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_USE_CMPXCHG_LOCKREF 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 38config FORCE_DYNAMIC_FTRACE 39 def_bool y 40 depends on X86_32 41 depends on FUNCTION_TRACER 42 select DYNAMIC_FTRACE 43 help 44 We keep the static function tracing (!DYNAMIC_FTRACE) around 45 in order to test the non static function tracing in the 46 generic code, as other architectures still use it. But we 47 only need to keep it around for x86_64. No need to keep it 48 for x86_32. For x86_32, force DYNAMIC_FTRACE. 49# 50# Arch settings 51# 52# ( Note that options that are marked 'if X86_64' could in principle be 53# ported to 32-bit as well. ) 54# 55config X86 56 def_bool y 57 # 58 # Note: keep this list sorted alphabetically 59 # 60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 62 select ARCH_32BIT_OFF_T if X86_32 63 select ARCH_CLOCKSOURCE_INIT 64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 71 select ARCH_HAS_CACHE_LINE_SIZE 72 select ARCH_HAS_CURRENT_STACK_POINTER 73 select ARCH_HAS_DEBUG_VIRTUAL 74 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 75 select ARCH_HAS_DEVMEM_IS_ALLOWED 76 select ARCH_HAS_EARLY_DEBUG if KGDB 77 select ARCH_HAS_ELF_RANDOMIZE 78 select ARCH_HAS_FAST_MULTIPLIER 79 select ARCH_HAS_FORTIFY_SOURCE 80 select ARCH_HAS_GCOV_PROFILE_ALL 81 select ARCH_HAS_KCOV if X86_64 82 select ARCH_HAS_MEM_ENCRYPT 83 select ARCH_HAS_MEMBARRIER_SYNC_CORE 84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 85 select ARCH_HAS_PMEM_API if X86_64 86 select ARCH_HAS_PTE_DEVMAP if X86_64 87 select ARCH_HAS_PTE_SPECIAL 88 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 89 select ARCH_HAS_COPY_MC if X86_64 90 select ARCH_HAS_SET_MEMORY 91 select ARCH_HAS_SET_DIRECT_MAP 92 select ARCH_HAS_STRICT_KERNEL_RWX 93 select ARCH_HAS_STRICT_MODULE_RWX 94 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 95 select ARCH_HAS_SYSCALL_WRAPPER 96 select ARCH_HAS_UBSAN_SANITIZE_ALL 97 select ARCH_HAS_DEBUG_WX 98 select ARCH_HAS_ZONE_DMA_SET if EXPERT 99 select ARCH_HAVE_NMI_SAFE_CMPXCHG 100 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 101 select ARCH_MIGHT_HAVE_PC_PARPORT 102 select ARCH_MIGHT_HAVE_PC_SERIO 103 select ARCH_STACKWALK 104 select ARCH_SUPPORTS_ACPI 105 select ARCH_SUPPORTS_ATOMIC_RMW 106 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 107 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 108 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 109 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 110 select ARCH_SUPPORTS_CFI_CLANG if X86_64 111 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 112 select ARCH_SUPPORTS_LTO_CLANG 113 select ARCH_SUPPORTS_LTO_CLANG_THIN 114 select ARCH_USE_BUILTIN_BSWAP 115 select ARCH_USE_MEMTEST 116 select ARCH_USE_QUEUED_RWLOCKS 117 select ARCH_USE_QUEUED_SPINLOCKS 118 select ARCH_USE_SYM_ANNOTATIONS 119 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 120 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 121 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 122 select ARCH_WANTS_NO_INSTR 123 select ARCH_WANT_GENERAL_HUGETLB 124 select ARCH_WANT_HUGE_PMD_SHARE 125 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64 126 select ARCH_WANT_LD_ORPHAN_WARN 127 select ARCH_WANTS_THP_SWAP if X86_64 128 select ARCH_HAS_PARANOID_L1D_FLUSH 129 select BUILDTIME_TABLE_SORT 130 select CLKEVT_I8253 131 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 132 select CLOCKSOURCE_WATCHDOG 133 select DCACHE_WORD_ACCESS 134 select DYNAMIC_SIGFRAME 135 select EDAC_ATOMIC_SCRUB 136 select EDAC_SUPPORT 137 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 138 select GENERIC_CLOCKEVENTS_MIN_ADJUST 139 select GENERIC_CMOS_UPDATE 140 select GENERIC_CPU_AUTOPROBE 141 select GENERIC_CPU_VULNERABILITIES 142 select GENERIC_EARLY_IOREMAP 143 select GENERIC_ENTRY 144 select GENERIC_IOMAP 145 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 146 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 147 select GENERIC_IRQ_MIGRATION if SMP 148 select GENERIC_IRQ_PROBE 149 select GENERIC_IRQ_RESERVATION_MODE 150 select GENERIC_IRQ_SHOW 151 select GENERIC_PENDING_IRQ if SMP 152 select GENERIC_PTDUMP 153 select GENERIC_SMP_IDLE_THREAD 154 select GENERIC_TIME_VSYSCALL 155 select GENERIC_GETTIMEOFDAY 156 select GENERIC_VDSO_TIME_NS 157 select GUP_GET_PTE_LOW_HIGH if X86_PAE 158 select HARDIRQS_SW_RESEND 159 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 160 select HAVE_ACPI_APEI if ACPI 161 select HAVE_ACPI_APEI_NMI if ACPI 162 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 163 select HAVE_ARCH_AUDITSYSCALL 164 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 165 select HAVE_ARCH_HUGE_VMALLOC if X86_64 166 select HAVE_ARCH_JUMP_LABEL 167 select HAVE_ARCH_JUMP_LABEL_RELATIVE 168 select HAVE_ARCH_KASAN if X86_64 169 select HAVE_ARCH_KASAN_VMALLOC if X86_64 170 select HAVE_ARCH_KFENCE 171 select HAVE_ARCH_KGDB 172 select HAVE_ARCH_MMAP_RND_BITS if MMU 173 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 174 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 175 select HAVE_ARCH_PREL32_RELOCATIONS 176 select HAVE_ARCH_SECCOMP_FILTER 177 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 178 select HAVE_ARCH_STACKLEAK 179 select HAVE_ARCH_TRACEHOOK 180 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 181 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 182 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 183 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 184 select HAVE_ARCH_VMAP_STACK if X86_64 185 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 186 select HAVE_ARCH_WITHIN_STACK_FRAMES 187 select HAVE_ASM_MODVERSIONS 188 select HAVE_CMPXCHG_DOUBLE 189 select HAVE_CMPXCHG_LOCAL 190 select HAVE_CONTEXT_TRACKING_USER if X86_64 191 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 192 select HAVE_C_RECORDMCOUNT 193 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 194 select HAVE_BUILDTIME_MCOUNT_SORT 195 select HAVE_DEBUG_KMEMLEAK 196 select HAVE_DMA_CONTIGUOUS 197 select HAVE_DYNAMIC_FTRACE 198 select HAVE_DYNAMIC_FTRACE_WITH_REGS 199 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 200 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 201 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 202 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 203 select HAVE_EBPF_JIT 204 select HAVE_EFFICIENT_UNALIGNED_ACCESS 205 select HAVE_EISA 206 select HAVE_EXIT_THREAD 207 select HAVE_FAST_GUP 208 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 209 select HAVE_FTRACE_MCOUNT_RECORD 210 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 211 select HAVE_FUNCTION_TRACER 212 select HAVE_GCC_PLUGINS 213 select HAVE_HW_BREAKPOINT 214 select HAVE_IOREMAP_PROT 215 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 216 select HAVE_IRQ_TIME_ACCOUNTING 217 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 218 select HAVE_KERNEL_BZIP2 219 select HAVE_KERNEL_GZIP 220 select HAVE_KERNEL_LZ4 221 select HAVE_KERNEL_LZMA 222 select HAVE_KERNEL_LZO 223 select HAVE_KERNEL_XZ 224 select HAVE_KERNEL_ZSTD 225 select HAVE_KPROBES 226 select HAVE_KPROBES_ON_FTRACE 227 select HAVE_FUNCTION_ERROR_INJECTION 228 select HAVE_KRETPROBES 229 select HAVE_RETHOOK 230 select HAVE_KVM 231 select HAVE_LIVEPATCH if X86_64 232 select HAVE_MIXED_BREAKPOINTS_REGS 233 select HAVE_MOD_ARCH_SPECIFIC 234 select HAVE_MOVE_PMD 235 select HAVE_MOVE_PUD 236 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 237 select HAVE_NMI 238 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 239 select HAVE_OBJTOOL if X86_64 240 select HAVE_OPTPROBES 241 select HAVE_PCSPKR_PLATFORM 242 select HAVE_PERF_EVENTS 243 select HAVE_PERF_EVENTS_NMI 244 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 245 select HAVE_PCI 246 select HAVE_PERF_REGS 247 select HAVE_PERF_USER_STACK_DUMP 248 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 249 select MMU_GATHER_MERGE_VMAS 250 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 251 select HAVE_REGS_AND_STACK_ACCESS_API 252 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 253 select HAVE_FUNCTION_ARG_ACCESS_API 254 select HAVE_SETUP_PER_CPU_AREA 255 select HAVE_SOFTIRQ_ON_OWN_STACK 256 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 257 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 258 select HAVE_STATIC_CALL 259 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 260 select HAVE_PREEMPT_DYNAMIC_CALL 261 select HAVE_RSEQ 262 select HAVE_RUST if X86_64 263 select HAVE_SYSCALL_TRACEPOINTS 264 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 265 select HAVE_UNSTABLE_SCHED_CLOCK 266 select HAVE_USER_RETURN_NOTIFIER 267 select HAVE_GENERIC_VDSO 268 select HOTPLUG_SMT if SMP 269 select IRQ_FORCED_THREADING 270 select NEED_PER_CPU_EMBED_FIRST_CHUNK 271 select NEED_PER_CPU_PAGE_FIRST_CHUNK 272 select NEED_SG_DMA_LENGTH 273 select PCI_DOMAINS if PCI 274 select PCI_LOCKLESS_CONFIG if PCI 275 select PERF_EVENTS 276 select RTC_LIB 277 select RTC_MC146818_LIB 278 select SPARSE_IRQ 279 select SRCU 280 select SYSCTL_EXCEPTION_TRACE 281 select THREAD_INFO_IN_TASK 282 select TRACE_IRQFLAGS_SUPPORT 283 select TRACE_IRQFLAGS_NMI_SUPPORT 284 select USER_STACKTRACE_SUPPORT 285 select HAVE_ARCH_KCSAN if X86_64 286 select X86_FEATURE_NAMES if PROC_FS 287 select PROC_PID_ARCH_STATUS if PROC_FS 288 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 289 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 290 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 291 292config INSTRUCTION_DECODER 293 def_bool y 294 depends on KPROBES || PERF_EVENTS || UPROBES 295 296config OUTPUT_FORMAT 297 string 298 default "elf32-i386" if X86_32 299 default "elf64-x86-64" if X86_64 300 301config LOCKDEP_SUPPORT 302 def_bool y 303 304config STACKTRACE_SUPPORT 305 def_bool y 306 307config MMU 308 def_bool y 309 310config ARCH_MMAP_RND_BITS_MIN 311 default 28 if 64BIT 312 default 8 313 314config ARCH_MMAP_RND_BITS_MAX 315 default 32 if 64BIT 316 default 16 317 318config ARCH_MMAP_RND_COMPAT_BITS_MIN 319 default 8 320 321config ARCH_MMAP_RND_COMPAT_BITS_MAX 322 default 16 323 324config SBUS 325 bool 326 327config GENERIC_ISA_DMA 328 def_bool y 329 depends on ISA_DMA_API 330 331config GENERIC_BUG 332 def_bool y 333 depends on BUG 334 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 335 336config GENERIC_BUG_RELATIVE_POINTERS 337 bool 338 339config ARCH_MAY_HAVE_PC_FDC 340 def_bool y 341 depends on ISA_DMA_API 342 343config GENERIC_CALIBRATE_DELAY 344 def_bool y 345 346config ARCH_HAS_CPU_RELAX 347 def_bool y 348 349config ARCH_HIBERNATION_POSSIBLE 350 def_bool y 351 352config ARCH_NR_GPIO 353 int 354 default 1024 if X86_64 355 default 512 356 357config ARCH_SUSPEND_POSSIBLE 358 def_bool y 359 360config AUDIT_ARCH 361 def_bool y if X86_64 362 363config KASAN_SHADOW_OFFSET 364 hex 365 depends on KASAN 366 default 0xdffffc0000000000 367 368config HAVE_INTEL_TXT 369 def_bool y 370 depends on INTEL_IOMMU && ACPI 371 372config X86_32_SMP 373 def_bool y 374 depends on X86_32 && SMP 375 376config X86_64_SMP 377 def_bool y 378 depends on X86_64 && SMP 379 380config ARCH_SUPPORTS_UPROBES 381 def_bool y 382 383config FIX_EARLYCON_MEM 384 def_bool y 385 386config DYNAMIC_PHYSICAL_MASK 387 bool 388 389config PGTABLE_LEVELS 390 int 391 default 5 if X86_5LEVEL 392 default 4 if X86_64 393 default 3 if X86_PAE 394 default 2 395 396config CC_HAS_SANE_STACKPROTECTOR 397 bool 398 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 399 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 400 help 401 We have to make sure stack protector is unconditionally disabled if 402 the compiler produces broken code or if it does not let us control 403 the segment on 32-bit kernels. 404 405menu "Processor type and features" 406 407config SMP 408 bool "Symmetric multi-processing support" 409 help 410 This enables support for systems with more than one CPU. If you have 411 a system with only one CPU, say N. If you have a system with more 412 than one CPU, say Y. 413 414 If you say N here, the kernel will run on uni- and multiprocessor 415 machines, but will use only one CPU of a multiprocessor machine. If 416 you say Y here, the kernel will run on many, but not all, 417 uniprocessor machines. On a uniprocessor machine, the kernel 418 will run faster if you say N here. 419 420 Note that if you say Y here and choose architecture "586" or 421 "Pentium" under "Processor family", the kernel will not work on 486 422 architectures. Similarly, multiprocessor kernels for the "PPro" 423 architecture may not work on all Pentium based boards. 424 425 People using multiprocessor machines who say Y here should also say 426 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 427 Management" code will be disabled if you say Y here. 428 429 See also <file:Documentation/x86/i386/IO-APIC.rst>, 430 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 431 <http://www.tldp.org/docs.html#howto>. 432 433 If you don't know what to do here, say N. 434 435config X86_FEATURE_NAMES 436 bool "Processor feature human-readable names" if EMBEDDED 437 default y 438 help 439 This option compiles in a table of x86 feature bits and corresponding 440 names. This is required to support /proc/cpuinfo and a few kernel 441 messages. You can disable this to save space, at the expense of 442 making those few kernel messages show numeric feature bits instead. 443 444 If in doubt, say Y. 445 446config X86_X2APIC 447 bool "Support x2apic" 448 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 449 help 450 This enables x2apic support on CPUs that have this feature. 451 452 This allows 32-bit apic IDs (so it can support very large systems), 453 and accesses the local apic via MSRs not via mmio. 454 455 Some Intel systems circa 2022 and later are locked into x2APIC mode 456 and can not fall back to the legacy APIC modes if SGX or TDX are 457 enabled in the BIOS. They will be unable to boot without enabling 458 this option. 459 460 If you don't know what to do here, say N. 461 462config X86_MPPARSE 463 bool "Enable MPS table" if ACPI 464 default y 465 depends on X86_LOCAL_APIC 466 help 467 For old smp systems that do not have proper acpi support. Newer systems 468 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 469 470config GOLDFISH 471 def_bool y 472 depends on X86_GOLDFISH 473 474config X86_CPU_RESCTRL 475 bool "x86 CPU resource control support" 476 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 477 select KERNFS 478 select PROC_CPU_RESCTRL if PROC_FS 479 help 480 Enable x86 CPU resource control support. 481 482 Provide support for the allocation and monitoring of system resources 483 usage by the CPU. 484 485 Intel calls this Intel Resource Director Technology 486 (Intel(R) RDT). More information about RDT can be found in the 487 Intel x86 Architecture Software Developer Manual. 488 489 AMD calls this AMD Platform Quality of Service (AMD QoS). 490 More information about AMD QoS can be found in the AMD64 Technology 491 Platform Quality of Service Extensions manual. 492 493 Say N if unsure. 494 495if X86_32 496config X86_BIGSMP 497 bool "Support for big SMP systems with more than 8 CPUs" 498 depends on SMP 499 help 500 This option is needed for the systems that have more than 8 CPUs. 501 502config X86_EXTENDED_PLATFORM 503 bool "Support for extended (non-PC) x86 platforms" 504 default y 505 help 506 If you disable this option then the kernel will only support 507 standard PC platforms. (which covers the vast majority of 508 systems out there.) 509 510 If you enable this option then you'll be able to select support 511 for the following (non-PC) 32 bit x86 platforms: 512 Goldfish (Android emulator) 513 AMD Elan 514 RDC R-321x SoC 515 SGI 320/540 (Visual Workstation) 516 STA2X11-based (e.g. Northville) 517 Moorestown MID devices 518 519 If you have one of these systems, or if you want to build a 520 generic distribution kernel, say Y here - otherwise say N. 521endif # X86_32 522 523if X86_64 524config X86_EXTENDED_PLATFORM 525 bool "Support for extended (non-PC) x86 platforms" 526 default y 527 help 528 If you disable this option then the kernel will only support 529 standard PC platforms. (which covers the vast majority of 530 systems out there.) 531 532 If you enable this option then you'll be able to select support 533 for the following (non-PC) 64 bit x86 platforms: 534 Numascale NumaChip 535 ScaleMP vSMP 536 SGI Ultraviolet 537 538 If you have one of these systems, or if you want to build a 539 generic distribution kernel, say Y here - otherwise say N. 540endif # X86_64 541# This is an alphabetically sorted list of 64 bit extended platforms 542# Please maintain the alphabetic order if and when there are additions 543config X86_NUMACHIP 544 bool "Numascale NumaChip" 545 depends on X86_64 546 depends on X86_EXTENDED_PLATFORM 547 depends on NUMA 548 depends on SMP 549 depends on X86_X2APIC 550 depends on PCI_MMCONFIG 551 help 552 Adds support for Numascale NumaChip large-SMP systems. Needed to 553 enable more than ~168 cores. 554 If you don't have one of these, you should say N here. 555 556config X86_VSMP 557 bool "ScaleMP vSMP" 558 select HYPERVISOR_GUEST 559 select PARAVIRT 560 depends on X86_64 && PCI 561 depends on X86_EXTENDED_PLATFORM 562 depends on SMP 563 help 564 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 565 supposed to run on these EM64T-based machines. Only choose this option 566 if you have one of these machines. 567 568config X86_UV 569 bool "SGI Ultraviolet" 570 depends on X86_64 571 depends on X86_EXTENDED_PLATFORM 572 depends on NUMA 573 depends on EFI 574 depends on KEXEC_CORE 575 depends on X86_X2APIC 576 depends on PCI 577 help 578 This option is needed in order to support SGI Ultraviolet systems. 579 If you don't have one of these, you should say N here. 580 581# Following is an alphabetically sorted list of 32 bit extended platforms 582# Please maintain the alphabetic order if and when there are additions 583 584config X86_GOLDFISH 585 bool "Goldfish (Virtual Platform)" 586 depends on X86_EXTENDED_PLATFORM 587 help 588 Enable support for the Goldfish virtual platform used primarily 589 for Android development. Unless you are building for the Android 590 Goldfish emulator say N here. 591 592config X86_INTEL_CE 593 bool "CE4100 TV platform" 594 depends on PCI 595 depends on PCI_GODIRECT 596 depends on X86_IO_APIC 597 depends on X86_32 598 depends on X86_EXTENDED_PLATFORM 599 select X86_REBOOTFIXUPS 600 select OF 601 select OF_EARLY_FLATTREE 602 help 603 Select for the Intel CE media processor (CE4100) SOC. 604 This option compiles in support for the CE4100 SOC for settop 605 boxes and media devices. 606 607config X86_INTEL_MID 608 bool "Intel MID platform support" 609 depends on X86_EXTENDED_PLATFORM 610 depends on X86_PLATFORM_DEVICES 611 depends on PCI 612 depends on X86_64 || (PCI_GOANY && X86_32) 613 depends on X86_IO_APIC 614 select I2C 615 select DW_APB_TIMER 616 select INTEL_SCU_PCI 617 help 618 Select to build a kernel capable of supporting Intel MID (Mobile 619 Internet Device) platform systems which do not have the PCI legacy 620 interfaces. If you are building for a PC class system say N here. 621 622 Intel MID platforms are based on an Intel processor and chipset which 623 consume less power than most of the x86 derivatives. 624 625config X86_INTEL_QUARK 626 bool "Intel Quark platform support" 627 depends on X86_32 628 depends on X86_EXTENDED_PLATFORM 629 depends on X86_PLATFORM_DEVICES 630 depends on X86_TSC 631 depends on PCI 632 depends on PCI_GOANY 633 depends on X86_IO_APIC 634 select IOSF_MBI 635 select INTEL_IMR 636 select COMMON_CLK 637 help 638 Select to include support for Quark X1000 SoC. 639 Say Y here if you have a Quark based system such as the Arduino 640 compatible Intel Galileo. 641 642config X86_INTEL_LPSS 643 bool "Intel Low Power Subsystem Support" 644 depends on X86 && ACPI && PCI 645 select COMMON_CLK 646 select PINCTRL 647 select IOSF_MBI 648 help 649 Select to build support for Intel Low Power Subsystem such as 650 found on Intel Lynxpoint PCH. Selecting this option enables 651 things like clock tree (common clock framework) and pincontrol 652 which are needed by the LPSS peripheral drivers. 653 654config X86_AMD_PLATFORM_DEVICE 655 bool "AMD ACPI2Platform devices support" 656 depends on ACPI 657 select COMMON_CLK 658 select PINCTRL 659 help 660 Select to interpret AMD specific ACPI device to platform device 661 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 662 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 663 implemented under PINCTRL subsystem. 664 665config IOSF_MBI 666 tristate "Intel SoC IOSF Sideband support for SoC platforms" 667 depends on PCI 668 help 669 This option enables sideband register access support for Intel SoC 670 platforms. On these platforms the IOSF sideband is used in lieu of 671 MSR's for some register accesses, mostly but not limited to thermal 672 and power. Drivers may query the availability of this device to 673 determine if they need the sideband in order to work on these 674 platforms. The sideband is available on the following SoC products. 675 This list is not meant to be exclusive. 676 - BayTrail 677 - Braswell 678 - Quark 679 680 You should say Y if you are running a kernel on one of these SoC's. 681 682config IOSF_MBI_DEBUG 683 bool "Enable IOSF sideband access through debugfs" 684 depends on IOSF_MBI && DEBUG_FS 685 help 686 Select this option to expose the IOSF sideband access registers (MCR, 687 MDR, MCRX) through debugfs to write and read register information from 688 different units on the SoC. This is most useful for obtaining device 689 state information for debug and analysis. As this is a general access 690 mechanism, users of this option would have specific knowledge of the 691 device they want to access. 692 693 If you don't require the option or are in doubt, say N. 694 695config X86_RDC321X 696 bool "RDC R-321x SoC" 697 depends on X86_32 698 depends on X86_EXTENDED_PLATFORM 699 select M486 700 select X86_REBOOTFIXUPS 701 help 702 This option is needed for RDC R-321x system-on-chip, also known 703 as R-8610-(G). 704 If you don't have one of these chips, you should say N here. 705 706config X86_32_NON_STANDARD 707 bool "Support non-standard 32-bit SMP architectures" 708 depends on X86_32 && SMP 709 depends on X86_EXTENDED_PLATFORM 710 help 711 This option compiles in the bigsmp and STA2X11 default 712 subarchitectures. It is intended for a generic binary 713 kernel. If you select them all, kernel will probe it one by 714 one and will fallback to default. 715 716# Alphabetically sorted list of Non standard 32 bit platforms 717 718config X86_SUPPORTS_MEMORY_FAILURE 719 def_bool y 720 # MCE code calls memory_failure(): 721 depends on X86_MCE 722 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 723 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 724 depends on X86_64 || !SPARSEMEM 725 select ARCH_SUPPORTS_MEMORY_FAILURE 726 727config STA2X11 728 bool "STA2X11 Companion Chip Support" 729 depends on X86_32_NON_STANDARD && PCI 730 select SWIOTLB 731 select MFD_STA2X11 732 select GPIOLIB 733 help 734 This adds support for boards based on the STA2X11 IO-Hub, 735 a.k.a. "ConneXt". The chip is used in place of the standard 736 PC chipset, so all "standard" peripherals are missing. If this 737 option is selected the kernel will still be able to boot on 738 standard PC machines. 739 740config X86_32_IRIS 741 tristate "Eurobraille/Iris poweroff module" 742 depends on X86_32 743 help 744 The Iris machines from EuroBraille do not have APM or ACPI support 745 to shut themselves down properly. A special I/O sequence is 746 needed to do so, which is what this module does at 747 kernel shutdown. 748 749 This is only for Iris machines from EuroBraille. 750 751 If unused, say N. 752 753config SCHED_OMIT_FRAME_POINTER 754 def_bool y 755 prompt "Single-depth WCHAN output" 756 depends on X86 757 help 758 Calculate simpler /proc/<PID>/wchan values. If this option 759 is disabled then wchan values will recurse back to the 760 caller function. This provides more accurate wchan values, 761 at the expense of slightly more scheduling overhead. 762 763 If in doubt, say "Y". 764 765menuconfig HYPERVISOR_GUEST 766 bool "Linux guest support" 767 help 768 Say Y here to enable options for running Linux under various hyper- 769 visors. This option enables basic hypervisor detection and platform 770 setup. 771 772 If you say N, all options in this submenu will be skipped and 773 disabled, and Linux guest support won't be built in. 774 775if HYPERVISOR_GUEST 776 777config PARAVIRT 778 bool "Enable paravirtualization code" 779 depends on HAVE_STATIC_CALL 780 help 781 This changes the kernel so it can modify itself when it is run 782 under a hypervisor, potentially improving performance significantly 783 over full virtualization. However, when run without a hypervisor 784 the kernel is theoretically slower and slightly larger. 785 786config PARAVIRT_XXL 787 bool 788 789config PARAVIRT_DEBUG 790 bool "paravirt-ops debugging" 791 depends on PARAVIRT && DEBUG_KERNEL 792 help 793 Enable to debug paravirt_ops internals. Specifically, BUG if 794 a paravirt_op is missing when it is called. 795 796config PARAVIRT_SPINLOCKS 797 bool "Paravirtualization layer for spinlocks" 798 depends on PARAVIRT && SMP 799 help 800 Paravirtualized spinlocks allow a pvops backend to replace the 801 spinlock implementation with something virtualization-friendly 802 (for example, block the virtual CPU rather than spinning). 803 804 It has a minimal impact on native kernels and gives a nice performance 805 benefit on paravirtualized KVM / Xen kernels. 806 807 If you are unsure how to answer this question, answer Y. 808 809config X86_HV_CALLBACK_VECTOR 810 def_bool n 811 812source "arch/x86/xen/Kconfig" 813 814config KVM_GUEST 815 bool "KVM Guest support (including kvmclock)" 816 depends on PARAVIRT 817 select PARAVIRT_CLOCK 818 select ARCH_CPUIDLE_HALTPOLL 819 select X86_HV_CALLBACK_VECTOR 820 default y 821 help 822 This option enables various optimizations for running under the KVM 823 hypervisor. It includes a paravirtualized clock, so that instead 824 of relying on a PIT (or probably other) emulation by the 825 underlying device model, the host provides the guest with 826 timing infrastructure such as time of day, and system time 827 828config ARCH_CPUIDLE_HALTPOLL 829 def_bool n 830 prompt "Disable host haltpoll when loading haltpoll driver" 831 help 832 If virtualized under KVM, disable host haltpoll. 833 834config PVH 835 bool "Support for running PVH guests" 836 help 837 This option enables the PVH entry point for guest virtual machines 838 as specified in the x86/HVM direct boot ABI. 839 840config PARAVIRT_TIME_ACCOUNTING 841 bool "Paravirtual steal time accounting" 842 depends on PARAVIRT 843 help 844 Select this option to enable fine granularity task steal time 845 accounting. Time spent executing other tasks in parallel with 846 the current vCPU is discounted from the vCPU power. To account for 847 that, there can be a small performance impact. 848 849 If in doubt, say N here. 850 851config PARAVIRT_CLOCK 852 bool 853 854config JAILHOUSE_GUEST 855 bool "Jailhouse non-root cell support" 856 depends on X86_64 && PCI 857 select X86_PM_TIMER 858 help 859 This option allows to run Linux as guest in a Jailhouse non-root 860 cell. You can leave this option disabled if you only want to start 861 Jailhouse and run Linux afterwards in the root cell. 862 863config ACRN_GUEST 864 bool "ACRN Guest support" 865 depends on X86_64 866 select X86_HV_CALLBACK_VECTOR 867 help 868 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 869 a flexible, lightweight reference open-source hypervisor, built with 870 real-time and safety-criticality in mind. It is built for embedded 871 IOT with small footprint and real-time features. More details can be 872 found in https://projectacrn.org/. 873 874config INTEL_TDX_GUEST 875 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 876 depends on X86_64 && CPU_SUP_INTEL 877 depends on X86_X2APIC 878 select ARCH_HAS_CC_PLATFORM 879 select X86_MEM_ENCRYPT 880 select X86_MCE 881 help 882 Support running as a guest under Intel TDX. Without this support, 883 the guest kernel can not boot or run under TDX. 884 TDX includes memory encryption and integrity capabilities 885 which protect the confidentiality and integrity of guest 886 memory contents and CPU state. TDX guests are protected from 887 some attacks from the VMM. 888 889endif # HYPERVISOR_GUEST 890 891source "arch/x86/Kconfig.cpu" 892 893config HPET_TIMER 894 def_bool X86_64 895 prompt "HPET Timer Support" if X86_32 896 help 897 Use the IA-PC HPET (High Precision Event Timer) to manage 898 time in preference to the PIT and RTC, if a HPET is 899 present. 900 HPET is the next generation timer replacing legacy 8254s. 901 The HPET provides a stable time base on SMP 902 systems, unlike the TSC, but it is more expensive to access, 903 as it is off-chip. The interface used is documented 904 in the HPET spec, revision 1. 905 906 You can safely choose Y here. However, HPET will only be 907 activated if the platform and the BIOS support this feature. 908 Otherwise the 8254 will be used for timing services. 909 910 Choose N to continue using the legacy 8254 timer. 911 912config HPET_EMULATE_RTC 913 def_bool y 914 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 915 916# Mark as expert because too many people got it wrong. 917# The code disables itself when not needed. 918config DMI 919 default y 920 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 921 bool "Enable DMI scanning" if EXPERT 922 help 923 Enabled scanning of DMI to identify machine quirks. Say Y 924 here unless you have verified that your setup is not 925 affected by entries in the DMI blacklist. Required by PNP 926 BIOS code. 927 928config GART_IOMMU 929 bool "Old AMD GART IOMMU support" 930 select DMA_OPS 931 select IOMMU_HELPER 932 select SWIOTLB 933 depends on X86_64 && PCI && AMD_NB 934 help 935 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 936 GART based hardware IOMMUs. 937 938 The GART supports full DMA access for devices with 32-bit access 939 limitations, on systems with more than 3 GB. This is usually needed 940 for USB, sound, many IDE/SATA chipsets and some other devices. 941 942 Newer systems typically have a modern AMD IOMMU, supported via 943 the CONFIG_AMD_IOMMU=y config option. 944 945 In normal configurations this driver is only active when needed: 946 there's more than 3 GB of memory and the system contains a 947 32-bit limited device. 948 949 If unsure, say Y. 950 951config BOOT_VESA_SUPPORT 952 bool 953 help 954 If true, at least one selected framebuffer driver can take advantage 955 of VESA video modes set at an early boot stage via the vga= parameter. 956 957config MAXSMP 958 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 959 depends on X86_64 && SMP && DEBUG_KERNEL 960 select CPUMASK_OFFSTACK 961 help 962 Enable maximum number of CPUS and NUMA Nodes for this architecture. 963 If unsure, say N. 964 965# 966# The maximum number of CPUs supported: 967# 968# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 969# and which can be configured interactively in the 970# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 971# 972# The ranges are different on 32-bit and 64-bit kernels, depending on 973# hardware capabilities and scalability features of the kernel. 974# 975# ( If MAXSMP is enabled we just use the highest possible value and disable 976# interactive configuration. ) 977# 978 979config NR_CPUS_RANGE_BEGIN 980 int 981 default NR_CPUS_RANGE_END if MAXSMP 982 default 1 if !SMP 983 default 2 984 985config NR_CPUS_RANGE_END 986 int 987 depends on X86_32 988 default 64 if SMP && X86_BIGSMP 989 default 8 if SMP && !X86_BIGSMP 990 default 1 if !SMP 991 992config NR_CPUS_RANGE_END 993 int 994 depends on X86_64 995 default 8192 if SMP && CPUMASK_OFFSTACK 996 default 512 if SMP && !CPUMASK_OFFSTACK 997 default 1 if !SMP 998 999config NR_CPUS_DEFAULT 1000 int 1001 depends on X86_32 1002 default 32 if X86_BIGSMP 1003 default 8 if SMP 1004 default 1 if !SMP 1005 1006config NR_CPUS_DEFAULT 1007 int 1008 depends on X86_64 1009 default 8192 if MAXSMP 1010 default 64 if SMP 1011 default 1 if !SMP 1012 1013config NR_CPUS 1014 int "Maximum number of CPUs" if SMP && !MAXSMP 1015 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1016 default NR_CPUS_DEFAULT 1017 help 1018 This allows you to specify the maximum number of CPUs which this 1019 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1020 supported value is 8192, otherwise the maximum value is 512. The 1021 minimum value which makes sense is 2. 1022 1023 This is purely to save memory: each supported CPU adds about 8KB 1024 to the kernel image. 1025 1026config SCHED_CLUSTER 1027 bool "Cluster scheduler support" 1028 depends on SMP 1029 default y 1030 help 1031 Cluster scheduler support improves the CPU scheduler's decision 1032 making when dealing with machines that have clusters of CPUs. 1033 Cluster usually means a couple of CPUs which are placed closely 1034 by sharing mid-level caches, last-level cache tags or internal 1035 busses. 1036 1037config SCHED_SMT 1038 def_bool y if SMP 1039 1040config SCHED_MC 1041 def_bool y 1042 prompt "Multi-core scheduler support" 1043 depends on SMP 1044 help 1045 Multi-core scheduler support improves the CPU scheduler's decision 1046 making when dealing with multi-core CPU chips at a cost of slightly 1047 increased overhead in some places. If unsure say N here. 1048 1049config SCHED_MC_PRIO 1050 bool "CPU core priorities scheduler support" 1051 depends on SCHED_MC && CPU_SUP_INTEL 1052 select X86_INTEL_PSTATE 1053 select CPU_FREQ 1054 default y 1055 help 1056 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1057 core ordering determined at manufacturing time, which allows 1058 certain cores to reach higher turbo frequencies (when running 1059 single threaded workloads) than others. 1060 1061 Enabling this kernel feature teaches the scheduler about 1062 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1063 scheduler's CPU selection logic accordingly, so that higher 1064 overall system performance can be achieved. 1065 1066 This feature will have no effect on CPUs without this feature. 1067 1068 If unsure say Y here. 1069 1070config UP_LATE_INIT 1071 def_bool y 1072 depends on !SMP && X86_LOCAL_APIC 1073 1074config X86_UP_APIC 1075 bool "Local APIC support on uniprocessors" if !PCI_MSI 1076 default PCI_MSI 1077 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1078 help 1079 A local APIC (Advanced Programmable Interrupt Controller) is an 1080 integrated interrupt controller in the CPU. If you have a single-CPU 1081 system which has a processor with a local APIC, you can say Y here to 1082 enable and use it. If you say Y here even though your machine doesn't 1083 have a local APIC, then the kernel will still run with no slowdown at 1084 all. The local APIC supports CPU-generated self-interrupts (timer, 1085 performance counters), and the NMI watchdog which detects hard 1086 lockups. 1087 1088config X86_UP_IOAPIC 1089 bool "IO-APIC support on uniprocessors" 1090 depends on X86_UP_APIC 1091 help 1092 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1093 SMP-capable replacement for PC-style interrupt controllers. Most 1094 SMP systems and many recent uniprocessor systems have one. 1095 1096 If you have a single-CPU system with an IO-APIC, you can say Y here 1097 to use it. If you say Y here even though your machine doesn't have 1098 an IO-APIC, then the kernel will still run with no slowdown at all. 1099 1100config X86_LOCAL_APIC 1101 def_bool y 1102 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1103 select IRQ_DOMAIN_HIERARCHY 1104 select PCI_MSI_IRQ_DOMAIN if PCI_MSI 1105 1106config X86_IO_APIC 1107 def_bool y 1108 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1109 1110config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1111 bool "Reroute for broken boot IRQs" 1112 depends on X86_IO_APIC 1113 help 1114 This option enables a workaround that fixes a source of 1115 spurious interrupts. This is recommended when threaded 1116 interrupt handling is used on systems where the generation of 1117 superfluous "boot interrupts" cannot be disabled. 1118 1119 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1120 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1121 kernel does during interrupt handling). On chipsets where this 1122 boot IRQ generation cannot be disabled, this workaround keeps 1123 the original IRQ line masked so that only the equivalent "boot 1124 IRQ" is delivered to the CPUs. The workaround also tells the 1125 kernel to set up the IRQ handler on the boot IRQ line. In this 1126 way only one interrupt is delivered to the kernel. Otherwise 1127 the spurious second interrupt may cause the kernel to bring 1128 down (vital) interrupt lines. 1129 1130 Only affects "broken" chipsets. Interrupt sharing may be 1131 increased on these systems. 1132 1133config X86_MCE 1134 bool "Machine Check / overheating reporting" 1135 select GENERIC_ALLOCATOR 1136 default y 1137 help 1138 Machine Check support allows the processor to notify the 1139 kernel if it detects a problem (e.g. overheating, data corruption). 1140 The action the kernel takes depends on the severity of the problem, 1141 ranging from warning messages to halting the machine. 1142 1143config X86_MCELOG_LEGACY 1144 bool "Support for deprecated /dev/mcelog character device" 1145 depends on X86_MCE 1146 help 1147 Enable support for /dev/mcelog which is needed by the old mcelog 1148 userspace logging daemon. Consider switching to the new generation 1149 rasdaemon solution. 1150 1151config X86_MCE_INTEL 1152 def_bool y 1153 prompt "Intel MCE features" 1154 depends on X86_MCE && X86_LOCAL_APIC 1155 help 1156 Additional support for intel specific MCE features such as 1157 the thermal monitor. 1158 1159config X86_MCE_AMD 1160 def_bool y 1161 prompt "AMD MCE features" 1162 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1163 help 1164 Additional support for AMD specific MCE features such as 1165 the DRAM Error Threshold. 1166 1167config X86_ANCIENT_MCE 1168 bool "Support for old Pentium 5 / WinChip machine checks" 1169 depends on X86_32 && X86_MCE 1170 help 1171 Include support for machine check handling on old Pentium 5 or WinChip 1172 systems. These typically need to be enabled explicitly on the command 1173 line. 1174 1175config X86_MCE_THRESHOLD 1176 depends on X86_MCE_AMD || X86_MCE_INTEL 1177 def_bool y 1178 1179config X86_MCE_INJECT 1180 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1181 tristate "Machine check injector support" 1182 help 1183 Provide support for injecting machine checks for testing purposes. 1184 If you don't know what a machine check is and you don't do kernel 1185 QA it is safe to say n. 1186 1187source "arch/x86/events/Kconfig" 1188 1189config X86_LEGACY_VM86 1190 bool "Legacy VM86 support" 1191 depends on X86_32 1192 help 1193 This option allows user programs to put the CPU into V8086 1194 mode, which is an 80286-era approximation of 16-bit real mode. 1195 1196 Some very old versions of X and/or vbetool require this option 1197 for user mode setting. Similarly, DOSEMU will use it if 1198 available to accelerate real mode DOS programs. However, any 1199 recent version of DOSEMU, X, or vbetool should be fully 1200 functional even without kernel VM86 support, as they will all 1201 fall back to software emulation. Nevertheless, if you are using 1202 a 16-bit DOS program where 16-bit performance matters, vm86 1203 mode might be faster than emulation and you might want to 1204 enable this option. 1205 1206 Note that any app that works on a 64-bit kernel is unlikely to 1207 need this option, as 64-bit kernels don't, and can't, support 1208 V8086 mode. This option is also unrelated to 16-bit protected 1209 mode and is not needed to run most 16-bit programs under Wine. 1210 1211 Enabling this option increases the complexity of the kernel 1212 and slows down exception handling a tiny bit. 1213 1214 If unsure, say N here. 1215 1216config VM86 1217 bool 1218 default X86_LEGACY_VM86 1219 1220config X86_16BIT 1221 bool "Enable support for 16-bit segments" if EXPERT 1222 default y 1223 depends on MODIFY_LDT_SYSCALL 1224 help 1225 This option is required by programs like Wine to run 16-bit 1226 protected mode legacy code on x86 processors. Disabling 1227 this option saves about 300 bytes on i386, or around 6K text 1228 plus 16K runtime memory on x86-64, 1229 1230config X86_ESPFIX32 1231 def_bool y 1232 depends on X86_16BIT && X86_32 1233 1234config X86_ESPFIX64 1235 def_bool y 1236 depends on X86_16BIT && X86_64 1237 1238config X86_VSYSCALL_EMULATION 1239 bool "Enable vsyscall emulation" if EXPERT 1240 default y 1241 depends on X86_64 1242 help 1243 This enables emulation of the legacy vsyscall page. Disabling 1244 it is roughly equivalent to booting with vsyscall=none, except 1245 that it will also disable the helpful warning if a program 1246 tries to use a vsyscall. With this option set to N, offending 1247 programs will just segfault, citing addresses of the form 1248 0xffffffffff600?00. 1249 1250 This option is required by many programs built before 2013, and 1251 care should be used even with newer programs if set to N. 1252 1253 Disabling this option saves about 7K of kernel size and 1254 possibly 4K of additional runtime pagetable memory. 1255 1256config X86_IOPL_IOPERM 1257 bool "IOPERM and IOPL Emulation" 1258 default y 1259 help 1260 This enables the ioperm() and iopl() syscalls which are necessary 1261 for legacy applications. 1262 1263 Legacy IOPL support is an overbroad mechanism which allows user 1264 space aside of accessing all 65536 I/O ports also to disable 1265 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1266 capabilities and permission from potentially active security 1267 modules. 1268 1269 The emulation restricts the functionality of the syscall to 1270 only allowing the full range I/O port access, but prevents the 1271 ability to disable interrupts from user space which would be 1272 granted if the hardware IOPL mechanism would be used. 1273 1274config TOSHIBA 1275 tristate "Toshiba Laptop support" 1276 depends on X86_32 1277 help 1278 This adds a driver to safely access the System Management Mode of 1279 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1280 not work on models with a Phoenix BIOS. The System Management Mode 1281 is used to set the BIOS and power saving options on Toshiba portables. 1282 1283 For information on utilities to make use of this driver see the 1284 Toshiba Linux utilities web site at: 1285 <http://www.buzzard.org.uk/toshiba/>. 1286 1287 Say Y if you intend to run this kernel on a Toshiba portable. 1288 Say N otherwise. 1289 1290config X86_REBOOTFIXUPS 1291 bool "Enable X86 board specific fixups for reboot" 1292 depends on X86_32 1293 help 1294 This enables chipset and/or board specific fixups to be done 1295 in order to get reboot to work correctly. This is only needed on 1296 some combinations of hardware and BIOS. The symptom, for which 1297 this config is intended, is when reboot ends with a stalled/hung 1298 system. 1299 1300 Currently, the only fixup is for the Geode machines using 1301 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1302 1303 Say Y if you want to enable the fixup. Currently, it's safe to 1304 enable this option even if you don't need it. 1305 Say N otherwise. 1306 1307config MICROCODE 1308 bool "CPU microcode loading support" 1309 default y 1310 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1311 help 1312 If you say Y here, you will be able to update the microcode on 1313 Intel and AMD processors. The Intel support is for the IA32 family, 1314 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1315 AMD support is for families 0x10 and later. You will obviously need 1316 the actual microcode binary data itself which is not shipped with 1317 the Linux kernel. 1318 1319 The preferred method to load microcode from a detached initrd is described 1320 in Documentation/x86/microcode.rst. For that you need to enable 1321 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1322 initrd for microcode blobs. 1323 1324 In addition, you can build the microcode into the kernel. For that you 1325 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1326 config option. 1327 1328config MICROCODE_INTEL 1329 bool "Intel microcode loading support" 1330 depends on CPU_SUP_INTEL && MICROCODE 1331 default MICROCODE 1332 help 1333 This options enables microcode patch loading support for Intel 1334 processors. 1335 1336 For the current Intel microcode data package go to 1337 <https://downloadcenter.intel.com> and search for 1338 'Linux Processor Microcode Data File'. 1339 1340config MICROCODE_AMD 1341 bool "AMD microcode loading support" 1342 depends on CPU_SUP_AMD && MICROCODE 1343 help 1344 If you select this option, microcode patch loading support for AMD 1345 processors will be enabled. 1346 1347config MICROCODE_LATE_LOADING 1348 bool "Late microcode loading (DANGEROUS)" 1349 default n 1350 depends on MICROCODE 1351 help 1352 Loading microcode late, when the system is up and executing instructions 1353 is a tricky business and should be avoided if possible. Just the sequence 1354 of synchronizing all cores and SMT threads is one fragile dance which does 1355 not guarantee that cores might not softlock after the loading. Therefore, 1356 use this at your own risk. Late loading taints the kernel too. 1357 1358config X86_MSR 1359 tristate "/dev/cpu/*/msr - Model-specific register support" 1360 help 1361 This device gives privileged processes access to the x86 1362 Model-Specific Registers (MSRs). It is a character device with 1363 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1364 MSR accesses are directed to a specific CPU on multi-processor 1365 systems. 1366 1367config X86_CPUID 1368 tristate "/dev/cpu/*/cpuid - CPU information support" 1369 help 1370 This device gives processes access to the x86 CPUID instruction to 1371 be executed on a specific processor. It is a character device 1372 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1373 /dev/cpu/31/cpuid. 1374 1375choice 1376 prompt "High Memory Support" 1377 default HIGHMEM4G 1378 depends on X86_32 1379 1380config NOHIGHMEM 1381 bool "off" 1382 help 1383 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1384 However, the address space of 32-bit x86 processors is only 4 1385 Gigabytes large. That means that, if you have a large amount of 1386 physical memory, not all of it can be "permanently mapped" by the 1387 kernel. The physical memory that's not permanently mapped is called 1388 "high memory". 1389 1390 If you are compiling a kernel which will never run on a machine with 1391 more than 1 Gigabyte total physical RAM, answer "off" here (default 1392 choice and suitable for most users). This will result in a "3GB/1GB" 1393 split: 3GB are mapped so that each process sees a 3GB virtual memory 1394 space and the remaining part of the 4GB virtual memory space is used 1395 by the kernel to permanently map as much physical memory as 1396 possible. 1397 1398 If the machine has between 1 and 4 Gigabytes physical RAM, then 1399 answer "4GB" here. 1400 1401 If more than 4 Gigabytes is used then answer "64GB" here. This 1402 selection turns Intel PAE (Physical Address Extension) mode on. 1403 PAE implements 3-level paging on IA32 processors. PAE is fully 1404 supported by Linux, PAE mode is implemented on all recent Intel 1405 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1406 then the kernel will not boot on CPUs that don't support PAE! 1407 1408 The actual amount of total physical memory will either be 1409 auto detected or can be forced by using a kernel command line option 1410 such as "mem=256M". (Try "man bootparam" or see the documentation of 1411 your boot loader (lilo or loadlin) about how to pass options to the 1412 kernel at boot time.) 1413 1414 If unsure, say "off". 1415 1416config HIGHMEM4G 1417 bool "4GB" 1418 help 1419 Select this if you have a 32-bit processor and between 1 and 4 1420 gigabytes of physical RAM. 1421 1422config HIGHMEM64G 1423 bool "64GB" 1424 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1425 select X86_PAE 1426 help 1427 Select this if you have a 32-bit processor and more than 4 1428 gigabytes of physical RAM. 1429 1430endchoice 1431 1432choice 1433 prompt "Memory split" if EXPERT 1434 default VMSPLIT_3G 1435 depends on X86_32 1436 help 1437 Select the desired split between kernel and user memory. 1438 1439 If the address range available to the kernel is less than the 1440 physical memory installed, the remaining memory will be available 1441 as "high memory". Accessing high memory is a little more costly 1442 than low memory, as it needs to be mapped into the kernel first. 1443 Note that increasing the kernel address space limits the range 1444 available to user programs, making the address space there 1445 tighter. Selecting anything other than the default 3G/1G split 1446 will also likely make your kernel incompatible with binary-only 1447 kernel modules. 1448 1449 If you are not absolutely sure what you are doing, leave this 1450 option alone! 1451 1452 config VMSPLIT_3G 1453 bool "3G/1G user/kernel split" 1454 config VMSPLIT_3G_OPT 1455 depends on !X86_PAE 1456 bool "3G/1G user/kernel split (for full 1G low memory)" 1457 config VMSPLIT_2G 1458 bool "2G/2G user/kernel split" 1459 config VMSPLIT_2G_OPT 1460 depends on !X86_PAE 1461 bool "2G/2G user/kernel split (for full 2G low memory)" 1462 config VMSPLIT_1G 1463 bool "1G/3G user/kernel split" 1464endchoice 1465 1466config PAGE_OFFSET 1467 hex 1468 default 0xB0000000 if VMSPLIT_3G_OPT 1469 default 0x80000000 if VMSPLIT_2G 1470 default 0x78000000 if VMSPLIT_2G_OPT 1471 default 0x40000000 if VMSPLIT_1G 1472 default 0xC0000000 1473 depends on X86_32 1474 1475config HIGHMEM 1476 def_bool y 1477 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1478 1479config X86_PAE 1480 bool "PAE (Physical Address Extension) Support" 1481 depends on X86_32 && !HIGHMEM4G 1482 select PHYS_ADDR_T_64BIT 1483 select SWIOTLB 1484 help 1485 PAE is required for NX support, and furthermore enables 1486 larger swapspace support for non-overcommit purposes. It 1487 has the cost of more pagetable lookup overhead, and also 1488 consumes more pagetable space per process. 1489 1490config X86_5LEVEL 1491 bool "Enable 5-level page tables support" 1492 default y 1493 select DYNAMIC_MEMORY_LAYOUT 1494 select SPARSEMEM_VMEMMAP 1495 depends on X86_64 1496 help 1497 5-level paging enables access to larger address space: 1498 upto 128 PiB of virtual address space and 4 PiB of 1499 physical address space. 1500 1501 It will be supported by future Intel CPUs. 1502 1503 A kernel with the option enabled can be booted on machines that 1504 support 4- or 5-level paging. 1505 1506 See Documentation/x86/x86_64/5level-paging.rst for more 1507 information. 1508 1509 Say N if unsure. 1510 1511config X86_DIRECT_GBPAGES 1512 def_bool y 1513 depends on X86_64 1514 help 1515 Certain kernel features effectively disable kernel 1516 linear 1 GB mappings (even if the CPU otherwise 1517 supports them), so don't confuse the user by printing 1518 that we have them enabled. 1519 1520config X86_CPA_STATISTICS 1521 bool "Enable statistic for Change Page Attribute" 1522 depends on DEBUG_FS 1523 help 1524 Expose statistics about the Change Page Attribute mechanism, which 1525 helps to determine the effectiveness of preserving large and huge 1526 page mappings when mapping protections are changed. 1527 1528config X86_MEM_ENCRYPT 1529 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1530 select DYNAMIC_PHYSICAL_MASK 1531 def_bool n 1532 1533config AMD_MEM_ENCRYPT 1534 bool "AMD Secure Memory Encryption (SME) support" 1535 depends on X86_64 && CPU_SUP_AMD 1536 select DMA_COHERENT_POOL 1537 select ARCH_USE_MEMREMAP_PROT 1538 select INSTRUCTION_DECODER 1539 select ARCH_HAS_CC_PLATFORM 1540 select X86_MEM_ENCRYPT 1541 help 1542 Say yes to enable support for the encryption of system memory. 1543 This requires an AMD processor that supports Secure Memory 1544 Encryption (SME). 1545 1546config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1547 bool "Activate AMD Secure Memory Encryption (SME) by default" 1548 depends on AMD_MEM_ENCRYPT 1549 help 1550 Say yes to have system memory encrypted by default if running on 1551 an AMD processor that supports Secure Memory Encryption (SME). 1552 1553 If set to Y, then the encryption of system memory can be 1554 deactivated with the mem_encrypt=off command line option. 1555 1556 If set to N, then the encryption of system memory can be 1557 activated with the mem_encrypt=on command line option. 1558 1559# Common NUMA Features 1560config NUMA 1561 bool "NUMA Memory Allocation and Scheduler Support" 1562 depends on SMP 1563 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1564 default y if X86_BIGSMP 1565 select USE_PERCPU_NUMA_NODE_ID 1566 help 1567 Enable NUMA (Non-Uniform Memory Access) support. 1568 1569 The kernel will try to allocate memory used by a CPU on the 1570 local memory controller of the CPU and add some more 1571 NUMA awareness to the kernel. 1572 1573 For 64-bit this is recommended if the system is Intel Core i7 1574 (or later), AMD Opteron, or EM64T NUMA. 1575 1576 For 32-bit this is only needed if you boot a 32-bit 1577 kernel on a 64-bit NUMA platform. 1578 1579 Otherwise, you should say N. 1580 1581config AMD_NUMA 1582 def_bool y 1583 prompt "Old style AMD Opteron NUMA detection" 1584 depends on X86_64 && NUMA && PCI 1585 help 1586 Enable AMD NUMA node topology detection. You should say Y here if 1587 you have a multi processor AMD system. This uses an old method to 1588 read the NUMA configuration directly from the builtin Northbridge 1589 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1590 which also takes priority if both are compiled in. 1591 1592config X86_64_ACPI_NUMA 1593 def_bool y 1594 prompt "ACPI NUMA detection" 1595 depends on X86_64 && NUMA && ACPI && PCI 1596 select ACPI_NUMA 1597 help 1598 Enable ACPI SRAT based node topology detection. 1599 1600config NUMA_EMU 1601 bool "NUMA emulation" 1602 depends on NUMA 1603 help 1604 Enable NUMA emulation. A flat machine will be split 1605 into virtual nodes when booted with "numa=fake=N", where N is the 1606 number of nodes. This is only useful for debugging. 1607 1608config NODES_SHIFT 1609 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1610 range 1 10 1611 default "10" if MAXSMP 1612 default "6" if X86_64 1613 default "3" 1614 depends on NUMA 1615 help 1616 Specify the maximum number of NUMA Nodes available on the target 1617 system. Increases memory reserved to accommodate various tables. 1618 1619config ARCH_FLATMEM_ENABLE 1620 def_bool y 1621 depends on X86_32 && !NUMA 1622 1623config ARCH_SPARSEMEM_ENABLE 1624 def_bool y 1625 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1626 select SPARSEMEM_STATIC if X86_32 1627 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1628 1629config ARCH_SPARSEMEM_DEFAULT 1630 def_bool X86_64 || (NUMA && X86_32) 1631 1632config ARCH_SELECT_MEMORY_MODEL 1633 def_bool y 1634 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1635 1636config ARCH_MEMORY_PROBE 1637 bool "Enable sysfs memory/probe interface" 1638 depends on MEMORY_HOTPLUG 1639 help 1640 This option enables a sysfs memory/probe interface for testing. 1641 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1642 If you are unsure how to answer this question, answer N. 1643 1644config ARCH_PROC_KCORE_TEXT 1645 def_bool y 1646 depends on X86_64 && PROC_KCORE 1647 1648config ILLEGAL_POINTER_VALUE 1649 hex 1650 default 0 if X86_32 1651 default 0xdead000000000000 if X86_64 1652 1653config X86_PMEM_LEGACY_DEVICE 1654 bool 1655 1656config X86_PMEM_LEGACY 1657 tristate "Support non-standard NVDIMMs and ADR protected memory" 1658 depends on PHYS_ADDR_T_64BIT 1659 depends on BLK_DEV 1660 select X86_PMEM_LEGACY_DEVICE 1661 select NUMA_KEEP_MEMINFO if NUMA 1662 select LIBNVDIMM 1663 help 1664 Treat memory marked using the non-standard e820 type of 12 as used 1665 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1666 The kernel will offer these regions to the 'pmem' driver so 1667 they can be used for persistent storage. 1668 1669 Say Y if unsure. 1670 1671config HIGHPTE 1672 bool "Allocate 3rd-level pagetables from highmem" 1673 depends on HIGHMEM 1674 help 1675 The VM uses one page table entry for each page of physical memory. 1676 For systems with a lot of RAM, this can be wasteful of precious 1677 low memory. Setting this option will put user-space page table 1678 entries in high memory. 1679 1680config X86_CHECK_BIOS_CORRUPTION 1681 bool "Check for low memory corruption" 1682 help 1683 Periodically check for memory corruption in low memory, which 1684 is suspected to be caused by BIOS. Even when enabled in the 1685 configuration, it is disabled at runtime. Enable it by 1686 setting "memory_corruption_check=1" on the kernel command 1687 line. By default it scans the low 64k of memory every 60 1688 seconds; see the memory_corruption_check_size and 1689 memory_corruption_check_period parameters in 1690 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1691 1692 When enabled with the default parameters, this option has 1693 almost no overhead, as it reserves a relatively small amount 1694 of memory and scans it infrequently. It both detects corruption 1695 and prevents it from affecting the running system. 1696 1697 It is, however, intended as a diagnostic tool; if repeatable 1698 BIOS-originated corruption always affects the same memory, 1699 you can use memmap= to prevent the kernel from using that 1700 memory. 1701 1702config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1703 bool "Set the default setting of memory_corruption_check" 1704 depends on X86_CHECK_BIOS_CORRUPTION 1705 default y 1706 help 1707 Set whether the default state of memory_corruption_check is 1708 on or off. 1709 1710config MATH_EMULATION 1711 bool 1712 depends on MODIFY_LDT_SYSCALL 1713 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1714 help 1715 Linux can emulate a math coprocessor (used for floating point 1716 operations) if you don't have one. 486DX and Pentium processors have 1717 a math coprocessor built in, 486SX and 386 do not, unless you added 1718 a 487DX or 387, respectively. (The messages during boot time can 1719 give you some hints here ["man dmesg"].) Everyone needs either a 1720 coprocessor or this emulation. 1721 1722 If you don't have a math coprocessor, you need to say Y here; if you 1723 say Y here even though you have a coprocessor, the coprocessor will 1724 be used nevertheless. (This behavior can be changed with the kernel 1725 command line option "no387", which comes handy if your coprocessor 1726 is broken. Try "man bootparam" or see the documentation of your boot 1727 loader (lilo or loadlin) about how to pass options to the kernel at 1728 boot time.) This means that it is a good idea to say Y here if you 1729 intend to use this kernel on different machines. 1730 1731 More information about the internals of the Linux math coprocessor 1732 emulation can be found in <file:arch/x86/math-emu/README>. 1733 1734 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1735 kernel, it won't hurt. 1736 1737config MTRR 1738 def_bool y 1739 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1740 help 1741 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1742 the Memory Type Range Registers (MTRRs) may be used to control 1743 processor access to memory ranges. This is most useful if you have 1744 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1745 allows bus write transfers to be combined into a larger transfer 1746 before bursting over the PCI/AGP bus. This can increase performance 1747 of image write operations 2.5 times or more. Saying Y here creates a 1748 /proc/mtrr file which may be used to manipulate your processor's 1749 MTRRs. Typically the X server should use this. 1750 1751 This code has a reasonably generic interface so that similar 1752 control registers on other processors can be easily supported 1753 as well: 1754 1755 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1756 Registers (ARRs) which provide a similar functionality to MTRRs. For 1757 these, the ARRs are used to emulate the MTRRs. 1758 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1759 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1760 write-combining. All of these processors are supported by this code 1761 and it makes sense to say Y here if you have one of them. 1762 1763 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1764 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1765 can lead to all sorts of problems, so it's good to say Y here. 1766 1767 You can safely say Y even if your machine doesn't have MTRRs, you'll 1768 just add about 9 KB to your kernel. 1769 1770 See <file:Documentation/x86/mtrr.rst> for more information. 1771 1772config MTRR_SANITIZER 1773 def_bool y 1774 prompt "MTRR cleanup support" 1775 depends on MTRR 1776 help 1777 Convert MTRR layout from continuous to discrete, so X drivers can 1778 add writeback entries. 1779 1780 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1781 The largest mtrr entry size for a continuous block can be set with 1782 mtrr_chunk_size. 1783 1784 If unsure, say Y. 1785 1786config MTRR_SANITIZER_ENABLE_DEFAULT 1787 int "MTRR cleanup enable value (0-1)" 1788 range 0 1 1789 default "0" 1790 depends on MTRR_SANITIZER 1791 help 1792 Enable mtrr cleanup default value 1793 1794config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1795 int "MTRR cleanup spare reg num (0-7)" 1796 range 0 7 1797 default "1" 1798 depends on MTRR_SANITIZER 1799 help 1800 mtrr cleanup spare entries default, it can be changed via 1801 mtrr_spare_reg_nr=N on the kernel command line. 1802 1803config X86_PAT 1804 def_bool y 1805 prompt "x86 PAT support" if EXPERT 1806 depends on MTRR 1807 help 1808 Use PAT attributes to setup page level cache control. 1809 1810 PATs are the modern equivalents of MTRRs and are much more 1811 flexible than MTRRs. 1812 1813 Say N here if you see bootup problems (boot crash, boot hang, 1814 spontaneous reboots) or a non-working video driver. 1815 1816 If unsure, say Y. 1817 1818config ARCH_USES_PG_UNCACHED 1819 def_bool y 1820 depends on X86_PAT 1821 1822config X86_UMIP 1823 def_bool y 1824 prompt "User Mode Instruction Prevention" if EXPERT 1825 help 1826 User Mode Instruction Prevention (UMIP) is a security feature in 1827 some x86 processors. If enabled, a general protection fault is 1828 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1829 executed in user mode. These instructions unnecessarily expose 1830 information about the hardware state. 1831 1832 The vast majority of applications do not use these instructions. 1833 For the very few that do, software emulation is provided in 1834 specific cases in protected and virtual-8086 modes. Emulated 1835 results are dummy. 1836 1837config CC_HAS_IBT 1838 # GCC >= 9 and binutils >= 2.29 1839 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1840 # Clang/LLVM >= 14 1841 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1842 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1843 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1844 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1845 $(as-instr,endbr64) 1846 1847config X86_KERNEL_IBT 1848 prompt "Indirect Branch Tracking" 1849 bool 1850 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1851 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1852 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1853 select OBJTOOL 1854 help 1855 Build the kernel with support for Indirect Branch Tracking, a 1856 hardware support course-grain forward-edge Control Flow Integrity 1857 protection. It enforces that all indirect calls must land on 1858 an ENDBR instruction, as such, the compiler will instrument the 1859 code with them to make this happen. 1860 1861 In addition to building the kernel with IBT, seal all functions that 1862 are not indirect call targets, avoiding them ever becoming one. 1863 1864 This requires LTO like objtool runs and will slow down the build. It 1865 does significantly reduce the number of ENDBR instructions in the 1866 kernel image. 1867 1868config X86_INTEL_MEMORY_PROTECTION_KEYS 1869 prompt "Memory Protection Keys" 1870 def_bool y 1871 # Note: only available in 64-bit mode 1872 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1873 select ARCH_USES_HIGH_VMA_FLAGS 1874 select ARCH_HAS_PKEYS 1875 help 1876 Memory Protection Keys provides a mechanism for enforcing 1877 page-based protections, but without requiring modification of the 1878 page tables when an application changes protection domains. 1879 1880 For details, see Documentation/core-api/protection-keys.rst 1881 1882 If unsure, say y. 1883 1884choice 1885 prompt "TSX enable mode" 1886 depends on CPU_SUP_INTEL 1887 default X86_INTEL_TSX_MODE_OFF 1888 help 1889 Intel's TSX (Transactional Synchronization Extensions) feature 1890 allows to optimize locking protocols through lock elision which 1891 can lead to a noticeable performance boost. 1892 1893 On the other hand it has been shown that TSX can be exploited 1894 to form side channel attacks (e.g. TAA) and chances are there 1895 will be more of those attacks discovered in the future. 1896 1897 Therefore TSX is not enabled by default (aka tsx=off). An admin 1898 might override this decision by tsx=on the command line parameter. 1899 Even with TSX enabled, the kernel will attempt to enable the best 1900 possible TAA mitigation setting depending on the microcode available 1901 for the particular machine. 1902 1903 This option allows to set the default tsx mode between tsx=on, =off 1904 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1905 details. 1906 1907 Say off if not sure, auto if TSX is in use but it should be used on safe 1908 platforms or on if TSX is in use and the security aspect of tsx is not 1909 relevant. 1910 1911config X86_INTEL_TSX_MODE_OFF 1912 bool "off" 1913 help 1914 TSX is disabled if possible - equals to tsx=off command line parameter. 1915 1916config X86_INTEL_TSX_MODE_ON 1917 bool "on" 1918 help 1919 TSX is always enabled on TSX capable HW - equals the tsx=on command 1920 line parameter. 1921 1922config X86_INTEL_TSX_MODE_AUTO 1923 bool "auto" 1924 help 1925 TSX is enabled on TSX capable HW that is believed to be safe against 1926 side channel attacks- equals the tsx=auto command line parameter. 1927endchoice 1928 1929config X86_SGX 1930 bool "Software Guard eXtensions (SGX)" 1931 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1932 depends on CRYPTO=y 1933 depends on CRYPTO_SHA256=y 1934 select SRCU 1935 select MMU_NOTIFIER 1936 select NUMA_KEEP_MEMINFO if NUMA 1937 select XARRAY_MULTI 1938 help 1939 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1940 that can be used by applications to set aside private regions of code 1941 and data, referred to as enclaves. An enclave's private memory can 1942 only be accessed by code running within the enclave. Accesses from 1943 outside the enclave, including other enclaves, are disallowed by 1944 hardware. 1945 1946 If unsure, say N. 1947 1948config EFI 1949 bool "EFI runtime service support" 1950 depends on ACPI 1951 select UCS2_STRING 1952 select EFI_RUNTIME_WRAPPERS 1953 select ARCH_USE_MEMREMAP_PROT 1954 help 1955 This enables the kernel to use EFI runtime services that are 1956 available (such as the EFI variable services). 1957 1958 This option is only useful on systems that have EFI firmware. 1959 In addition, you should use the latest ELILO loader available 1960 at <http://elilo.sourceforge.net> in order to take advantage 1961 of EFI runtime services. However, even with this option, the 1962 resultant kernel should continue to boot on existing non-EFI 1963 platforms. 1964 1965config EFI_STUB 1966 bool "EFI stub support" 1967 depends on EFI 1968 depends on $(cc-option,-mabi=ms) || X86_32 1969 select RELOCATABLE 1970 help 1971 This kernel feature allows a bzImage to be loaded directly 1972 by EFI firmware without the use of a bootloader. 1973 1974 See Documentation/admin-guide/efi-stub.rst for more information. 1975 1976config EFI_MIXED 1977 bool "EFI mixed-mode support" 1978 depends on EFI_STUB && X86_64 1979 help 1980 Enabling this feature allows a 64-bit kernel to be booted 1981 on a 32-bit firmware, provided that your CPU supports 64-bit 1982 mode. 1983 1984 Note that it is not possible to boot a mixed-mode enabled 1985 kernel via the EFI boot stub - a bootloader that supports 1986 the EFI handover protocol must be used. 1987 1988 If unsure, say N. 1989 1990source "kernel/Kconfig.hz" 1991 1992config KEXEC 1993 bool "kexec system call" 1994 select KEXEC_CORE 1995 help 1996 kexec is a system call that implements the ability to shutdown your 1997 current kernel, and to start another kernel. It is like a reboot 1998 but it is independent of the system firmware. And like a reboot 1999 you can start any kernel with it, not just Linux. 2000 2001 The name comes from the similarity to the exec system call. 2002 2003 It is an ongoing process to be certain the hardware in a machine 2004 is properly shutdown, so do not be surprised if this code does not 2005 initially work for you. As of this writing the exact hardware 2006 interface is strongly in flux, so no good recommendation can be 2007 made. 2008 2009config KEXEC_FILE 2010 bool "kexec file based system call" 2011 select KEXEC_CORE 2012 select HAVE_IMA_KEXEC if IMA 2013 depends on X86_64 2014 depends on CRYPTO=y 2015 depends on CRYPTO_SHA256=y 2016 help 2017 This is new version of kexec system call. This system call is 2018 file based and takes file descriptors as system call argument 2019 for kernel and initramfs as opposed to list of segments as 2020 accepted by previous system call. 2021 2022config ARCH_HAS_KEXEC_PURGATORY 2023 def_bool KEXEC_FILE 2024 2025config KEXEC_SIG 2026 bool "Verify kernel signature during kexec_file_load() syscall" 2027 depends on KEXEC_FILE 2028 help 2029 2030 This option makes the kexec_file_load() syscall check for a valid 2031 signature of the kernel image. The image can still be loaded without 2032 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2033 there's a signature that we can check, then it must be valid. 2034 2035 In addition to this option, you need to enable signature 2036 verification for the corresponding kernel image type being 2037 loaded in order for this to work. 2038 2039config KEXEC_SIG_FORCE 2040 bool "Require a valid signature in kexec_file_load() syscall" 2041 depends on KEXEC_SIG 2042 help 2043 This option makes kernel signature verification mandatory for 2044 the kexec_file_load() syscall. 2045 2046config KEXEC_BZIMAGE_VERIFY_SIG 2047 bool "Enable bzImage signature verification support" 2048 depends on KEXEC_SIG 2049 depends on SIGNED_PE_FILE_VERIFICATION 2050 select SYSTEM_TRUSTED_KEYRING 2051 help 2052 Enable bzImage signature verification support. 2053 2054config CRASH_DUMP 2055 bool "kernel crash dumps" 2056 depends on X86_64 || (X86_32 && HIGHMEM) 2057 help 2058 Generate crash dump after being started by kexec. 2059 This should be normally only set in special crash dump kernels 2060 which are loaded in the main kernel with kexec-tools into 2061 a specially reserved region and then later executed after 2062 a crash by kdump/kexec. The crash dump kernel must be compiled 2063 to a memory address not used by the main kernel or BIOS using 2064 PHYSICAL_START, or it must be built as a relocatable image 2065 (CONFIG_RELOCATABLE=y). 2066 For more details see Documentation/admin-guide/kdump/kdump.rst 2067 2068config KEXEC_JUMP 2069 bool "kexec jump" 2070 depends on KEXEC && HIBERNATION 2071 help 2072 Jump between original kernel and kexeced kernel and invoke 2073 code in physical address mode via KEXEC 2074 2075config PHYSICAL_START 2076 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2077 default "0x1000000" 2078 help 2079 This gives the physical address where the kernel is loaded. 2080 2081 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2082 bzImage will decompress itself to above physical address and 2083 run from there. Otherwise, bzImage will run from the address where 2084 it has been loaded by the boot loader and will ignore above physical 2085 address. 2086 2087 In normal kdump cases one does not have to set/change this option 2088 as now bzImage can be compiled as a completely relocatable image 2089 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2090 address. This option is mainly useful for the folks who don't want 2091 to use a bzImage for capturing the crash dump and want to use a 2092 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2093 to be specifically compiled to run from a specific memory area 2094 (normally a reserved region) and this option comes handy. 2095 2096 So if you are using bzImage for capturing the crash dump, 2097 leave the value here unchanged to 0x1000000 and set 2098 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2099 for capturing the crash dump change this value to start of 2100 the reserved region. In other words, it can be set based on 2101 the "X" value as specified in the "crashkernel=YM@XM" 2102 command line boot parameter passed to the panic-ed 2103 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2104 for more details about crash dumps. 2105 2106 Usage of bzImage for capturing the crash dump is recommended as 2107 one does not have to build two kernels. Same kernel can be used 2108 as production kernel and capture kernel. Above option should have 2109 gone away after relocatable bzImage support is introduced. But it 2110 is present because there are users out there who continue to use 2111 vmlinux for dump capture. This option should go away down the 2112 line. 2113 2114 Don't change this unless you know what you are doing. 2115 2116config RELOCATABLE 2117 bool "Build a relocatable kernel" 2118 default y 2119 help 2120 This builds a kernel image that retains relocation information 2121 so it can be loaded someplace besides the default 1MB. 2122 The relocations tend to make the kernel binary about 10% larger, 2123 but are discarded at runtime. 2124 2125 One use is for the kexec on panic case where the recovery kernel 2126 must live at a different physical address than the primary 2127 kernel. 2128 2129 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2130 it has been loaded at and the compile time physical address 2131 (CONFIG_PHYSICAL_START) is used as the minimum location. 2132 2133config RANDOMIZE_BASE 2134 bool "Randomize the address of the kernel image (KASLR)" 2135 depends on RELOCATABLE 2136 default y 2137 help 2138 In support of Kernel Address Space Layout Randomization (KASLR), 2139 this randomizes the physical address at which the kernel image 2140 is decompressed and the virtual address where the kernel 2141 image is mapped, as a security feature that deters exploit 2142 attempts relying on knowledge of the location of kernel 2143 code internals. 2144 2145 On 64-bit, the kernel physical and virtual addresses are 2146 randomized separately. The physical address will be anywhere 2147 between 16MB and the top of physical memory (up to 64TB). The 2148 virtual address will be randomized from 16MB up to 1GB (9 bits 2149 of entropy). Note that this also reduces the memory space 2150 available to kernel modules from 1.5GB to 1GB. 2151 2152 On 32-bit, the kernel physical and virtual addresses are 2153 randomized together. They will be randomized from 16MB up to 2154 512MB (8 bits of entropy). 2155 2156 Entropy is generated using the RDRAND instruction if it is 2157 supported. If RDTSC is supported, its value is mixed into 2158 the entropy pool as well. If neither RDRAND nor RDTSC are 2159 supported, then entropy is read from the i8254 timer. The 2160 usable entropy is limited by the kernel being built using 2161 2GB addressing, and that PHYSICAL_ALIGN must be at a 2162 minimum of 2MB. As a result, only 10 bits of entropy are 2163 theoretically possible, but the implementations are further 2164 limited due to memory layouts. 2165 2166 If unsure, say Y. 2167 2168# Relocation on x86 needs some additional build support 2169config X86_NEED_RELOCS 2170 def_bool y 2171 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2172 2173config PHYSICAL_ALIGN 2174 hex "Alignment value to which kernel should be aligned" 2175 default "0x200000" 2176 range 0x2000 0x1000000 if X86_32 2177 range 0x200000 0x1000000 if X86_64 2178 help 2179 This value puts the alignment restrictions on physical address 2180 where kernel is loaded and run from. Kernel is compiled for an 2181 address which meets above alignment restriction. 2182 2183 If bootloader loads the kernel at a non-aligned address and 2184 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2185 address aligned to above value and run from there. 2186 2187 If bootloader loads the kernel at a non-aligned address and 2188 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2189 load address and decompress itself to the address it has been 2190 compiled for and run from there. The address for which kernel is 2191 compiled already meets above alignment restrictions. Hence the 2192 end result is that kernel runs from a physical address meeting 2193 above alignment restrictions. 2194 2195 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2196 this value must be a multiple of 0x200000. 2197 2198 Don't change this unless you know what you are doing. 2199 2200config DYNAMIC_MEMORY_LAYOUT 2201 bool 2202 help 2203 This option makes base addresses of vmalloc and vmemmap as well as 2204 __PAGE_OFFSET movable during boot. 2205 2206config RANDOMIZE_MEMORY 2207 bool "Randomize the kernel memory sections" 2208 depends on X86_64 2209 depends on RANDOMIZE_BASE 2210 select DYNAMIC_MEMORY_LAYOUT 2211 default RANDOMIZE_BASE 2212 help 2213 Randomizes the base virtual address of kernel memory sections 2214 (physical memory mapping, vmalloc & vmemmap). This security feature 2215 makes exploits relying on predictable memory locations less reliable. 2216 2217 The order of allocations remains unchanged. Entropy is generated in 2218 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2219 configuration have in average 30,000 different possible virtual 2220 addresses for each memory section. 2221 2222 If unsure, say Y. 2223 2224config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2225 hex "Physical memory mapping padding" if EXPERT 2226 depends on RANDOMIZE_MEMORY 2227 default "0xa" if MEMORY_HOTPLUG 2228 default "0x0" 2229 range 0x1 0x40 if MEMORY_HOTPLUG 2230 range 0x0 0x40 2231 help 2232 Define the padding in terabytes added to the existing physical 2233 memory size during kernel memory randomization. It is useful 2234 for memory hotplug support but reduces the entropy available for 2235 address randomization. 2236 2237 If unsure, leave at the default value. 2238 2239config HOTPLUG_CPU 2240 def_bool y 2241 depends on SMP 2242 2243config BOOTPARAM_HOTPLUG_CPU0 2244 bool "Set default setting of cpu0_hotpluggable" 2245 depends on HOTPLUG_CPU 2246 help 2247 Set whether default state of cpu0_hotpluggable is on or off. 2248 2249 Say Y here to enable CPU0 hotplug by default. If this switch 2250 is turned on, there is no need to give cpu0_hotplug kernel 2251 parameter and the CPU0 hotplug feature is enabled by default. 2252 2253 Please note: there are two known CPU0 dependencies if you want 2254 to enable the CPU0 hotplug feature either by this switch or by 2255 cpu0_hotplug kernel parameter. 2256 2257 First, resume from hibernate or suspend always starts from CPU0. 2258 So hibernate and suspend are prevented if CPU0 is offline. 2259 2260 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2261 offline if any interrupt can not migrate out of CPU0. There may 2262 be other CPU0 dependencies. 2263 2264 Please make sure the dependencies are under your control before 2265 you enable this feature. 2266 2267 Say N if you don't want to enable CPU0 hotplug feature by default. 2268 You still can enable the CPU0 hotplug feature at boot by kernel 2269 parameter cpu0_hotplug. 2270 2271config DEBUG_HOTPLUG_CPU0 2272 def_bool n 2273 prompt "Debug CPU0 hotplug" 2274 depends on HOTPLUG_CPU 2275 help 2276 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2277 soon as possible and boots up userspace with CPU0 offlined. User 2278 can online CPU0 back after boot time. 2279 2280 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2281 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2282 compilation or giving cpu0_hotplug kernel parameter at boot. 2283 2284 If unsure, say N. 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_SLS 2434 def_bool $(cc-option,-mharden-sls=all) 2435 2436config CC_HAS_RETURN_THUNK 2437 def_bool $(cc-option,-mfunction-return=thunk-extern) 2438 2439menuconfig SPECULATION_MITIGATIONS 2440 bool "Mitigations for speculative execution vulnerabilities" 2441 default y 2442 help 2443 Say Y here to enable options which enable mitigations for 2444 speculative execution hardware vulnerabilities. 2445 2446 If you say N, all mitigations will be disabled. You really 2447 should know what you are doing to say so. 2448 2449if SPECULATION_MITIGATIONS 2450 2451config PAGE_TABLE_ISOLATION 2452 bool "Remove the kernel mapping in user mode" 2453 default y 2454 depends on (X86_64 || X86_PAE) 2455 help 2456 This feature reduces the number of hardware side channels by 2457 ensuring that the majority of kernel addresses are not mapped 2458 into userspace. 2459 2460 See Documentation/x86/pti.rst for more details. 2461 2462config RETPOLINE 2463 bool "Avoid speculative indirect branches in kernel" 2464 select OBJTOOL if HAVE_OBJTOOL 2465 default y 2466 help 2467 Compile kernel with the retpoline compiler options to guard against 2468 kernel-to-user data leaks by avoiding speculative indirect 2469 branches. Requires a compiler with -mindirect-branch=thunk-extern 2470 support for full protection. The kernel may run slower. 2471 2472config RETHUNK 2473 bool "Enable return-thunks" 2474 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2475 select OBJTOOL if HAVE_OBJTOOL 2476 default y if X86_64 2477 help 2478 Compile the kernel with the return-thunks compiler option to guard 2479 against kernel-to-user data leaks by avoiding return speculation. 2480 Requires a compiler with -mfunction-return=thunk-extern 2481 support for full protection. The kernel may run slower. 2482 2483config CPU_UNRET_ENTRY 2484 bool "Enable UNRET on kernel entry" 2485 depends on CPU_SUP_AMD && RETHUNK && X86_64 2486 default y 2487 help 2488 Compile the kernel with support for the retbleed=unret mitigation. 2489 2490config CPU_IBPB_ENTRY 2491 bool "Enable IBPB on kernel entry" 2492 depends on CPU_SUP_AMD && X86_64 2493 default y 2494 help 2495 Compile the kernel with support for the retbleed=ibpb mitigation. 2496 2497config CPU_IBRS_ENTRY 2498 bool "Enable IBRS on kernel entry" 2499 depends on CPU_SUP_INTEL && X86_64 2500 default y 2501 help 2502 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2503 This mitigates both spectre_v2 and retbleed at great cost to 2504 performance. 2505 2506config SLS 2507 bool "Mitigate Straight-Line-Speculation" 2508 depends on CC_HAS_SLS && X86_64 2509 select OBJTOOL if HAVE_OBJTOOL 2510 default n 2511 help 2512 Compile the kernel with straight-line-speculation options to guard 2513 against straight line speculation. The kernel image might be slightly 2514 larger. 2515 2516endif 2517 2518config ARCH_HAS_ADD_PAGES 2519 def_bool y 2520 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2521 2522config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2523 def_bool y 2524 2525menu "Power management and ACPI options" 2526 2527config ARCH_HIBERNATION_HEADER 2528 def_bool y 2529 depends on HIBERNATION 2530 2531source "kernel/power/Kconfig" 2532 2533source "drivers/acpi/Kconfig" 2534 2535config X86_APM_BOOT 2536 def_bool y 2537 depends on APM 2538 2539menuconfig APM 2540 tristate "APM (Advanced Power Management) BIOS support" 2541 depends on X86_32 && PM_SLEEP 2542 help 2543 APM is a BIOS specification for saving power using several different 2544 techniques. This is mostly useful for battery powered laptops with 2545 APM compliant BIOSes. If you say Y here, the system time will be 2546 reset after a RESUME operation, the /proc/apm device will provide 2547 battery status information, and user-space programs will receive 2548 notification of APM "events" (e.g. battery status change). 2549 2550 If you select "Y" here, you can disable actual use of the APM 2551 BIOS by passing the "apm=off" option to the kernel at boot time. 2552 2553 Note that the APM support is almost completely disabled for 2554 machines with more than one CPU. 2555 2556 In order to use APM, you will need supporting software. For location 2557 and more information, read <file:Documentation/power/apm-acpi.rst> 2558 and the Battery Powered Linux mini-HOWTO, available from 2559 <http://www.tldp.org/docs.html#howto>. 2560 2561 This driver does not spin down disk drives (see the hdparm(8) 2562 manpage ("man 8 hdparm") for that), and it doesn't turn off 2563 VESA-compliant "green" monitors. 2564 2565 This driver does not support the TI 4000M TravelMate and the ACER 2566 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2567 desktop machines also don't have compliant BIOSes, and this driver 2568 may cause those machines to panic during the boot phase. 2569 2570 Generally, if you don't have a battery in your machine, there isn't 2571 much point in using this driver and you should say N. If you get 2572 random kernel OOPSes or reboots that don't seem to be related to 2573 anything, try disabling/enabling this option (or disabling/enabling 2574 APM in your BIOS). 2575 2576 Some other things you should try when experiencing seemingly random, 2577 "weird" problems: 2578 2579 1) make sure that you have enough swap space and that it is 2580 enabled. 2581 2) pass the "idle=poll" option to the kernel 2582 3) switch on floating point emulation in the kernel and pass 2583 the "no387" option to the kernel 2584 4) pass the "floppy=nodma" option to the kernel 2585 5) pass the "mem=4M" option to the kernel (thereby disabling 2586 all but the first 4 MB of RAM) 2587 6) make sure that the CPU is not over clocked. 2588 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2589 8) disable the cache from your BIOS settings 2590 9) install a fan for the video card or exchange video RAM 2591 10) install a better fan for the CPU 2592 11) exchange RAM chips 2593 12) exchange the motherboard. 2594 2595 To compile this driver as a module, choose M here: the 2596 module will be called apm. 2597 2598if APM 2599 2600config APM_IGNORE_USER_SUSPEND 2601 bool "Ignore USER SUSPEND" 2602 help 2603 This option will ignore USER SUSPEND requests. On machines with a 2604 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2605 series notebooks, it is necessary to say Y because of a BIOS bug. 2606 2607config APM_DO_ENABLE 2608 bool "Enable PM at boot time" 2609 help 2610 Enable APM features at boot time. From page 36 of the APM BIOS 2611 specification: "When disabled, the APM BIOS does not automatically 2612 power manage devices, enter the Standby State, enter the Suspend 2613 State, or take power saving steps in response to CPU Idle calls." 2614 This driver will make CPU Idle calls when Linux is idle (unless this 2615 feature is turned off -- see "Do CPU IDLE calls", below). This 2616 should always save battery power, but more complicated APM features 2617 will be dependent on your BIOS implementation. You may need to turn 2618 this option off if your computer hangs at boot time when using APM 2619 support, or if it beeps continuously instead of suspending. Turn 2620 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2621 T400CDT. This is off by default since most machines do fine without 2622 this feature. 2623 2624config APM_CPU_IDLE 2625 depends on CPU_IDLE 2626 bool "Make CPU Idle calls when idle" 2627 help 2628 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2629 On some machines, this can activate improved power savings, such as 2630 a slowed CPU clock rate, when the machine is idle. These idle calls 2631 are made after the idle loop has run for some length of time (e.g., 2632 333 mS). On some machines, this will cause a hang at boot time or 2633 whenever the CPU becomes idle. (On machines with more than one CPU, 2634 this option does nothing.) 2635 2636config APM_DISPLAY_BLANK 2637 bool "Enable console blanking using APM" 2638 help 2639 Enable console blanking using the APM. Some laptops can use this to 2640 turn off the LCD backlight when the screen blanker of the Linux 2641 virtual console blanks the screen. Note that this is only used by 2642 the virtual console screen blanker, and won't turn off the backlight 2643 when using the X Window system. This also doesn't have anything to 2644 do with your VESA-compliant power-saving monitor. Further, this 2645 option doesn't work for all laptops -- it might not turn off your 2646 backlight at all, or it might print a lot of errors to the console, 2647 especially if you are using gpm. 2648 2649config APM_ALLOW_INTS 2650 bool "Allow interrupts during APM BIOS calls" 2651 help 2652 Normally we disable external interrupts while we are making calls to 2653 the APM BIOS as a measure to lessen the effects of a badly behaving 2654 BIOS implementation. The BIOS should reenable interrupts if it 2655 needs to. Unfortunately, some BIOSes do not -- especially those in 2656 many of the newer IBM Thinkpads. If you experience hangs when you 2657 suspend, try setting this to Y. Otherwise, say N. 2658 2659endif # APM 2660 2661source "drivers/cpufreq/Kconfig" 2662 2663source "drivers/cpuidle/Kconfig" 2664 2665source "drivers/idle/Kconfig" 2666 2667endmenu 2668 2669menu "Bus options (PCI etc.)" 2670 2671choice 2672 prompt "PCI access mode" 2673 depends on X86_32 && PCI 2674 default PCI_GOANY 2675 help 2676 On PCI systems, the BIOS can be used to detect the PCI devices and 2677 determine their configuration. However, some old PCI motherboards 2678 have BIOS bugs and may crash if this is done. Also, some embedded 2679 PCI-based systems don't have any BIOS at all. Linux can also try to 2680 detect the PCI hardware directly without using the BIOS. 2681 2682 With this option, you can specify how Linux should detect the 2683 PCI devices. If you choose "BIOS", the BIOS will be used, 2684 if you choose "Direct", the BIOS won't be used, and if you 2685 choose "MMConfig", then PCI Express MMCONFIG will be used. 2686 If you choose "Any", the kernel will try MMCONFIG, then the 2687 direct access method and falls back to the BIOS if that doesn't 2688 work. If unsure, go with the default, which is "Any". 2689 2690config PCI_GOBIOS 2691 bool "BIOS" 2692 2693config PCI_GOMMCONFIG 2694 bool "MMConfig" 2695 2696config PCI_GODIRECT 2697 bool "Direct" 2698 2699config PCI_GOOLPC 2700 bool "OLPC XO-1" 2701 depends on OLPC 2702 2703config PCI_GOANY 2704 bool "Any" 2705 2706endchoice 2707 2708config PCI_BIOS 2709 def_bool y 2710 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2711 2712# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2713config PCI_DIRECT 2714 def_bool y 2715 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2716 2717config PCI_MMCONFIG 2718 bool "Support mmconfig PCI config space access" if X86_64 2719 default y 2720 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2721 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2722 2723config PCI_OLPC 2724 def_bool y 2725 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2726 2727config PCI_XEN 2728 def_bool y 2729 depends on PCI && XEN 2730 2731config MMCONF_FAM10H 2732 def_bool y 2733 depends on X86_64 && PCI_MMCONFIG && ACPI 2734 2735config PCI_CNB20LE_QUIRK 2736 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2737 depends on PCI 2738 help 2739 Read the PCI windows out of the CNB20LE host bridge. This allows 2740 PCI hotplug to work on systems with the CNB20LE chipset which do 2741 not have ACPI. 2742 2743 There's no public spec for this chipset, and this functionality 2744 is known to be incomplete. 2745 2746 You should say N unless you know you need this. 2747 2748config ISA_BUS 2749 bool "ISA bus support on modern systems" if EXPERT 2750 help 2751 Expose ISA bus device drivers and options available for selection and 2752 configuration. Enable this option if your target machine has an ISA 2753 bus. ISA is an older system, displaced by PCI and newer bus 2754 architectures -- if your target machine is modern, it probably does 2755 not have an ISA bus. 2756 2757 If unsure, say N. 2758 2759# x86_64 have no ISA slots, but can have ISA-style DMA. 2760config ISA_DMA_API 2761 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2762 default y 2763 help 2764 Enables ISA-style DMA support for devices requiring such controllers. 2765 If unsure, say Y. 2766 2767if X86_32 2768 2769config ISA 2770 bool "ISA support" 2771 help 2772 Find out whether you have ISA slots on your motherboard. ISA is the 2773 name of a bus system, i.e. the way the CPU talks to the other stuff 2774 inside your box. Other bus systems are PCI, EISA, MicroChannel 2775 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2776 newer boards don't support it. If you have ISA, say Y, otherwise N. 2777 2778config SCx200 2779 tristate "NatSemi SCx200 support" 2780 help 2781 This provides basic support for National Semiconductor's 2782 (now AMD's) Geode processors. The driver probes for the 2783 PCI-IDs of several on-chip devices, so its a good dependency 2784 for other scx200_* drivers. 2785 2786 If compiled as a module, the driver is named scx200. 2787 2788config SCx200HR_TIMER 2789 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2790 depends on SCx200 2791 default y 2792 help 2793 This driver provides a clocksource built upon the on-chip 2794 27MHz high-resolution timer. Its also a workaround for 2795 NSC Geode SC-1100's buggy TSC, which loses time when the 2796 processor goes idle (as is done by the scheduler). The 2797 other workaround is idle=poll boot option. 2798 2799config OLPC 2800 bool "One Laptop Per Child support" 2801 depends on !X86_PAE 2802 select GPIOLIB 2803 select OF 2804 select OF_PROMTREE 2805 select IRQ_DOMAIN 2806 select OLPC_EC 2807 help 2808 Add support for detecting the unique features of the OLPC 2809 XO hardware. 2810 2811config OLPC_XO1_PM 2812 bool "OLPC XO-1 Power Management" 2813 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2814 help 2815 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2816 2817config OLPC_XO1_RTC 2818 bool "OLPC XO-1 Real Time Clock" 2819 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2820 help 2821 Add support for the XO-1 real time clock, which can be used as a 2822 programmable wakeup source. 2823 2824config OLPC_XO1_SCI 2825 bool "OLPC XO-1 SCI extras" 2826 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2827 depends on INPUT=y 2828 select POWER_SUPPLY 2829 help 2830 Add support for SCI-based features of the OLPC XO-1 laptop: 2831 - EC-driven system wakeups 2832 - Power button 2833 - Ebook switch 2834 - Lid switch 2835 - AC adapter status updates 2836 - Battery status updates 2837 2838config OLPC_XO15_SCI 2839 bool "OLPC XO-1.5 SCI extras" 2840 depends on OLPC && ACPI 2841 select POWER_SUPPLY 2842 help 2843 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2844 - EC-driven system wakeups 2845 - AC adapter status updates 2846 - Battery status updates 2847 2848config ALIX 2849 bool "PCEngines ALIX System Support (LED setup)" 2850 select GPIOLIB 2851 help 2852 This option enables system support for the PCEngines ALIX. 2853 At present this just sets up LEDs for GPIO control on 2854 ALIX2/3/6 boards. However, other system specific setup should 2855 get added here. 2856 2857 Note: You must still enable the drivers for GPIO and LED support 2858 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2859 2860 Note: You have to set alix.force=1 for boards with Award BIOS. 2861 2862config NET5501 2863 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2864 select GPIOLIB 2865 help 2866 This option enables system support for the Soekris Engineering net5501. 2867 2868config GEOS 2869 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2870 select GPIOLIB 2871 depends on DMI 2872 help 2873 This option enables system support for the Traverse Technologies GEOS. 2874 2875config TS5500 2876 bool "Technologic Systems TS-5500 platform support" 2877 depends on MELAN 2878 select CHECK_SIGNATURE 2879 select NEW_LEDS 2880 select LEDS_CLASS 2881 help 2882 This option enables system support for the Technologic Systems TS-5500. 2883 2884endif # X86_32 2885 2886config AMD_NB 2887 def_bool y 2888 depends on CPU_SUP_AMD && PCI 2889 2890endmenu 2891 2892menu "Binary Emulations" 2893 2894config IA32_EMULATION 2895 bool "IA32 Emulation" 2896 depends on X86_64 2897 select ARCH_WANT_OLD_COMPAT_IPC 2898 select BINFMT_ELF 2899 select COMPAT_OLD_SIGACTION 2900 help 2901 Include code to run legacy 32-bit programs under a 2902 64-bit kernel. You should likely turn this on, unless you're 2903 100% sure that you don't have any 32-bit programs left. 2904 2905config X86_X32_ABI 2906 bool "x32 ABI for 64-bit mode" 2907 depends on X86_64 2908 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2909 # compressed debug sections to x86_x32 properly: 2910 # https://github.com/ClangBuiltLinux/linux/issues/514 2911 # https://github.com/ClangBuiltLinux/linux/issues/1141 2912 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 2913 help 2914 Include code to run binaries for the x32 native 32-bit ABI 2915 for 64-bit processors. An x32 process gets access to the 2916 full 64-bit register file and wide data path while leaving 2917 pointers at 32 bits for smaller memory footprint. 2918 2919config COMPAT_32 2920 def_bool y 2921 depends on IA32_EMULATION || X86_32 2922 select HAVE_UID16 2923 select OLD_SIGSUSPEND3 2924 2925config COMPAT 2926 def_bool y 2927 depends on IA32_EMULATION || X86_X32_ABI 2928 2929config COMPAT_FOR_U64_ALIGNMENT 2930 def_bool y 2931 depends on COMPAT 2932 2933endmenu 2934 2935config HAVE_ATOMIC_IOMAP 2936 def_bool y 2937 depends on X86_32 2938 2939source "arch/x86/kvm/Kconfig" 2940 2941source "arch/x86/Kconfig.assembler" 2942