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_FILTER_PGPROT 80 select ARCH_HAS_FORTIFY_SOURCE 81 select ARCH_HAS_GCOV_PROFILE_ALL 82 select ARCH_HAS_KCOV if X86_64 83 select ARCH_HAS_MEM_ENCRYPT 84 select ARCH_HAS_MEMBARRIER_SYNC_CORE 85 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 86 select ARCH_HAS_PMEM_API if X86_64 87 select ARCH_HAS_PTE_DEVMAP if X86_64 88 select ARCH_HAS_PTE_SPECIAL 89 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 90 select ARCH_HAS_COPY_MC if X86_64 91 select ARCH_HAS_SET_MEMORY 92 select ARCH_HAS_SET_DIRECT_MAP 93 select ARCH_HAS_STRICT_KERNEL_RWX 94 select ARCH_HAS_STRICT_MODULE_RWX 95 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 96 select ARCH_HAS_SYSCALL_WRAPPER 97 select ARCH_HAS_UBSAN_SANITIZE_ALL 98 select ARCH_HAS_DEBUG_WX 99 select ARCH_HAS_ZONE_DMA_SET if EXPERT 100 select ARCH_HAVE_NMI_SAFE_CMPXCHG 101 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 102 select ARCH_MIGHT_HAVE_PC_PARPORT 103 select ARCH_MIGHT_HAVE_PC_SERIO 104 select ARCH_STACKWALK 105 select ARCH_SUPPORTS_ACPI 106 select ARCH_SUPPORTS_ATOMIC_RMW 107 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 108 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 109 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 110 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 111 select ARCH_SUPPORTS_LTO_CLANG 112 select ARCH_SUPPORTS_LTO_CLANG_THIN 113 select ARCH_USE_BUILTIN_BSWAP 114 select ARCH_USE_MEMTEST 115 select ARCH_USE_QUEUED_RWLOCKS 116 select ARCH_USE_QUEUED_SPINLOCKS 117 select ARCH_USE_SYM_ANNOTATIONS 118 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 119 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 120 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 121 select ARCH_WANTS_NO_INSTR 122 select ARCH_WANT_GENERAL_HUGETLB 123 select ARCH_WANT_HUGE_PMD_SHARE 124 select ARCH_WANT_LD_ORPHAN_WARN 125 select ARCH_WANTS_THP_SWAP if X86_64 126 select ARCH_HAS_PARANOID_L1D_FLUSH 127 select BUILDTIME_TABLE_SORT 128 select CLKEVT_I8253 129 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 130 select CLOCKSOURCE_WATCHDOG 131 select DCACHE_WORD_ACCESS 132 select DYNAMIC_SIGFRAME 133 select EDAC_ATOMIC_SCRUB 134 select EDAC_SUPPORT 135 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 136 select GENERIC_CLOCKEVENTS_MIN_ADJUST 137 select GENERIC_CMOS_UPDATE 138 select GENERIC_CPU_AUTOPROBE 139 select GENERIC_CPU_VULNERABILITIES 140 select GENERIC_EARLY_IOREMAP 141 select GENERIC_ENTRY 142 select GENERIC_IOMAP 143 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 144 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 145 select GENERIC_IRQ_MIGRATION if SMP 146 select GENERIC_IRQ_PROBE 147 select GENERIC_IRQ_RESERVATION_MODE 148 select GENERIC_IRQ_SHOW 149 select GENERIC_PENDING_IRQ if SMP 150 select GENERIC_PTDUMP 151 select GENERIC_SMP_IDLE_THREAD 152 select GENERIC_TIME_VSYSCALL 153 select GENERIC_GETTIMEOFDAY 154 select GENERIC_VDSO_TIME_NS 155 select GUP_GET_PTE_LOW_HIGH if X86_PAE 156 select HARDIRQS_SW_RESEND 157 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 158 select HAVE_ACPI_APEI if ACPI 159 select HAVE_ACPI_APEI_NMI if ACPI 160 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 161 select HAVE_ARCH_AUDITSYSCALL 162 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 163 select HAVE_ARCH_HUGE_VMALLOC if X86_64 164 select HAVE_ARCH_JUMP_LABEL 165 select HAVE_ARCH_JUMP_LABEL_RELATIVE 166 select HAVE_ARCH_KASAN if X86_64 167 select HAVE_ARCH_KASAN_VMALLOC if X86_64 168 select HAVE_ARCH_KFENCE 169 select HAVE_ARCH_KGDB 170 select HAVE_ARCH_MMAP_RND_BITS if MMU 171 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 172 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 173 select HAVE_ARCH_PREL32_RELOCATIONS 174 select HAVE_ARCH_SECCOMP_FILTER 175 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 176 select HAVE_ARCH_STACKLEAK 177 select HAVE_ARCH_TRACEHOOK 178 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 179 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 180 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 181 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 182 select HAVE_ARCH_VMAP_STACK if X86_64 183 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 184 select HAVE_ARCH_WITHIN_STACK_FRAMES 185 select HAVE_ASM_MODVERSIONS 186 select HAVE_CMPXCHG_DOUBLE 187 select HAVE_CMPXCHG_LOCAL 188 select HAVE_CONTEXT_TRACKING if X86_64 189 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING 190 select HAVE_C_RECORDMCOUNT 191 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 192 select HAVE_BUILDTIME_MCOUNT_SORT 193 select HAVE_DEBUG_KMEMLEAK 194 select HAVE_DMA_CONTIGUOUS 195 select HAVE_DYNAMIC_FTRACE 196 select HAVE_DYNAMIC_FTRACE_WITH_REGS 197 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 198 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 199 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 200 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 201 select HAVE_EBPF_JIT 202 select HAVE_EFFICIENT_UNALIGNED_ACCESS 203 select HAVE_EISA 204 select HAVE_EXIT_THREAD 205 select HAVE_FAST_GUP 206 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 207 select HAVE_FTRACE_MCOUNT_RECORD 208 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 209 select HAVE_FUNCTION_TRACER 210 select HAVE_GCC_PLUGINS 211 select HAVE_HW_BREAKPOINT 212 select HAVE_IOREMAP_PROT 213 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 214 select HAVE_IRQ_TIME_ACCOUNTING 215 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 216 select HAVE_KERNEL_BZIP2 217 select HAVE_KERNEL_GZIP 218 select HAVE_KERNEL_LZ4 219 select HAVE_KERNEL_LZMA 220 select HAVE_KERNEL_LZO 221 select HAVE_KERNEL_XZ 222 select HAVE_KERNEL_ZSTD 223 select HAVE_KPROBES 224 select HAVE_KPROBES_ON_FTRACE 225 select HAVE_FUNCTION_ERROR_INJECTION 226 select HAVE_KRETPROBES 227 select HAVE_RETHOOK 228 select HAVE_KVM 229 select HAVE_LIVEPATCH if X86_64 230 select HAVE_MIXED_BREAKPOINTS_REGS 231 select HAVE_MOD_ARCH_SPECIFIC 232 select HAVE_MOVE_PMD 233 select HAVE_MOVE_PUD 234 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 235 select HAVE_NMI 236 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 237 select HAVE_OBJTOOL if X86_64 238 select HAVE_OPTPROBES 239 select HAVE_PCSPKR_PLATFORM 240 select HAVE_PERF_EVENTS 241 select HAVE_PERF_EVENTS_NMI 242 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 243 select HAVE_PCI 244 select HAVE_PERF_REGS 245 select HAVE_PERF_USER_STACK_DUMP 246 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 247 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 248 select HAVE_REGS_AND_STACK_ACCESS_API 249 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 250 select HAVE_FUNCTION_ARG_ACCESS_API 251 select HAVE_SETUP_PER_CPU_AREA 252 select HAVE_SOFTIRQ_ON_OWN_STACK 253 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 254 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 255 select HAVE_STATIC_CALL 256 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 257 select HAVE_PREEMPT_DYNAMIC_CALL 258 select HAVE_RSEQ 259 select HAVE_SYSCALL_TRACEPOINTS 260 select HAVE_UNSTABLE_SCHED_CLOCK 261 select HAVE_USER_RETURN_NOTIFIER 262 select HAVE_GENERIC_VDSO 263 select HOTPLUG_SMT if SMP 264 select IRQ_FORCED_THREADING 265 select NEED_PER_CPU_EMBED_FIRST_CHUNK 266 select NEED_PER_CPU_PAGE_FIRST_CHUNK 267 select NEED_SG_DMA_LENGTH 268 select PCI_DOMAINS if PCI 269 select PCI_LOCKLESS_CONFIG if PCI 270 select PERF_EVENTS 271 select RTC_LIB 272 select RTC_MC146818_LIB 273 select SPARSE_IRQ 274 select SRCU 275 select SYSCTL_EXCEPTION_TRACE 276 select THREAD_INFO_IN_TASK 277 select TRACE_IRQFLAGS_SUPPORT 278 select USER_STACKTRACE_SUPPORT 279 select VIRT_TO_BUS 280 select HAVE_ARCH_KCSAN if X86_64 281 select X86_FEATURE_NAMES if PROC_FS 282 select PROC_PID_ARCH_STATUS if PROC_FS 283 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 284 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 285 286config INSTRUCTION_DECODER 287 def_bool y 288 depends on KPROBES || PERF_EVENTS || UPROBES 289 290config OUTPUT_FORMAT 291 string 292 default "elf32-i386" if X86_32 293 default "elf64-x86-64" if X86_64 294 295config LOCKDEP_SUPPORT 296 def_bool y 297 298config STACKTRACE_SUPPORT 299 def_bool y 300 301config MMU 302 def_bool y 303 304config ARCH_MMAP_RND_BITS_MIN 305 default 28 if 64BIT 306 default 8 307 308config ARCH_MMAP_RND_BITS_MAX 309 default 32 if 64BIT 310 default 16 311 312config ARCH_MMAP_RND_COMPAT_BITS_MIN 313 default 8 314 315config ARCH_MMAP_RND_COMPAT_BITS_MAX 316 default 16 317 318config SBUS 319 bool 320 321config GENERIC_ISA_DMA 322 def_bool y 323 depends on ISA_DMA_API 324 325config GENERIC_BUG 326 def_bool y 327 depends on BUG 328 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 329 330config GENERIC_BUG_RELATIVE_POINTERS 331 bool 332 333config ARCH_MAY_HAVE_PC_FDC 334 def_bool y 335 depends on ISA_DMA_API 336 337config GENERIC_CALIBRATE_DELAY 338 def_bool y 339 340config ARCH_HAS_CPU_RELAX 341 def_bool y 342 343config ARCH_HIBERNATION_POSSIBLE 344 def_bool y 345 346config ARCH_NR_GPIO 347 int 348 default 1024 if X86_64 349 default 512 350 351config ARCH_SUSPEND_POSSIBLE 352 def_bool y 353 354config AUDIT_ARCH 355 def_bool y if X86_64 356 357config KASAN_SHADOW_OFFSET 358 hex 359 depends on KASAN 360 default 0xdffffc0000000000 361 362config HAVE_INTEL_TXT 363 def_bool y 364 depends on INTEL_IOMMU && ACPI 365 366config X86_32_SMP 367 def_bool y 368 depends on X86_32 && SMP 369 370config X86_64_SMP 371 def_bool y 372 depends on X86_64 && SMP 373 374config ARCH_SUPPORTS_UPROBES 375 def_bool y 376 377config FIX_EARLYCON_MEM 378 def_bool y 379 380config DYNAMIC_PHYSICAL_MASK 381 bool 382 383config PGTABLE_LEVELS 384 int 385 default 5 if X86_5LEVEL 386 default 4 if X86_64 387 default 3 if X86_PAE 388 default 2 389 390config CC_HAS_SANE_STACKPROTECTOR 391 bool 392 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT 393 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC)) 394 help 395 We have to make sure stack protector is unconditionally disabled if 396 the compiler produces broken code or if it does not let us control 397 the segment on 32-bit kernels. 398 399menu "Processor type and features" 400 401config SMP 402 bool "Symmetric multi-processing support" 403 help 404 This enables support for systems with more than one CPU. If you have 405 a system with only one CPU, say N. If you have a system with more 406 than one CPU, say Y. 407 408 If you say N here, the kernel will run on uni- and multiprocessor 409 machines, but will use only one CPU of a multiprocessor machine. If 410 you say Y here, the kernel will run on many, but not all, 411 uniprocessor machines. On a uniprocessor machine, the kernel 412 will run faster if you say N here. 413 414 Note that if you say Y here and choose architecture "586" or 415 "Pentium" under "Processor family", the kernel will not work on 486 416 architectures. Similarly, multiprocessor kernels for the "PPro" 417 architecture may not work on all Pentium based boards. 418 419 People using multiprocessor machines who say Y here should also say 420 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 421 Management" code will be disabled if you say Y here. 422 423 See also <file:Documentation/x86/i386/IO-APIC.rst>, 424 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 425 <http://www.tldp.org/docs.html#howto>. 426 427 If you don't know what to do here, say N. 428 429config X86_FEATURE_NAMES 430 bool "Processor feature human-readable names" if EMBEDDED 431 default y 432 help 433 This option compiles in a table of x86 feature bits and corresponding 434 names. This is required to support /proc/cpuinfo and a few kernel 435 messages. You can disable this to save space, at the expense of 436 making those few kernel messages show numeric feature bits instead. 437 438 If in doubt, say Y. 439 440config X86_X2APIC 441 bool "Support x2apic" 442 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 443 help 444 This enables x2apic support on CPUs that have this feature. 445 446 This allows 32-bit apic IDs (so it can support very large systems), 447 and accesses the local apic via MSRs not via mmio. 448 449 If you don't know what to do here, say N. 450 451config X86_MPPARSE 452 bool "Enable MPS table" if ACPI 453 default y 454 depends on X86_LOCAL_APIC 455 help 456 For old smp systems that do not have proper acpi support. Newer systems 457 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 458 459config GOLDFISH 460 def_bool y 461 depends on X86_GOLDFISH 462 463config RETPOLINE 464 bool "Avoid speculative indirect branches in kernel" 465 select OBJTOOL if HAVE_OBJTOOL 466 default y 467 help 468 Compile kernel with the retpoline compiler options to guard against 469 kernel-to-user data leaks by avoiding speculative indirect 470 branches. Requires a compiler with -mindirect-branch=thunk-extern 471 support for full protection. The kernel may run slower. 472 473config CC_HAS_SLS 474 def_bool $(cc-option,-mharden-sls=all) 475 476config SLS 477 bool "Mitigate Straight-Line-Speculation" 478 depends on CC_HAS_SLS && X86_64 479 select OBJTOOL if HAVE_OBJTOOL 480 default n 481 help 482 Compile the kernel with straight-line-speculation options to guard 483 against straight line speculation. The kernel image might be slightly 484 larger. 485 486config X86_CPU_RESCTRL 487 bool "x86 CPU resource control support" 488 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 489 select KERNFS 490 select PROC_CPU_RESCTRL if PROC_FS 491 help 492 Enable x86 CPU resource control support. 493 494 Provide support for the allocation and monitoring of system resources 495 usage by the CPU. 496 497 Intel calls this Intel Resource Director Technology 498 (Intel(R) RDT). More information about RDT can be found in the 499 Intel x86 Architecture Software Developer Manual. 500 501 AMD calls this AMD Platform Quality of Service (AMD QoS). 502 More information about AMD QoS can be found in the AMD64 Technology 503 Platform Quality of Service Extensions manual. 504 505 Say N if unsure. 506 507if X86_32 508config X86_BIGSMP 509 bool "Support for big SMP systems with more than 8 CPUs" 510 depends on SMP 511 help 512 This option is needed for the systems that have more than 8 CPUs. 513 514config X86_EXTENDED_PLATFORM 515 bool "Support for extended (non-PC) x86 platforms" 516 default y 517 help 518 If you disable this option then the kernel will only support 519 standard PC platforms. (which covers the vast majority of 520 systems out there.) 521 522 If you enable this option then you'll be able to select support 523 for the following (non-PC) 32 bit x86 platforms: 524 Goldfish (Android emulator) 525 AMD Elan 526 RDC R-321x SoC 527 SGI 320/540 (Visual Workstation) 528 STA2X11-based (e.g. Northville) 529 Moorestown MID devices 530 531 If you have one of these systems, or if you want to build a 532 generic distribution kernel, say Y here - otherwise say N. 533endif 534 535if X86_64 536config X86_EXTENDED_PLATFORM 537 bool "Support for extended (non-PC) x86 platforms" 538 default y 539 help 540 If you disable this option then the kernel will only support 541 standard PC platforms. (which covers the vast majority of 542 systems out there.) 543 544 If you enable this option then you'll be able to select support 545 for the following (non-PC) 64 bit x86 platforms: 546 Numascale NumaChip 547 ScaleMP vSMP 548 SGI Ultraviolet 549 550 If you have one of these systems, or if you want to build a 551 generic distribution kernel, say Y here - otherwise say N. 552endif 553# This is an alphabetically sorted list of 64 bit extended platforms 554# Please maintain the alphabetic order if and when there are additions 555config X86_NUMACHIP 556 bool "Numascale NumaChip" 557 depends on X86_64 558 depends on X86_EXTENDED_PLATFORM 559 depends on NUMA 560 depends on SMP 561 depends on X86_X2APIC 562 depends on PCI_MMCONFIG 563 help 564 Adds support for Numascale NumaChip large-SMP systems. Needed to 565 enable more than ~168 cores. 566 If you don't have one of these, you should say N here. 567 568config X86_VSMP 569 bool "ScaleMP vSMP" 570 select HYPERVISOR_GUEST 571 select PARAVIRT 572 depends on X86_64 && PCI 573 depends on X86_EXTENDED_PLATFORM 574 depends on SMP 575 help 576 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 577 supposed to run on these EM64T-based machines. Only choose this option 578 if you have one of these machines. 579 580config X86_UV 581 bool "SGI Ultraviolet" 582 depends on X86_64 583 depends on X86_EXTENDED_PLATFORM 584 depends on NUMA 585 depends on EFI 586 depends on KEXEC_CORE 587 depends on X86_X2APIC 588 depends on PCI 589 help 590 This option is needed in order to support SGI Ultraviolet systems. 591 If you don't have one of these, you should say N here. 592 593# Following is an alphabetically sorted list of 32 bit extended platforms 594# Please maintain the alphabetic order if and when there are additions 595 596config X86_GOLDFISH 597 bool "Goldfish (Virtual Platform)" 598 depends on X86_EXTENDED_PLATFORM 599 help 600 Enable support for the Goldfish virtual platform used primarily 601 for Android development. Unless you are building for the Android 602 Goldfish emulator say N here. 603 604config X86_INTEL_CE 605 bool "CE4100 TV platform" 606 depends on PCI 607 depends on PCI_GODIRECT 608 depends on X86_IO_APIC 609 depends on X86_32 610 depends on X86_EXTENDED_PLATFORM 611 select X86_REBOOTFIXUPS 612 select OF 613 select OF_EARLY_FLATTREE 614 help 615 Select for the Intel CE media processor (CE4100) SOC. 616 This option compiles in support for the CE4100 SOC for settop 617 boxes and media devices. 618 619config X86_INTEL_MID 620 bool "Intel MID platform support" 621 depends on X86_EXTENDED_PLATFORM 622 depends on X86_PLATFORM_DEVICES 623 depends on PCI 624 depends on X86_64 || (PCI_GOANY && X86_32) 625 depends on X86_IO_APIC 626 select I2C 627 select DW_APB_TIMER 628 select INTEL_SCU_PCI 629 help 630 Select to build a kernel capable of supporting Intel MID (Mobile 631 Internet Device) platform systems which do not have the PCI legacy 632 interfaces. If you are building for a PC class system say N here. 633 634 Intel MID platforms are based on an Intel processor and chipset which 635 consume less power than most of the x86 derivatives. 636 637config X86_INTEL_QUARK 638 bool "Intel Quark platform support" 639 depends on X86_32 640 depends on X86_EXTENDED_PLATFORM 641 depends on X86_PLATFORM_DEVICES 642 depends on X86_TSC 643 depends on PCI 644 depends on PCI_GOANY 645 depends on X86_IO_APIC 646 select IOSF_MBI 647 select INTEL_IMR 648 select COMMON_CLK 649 help 650 Select to include support for Quark X1000 SoC. 651 Say Y here if you have a Quark based system such as the Arduino 652 compatible Intel Galileo. 653 654config X86_INTEL_LPSS 655 bool "Intel Low Power Subsystem Support" 656 depends on X86 && ACPI && PCI 657 select COMMON_CLK 658 select PINCTRL 659 select IOSF_MBI 660 help 661 Select to build support for Intel Low Power Subsystem such as 662 found on Intel Lynxpoint PCH. Selecting this option enables 663 things like clock tree (common clock framework) and pincontrol 664 which are needed by the LPSS peripheral drivers. 665 666config X86_AMD_PLATFORM_DEVICE 667 bool "AMD ACPI2Platform devices support" 668 depends on ACPI 669 select COMMON_CLK 670 select PINCTRL 671 help 672 Select to interpret AMD specific ACPI device to platform device 673 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 674 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 675 implemented under PINCTRL subsystem. 676 677config IOSF_MBI 678 tristate "Intel SoC IOSF Sideband support for SoC platforms" 679 depends on PCI 680 help 681 This option enables sideband register access support for Intel SoC 682 platforms. On these platforms the IOSF sideband is used in lieu of 683 MSR's for some register accesses, mostly but not limited to thermal 684 and power. Drivers may query the availability of this device to 685 determine if they need the sideband in order to work on these 686 platforms. The sideband is available on the following SoC products. 687 This list is not meant to be exclusive. 688 - BayTrail 689 - Braswell 690 - Quark 691 692 You should say Y if you are running a kernel on one of these SoC's. 693 694config IOSF_MBI_DEBUG 695 bool "Enable IOSF sideband access through debugfs" 696 depends on IOSF_MBI && DEBUG_FS 697 help 698 Select this option to expose the IOSF sideband access registers (MCR, 699 MDR, MCRX) through debugfs to write and read register information from 700 different units on the SoC. This is most useful for obtaining device 701 state information for debug and analysis. As this is a general access 702 mechanism, users of this option would have specific knowledge of the 703 device they want to access. 704 705 If you don't require the option or are in doubt, say N. 706 707config X86_RDC321X 708 bool "RDC R-321x SoC" 709 depends on X86_32 710 depends on X86_EXTENDED_PLATFORM 711 select M486 712 select X86_REBOOTFIXUPS 713 help 714 This option is needed for RDC R-321x system-on-chip, also known 715 as R-8610-(G). 716 If you don't have one of these chips, you should say N here. 717 718config X86_32_NON_STANDARD 719 bool "Support non-standard 32-bit SMP architectures" 720 depends on X86_32 && SMP 721 depends on X86_EXTENDED_PLATFORM 722 help 723 This option compiles in the bigsmp and STA2X11 default 724 subarchitectures. It is intended for a generic binary 725 kernel. If you select them all, kernel will probe it one by 726 one and will fallback to default. 727 728# Alphabetically sorted list of Non standard 32 bit platforms 729 730config X86_SUPPORTS_MEMORY_FAILURE 731 def_bool y 732 # MCE code calls memory_failure(): 733 depends on X86_MCE 734 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 735 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 736 depends on X86_64 || !SPARSEMEM 737 select ARCH_SUPPORTS_MEMORY_FAILURE 738 739config STA2X11 740 bool "STA2X11 Companion Chip Support" 741 depends on X86_32_NON_STANDARD && PCI 742 select SWIOTLB 743 select MFD_STA2X11 744 select GPIOLIB 745 help 746 This adds support for boards based on the STA2X11 IO-Hub, 747 a.k.a. "ConneXt". The chip is used in place of the standard 748 PC chipset, so all "standard" peripherals are missing. If this 749 option is selected the kernel will still be able to boot on 750 standard PC machines. 751 752config X86_32_IRIS 753 tristate "Eurobraille/Iris poweroff module" 754 depends on X86_32 755 help 756 The Iris machines from EuroBraille do not have APM or ACPI support 757 to shut themselves down properly. A special I/O sequence is 758 needed to do so, which is what this module does at 759 kernel shutdown. 760 761 This is only for Iris machines from EuroBraille. 762 763 If unused, say N. 764 765config SCHED_OMIT_FRAME_POINTER 766 def_bool y 767 prompt "Single-depth WCHAN output" 768 depends on X86 769 help 770 Calculate simpler /proc/<PID>/wchan values. If this option 771 is disabled then wchan values will recurse back to the 772 caller function. This provides more accurate wchan values, 773 at the expense of slightly more scheduling overhead. 774 775 If in doubt, say "Y". 776 777menuconfig HYPERVISOR_GUEST 778 bool "Linux guest support" 779 help 780 Say Y here to enable options for running Linux under various hyper- 781 visors. This option enables basic hypervisor detection and platform 782 setup. 783 784 If you say N, all options in this submenu will be skipped and 785 disabled, and Linux guest support won't be built in. 786 787if HYPERVISOR_GUEST 788 789config PARAVIRT 790 bool "Enable paravirtualization code" 791 depends on HAVE_STATIC_CALL 792 help 793 This changes the kernel so it can modify itself when it is run 794 under a hypervisor, potentially improving performance significantly 795 over full virtualization. However, when run without a hypervisor 796 the kernel is theoretically slower and slightly larger. 797 798config PARAVIRT_XXL 799 bool 800 801config PARAVIRT_DEBUG 802 bool "paravirt-ops debugging" 803 depends on PARAVIRT && DEBUG_KERNEL 804 help 805 Enable to debug paravirt_ops internals. Specifically, BUG if 806 a paravirt_op is missing when it is called. 807 808config PARAVIRT_SPINLOCKS 809 bool "Paravirtualization layer for spinlocks" 810 depends on PARAVIRT && SMP 811 help 812 Paravirtualized spinlocks allow a pvops backend to replace the 813 spinlock implementation with something virtualization-friendly 814 (for example, block the virtual CPU rather than spinning). 815 816 It has a minimal impact on native kernels and gives a nice performance 817 benefit on paravirtualized KVM / Xen kernels. 818 819 If you are unsure how to answer this question, answer Y. 820 821config X86_HV_CALLBACK_VECTOR 822 def_bool n 823 824source "arch/x86/xen/Kconfig" 825 826config KVM_GUEST 827 bool "KVM Guest support (including kvmclock)" 828 depends on PARAVIRT 829 select PARAVIRT_CLOCK 830 select ARCH_CPUIDLE_HALTPOLL 831 select X86_HV_CALLBACK_VECTOR 832 default y 833 help 834 This option enables various optimizations for running under the KVM 835 hypervisor. It includes a paravirtualized clock, so that instead 836 of relying on a PIT (or probably other) emulation by the 837 underlying device model, the host provides the guest with 838 timing infrastructure such as time of day, and system time 839 840config ARCH_CPUIDLE_HALTPOLL 841 def_bool n 842 prompt "Disable host haltpoll when loading haltpoll driver" 843 help 844 If virtualized under KVM, disable host haltpoll. 845 846config PVH 847 bool "Support for running PVH guests" 848 help 849 This option enables the PVH entry point for guest virtual machines 850 as specified in the x86/HVM direct boot ABI. 851 852config PARAVIRT_TIME_ACCOUNTING 853 bool "Paravirtual steal time accounting" 854 depends on PARAVIRT 855 help 856 Select this option to enable fine granularity task steal time 857 accounting. Time spent executing other tasks in parallel with 858 the current vCPU is discounted from the vCPU power. To account for 859 that, there can be a small performance impact. 860 861 If in doubt, say N here. 862 863config PARAVIRT_CLOCK 864 bool 865 866config JAILHOUSE_GUEST 867 bool "Jailhouse non-root cell support" 868 depends on X86_64 && PCI 869 select X86_PM_TIMER 870 help 871 This option allows to run Linux as guest in a Jailhouse non-root 872 cell. You can leave this option disabled if you only want to start 873 Jailhouse and run Linux afterwards in the root cell. 874 875config ACRN_GUEST 876 bool "ACRN Guest support" 877 depends on X86_64 878 select X86_HV_CALLBACK_VECTOR 879 help 880 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 881 a flexible, lightweight reference open-source hypervisor, built with 882 real-time and safety-criticality in mind. It is built for embedded 883 IOT with small footprint and real-time features. More details can be 884 found in https://projectacrn.org/. 885 886config INTEL_TDX_GUEST 887 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 888 depends on X86_64 && CPU_SUP_INTEL 889 depends on X86_X2APIC 890 select ARCH_HAS_CC_PLATFORM 891 select X86_MEM_ENCRYPT 892 select X86_MCE 893 help 894 Support running as a guest under Intel TDX. Without this support, 895 the guest kernel can not boot or run under TDX. 896 TDX includes memory encryption and integrity capabilities 897 which protect the confidentiality and integrity of guest 898 memory contents and CPU state. TDX guests are protected from 899 some attacks from the VMM. 900 901endif #HYPERVISOR_GUEST 902 903source "arch/x86/Kconfig.cpu" 904 905config HPET_TIMER 906 def_bool X86_64 907 prompt "HPET Timer Support" if X86_32 908 help 909 Use the IA-PC HPET (High Precision Event Timer) to manage 910 time in preference to the PIT and RTC, if a HPET is 911 present. 912 HPET is the next generation timer replacing legacy 8254s. 913 The HPET provides a stable time base on SMP 914 systems, unlike the TSC, but it is more expensive to access, 915 as it is off-chip. The interface used is documented 916 in the HPET spec, revision 1. 917 918 You can safely choose Y here. However, HPET will only be 919 activated if the platform and the BIOS support this feature. 920 Otherwise the 8254 will be used for timing services. 921 922 Choose N to continue using the legacy 8254 timer. 923 924config HPET_EMULATE_RTC 925 def_bool y 926 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 927 928# Mark as expert because too many people got it wrong. 929# The code disables itself when not needed. 930config DMI 931 default y 932 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 933 bool "Enable DMI scanning" if EXPERT 934 help 935 Enabled scanning of DMI to identify machine quirks. Say Y 936 here unless you have verified that your setup is not 937 affected by entries in the DMI blacklist. Required by PNP 938 BIOS code. 939 940config GART_IOMMU 941 bool "Old AMD GART IOMMU support" 942 select DMA_OPS 943 select IOMMU_HELPER 944 select SWIOTLB 945 depends on X86_64 && PCI && AMD_NB 946 help 947 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 948 GART based hardware IOMMUs. 949 950 The GART supports full DMA access for devices with 32-bit access 951 limitations, on systems with more than 3 GB. This is usually needed 952 for USB, sound, many IDE/SATA chipsets and some other devices. 953 954 Newer systems typically have a modern AMD IOMMU, supported via 955 the CONFIG_AMD_IOMMU=y config option. 956 957 In normal configurations this driver is only active when needed: 958 there's more than 3 GB of memory and the system contains a 959 32-bit limited device. 960 961 If unsure, say Y. 962 963config MAXSMP 964 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 965 depends on X86_64 && SMP && DEBUG_KERNEL 966 select CPUMASK_OFFSTACK 967 help 968 Enable maximum number of CPUS and NUMA Nodes for this architecture. 969 If unsure, say N. 970 971# 972# The maximum number of CPUs supported: 973# 974# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 975# and which can be configured interactively in the 976# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 977# 978# The ranges are different on 32-bit and 64-bit kernels, depending on 979# hardware capabilities and scalability features of the kernel. 980# 981# ( If MAXSMP is enabled we just use the highest possible value and disable 982# interactive configuration. ) 983# 984 985config NR_CPUS_RANGE_BEGIN 986 int 987 default NR_CPUS_RANGE_END if MAXSMP 988 default 1 if !SMP 989 default 2 990 991config NR_CPUS_RANGE_END 992 int 993 depends on X86_32 994 default 64 if SMP && X86_BIGSMP 995 default 8 if SMP && !X86_BIGSMP 996 default 1 if !SMP 997 998config NR_CPUS_RANGE_END 999 int 1000 depends on X86_64 1001 default 8192 if SMP && CPUMASK_OFFSTACK 1002 default 512 if SMP && !CPUMASK_OFFSTACK 1003 default 1 if !SMP 1004 1005config NR_CPUS_DEFAULT 1006 int 1007 depends on X86_32 1008 default 32 if X86_BIGSMP 1009 default 8 if SMP 1010 default 1 if !SMP 1011 1012config NR_CPUS_DEFAULT 1013 int 1014 depends on X86_64 1015 default 8192 if MAXSMP 1016 default 64 if SMP 1017 default 1 if !SMP 1018 1019config NR_CPUS 1020 int "Maximum number of CPUs" if SMP && !MAXSMP 1021 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1022 default NR_CPUS_DEFAULT 1023 help 1024 This allows you to specify the maximum number of CPUs which this 1025 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1026 supported value is 8192, otherwise the maximum value is 512. The 1027 minimum value which makes sense is 2. 1028 1029 This is purely to save memory: each supported CPU adds about 8KB 1030 to the kernel image. 1031 1032config SCHED_CLUSTER 1033 bool "Cluster scheduler support" 1034 depends on SMP 1035 default y 1036 help 1037 Cluster scheduler support improves the CPU scheduler's decision 1038 making when dealing with machines that have clusters of CPUs. 1039 Cluster usually means a couple of CPUs which are placed closely 1040 by sharing mid-level caches, last-level cache tags or internal 1041 busses. 1042 1043config SCHED_SMT 1044 def_bool y if SMP 1045 1046config SCHED_MC 1047 def_bool y 1048 prompt "Multi-core scheduler support" 1049 depends on SMP 1050 help 1051 Multi-core scheduler support improves the CPU scheduler's decision 1052 making when dealing with multi-core CPU chips at a cost of slightly 1053 increased overhead in some places. If unsure say N here. 1054 1055config SCHED_MC_PRIO 1056 bool "CPU core priorities scheduler support" 1057 depends on SCHED_MC && CPU_SUP_INTEL 1058 select X86_INTEL_PSTATE 1059 select CPU_FREQ 1060 default y 1061 help 1062 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1063 core ordering determined at manufacturing time, which allows 1064 certain cores to reach higher turbo frequencies (when running 1065 single threaded workloads) than others. 1066 1067 Enabling this kernel feature teaches the scheduler about 1068 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1069 scheduler's CPU selection logic accordingly, so that higher 1070 overall system performance can be achieved. 1071 1072 This feature will have no effect on CPUs without this feature. 1073 1074 If unsure say Y here. 1075 1076config UP_LATE_INIT 1077 def_bool y 1078 depends on !SMP && X86_LOCAL_APIC 1079 1080config X86_UP_APIC 1081 bool "Local APIC support on uniprocessors" if !PCI_MSI 1082 default PCI_MSI 1083 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1084 help 1085 A local APIC (Advanced Programmable Interrupt Controller) is an 1086 integrated interrupt controller in the CPU. If you have a single-CPU 1087 system which has a processor with a local APIC, you can say Y here to 1088 enable and use it. If you say Y here even though your machine doesn't 1089 have a local APIC, then the kernel will still run with no slowdown at 1090 all. The local APIC supports CPU-generated self-interrupts (timer, 1091 performance counters), and the NMI watchdog which detects hard 1092 lockups. 1093 1094config X86_UP_IOAPIC 1095 bool "IO-APIC support on uniprocessors" 1096 depends on X86_UP_APIC 1097 help 1098 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1099 SMP-capable replacement for PC-style interrupt controllers. Most 1100 SMP systems and many recent uniprocessor systems have one. 1101 1102 If you have a single-CPU system with an IO-APIC, you can say Y here 1103 to use it. If you say Y here even though your machine doesn't have 1104 an IO-APIC, then the kernel will still run with no slowdown at all. 1105 1106config X86_LOCAL_APIC 1107 def_bool y 1108 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1109 select IRQ_DOMAIN_HIERARCHY 1110 select PCI_MSI_IRQ_DOMAIN if PCI_MSI 1111 1112config X86_IO_APIC 1113 def_bool y 1114 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1115 1116config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1117 bool "Reroute for broken boot IRQs" 1118 depends on X86_IO_APIC 1119 help 1120 This option enables a workaround that fixes a source of 1121 spurious interrupts. This is recommended when threaded 1122 interrupt handling is used on systems where the generation of 1123 superfluous "boot interrupts" cannot be disabled. 1124 1125 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1126 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1127 kernel does during interrupt handling). On chipsets where this 1128 boot IRQ generation cannot be disabled, this workaround keeps 1129 the original IRQ line masked so that only the equivalent "boot 1130 IRQ" is delivered to the CPUs. The workaround also tells the 1131 kernel to set up the IRQ handler on the boot IRQ line. In this 1132 way only one interrupt is delivered to the kernel. Otherwise 1133 the spurious second interrupt may cause the kernel to bring 1134 down (vital) interrupt lines. 1135 1136 Only affects "broken" chipsets. Interrupt sharing may be 1137 increased on these systems. 1138 1139config X86_MCE 1140 bool "Machine Check / overheating reporting" 1141 select GENERIC_ALLOCATOR 1142 default y 1143 help 1144 Machine Check support allows the processor to notify the 1145 kernel if it detects a problem (e.g. overheating, data corruption). 1146 The action the kernel takes depends on the severity of the problem, 1147 ranging from warning messages to halting the machine. 1148 1149config X86_MCELOG_LEGACY 1150 bool "Support for deprecated /dev/mcelog character device" 1151 depends on X86_MCE 1152 help 1153 Enable support for /dev/mcelog which is needed by the old mcelog 1154 userspace logging daemon. Consider switching to the new generation 1155 rasdaemon solution. 1156 1157config X86_MCE_INTEL 1158 def_bool y 1159 prompt "Intel MCE features" 1160 depends on X86_MCE && X86_LOCAL_APIC 1161 help 1162 Additional support for intel specific MCE features such as 1163 the thermal monitor. 1164 1165config X86_MCE_AMD 1166 def_bool y 1167 prompt "AMD MCE features" 1168 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1169 help 1170 Additional support for AMD specific MCE features such as 1171 the DRAM Error Threshold. 1172 1173config X86_ANCIENT_MCE 1174 bool "Support for old Pentium 5 / WinChip machine checks" 1175 depends on X86_32 && X86_MCE 1176 help 1177 Include support for machine check handling on old Pentium 5 or WinChip 1178 systems. These typically need to be enabled explicitly on the command 1179 line. 1180 1181config X86_MCE_THRESHOLD 1182 depends on X86_MCE_AMD || X86_MCE_INTEL 1183 def_bool y 1184 1185config X86_MCE_INJECT 1186 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1187 tristate "Machine check injector support" 1188 help 1189 Provide support for injecting machine checks for testing purposes. 1190 If you don't know what a machine check is and you don't do kernel 1191 QA it is safe to say n. 1192 1193source "arch/x86/events/Kconfig" 1194 1195config X86_LEGACY_VM86 1196 bool "Legacy VM86 support" 1197 depends on X86_32 1198 help 1199 This option allows user programs to put the CPU into V8086 1200 mode, which is an 80286-era approximation of 16-bit real mode. 1201 1202 Some very old versions of X and/or vbetool require this option 1203 for user mode setting. Similarly, DOSEMU will use it if 1204 available to accelerate real mode DOS programs. However, any 1205 recent version of DOSEMU, X, or vbetool should be fully 1206 functional even without kernel VM86 support, as they will all 1207 fall back to software emulation. Nevertheless, if you are using 1208 a 16-bit DOS program where 16-bit performance matters, vm86 1209 mode might be faster than emulation and you might want to 1210 enable this option. 1211 1212 Note that any app that works on a 64-bit kernel is unlikely to 1213 need this option, as 64-bit kernels don't, and can't, support 1214 V8086 mode. This option is also unrelated to 16-bit protected 1215 mode and is not needed to run most 16-bit programs under Wine. 1216 1217 Enabling this option increases the complexity of the kernel 1218 and slows down exception handling a tiny bit. 1219 1220 If unsure, say N here. 1221 1222config VM86 1223 bool 1224 default X86_LEGACY_VM86 1225 1226config X86_16BIT 1227 bool "Enable support for 16-bit segments" if EXPERT 1228 default y 1229 depends on MODIFY_LDT_SYSCALL 1230 help 1231 This option is required by programs like Wine to run 16-bit 1232 protected mode legacy code on x86 processors. Disabling 1233 this option saves about 300 bytes on i386, or around 6K text 1234 plus 16K runtime memory on x86-64, 1235 1236config X86_ESPFIX32 1237 def_bool y 1238 depends on X86_16BIT && X86_32 1239 1240config X86_ESPFIX64 1241 def_bool y 1242 depends on X86_16BIT && X86_64 1243 1244config X86_VSYSCALL_EMULATION 1245 bool "Enable vsyscall emulation" if EXPERT 1246 default y 1247 depends on X86_64 1248 help 1249 This enables emulation of the legacy vsyscall page. Disabling 1250 it is roughly equivalent to booting with vsyscall=none, except 1251 that it will also disable the helpful warning if a program 1252 tries to use a vsyscall. With this option set to N, offending 1253 programs will just segfault, citing addresses of the form 1254 0xffffffffff600?00. 1255 1256 This option is required by many programs built before 2013, and 1257 care should be used even with newer programs if set to N. 1258 1259 Disabling this option saves about 7K of kernel size and 1260 possibly 4K of additional runtime pagetable memory. 1261 1262config X86_IOPL_IOPERM 1263 bool "IOPERM and IOPL Emulation" 1264 default y 1265 help 1266 This enables the ioperm() and iopl() syscalls which are necessary 1267 for legacy applications. 1268 1269 Legacy IOPL support is an overbroad mechanism which allows user 1270 space aside of accessing all 65536 I/O ports also to disable 1271 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1272 capabilities and permission from potentially active security 1273 modules. 1274 1275 The emulation restricts the functionality of the syscall to 1276 only allowing the full range I/O port access, but prevents the 1277 ability to disable interrupts from user space which would be 1278 granted if the hardware IOPL mechanism would be used. 1279 1280config TOSHIBA 1281 tristate "Toshiba Laptop support" 1282 depends on X86_32 1283 help 1284 This adds a driver to safely access the System Management Mode of 1285 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1286 not work on models with a Phoenix BIOS. The System Management Mode 1287 is used to set the BIOS and power saving options on Toshiba portables. 1288 1289 For information on utilities to make use of this driver see the 1290 Toshiba Linux utilities web site at: 1291 <http://www.buzzard.org.uk/toshiba/>. 1292 1293 Say Y if you intend to run this kernel on a Toshiba portable. 1294 Say N otherwise. 1295 1296config X86_REBOOTFIXUPS 1297 bool "Enable X86 board specific fixups for reboot" 1298 depends on X86_32 1299 help 1300 This enables chipset and/or board specific fixups to be done 1301 in order to get reboot to work correctly. This is only needed on 1302 some combinations of hardware and BIOS. The symptom, for which 1303 this config is intended, is when reboot ends with a stalled/hung 1304 system. 1305 1306 Currently, the only fixup is for the Geode machines using 1307 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1308 1309 Say Y if you want to enable the fixup. Currently, it's safe to 1310 enable this option even if you don't need it. 1311 Say N otherwise. 1312 1313config MICROCODE 1314 bool "CPU microcode loading support" 1315 default y 1316 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1317 help 1318 If you say Y here, you will be able to update the microcode on 1319 Intel and AMD processors. The Intel support is for the IA32 family, 1320 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1321 AMD support is for families 0x10 and later. You will obviously need 1322 the actual microcode binary data itself which is not shipped with 1323 the Linux kernel. 1324 1325 The preferred method to load microcode from a detached initrd is described 1326 in Documentation/x86/microcode.rst. For that you need to enable 1327 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1328 initrd for microcode blobs. 1329 1330 In addition, you can build the microcode into the kernel. For that you 1331 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1332 config option. 1333 1334config MICROCODE_INTEL 1335 bool "Intel microcode loading support" 1336 depends on CPU_SUP_INTEL && MICROCODE 1337 default MICROCODE 1338 help 1339 This options enables microcode patch loading support for Intel 1340 processors. 1341 1342 For the current Intel microcode data package go to 1343 <https://downloadcenter.intel.com> and search for 1344 'Linux Processor Microcode Data File'. 1345 1346config MICROCODE_AMD 1347 bool "AMD microcode loading support" 1348 depends on CPU_SUP_AMD && MICROCODE 1349 help 1350 If you select this option, microcode patch loading support for AMD 1351 processors will be enabled. 1352 1353config MICROCODE_OLD_INTERFACE 1354 bool "Ancient loading interface (DEPRECATED)" 1355 default n 1356 depends on MICROCODE 1357 help 1358 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface 1359 which was used by userspace tools like iucode_tool and microcode.ctl. 1360 It is inadequate because it runs too late to be able to properly 1361 load microcode on a machine and it needs special tools. Instead, you 1362 should've switched to the early loading method with the initrd or 1363 builtin microcode by now: Documentation/x86/microcode.rst 1364 1365config X86_MSR 1366 tristate "/dev/cpu/*/msr - Model-specific register support" 1367 help 1368 This device gives privileged processes access to the x86 1369 Model-Specific Registers (MSRs). It is a character device with 1370 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1371 MSR accesses are directed to a specific CPU on multi-processor 1372 systems. 1373 1374config X86_CPUID 1375 tristate "/dev/cpu/*/cpuid - CPU information support" 1376 help 1377 This device gives processes access to the x86 CPUID instruction to 1378 be executed on a specific processor. It is a character device 1379 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1380 /dev/cpu/31/cpuid. 1381 1382choice 1383 prompt "High Memory Support" 1384 default HIGHMEM4G 1385 depends on X86_32 1386 1387config NOHIGHMEM 1388 bool "off" 1389 help 1390 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1391 However, the address space of 32-bit x86 processors is only 4 1392 Gigabytes large. That means that, if you have a large amount of 1393 physical memory, not all of it can be "permanently mapped" by the 1394 kernel. The physical memory that's not permanently mapped is called 1395 "high memory". 1396 1397 If you are compiling a kernel which will never run on a machine with 1398 more than 1 Gigabyte total physical RAM, answer "off" here (default 1399 choice and suitable for most users). This will result in a "3GB/1GB" 1400 split: 3GB are mapped so that each process sees a 3GB virtual memory 1401 space and the remaining part of the 4GB virtual memory space is used 1402 by the kernel to permanently map as much physical memory as 1403 possible. 1404 1405 If the machine has between 1 and 4 Gigabytes physical RAM, then 1406 answer "4GB" here. 1407 1408 If more than 4 Gigabytes is used then answer "64GB" here. This 1409 selection turns Intel PAE (Physical Address Extension) mode on. 1410 PAE implements 3-level paging on IA32 processors. PAE is fully 1411 supported by Linux, PAE mode is implemented on all recent Intel 1412 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1413 then the kernel will not boot on CPUs that don't support PAE! 1414 1415 The actual amount of total physical memory will either be 1416 auto detected or can be forced by using a kernel command line option 1417 such as "mem=256M". (Try "man bootparam" or see the documentation of 1418 your boot loader (lilo or loadlin) about how to pass options to the 1419 kernel at boot time.) 1420 1421 If unsure, say "off". 1422 1423config HIGHMEM4G 1424 bool "4GB" 1425 help 1426 Select this if you have a 32-bit processor and between 1 and 4 1427 gigabytes of physical RAM. 1428 1429config HIGHMEM64G 1430 bool "64GB" 1431 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1432 select X86_PAE 1433 help 1434 Select this if you have a 32-bit processor and more than 4 1435 gigabytes of physical RAM. 1436 1437endchoice 1438 1439choice 1440 prompt "Memory split" if EXPERT 1441 default VMSPLIT_3G 1442 depends on X86_32 1443 help 1444 Select the desired split between kernel and user memory. 1445 1446 If the address range available to the kernel is less than the 1447 physical memory installed, the remaining memory will be available 1448 as "high memory". Accessing high memory is a little more costly 1449 than low memory, as it needs to be mapped into the kernel first. 1450 Note that increasing the kernel address space limits the range 1451 available to user programs, making the address space there 1452 tighter. Selecting anything other than the default 3G/1G split 1453 will also likely make your kernel incompatible with binary-only 1454 kernel modules. 1455 1456 If you are not absolutely sure what you are doing, leave this 1457 option alone! 1458 1459 config VMSPLIT_3G 1460 bool "3G/1G user/kernel split" 1461 config VMSPLIT_3G_OPT 1462 depends on !X86_PAE 1463 bool "3G/1G user/kernel split (for full 1G low memory)" 1464 config VMSPLIT_2G 1465 bool "2G/2G user/kernel split" 1466 config VMSPLIT_2G_OPT 1467 depends on !X86_PAE 1468 bool "2G/2G user/kernel split (for full 2G low memory)" 1469 config VMSPLIT_1G 1470 bool "1G/3G user/kernel split" 1471endchoice 1472 1473config PAGE_OFFSET 1474 hex 1475 default 0xB0000000 if VMSPLIT_3G_OPT 1476 default 0x80000000 if VMSPLIT_2G 1477 default 0x78000000 if VMSPLIT_2G_OPT 1478 default 0x40000000 if VMSPLIT_1G 1479 default 0xC0000000 1480 depends on X86_32 1481 1482config HIGHMEM 1483 def_bool y 1484 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1485 1486config X86_PAE 1487 bool "PAE (Physical Address Extension) Support" 1488 depends on X86_32 && !HIGHMEM4G 1489 select PHYS_ADDR_T_64BIT 1490 select SWIOTLB 1491 help 1492 PAE is required for NX support, and furthermore enables 1493 larger swapspace support for non-overcommit purposes. It 1494 has the cost of more pagetable lookup overhead, and also 1495 consumes more pagetable space per process. 1496 1497config X86_5LEVEL 1498 bool "Enable 5-level page tables support" 1499 default y 1500 select DYNAMIC_MEMORY_LAYOUT 1501 select SPARSEMEM_VMEMMAP 1502 depends on X86_64 1503 help 1504 5-level paging enables access to larger address space: 1505 upto 128 PiB of virtual address space and 4 PiB of 1506 physical address space. 1507 1508 It will be supported by future Intel CPUs. 1509 1510 A kernel with the option enabled can be booted on machines that 1511 support 4- or 5-level paging. 1512 1513 See Documentation/x86/x86_64/5level-paging.rst for more 1514 information. 1515 1516 Say N if unsure. 1517 1518config X86_DIRECT_GBPAGES 1519 def_bool y 1520 depends on X86_64 1521 help 1522 Certain kernel features effectively disable kernel 1523 linear 1 GB mappings (even if the CPU otherwise 1524 supports them), so don't confuse the user by printing 1525 that we have them enabled. 1526 1527config X86_CPA_STATISTICS 1528 bool "Enable statistic for Change Page Attribute" 1529 depends on DEBUG_FS 1530 help 1531 Expose statistics about the Change Page Attribute mechanism, which 1532 helps to determine the effectiveness of preserving large and huge 1533 page mappings when mapping protections are changed. 1534 1535config X86_MEM_ENCRYPT 1536 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1537 select DYNAMIC_PHYSICAL_MASK 1538 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS 1539 def_bool n 1540 1541config AMD_MEM_ENCRYPT 1542 bool "AMD Secure Memory Encryption (SME) support" 1543 depends on X86_64 && CPU_SUP_AMD 1544 select DMA_COHERENT_POOL 1545 select ARCH_USE_MEMREMAP_PROT 1546 select INSTRUCTION_DECODER 1547 select ARCH_HAS_CC_PLATFORM 1548 select X86_MEM_ENCRYPT 1549 help 1550 Say yes to enable support for the encryption of system memory. 1551 This requires an AMD processor that supports Secure Memory 1552 Encryption (SME). 1553 1554config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1555 bool "Activate AMD Secure Memory Encryption (SME) by default" 1556 depends on AMD_MEM_ENCRYPT 1557 help 1558 Say yes to have system memory encrypted by default if running on 1559 an AMD processor that supports Secure Memory Encryption (SME). 1560 1561 If set to Y, then the encryption of system memory can be 1562 deactivated with the mem_encrypt=off command line option. 1563 1564 If set to N, then the encryption of system memory can be 1565 activated with the mem_encrypt=on command line option. 1566 1567# Common NUMA Features 1568config NUMA 1569 bool "NUMA Memory Allocation and Scheduler Support" 1570 depends on SMP 1571 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1572 default y if X86_BIGSMP 1573 select USE_PERCPU_NUMA_NODE_ID 1574 help 1575 Enable NUMA (Non-Uniform Memory Access) support. 1576 1577 The kernel will try to allocate memory used by a CPU on the 1578 local memory controller of the CPU and add some more 1579 NUMA awareness to the kernel. 1580 1581 For 64-bit this is recommended if the system is Intel Core i7 1582 (or later), AMD Opteron, or EM64T NUMA. 1583 1584 For 32-bit this is only needed if you boot a 32-bit 1585 kernel on a 64-bit NUMA platform. 1586 1587 Otherwise, you should say N. 1588 1589config AMD_NUMA 1590 def_bool y 1591 prompt "Old style AMD Opteron NUMA detection" 1592 depends on X86_64 && NUMA && PCI 1593 help 1594 Enable AMD NUMA node topology detection. You should say Y here if 1595 you have a multi processor AMD system. This uses an old method to 1596 read the NUMA configuration directly from the builtin Northbridge 1597 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1598 which also takes priority if both are compiled in. 1599 1600config X86_64_ACPI_NUMA 1601 def_bool y 1602 prompt "ACPI NUMA detection" 1603 depends on X86_64 && NUMA && ACPI && PCI 1604 select ACPI_NUMA 1605 help 1606 Enable ACPI SRAT based node topology detection. 1607 1608config NUMA_EMU 1609 bool "NUMA emulation" 1610 depends on NUMA 1611 help 1612 Enable NUMA emulation. A flat machine will be split 1613 into virtual nodes when booted with "numa=fake=N", where N is the 1614 number of nodes. This is only useful for debugging. 1615 1616config NODES_SHIFT 1617 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1618 range 1 10 1619 default "10" if MAXSMP 1620 default "6" if X86_64 1621 default "3" 1622 depends on NUMA 1623 help 1624 Specify the maximum number of NUMA Nodes available on the target 1625 system. Increases memory reserved to accommodate various tables. 1626 1627config ARCH_FLATMEM_ENABLE 1628 def_bool y 1629 depends on X86_32 && !NUMA 1630 1631config ARCH_SPARSEMEM_ENABLE 1632 def_bool y 1633 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1634 select SPARSEMEM_STATIC if X86_32 1635 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1636 1637config ARCH_SPARSEMEM_DEFAULT 1638 def_bool X86_64 || (NUMA && X86_32) 1639 1640config ARCH_SELECT_MEMORY_MODEL 1641 def_bool y 1642 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1643 1644config ARCH_MEMORY_PROBE 1645 bool "Enable sysfs memory/probe interface" 1646 depends on MEMORY_HOTPLUG 1647 help 1648 This option enables a sysfs memory/probe interface for testing. 1649 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1650 If you are unsure how to answer this question, answer N. 1651 1652config ARCH_PROC_KCORE_TEXT 1653 def_bool y 1654 depends on X86_64 && PROC_KCORE 1655 1656config ILLEGAL_POINTER_VALUE 1657 hex 1658 default 0 if X86_32 1659 default 0xdead000000000000 if X86_64 1660 1661config X86_PMEM_LEGACY_DEVICE 1662 bool 1663 1664config X86_PMEM_LEGACY 1665 tristate "Support non-standard NVDIMMs and ADR protected memory" 1666 depends on PHYS_ADDR_T_64BIT 1667 depends on BLK_DEV 1668 select X86_PMEM_LEGACY_DEVICE 1669 select NUMA_KEEP_MEMINFO if NUMA 1670 select LIBNVDIMM 1671 help 1672 Treat memory marked using the non-standard e820 type of 12 as used 1673 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1674 The kernel will offer these regions to the 'pmem' driver so 1675 they can be used for persistent storage. 1676 1677 Say Y if unsure. 1678 1679config HIGHPTE 1680 bool "Allocate 3rd-level pagetables from highmem" 1681 depends on HIGHMEM 1682 help 1683 The VM uses one page table entry for each page of physical memory. 1684 For systems with a lot of RAM, this can be wasteful of precious 1685 low memory. Setting this option will put user-space page table 1686 entries in high memory. 1687 1688config X86_CHECK_BIOS_CORRUPTION 1689 bool "Check for low memory corruption" 1690 help 1691 Periodically check for memory corruption in low memory, which 1692 is suspected to be caused by BIOS. Even when enabled in the 1693 configuration, it is disabled at runtime. Enable it by 1694 setting "memory_corruption_check=1" on the kernel command 1695 line. By default it scans the low 64k of memory every 60 1696 seconds; see the memory_corruption_check_size and 1697 memory_corruption_check_period parameters in 1698 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1699 1700 When enabled with the default parameters, this option has 1701 almost no overhead, as it reserves a relatively small amount 1702 of memory and scans it infrequently. It both detects corruption 1703 and prevents it from affecting the running system. 1704 1705 It is, however, intended as a diagnostic tool; if repeatable 1706 BIOS-originated corruption always affects the same memory, 1707 you can use memmap= to prevent the kernel from using that 1708 memory. 1709 1710config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1711 bool "Set the default setting of memory_corruption_check" 1712 depends on X86_CHECK_BIOS_CORRUPTION 1713 default y 1714 help 1715 Set whether the default state of memory_corruption_check is 1716 on or off. 1717 1718config MATH_EMULATION 1719 bool 1720 depends on MODIFY_LDT_SYSCALL 1721 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1722 help 1723 Linux can emulate a math coprocessor (used for floating point 1724 operations) if you don't have one. 486DX and Pentium processors have 1725 a math coprocessor built in, 486SX and 386 do not, unless you added 1726 a 487DX or 387, respectively. (The messages during boot time can 1727 give you some hints here ["man dmesg"].) Everyone needs either a 1728 coprocessor or this emulation. 1729 1730 If you don't have a math coprocessor, you need to say Y here; if you 1731 say Y here even though you have a coprocessor, the coprocessor will 1732 be used nevertheless. (This behavior can be changed with the kernel 1733 command line option "no387", which comes handy if your coprocessor 1734 is broken. Try "man bootparam" or see the documentation of your boot 1735 loader (lilo or loadlin) about how to pass options to the kernel at 1736 boot time.) This means that it is a good idea to say Y here if you 1737 intend to use this kernel on different machines. 1738 1739 More information about the internals of the Linux math coprocessor 1740 emulation can be found in <file:arch/x86/math-emu/README>. 1741 1742 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1743 kernel, it won't hurt. 1744 1745config MTRR 1746 def_bool y 1747 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1748 help 1749 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1750 the Memory Type Range Registers (MTRRs) may be used to control 1751 processor access to memory ranges. This is most useful if you have 1752 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1753 allows bus write transfers to be combined into a larger transfer 1754 before bursting over the PCI/AGP bus. This can increase performance 1755 of image write operations 2.5 times or more. Saying Y here creates a 1756 /proc/mtrr file which may be used to manipulate your processor's 1757 MTRRs. Typically the X server should use this. 1758 1759 This code has a reasonably generic interface so that similar 1760 control registers on other processors can be easily supported 1761 as well: 1762 1763 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1764 Registers (ARRs) which provide a similar functionality to MTRRs. For 1765 these, the ARRs are used to emulate the MTRRs. 1766 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1767 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1768 write-combining. All of these processors are supported by this code 1769 and it makes sense to say Y here if you have one of them. 1770 1771 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1772 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1773 can lead to all sorts of problems, so it's good to say Y here. 1774 1775 You can safely say Y even if your machine doesn't have MTRRs, you'll 1776 just add about 9 KB to your kernel. 1777 1778 See <file:Documentation/x86/mtrr.rst> for more information. 1779 1780config MTRR_SANITIZER 1781 def_bool y 1782 prompt "MTRR cleanup support" 1783 depends on MTRR 1784 help 1785 Convert MTRR layout from continuous to discrete, so X drivers can 1786 add writeback entries. 1787 1788 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1789 The largest mtrr entry size for a continuous block can be set with 1790 mtrr_chunk_size. 1791 1792 If unsure, say Y. 1793 1794config MTRR_SANITIZER_ENABLE_DEFAULT 1795 int "MTRR cleanup enable value (0-1)" 1796 range 0 1 1797 default "0" 1798 depends on MTRR_SANITIZER 1799 help 1800 Enable mtrr cleanup default value 1801 1802config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1803 int "MTRR cleanup spare reg num (0-7)" 1804 range 0 7 1805 default "1" 1806 depends on MTRR_SANITIZER 1807 help 1808 mtrr cleanup spare entries default, it can be changed via 1809 mtrr_spare_reg_nr=N on the kernel command line. 1810 1811config X86_PAT 1812 def_bool y 1813 prompt "x86 PAT support" if EXPERT 1814 depends on MTRR 1815 help 1816 Use PAT attributes to setup page level cache control. 1817 1818 PATs are the modern equivalents of MTRRs and are much more 1819 flexible than MTRRs. 1820 1821 Say N here if you see bootup problems (boot crash, boot hang, 1822 spontaneous reboots) or a non-working video driver. 1823 1824 If unsure, say Y. 1825 1826config ARCH_USES_PG_UNCACHED 1827 def_bool y 1828 depends on X86_PAT 1829 1830config ARCH_RANDOM 1831 def_bool y 1832 prompt "x86 architectural random number generator" if EXPERT 1833 help 1834 Enable the x86 architectural RDRAND instruction 1835 (Intel Bull Mountain technology) to generate random numbers. 1836 If supported, this is a high bandwidth, cryptographically 1837 secure hardware random number generator. 1838 1839config X86_UMIP 1840 def_bool y 1841 prompt "User Mode Instruction Prevention" if EXPERT 1842 help 1843 User Mode Instruction Prevention (UMIP) is a security feature in 1844 some x86 processors. If enabled, a general protection fault is 1845 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1846 executed in user mode. These instructions unnecessarily expose 1847 information about the hardware state. 1848 1849 The vast majority of applications do not use these instructions. 1850 For the very few that do, software emulation is provided in 1851 specific cases in protected and virtual-8086 modes. Emulated 1852 results are dummy. 1853 1854config CC_HAS_IBT 1855 # GCC >= 9 and binutils >= 2.29 1856 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1857 # Clang/LLVM >= 14 1858 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1859 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1860 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1861 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1862 $(as-instr,endbr64) 1863 1864config X86_KERNEL_IBT 1865 prompt "Indirect Branch Tracking" 1866 bool 1867 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1868 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1869 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1870 select OBJTOOL 1871 help 1872 Build the kernel with support for Indirect Branch Tracking, a 1873 hardware support course-grain forward-edge Control Flow Integrity 1874 protection. It enforces that all indirect calls must land on 1875 an ENDBR instruction, as such, the compiler will instrument the 1876 code with them to make this happen. 1877 1878 In addition to building the kernel with IBT, seal all functions that 1879 are not indirect call targets, avoiding them ever becoming one. 1880 1881 This requires LTO like objtool runs and will slow down the build. It 1882 does significantly reduce the number of ENDBR instructions in the 1883 kernel image. 1884 1885config X86_INTEL_MEMORY_PROTECTION_KEYS 1886 prompt "Memory Protection Keys" 1887 def_bool y 1888 # Note: only available in 64-bit mode 1889 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1890 select ARCH_USES_HIGH_VMA_FLAGS 1891 select ARCH_HAS_PKEYS 1892 help 1893 Memory Protection Keys provides a mechanism for enforcing 1894 page-based protections, but without requiring modification of the 1895 page tables when an application changes protection domains. 1896 1897 For details, see Documentation/core-api/protection-keys.rst 1898 1899 If unsure, say y. 1900 1901choice 1902 prompt "TSX enable mode" 1903 depends on CPU_SUP_INTEL 1904 default X86_INTEL_TSX_MODE_OFF 1905 help 1906 Intel's TSX (Transactional Synchronization Extensions) feature 1907 allows to optimize locking protocols through lock elision which 1908 can lead to a noticeable performance boost. 1909 1910 On the other hand it has been shown that TSX can be exploited 1911 to form side channel attacks (e.g. TAA) and chances are there 1912 will be more of those attacks discovered in the future. 1913 1914 Therefore TSX is not enabled by default (aka tsx=off). An admin 1915 might override this decision by tsx=on the command line parameter. 1916 Even with TSX enabled, the kernel will attempt to enable the best 1917 possible TAA mitigation setting depending on the microcode available 1918 for the particular machine. 1919 1920 This option allows to set the default tsx mode between tsx=on, =off 1921 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1922 details. 1923 1924 Say off if not sure, auto if TSX is in use but it should be used on safe 1925 platforms or on if TSX is in use and the security aspect of tsx is not 1926 relevant. 1927 1928config X86_INTEL_TSX_MODE_OFF 1929 bool "off" 1930 help 1931 TSX is disabled if possible - equals to tsx=off command line parameter. 1932 1933config X86_INTEL_TSX_MODE_ON 1934 bool "on" 1935 help 1936 TSX is always enabled on TSX capable HW - equals the tsx=on command 1937 line parameter. 1938 1939config X86_INTEL_TSX_MODE_AUTO 1940 bool "auto" 1941 help 1942 TSX is enabled on TSX capable HW that is believed to be safe against 1943 side channel attacks- equals the tsx=auto command line parameter. 1944endchoice 1945 1946config X86_SGX 1947 bool "Software Guard eXtensions (SGX)" 1948 depends on X86_64 && CPU_SUP_INTEL 1949 depends on CRYPTO=y 1950 depends on CRYPTO_SHA256=y 1951 select SRCU 1952 select MMU_NOTIFIER 1953 select NUMA_KEEP_MEMINFO if NUMA 1954 select XARRAY_MULTI 1955 help 1956 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1957 that can be used by applications to set aside private regions of code 1958 and data, referred to as enclaves. An enclave's private memory can 1959 only be accessed by code running within the enclave. Accesses from 1960 outside the enclave, including other enclaves, are disallowed by 1961 hardware. 1962 1963 If unsure, say N. 1964 1965config EFI 1966 bool "EFI runtime service support" 1967 depends on ACPI 1968 select UCS2_STRING 1969 select EFI_RUNTIME_WRAPPERS 1970 select ARCH_USE_MEMREMAP_PROT 1971 help 1972 This enables the kernel to use EFI runtime services that are 1973 available (such as the EFI variable services). 1974 1975 This option is only useful on systems that have EFI firmware. 1976 In addition, you should use the latest ELILO loader available 1977 at <http://elilo.sourceforge.net> in order to take advantage 1978 of EFI runtime services. However, even with this option, the 1979 resultant kernel should continue to boot on existing non-EFI 1980 platforms. 1981 1982config EFI_STUB 1983 bool "EFI stub support" 1984 depends on EFI 1985 depends on $(cc-option,-mabi=ms) || X86_32 1986 select RELOCATABLE 1987 help 1988 This kernel feature allows a bzImage to be loaded directly 1989 by EFI firmware without the use of a bootloader. 1990 1991 See Documentation/admin-guide/efi-stub.rst for more information. 1992 1993config EFI_MIXED 1994 bool "EFI mixed-mode support" 1995 depends on EFI_STUB && X86_64 1996 help 1997 Enabling this feature allows a 64-bit kernel to be booted 1998 on a 32-bit firmware, provided that your CPU supports 64-bit 1999 mode. 2000 2001 Note that it is not possible to boot a mixed-mode enabled 2002 kernel via the EFI boot stub - a bootloader that supports 2003 the EFI handover protocol must be used. 2004 2005 If unsure, say N. 2006 2007source "kernel/Kconfig.hz" 2008 2009config KEXEC 2010 bool "kexec system call" 2011 select KEXEC_CORE 2012 help 2013 kexec is a system call that implements the ability to shutdown your 2014 current kernel, and to start another kernel. It is like a reboot 2015 but it is independent of the system firmware. And like a reboot 2016 you can start any kernel with it, not just Linux. 2017 2018 The name comes from the similarity to the exec system call. 2019 2020 It is an ongoing process to be certain the hardware in a machine 2021 is properly shutdown, so do not be surprised if this code does not 2022 initially work for you. As of this writing the exact hardware 2023 interface is strongly in flux, so no good recommendation can be 2024 made. 2025 2026config KEXEC_FILE 2027 bool "kexec file based system call" 2028 select KEXEC_CORE 2029 select BUILD_BIN2C 2030 depends on X86_64 2031 depends on CRYPTO=y 2032 depends on CRYPTO_SHA256=y 2033 help 2034 This is new version of kexec system call. This system call is 2035 file based and takes file descriptors as system call argument 2036 for kernel and initramfs as opposed to list of segments as 2037 accepted by previous system call. 2038 2039config ARCH_HAS_KEXEC_PURGATORY 2040 def_bool KEXEC_FILE 2041 2042config KEXEC_SIG 2043 bool "Verify kernel signature during kexec_file_load() syscall" 2044 depends on KEXEC_FILE 2045 help 2046 2047 This option makes the kexec_file_load() syscall check for a valid 2048 signature of the kernel image. The image can still be loaded without 2049 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2050 there's a signature that we can check, then it must be valid. 2051 2052 In addition to this option, you need to enable signature 2053 verification for the corresponding kernel image type being 2054 loaded in order for this to work. 2055 2056config KEXEC_SIG_FORCE 2057 bool "Require a valid signature in kexec_file_load() syscall" 2058 depends on KEXEC_SIG 2059 help 2060 This option makes kernel signature verification mandatory for 2061 the kexec_file_load() syscall. 2062 2063config KEXEC_BZIMAGE_VERIFY_SIG 2064 bool "Enable bzImage signature verification support" 2065 depends on KEXEC_SIG 2066 depends on SIGNED_PE_FILE_VERIFICATION 2067 select SYSTEM_TRUSTED_KEYRING 2068 help 2069 Enable bzImage signature verification support. 2070 2071config CRASH_DUMP 2072 bool "kernel crash dumps" 2073 depends on X86_64 || (X86_32 && HIGHMEM) 2074 help 2075 Generate crash dump after being started by kexec. 2076 This should be normally only set in special crash dump kernels 2077 which are loaded in the main kernel with kexec-tools into 2078 a specially reserved region and then later executed after 2079 a crash by kdump/kexec. The crash dump kernel must be compiled 2080 to a memory address not used by the main kernel or BIOS using 2081 PHYSICAL_START, or it must be built as a relocatable image 2082 (CONFIG_RELOCATABLE=y). 2083 For more details see Documentation/admin-guide/kdump/kdump.rst 2084 2085config KEXEC_JUMP 2086 bool "kexec jump" 2087 depends on KEXEC && HIBERNATION 2088 help 2089 Jump between original kernel and kexeced kernel and invoke 2090 code in physical address mode via KEXEC 2091 2092config PHYSICAL_START 2093 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2094 default "0x1000000" 2095 help 2096 This gives the physical address where the kernel is loaded. 2097 2098 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2099 bzImage will decompress itself to above physical address and 2100 run from there. Otherwise, bzImage will run from the address where 2101 it has been loaded by the boot loader and will ignore above physical 2102 address. 2103 2104 In normal kdump cases one does not have to set/change this option 2105 as now bzImage can be compiled as a completely relocatable image 2106 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2107 address. This option is mainly useful for the folks who don't want 2108 to use a bzImage for capturing the crash dump and want to use a 2109 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2110 to be specifically compiled to run from a specific memory area 2111 (normally a reserved region) and this option comes handy. 2112 2113 So if you are using bzImage for capturing the crash dump, 2114 leave the value here unchanged to 0x1000000 and set 2115 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2116 for capturing the crash dump change this value to start of 2117 the reserved region. In other words, it can be set based on 2118 the "X" value as specified in the "crashkernel=YM@XM" 2119 command line boot parameter passed to the panic-ed 2120 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2121 for more details about crash dumps. 2122 2123 Usage of bzImage for capturing the crash dump is recommended as 2124 one does not have to build two kernels. Same kernel can be used 2125 as production kernel and capture kernel. Above option should have 2126 gone away after relocatable bzImage support is introduced. But it 2127 is present because there are users out there who continue to use 2128 vmlinux for dump capture. This option should go away down the 2129 line. 2130 2131 Don't change this unless you know what you are doing. 2132 2133config RELOCATABLE 2134 bool "Build a relocatable kernel" 2135 default y 2136 help 2137 This builds a kernel image that retains relocation information 2138 so it can be loaded someplace besides the default 1MB. 2139 The relocations tend to make the kernel binary about 10% larger, 2140 but are discarded at runtime. 2141 2142 One use is for the kexec on panic case where the recovery kernel 2143 must live at a different physical address than the primary 2144 kernel. 2145 2146 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2147 it has been loaded at and the compile time physical address 2148 (CONFIG_PHYSICAL_START) is used as the minimum location. 2149 2150config RANDOMIZE_BASE 2151 bool "Randomize the address of the kernel image (KASLR)" 2152 depends on RELOCATABLE 2153 default y 2154 help 2155 In support of Kernel Address Space Layout Randomization (KASLR), 2156 this randomizes the physical address at which the kernel image 2157 is decompressed and the virtual address where the kernel 2158 image is mapped, as a security feature that deters exploit 2159 attempts relying on knowledge of the location of kernel 2160 code internals. 2161 2162 On 64-bit, the kernel physical and virtual addresses are 2163 randomized separately. The physical address will be anywhere 2164 between 16MB and the top of physical memory (up to 64TB). The 2165 virtual address will be randomized from 16MB up to 1GB (9 bits 2166 of entropy). Note that this also reduces the memory space 2167 available to kernel modules from 1.5GB to 1GB. 2168 2169 On 32-bit, the kernel physical and virtual addresses are 2170 randomized together. They will be randomized from 16MB up to 2171 512MB (8 bits of entropy). 2172 2173 Entropy is generated using the RDRAND instruction if it is 2174 supported. If RDTSC is supported, its value is mixed into 2175 the entropy pool as well. If neither RDRAND nor RDTSC are 2176 supported, then entropy is read from the i8254 timer. The 2177 usable entropy is limited by the kernel being built using 2178 2GB addressing, and that PHYSICAL_ALIGN must be at a 2179 minimum of 2MB. As a result, only 10 bits of entropy are 2180 theoretically possible, but the implementations are further 2181 limited due to memory layouts. 2182 2183 If unsure, say Y. 2184 2185# Relocation on x86 needs some additional build support 2186config X86_NEED_RELOCS 2187 def_bool y 2188 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2189 2190config PHYSICAL_ALIGN 2191 hex "Alignment value to which kernel should be aligned" 2192 default "0x200000" 2193 range 0x2000 0x1000000 if X86_32 2194 range 0x200000 0x1000000 if X86_64 2195 help 2196 This value puts the alignment restrictions on physical address 2197 where kernel is loaded and run from. Kernel is compiled for an 2198 address which meets above alignment restriction. 2199 2200 If bootloader loads the kernel at a non-aligned address and 2201 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2202 address aligned to above value and run from there. 2203 2204 If bootloader loads the kernel at a non-aligned address and 2205 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2206 load address and decompress itself to the address it has been 2207 compiled for and run from there. The address for which kernel is 2208 compiled already meets above alignment restrictions. Hence the 2209 end result is that kernel runs from a physical address meeting 2210 above alignment restrictions. 2211 2212 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2213 this value must be a multiple of 0x200000. 2214 2215 Don't change this unless you know what you are doing. 2216 2217config DYNAMIC_MEMORY_LAYOUT 2218 bool 2219 help 2220 This option makes base addresses of vmalloc and vmemmap as well as 2221 __PAGE_OFFSET movable during boot. 2222 2223config RANDOMIZE_MEMORY 2224 bool "Randomize the kernel memory sections" 2225 depends on X86_64 2226 depends on RANDOMIZE_BASE 2227 select DYNAMIC_MEMORY_LAYOUT 2228 default RANDOMIZE_BASE 2229 help 2230 Randomizes the base virtual address of kernel memory sections 2231 (physical memory mapping, vmalloc & vmemmap). This security feature 2232 makes exploits relying on predictable memory locations less reliable. 2233 2234 The order of allocations remains unchanged. Entropy is generated in 2235 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2236 configuration have in average 30,000 different possible virtual 2237 addresses for each memory section. 2238 2239 If unsure, say Y. 2240 2241config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2242 hex "Physical memory mapping padding" if EXPERT 2243 depends on RANDOMIZE_MEMORY 2244 default "0xa" if MEMORY_HOTPLUG 2245 default "0x0" 2246 range 0x1 0x40 if MEMORY_HOTPLUG 2247 range 0x0 0x40 2248 help 2249 Define the padding in terabytes added to the existing physical 2250 memory size during kernel memory randomization. It is useful 2251 for memory hotplug support but reduces the entropy available for 2252 address randomization. 2253 2254 If unsure, leave at the default value. 2255 2256config HOTPLUG_CPU 2257 def_bool y 2258 depends on SMP 2259 2260config BOOTPARAM_HOTPLUG_CPU0 2261 bool "Set default setting of cpu0_hotpluggable" 2262 depends on HOTPLUG_CPU 2263 help 2264 Set whether default state of cpu0_hotpluggable is on or off. 2265 2266 Say Y here to enable CPU0 hotplug by default. If this switch 2267 is turned on, there is no need to give cpu0_hotplug kernel 2268 parameter and the CPU0 hotplug feature is enabled by default. 2269 2270 Please note: there are two known CPU0 dependencies if you want 2271 to enable the CPU0 hotplug feature either by this switch or by 2272 cpu0_hotplug kernel parameter. 2273 2274 First, resume from hibernate or suspend always starts from CPU0. 2275 So hibernate and suspend are prevented if CPU0 is offline. 2276 2277 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2278 offline if any interrupt can not migrate out of CPU0. There may 2279 be other CPU0 dependencies. 2280 2281 Please make sure the dependencies are under your control before 2282 you enable this feature. 2283 2284 Say N if you don't want to enable CPU0 hotplug feature by default. 2285 You still can enable the CPU0 hotplug feature at boot by kernel 2286 parameter cpu0_hotplug. 2287 2288config DEBUG_HOTPLUG_CPU0 2289 def_bool n 2290 prompt "Debug CPU0 hotplug" 2291 depends on HOTPLUG_CPU 2292 help 2293 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2294 soon as possible and boots up userspace with CPU0 offlined. User 2295 can online CPU0 back after boot time. 2296 2297 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2298 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2299 compilation or giving cpu0_hotplug kernel parameter at boot. 2300 2301 If unsure, say N. 2302 2303config COMPAT_VDSO 2304 def_bool n 2305 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2306 depends on COMPAT_32 2307 help 2308 Certain buggy versions of glibc will crash if they are 2309 presented with a 32-bit vDSO that is not mapped at the address 2310 indicated in its segment table. 2311 2312 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2313 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2314 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2315 the only released version with the bug, but OpenSUSE 9 2316 contains a buggy "glibc 2.3.2". 2317 2318 The symptom of the bug is that everything crashes on startup, saying: 2319 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2320 2321 Saying Y here changes the default value of the vdso32 boot 2322 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2323 This works around the glibc bug but hurts performance. 2324 2325 If unsure, say N: if you are compiling your own kernel, you 2326 are unlikely to be using a buggy version of glibc. 2327 2328choice 2329 prompt "vsyscall table for legacy applications" 2330 depends on X86_64 2331 default LEGACY_VSYSCALL_XONLY 2332 help 2333 Legacy user code that does not know how to find the vDSO expects 2334 to be able to issue three syscalls by calling fixed addresses in 2335 kernel space. Since this location is not randomized with ASLR, 2336 it can be used to assist security vulnerability exploitation. 2337 2338 This setting can be changed at boot time via the kernel command 2339 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2340 is deprecated and can only be enabled using the kernel command 2341 line. 2342 2343 On a system with recent enough glibc (2.14 or newer) and no 2344 static binaries, you can say None without a performance penalty 2345 to improve security. 2346 2347 If unsure, select "Emulate execution only". 2348 2349 config LEGACY_VSYSCALL_XONLY 2350 bool "Emulate execution only" 2351 help 2352 The kernel traps and emulates calls into the fixed vsyscall 2353 address mapping and does not allow reads. This 2354 configuration is recommended when userspace might use the 2355 legacy vsyscall area but support for legacy binary 2356 instrumentation of legacy code is not needed. It mitigates 2357 certain uses of the vsyscall area as an ASLR-bypassing 2358 buffer. 2359 2360 config LEGACY_VSYSCALL_NONE 2361 bool "None" 2362 help 2363 There will be no vsyscall mapping at all. This will 2364 eliminate any risk of ASLR bypass due to the vsyscall 2365 fixed address mapping. Attempts to use the vsyscalls 2366 will be reported to dmesg, so that either old or 2367 malicious userspace programs can be identified. 2368 2369endchoice 2370 2371config CMDLINE_BOOL 2372 bool "Built-in kernel command line" 2373 help 2374 Allow for specifying boot arguments to the kernel at 2375 build time. On some systems (e.g. embedded ones), it is 2376 necessary or convenient to provide some or all of the 2377 kernel boot arguments with the kernel itself (that is, 2378 to not rely on the boot loader to provide them.) 2379 2380 To compile command line arguments into the kernel, 2381 set this option to 'Y', then fill in the 2382 boot arguments in CONFIG_CMDLINE. 2383 2384 Systems with fully functional boot loaders (i.e. non-embedded) 2385 should leave this option set to 'N'. 2386 2387config CMDLINE 2388 string "Built-in kernel command string" 2389 depends on CMDLINE_BOOL 2390 default "" 2391 help 2392 Enter arguments here that should be compiled into the kernel 2393 image and used at boot time. If the boot loader provides a 2394 command line at boot time, it is appended to this string to 2395 form the full kernel command line, when the system boots. 2396 2397 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2398 change this behavior. 2399 2400 In most cases, the command line (whether built-in or provided 2401 by the boot loader) should specify the device for the root 2402 file system. 2403 2404config CMDLINE_OVERRIDE 2405 bool "Built-in command line overrides boot loader arguments" 2406 depends on CMDLINE_BOOL && CMDLINE != "" 2407 help 2408 Set this option to 'Y' to have the kernel ignore the boot loader 2409 command line, and use ONLY the built-in command line. 2410 2411 This is used to work around broken boot loaders. This should 2412 be set to 'N' under normal conditions. 2413 2414config MODIFY_LDT_SYSCALL 2415 bool "Enable the LDT (local descriptor table)" if EXPERT 2416 default y 2417 help 2418 Linux can allow user programs to install a per-process x86 2419 Local Descriptor Table (LDT) using the modify_ldt(2) system 2420 call. This is required to run 16-bit or segmented code such as 2421 DOSEMU or some Wine programs. It is also used by some very old 2422 threading libraries. 2423 2424 Enabling this feature adds a small amount of overhead to 2425 context switches and increases the low-level kernel attack 2426 surface. Disabling it removes the modify_ldt(2) system call. 2427 2428 Saying 'N' here may make sense for embedded or server kernels. 2429 2430config STRICT_SIGALTSTACK_SIZE 2431 bool "Enforce strict size checking for sigaltstack" 2432 depends on DYNAMIC_SIGFRAME 2433 help 2434 For historical reasons MINSIGSTKSZ is a constant which became 2435 already too small with AVX512 support. Add a mechanism to 2436 enforce strict checking of the sigaltstack size against the 2437 real size of the FPU frame. This option enables the check 2438 by default. It can also be controlled via the kernel command 2439 line option 'strict_sas_size' independent of this config 2440 switch. Enabling it might break existing applications which 2441 allocate a too small sigaltstack but 'work' because they 2442 never get a signal delivered. 2443 2444 Say 'N' unless you want to really enforce this check. 2445 2446source "kernel/livepatch/Kconfig" 2447 2448endmenu 2449 2450config ARCH_HAS_ADD_PAGES 2451 def_bool y 2452 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2453 2454config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2455 def_bool y 2456 2457menu "Power management and ACPI options" 2458 2459config ARCH_HIBERNATION_HEADER 2460 def_bool y 2461 depends on HIBERNATION 2462 2463source "kernel/power/Kconfig" 2464 2465source "drivers/acpi/Kconfig" 2466 2467config X86_APM_BOOT 2468 def_bool y 2469 depends on APM 2470 2471menuconfig APM 2472 tristate "APM (Advanced Power Management) BIOS support" 2473 depends on X86_32 && PM_SLEEP 2474 help 2475 APM is a BIOS specification for saving power using several different 2476 techniques. This is mostly useful for battery powered laptops with 2477 APM compliant BIOSes. If you say Y here, the system time will be 2478 reset after a RESUME operation, the /proc/apm device will provide 2479 battery status information, and user-space programs will receive 2480 notification of APM "events" (e.g. battery status change). 2481 2482 If you select "Y" here, you can disable actual use of the APM 2483 BIOS by passing the "apm=off" option to the kernel at boot time. 2484 2485 Note that the APM support is almost completely disabled for 2486 machines with more than one CPU. 2487 2488 In order to use APM, you will need supporting software. For location 2489 and more information, read <file:Documentation/power/apm-acpi.rst> 2490 and the Battery Powered Linux mini-HOWTO, available from 2491 <http://www.tldp.org/docs.html#howto>. 2492 2493 This driver does not spin down disk drives (see the hdparm(8) 2494 manpage ("man 8 hdparm") for that), and it doesn't turn off 2495 VESA-compliant "green" monitors. 2496 2497 This driver does not support the TI 4000M TravelMate and the ACER 2498 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2499 desktop machines also don't have compliant BIOSes, and this driver 2500 may cause those machines to panic during the boot phase. 2501 2502 Generally, if you don't have a battery in your machine, there isn't 2503 much point in using this driver and you should say N. If you get 2504 random kernel OOPSes or reboots that don't seem to be related to 2505 anything, try disabling/enabling this option (or disabling/enabling 2506 APM in your BIOS). 2507 2508 Some other things you should try when experiencing seemingly random, 2509 "weird" problems: 2510 2511 1) make sure that you have enough swap space and that it is 2512 enabled. 2513 2) pass the "no-hlt" option to the kernel 2514 3) switch on floating point emulation in the kernel and pass 2515 the "no387" option to the kernel 2516 4) pass the "floppy=nodma" option to the kernel 2517 5) pass the "mem=4M" option to the kernel (thereby disabling 2518 all but the first 4 MB of RAM) 2519 6) make sure that the CPU is not over clocked. 2520 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2521 8) disable the cache from your BIOS settings 2522 9) install a fan for the video card or exchange video RAM 2523 10) install a better fan for the CPU 2524 11) exchange RAM chips 2525 12) exchange the motherboard. 2526 2527 To compile this driver as a module, choose M here: the 2528 module will be called apm. 2529 2530if APM 2531 2532config APM_IGNORE_USER_SUSPEND 2533 bool "Ignore USER SUSPEND" 2534 help 2535 This option will ignore USER SUSPEND requests. On machines with a 2536 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2537 series notebooks, it is necessary to say Y because of a BIOS bug. 2538 2539config APM_DO_ENABLE 2540 bool "Enable PM at boot time" 2541 help 2542 Enable APM features at boot time. From page 36 of the APM BIOS 2543 specification: "When disabled, the APM BIOS does not automatically 2544 power manage devices, enter the Standby State, enter the Suspend 2545 State, or take power saving steps in response to CPU Idle calls." 2546 This driver will make CPU Idle calls when Linux is idle (unless this 2547 feature is turned off -- see "Do CPU IDLE calls", below). This 2548 should always save battery power, but more complicated APM features 2549 will be dependent on your BIOS implementation. You may need to turn 2550 this option off if your computer hangs at boot time when using APM 2551 support, or if it beeps continuously instead of suspending. Turn 2552 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2553 T400CDT. This is off by default since most machines do fine without 2554 this feature. 2555 2556config APM_CPU_IDLE 2557 depends on CPU_IDLE 2558 bool "Make CPU Idle calls when idle" 2559 help 2560 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2561 On some machines, this can activate improved power savings, such as 2562 a slowed CPU clock rate, when the machine is idle. These idle calls 2563 are made after the idle loop has run for some length of time (e.g., 2564 333 mS). On some machines, this will cause a hang at boot time or 2565 whenever the CPU becomes idle. (On machines with more than one CPU, 2566 this option does nothing.) 2567 2568config APM_DISPLAY_BLANK 2569 bool "Enable console blanking using APM" 2570 help 2571 Enable console blanking using the APM. Some laptops can use this to 2572 turn off the LCD backlight when the screen blanker of the Linux 2573 virtual console blanks the screen. Note that this is only used by 2574 the virtual console screen blanker, and won't turn off the backlight 2575 when using the X Window system. This also doesn't have anything to 2576 do with your VESA-compliant power-saving monitor. Further, this 2577 option doesn't work for all laptops -- it might not turn off your 2578 backlight at all, or it might print a lot of errors to the console, 2579 especially if you are using gpm. 2580 2581config APM_ALLOW_INTS 2582 bool "Allow interrupts during APM BIOS calls" 2583 help 2584 Normally we disable external interrupts while we are making calls to 2585 the APM BIOS as a measure to lessen the effects of a badly behaving 2586 BIOS implementation. The BIOS should reenable interrupts if it 2587 needs to. Unfortunately, some BIOSes do not -- especially those in 2588 many of the newer IBM Thinkpads. If you experience hangs when you 2589 suspend, try setting this to Y. Otherwise, say N. 2590 2591endif # APM 2592 2593source "drivers/cpufreq/Kconfig" 2594 2595source "drivers/cpuidle/Kconfig" 2596 2597source "drivers/idle/Kconfig" 2598 2599endmenu 2600 2601 2602menu "Bus options (PCI etc.)" 2603 2604choice 2605 prompt "PCI access mode" 2606 depends on X86_32 && PCI 2607 default PCI_GOANY 2608 help 2609 On PCI systems, the BIOS can be used to detect the PCI devices and 2610 determine their configuration. However, some old PCI motherboards 2611 have BIOS bugs and may crash if this is done. Also, some embedded 2612 PCI-based systems don't have any BIOS at all. Linux can also try to 2613 detect the PCI hardware directly without using the BIOS. 2614 2615 With this option, you can specify how Linux should detect the 2616 PCI devices. If you choose "BIOS", the BIOS will be used, 2617 if you choose "Direct", the BIOS won't be used, and if you 2618 choose "MMConfig", then PCI Express MMCONFIG will be used. 2619 If you choose "Any", the kernel will try MMCONFIG, then the 2620 direct access method and falls back to the BIOS if that doesn't 2621 work. If unsure, go with the default, which is "Any". 2622 2623config PCI_GOBIOS 2624 bool "BIOS" 2625 2626config PCI_GOMMCONFIG 2627 bool "MMConfig" 2628 2629config PCI_GODIRECT 2630 bool "Direct" 2631 2632config PCI_GOOLPC 2633 bool "OLPC XO-1" 2634 depends on OLPC 2635 2636config PCI_GOANY 2637 bool "Any" 2638 2639endchoice 2640 2641config PCI_BIOS 2642 def_bool y 2643 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2644 2645# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2646config PCI_DIRECT 2647 def_bool y 2648 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2649 2650config PCI_MMCONFIG 2651 bool "Support mmconfig PCI config space access" if X86_64 2652 default y 2653 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2654 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2655 2656config PCI_OLPC 2657 def_bool y 2658 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2659 2660config PCI_XEN 2661 def_bool y 2662 depends on PCI && XEN 2663 2664config MMCONF_FAM10H 2665 def_bool y 2666 depends on X86_64 && PCI_MMCONFIG && ACPI 2667 2668config PCI_CNB20LE_QUIRK 2669 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2670 depends on PCI 2671 help 2672 Read the PCI windows out of the CNB20LE host bridge. This allows 2673 PCI hotplug to work on systems with the CNB20LE chipset which do 2674 not have ACPI. 2675 2676 There's no public spec for this chipset, and this functionality 2677 is known to be incomplete. 2678 2679 You should say N unless you know you need this. 2680 2681config ISA_BUS 2682 bool "ISA bus support on modern systems" if EXPERT 2683 help 2684 Expose ISA bus device drivers and options available for selection and 2685 configuration. Enable this option if your target machine has an ISA 2686 bus. ISA is an older system, displaced by PCI and newer bus 2687 architectures -- if your target machine is modern, it probably does 2688 not have an ISA bus. 2689 2690 If unsure, say N. 2691 2692# x86_64 have no ISA slots, but can have ISA-style DMA. 2693config ISA_DMA_API 2694 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2695 default y 2696 help 2697 Enables ISA-style DMA support for devices requiring such controllers. 2698 If unsure, say Y. 2699 2700if X86_32 2701 2702config ISA 2703 bool "ISA support" 2704 help 2705 Find out whether you have ISA slots on your motherboard. ISA is the 2706 name of a bus system, i.e. the way the CPU talks to the other stuff 2707 inside your box. Other bus systems are PCI, EISA, MicroChannel 2708 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2709 newer boards don't support it. If you have ISA, say Y, otherwise N. 2710 2711config SCx200 2712 tristate "NatSemi SCx200 support" 2713 help 2714 This provides basic support for National Semiconductor's 2715 (now AMD's) Geode processors. The driver probes for the 2716 PCI-IDs of several on-chip devices, so its a good dependency 2717 for other scx200_* drivers. 2718 2719 If compiled as a module, the driver is named scx200. 2720 2721config SCx200HR_TIMER 2722 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2723 depends on SCx200 2724 default y 2725 help 2726 This driver provides a clocksource built upon the on-chip 2727 27MHz high-resolution timer. Its also a workaround for 2728 NSC Geode SC-1100's buggy TSC, which loses time when the 2729 processor goes idle (as is done by the scheduler). The 2730 other workaround is idle=poll boot option. 2731 2732config OLPC 2733 bool "One Laptop Per Child support" 2734 depends on !X86_PAE 2735 select GPIOLIB 2736 select OF 2737 select OF_PROMTREE 2738 select IRQ_DOMAIN 2739 select OLPC_EC 2740 help 2741 Add support for detecting the unique features of the OLPC 2742 XO hardware. 2743 2744config OLPC_XO1_PM 2745 bool "OLPC XO-1 Power Management" 2746 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2747 help 2748 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2749 2750config OLPC_XO1_RTC 2751 bool "OLPC XO-1 Real Time Clock" 2752 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2753 help 2754 Add support for the XO-1 real time clock, which can be used as a 2755 programmable wakeup source. 2756 2757config OLPC_XO1_SCI 2758 bool "OLPC XO-1 SCI extras" 2759 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2760 depends on INPUT=y 2761 select POWER_SUPPLY 2762 help 2763 Add support for SCI-based features of the OLPC XO-1 laptop: 2764 - EC-driven system wakeups 2765 - Power button 2766 - Ebook switch 2767 - Lid switch 2768 - AC adapter status updates 2769 - Battery status updates 2770 2771config OLPC_XO15_SCI 2772 bool "OLPC XO-1.5 SCI extras" 2773 depends on OLPC && ACPI 2774 select POWER_SUPPLY 2775 help 2776 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2777 - EC-driven system wakeups 2778 - AC adapter status updates 2779 - Battery status updates 2780 2781config ALIX 2782 bool "PCEngines ALIX System Support (LED setup)" 2783 select GPIOLIB 2784 help 2785 This option enables system support for the PCEngines ALIX. 2786 At present this just sets up LEDs for GPIO control on 2787 ALIX2/3/6 boards. However, other system specific setup should 2788 get added here. 2789 2790 Note: You must still enable the drivers for GPIO and LED support 2791 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2792 2793 Note: You have to set alix.force=1 for boards with Award BIOS. 2794 2795config NET5501 2796 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2797 select GPIOLIB 2798 help 2799 This option enables system support for the Soekris Engineering net5501. 2800 2801config GEOS 2802 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2803 select GPIOLIB 2804 depends on DMI 2805 help 2806 This option enables system support for the Traverse Technologies GEOS. 2807 2808config TS5500 2809 bool "Technologic Systems TS-5500 platform support" 2810 depends on MELAN 2811 select CHECK_SIGNATURE 2812 select NEW_LEDS 2813 select LEDS_CLASS 2814 help 2815 This option enables system support for the Technologic Systems TS-5500. 2816 2817endif # X86_32 2818 2819config AMD_NB 2820 def_bool y 2821 depends on CPU_SUP_AMD && PCI 2822 2823endmenu 2824 2825 2826menu "Binary Emulations" 2827 2828config IA32_EMULATION 2829 bool "IA32 Emulation" 2830 depends on X86_64 2831 select ARCH_WANT_OLD_COMPAT_IPC 2832 select BINFMT_ELF 2833 select COMPAT_OLD_SIGACTION 2834 help 2835 Include code to run legacy 32-bit programs under a 2836 64-bit kernel. You should likely turn this on, unless you're 2837 100% sure that you don't have any 32-bit programs left. 2838 2839config X86_X32_ABI 2840 bool "x32 ABI for 64-bit mode" 2841 depends on X86_64 2842 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2843 # compressed debug sections to x86_x32 properly: 2844 # https://github.com/ClangBuiltLinux/linux/issues/514 2845 # https://github.com/ClangBuiltLinux/linux/issues/1141 2846 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 2847 help 2848 Include code to run binaries for the x32 native 32-bit ABI 2849 for 64-bit processors. An x32 process gets access to the 2850 full 64-bit register file and wide data path while leaving 2851 pointers at 32 bits for smaller memory footprint. 2852 2853config COMPAT_32 2854 def_bool y 2855 depends on IA32_EMULATION || X86_32 2856 select HAVE_UID16 2857 select OLD_SIGSUSPEND3 2858 2859config COMPAT 2860 def_bool y 2861 depends on IA32_EMULATION || X86_X32_ABI 2862 2863if COMPAT 2864config COMPAT_FOR_U64_ALIGNMENT 2865 def_bool y 2866 2867config SYSVIPC_COMPAT 2868 def_bool y 2869 depends on SYSVIPC 2870endif 2871 2872endmenu 2873 2874 2875config HAVE_ATOMIC_IOMAP 2876 def_bool y 2877 depends on X86_32 2878 2879source "arch/x86/kvm/Kconfig" 2880 2881source "arch/x86/Kconfig.assembler" 2882