1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_USE_CMPXCHG_LOCKREF 31 select HAVE_ARCH_SOFT_DIRTY 32 select MODULES_USE_ELF_RELA 33 select NEED_DMA_MAP_STATE 34 select SWIOTLB 35 select ARCH_HAS_ELFCORE_COMPAT 36 select ZONE_DMA32 37 38config FORCE_DYNAMIC_FTRACE 39 def_bool y 40 depends on X86_32 41 depends on FUNCTION_TRACER 42 select DYNAMIC_FTRACE 43 help 44 We keep the static function tracing (!DYNAMIC_FTRACE) around 45 in order to test the non static function tracing in the 46 generic code, as other architectures still use it. But we 47 only need to keep it around for x86_64. No need to keep it 48 for x86_32. For x86_32, force DYNAMIC_FTRACE. 49# 50# Arch settings 51# 52# ( Note that options that are marked 'if X86_64' could in principle be 53# ported to 32-bit as well. ) 54# 55config X86 56 def_bool y 57 # 58 # Note: keep this list sorted alphabetically 59 # 60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 62 select ARCH_32BIT_OFF_T if X86_32 63 select ARCH_CLOCKSOURCE_INIT 64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 71 select ARCH_HAS_CACHE_LINE_SIZE 72 select ARCH_HAS_CURRENT_STACK_POINTER 73 select ARCH_HAS_DEBUG_VIRTUAL 74 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 75 select ARCH_HAS_DEVMEM_IS_ALLOWED 76 select ARCH_HAS_EARLY_DEBUG if KGDB 77 select ARCH_HAS_ELF_RANDOMIZE 78 select ARCH_HAS_FAST_MULTIPLIER 79 select ARCH_HAS_FORTIFY_SOURCE 80 select ARCH_HAS_GCOV_PROFILE_ALL 81 select ARCH_HAS_KCOV if X86_64 82 select ARCH_HAS_MEM_ENCRYPT 83 select ARCH_HAS_MEMBARRIER_SYNC_CORE 84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 85 select ARCH_HAS_PMEM_API if X86_64 86 select ARCH_HAS_PTE_DEVMAP if X86_64 87 select ARCH_HAS_PTE_SPECIAL 88 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 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_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64 125 select ARCH_WANT_LD_ORPHAN_WARN 126 select ARCH_WANTS_THP_SWAP if X86_64 127 select ARCH_HAS_PARANOID_L1D_FLUSH 128 select BUILDTIME_TABLE_SORT 129 select CLKEVT_I8253 130 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 131 select CLOCKSOURCE_WATCHDOG 132 select DCACHE_WORD_ACCESS 133 select DYNAMIC_SIGFRAME 134 select EDAC_ATOMIC_SCRUB 135 select EDAC_SUPPORT 136 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 137 select GENERIC_CLOCKEVENTS_MIN_ADJUST 138 select GENERIC_CMOS_UPDATE 139 select GENERIC_CPU_AUTOPROBE 140 select GENERIC_CPU_VULNERABILITIES 141 select GENERIC_EARLY_IOREMAP 142 select GENERIC_ENTRY 143 select GENERIC_IOMAP 144 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 145 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 146 select GENERIC_IRQ_MIGRATION if SMP 147 select GENERIC_IRQ_PROBE 148 select GENERIC_IRQ_RESERVATION_MODE 149 select GENERIC_IRQ_SHOW 150 select GENERIC_PENDING_IRQ if SMP 151 select GENERIC_PTDUMP 152 select GENERIC_SMP_IDLE_THREAD 153 select GENERIC_TIME_VSYSCALL 154 select GENERIC_GETTIMEOFDAY 155 select GENERIC_VDSO_TIME_NS 156 select GUP_GET_PTE_LOW_HIGH if X86_PAE 157 select HARDIRQS_SW_RESEND 158 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 159 select HAVE_ACPI_APEI if ACPI 160 select HAVE_ACPI_APEI_NMI if ACPI 161 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 162 select HAVE_ARCH_AUDITSYSCALL 163 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 164 select HAVE_ARCH_HUGE_VMALLOC if X86_64 165 select HAVE_ARCH_JUMP_LABEL 166 select HAVE_ARCH_JUMP_LABEL_RELATIVE 167 select HAVE_ARCH_KASAN if X86_64 168 select HAVE_ARCH_KASAN_VMALLOC if X86_64 169 select HAVE_ARCH_KFENCE 170 select HAVE_ARCH_KGDB 171 select HAVE_ARCH_MMAP_RND_BITS if MMU 172 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 173 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 174 select HAVE_ARCH_PREL32_RELOCATIONS 175 select HAVE_ARCH_SECCOMP_FILTER 176 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 177 select HAVE_ARCH_STACKLEAK 178 select HAVE_ARCH_TRACEHOOK 179 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 180 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 181 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 182 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 183 select HAVE_ARCH_VMAP_STACK if X86_64 184 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 185 select HAVE_ARCH_WITHIN_STACK_FRAMES 186 select HAVE_ASM_MODVERSIONS 187 select HAVE_CMPXCHG_DOUBLE 188 select HAVE_CMPXCHG_LOCAL 189 select HAVE_CONTEXT_TRACKING_USER if X86_64 190 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 191 select HAVE_C_RECORDMCOUNT 192 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 193 select HAVE_BUILDTIME_MCOUNT_SORT 194 select HAVE_DEBUG_KMEMLEAK 195 select HAVE_DMA_CONTIGUOUS 196 select HAVE_DYNAMIC_FTRACE 197 select HAVE_DYNAMIC_FTRACE_WITH_REGS 198 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 199 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 200 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 201 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 202 select HAVE_EBPF_JIT 203 select HAVE_EFFICIENT_UNALIGNED_ACCESS 204 select HAVE_EISA 205 select HAVE_EXIT_THREAD 206 select HAVE_FAST_GUP 207 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 208 select HAVE_FTRACE_MCOUNT_RECORD 209 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 210 select HAVE_FUNCTION_TRACER 211 select HAVE_GCC_PLUGINS 212 select HAVE_HW_BREAKPOINT 213 select HAVE_IOREMAP_PROT 214 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 215 select HAVE_IRQ_TIME_ACCOUNTING 216 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 217 select HAVE_KERNEL_BZIP2 218 select HAVE_KERNEL_GZIP 219 select HAVE_KERNEL_LZ4 220 select HAVE_KERNEL_LZMA 221 select HAVE_KERNEL_LZO 222 select HAVE_KERNEL_XZ 223 select HAVE_KERNEL_ZSTD 224 select HAVE_KPROBES 225 select HAVE_KPROBES_ON_FTRACE 226 select HAVE_FUNCTION_ERROR_INJECTION 227 select HAVE_KRETPROBES 228 select HAVE_RETHOOK 229 select HAVE_KVM 230 select HAVE_LIVEPATCH if X86_64 231 select HAVE_MIXED_BREAKPOINTS_REGS 232 select HAVE_MOD_ARCH_SPECIFIC 233 select HAVE_MOVE_PMD 234 select HAVE_MOVE_PUD 235 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 236 select HAVE_NMI 237 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 238 select HAVE_OBJTOOL if X86_64 239 select HAVE_OPTPROBES 240 select HAVE_PCSPKR_PLATFORM 241 select HAVE_PERF_EVENTS 242 select HAVE_PERF_EVENTS_NMI 243 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 244 select HAVE_PCI 245 select HAVE_PERF_REGS 246 select HAVE_PERF_USER_STACK_DUMP 247 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 248 select MMU_GATHER_MERGE_VMAS 249 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 250 select HAVE_REGS_AND_STACK_ACCESS_API 251 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 252 select HAVE_FUNCTION_ARG_ACCESS_API 253 select HAVE_SETUP_PER_CPU_AREA 254 select HAVE_SOFTIRQ_ON_OWN_STACK 255 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 256 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 257 select HAVE_STATIC_CALL 258 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 259 select HAVE_PREEMPT_DYNAMIC_CALL 260 select HAVE_RSEQ 261 select HAVE_SYSCALL_TRACEPOINTS 262 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 263 select HAVE_UNSTABLE_SCHED_CLOCK 264 select HAVE_USER_RETURN_NOTIFIER 265 select HAVE_GENERIC_VDSO 266 select HOTPLUG_SMT if SMP 267 select IRQ_FORCED_THREADING 268 select NEED_PER_CPU_EMBED_FIRST_CHUNK 269 select NEED_PER_CPU_PAGE_FIRST_CHUNK 270 select NEED_SG_DMA_LENGTH 271 select PCI_DOMAINS if PCI 272 select PCI_LOCKLESS_CONFIG if PCI 273 select PERF_EVENTS 274 select RTC_LIB 275 select RTC_MC146818_LIB 276 select SPARSE_IRQ 277 select SRCU 278 select SYSCTL_EXCEPTION_TRACE 279 select THREAD_INFO_IN_TASK 280 select TRACE_IRQFLAGS_SUPPORT 281 select TRACE_IRQFLAGS_NMI_SUPPORT 282 select USER_STACKTRACE_SUPPORT 283 select HAVE_ARCH_KCSAN if X86_64 284 select X86_FEATURE_NAMES if PROC_FS 285 select PROC_PID_ARCH_STATUS if PROC_FS 286 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 287 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 288 289config INSTRUCTION_DECODER 290 def_bool y 291 depends on KPROBES || PERF_EVENTS || UPROBES 292 293config OUTPUT_FORMAT 294 string 295 default "elf32-i386" if X86_32 296 default "elf64-x86-64" if X86_64 297 298config LOCKDEP_SUPPORT 299 def_bool y 300 301config STACKTRACE_SUPPORT 302 def_bool y 303 304config MMU 305 def_bool y 306 307config ARCH_MMAP_RND_BITS_MIN 308 default 28 if 64BIT 309 default 8 310 311config ARCH_MMAP_RND_BITS_MAX 312 default 32 if 64BIT 313 default 16 314 315config ARCH_MMAP_RND_COMPAT_BITS_MIN 316 default 8 317 318config ARCH_MMAP_RND_COMPAT_BITS_MAX 319 default 16 320 321config SBUS 322 bool 323 324config GENERIC_ISA_DMA 325 def_bool y 326 depends on ISA_DMA_API 327 328config GENERIC_BUG 329 def_bool y 330 depends on BUG 331 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 332 333config GENERIC_BUG_RELATIVE_POINTERS 334 bool 335 336config ARCH_MAY_HAVE_PC_FDC 337 def_bool y 338 depends on ISA_DMA_API 339 340config GENERIC_CALIBRATE_DELAY 341 def_bool y 342 343config ARCH_HAS_CPU_RELAX 344 def_bool y 345 346config ARCH_HIBERNATION_POSSIBLE 347 def_bool y 348 349config ARCH_NR_GPIO 350 int 351 default 1024 if X86_64 352 default 512 353 354config ARCH_SUSPEND_POSSIBLE 355 def_bool y 356 357config AUDIT_ARCH 358 def_bool y if X86_64 359 360config KASAN_SHADOW_OFFSET 361 hex 362 depends on KASAN 363 default 0xdffffc0000000000 364 365config HAVE_INTEL_TXT 366 def_bool y 367 depends on INTEL_IOMMU && ACPI 368 369config X86_32_SMP 370 def_bool y 371 depends on X86_32 && SMP 372 373config X86_64_SMP 374 def_bool y 375 depends on X86_64 && SMP 376 377config ARCH_SUPPORTS_UPROBES 378 def_bool y 379 380config FIX_EARLYCON_MEM 381 def_bool y 382 383config DYNAMIC_PHYSICAL_MASK 384 bool 385 386config PGTABLE_LEVELS 387 int 388 default 5 if X86_5LEVEL 389 default 4 if X86_64 390 default 3 if X86_PAE 391 default 2 392 393config CC_HAS_SANE_STACKPROTECTOR 394 bool 395 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 396 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 397 help 398 We have to make sure stack protector is unconditionally disabled if 399 the compiler produces broken code or if it does not let us control 400 the segment on 32-bit kernels. 401 402menu "Processor type and features" 403 404config SMP 405 bool "Symmetric multi-processing support" 406 help 407 This enables support for systems with more than one CPU. If you have 408 a system with only one CPU, say N. If you have a system with more 409 than one CPU, say Y. 410 411 If you say N here, the kernel will run on uni- and multiprocessor 412 machines, but will use only one CPU of a multiprocessor machine. If 413 you say Y here, the kernel will run on many, but not all, 414 uniprocessor machines. On a uniprocessor machine, the kernel 415 will run faster if you say N here. 416 417 Note that if you say Y here and choose architecture "586" or 418 "Pentium" under "Processor family", the kernel will not work on 486 419 architectures. Similarly, multiprocessor kernels for the "PPro" 420 architecture may not work on all Pentium based boards. 421 422 People using multiprocessor machines who say Y here should also say 423 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 424 Management" code will be disabled if you say Y here. 425 426 See also <file:Documentation/x86/i386/IO-APIC.rst>, 427 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 428 <http://www.tldp.org/docs.html#howto>. 429 430 If you don't know what to do here, say N. 431 432config X86_FEATURE_NAMES 433 bool "Processor feature human-readable names" if EMBEDDED 434 default y 435 help 436 This option compiles in a table of x86 feature bits and corresponding 437 names. This is required to support /proc/cpuinfo and a few kernel 438 messages. You can disable this to save space, at the expense of 439 making those few kernel messages show numeric feature bits instead. 440 441 If in doubt, say Y. 442 443config X86_X2APIC 444 bool "Support x2apic" 445 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 446 help 447 This enables x2apic support on CPUs that have this feature. 448 449 This allows 32-bit apic IDs (so it can support very large systems), 450 and accesses the local apic via MSRs not via mmio. 451 452 If you don't know what to do here, say N. 453 454config X86_MPPARSE 455 bool "Enable MPS table" if ACPI 456 default y 457 depends on X86_LOCAL_APIC 458 help 459 For old smp systems that do not have proper acpi support. Newer systems 460 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 461 462config GOLDFISH 463 def_bool y 464 depends on X86_GOLDFISH 465 466config X86_CPU_RESCTRL 467 bool "x86 CPU resource control support" 468 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 469 select KERNFS 470 select PROC_CPU_RESCTRL if PROC_FS 471 help 472 Enable x86 CPU resource control support. 473 474 Provide support for the allocation and monitoring of system resources 475 usage by the CPU. 476 477 Intel calls this Intel Resource Director Technology 478 (Intel(R) RDT). More information about RDT can be found in the 479 Intel x86 Architecture Software Developer Manual. 480 481 AMD calls this AMD Platform Quality of Service (AMD QoS). 482 More information about AMD QoS can be found in the AMD64 Technology 483 Platform Quality of Service Extensions manual. 484 485 Say N if unsure. 486 487if X86_32 488config X86_BIGSMP 489 bool "Support for big SMP systems with more than 8 CPUs" 490 depends on SMP 491 help 492 This option is needed for the systems that have more than 8 CPUs. 493 494config X86_EXTENDED_PLATFORM 495 bool "Support for extended (non-PC) x86 platforms" 496 default y 497 help 498 If you disable this option then the kernel will only support 499 standard PC platforms. (which covers the vast majority of 500 systems out there.) 501 502 If you enable this option then you'll be able to select support 503 for the following (non-PC) 32 bit x86 platforms: 504 Goldfish (Android emulator) 505 AMD Elan 506 RDC R-321x SoC 507 SGI 320/540 (Visual Workstation) 508 STA2X11-based (e.g. Northville) 509 Moorestown MID devices 510 511 If you have one of these systems, or if you want to build a 512 generic distribution kernel, say Y here - otherwise say N. 513endif # X86_32 514 515if X86_64 516config X86_EXTENDED_PLATFORM 517 bool "Support for extended (non-PC) x86 platforms" 518 default y 519 help 520 If you disable this option then the kernel will only support 521 standard PC platforms. (which covers the vast majority of 522 systems out there.) 523 524 If you enable this option then you'll be able to select support 525 for the following (non-PC) 64 bit x86 platforms: 526 Numascale NumaChip 527 ScaleMP vSMP 528 SGI Ultraviolet 529 530 If you have one of these systems, or if you want to build a 531 generic distribution kernel, say Y here - otherwise say N. 532endif # X86_64 533# This is an alphabetically sorted list of 64 bit extended platforms 534# Please maintain the alphabetic order if and when there are additions 535config X86_NUMACHIP 536 bool "Numascale NumaChip" 537 depends on X86_64 538 depends on X86_EXTENDED_PLATFORM 539 depends on NUMA 540 depends on SMP 541 depends on X86_X2APIC 542 depends on PCI_MMCONFIG 543 help 544 Adds support for Numascale NumaChip large-SMP systems. Needed to 545 enable more than ~168 cores. 546 If you don't have one of these, you should say N here. 547 548config X86_VSMP 549 bool "ScaleMP vSMP" 550 select HYPERVISOR_GUEST 551 select PARAVIRT 552 depends on X86_64 && PCI 553 depends on X86_EXTENDED_PLATFORM 554 depends on SMP 555 help 556 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 557 supposed to run on these EM64T-based machines. Only choose this option 558 if you have one of these machines. 559 560config X86_UV 561 bool "SGI Ultraviolet" 562 depends on X86_64 563 depends on X86_EXTENDED_PLATFORM 564 depends on NUMA 565 depends on EFI 566 depends on KEXEC_CORE 567 depends on X86_X2APIC 568 depends on PCI 569 help 570 This option is needed in order to support SGI Ultraviolet systems. 571 If you don't have one of these, you should say N here. 572 573# Following is an alphabetically sorted list of 32 bit extended platforms 574# Please maintain the alphabetic order if and when there are additions 575 576config X86_GOLDFISH 577 bool "Goldfish (Virtual Platform)" 578 depends on X86_EXTENDED_PLATFORM 579 help 580 Enable support for the Goldfish virtual platform used primarily 581 for Android development. Unless you are building for the Android 582 Goldfish emulator say N here. 583 584config X86_INTEL_CE 585 bool "CE4100 TV platform" 586 depends on PCI 587 depends on PCI_GODIRECT 588 depends on X86_IO_APIC 589 depends on X86_32 590 depends on X86_EXTENDED_PLATFORM 591 select X86_REBOOTFIXUPS 592 select OF 593 select OF_EARLY_FLATTREE 594 help 595 Select for the Intel CE media processor (CE4100) SOC. 596 This option compiles in support for the CE4100 SOC for settop 597 boxes and media devices. 598 599config X86_INTEL_MID 600 bool "Intel MID platform support" 601 depends on X86_EXTENDED_PLATFORM 602 depends on X86_PLATFORM_DEVICES 603 depends on PCI 604 depends on X86_64 || (PCI_GOANY && X86_32) 605 depends on X86_IO_APIC 606 select I2C 607 select DW_APB_TIMER 608 select INTEL_SCU_PCI 609 help 610 Select to build a kernel capable of supporting Intel MID (Mobile 611 Internet Device) platform systems which do not have the PCI legacy 612 interfaces. If you are building for a PC class system say N here. 613 614 Intel MID platforms are based on an Intel processor and chipset which 615 consume less power than most of the x86 derivatives. 616 617config X86_INTEL_QUARK 618 bool "Intel Quark platform support" 619 depends on X86_32 620 depends on X86_EXTENDED_PLATFORM 621 depends on X86_PLATFORM_DEVICES 622 depends on X86_TSC 623 depends on PCI 624 depends on PCI_GOANY 625 depends on X86_IO_APIC 626 select IOSF_MBI 627 select INTEL_IMR 628 select COMMON_CLK 629 help 630 Select to include support for Quark X1000 SoC. 631 Say Y here if you have a Quark based system such as the Arduino 632 compatible Intel Galileo. 633 634config X86_INTEL_LPSS 635 bool "Intel Low Power Subsystem Support" 636 depends on X86 && ACPI && PCI 637 select COMMON_CLK 638 select PINCTRL 639 select IOSF_MBI 640 help 641 Select to build support for Intel Low Power Subsystem such as 642 found on Intel Lynxpoint PCH. Selecting this option enables 643 things like clock tree (common clock framework) and pincontrol 644 which are needed by the LPSS peripheral drivers. 645 646config X86_AMD_PLATFORM_DEVICE 647 bool "AMD ACPI2Platform devices support" 648 depends on ACPI 649 select COMMON_CLK 650 select PINCTRL 651 help 652 Select to interpret AMD specific ACPI device to platform device 653 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 654 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 655 implemented under PINCTRL subsystem. 656 657config IOSF_MBI 658 tristate "Intel SoC IOSF Sideband support for SoC platforms" 659 depends on PCI 660 help 661 This option enables sideband register access support for Intel SoC 662 platforms. On these platforms the IOSF sideband is used in lieu of 663 MSR's for some register accesses, mostly but not limited to thermal 664 and power. Drivers may query the availability of this device to 665 determine if they need the sideband in order to work on these 666 platforms. The sideband is available on the following SoC products. 667 This list is not meant to be exclusive. 668 - BayTrail 669 - Braswell 670 - Quark 671 672 You should say Y if you are running a kernel on one of these SoC's. 673 674config IOSF_MBI_DEBUG 675 bool "Enable IOSF sideband access through debugfs" 676 depends on IOSF_MBI && DEBUG_FS 677 help 678 Select this option to expose the IOSF sideband access registers (MCR, 679 MDR, MCRX) through debugfs to write and read register information from 680 different units on the SoC. This is most useful for obtaining device 681 state information for debug and analysis. As this is a general access 682 mechanism, users of this option would have specific knowledge of the 683 device they want to access. 684 685 If you don't require the option or are in doubt, say N. 686 687config X86_RDC321X 688 bool "RDC R-321x SoC" 689 depends on X86_32 690 depends on X86_EXTENDED_PLATFORM 691 select M486 692 select X86_REBOOTFIXUPS 693 help 694 This option is needed for RDC R-321x system-on-chip, also known 695 as R-8610-(G). 696 If you don't have one of these chips, you should say N here. 697 698config X86_32_NON_STANDARD 699 bool "Support non-standard 32-bit SMP architectures" 700 depends on X86_32 && SMP 701 depends on X86_EXTENDED_PLATFORM 702 help 703 This option compiles in the bigsmp and STA2X11 default 704 subarchitectures. It is intended for a generic binary 705 kernel. If you select them all, kernel will probe it one by 706 one and will fallback to default. 707 708# Alphabetically sorted list of Non standard 32 bit platforms 709 710config X86_SUPPORTS_MEMORY_FAILURE 711 def_bool y 712 # MCE code calls memory_failure(): 713 depends on X86_MCE 714 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 715 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 716 depends on X86_64 || !SPARSEMEM 717 select ARCH_SUPPORTS_MEMORY_FAILURE 718 719config STA2X11 720 bool "STA2X11 Companion Chip Support" 721 depends on X86_32_NON_STANDARD && PCI 722 select SWIOTLB 723 select MFD_STA2X11 724 select GPIOLIB 725 help 726 This adds support for boards based on the STA2X11 IO-Hub, 727 a.k.a. "ConneXt". The chip is used in place of the standard 728 PC chipset, so all "standard" peripherals are missing. If this 729 option is selected the kernel will still be able to boot on 730 standard PC machines. 731 732config X86_32_IRIS 733 tristate "Eurobraille/Iris poweroff module" 734 depends on X86_32 735 help 736 The Iris machines from EuroBraille do not have APM or ACPI support 737 to shut themselves down properly. A special I/O sequence is 738 needed to do so, which is what this module does at 739 kernel shutdown. 740 741 This is only for Iris machines from EuroBraille. 742 743 If unused, say N. 744 745config SCHED_OMIT_FRAME_POINTER 746 def_bool y 747 prompt "Single-depth WCHAN output" 748 depends on X86 749 help 750 Calculate simpler /proc/<PID>/wchan values. If this option 751 is disabled then wchan values will recurse back to the 752 caller function. This provides more accurate wchan values, 753 at the expense of slightly more scheduling overhead. 754 755 If in doubt, say "Y". 756 757menuconfig HYPERVISOR_GUEST 758 bool "Linux guest support" 759 help 760 Say Y here to enable options for running Linux under various hyper- 761 visors. This option enables basic hypervisor detection and platform 762 setup. 763 764 If you say N, all options in this submenu will be skipped and 765 disabled, and Linux guest support won't be built in. 766 767if HYPERVISOR_GUEST 768 769config PARAVIRT 770 bool "Enable paravirtualization code" 771 depends on HAVE_STATIC_CALL 772 help 773 This changes the kernel so it can modify itself when it is run 774 under a hypervisor, potentially improving performance significantly 775 over full virtualization. However, when run without a hypervisor 776 the kernel is theoretically slower and slightly larger. 777 778config PARAVIRT_XXL 779 bool 780 781config PARAVIRT_DEBUG 782 bool "paravirt-ops debugging" 783 depends on PARAVIRT && DEBUG_KERNEL 784 help 785 Enable to debug paravirt_ops internals. Specifically, BUG if 786 a paravirt_op is missing when it is called. 787 788config PARAVIRT_SPINLOCKS 789 bool "Paravirtualization layer for spinlocks" 790 depends on PARAVIRT && SMP 791 help 792 Paravirtualized spinlocks allow a pvops backend to replace the 793 spinlock implementation with something virtualization-friendly 794 (for example, block the virtual CPU rather than spinning). 795 796 It has a minimal impact on native kernels and gives a nice performance 797 benefit on paravirtualized KVM / Xen kernels. 798 799 If you are unsure how to answer this question, answer Y. 800 801config X86_HV_CALLBACK_VECTOR 802 def_bool n 803 804source "arch/x86/xen/Kconfig" 805 806config KVM_GUEST 807 bool "KVM Guest support (including kvmclock)" 808 depends on PARAVIRT 809 select PARAVIRT_CLOCK 810 select ARCH_CPUIDLE_HALTPOLL 811 select X86_HV_CALLBACK_VECTOR 812 default y 813 help 814 This option enables various optimizations for running under the KVM 815 hypervisor. It includes a paravirtualized clock, so that instead 816 of relying on a PIT (or probably other) emulation by the 817 underlying device model, the host provides the guest with 818 timing infrastructure such as time of day, and system time 819 820config ARCH_CPUIDLE_HALTPOLL 821 def_bool n 822 prompt "Disable host haltpoll when loading haltpoll driver" 823 help 824 If virtualized under KVM, disable host haltpoll. 825 826config PVH 827 bool "Support for running PVH guests" 828 help 829 This option enables the PVH entry point for guest virtual machines 830 as specified in the x86/HVM direct boot ABI. 831 832config PARAVIRT_TIME_ACCOUNTING 833 bool "Paravirtual steal time accounting" 834 depends on PARAVIRT 835 help 836 Select this option to enable fine granularity task steal time 837 accounting. Time spent executing other tasks in parallel with 838 the current vCPU is discounted from the vCPU power. To account for 839 that, there can be a small performance impact. 840 841 If in doubt, say N here. 842 843config PARAVIRT_CLOCK 844 bool 845 846config JAILHOUSE_GUEST 847 bool "Jailhouse non-root cell support" 848 depends on X86_64 && PCI 849 select X86_PM_TIMER 850 help 851 This option allows to run Linux as guest in a Jailhouse non-root 852 cell. You can leave this option disabled if you only want to start 853 Jailhouse and run Linux afterwards in the root cell. 854 855config ACRN_GUEST 856 bool "ACRN Guest support" 857 depends on X86_64 858 select X86_HV_CALLBACK_VECTOR 859 help 860 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 861 a flexible, lightweight reference open-source hypervisor, built with 862 real-time and safety-criticality in mind. It is built for embedded 863 IOT with small footprint and real-time features. More details can be 864 found in https://projectacrn.org/. 865 866config INTEL_TDX_GUEST 867 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 868 depends on X86_64 && CPU_SUP_INTEL 869 depends on X86_X2APIC 870 select ARCH_HAS_CC_PLATFORM 871 select X86_MEM_ENCRYPT 872 select X86_MCE 873 help 874 Support running as a guest under Intel TDX. Without this support, 875 the guest kernel can not boot or run under TDX. 876 TDX includes memory encryption and integrity capabilities 877 which protect the confidentiality and integrity of guest 878 memory contents and CPU state. TDX guests are protected from 879 some attacks from the VMM. 880 881endif # HYPERVISOR_GUEST 882 883source "arch/x86/Kconfig.cpu" 884 885config HPET_TIMER 886 def_bool X86_64 887 prompt "HPET Timer Support" if X86_32 888 help 889 Use the IA-PC HPET (High Precision Event Timer) to manage 890 time in preference to the PIT and RTC, if a HPET is 891 present. 892 HPET is the next generation timer replacing legacy 8254s. 893 The HPET provides a stable time base on SMP 894 systems, unlike the TSC, but it is more expensive to access, 895 as it is off-chip. The interface used is documented 896 in the HPET spec, revision 1. 897 898 You can safely choose Y here. However, HPET will only be 899 activated if the platform and the BIOS support this feature. 900 Otherwise the 8254 will be used for timing services. 901 902 Choose N to continue using the legacy 8254 timer. 903 904config HPET_EMULATE_RTC 905 def_bool y 906 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 907 908# Mark as expert because too many people got it wrong. 909# The code disables itself when not needed. 910config DMI 911 default y 912 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 913 bool "Enable DMI scanning" if EXPERT 914 help 915 Enabled scanning of DMI to identify machine quirks. Say Y 916 here unless you have verified that your setup is not 917 affected by entries in the DMI blacklist. Required by PNP 918 BIOS code. 919 920config GART_IOMMU 921 bool "Old AMD GART IOMMU support" 922 select DMA_OPS 923 select IOMMU_HELPER 924 select SWIOTLB 925 depends on X86_64 && PCI && AMD_NB 926 help 927 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 928 GART based hardware IOMMUs. 929 930 The GART supports full DMA access for devices with 32-bit access 931 limitations, on systems with more than 3 GB. This is usually needed 932 for USB, sound, many IDE/SATA chipsets and some other devices. 933 934 Newer systems typically have a modern AMD IOMMU, supported via 935 the CONFIG_AMD_IOMMU=y config option. 936 937 In normal configurations this driver is only active when needed: 938 there's more than 3 GB of memory and the system contains a 939 32-bit limited device. 940 941 If unsure, say Y. 942 943config BOOT_VESA_SUPPORT 944 bool 945 help 946 If true, at least one selected framebuffer driver can take advantage 947 of VESA video modes set at an early boot stage via the vga= parameter. 948 949config MAXSMP 950 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 951 depends on X86_64 && SMP && DEBUG_KERNEL 952 select CPUMASK_OFFSTACK 953 help 954 Enable maximum number of CPUS and NUMA Nodes for this architecture. 955 If unsure, say N. 956 957# 958# The maximum number of CPUs supported: 959# 960# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 961# and which can be configured interactively in the 962# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 963# 964# The ranges are different on 32-bit and 64-bit kernels, depending on 965# hardware capabilities and scalability features of the kernel. 966# 967# ( If MAXSMP is enabled we just use the highest possible value and disable 968# interactive configuration. ) 969# 970 971config NR_CPUS_RANGE_BEGIN 972 int 973 default NR_CPUS_RANGE_END if MAXSMP 974 default 1 if !SMP 975 default 2 976 977config NR_CPUS_RANGE_END 978 int 979 depends on X86_32 980 default 64 if SMP && X86_BIGSMP 981 default 8 if SMP && !X86_BIGSMP 982 default 1 if !SMP 983 984config NR_CPUS_RANGE_END 985 int 986 depends on X86_64 987 default 8192 if SMP && CPUMASK_OFFSTACK 988 default 512 if SMP && !CPUMASK_OFFSTACK 989 default 1 if !SMP 990 991config NR_CPUS_DEFAULT 992 int 993 depends on X86_32 994 default 32 if X86_BIGSMP 995 default 8 if SMP 996 default 1 if !SMP 997 998config NR_CPUS_DEFAULT 999 int 1000 depends on X86_64 1001 default 8192 if MAXSMP 1002 default 64 if SMP 1003 default 1 if !SMP 1004 1005config NR_CPUS 1006 int "Maximum number of CPUs" if SMP && !MAXSMP 1007 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1008 default NR_CPUS_DEFAULT 1009 help 1010 This allows you to specify the maximum number of CPUs which this 1011 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1012 supported value is 8192, otherwise the maximum value is 512. The 1013 minimum value which makes sense is 2. 1014 1015 This is purely to save memory: each supported CPU adds about 8KB 1016 to the kernel image. 1017 1018config SCHED_CLUSTER 1019 bool "Cluster scheduler support" 1020 depends on SMP 1021 default y 1022 help 1023 Cluster scheduler support improves the CPU scheduler's decision 1024 making when dealing with machines that have clusters of CPUs. 1025 Cluster usually means a couple of CPUs which are placed closely 1026 by sharing mid-level caches, last-level cache tags or internal 1027 busses. 1028 1029config SCHED_SMT 1030 def_bool y if SMP 1031 1032config SCHED_MC 1033 def_bool y 1034 prompt "Multi-core scheduler support" 1035 depends on SMP 1036 help 1037 Multi-core scheduler support improves the CPU scheduler's decision 1038 making when dealing with multi-core CPU chips at a cost of slightly 1039 increased overhead in some places. If unsure say N here. 1040 1041config SCHED_MC_PRIO 1042 bool "CPU core priorities scheduler support" 1043 depends on SCHED_MC && CPU_SUP_INTEL 1044 select X86_INTEL_PSTATE 1045 select CPU_FREQ 1046 default y 1047 help 1048 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1049 core ordering determined at manufacturing time, which allows 1050 certain cores to reach higher turbo frequencies (when running 1051 single threaded workloads) than others. 1052 1053 Enabling this kernel feature teaches the scheduler about 1054 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1055 scheduler's CPU selection logic accordingly, so that higher 1056 overall system performance can be achieved. 1057 1058 This feature will have no effect on CPUs without this feature. 1059 1060 If unsure say Y here. 1061 1062config UP_LATE_INIT 1063 def_bool y 1064 depends on !SMP && X86_LOCAL_APIC 1065 1066config X86_UP_APIC 1067 bool "Local APIC support on uniprocessors" if !PCI_MSI 1068 default PCI_MSI 1069 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1070 help 1071 A local APIC (Advanced Programmable Interrupt Controller) is an 1072 integrated interrupt controller in the CPU. If you have a single-CPU 1073 system which has a processor with a local APIC, you can say Y here to 1074 enable and use it. If you say Y here even though your machine doesn't 1075 have a local APIC, then the kernel will still run with no slowdown at 1076 all. The local APIC supports CPU-generated self-interrupts (timer, 1077 performance counters), and the NMI watchdog which detects hard 1078 lockups. 1079 1080config X86_UP_IOAPIC 1081 bool "IO-APIC support on uniprocessors" 1082 depends on X86_UP_APIC 1083 help 1084 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1085 SMP-capable replacement for PC-style interrupt controllers. Most 1086 SMP systems and many recent uniprocessor systems have one. 1087 1088 If you have a single-CPU system with an IO-APIC, you can say Y here 1089 to use it. If you say Y here even though your machine doesn't have 1090 an IO-APIC, then the kernel will still run with no slowdown at all. 1091 1092config X86_LOCAL_APIC 1093 def_bool y 1094 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1095 select IRQ_DOMAIN_HIERARCHY 1096 select PCI_MSI_IRQ_DOMAIN if PCI_MSI 1097 1098config X86_IO_APIC 1099 def_bool y 1100 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1101 1102config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1103 bool "Reroute for broken boot IRQs" 1104 depends on X86_IO_APIC 1105 help 1106 This option enables a workaround that fixes a source of 1107 spurious interrupts. This is recommended when threaded 1108 interrupt handling is used on systems where the generation of 1109 superfluous "boot interrupts" cannot be disabled. 1110 1111 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1112 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1113 kernel does during interrupt handling). On chipsets where this 1114 boot IRQ generation cannot be disabled, this workaround keeps 1115 the original IRQ line masked so that only the equivalent "boot 1116 IRQ" is delivered to the CPUs. The workaround also tells the 1117 kernel to set up the IRQ handler on the boot IRQ line. In this 1118 way only one interrupt is delivered to the kernel. Otherwise 1119 the spurious second interrupt may cause the kernel to bring 1120 down (vital) interrupt lines. 1121 1122 Only affects "broken" chipsets. Interrupt sharing may be 1123 increased on these systems. 1124 1125config X86_MCE 1126 bool "Machine Check / overheating reporting" 1127 select GENERIC_ALLOCATOR 1128 default y 1129 help 1130 Machine Check support allows the processor to notify the 1131 kernel if it detects a problem (e.g. overheating, data corruption). 1132 The action the kernel takes depends on the severity of the problem, 1133 ranging from warning messages to halting the machine. 1134 1135config X86_MCELOG_LEGACY 1136 bool "Support for deprecated /dev/mcelog character device" 1137 depends on X86_MCE 1138 help 1139 Enable support for /dev/mcelog which is needed by the old mcelog 1140 userspace logging daemon. Consider switching to the new generation 1141 rasdaemon solution. 1142 1143config X86_MCE_INTEL 1144 def_bool y 1145 prompt "Intel MCE features" 1146 depends on X86_MCE && X86_LOCAL_APIC 1147 help 1148 Additional support for intel specific MCE features such as 1149 the thermal monitor. 1150 1151config X86_MCE_AMD 1152 def_bool y 1153 prompt "AMD MCE features" 1154 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1155 help 1156 Additional support for AMD specific MCE features such as 1157 the DRAM Error Threshold. 1158 1159config X86_ANCIENT_MCE 1160 bool "Support for old Pentium 5 / WinChip machine checks" 1161 depends on X86_32 && X86_MCE 1162 help 1163 Include support for machine check handling on old Pentium 5 or WinChip 1164 systems. These typically need to be enabled explicitly on the command 1165 line. 1166 1167config X86_MCE_THRESHOLD 1168 depends on X86_MCE_AMD || X86_MCE_INTEL 1169 def_bool y 1170 1171config X86_MCE_INJECT 1172 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1173 tristate "Machine check injector support" 1174 help 1175 Provide support for injecting machine checks for testing purposes. 1176 If you don't know what a machine check is and you don't do kernel 1177 QA it is safe to say n. 1178 1179source "arch/x86/events/Kconfig" 1180 1181config X86_LEGACY_VM86 1182 bool "Legacy VM86 support" 1183 depends on X86_32 1184 help 1185 This option allows user programs to put the CPU into V8086 1186 mode, which is an 80286-era approximation of 16-bit real mode. 1187 1188 Some very old versions of X and/or vbetool require this option 1189 for user mode setting. Similarly, DOSEMU will use it if 1190 available to accelerate real mode DOS programs. However, any 1191 recent version of DOSEMU, X, or vbetool should be fully 1192 functional even without kernel VM86 support, as they will all 1193 fall back to software emulation. Nevertheless, if you are using 1194 a 16-bit DOS program where 16-bit performance matters, vm86 1195 mode might be faster than emulation and you might want to 1196 enable this option. 1197 1198 Note that any app that works on a 64-bit kernel is unlikely to 1199 need this option, as 64-bit kernels don't, and can't, support 1200 V8086 mode. This option is also unrelated to 16-bit protected 1201 mode and is not needed to run most 16-bit programs under Wine. 1202 1203 Enabling this option increases the complexity of the kernel 1204 and slows down exception handling a tiny bit. 1205 1206 If unsure, say N here. 1207 1208config VM86 1209 bool 1210 default X86_LEGACY_VM86 1211 1212config X86_16BIT 1213 bool "Enable support for 16-bit segments" if EXPERT 1214 default y 1215 depends on MODIFY_LDT_SYSCALL 1216 help 1217 This option is required by programs like Wine to run 16-bit 1218 protected mode legacy code on x86 processors. Disabling 1219 this option saves about 300 bytes on i386, or around 6K text 1220 plus 16K runtime memory on x86-64, 1221 1222config X86_ESPFIX32 1223 def_bool y 1224 depends on X86_16BIT && X86_32 1225 1226config X86_ESPFIX64 1227 def_bool y 1228 depends on X86_16BIT && X86_64 1229 1230config X86_VSYSCALL_EMULATION 1231 bool "Enable vsyscall emulation" if EXPERT 1232 default y 1233 depends on X86_64 1234 help 1235 This enables emulation of the legacy vsyscall page. Disabling 1236 it is roughly equivalent to booting with vsyscall=none, except 1237 that it will also disable the helpful warning if a program 1238 tries to use a vsyscall. With this option set to N, offending 1239 programs will just segfault, citing addresses of the form 1240 0xffffffffff600?00. 1241 1242 This option is required by many programs built before 2013, and 1243 care should be used even with newer programs if set to N. 1244 1245 Disabling this option saves about 7K of kernel size and 1246 possibly 4K of additional runtime pagetable memory. 1247 1248config X86_IOPL_IOPERM 1249 bool "IOPERM and IOPL Emulation" 1250 default y 1251 help 1252 This enables the ioperm() and iopl() syscalls which are necessary 1253 for legacy applications. 1254 1255 Legacy IOPL support is an overbroad mechanism which allows user 1256 space aside of accessing all 65536 I/O ports also to disable 1257 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1258 capabilities and permission from potentially active security 1259 modules. 1260 1261 The emulation restricts the functionality of the syscall to 1262 only allowing the full range I/O port access, but prevents the 1263 ability to disable interrupts from user space which would be 1264 granted if the hardware IOPL mechanism would be used. 1265 1266config TOSHIBA 1267 tristate "Toshiba Laptop support" 1268 depends on X86_32 1269 help 1270 This adds a driver to safely access the System Management Mode of 1271 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1272 not work on models with a Phoenix BIOS. The System Management Mode 1273 is used to set the BIOS and power saving options on Toshiba portables. 1274 1275 For information on utilities to make use of this driver see the 1276 Toshiba Linux utilities web site at: 1277 <http://www.buzzard.org.uk/toshiba/>. 1278 1279 Say Y if you intend to run this kernel on a Toshiba portable. 1280 Say N otherwise. 1281 1282config X86_REBOOTFIXUPS 1283 bool "Enable X86 board specific fixups for reboot" 1284 depends on X86_32 1285 help 1286 This enables chipset and/or board specific fixups to be done 1287 in order to get reboot to work correctly. This is only needed on 1288 some combinations of hardware and BIOS. The symptom, for which 1289 this config is intended, is when reboot ends with a stalled/hung 1290 system. 1291 1292 Currently, the only fixup is for the Geode machines using 1293 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1294 1295 Say Y if you want to enable the fixup. Currently, it's safe to 1296 enable this option even if you don't need it. 1297 Say N otherwise. 1298 1299config MICROCODE 1300 bool "CPU microcode loading support" 1301 default y 1302 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1303 help 1304 If you say Y here, you will be able to update the microcode on 1305 Intel and AMD processors. The Intel support is for the IA32 family, 1306 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1307 AMD support is for families 0x10 and later. You will obviously need 1308 the actual microcode binary data itself which is not shipped with 1309 the Linux kernel. 1310 1311 The preferred method to load microcode from a detached initrd is described 1312 in Documentation/x86/microcode.rst. For that you need to enable 1313 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1314 initrd for microcode blobs. 1315 1316 In addition, you can build the microcode into the kernel. For that you 1317 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1318 config option. 1319 1320config MICROCODE_INTEL 1321 bool "Intel microcode loading support" 1322 depends on CPU_SUP_INTEL && MICROCODE 1323 default MICROCODE 1324 help 1325 This options enables microcode patch loading support for Intel 1326 processors. 1327 1328 For the current Intel microcode data package go to 1329 <https://downloadcenter.intel.com> and search for 1330 'Linux Processor Microcode Data File'. 1331 1332config MICROCODE_AMD 1333 bool "AMD microcode loading support" 1334 depends on CPU_SUP_AMD && MICROCODE 1335 help 1336 If you select this option, microcode patch loading support for AMD 1337 processors will be enabled. 1338 1339config MICROCODE_LATE_LOADING 1340 bool "Late microcode loading (DANGEROUS)" 1341 default n 1342 depends on MICROCODE 1343 help 1344 Loading microcode late, when the system is up and executing instructions 1345 is a tricky business and should be avoided if possible. Just the sequence 1346 of synchronizing all cores and SMT threads is one fragile dance which does 1347 not guarantee that cores might not softlock after the loading. Therefore, 1348 use this at your own risk. Late loading taints the kernel too. 1349 1350config X86_MSR 1351 tristate "/dev/cpu/*/msr - Model-specific register support" 1352 help 1353 This device gives privileged processes access to the x86 1354 Model-Specific Registers (MSRs). It is a character device with 1355 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1356 MSR accesses are directed to a specific CPU on multi-processor 1357 systems. 1358 1359config X86_CPUID 1360 tristate "/dev/cpu/*/cpuid - CPU information support" 1361 help 1362 This device gives processes access to the x86 CPUID instruction to 1363 be executed on a specific processor. It is a character device 1364 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1365 /dev/cpu/31/cpuid. 1366 1367choice 1368 prompt "High Memory Support" 1369 default HIGHMEM4G 1370 depends on X86_32 1371 1372config NOHIGHMEM 1373 bool "off" 1374 help 1375 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1376 However, the address space of 32-bit x86 processors is only 4 1377 Gigabytes large. That means that, if you have a large amount of 1378 physical memory, not all of it can be "permanently mapped" by the 1379 kernel. The physical memory that's not permanently mapped is called 1380 "high memory". 1381 1382 If you are compiling a kernel which will never run on a machine with 1383 more than 1 Gigabyte total physical RAM, answer "off" here (default 1384 choice and suitable for most users). This will result in a "3GB/1GB" 1385 split: 3GB are mapped so that each process sees a 3GB virtual memory 1386 space and the remaining part of the 4GB virtual memory space is used 1387 by the kernel to permanently map as much physical memory as 1388 possible. 1389 1390 If the machine has between 1 and 4 Gigabytes physical RAM, then 1391 answer "4GB" here. 1392 1393 If more than 4 Gigabytes is used then answer "64GB" here. This 1394 selection turns Intel PAE (Physical Address Extension) mode on. 1395 PAE implements 3-level paging on IA32 processors. PAE is fully 1396 supported by Linux, PAE mode is implemented on all recent Intel 1397 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1398 then the kernel will not boot on CPUs that don't support PAE! 1399 1400 The actual amount of total physical memory will either be 1401 auto detected or can be forced by using a kernel command line option 1402 such as "mem=256M". (Try "man bootparam" or see the documentation of 1403 your boot loader (lilo or loadlin) about how to pass options to the 1404 kernel at boot time.) 1405 1406 If unsure, say "off". 1407 1408config HIGHMEM4G 1409 bool "4GB" 1410 help 1411 Select this if you have a 32-bit processor and between 1 and 4 1412 gigabytes of physical RAM. 1413 1414config HIGHMEM64G 1415 bool "64GB" 1416 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1417 select X86_PAE 1418 help 1419 Select this if you have a 32-bit processor and more than 4 1420 gigabytes of physical RAM. 1421 1422endchoice 1423 1424choice 1425 prompt "Memory split" if EXPERT 1426 default VMSPLIT_3G 1427 depends on X86_32 1428 help 1429 Select the desired split between kernel and user memory. 1430 1431 If the address range available to the kernel is less than the 1432 physical memory installed, the remaining memory will be available 1433 as "high memory". Accessing high memory is a little more costly 1434 than low memory, as it needs to be mapped into the kernel first. 1435 Note that increasing the kernel address space limits the range 1436 available to user programs, making the address space there 1437 tighter. Selecting anything other than the default 3G/1G split 1438 will also likely make your kernel incompatible with binary-only 1439 kernel modules. 1440 1441 If you are not absolutely sure what you are doing, leave this 1442 option alone! 1443 1444 config VMSPLIT_3G 1445 bool "3G/1G user/kernel split" 1446 config VMSPLIT_3G_OPT 1447 depends on !X86_PAE 1448 bool "3G/1G user/kernel split (for full 1G low memory)" 1449 config VMSPLIT_2G 1450 bool "2G/2G user/kernel split" 1451 config VMSPLIT_2G_OPT 1452 depends on !X86_PAE 1453 bool "2G/2G user/kernel split (for full 2G low memory)" 1454 config VMSPLIT_1G 1455 bool "1G/3G user/kernel split" 1456endchoice 1457 1458config PAGE_OFFSET 1459 hex 1460 default 0xB0000000 if VMSPLIT_3G_OPT 1461 default 0x80000000 if VMSPLIT_2G 1462 default 0x78000000 if VMSPLIT_2G_OPT 1463 default 0x40000000 if VMSPLIT_1G 1464 default 0xC0000000 1465 depends on X86_32 1466 1467config HIGHMEM 1468 def_bool y 1469 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1470 1471config X86_PAE 1472 bool "PAE (Physical Address Extension) Support" 1473 depends on X86_32 && !HIGHMEM4G 1474 select PHYS_ADDR_T_64BIT 1475 select SWIOTLB 1476 help 1477 PAE is required for NX support, and furthermore enables 1478 larger swapspace support for non-overcommit purposes. It 1479 has the cost of more pagetable lookup overhead, and also 1480 consumes more pagetable space per process. 1481 1482config X86_5LEVEL 1483 bool "Enable 5-level page tables support" 1484 default y 1485 select DYNAMIC_MEMORY_LAYOUT 1486 select SPARSEMEM_VMEMMAP 1487 depends on X86_64 1488 help 1489 5-level paging enables access to larger address space: 1490 upto 128 PiB of virtual address space and 4 PiB of 1491 physical address space. 1492 1493 It will be supported by future Intel CPUs. 1494 1495 A kernel with the option enabled can be booted on machines that 1496 support 4- or 5-level paging. 1497 1498 See Documentation/x86/x86_64/5level-paging.rst for more 1499 information. 1500 1501 Say N if unsure. 1502 1503config X86_DIRECT_GBPAGES 1504 def_bool y 1505 depends on X86_64 1506 help 1507 Certain kernel features effectively disable kernel 1508 linear 1 GB mappings (even if the CPU otherwise 1509 supports them), so don't confuse the user by printing 1510 that we have them enabled. 1511 1512config X86_CPA_STATISTICS 1513 bool "Enable statistic for Change Page Attribute" 1514 depends on DEBUG_FS 1515 help 1516 Expose statistics about the Change Page Attribute mechanism, which 1517 helps to determine the effectiveness of preserving large and huge 1518 page mappings when mapping protections are changed. 1519 1520config X86_MEM_ENCRYPT 1521 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1522 select DYNAMIC_PHYSICAL_MASK 1523 def_bool n 1524 1525config AMD_MEM_ENCRYPT 1526 bool "AMD Secure Memory Encryption (SME) support" 1527 depends on X86_64 && CPU_SUP_AMD 1528 select DMA_COHERENT_POOL 1529 select ARCH_USE_MEMREMAP_PROT 1530 select INSTRUCTION_DECODER 1531 select ARCH_HAS_CC_PLATFORM 1532 select X86_MEM_ENCRYPT 1533 help 1534 Say yes to enable support for the encryption of system memory. 1535 This requires an AMD processor that supports Secure Memory 1536 Encryption (SME). 1537 1538config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1539 bool "Activate AMD Secure Memory Encryption (SME) by default" 1540 depends on AMD_MEM_ENCRYPT 1541 help 1542 Say yes to have system memory encrypted by default if running on 1543 an AMD processor that supports Secure Memory Encryption (SME). 1544 1545 If set to Y, then the encryption of system memory can be 1546 deactivated with the mem_encrypt=off command line option. 1547 1548 If set to N, then the encryption of system memory can be 1549 activated with the mem_encrypt=on command line option. 1550 1551# Common NUMA Features 1552config NUMA 1553 bool "NUMA Memory Allocation and Scheduler Support" 1554 depends on SMP 1555 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1556 default y if X86_BIGSMP 1557 select USE_PERCPU_NUMA_NODE_ID 1558 help 1559 Enable NUMA (Non-Uniform Memory Access) support. 1560 1561 The kernel will try to allocate memory used by a CPU on the 1562 local memory controller of the CPU and add some more 1563 NUMA awareness to the kernel. 1564 1565 For 64-bit this is recommended if the system is Intel Core i7 1566 (or later), AMD Opteron, or EM64T NUMA. 1567 1568 For 32-bit this is only needed if you boot a 32-bit 1569 kernel on a 64-bit NUMA platform. 1570 1571 Otherwise, you should say N. 1572 1573config AMD_NUMA 1574 def_bool y 1575 prompt "Old style AMD Opteron NUMA detection" 1576 depends on X86_64 && NUMA && PCI 1577 help 1578 Enable AMD NUMA node topology detection. You should say Y here if 1579 you have a multi processor AMD system. This uses an old method to 1580 read the NUMA configuration directly from the builtin Northbridge 1581 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1582 which also takes priority if both are compiled in. 1583 1584config X86_64_ACPI_NUMA 1585 def_bool y 1586 prompt "ACPI NUMA detection" 1587 depends on X86_64 && NUMA && ACPI && PCI 1588 select ACPI_NUMA 1589 help 1590 Enable ACPI SRAT based node topology detection. 1591 1592config NUMA_EMU 1593 bool "NUMA emulation" 1594 depends on NUMA 1595 help 1596 Enable NUMA emulation. A flat machine will be split 1597 into virtual nodes when booted with "numa=fake=N", where N is the 1598 number of nodes. This is only useful for debugging. 1599 1600config NODES_SHIFT 1601 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1602 range 1 10 1603 default "10" if MAXSMP 1604 default "6" if X86_64 1605 default "3" 1606 depends on NUMA 1607 help 1608 Specify the maximum number of NUMA Nodes available on the target 1609 system. Increases memory reserved to accommodate various tables. 1610 1611config ARCH_FLATMEM_ENABLE 1612 def_bool y 1613 depends on X86_32 && !NUMA 1614 1615config ARCH_SPARSEMEM_ENABLE 1616 def_bool y 1617 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1618 select SPARSEMEM_STATIC if X86_32 1619 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1620 1621config ARCH_SPARSEMEM_DEFAULT 1622 def_bool X86_64 || (NUMA && X86_32) 1623 1624config ARCH_SELECT_MEMORY_MODEL 1625 def_bool y 1626 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1627 1628config ARCH_MEMORY_PROBE 1629 bool "Enable sysfs memory/probe interface" 1630 depends on MEMORY_HOTPLUG 1631 help 1632 This option enables a sysfs memory/probe interface for testing. 1633 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1634 If you are unsure how to answer this question, answer N. 1635 1636config ARCH_PROC_KCORE_TEXT 1637 def_bool y 1638 depends on X86_64 && PROC_KCORE 1639 1640config ILLEGAL_POINTER_VALUE 1641 hex 1642 default 0 if X86_32 1643 default 0xdead000000000000 if X86_64 1644 1645config X86_PMEM_LEGACY_DEVICE 1646 bool 1647 1648config X86_PMEM_LEGACY 1649 tristate "Support non-standard NVDIMMs and ADR protected memory" 1650 depends on PHYS_ADDR_T_64BIT 1651 depends on BLK_DEV 1652 select X86_PMEM_LEGACY_DEVICE 1653 select NUMA_KEEP_MEMINFO if NUMA 1654 select LIBNVDIMM 1655 help 1656 Treat memory marked using the non-standard e820 type of 12 as used 1657 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1658 The kernel will offer these regions to the 'pmem' driver so 1659 they can be used for persistent storage. 1660 1661 Say Y if unsure. 1662 1663config HIGHPTE 1664 bool "Allocate 3rd-level pagetables from highmem" 1665 depends on HIGHMEM 1666 help 1667 The VM uses one page table entry for each page of physical memory. 1668 For systems with a lot of RAM, this can be wasteful of precious 1669 low memory. Setting this option will put user-space page table 1670 entries in high memory. 1671 1672config X86_CHECK_BIOS_CORRUPTION 1673 bool "Check for low memory corruption" 1674 help 1675 Periodically check for memory corruption in low memory, which 1676 is suspected to be caused by BIOS. Even when enabled in the 1677 configuration, it is disabled at runtime. Enable it by 1678 setting "memory_corruption_check=1" on the kernel command 1679 line. By default it scans the low 64k of memory every 60 1680 seconds; see the memory_corruption_check_size and 1681 memory_corruption_check_period parameters in 1682 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1683 1684 When enabled with the default parameters, this option has 1685 almost no overhead, as it reserves a relatively small amount 1686 of memory and scans it infrequently. It both detects corruption 1687 and prevents it from affecting the running system. 1688 1689 It is, however, intended as a diagnostic tool; if repeatable 1690 BIOS-originated corruption always affects the same memory, 1691 you can use memmap= to prevent the kernel from using that 1692 memory. 1693 1694config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1695 bool "Set the default setting of memory_corruption_check" 1696 depends on X86_CHECK_BIOS_CORRUPTION 1697 default y 1698 help 1699 Set whether the default state of memory_corruption_check is 1700 on or off. 1701 1702config MATH_EMULATION 1703 bool 1704 depends on MODIFY_LDT_SYSCALL 1705 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1706 help 1707 Linux can emulate a math coprocessor (used for floating point 1708 operations) if you don't have one. 486DX and Pentium processors have 1709 a math coprocessor built in, 486SX and 386 do not, unless you added 1710 a 487DX or 387, respectively. (The messages during boot time can 1711 give you some hints here ["man dmesg"].) Everyone needs either a 1712 coprocessor or this emulation. 1713 1714 If you don't have a math coprocessor, you need to say Y here; if you 1715 say Y here even though you have a coprocessor, the coprocessor will 1716 be used nevertheless. (This behavior can be changed with the kernel 1717 command line option "no387", which comes handy if your coprocessor 1718 is broken. Try "man bootparam" or see the documentation of your boot 1719 loader (lilo or loadlin) about how to pass options to the kernel at 1720 boot time.) This means that it is a good idea to say Y here if you 1721 intend to use this kernel on different machines. 1722 1723 More information about the internals of the Linux math coprocessor 1724 emulation can be found in <file:arch/x86/math-emu/README>. 1725 1726 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1727 kernel, it won't hurt. 1728 1729config MTRR 1730 def_bool y 1731 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1732 help 1733 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1734 the Memory Type Range Registers (MTRRs) may be used to control 1735 processor access to memory ranges. This is most useful if you have 1736 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1737 allows bus write transfers to be combined into a larger transfer 1738 before bursting over the PCI/AGP bus. This can increase performance 1739 of image write operations 2.5 times or more. Saying Y here creates a 1740 /proc/mtrr file which may be used to manipulate your processor's 1741 MTRRs. Typically the X server should use this. 1742 1743 This code has a reasonably generic interface so that similar 1744 control registers on other processors can be easily supported 1745 as well: 1746 1747 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1748 Registers (ARRs) which provide a similar functionality to MTRRs. For 1749 these, the ARRs are used to emulate the MTRRs. 1750 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1751 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1752 write-combining. All of these processors are supported by this code 1753 and it makes sense to say Y here if you have one of them. 1754 1755 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1756 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1757 can lead to all sorts of problems, so it's good to say Y here. 1758 1759 You can safely say Y even if your machine doesn't have MTRRs, you'll 1760 just add about 9 KB to your kernel. 1761 1762 See <file:Documentation/x86/mtrr.rst> for more information. 1763 1764config MTRR_SANITIZER 1765 def_bool y 1766 prompt "MTRR cleanup support" 1767 depends on MTRR 1768 help 1769 Convert MTRR layout from continuous to discrete, so X drivers can 1770 add writeback entries. 1771 1772 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1773 The largest mtrr entry size for a continuous block can be set with 1774 mtrr_chunk_size. 1775 1776 If unsure, say Y. 1777 1778config MTRR_SANITIZER_ENABLE_DEFAULT 1779 int "MTRR cleanup enable value (0-1)" 1780 range 0 1 1781 default "0" 1782 depends on MTRR_SANITIZER 1783 help 1784 Enable mtrr cleanup default value 1785 1786config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1787 int "MTRR cleanup spare reg num (0-7)" 1788 range 0 7 1789 default "1" 1790 depends on MTRR_SANITIZER 1791 help 1792 mtrr cleanup spare entries default, it can be changed via 1793 mtrr_spare_reg_nr=N on the kernel command line. 1794 1795config X86_PAT 1796 def_bool y 1797 prompt "x86 PAT support" if EXPERT 1798 depends on MTRR 1799 help 1800 Use PAT attributes to setup page level cache control. 1801 1802 PATs are the modern equivalents of MTRRs and are much more 1803 flexible than MTRRs. 1804 1805 Say N here if you see bootup problems (boot crash, boot hang, 1806 spontaneous reboots) or a non-working video driver. 1807 1808 If unsure, say Y. 1809 1810config ARCH_USES_PG_UNCACHED 1811 def_bool y 1812 depends on X86_PAT 1813 1814config X86_UMIP 1815 def_bool y 1816 prompt "User Mode Instruction Prevention" if EXPERT 1817 help 1818 User Mode Instruction Prevention (UMIP) is a security feature in 1819 some x86 processors. If enabled, a general protection fault is 1820 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1821 executed in user mode. These instructions unnecessarily expose 1822 information about the hardware state. 1823 1824 The vast majority of applications do not use these instructions. 1825 For the very few that do, software emulation is provided in 1826 specific cases in protected and virtual-8086 modes. Emulated 1827 results are dummy. 1828 1829config CC_HAS_IBT 1830 # GCC >= 9 and binutils >= 2.29 1831 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1832 # Clang/LLVM >= 14 1833 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1834 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1835 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1836 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1837 $(as-instr,endbr64) 1838 1839config X86_KERNEL_IBT 1840 prompt "Indirect Branch Tracking" 1841 bool 1842 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1843 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1844 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1845 select OBJTOOL 1846 help 1847 Build the kernel with support for Indirect Branch Tracking, a 1848 hardware support course-grain forward-edge Control Flow Integrity 1849 protection. It enforces that all indirect calls must land on 1850 an ENDBR instruction, as such, the compiler will instrument the 1851 code with them to make this happen. 1852 1853 In addition to building the kernel with IBT, seal all functions that 1854 are not indirect call targets, avoiding them ever becoming one. 1855 1856 This requires LTO like objtool runs and will slow down the build. It 1857 does significantly reduce the number of ENDBR instructions in the 1858 kernel image. 1859 1860config X86_INTEL_MEMORY_PROTECTION_KEYS 1861 prompt "Memory Protection Keys" 1862 def_bool y 1863 # Note: only available in 64-bit mode 1864 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1865 select ARCH_USES_HIGH_VMA_FLAGS 1866 select ARCH_HAS_PKEYS 1867 help 1868 Memory Protection Keys provides a mechanism for enforcing 1869 page-based protections, but without requiring modification of the 1870 page tables when an application changes protection domains. 1871 1872 For details, see Documentation/core-api/protection-keys.rst 1873 1874 If unsure, say y. 1875 1876choice 1877 prompt "TSX enable mode" 1878 depends on CPU_SUP_INTEL 1879 default X86_INTEL_TSX_MODE_OFF 1880 help 1881 Intel's TSX (Transactional Synchronization Extensions) feature 1882 allows to optimize locking protocols through lock elision which 1883 can lead to a noticeable performance boost. 1884 1885 On the other hand it has been shown that TSX can be exploited 1886 to form side channel attacks (e.g. TAA) and chances are there 1887 will be more of those attacks discovered in the future. 1888 1889 Therefore TSX is not enabled by default (aka tsx=off). An admin 1890 might override this decision by tsx=on the command line parameter. 1891 Even with TSX enabled, the kernel will attempt to enable the best 1892 possible TAA mitigation setting depending on the microcode available 1893 for the particular machine. 1894 1895 This option allows to set the default tsx mode between tsx=on, =off 1896 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1897 details. 1898 1899 Say off if not sure, auto if TSX is in use but it should be used on safe 1900 platforms or on if TSX is in use and the security aspect of tsx is not 1901 relevant. 1902 1903config X86_INTEL_TSX_MODE_OFF 1904 bool "off" 1905 help 1906 TSX is disabled if possible - equals to tsx=off command line parameter. 1907 1908config X86_INTEL_TSX_MODE_ON 1909 bool "on" 1910 help 1911 TSX is always enabled on TSX capable HW - equals the tsx=on command 1912 line parameter. 1913 1914config X86_INTEL_TSX_MODE_AUTO 1915 bool "auto" 1916 help 1917 TSX is enabled on TSX capable HW that is believed to be safe against 1918 side channel attacks- equals the tsx=auto command line parameter. 1919endchoice 1920 1921config X86_SGX 1922 bool "Software Guard eXtensions (SGX)" 1923 depends on X86_64 && CPU_SUP_INTEL 1924 depends on CRYPTO=y 1925 depends on CRYPTO_SHA256=y 1926 select SRCU 1927 select MMU_NOTIFIER 1928 select NUMA_KEEP_MEMINFO if NUMA 1929 select XARRAY_MULTI 1930 help 1931 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1932 that can be used by applications to set aside private regions of code 1933 and data, referred to as enclaves. An enclave's private memory can 1934 only be accessed by code running within the enclave. Accesses from 1935 outside the enclave, including other enclaves, are disallowed by 1936 hardware. 1937 1938 If unsure, say N. 1939 1940config EFI 1941 bool "EFI runtime service support" 1942 depends on ACPI 1943 select UCS2_STRING 1944 select EFI_RUNTIME_WRAPPERS 1945 select ARCH_USE_MEMREMAP_PROT 1946 help 1947 This enables the kernel to use EFI runtime services that are 1948 available (such as the EFI variable services). 1949 1950 This option is only useful on systems that have EFI firmware. 1951 In addition, you should use the latest ELILO loader available 1952 at <http://elilo.sourceforge.net> in order to take advantage 1953 of EFI runtime services. However, even with this option, the 1954 resultant kernel should continue to boot on existing non-EFI 1955 platforms. 1956 1957config EFI_STUB 1958 bool "EFI stub support" 1959 depends on EFI 1960 depends on $(cc-option,-mabi=ms) || X86_32 1961 select RELOCATABLE 1962 help 1963 This kernel feature allows a bzImage to be loaded directly 1964 by EFI firmware without the use of a bootloader. 1965 1966 See Documentation/admin-guide/efi-stub.rst for more information. 1967 1968config EFI_MIXED 1969 bool "EFI mixed-mode support" 1970 depends on EFI_STUB && X86_64 1971 help 1972 Enabling this feature allows a 64-bit kernel to be booted 1973 on a 32-bit firmware, provided that your CPU supports 64-bit 1974 mode. 1975 1976 Note that it is not possible to boot a mixed-mode enabled 1977 kernel via the EFI boot stub - a bootloader that supports 1978 the EFI handover protocol must be used. 1979 1980 If unsure, say N. 1981 1982source "kernel/Kconfig.hz" 1983 1984config KEXEC 1985 bool "kexec system call" 1986 select KEXEC_CORE 1987 help 1988 kexec is a system call that implements the ability to shutdown your 1989 current kernel, and to start another kernel. It is like a reboot 1990 but it is independent of the system firmware. And like a reboot 1991 you can start any kernel with it, not just Linux. 1992 1993 The name comes from the similarity to the exec system call. 1994 1995 It is an ongoing process to be certain the hardware in a machine 1996 is properly shutdown, so do not be surprised if this code does not 1997 initially work for you. As of this writing the exact hardware 1998 interface is strongly in flux, so no good recommendation can be 1999 made. 2000 2001config KEXEC_FILE 2002 bool "kexec file based system call" 2003 select KEXEC_CORE 2004 select HAVE_IMA_KEXEC if IMA 2005 depends on X86_64 2006 depends on CRYPTO=y 2007 depends on CRYPTO_SHA256=y 2008 help 2009 This is new version of kexec system call. This system call is 2010 file based and takes file descriptors as system call argument 2011 for kernel and initramfs as opposed to list of segments as 2012 accepted by previous system call. 2013 2014config ARCH_HAS_KEXEC_PURGATORY 2015 def_bool KEXEC_FILE 2016 2017config KEXEC_SIG 2018 bool "Verify kernel signature during kexec_file_load() syscall" 2019 depends on KEXEC_FILE 2020 help 2021 2022 This option makes the kexec_file_load() syscall check for a valid 2023 signature of the kernel image. The image can still be loaded without 2024 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2025 there's a signature that we can check, then it must be valid. 2026 2027 In addition to this option, you need to enable signature 2028 verification for the corresponding kernel image type being 2029 loaded in order for this to work. 2030 2031config KEXEC_SIG_FORCE 2032 bool "Require a valid signature in kexec_file_load() syscall" 2033 depends on KEXEC_SIG 2034 help 2035 This option makes kernel signature verification mandatory for 2036 the kexec_file_load() syscall. 2037 2038config KEXEC_BZIMAGE_VERIFY_SIG 2039 bool "Enable bzImage signature verification support" 2040 depends on KEXEC_SIG 2041 depends on SIGNED_PE_FILE_VERIFICATION 2042 select SYSTEM_TRUSTED_KEYRING 2043 help 2044 Enable bzImage signature verification support. 2045 2046config CRASH_DUMP 2047 bool "kernel crash dumps" 2048 depends on X86_64 || (X86_32 && HIGHMEM) 2049 help 2050 Generate crash dump after being started by kexec. 2051 This should be normally only set in special crash dump kernels 2052 which are loaded in the main kernel with kexec-tools into 2053 a specially reserved region and then later executed after 2054 a crash by kdump/kexec. The crash dump kernel must be compiled 2055 to a memory address not used by the main kernel or BIOS using 2056 PHYSICAL_START, or it must be built as a relocatable image 2057 (CONFIG_RELOCATABLE=y). 2058 For more details see Documentation/admin-guide/kdump/kdump.rst 2059 2060config KEXEC_JUMP 2061 bool "kexec jump" 2062 depends on KEXEC && HIBERNATION 2063 help 2064 Jump between original kernel and kexeced kernel and invoke 2065 code in physical address mode via KEXEC 2066 2067config PHYSICAL_START 2068 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2069 default "0x1000000" 2070 help 2071 This gives the physical address where the kernel is loaded. 2072 2073 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2074 bzImage will decompress itself to above physical address and 2075 run from there. Otherwise, bzImage will run from the address where 2076 it has been loaded by the boot loader and will ignore above physical 2077 address. 2078 2079 In normal kdump cases one does not have to set/change this option 2080 as now bzImage can be compiled as a completely relocatable image 2081 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2082 address. This option is mainly useful for the folks who don't want 2083 to use a bzImage for capturing the crash dump and want to use a 2084 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2085 to be specifically compiled to run from a specific memory area 2086 (normally a reserved region) and this option comes handy. 2087 2088 So if you are using bzImage for capturing the crash dump, 2089 leave the value here unchanged to 0x1000000 and set 2090 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2091 for capturing the crash dump change this value to start of 2092 the reserved region. In other words, it can be set based on 2093 the "X" value as specified in the "crashkernel=YM@XM" 2094 command line boot parameter passed to the panic-ed 2095 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2096 for more details about crash dumps. 2097 2098 Usage of bzImage for capturing the crash dump is recommended as 2099 one does not have to build two kernels. Same kernel can be used 2100 as production kernel and capture kernel. Above option should have 2101 gone away after relocatable bzImage support is introduced. But it 2102 is present because there are users out there who continue to use 2103 vmlinux for dump capture. This option should go away down the 2104 line. 2105 2106 Don't change this unless you know what you are doing. 2107 2108config RELOCATABLE 2109 bool "Build a relocatable kernel" 2110 default y 2111 help 2112 This builds a kernel image that retains relocation information 2113 so it can be loaded someplace besides the default 1MB. 2114 The relocations tend to make the kernel binary about 10% larger, 2115 but are discarded at runtime. 2116 2117 One use is for the kexec on panic case where the recovery kernel 2118 must live at a different physical address than the primary 2119 kernel. 2120 2121 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2122 it has been loaded at and the compile time physical address 2123 (CONFIG_PHYSICAL_START) is used as the minimum location. 2124 2125config RANDOMIZE_BASE 2126 bool "Randomize the address of the kernel image (KASLR)" 2127 depends on RELOCATABLE 2128 default y 2129 help 2130 In support of Kernel Address Space Layout Randomization (KASLR), 2131 this randomizes the physical address at which the kernel image 2132 is decompressed and the virtual address where the kernel 2133 image is mapped, as a security feature that deters exploit 2134 attempts relying on knowledge of the location of kernel 2135 code internals. 2136 2137 On 64-bit, the kernel physical and virtual addresses are 2138 randomized separately. The physical address will be anywhere 2139 between 16MB and the top of physical memory (up to 64TB). The 2140 virtual address will be randomized from 16MB up to 1GB (9 bits 2141 of entropy). Note that this also reduces the memory space 2142 available to kernel modules from 1.5GB to 1GB. 2143 2144 On 32-bit, the kernel physical and virtual addresses are 2145 randomized together. They will be randomized from 16MB up to 2146 512MB (8 bits of entropy). 2147 2148 Entropy is generated using the RDRAND instruction if it is 2149 supported. If RDTSC is supported, its value is mixed into 2150 the entropy pool as well. If neither RDRAND nor RDTSC are 2151 supported, then entropy is read from the i8254 timer. The 2152 usable entropy is limited by the kernel being built using 2153 2GB addressing, and that PHYSICAL_ALIGN must be at a 2154 minimum of 2MB. As a result, only 10 bits of entropy are 2155 theoretically possible, but the implementations are further 2156 limited due to memory layouts. 2157 2158 If unsure, say Y. 2159 2160# Relocation on x86 needs some additional build support 2161config X86_NEED_RELOCS 2162 def_bool y 2163 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2164 2165config PHYSICAL_ALIGN 2166 hex "Alignment value to which kernel should be aligned" 2167 default "0x200000" 2168 range 0x2000 0x1000000 if X86_32 2169 range 0x200000 0x1000000 if X86_64 2170 help 2171 This value puts the alignment restrictions on physical address 2172 where kernel is loaded and run from. Kernel is compiled for an 2173 address which meets above alignment restriction. 2174 2175 If bootloader loads the kernel at a non-aligned address and 2176 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2177 address aligned to above value and run from there. 2178 2179 If bootloader loads the kernel at a non-aligned address and 2180 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2181 load address and decompress itself to the address it has been 2182 compiled for and run from there. The address for which kernel is 2183 compiled already meets above alignment restrictions. Hence the 2184 end result is that kernel runs from a physical address meeting 2185 above alignment restrictions. 2186 2187 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2188 this value must be a multiple of 0x200000. 2189 2190 Don't change this unless you know what you are doing. 2191 2192config DYNAMIC_MEMORY_LAYOUT 2193 bool 2194 help 2195 This option makes base addresses of vmalloc and vmemmap as well as 2196 __PAGE_OFFSET movable during boot. 2197 2198config RANDOMIZE_MEMORY 2199 bool "Randomize the kernel memory sections" 2200 depends on X86_64 2201 depends on RANDOMIZE_BASE 2202 select DYNAMIC_MEMORY_LAYOUT 2203 default RANDOMIZE_BASE 2204 help 2205 Randomizes the base virtual address of kernel memory sections 2206 (physical memory mapping, vmalloc & vmemmap). This security feature 2207 makes exploits relying on predictable memory locations less reliable. 2208 2209 The order of allocations remains unchanged. Entropy is generated in 2210 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2211 configuration have in average 30,000 different possible virtual 2212 addresses for each memory section. 2213 2214 If unsure, say Y. 2215 2216config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2217 hex "Physical memory mapping padding" if EXPERT 2218 depends on RANDOMIZE_MEMORY 2219 default "0xa" if MEMORY_HOTPLUG 2220 default "0x0" 2221 range 0x1 0x40 if MEMORY_HOTPLUG 2222 range 0x0 0x40 2223 help 2224 Define the padding in terabytes added to the existing physical 2225 memory size during kernel memory randomization. It is useful 2226 for memory hotplug support but reduces the entropy available for 2227 address randomization. 2228 2229 If unsure, leave at the default value. 2230 2231config HOTPLUG_CPU 2232 def_bool y 2233 depends on SMP 2234 2235config BOOTPARAM_HOTPLUG_CPU0 2236 bool "Set default setting of cpu0_hotpluggable" 2237 depends on HOTPLUG_CPU 2238 help 2239 Set whether default state of cpu0_hotpluggable is on or off. 2240 2241 Say Y here to enable CPU0 hotplug by default. If this switch 2242 is turned on, there is no need to give cpu0_hotplug kernel 2243 parameter and the CPU0 hotplug feature is enabled by default. 2244 2245 Please note: there are two known CPU0 dependencies if you want 2246 to enable the CPU0 hotplug feature either by this switch or by 2247 cpu0_hotplug kernel parameter. 2248 2249 First, resume from hibernate or suspend always starts from CPU0. 2250 So hibernate and suspend are prevented if CPU0 is offline. 2251 2252 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2253 offline if any interrupt can not migrate out of CPU0. There may 2254 be other CPU0 dependencies. 2255 2256 Please make sure the dependencies are under your control before 2257 you enable this feature. 2258 2259 Say N if you don't want to enable CPU0 hotplug feature by default. 2260 You still can enable the CPU0 hotplug feature at boot by kernel 2261 parameter cpu0_hotplug. 2262 2263config DEBUG_HOTPLUG_CPU0 2264 def_bool n 2265 prompt "Debug CPU0 hotplug" 2266 depends on HOTPLUG_CPU 2267 help 2268 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2269 soon as possible and boots up userspace with CPU0 offlined. User 2270 can online CPU0 back after boot time. 2271 2272 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2273 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2274 compilation or giving cpu0_hotplug kernel parameter at boot. 2275 2276 If unsure, say N. 2277 2278config COMPAT_VDSO 2279 def_bool n 2280 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2281 depends on COMPAT_32 2282 help 2283 Certain buggy versions of glibc will crash if they are 2284 presented with a 32-bit vDSO that is not mapped at the address 2285 indicated in its segment table. 2286 2287 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2288 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2289 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2290 the only released version with the bug, but OpenSUSE 9 2291 contains a buggy "glibc 2.3.2". 2292 2293 The symptom of the bug is that everything crashes on startup, saying: 2294 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2295 2296 Saying Y here changes the default value of the vdso32 boot 2297 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2298 This works around the glibc bug but hurts performance. 2299 2300 If unsure, say N: if you are compiling your own kernel, you 2301 are unlikely to be using a buggy version of glibc. 2302 2303choice 2304 prompt "vsyscall table for legacy applications" 2305 depends on X86_64 2306 default LEGACY_VSYSCALL_XONLY 2307 help 2308 Legacy user code that does not know how to find the vDSO expects 2309 to be able to issue three syscalls by calling fixed addresses in 2310 kernel space. Since this location is not randomized with ASLR, 2311 it can be used to assist security vulnerability exploitation. 2312 2313 This setting can be changed at boot time via the kernel command 2314 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2315 is deprecated and can only be enabled using the kernel command 2316 line. 2317 2318 On a system with recent enough glibc (2.14 or newer) and no 2319 static binaries, you can say None without a performance penalty 2320 to improve security. 2321 2322 If unsure, select "Emulate execution only". 2323 2324 config LEGACY_VSYSCALL_XONLY 2325 bool "Emulate execution only" 2326 help 2327 The kernel traps and emulates calls into the fixed vsyscall 2328 address mapping and does not allow reads. This 2329 configuration is recommended when userspace might use the 2330 legacy vsyscall area but support for legacy binary 2331 instrumentation of legacy code is not needed. It mitigates 2332 certain uses of the vsyscall area as an ASLR-bypassing 2333 buffer. 2334 2335 config LEGACY_VSYSCALL_NONE 2336 bool "None" 2337 help 2338 There will be no vsyscall mapping at all. This will 2339 eliminate any risk of ASLR bypass due to the vsyscall 2340 fixed address mapping. Attempts to use the vsyscalls 2341 will be reported to dmesg, so that either old or 2342 malicious userspace programs can be identified. 2343 2344endchoice 2345 2346config CMDLINE_BOOL 2347 bool "Built-in kernel command line" 2348 help 2349 Allow for specifying boot arguments to the kernel at 2350 build time. On some systems (e.g. embedded ones), it is 2351 necessary or convenient to provide some or all of the 2352 kernel boot arguments with the kernel itself (that is, 2353 to not rely on the boot loader to provide them.) 2354 2355 To compile command line arguments into the kernel, 2356 set this option to 'Y', then fill in the 2357 boot arguments in CONFIG_CMDLINE. 2358 2359 Systems with fully functional boot loaders (i.e. non-embedded) 2360 should leave this option set to 'N'. 2361 2362config CMDLINE 2363 string "Built-in kernel command string" 2364 depends on CMDLINE_BOOL 2365 default "" 2366 help 2367 Enter arguments here that should be compiled into the kernel 2368 image and used at boot time. If the boot loader provides a 2369 command line at boot time, it is appended to this string to 2370 form the full kernel command line, when the system boots. 2371 2372 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2373 change this behavior. 2374 2375 In most cases, the command line (whether built-in or provided 2376 by the boot loader) should specify the device for the root 2377 file system. 2378 2379config CMDLINE_OVERRIDE 2380 bool "Built-in command line overrides boot loader arguments" 2381 depends on CMDLINE_BOOL && CMDLINE != "" 2382 help 2383 Set this option to 'Y' to have the kernel ignore the boot loader 2384 command line, and use ONLY the built-in command line. 2385 2386 This is used to work around broken boot loaders. This should 2387 be set to 'N' under normal conditions. 2388 2389config MODIFY_LDT_SYSCALL 2390 bool "Enable the LDT (local descriptor table)" if EXPERT 2391 default y 2392 help 2393 Linux can allow user programs to install a per-process x86 2394 Local Descriptor Table (LDT) using the modify_ldt(2) system 2395 call. This is required to run 16-bit or segmented code such as 2396 DOSEMU or some Wine programs. It is also used by some very old 2397 threading libraries. 2398 2399 Enabling this feature adds a small amount of overhead to 2400 context switches and increases the low-level kernel attack 2401 surface. Disabling it removes the modify_ldt(2) system call. 2402 2403 Saying 'N' here may make sense for embedded or server kernels. 2404 2405config STRICT_SIGALTSTACK_SIZE 2406 bool "Enforce strict size checking for sigaltstack" 2407 depends on DYNAMIC_SIGFRAME 2408 help 2409 For historical reasons MINSIGSTKSZ is a constant which became 2410 already too small with AVX512 support. Add a mechanism to 2411 enforce strict checking of the sigaltstack size against the 2412 real size of the FPU frame. This option enables the check 2413 by default. It can also be controlled via the kernel command 2414 line option 'strict_sas_size' independent of this config 2415 switch. Enabling it might break existing applications which 2416 allocate a too small sigaltstack but 'work' because they 2417 never get a signal delivered. 2418 2419 Say 'N' unless you want to really enforce this check. 2420 2421source "kernel/livepatch/Kconfig" 2422 2423endmenu 2424 2425config CC_HAS_SLS 2426 def_bool $(cc-option,-mharden-sls=all) 2427 2428config CC_HAS_RETURN_THUNK 2429 def_bool $(cc-option,-mfunction-return=thunk-extern) 2430 2431menuconfig SPECULATION_MITIGATIONS 2432 bool "Mitigations for speculative execution vulnerabilities" 2433 default y 2434 help 2435 Say Y here to enable options which enable mitigations for 2436 speculative execution hardware vulnerabilities. 2437 2438 If you say N, all mitigations will be disabled. You really 2439 should know what you are doing to say so. 2440 2441if SPECULATION_MITIGATIONS 2442 2443config PAGE_TABLE_ISOLATION 2444 bool "Remove the kernel mapping in user mode" 2445 default y 2446 depends on (X86_64 || X86_PAE) 2447 help 2448 This feature reduces the number of hardware side channels by 2449 ensuring that the majority of kernel addresses are not mapped 2450 into userspace. 2451 2452 See Documentation/x86/pti.rst for more details. 2453 2454config RETPOLINE 2455 bool "Avoid speculative indirect branches in kernel" 2456 select OBJTOOL if HAVE_OBJTOOL 2457 default y 2458 help 2459 Compile kernel with the retpoline compiler options to guard against 2460 kernel-to-user data leaks by avoiding speculative indirect 2461 branches. Requires a compiler with -mindirect-branch=thunk-extern 2462 support for full protection. The kernel may run slower. 2463 2464config RETHUNK 2465 bool "Enable return-thunks" 2466 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2467 select OBJTOOL if HAVE_OBJTOOL 2468 default y if X86_64 2469 help 2470 Compile the kernel with the return-thunks compiler option to guard 2471 against kernel-to-user data leaks by avoiding return speculation. 2472 Requires a compiler with -mfunction-return=thunk-extern 2473 support for full protection. The kernel may run slower. 2474 2475config CPU_UNRET_ENTRY 2476 bool "Enable UNRET on kernel entry" 2477 depends on CPU_SUP_AMD && RETHUNK && X86_64 2478 default y 2479 help 2480 Compile the kernel with support for the retbleed=unret mitigation. 2481 2482config CPU_IBPB_ENTRY 2483 bool "Enable IBPB on kernel entry" 2484 depends on CPU_SUP_AMD && X86_64 2485 default y 2486 help 2487 Compile the kernel with support for the retbleed=ibpb mitigation. 2488 2489config CPU_IBRS_ENTRY 2490 bool "Enable IBRS on kernel entry" 2491 depends on CPU_SUP_INTEL && X86_64 2492 default y 2493 help 2494 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2495 This mitigates both spectre_v2 and retbleed at great cost to 2496 performance. 2497 2498config SLS 2499 bool "Mitigate Straight-Line-Speculation" 2500 depends on CC_HAS_SLS && X86_64 2501 select OBJTOOL if HAVE_OBJTOOL 2502 default n 2503 help 2504 Compile the kernel with straight-line-speculation options to guard 2505 against straight line speculation. The kernel image might be slightly 2506 larger. 2507 2508endif 2509 2510config ARCH_HAS_ADD_PAGES 2511 def_bool y 2512 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2513 2514config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2515 def_bool y 2516 2517menu "Power management and ACPI options" 2518 2519config ARCH_HIBERNATION_HEADER 2520 def_bool y 2521 depends on HIBERNATION 2522 2523source "kernel/power/Kconfig" 2524 2525source "drivers/acpi/Kconfig" 2526 2527config X86_APM_BOOT 2528 def_bool y 2529 depends on APM 2530 2531menuconfig APM 2532 tristate "APM (Advanced Power Management) BIOS support" 2533 depends on X86_32 && PM_SLEEP 2534 help 2535 APM is a BIOS specification for saving power using several different 2536 techniques. This is mostly useful for battery powered laptops with 2537 APM compliant BIOSes. If you say Y here, the system time will be 2538 reset after a RESUME operation, the /proc/apm device will provide 2539 battery status information, and user-space programs will receive 2540 notification of APM "events" (e.g. battery status change). 2541 2542 If you select "Y" here, you can disable actual use of the APM 2543 BIOS by passing the "apm=off" option to the kernel at boot time. 2544 2545 Note that the APM support is almost completely disabled for 2546 machines with more than one CPU. 2547 2548 In order to use APM, you will need supporting software. For location 2549 and more information, read <file:Documentation/power/apm-acpi.rst> 2550 and the Battery Powered Linux mini-HOWTO, available from 2551 <http://www.tldp.org/docs.html#howto>. 2552 2553 This driver does not spin down disk drives (see the hdparm(8) 2554 manpage ("man 8 hdparm") for that), and it doesn't turn off 2555 VESA-compliant "green" monitors. 2556 2557 This driver does not support the TI 4000M TravelMate and the ACER 2558 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2559 desktop machines also don't have compliant BIOSes, and this driver 2560 may cause those machines to panic during the boot phase. 2561 2562 Generally, if you don't have a battery in your machine, there isn't 2563 much point in using this driver and you should say N. If you get 2564 random kernel OOPSes or reboots that don't seem to be related to 2565 anything, try disabling/enabling this option (or disabling/enabling 2566 APM in your BIOS). 2567 2568 Some other things you should try when experiencing seemingly random, 2569 "weird" problems: 2570 2571 1) make sure that you have enough swap space and that it is 2572 enabled. 2573 2) pass the "no-hlt" option to the kernel 2574 3) switch on floating point emulation in the kernel and pass 2575 the "no387" option to the kernel 2576 4) pass the "floppy=nodma" option to the kernel 2577 5) pass the "mem=4M" option to the kernel (thereby disabling 2578 all but the first 4 MB of RAM) 2579 6) make sure that the CPU is not over clocked. 2580 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2581 8) disable the cache from your BIOS settings 2582 9) install a fan for the video card or exchange video RAM 2583 10) install a better fan for the CPU 2584 11) exchange RAM chips 2585 12) exchange the motherboard. 2586 2587 To compile this driver as a module, choose M here: the 2588 module will be called apm. 2589 2590if APM 2591 2592config APM_IGNORE_USER_SUSPEND 2593 bool "Ignore USER SUSPEND" 2594 help 2595 This option will ignore USER SUSPEND requests. On machines with a 2596 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2597 series notebooks, it is necessary to say Y because of a BIOS bug. 2598 2599config APM_DO_ENABLE 2600 bool "Enable PM at boot time" 2601 help 2602 Enable APM features at boot time. From page 36 of the APM BIOS 2603 specification: "When disabled, the APM BIOS does not automatically 2604 power manage devices, enter the Standby State, enter the Suspend 2605 State, or take power saving steps in response to CPU Idle calls." 2606 This driver will make CPU Idle calls when Linux is idle (unless this 2607 feature is turned off -- see "Do CPU IDLE calls", below). This 2608 should always save battery power, but more complicated APM features 2609 will be dependent on your BIOS implementation. You may need to turn 2610 this option off if your computer hangs at boot time when using APM 2611 support, or if it beeps continuously instead of suspending. Turn 2612 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2613 T400CDT. This is off by default since most machines do fine without 2614 this feature. 2615 2616config APM_CPU_IDLE 2617 depends on CPU_IDLE 2618 bool "Make CPU Idle calls when idle" 2619 help 2620 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2621 On some machines, this can activate improved power savings, such as 2622 a slowed CPU clock rate, when the machine is idle. These idle calls 2623 are made after the idle loop has run for some length of time (e.g., 2624 333 mS). On some machines, this will cause a hang at boot time or 2625 whenever the CPU becomes idle. (On machines with more than one CPU, 2626 this option does nothing.) 2627 2628config APM_DISPLAY_BLANK 2629 bool "Enable console blanking using APM" 2630 help 2631 Enable console blanking using the APM. Some laptops can use this to 2632 turn off the LCD backlight when the screen blanker of the Linux 2633 virtual console blanks the screen. Note that this is only used by 2634 the virtual console screen blanker, and won't turn off the backlight 2635 when using the X Window system. This also doesn't have anything to 2636 do with your VESA-compliant power-saving monitor. Further, this 2637 option doesn't work for all laptops -- it might not turn off your 2638 backlight at all, or it might print a lot of errors to the console, 2639 especially if you are using gpm. 2640 2641config APM_ALLOW_INTS 2642 bool "Allow interrupts during APM BIOS calls" 2643 help 2644 Normally we disable external interrupts while we are making calls to 2645 the APM BIOS as a measure to lessen the effects of a badly behaving 2646 BIOS implementation. The BIOS should reenable interrupts if it 2647 needs to. Unfortunately, some BIOSes do not -- especially those in 2648 many of the newer IBM Thinkpads. If you experience hangs when you 2649 suspend, try setting this to Y. Otherwise, say N. 2650 2651endif # APM 2652 2653source "drivers/cpufreq/Kconfig" 2654 2655source "drivers/cpuidle/Kconfig" 2656 2657source "drivers/idle/Kconfig" 2658 2659endmenu 2660 2661menu "Bus options (PCI etc.)" 2662 2663choice 2664 prompt "PCI access mode" 2665 depends on X86_32 && PCI 2666 default PCI_GOANY 2667 help 2668 On PCI systems, the BIOS can be used to detect the PCI devices and 2669 determine their configuration. However, some old PCI motherboards 2670 have BIOS bugs and may crash if this is done. Also, some embedded 2671 PCI-based systems don't have any BIOS at all. Linux can also try to 2672 detect the PCI hardware directly without using the BIOS. 2673 2674 With this option, you can specify how Linux should detect the 2675 PCI devices. If you choose "BIOS", the BIOS will be used, 2676 if you choose "Direct", the BIOS won't be used, and if you 2677 choose "MMConfig", then PCI Express MMCONFIG will be used. 2678 If you choose "Any", the kernel will try MMCONFIG, then the 2679 direct access method and falls back to the BIOS if that doesn't 2680 work. If unsure, go with the default, which is "Any". 2681 2682config PCI_GOBIOS 2683 bool "BIOS" 2684 2685config PCI_GOMMCONFIG 2686 bool "MMConfig" 2687 2688config PCI_GODIRECT 2689 bool "Direct" 2690 2691config PCI_GOOLPC 2692 bool "OLPC XO-1" 2693 depends on OLPC 2694 2695config PCI_GOANY 2696 bool "Any" 2697 2698endchoice 2699 2700config PCI_BIOS 2701 def_bool y 2702 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2703 2704# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2705config PCI_DIRECT 2706 def_bool y 2707 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2708 2709config PCI_MMCONFIG 2710 bool "Support mmconfig PCI config space access" if X86_64 2711 default y 2712 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2713 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2714 2715config PCI_OLPC 2716 def_bool y 2717 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2718 2719config PCI_XEN 2720 def_bool y 2721 depends on PCI && XEN 2722 2723config MMCONF_FAM10H 2724 def_bool y 2725 depends on X86_64 && PCI_MMCONFIG && ACPI 2726 2727config PCI_CNB20LE_QUIRK 2728 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2729 depends on PCI 2730 help 2731 Read the PCI windows out of the CNB20LE host bridge. This allows 2732 PCI hotplug to work on systems with the CNB20LE chipset which do 2733 not have ACPI. 2734 2735 There's no public spec for this chipset, and this functionality 2736 is known to be incomplete. 2737 2738 You should say N unless you know you need this. 2739 2740config ISA_BUS 2741 bool "ISA bus support on modern systems" if EXPERT 2742 help 2743 Expose ISA bus device drivers and options available for selection and 2744 configuration. Enable this option if your target machine has an ISA 2745 bus. ISA is an older system, displaced by PCI and newer bus 2746 architectures -- if your target machine is modern, it probably does 2747 not have an ISA bus. 2748 2749 If unsure, say N. 2750 2751# x86_64 have no ISA slots, but can have ISA-style DMA. 2752config ISA_DMA_API 2753 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2754 default y 2755 help 2756 Enables ISA-style DMA support for devices requiring such controllers. 2757 If unsure, say Y. 2758 2759if X86_32 2760 2761config ISA 2762 bool "ISA support" 2763 help 2764 Find out whether you have ISA slots on your motherboard. ISA is the 2765 name of a bus system, i.e. the way the CPU talks to the other stuff 2766 inside your box. Other bus systems are PCI, EISA, MicroChannel 2767 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2768 newer boards don't support it. If you have ISA, say Y, otherwise N. 2769 2770config SCx200 2771 tristate "NatSemi SCx200 support" 2772 help 2773 This provides basic support for National Semiconductor's 2774 (now AMD's) Geode processors. The driver probes for the 2775 PCI-IDs of several on-chip devices, so its a good dependency 2776 for other scx200_* drivers. 2777 2778 If compiled as a module, the driver is named scx200. 2779 2780config SCx200HR_TIMER 2781 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2782 depends on SCx200 2783 default y 2784 help 2785 This driver provides a clocksource built upon the on-chip 2786 27MHz high-resolution timer. Its also a workaround for 2787 NSC Geode SC-1100's buggy TSC, which loses time when the 2788 processor goes idle (as is done by the scheduler). The 2789 other workaround is idle=poll boot option. 2790 2791config OLPC 2792 bool "One Laptop Per Child support" 2793 depends on !X86_PAE 2794 select GPIOLIB 2795 select OF 2796 select OF_PROMTREE 2797 select IRQ_DOMAIN 2798 select OLPC_EC 2799 help 2800 Add support for detecting the unique features of the OLPC 2801 XO hardware. 2802 2803config OLPC_XO1_PM 2804 bool "OLPC XO-1 Power Management" 2805 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2806 help 2807 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2808 2809config OLPC_XO1_RTC 2810 bool "OLPC XO-1 Real Time Clock" 2811 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2812 help 2813 Add support for the XO-1 real time clock, which can be used as a 2814 programmable wakeup source. 2815 2816config OLPC_XO1_SCI 2817 bool "OLPC XO-1 SCI extras" 2818 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2819 depends on INPUT=y 2820 select POWER_SUPPLY 2821 help 2822 Add support for SCI-based features of the OLPC XO-1 laptop: 2823 - EC-driven system wakeups 2824 - Power button 2825 - Ebook switch 2826 - Lid switch 2827 - AC adapter status updates 2828 - Battery status updates 2829 2830config OLPC_XO15_SCI 2831 bool "OLPC XO-1.5 SCI extras" 2832 depends on OLPC && ACPI 2833 select POWER_SUPPLY 2834 help 2835 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2836 - EC-driven system wakeups 2837 - AC adapter status updates 2838 - Battery status updates 2839 2840config ALIX 2841 bool "PCEngines ALIX System Support (LED setup)" 2842 select GPIOLIB 2843 help 2844 This option enables system support for the PCEngines ALIX. 2845 At present this just sets up LEDs for GPIO control on 2846 ALIX2/3/6 boards. However, other system specific setup should 2847 get added here. 2848 2849 Note: You must still enable the drivers for GPIO and LED support 2850 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2851 2852 Note: You have to set alix.force=1 for boards with Award BIOS. 2853 2854config NET5501 2855 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2856 select GPIOLIB 2857 help 2858 This option enables system support for the Soekris Engineering net5501. 2859 2860config GEOS 2861 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2862 select GPIOLIB 2863 depends on DMI 2864 help 2865 This option enables system support for the Traverse Technologies GEOS. 2866 2867config TS5500 2868 bool "Technologic Systems TS-5500 platform support" 2869 depends on MELAN 2870 select CHECK_SIGNATURE 2871 select NEW_LEDS 2872 select LEDS_CLASS 2873 help 2874 This option enables system support for the Technologic Systems TS-5500. 2875 2876endif # X86_32 2877 2878config AMD_NB 2879 def_bool y 2880 depends on CPU_SUP_AMD && PCI 2881 2882endmenu 2883 2884menu "Binary Emulations" 2885 2886config IA32_EMULATION 2887 bool "IA32 Emulation" 2888 depends on X86_64 2889 select ARCH_WANT_OLD_COMPAT_IPC 2890 select BINFMT_ELF 2891 select COMPAT_OLD_SIGACTION 2892 help 2893 Include code to run legacy 32-bit programs under a 2894 64-bit kernel. You should likely turn this on, unless you're 2895 100% sure that you don't have any 32-bit programs left. 2896 2897config X86_X32_ABI 2898 bool "x32 ABI for 64-bit mode" 2899 depends on X86_64 2900 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2901 # compressed debug sections to x86_x32 properly: 2902 # https://github.com/ClangBuiltLinux/linux/issues/514 2903 # https://github.com/ClangBuiltLinux/linux/issues/1141 2904 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 2905 help 2906 Include code to run binaries for the x32 native 32-bit ABI 2907 for 64-bit processors. An x32 process gets access to the 2908 full 64-bit register file and wide data path while leaving 2909 pointers at 32 bits for smaller memory footprint. 2910 2911config COMPAT_32 2912 def_bool y 2913 depends on IA32_EMULATION || X86_32 2914 select HAVE_UID16 2915 select OLD_SIGSUSPEND3 2916 2917config COMPAT 2918 def_bool y 2919 depends on IA32_EMULATION || X86_X32_ABI 2920 2921config COMPAT_FOR_U64_ALIGNMENT 2922 def_bool y 2923 depends on COMPAT 2924 2925endmenu 2926 2927config HAVE_ATOMIC_IOMAP 2928 def_bool y 2929 depends on X86_32 2930 2931source "arch/x86/kvm/Kconfig" 2932 2933source "arch/x86/Kconfig.assembler" 2934