2685 If you select "Y" here, you can disable actual use of the APM 2686 BIOS by passing the "apm=off" option to the kernel at boot time. 2687 2688 Note that the APM support is almost completely disabled for 2689 machines with more than one CPU. 2690 2691 In order to use APM, you will need supporting software. For location 2692 and more information, read <file:Documentation/power/apm-acpi.rst> 2693 and the Battery Powered Linux mini-HOWTO, available from 2694 <http://www.tldp.org/docs.html#howto>. 2695 2696 This driver does not spin down disk drives (see the hdparm(8) 2697 manpage ("man 8 hdparm") for that), and it doesn't turn off 2698 VESA-compliant "green" monitors. 2699 2700 This driver does not support the TI 4000M TravelMate and the ACER 2701 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2702 desktop machines also don't have compliant BIOSes, and this driver 2703 may cause those machines to panic during the boot phase. 2704 2705 Generally, if you don't have a battery in your machine, there isn't 2706 much point in using this driver and you should say N. If you get 2707 random kernel OOPSes or reboots that don't seem to be related to 2708 anything, try disabling/enabling this option (or disabling/enabling 2709 APM in your BIOS). 2710 2711 Some other things you should try when experiencing seemingly random, 2712 "weird" problems: 2713 2714 1) make sure that you have enough swap space and that it is 2715 enabled. 2716 2) pass the "idle=poll" option to the kernel 2717 3) switch on floating point emulation in the kernel and pass 2718 the "no387" option to the kernel 2719 4) pass the "floppy=nodma" option to the kernel 2720 5) pass the "mem=4M" option to the kernel (thereby disabling 2721 all but the first 4 MB of RAM) 2722 6) make sure that the CPU is not over clocked. 2723 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2724 8) disable the cache from your BIOS settings 2725 9) install a fan for the video card or exchange video RAM 2726 10) install a better fan for the CPU 2727 11) exchange RAM chips 2728 12) exchange the motherboard. 2729 2730 To compile this driver as a module, choose M here: the 2731 module will be called apm. 2732 2733if APM 2734 2735config APM_IGNORE_USER_SUSPEND 2736 bool "Ignore USER SUSPEND" 2737 help 2738 This option will ignore USER SUSPEND requests. On machines with a 2739 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2740 series notebooks, it is necessary to say Y because of a BIOS bug. 2741 2742config APM_DO_ENABLE 2743 bool "Enable PM at boot time" 2744 help 2745 Enable APM features at boot time. From page 36 of the APM BIOS 2746 specification: "When disabled, the APM BIOS does not automatically 2747 power manage devices, enter the Standby State, enter the Suspend 2748 State, or take power saving steps in response to CPU Idle calls." 2749 This driver will make CPU Idle calls when Linux is idle (unless this 2750 feature is turned off -- see "Do CPU IDLE calls", below). This 2751 should always save battery power, but more complicated APM features 2752 will be dependent on your BIOS implementation. You may need to turn 2753 this option off if your computer hangs at boot time when using APM 2754 support, or if it beeps continuously instead of suspending. Turn 2755 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2756 T400CDT. This is off by default since most machines do fine without 2757 this feature. 2758 2759config APM_CPU_IDLE 2760 depends on CPU_IDLE 2761 bool "Make CPU Idle calls when idle" 2762 help 2763 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2764 On some machines, this can activate improved power savings, such as 2765 a slowed CPU clock rate, when the machine is idle. These idle calls 2766 are made after the idle loop has run for some length of time (e.g., 2767 333 mS). On some machines, this will cause a hang at boot time or 2768 whenever the CPU becomes idle. (On machines with more than one CPU, 2769 this option does nothing.) 2770 2771config APM_DISPLAY_BLANK 2772 bool "Enable console blanking using APM" 2773 help 2774 Enable console blanking using the APM. Some laptops can use this to 2775 turn off the LCD backlight when the screen blanker of the Linux 2776 virtual console blanks the screen. Note that this is only used by 2777 the virtual console screen blanker, and won't turn off the backlight 2778 when using the X Window system. This also doesn't have anything to 2779 do with your VESA-compliant power-saving monitor. Further, this 2780 option doesn't work for all laptops -- it might not turn off your 2781 backlight at all, or it might print a lot of errors to the console, 2782 especially if you are using gpm. 2783 2784config APM_ALLOW_INTS 2785 bool "Allow interrupts during APM BIOS calls" 2786 help 2787 Normally we disable external interrupts while we are making calls to 2788 the APM BIOS as a measure to lessen the effects of a badly behaving 2789 BIOS implementation. The BIOS should reenable interrupts if it 2790 needs to. Unfortunately, some BIOSes do not -- especially those in 2791 many of the newer IBM Thinkpads. If you experience hangs when you 2792 suspend, try setting this to Y. Otherwise, say N. 2793 2794endif # APM 2795 2796source "drivers/cpufreq/Kconfig" 2797 2798source "drivers/cpuidle/Kconfig" 2799 2800source "drivers/idle/Kconfig" 2801 2802endmenu 2803 2804menu "Bus options (PCI etc.)" 2805 2806choice 2807 prompt "PCI access mode" 2808 depends on X86_32 && PCI 2809 default PCI_GOANY 2810 help 2811 On PCI systems, the BIOS can be used to detect the PCI devices and 2812 determine their configuration. However, some old PCI motherboards 2813 have BIOS bugs and may crash if this is done. Also, some embedded 2814 PCI-based systems don't have any BIOS at all. Linux can also try to 2815 detect the PCI hardware directly without using the BIOS. 2816 2817 With this option, you can specify how Linux should detect the 2818 PCI devices. If you choose "BIOS", the BIOS will be used, 2819 if you choose "Direct", the BIOS won't be used, and if you 2820 choose "MMConfig", then PCI Express MMCONFIG will be used. 2821 If you choose "Any", the kernel will try MMCONFIG, then the 2822 direct access method and falls back to the BIOS if that doesn't 2823 work. If unsure, go with the default, which is "Any". 2824 2825config PCI_GOBIOS 2826 bool "BIOS" 2827 2828config PCI_GOMMCONFIG 2829 bool "MMConfig" 2830 2831config PCI_GODIRECT 2832 bool "Direct" 2833 2834config PCI_GOOLPC 2835 bool "OLPC XO-1" 2836 depends on OLPC 2837 2838config PCI_GOANY 2839 bool "Any" 2840 2841endchoice 2842 2843config PCI_BIOS 2844 def_bool y 2845 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2846 2847# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2848config PCI_DIRECT 2849 def_bool y 2850 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2851 2852config PCI_MMCONFIG 2853 bool "Support mmconfig PCI config space access" if X86_64 2854 default y 2855 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2856 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2857 2858config PCI_OLPC 2859 def_bool y 2860 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2861 2862config PCI_XEN 2863 def_bool y 2864 depends on PCI && XEN 2865 2866config MMCONF_FAM10H 2867 def_bool y 2868 depends on X86_64 && PCI_MMCONFIG && ACPI 2869 2870config PCI_CNB20LE_QUIRK 2871 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2872 depends on PCI 2873 help 2874 Read the PCI windows out of the CNB20LE host bridge. This allows 2875 PCI hotplug to work on systems with the CNB20LE chipset which do 2876 not have ACPI. 2877 2878 There's no public spec for this chipset, and this functionality 2879 is known to be incomplete. 2880 2881 You should say N unless you know you need this. 2882 2883config ISA_BUS 2884 bool "ISA bus support on modern systems" if EXPERT 2885 help 2886 Expose ISA bus device drivers and options available for selection and 2887 configuration. Enable this option if your target machine has an ISA 2888 bus. ISA is an older system, displaced by PCI and newer bus 2889 architectures -- if your target machine is modern, it probably does 2890 not have an ISA bus. 2891 2892 If unsure, say N. 2893 2894# x86_64 have no ISA slots, but can have ISA-style DMA. 2895config ISA_DMA_API 2896 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2897 default y 2898 help 2899 Enables ISA-style DMA support for devices requiring such controllers. 2900 If unsure, say Y. 2901 2902if X86_32 2903 2904config ISA 2905 bool "ISA support" 2906 help 2907 Find out whether you have ISA slots on your motherboard. ISA is the 2908 name of a bus system, i.e. the way the CPU talks to the other stuff 2909 inside your box. Other bus systems are PCI, EISA, MicroChannel 2910 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2911 newer boards don't support it. If you have ISA, say Y, otherwise N. 2912 2913config SCx200 2914 tristate "NatSemi SCx200 support" 2915 help 2916 This provides basic support for National Semiconductor's 2917 (now AMD's) Geode processors. The driver probes for the 2918 PCI-IDs of several on-chip devices, so its a good dependency 2919 for other scx200_* drivers. 2920 2921 If compiled as a module, the driver is named scx200. 2922 2923config SCx200HR_TIMER 2924 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2925 depends on SCx200 2926 default y 2927 help 2928 This driver provides a clocksource built upon the on-chip 2929 27MHz high-resolution timer. Its also a workaround for 2930 NSC Geode SC-1100's buggy TSC, which loses time when the 2931 processor goes idle (as is done by the scheduler). The 2932 other workaround is idle=poll boot option. 2933 2934config OLPC 2935 bool "One Laptop Per Child support" 2936 depends on !X86_PAE 2937 select GPIOLIB 2938 select OF 2939 select OF_PROMTREE 2940 select IRQ_DOMAIN 2941 select OLPC_EC 2942 help 2943 Add support for detecting the unique features of the OLPC 2944 XO hardware. 2945 2946config OLPC_XO1_PM 2947 bool "OLPC XO-1 Power Management" 2948 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2949 help 2950 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2951 2952config OLPC_XO1_RTC 2953 bool "OLPC XO-1 Real Time Clock" 2954 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2955 help 2956 Add support for the XO-1 real time clock, which can be used as a 2957 programmable wakeup source. 2958 2959config OLPC_XO1_SCI 2960 bool "OLPC XO-1 SCI extras" 2961 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2962 depends on INPUT=y 2963 select POWER_SUPPLY 2964 help 2965 Add support for SCI-based features of the OLPC XO-1 laptop: 2966 - EC-driven system wakeups 2967 - Power button 2968 - Ebook switch 2969 - Lid switch 2970 - AC adapter status updates 2971 - Battery status updates 2972 2973config OLPC_XO15_SCI 2974 bool "OLPC XO-1.5 SCI extras" 2975 depends on OLPC && ACPI 2976 select POWER_SUPPLY 2977 help 2978 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2979 - EC-driven system wakeups 2980 - AC adapter status updates 2981 - Battery status updates 2982 2983config ALIX 2984 bool "PCEngines ALIX System Support (LED setup)" 2985 select GPIOLIB 2986 help 2987 This option enables system support for the PCEngines ALIX. 2988 At present this just sets up LEDs for GPIO control on 2989 ALIX2/3/6 boards. However, other system specific setup should 2990 get added here. 2991 2992 Note: You must still enable the drivers for GPIO and LED support 2993 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2994 2995 Note: You have to set alix.force=1 for boards with Award BIOS. 2996 2997config NET5501 2998 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2999 select GPIOLIB 3000 help 3001 This option enables system support for the Soekris Engineering net5501. 3002 3003config GEOS 3004 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 3005 select GPIOLIB 3006 depends on DMI 3007 help 3008 This option enables system support for the Traverse Technologies GEOS. 3009 3010config TS5500 3011 bool "Technologic Systems TS-5500 platform support" 3012 depends on MELAN 3013 select CHECK_SIGNATURE 3014 select NEW_LEDS 3015 select LEDS_CLASS 3016 help 3017 This option enables system support for the Technologic Systems TS-5500. 3018 3019endif # X86_32 3020 3021config AMD_NB 3022 def_bool y 3023 depends on CPU_SUP_AMD && PCI 3024 3025endmenu 3026 3027menu "Binary Emulations" 3028 3029config IA32_EMULATION 3030 bool "IA32 Emulation" 3031 depends on X86_64 3032 select ARCH_WANT_OLD_COMPAT_IPC 3033 select BINFMT_ELF 3034 select COMPAT_OLD_SIGACTION 3035 help 3036 Include code to run legacy 32-bit programs under a 3037 64-bit kernel. You should likely turn this on, unless you're 3038 100% sure that you don't have any 32-bit programs left. 3039 3040config IA32_EMULATION_DEFAULT_DISABLED 3041 bool "IA32 emulation disabled by default" 3042 default n 3043 depends on IA32_EMULATION 3044 help 3045 Make IA32 emulation disabled by default. This prevents loading 32-bit 3046 processes and access to 32-bit syscalls. If unsure, leave it to its 3047 default value. 3048 3049config X86_X32_ABI 3050 bool "x32 ABI for 64-bit mode" 3051 depends on X86_64 3052 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3053 # compressed debug sections to x86_x32 properly: 3054 # https://github.com/ClangBuiltLinux/linux/issues/514 3055 # https://github.com/ClangBuiltLinux/linux/issues/1141 3056 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3057 help 3058 Include code to run binaries for the x32 native 32-bit ABI 3059 for 64-bit processors. An x32 process gets access to the 3060 full 64-bit register file and wide data path while leaving 3061 pointers at 32 bits for smaller memory footprint. 3062 3063config COMPAT_32 3064 def_bool y 3065 depends on IA32_EMULATION || X86_32 3066 select HAVE_UID16 3067 select OLD_SIGSUSPEND3 3068 3069config COMPAT 3070 def_bool y 3071 depends on IA32_EMULATION || X86_X32_ABI 3072 3073config COMPAT_FOR_U64_ALIGNMENT 3074 def_bool y 3075 depends on COMPAT 3076 3077endmenu 3078 3079config HAVE_ATOMIC_IOMAP 3080 def_bool y 3081 depends on X86_32 3082 3083source "arch/x86/kvm/Kconfig" 3084 3085source "arch/x86/Kconfig.assembler" 3086