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 # Word-size accesses may read uninitialized data past the trailing \0 133 # in strings and cause false KMSAN reports. 134 select DCACHE_WORD_ACCESS if !KMSAN 135 select DYNAMIC_SIGFRAME 136 select EDAC_ATOMIC_SCRUB 137 select EDAC_SUPPORT 138 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 139 select GENERIC_CLOCKEVENTS_MIN_ADJUST 140 select GENERIC_CMOS_UPDATE 141 select GENERIC_CPU_AUTOPROBE 142 select GENERIC_CPU_VULNERABILITIES 143 select GENERIC_EARLY_IOREMAP 144 select GENERIC_ENTRY 145 select GENERIC_IOMAP 146 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 147 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 148 select GENERIC_IRQ_MIGRATION if SMP 149 select GENERIC_IRQ_PROBE 150 select GENERIC_IRQ_RESERVATION_MODE 151 select GENERIC_IRQ_SHOW 152 select GENERIC_PENDING_IRQ if SMP 153 select GENERIC_PTDUMP 154 select GENERIC_SMP_IDLE_THREAD 155 select GENERIC_TIME_VSYSCALL 156 select GENERIC_GETTIMEOFDAY 157 select GENERIC_VDSO_TIME_NS 158 select GUP_GET_PTE_LOW_HIGH if X86_PAE 159 select HARDIRQS_SW_RESEND 160 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 161 select HAVE_ACPI_APEI if ACPI 162 select HAVE_ACPI_APEI_NMI if ACPI 163 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 164 select HAVE_ARCH_AUDITSYSCALL 165 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 166 select HAVE_ARCH_HUGE_VMALLOC if X86_64 167 select HAVE_ARCH_JUMP_LABEL 168 select HAVE_ARCH_JUMP_LABEL_RELATIVE 169 select HAVE_ARCH_KASAN if X86_64 170 select HAVE_ARCH_KASAN_VMALLOC if X86_64 171 select HAVE_ARCH_KFENCE 172 select HAVE_ARCH_KMSAN if X86_64 173 select HAVE_ARCH_KGDB 174 select HAVE_ARCH_MMAP_RND_BITS if MMU 175 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 176 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 177 select HAVE_ARCH_PREL32_RELOCATIONS 178 select HAVE_ARCH_SECCOMP_FILTER 179 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 180 select HAVE_ARCH_STACKLEAK 181 select HAVE_ARCH_TRACEHOOK 182 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 183 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 184 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 185 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 186 select HAVE_ARCH_VMAP_STACK if X86_64 187 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 188 select HAVE_ARCH_WITHIN_STACK_FRAMES 189 select HAVE_ASM_MODVERSIONS 190 select HAVE_CMPXCHG_DOUBLE 191 select HAVE_CMPXCHG_LOCAL 192 select HAVE_CONTEXT_TRACKING_USER if X86_64 193 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 194 select HAVE_C_RECORDMCOUNT 195 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 196 select HAVE_BUILDTIME_MCOUNT_SORT 197 select HAVE_DEBUG_KMEMLEAK 198 select HAVE_DMA_CONTIGUOUS 199 select HAVE_DYNAMIC_FTRACE 200 select HAVE_DYNAMIC_FTRACE_WITH_REGS 201 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 202 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 203 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 204 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 205 select HAVE_EBPF_JIT 206 select HAVE_EFFICIENT_UNALIGNED_ACCESS 207 select HAVE_EISA 208 select HAVE_EXIT_THREAD 209 select HAVE_FAST_GUP 210 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 211 select HAVE_FTRACE_MCOUNT_RECORD 212 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 213 select HAVE_FUNCTION_TRACER 214 select HAVE_GCC_PLUGINS 215 select HAVE_HW_BREAKPOINT 216 select HAVE_IOREMAP_PROT 217 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 218 select HAVE_IRQ_TIME_ACCOUNTING 219 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 220 select HAVE_KERNEL_BZIP2 221 select HAVE_KERNEL_GZIP 222 select HAVE_KERNEL_LZ4 223 select HAVE_KERNEL_LZMA 224 select HAVE_KERNEL_LZO 225 select HAVE_KERNEL_XZ 226 select HAVE_KERNEL_ZSTD 227 select HAVE_KPROBES 228 select HAVE_KPROBES_ON_FTRACE 229 select HAVE_FUNCTION_ERROR_INJECTION 230 select HAVE_KRETPROBES 231 select HAVE_RETHOOK 232 select HAVE_KVM 233 select HAVE_LIVEPATCH if X86_64 234 select HAVE_MIXED_BREAKPOINTS_REGS 235 select HAVE_MOD_ARCH_SPECIFIC 236 select HAVE_MOVE_PMD 237 select HAVE_MOVE_PUD 238 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 239 select HAVE_NMI 240 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 241 select HAVE_OBJTOOL if X86_64 242 select HAVE_OPTPROBES 243 select HAVE_PCSPKR_PLATFORM 244 select HAVE_PERF_EVENTS 245 select HAVE_PERF_EVENTS_NMI 246 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 247 select HAVE_PCI 248 select HAVE_PERF_REGS 249 select HAVE_PERF_USER_STACK_DUMP 250 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 251 select MMU_GATHER_MERGE_VMAS 252 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 253 select HAVE_REGS_AND_STACK_ACCESS_API 254 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 255 select HAVE_FUNCTION_ARG_ACCESS_API 256 select HAVE_SETUP_PER_CPU_AREA 257 select HAVE_SOFTIRQ_ON_OWN_STACK 258 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 259 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 260 select HAVE_STATIC_CALL 261 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 262 select HAVE_PREEMPT_DYNAMIC_CALL 263 select HAVE_RSEQ 264 select HAVE_SYSCALL_TRACEPOINTS 265 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 266 select HAVE_UNSTABLE_SCHED_CLOCK 267 select HAVE_USER_RETURN_NOTIFIER 268 select HAVE_GENERIC_VDSO 269 select HOTPLUG_SMT if SMP 270 select IRQ_FORCED_THREADING 271 select NEED_PER_CPU_EMBED_FIRST_CHUNK 272 select NEED_PER_CPU_PAGE_FIRST_CHUNK 273 select NEED_SG_DMA_LENGTH 274 select PCI_DOMAINS if PCI 275 select PCI_LOCKLESS_CONFIG if PCI 276 select PERF_EVENTS 277 select RTC_LIB 278 select RTC_MC146818_LIB 279 select SPARSE_IRQ 280 select SRCU 281 select SYSCTL_EXCEPTION_TRACE 282 select THREAD_INFO_IN_TASK 283 select TRACE_IRQFLAGS_SUPPORT 284 select TRACE_IRQFLAGS_NMI_SUPPORT 285 select USER_STACKTRACE_SUPPORT 286 select HAVE_ARCH_KCSAN if X86_64 287 select X86_FEATURE_NAMES if PROC_FS 288 select PROC_PID_ARCH_STATUS if PROC_FS 289 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 290 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 291 292config INSTRUCTION_DECODER 293 def_bool y 294 depends on KPROBES || PERF_EVENTS || UPROBES 295 296config OUTPUT_FORMAT 297 string 298 default "elf32-i386" if X86_32 299 default "elf64-x86-64" if X86_64 300 301config LOCKDEP_SUPPORT 302 def_bool y 303 304config STACKTRACE_SUPPORT 305 def_bool y 306 307config MMU 308 def_bool y 309 310config ARCH_MMAP_RND_BITS_MIN 311 default 28 if 64BIT 312 default 8 313 314config ARCH_MMAP_RND_BITS_MAX 315 default 32 if 64BIT 316 default 16 317 318config ARCH_MMAP_RND_COMPAT_BITS_MIN 319 default 8 320 321config ARCH_MMAP_RND_COMPAT_BITS_MAX 322 default 16 323 324config SBUS 325 bool 326 327config GENERIC_ISA_DMA 328 def_bool y 329 depends on ISA_DMA_API 330 331config GENERIC_CSUM 332 bool 333 default y if KMSAN || KASAN 334 335config GENERIC_BUG 336 def_bool y 337 depends on BUG 338 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 339 340config GENERIC_BUG_RELATIVE_POINTERS 341 bool 342 343config ARCH_MAY_HAVE_PC_FDC 344 def_bool y 345 depends on ISA_DMA_API 346 347config GENERIC_CALIBRATE_DELAY 348 def_bool y 349 350config ARCH_HAS_CPU_RELAX 351 def_bool y 352 353config ARCH_HIBERNATION_POSSIBLE 354 def_bool y 355 356config ARCH_NR_GPIO 357 int 358 default 1024 if X86_64 359 default 512 360 361config ARCH_SUSPEND_POSSIBLE 362 def_bool y 363 364config AUDIT_ARCH 365 def_bool y if X86_64 366 367config KASAN_SHADOW_OFFSET 368 hex 369 depends on KASAN 370 default 0xdffffc0000000000 371 372config HAVE_INTEL_TXT 373 def_bool y 374 depends on INTEL_IOMMU && ACPI 375 376config X86_32_SMP 377 def_bool y 378 depends on X86_32 && SMP 379 380config X86_64_SMP 381 def_bool y 382 depends on X86_64 && SMP 383 384config ARCH_SUPPORTS_UPROBES 385 def_bool y 386 387config FIX_EARLYCON_MEM 388 def_bool y 389 390config DYNAMIC_PHYSICAL_MASK 391 bool 392 393config PGTABLE_LEVELS 394 int 395 default 5 if X86_5LEVEL 396 default 4 if X86_64 397 default 3 if X86_PAE 398 default 2 399 400config CC_HAS_SANE_STACKPROTECTOR 401 bool 402 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 403 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 404 help 405 We have to make sure stack protector is unconditionally disabled if 406 the compiler produces broken code or if it does not let us control 407 the segment on 32-bit kernels. 408 409menu "Processor type and features" 410 411config SMP 412 bool "Symmetric multi-processing support" 413 help 414 This enables support for systems with more than one CPU. If you have 415 a system with only one CPU, say N. If you have a system with more 416 than one CPU, say Y. 417 418 If you say N here, the kernel will run on uni- and multiprocessor 419 machines, but will use only one CPU of a multiprocessor machine. If 420 you say Y here, the kernel will run on many, but not all, 421 uniprocessor machines. On a uniprocessor machine, the kernel 422 will run faster if you say N here. 423 424 Note that if you say Y here and choose architecture "586" or 425 "Pentium" under "Processor family", the kernel will not work on 486 426 architectures. Similarly, multiprocessor kernels for the "PPro" 427 architecture may not work on all Pentium based boards. 428 429 People using multiprocessor machines who say Y here should also say 430 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 431 Management" code will be disabled if you say Y here. 432 433 See also <file:Documentation/x86/i386/IO-APIC.rst>, 434 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 435 <http://www.tldp.org/docs.html#howto>. 436 437 If you don't know what to do here, say N. 438 439config X86_FEATURE_NAMES 440 bool "Processor feature human-readable names" if EMBEDDED 441 default y 442 help 443 This option compiles in a table of x86 feature bits and corresponding 444 names. This is required to support /proc/cpuinfo and a few kernel 445 messages. You can disable this to save space, at the expense of 446 making those few kernel messages show numeric feature bits instead. 447 448 If in doubt, say Y. 449 450config X86_X2APIC 451 bool "Support x2apic" 452 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 453 help 454 This enables x2apic support on CPUs that have this feature. 455 456 This allows 32-bit apic IDs (so it can support very large systems), 457 and accesses the local apic via MSRs not via mmio. 458 459 If you don't know what to do here, say N. 460 461config X86_MPPARSE 462 bool "Enable MPS table" if ACPI 463 default y 464 depends on X86_LOCAL_APIC 465 help 466 For old smp systems that do not have proper acpi support. Newer systems 467 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 468 469config GOLDFISH 470 def_bool y 471 depends on X86_GOLDFISH 472 473config X86_CPU_RESCTRL 474 bool "x86 CPU resource control support" 475 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 476 select KERNFS 477 select PROC_CPU_RESCTRL if PROC_FS 478 help 479 Enable x86 CPU resource control support. 480 481 Provide support for the allocation and monitoring of system resources 482 usage by the CPU. 483 484 Intel calls this Intel Resource Director Technology 485 (Intel(R) RDT). More information about RDT can be found in the 486 Intel x86 Architecture Software Developer Manual. 487 488 AMD calls this AMD Platform Quality of Service (AMD QoS). 489 More information about AMD QoS can be found in the AMD64 Technology 490 Platform Quality of Service Extensions manual. 491 492 Say N if unsure. 493 494if X86_32 495config X86_BIGSMP 496 bool "Support for big SMP systems with more than 8 CPUs" 497 depends on SMP 498 help 499 This option is needed for the systems that have more than 8 CPUs. 500 501config X86_EXTENDED_PLATFORM 502 bool "Support for extended (non-PC) x86 platforms" 503 default y 504 help 505 If you disable this option then the kernel will only support 506 standard PC platforms. (which covers the vast majority of 507 systems out there.) 508 509 If you enable this option then you'll be able to select support 510 for the following (non-PC) 32 bit x86 platforms: 511 Goldfish (Android emulator) 512 AMD Elan 513 RDC R-321x SoC 514 SGI 320/540 (Visual Workstation) 515 STA2X11-based (e.g. Northville) 516 Moorestown MID devices 517 518 If you have one of these systems, or if you want to build a 519 generic distribution kernel, say Y here - otherwise say N. 520endif # X86_32 521 522if X86_64 523config X86_EXTENDED_PLATFORM 524 bool "Support for extended (non-PC) x86 platforms" 525 default y 526 help 527 If you disable this option then the kernel will only support 528 standard PC platforms. (which covers the vast majority of 529 systems out there.) 530 531 If you enable this option then you'll be able to select support 532 for the following (non-PC) 64 bit x86 platforms: 533 Numascale NumaChip 534 ScaleMP vSMP 535 SGI Ultraviolet 536 537 If you have one of these systems, or if you want to build a 538 generic distribution kernel, say Y here - otherwise say N. 539endif # X86_64 540# This is an alphabetically sorted list of 64 bit extended platforms 541# Please maintain the alphabetic order if and when there are additions 542config X86_NUMACHIP 543 bool "Numascale NumaChip" 544 depends on X86_64 545 depends on X86_EXTENDED_PLATFORM 546 depends on NUMA 547 depends on SMP 548 depends on X86_X2APIC 549 depends on PCI_MMCONFIG 550 help 551 Adds support for Numascale NumaChip large-SMP systems. Needed to 552 enable more than ~168 cores. 553 If you don't have one of these, you should say N here. 554 555config X86_VSMP 556 bool "ScaleMP vSMP" 557 select HYPERVISOR_GUEST 558 select PARAVIRT 559 depends on X86_64 && PCI 560 depends on X86_EXTENDED_PLATFORM 561 depends on SMP 562 help 563 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 564 supposed to run on these EM64T-based machines. Only choose this option 565 if you have one of these machines. 566 567config X86_UV 568 bool "SGI Ultraviolet" 569 depends on X86_64 570 depends on X86_EXTENDED_PLATFORM 571 depends on NUMA 572 depends on EFI 573 depends on KEXEC_CORE 574 depends on X86_X2APIC 575 depends on PCI 576 help 577 This option is needed in order to support SGI Ultraviolet systems. 578 If you don't have one of these, you should say N here. 579 580# Following is an alphabetically sorted list of 32 bit extended platforms 581# Please maintain the alphabetic order if and when there are additions 582 583config X86_GOLDFISH 584 bool "Goldfish (Virtual Platform)" 585 depends on X86_EXTENDED_PLATFORM 586 help 587 Enable support for the Goldfish virtual platform used primarily 588 for Android development. Unless you are building for the Android 589 Goldfish emulator say N here. 590 591config X86_INTEL_CE 592 bool "CE4100 TV platform" 593 depends on PCI 594 depends on PCI_GODIRECT 595 depends on X86_IO_APIC 596 depends on X86_32 597 depends on X86_EXTENDED_PLATFORM 598 select X86_REBOOTFIXUPS 599 select OF 600 select OF_EARLY_FLATTREE 601 help 602 Select for the Intel CE media processor (CE4100) SOC. 603 This option compiles in support for the CE4100 SOC for settop 604 boxes and media devices. 605 606config X86_INTEL_MID 607 bool "Intel MID platform support" 608 depends on X86_EXTENDED_PLATFORM 609 depends on X86_PLATFORM_DEVICES 610 depends on PCI 611 depends on X86_64 || (PCI_GOANY && X86_32) 612 depends on X86_IO_APIC 613 select I2C 614 select DW_APB_TIMER 615 select INTEL_SCU_PCI 616 help 617 Select to build a kernel capable of supporting Intel MID (Mobile 618 Internet Device) platform systems which do not have the PCI legacy 619 interfaces. If you are building for a PC class system say N here. 620 621 Intel MID platforms are based on an Intel processor and chipset which 622 consume less power than most of the x86 derivatives. 623 624config X86_INTEL_QUARK 625 bool "Intel Quark platform support" 626 depends on X86_32 627 depends on X86_EXTENDED_PLATFORM 628 depends on X86_PLATFORM_DEVICES 629 depends on X86_TSC 630 depends on PCI 631 depends on PCI_GOANY 632 depends on X86_IO_APIC 633 select IOSF_MBI 634 select INTEL_IMR 635 select COMMON_CLK 636 help 637 Select to include support for Quark X1000 SoC. 638 Say Y here if you have a Quark based system such as the Arduino 639 compatible Intel Galileo. 640 641config X86_INTEL_LPSS 642 bool "Intel Low Power Subsystem Support" 643 depends on X86 && ACPI && PCI 644 select COMMON_CLK 645 select PINCTRL 646 select IOSF_MBI 647 help 648 Select to build support for Intel Low Power Subsystem such as 649 found on Intel Lynxpoint PCH. Selecting this option enables 650 things like clock tree (common clock framework) and pincontrol 651 which are needed by the LPSS peripheral drivers. 652 653config X86_AMD_PLATFORM_DEVICE 654 bool "AMD ACPI2Platform devices support" 655 depends on ACPI 656 select COMMON_CLK 657 select PINCTRL 658 help 659 Select to interpret AMD specific ACPI device to platform device 660 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 661 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 662 implemented under PINCTRL subsystem. 663 664config IOSF_MBI 665 tristate "Intel SoC IOSF Sideband support for SoC platforms" 666 depends on PCI 667 help 668 This option enables sideband register access support for Intel SoC 669 platforms. On these platforms the IOSF sideband is used in lieu of 670 MSR's for some register accesses, mostly but not limited to thermal 671 and power. Drivers may query the availability of this device to 672 determine if they need the sideband in order to work on these 673 platforms. The sideband is available on the following SoC products. 674 This list is not meant to be exclusive. 675 - BayTrail 676 - Braswell 677 - Quark 678 679 You should say Y if you are running a kernel on one of these SoC's. 680 681config IOSF_MBI_DEBUG 682 bool "Enable IOSF sideband access through debugfs" 683 depends on IOSF_MBI && DEBUG_FS 684 help 685 Select this option to expose the IOSF sideband access registers (MCR, 686 MDR, MCRX) through debugfs to write and read register information from 687 different units on the SoC. This is most useful for obtaining device 688 state information for debug and analysis. As this is a general access 689 mechanism, users of this option would have specific knowledge of the 690 device they want to access. 691 692 If you don't require the option or are in doubt, say N. 693 694config X86_RDC321X 695 bool "RDC R-321x SoC" 696 depends on X86_32 697 depends on X86_EXTENDED_PLATFORM 698 select M486 699 select X86_REBOOTFIXUPS 700 help 701 This option is needed for RDC R-321x system-on-chip, also known 702 as R-8610-(G). 703 If you don't have one of these chips, you should say N here. 704 705config X86_32_NON_STANDARD 706 bool "Support non-standard 32-bit SMP architectures" 707 depends on X86_32 && SMP 708 depends on X86_EXTENDED_PLATFORM 709 help 710 This option compiles in the bigsmp and STA2X11 default 711 subarchitectures. It is intended for a generic binary 712 kernel. If you select them all, kernel will probe it one by 713 one and will fallback to default. 714 715# Alphabetically sorted list of Non standard 32 bit platforms 716 717config X86_SUPPORTS_MEMORY_FAILURE 718 def_bool y 719 # MCE code calls memory_failure(): 720 depends on X86_MCE 721 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 722 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 723 depends on X86_64 || !SPARSEMEM 724 select ARCH_SUPPORTS_MEMORY_FAILURE 725 726config STA2X11 727 bool "STA2X11 Companion Chip Support" 728 depends on X86_32_NON_STANDARD && PCI 729 select SWIOTLB 730 select MFD_STA2X11 731 select GPIOLIB 732 help 733 This adds support for boards based on the STA2X11 IO-Hub, 734 a.k.a. "ConneXt". The chip is used in place of the standard 735 PC chipset, so all "standard" peripherals are missing. If this 736 option is selected the kernel will still be able to boot on 737 standard PC machines. 738 739config X86_32_IRIS 740 tristate "Eurobraille/Iris poweroff module" 741 depends on X86_32 742 help 743 The Iris machines from EuroBraille do not have APM or ACPI support 744 to shut themselves down properly. A special I/O sequence is 745 needed to do so, which is what this module does at 746 kernel shutdown. 747 748 This is only for Iris machines from EuroBraille. 749 750 If unused, say N. 751 752config SCHED_OMIT_FRAME_POINTER 753 def_bool y 754 prompt "Single-depth WCHAN output" 755 depends on X86 756 help 757 Calculate simpler /proc/<PID>/wchan values. If this option 758 is disabled then wchan values will recurse back to the 759 caller function. This provides more accurate wchan values, 760 at the expense of slightly more scheduling overhead. 761 762 If in doubt, say "Y". 763 764menuconfig HYPERVISOR_GUEST 765 bool "Linux guest support" 766 help 767 Say Y here to enable options for running Linux under various hyper- 768 visors. This option enables basic hypervisor detection and platform 769 setup. 770 771 If you say N, all options in this submenu will be skipped and 772 disabled, and Linux guest support won't be built in. 773 774if HYPERVISOR_GUEST 775 776config PARAVIRT 777 bool "Enable paravirtualization code" 778 depends on HAVE_STATIC_CALL 779 help 780 This changes the kernel so it can modify itself when it is run 781 under a hypervisor, potentially improving performance significantly 782 over full virtualization. However, when run without a hypervisor 783 the kernel is theoretically slower and slightly larger. 784 785config PARAVIRT_XXL 786 bool 787 788config PARAVIRT_DEBUG 789 bool "paravirt-ops debugging" 790 depends on PARAVIRT && DEBUG_KERNEL 791 help 792 Enable to debug paravirt_ops internals. Specifically, BUG if 793 a paravirt_op is missing when it is called. 794 795config PARAVIRT_SPINLOCKS 796 bool "Paravirtualization layer for spinlocks" 797 depends on PARAVIRT && SMP 798 help 799 Paravirtualized spinlocks allow a pvops backend to replace the 800 spinlock implementation with something virtualization-friendly 801 (for example, block the virtual CPU rather than spinning). 802 803 It has a minimal impact on native kernels and gives a nice performance 804 benefit on paravirtualized KVM / Xen kernels. 805 806 If you are unsure how to answer this question, answer Y. 807 808config X86_HV_CALLBACK_VECTOR 809 def_bool n 810 811source "arch/x86/xen/Kconfig" 812 813config KVM_GUEST 814 bool "KVM Guest support (including kvmclock)" 815 depends on PARAVIRT 816 select PARAVIRT_CLOCK 817 select ARCH_CPUIDLE_HALTPOLL 818 select X86_HV_CALLBACK_VECTOR 819 default y 820 help 821 This option enables various optimizations for running under the KVM 822 hypervisor. It includes a paravirtualized clock, so that instead 823 of relying on a PIT (or probably other) emulation by the 824 underlying device model, the host provides the guest with 825 timing infrastructure such as time of day, and system time 826 827config ARCH_CPUIDLE_HALTPOLL 828 def_bool n 829 prompt "Disable host haltpoll when loading haltpoll driver" 830 help 831 If virtualized under KVM, disable host haltpoll. 832 833config PVH 834 bool "Support for running PVH guests" 835 help 836 This option enables the PVH entry point for guest virtual machines 837 as specified in the x86/HVM direct boot ABI. 838 839config PARAVIRT_TIME_ACCOUNTING 840 bool "Paravirtual steal time accounting" 841 depends on PARAVIRT 842 help 843 Select this option to enable fine granularity task steal time 844 accounting. Time spent executing other tasks in parallel with 845 the current vCPU is discounted from the vCPU power. To account for 846 that, there can be a small performance impact. 847 848 If in doubt, say N here. 849 850config PARAVIRT_CLOCK 851 bool 852 853config JAILHOUSE_GUEST 854 bool "Jailhouse non-root cell support" 855 depends on X86_64 && PCI 856 select X86_PM_TIMER 857 help 858 This option allows to run Linux as guest in a Jailhouse non-root 859 cell. You can leave this option disabled if you only want to start 860 Jailhouse and run Linux afterwards in the root cell. 861 862config ACRN_GUEST 863 bool "ACRN Guest support" 864 depends on X86_64 865 select X86_HV_CALLBACK_VECTOR 866 help 867 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 868 a flexible, lightweight reference open-source hypervisor, built with 869 real-time and safety-criticality in mind. It is built for embedded 870 IOT with small footprint and real-time features. More details can be 871 found in https://projectacrn.org/. 872 873config INTEL_TDX_GUEST 874 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 875 depends on X86_64 && CPU_SUP_INTEL 876 depends on X86_X2APIC 877 select ARCH_HAS_CC_PLATFORM 878 select X86_MEM_ENCRYPT 879 select X86_MCE 880 help 881 Support running as a guest under Intel TDX. Without this support, 882 the guest kernel can not boot or run under TDX. 883 TDX includes memory encryption and integrity capabilities 884 which protect the confidentiality and integrity of guest 885 memory contents and CPU state. TDX guests are protected from 886 some attacks from the VMM. 887 888endif # HYPERVISOR_GUEST 889 890source "arch/x86/Kconfig.cpu" 891 892config HPET_TIMER 893 def_bool X86_64 894 prompt "HPET Timer Support" if X86_32 895 help 896 Use the IA-PC HPET (High Precision Event Timer) to manage 897 time in preference to the PIT and RTC, if a HPET is 898 present. 899 HPET is the next generation timer replacing legacy 8254s. 900 The HPET provides a stable time base on SMP 901 systems, unlike the TSC, but it is more expensive to access, 902 as it is off-chip. The interface used is documented 903 in the HPET spec, revision 1. 904 905 You can safely choose Y here. However, HPET will only be 906 activated if the platform and the BIOS support this feature. 907 Otherwise the 8254 will be used for timing services. 908 909 Choose N to continue using the legacy 8254 timer. 910 911config HPET_EMULATE_RTC 912 def_bool y 913 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 914 915# Mark as expert because too many people got it wrong. 916# The code disables itself when not needed. 917config DMI 918 default y 919 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 920 bool "Enable DMI scanning" if EXPERT 921 help 922 Enabled scanning of DMI to identify machine quirks. Say Y 923 here unless you have verified that your setup is not 924 affected by entries in the DMI blacklist. Required by PNP 925 BIOS code. 926 927config GART_IOMMU 928 bool "Old AMD GART IOMMU support" 929 select DMA_OPS 930 select IOMMU_HELPER 931 select SWIOTLB 932 depends on X86_64 && PCI && AMD_NB 933 help 934 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 935 GART based hardware IOMMUs. 936 937 The GART supports full DMA access for devices with 32-bit access 938 limitations, on systems with more than 3 GB. This is usually needed 939 for USB, sound, many IDE/SATA chipsets and some other devices. 940 941 Newer systems typically have a modern AMD IOMMU, supported via 942 the CONFIG_AMD_IOMMU=y config option. 943 944 In normal configurations this driver is only active when needed: 945 there's more than 3 GB of memory and the system contains a 946 32-bit limited device. 947 948 If unsure, say Y. 949 950config BOOT_VESA_SUPPORT 951 bool 952 help 953 If true, at least one selected framebuffer driver can take advantage 954 of VESA video modes set at an early boot stage via the vga= parameter. 955 956config MAXSMP 957 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 958 depends on X86_64 && SMP && DEBUG_KERNEL 959 select CPUMASK_OFFSTACK 960 help 961 Enable maximum number of CPUS and NUMA Nodes for this architecture. 962 If unsure, say N. 963 964# 965# The maximum number of CPUs supported: 966# 967# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 968# and which can be configured interactively in the 969# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 970# 971# The ranges are different on 32-bit and 64-bit kernels, depending on 972# hardware capabilities and scalability features of the kernel. 973# 974# ( If MAXSMP is enabled we just use the highest possible value and disable 975# interactive configuration. ) 976# 977 978config NR_CPUS_RANGE_BEGIN 979 int 980 default NR_CPUS_RANGE_END if MAXSMP 981 default 1 if !SMP 982 default 2 983 984config NR_CPUS_RANGE_END 985 int 986 depends on X86_32 987 default 64 if SMP && X86_BIGSMP 988 default 8 if SMP && !X86_BIGSMP 989 default 1 if !SMP 990 991config NR_CPUS_RANGE_END 992 int 993 depends on X86_64 994 default 8192 if SMP && CPUMASK_OFFSTACK 995 default 512 if SMP && !CPUMASK_OFFSTACK 996 default 1 if !SMP 997 998config NR_CPUS_DEFAULT 999 int 1000 depends on X86_32 1001 default 32 if X86_BIGSMP 1002 default 8 if SMP 1003 default 1 if !SMP 1004 1005config NR_CPUS_DEFAULT 1006 int 1007 depends on X86_64 1008 default 8192 if MAXSMP 1009 default 64 if SMP 1010 default 1 if !SMP 1011 1012config NR_CPUS 1013 int "Maximum number of CPUs" if SMP && !MAXSMP 1014 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1015 default NR_CPUS_DEFAULT 1016 help 1017 This allows you to specify the maximum number of CPUs which this 1018 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1019 supported value is 8192, otherwise the maximum value is 512. The 1020 minimum value which makes sense is 2. 1021 1022 This is purely to save memory: each supported CPU adds about 8KB 1023 to the kernel image. 1024 1025config SCHED_CLUSTER 1026 bool "Cluster scheduler support" 1027 depends on SMP 1028 default y 1029 help 1030 Cluster scheduler support improves the CPU scheduler's decision 1031 making when dealing with machines that have clusters of CPUs. 1032 Cluster usually means a couple of CPUs which are placed closely 1033 by sharing mid-level caches, last-level cache tags or internal 1034 busses. 1035 1036config SCHED_SMT 1037 def_bool y if SMP 1038 1039config SCHED_MC 1040 def_bool y 1041 prompt "Multi-core scheduler support" 1042 depends on SMP 1043 help 1044 Multi-core scheduler support improves the CPU scheduler's decision 1045 making when dealing with multi-core CPU chips at a cost of slightly 1046 increased overhead in some places. If unsure say N here. 1047 1048config SCHED_MC_PRIO 1049 bool "CPU core priorities scheduler support" 1050 depends on SCHED_MC && CPU_SUP_INTEL 1051 select X86_INTEL_PSTATE 1052 select CPU_FREQ 1053 default y 1054 help 1055 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1056 core ordering determined at manufacturing time, which allows 1057 certain cores to reach higher turbo frequencies (when running 1058 single threaded workloads) than others. 1059 1060 Enabling this kernel feature teaches the scheduler about 1061 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1062 scheduler's CPU selection logic accordingly, so that higher 1063 overall system performance can be achieved. 1064 1065 This feature will have no effect on CPUs without this feature. 1066 1067 If unsure say Y here. 1068 1069config UP_LATE_INIT 1070 def_bool y 1071 depends on !SMP && X86_LOCAL_APIC 1072 1073config X86_UP_APIC 1074 bool "Local APIC support on uniprocessors" if !PCI_MSI 1075 default PCI_MSI 1076 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1077 help 1078 A local APIC (Advanced Programmable Interrupt Controller) is an 1079 integrated interrupt controller in the CPU. If you have a single-CPU 1080 system which has a processor with a local APIC, you can say Y here to 1081 enable and use it. If you say Y here even though your machine doesn't 1082 have a local APIC, then the kernel will still run with no slowdown at 1083 all. The local APIC supports CPU-generated self-interrupts (timer, 1084 performance counters), and the NMI watchdog which detects hard 1085 lockups. 1086 1087config X86_UP_IOAPIC 1088 bool "IO-APIC support on uniprocessors" 1089 depends on X86_UP_APIC 1090 help 1091 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1092 SMP-capable replacement for PC-style interrupt controllers. Most 1093 SMP systems and many recent uniprocessor systems have one. 1094 1095 If you have a single-CPU system with an IO-APIC, you can say Y here 1096 to use it. If you say Y here even though your machine doesn't have 1097 an IO-APIC, then the kernel will still run with no slowdown at all. 1098 1099config X86_LOCAL_APIC 1100 def_bool y 1101 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1102 select IRQ_DOMAIN_HIERARCHY 1103 select PCI_MSI_IRQ_DOMAIN if PCI_MSI 1104 1105config X86_IO_APIC 1106 def_bool y 1107 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1108 1109config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1110 bool "Reroute for broken boot IRQs" 1111 depends on X86_IO_APIC 1112 help 1113 This option enables a workaround that fixes a source of 1114 spurious interrupts. This is recommended when threaded 1115 interrupt handling is used on systems where the generation of 1116 superfluous "boot interrupts" cannot be disabled. 1117 1118 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1119 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1120 kernel does during interrupt handling). On chipsets where this 1121 boot IRQ generation cannot be disabled, this workaround keeps 1122 the original IRQ line masked so that only the equivalent "boot 1123 IRQ" is delivered to the CPUs. The workaround also tells the 1124 kernel to set up the IRQ handler on the boot IRQ line. In this 1125 way only one interrupt is delivered to the kernel. Otherwise 1126 the spurious second interrupt may cause the kernel to bring 1127 down (vital) interrupt lines. 1128 1129 Only affects "broken" chipsets. Interrupt sharing may be 1130 increased on these systems. 1131 1132config X86_MCE 1133 bool "Machine Check / overheating reporting" 1134 select GENERIC_ALLOCATOR 1135 default y 1136 help 1137 Machine Check support allows the processor to notify the 1138 kernel if it detects a problem (e.g. overheating, data corruption). 1139 The action the kernel takes depends on the severity of the problem, 1140 ranging from warning messages to halting the machine. 1141 1142config X86_MCELOG_LEGACY 1143 bool "Support for deprecated /dev/mcelog character device" 1144 depends on X86_MCE 1145 help 1146 Enable support for /dev/mcelog which is needed by the old mcelog 1147 userspace logging daemon. Consider switching to the new generation 1148 rasdaemon solution. 1149 1150config X86_MCE_INTEL 1151 def_bool y 1152 prompt "Intel MCE features" 1153 depends on X86_MCE && X86_LOCAL_APIC 1154 help 1155 Additional support for intel specific MCE features such as 1156 the thermal monitor. 1157 1158config X86_MCE_AMD 1159 def_bool y 1160 prompt "AMD MCE features" 1161 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1162 help 1163 Additional support for AMD specific MCE features such as 1164 the DRAM Error Threshold. 1165 1166config X86_ANCIENT_MCE 1167 bool "Support for old Pentium 5 / WinChip machine checks" 1168 depends on X86_32 && X86_MCE 1169 help 1170 Include support for machine check handling on old Pentium 5 or WinChip 1171 systems. These typically need to be enabled explicitly on the command 1172 line. 1173 1174config X86_MCE_THRESHOLD 1175 depends on X86_MCE_AMD || X86_MCE_INTEL 1176 def_bool y 1177 1178config X86_MCE_INJECT 1179 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1180 tristate "Machine check injector support" 1181 help 1182 Provide support for injecting machine checks for testing purposes. 1183 If you don't know what a machine check is and you don't do kernel 1184 QA it is safe to say n. 1185 1186source "arch/x86/events/Kconfig" 1187 1188config X86_LEGACY_VM86 1189 bool "Legacy VM86 support" 1190 depends on X86_32 1191 help 1192 This option allows user programs to put the CPU into V8086 1193 mode, which is an 80286-era approximation of 16-bit real mode. 1194 1195 Some very old versions of X and/or vbetool require this option 1196 for user mode setting. Similarly, DOSEMU will use it if 1197 available to accelerate real mode DOS programs. However, any 1198 recent version of DOSEMU, X, or vbetool should be fully 1199 functional even without kernel VM86 support, as they will all 1200 fall back to software emulation. Nevertheless, if you are using 1201 a 16-bit DOS program where 16-bit performance matters, vm86 1202 mode might be faster than emulation and you might want to 1203 enable this option. 1204 1205 Note that any app that works on a 64-bit kernel is unlikely to 1206 need this option, as 64-bit kernels don't, and can't, support 1207 V8086 mode. This option is also unrelated to 16-bit protected 1208 mode and is not needed to run most 16-bit programs under Wine. 1209 1210 Enabling this option increases the complexity of the kernel 1211 and slows down exception handling a tiny bit. 1212 1213 If unsure, say N here. 1214 1215config VM86 1216 bool 1217 default X86_LEGACY_VM86 1218 1219config X86_16BIT 1220 bool "Enable support for 16-bit segments" if EXPERT 1221 default y 1222 depends on MODIFY_LDT_SYSCALL 1223 help 1224 This option is required by programs like Wine to run 16-bit 1225 protected mode legacy code on x86 processors. Disabling 1226 this option saves about 300 bytes on i386, or around 6K text 1227 plus 16K runtime memory on x86-64, 1228 1229config X86_ESPFIX32 1230 def_bool y 1231 depends on X86_16BIT && X86_32 1232 1233config X86_ESPFIX64 1234 def_bool y 1235 depends on X86_16BIT && X86_64 1236 1237config X86_VSYSCALL_EMULATION 1238 bool "Enable vsyscall emulation" if EXPERT 1239 default y 1240 depends on X86_64 1241 help 1242 This enables emulation of the legacy vsyscall page. Disabling 1243 it is roughly equivalent to booting with vsyscall=none, except 1244 that it will also disable the helpful warning if a program 1245 tries to use a vsyscall. With this option set to N, offending 1246 programs will just segfault, citing addresses of the form 1247 0xffffffffff600?00. 1248 1249 This option is required by many programs built before 2013, and 1250 care should be used even with newer programs if set to N. 1251 1252 Disabling this option saves about 7K of kernel size and 1253 possibly 4K of additional runtime pagetable memory. 1254 1255config X86_IOPL_IOPERM 1256 bool "IOPERM and IOPL Emulation" 1257 default y 1258 help 1259 This enables the ioperm() and iopl() syscalls which are necessary 1260 for legacy applications. 1261 1262 Legacy IOPL support is an overbroad mechanism which allows user 1263 space aside of accessing all 65536 I/O ports also to disable 1264 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1265 capabilities and permission from potentially active security 1266 modules. 1267 1268 The emulation restricts the functionality of the syscall to 1269 only allowing the full range I/O port access, but prevents the 1270 ability to disable interrupts from user space which would be 1271 granted if the hardware IOPL mechanism would be used. 1272 1273config TOSHIBA 1274 tristate "Toshiba Laptop support" 1275 depends on X86_32 1276 help 1277 This adds a driver to safely access the System Management Mode of 1278 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1279 not work on models with a Phoenix BIOS. The System Management Mode 1280 is used to set the BIOS and power saving options on Toshiba portables. 1281 1282 For information on utilities to make use of this driver see the 1283 Toshiba Linux utilities web site at: 1284 <http://www.buzzard.org.uk/toshiba/>. 1285 1286 Say Y if you intend to run this kernel on a Toshiba portable. 1287 Say N otherwise. 1288 1289config X86_REBOOTFIXUPS 1290 bool "Enable X86 board specific fixups for reboot" 1291 depends on X86_32 1292 help 1293 This enables chipset and/or board specific fixups to be done 1294 in order to get reboot to work correctly. This is only needed on 1295 some combinations of hardware and BIOS. The symptom, for which 1296 this config is intended, is when reboot ends with a stalled/hung 1297 system. 1298 1299 Currently, the only fixup is for the Geode machines using 1300 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1301 1302 Say Y if you want to enable the fixup. Currently, it's safe to 1303 enable this option even if you don't need it. 1304 Say N otherwise. 1305 1306config MICROCODE 1307 bool "CPU microcode loading support" 1308 default y 1309 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1310 help 1311 If you say Y here, you will be able to update the microcode on 1312 Intel and AMD processors. The Intel support is for the IA32 family, 1313 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1314 AMD support is for families 0x10 and later. You will obviously need 1315 the actual microcode binary data itself which is not shipped with 1316 the Linux kernel. 1317 1318 The preferred method to load microcode from a detached initrd is described 1319 in Documentation/x86/microcode.rst. For that you need to enable 1320 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1321 initrd for microcode blobs. 1322 1323 In addition, you can build the microcode into the kernel. For that you 1324 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1325 config option. 1326 1327config MICROCODE_INTEL 1328 bool "Intel microcode loading support" 1329 depends on CPU_SUP_INTEL && MICROCODE 1330 default MICROCODE 1331 help 1332 This options enables microcode patch loading support for Intel 1333 processors. 1334 1335 For the current Intel microcode data package go to 1336 <https://downloadcenter.intel.com> and search for 1337 'Linux Processor Microcode Data File'. 1338 1339config MICROCODE_AMD 1340 bool "AMD microcode loading support" 1341 depends on CPU_SUP_AMD && MICROCODE 1342 help 1343 If you select this option, microcode patch loading support for AMD 1344 processors will be enabled. 1345 1346config MICROCODE_LATE_LOADING 1347 bool "Late microcode loading (DANGEROUS)" 1348 default n 1349 depends on MICROCODE 1350 help 1351 Loading microcode late, when the system is up and executing instructions 1352 is a tricky business and should be avoided if possible. Just the sequence 1353 of synchronizing all cores and SMT threads is one fragile dance which does 1354 not guarantee that cores might not softlock after the loading. Therefore, 1355 use this at your own risk. Late loading taints the kernel too. 1356 1357config X86_MSR 1358 tristate "/dev/cpu/*/msr - Model-specific register support" 1359 help 1360 This device gives privileged processes access to the x86 1361 Model-Specific Registers (MSRs). It is a character device with 1362 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1363 MSR accesses are directed to a specific CPU on multi-processor 1364 systems. 1365 1366config X86_CPUID 1367 tristate "/dev/cpu/*/cpuid - CPU information support" 1368 help 1369 This device gives processes access to the x86 CPUID instruction to 1370 be executed on a specific processor. It is a character device 1371 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1372 /dev/cpu/31/cpuid. 1373 1374choice 1375 prompt "High Memory Support" 1376 default HIGHMEM4G 1377 depends on X86_32 1378 1379config NOHIGHMEM 1380 bool "off" 1381 help 1382 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1383 However, the address space of 32-bit x86 processors is only 4 1384 Gigabytes large. That means that, if you have a large amount of 1385 physical memory, not all of it can be "permanently mapped" by the 1386 kernel. The physical memory that's not permanently mapped is called 1387 "high memory". 1388 1389 If you are compiling a kernel which will never run on a machine with 1390 more than 1 Gigabyte total physical RAM, answer "off" here (default 1391 choice and suitable for most users). This will result in a "3GB/1GB" 1392 split: 3GB are mapped so that each process sees a 3GB virtual memory 1393 space and the remaining part of the 4GB virtual memory space is used 1394 by the kernel to permanently map as much physical memory as 1395 possible. 1396 1397 If the machine has between 1 and 4 Gigabytes physical RAM, then 1398 answer "4GB" here. 1399 1400 If more than 4 Gigabytes is used then answer "64GB" here. This 1401 selection turns Intel PAE (Physical Address Extension) mode on. 1402 PAE implements 3-level paging on IA32 processors. PAE is fully 1403 supported by Linux, PAE mode is implemented on all recent Intel 1404 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1405 then the kernel will not boot on CPUs that don't support PAE! 1406 1407 The actual amount of total physical memory will either be 1408 auto detected or can be forced by using a kernel command line option 1409 such as "mem=256M". (Try "man bootparam" or see the documentation of 1410 your boot loader (lilo or loadlin) about how to pass options to the 1411 kernel at boot time.) 1412 1413 If unsure, say "off". 1414 1415config HIGHMEM4G 1416 bool "4GB" 1417 help 1418 Select this if you have a 32-bit processor and between 1 and 4 1419 gigabytes of physical RAM. 1420 1421config HIGHMEM64G 1422 bool "64GB" 1423 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1424 select X86_PAE 1425 help 1426 Select this if you have a 32-bit processor and more than 4 1427 gigabytes of physical RAM. 1428 1429endchoice 1430 1431choice 1432 prompt "Memory split" if EXPERT 1433 default VMSPLIT_3G 1434 depends on X86_32 1435 help 1436 Select the desired split between kernel and user memory. 1437 1438 If the address range available to the kernel is less than the 1439 physical memory installed, the remaining memory will be available 1440 as "high memory". Accessing high memory is a little more costly 1441 than low memory, as it needs to be mapped into the kernel first. 1442 Note that increasing the kernel address space limits the range 1443 available to user programs, making the address space there 1444 tighter. Selecting anything other than the default 3G/1G split 1445 will also likely make your kernel incompatible with binary-only 1446 kernel modules. 1447 1448 If you are not absolutely sure what you are doing, leave this 1449 option alone! 1450 1451 config VMSPLIT_3G 1452 bool "3G/1G user/kernel split" 1453 config VMSPLIT_3G_OPT 1454 depends on !X86_PAE 1455 bool "3G/1G user/kernel split (for full 1G low memory)" 1456 config VMSPLIT_2G 1457 bool "2G/2G user/kernel split" 1458 config VMSPLIT_2G_OPT 1459 depends on !X86_PAE 1460 bool "2G/2G user/kernel split (for full 2G low memory)" 1461 config VMSPLIT_1G 1462 bool "1G/3G user/kernel split" 1463endchoice 1464 1465config PAGE_OFFSET 1466 hex 1467 default 0xB0000000 if VMSPLIT_3G_OPT 1468 default 0x80000000 if VMSPLIT_2G 1469 default 0x78000000 if VMSPLIT_2G_OPT 1470 default 0x40000000 if VMSPLIT_1G 1471 default 0xC0000000 1472 depends on X86_32 1473 1474config HIGHMEM 1475 def_bool y 1476 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1477 1478config X86_PAE 1479 bool "PAE (Physical Address Extension) Support" 1480 depends on X86_32 && !HIGHMEM4G 1481 select PHYS_ADDR_T_64BIT 1482 select SWIOTLB 1483 help 1484 PAE is required for NX support, and furthermore enables 1485 larger swapspace support for non-overcommit purposes. It 1486 has the cost of more pagetable lookup overhead, and also 1487 consumes more pagetable space per process. 1488 1489config X86_5LEVEL 1490 bool "Enable 5-level page tables support" 1491 default y 1492 select DYNAMIC_MEMORY_LAYOUT 1493 select SPARSEMEM_VMEMMAP 1494 depends on X86_64 1495 help 1496 5-level paging enables access to larger address space: 1497 upto 128 PiB of virtual address space and 4 PiB of 1498 physical address space. 1499 1500 It will be supported by future Intel CPUs. 1501 1502 A kernel with the option enabled can be booted on machines that 1503 support 4- or 5-level paging. 1504 1505 See Documentation/x86/x86_64/5level-paging.rst for more 1506 information. 1507 1508 Say N if unsure. 1509 1510config X86_DIRECT_GBPAGES 1511 def_bool y 1512 depends on X86_64 1513 help 1514 Certain kernel features effectively disable kernel 1515 linear 1 GB mappings (even if the CPU otherwise 1516 supports them), so don't confuse the user by printing 1517 that we have them enabled. 1518 1519config X86_CPA_STATISTICS 1520 bool "Enable statistic for Change Page Attribute" 1521 depends on DEBUG_FS 1522 help 1523 Expose statistics about the Change Page Attribute mechanism, which 1524 helps to determine the effectiveness of preserving large and huge 1525 page mappings when mapping protections are changed. 1526 1527config X86_MEM_ENCRYPT 1528 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1529 select DYNAMIC_PHYSICAL_MASK 1530 def_bool n 1531 1532config AMD_MEM_ENCRYPT 1533 bool "AMD Secure Memory Encryption (SME) support" 1534 depends on X86_64 && CPU_SUP_AMD 1535 select DMA_COHERENT_POOL 1536 select ARCH_USE_MEMREMAP_PROT 1537 select INSTRUCTION_DECODER 1538 select ARCH_HAS_CC_PLATFORM 1539 select X86_MEM_ENCRYPT 1540 help 1541 Say yes to enable support for the encryption of system memory. 1542 This requires an AMD processor that supports Secure Memory 1543 Encryption (SME). 1544 1545config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1546 bool "Activate AMD Secure Memory Encryption (SME) by default" 1547 depends on AMD_MEM_ENCRYPT 1548 help 1549 Say yes to have system memory encrypted by default if running on 1550 an AMD processor that supports Secure Memory Encryption (SME). 1551 1552 If set to Y, then the encryption of system memory can be 1553 deactivated with the mem_encrypt=off command line option. 1554 1555 If set to N, then the encryption of system memory can be 1556 activated with the mem_encrypt=on command line option. 1557 1558# Common NUMA Features 1559config NUMA 1560 bool "NUMA Memory Allocation and Scheduler Support" 1561 depends on SMP 1562 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1563 default y if X86_BIGSMP 1564 select USE_PERCPU_NUMA_NODE_ID 1565 help 1566 Enable NUMA (Non-Uniform Memory Access) support. 1567 1568 The kernel will try to allocate memory used by a CPU on the 1569 local memory controller of the CPU and add some more 1570 NUMA awareness to the kernel. 1571 1572 For 64-bit this is recommended if the system is Intel Core i7 1573 (or later), AMD Opteron, or EM64T NUMA. 1574 1575 For 32-bit this is only needed if you boot a 32-bit 1576 kernel on a 64-bit NUMA platform. 1577 1578 Otherwise, you should say N. 1579 1580config AMD_NUMA 1581 def_bool y 1582 prompt "Old style AMD Opteron NUMA detection" 1583 depends on X86_64 && NUMA && PCI 1584 help 1585 Enable AMD NUMA node topology detection. You should say Y here if 1586 you have a multi processor AMD system. This uses an old method to 1587 read the NUMA configuration directly from the builtin Northbridge 1588 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1589 which also takes priority if both are compiled in. 1590 1591config X86_64_ACPI_NUMA 1592 def_bool y 1593 prompt "ACPI NUMA detection" 1594 depends on X86_64 && NUMA && ACPI && PCI 1595 select ACPI_NUMA 1596 help 1597 Enable ACPI SRAT based node topology detection. 1598 1599config NUMA_EMU 1600 bool "NUMA emulation" 1601 depends on NUMA 1602 help 1603 Enable NUMA emulation. A flat machine will be split 1604 into virtual nodes when booted with "numa=fake=N", where N is the 1605 number of nodes. This is only useful for debugging. 1606 1607config NODES_SHIFT 1608 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1609 range 1 10 1610 default "10" if MAXSMP 1611 default "6" if X86_64 1612 default "3" 1613 depends on NUMA 1614 help 1615 Specify the maximum number of NUMA Nodes available on the target 1616 system. Increases memory reserved to accommodate various tables. 1617 1618config ARCH_FLATMEM_ENABLE 1619 def_bool y 1620 depends on X86_32 && !NUMA 1621 1622config ARCH_SPARSEMEM_ENABLE 1623 def_bool y 1624 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1625 select SPARSEMEM_STATIC if X86_32 1626 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1627 1628config ARCH_SPARSEMEM_DEFAULT 1629 def_bool X86_64 || (NUMA && X86_32) 1630 1631config ARCH_SELECT_MEMORY_MODEL 1632 def_bool y 1633 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1634 1635config ARCH_MEMORY_PROBE 1636 bool "Enable sysfs memory/probe interface" 1637 depends on MEMORY_HOTPLUG 1638 help 1639 This option enables a sysfs memory/probe interface for testing. 1640 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1641 If you are unsure how to answer this question, answer N. 1642 1643config ARCH_PROC_KCORE_TEXT 1644 def_bool y 1645 depends on X86_64 && PROC_KCORE 1646 1647config ILLEGAL_POINTER_VALUE 1648 hex 1649 default 0 if X86_32 1650 default 0xdead000000000000 if X86_64 1651 1652config X86_PMEM_LEGACY_DEVICE 1653 bool 1654 1655config X86_PMEM_LEGACY 1656 tristate "Support non-standard NVDIMMs and ADR protected memory" 1657 depends on PHYS_ADDR_T_64BIT 1658 depends on BLK_DEV 1659 select X86_PMEM_LEGACY_DEVICE 1660 select NUMA_KEEP_MEMINFO if NUMA 1661 select LIBNVDIMM 1662 help 1663 Treat memory marked using the non-standard e820 type of 12 as used 1664 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1665 The kernel will offer these regions to the 'pmem' driver so 1666 they can be used for persistent storage. 1667 1668 Say Y if unsure. 1669 1670config HIGHPTE 1671 bool "Allocate 3rd-level pagetables from highmem" 1672 depends on HIGHMEM 1673 help 1674 The VM uses one page table entry for each page of physical memory. 1675 For systems with a lot of RAM, this can be wasteful of precious 1676 low memory. Setting this option will put user-space page table 1677 entries in high memory. 1678 1679config X86_CHECK_BIOS_CORRUPTION 1680 bool "Check for low memory corruption" 1681 help 1682 Periodically check for memory corruption in low memory, which 1683 is suspected to be caused by BIOS. Even when enabled in the 1684 configuration, it is disabled at runtime. Enable it by 1685 setting "memory_corruption_check=1" on the kernel command 1686 line. By default it scans the low 64k of memory every 60 1687 seconds; see the memory_corruption_check_size and 1688 memory_corruption_check_period parameters in 1689 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1690 1691 When enabled with the default parameters, this option has 1692 almost no overhead, as it reserves a relatively small amount 1693 of memory and scans it infrequently. It both detects corruption 1694 and prevents it from affecting the running system. 1695 1696 It is, however, intended as a diagnostic tool; if repeatable 1697 BIOS-originated corruption always affects the same memory, 1698 you can use memmap= to prevent the kernel from using that 1699 memory. 1700 1701config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1702 bool "Set the default setting of memory_corruption_check" 1703 depends on X86_CHECK_BIOS_CORRUPTION 1704 default y 1705 help 1706 Set whether the default state of memory_corruption_check is 1707 on or off. 1708 1709config MATH_EMULATION 1710 bool 1711 depends on MODIFY_LDT_SYSCALL 1712 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1713 help 1714 Linux can emulate a math coprocessor (used for floating point 1715 operations) if you don't have one. 486DX and Pentium processors have 1716 a math coprocessor built in, 486SX and 386 do not, unless you added 1717 a 487DX or 387, respectively. (The messages during boot time can 1718 give you some hints here ["man dmesg"].) Everyone needs either a 1719 coprocessor or this emulation. 1720 1721 If you don't have a math coprocessor, you need to say Y here; if you 1722 say Y here even though you have a coprocessor, the coprocessor will 1723 be used nevertheless. (This behavior can be changed with the kernel 1724 command line option "no387", which comes handy if your coprocessor 1725 is broken. Try "man bootparam" or see the documentation of your boot 1726 loader (lilo or loadlin) about how to pass options to the kernel at 1727 boot time.) This means that it is a good idea to say Y here if you 1728 intend to use this kernel on different machines. 1729 1730 More information about the internals of the Linux math coprocessor 1731 emulation can be found in <file:arch/x86/math-emu/README>. 1732 1733 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1734 kernel, it won't hurt. 1735 1736config MTRR 1737 def_bool y 1738 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1739 help 1740 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1741 the Memory Type Range Registers (MTRRs) may be used to control 1742 processor access to memory ranges. This is most useful if you have 1743 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1744 allows bus write transfers to be combined into a larger transfer 1745 before bursting over the PCI/AGP bus. This can increase performance 1746 of image write operations 2.5 times or more. Saying Y here creates a 1747 /proc/mtrr file which may be used to manipulate your processor's 1748 MTRRs. Typically the X server should use this. 1749 1750 This code has a reasonably generic interface so that similar 1751 control registers on other processors can be easily supported 1752 as well: 1753 1754 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1755 Registers (ARRs) which provide a similar functionality to MTRRs. For 1756 these, the ARRs are used to emulate the MTRRs. 1757 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1758 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1759 write-combining. All of these processors are supported by this code 1760 and it makes sense to say Y here if you have one of them. 1761 1762 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1763 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1764 can lead to all sorts of problems, so it's good to say Y here. 1765 1766 You can safely say Y even if your machine doesn't have MTRRs, you'll 1767 just add about 9 KB to your kernel. 1768 1769 See <file:Documentation/x86/mtrr.rst> for more information. 1770 1771config MTRR_SANITIZER 1772 def_bool y 1773 prompt "MTRR cleanup support" 1774 depends on MTRR 1775 help 1776 Convert MTRR layout from continuous to discrete, so X drivers can 1777 add writeback entries. 1778 1779 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1780 The largest mtrr entry size for a continuous block can be set with 1781 mtrr_chunk_size. 1782 1783 If unsure, say Y. 1784 1785config MTRR_SANITIZER_ENABLE_DEFAULT 1786 int "MTRR cleanup enable value (0-1)" 1787 range 0 1 1788 default "0" 1789 depends on MTRR_SANITIZER 1790 help 1791 Enable mtrr cleanup default value 1792 1793config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1794 int "MTRR cleanup spare reg num (0-7)" 1795 range 0 7 1796 default "1" 1797 depends on MTRR_SANITIZER 1798 help 1799 mtrr cleanup spare entries default, it can be changed via 1800 mtrr_spare_reg_nr=N on the kernel command line. 1801 1802config X86_PAT 1803 def_bool y 1804 prompt "x86 PAT support" if EXPERT 1805 depends on MTRR 1806 help 1807 Use PAT attributes to setup page level cache control. 1808 1809 PATs are the modern equivalents of MTRRs and are much more 1810 flexible than MTRRs. 1811 1812 Say N here if you see bootup problems (boot crash, boot hang, 1813 spontaneous reboots) or a non-working video driver. 1814 1815 If unsure, say Y. 1816 1817config ARCH_USES_PG_UNCACHED 1818 def_bool y 1819 depends on X86_PAT 1820 1821config X86_UMIP 1822 def_bool y 1823 prompt "User Mode Instruction Prevention" if EXPERT 1824 help 1825 User Mode Instruction Prevention (UMIP) is a security feature in 1826 some x86 processors. If enabled, a general protection fault is 1827 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1828 executed in user mode. These instructions unnecessarily expose 1829 information about the hardware state. 1830 1831 The vast majority of applications do not use these instructions. 1832 For the very few that do, software emulation is provided in 1833 specific cases in protected and virtual-8086 modes. Emulated 1834 results are dummy. 1835 1836config CC_HAS_IBT 1837 # GCC >= 9 and binutils >= 2.29 1838 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1839 # Clang/LLVM >= 14 1840 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1841 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1842 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1843 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1844 $(as-instr,endbr64) 1845 1846config X86_KERNEL_IBT 1847 prompt "Indirect Branch Tracking" 1848 bool 1849 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1850 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1851 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1852 select OBJTOOL 1853 help 1854 Build the kernel with support for Indirect Branch Tracking, a 1855 hardware support course-grain forward-edge Control Flow Integrity 1856 protection. It enforces that all indirect calls must land on 1857 an ENDBR instruction, as such, the compiler will instrument the 1858 code with them to make this happen. 1859 1860 In addition to building the kernel with IBT, seal all functions that 1861 are not indirect call targets, avoiding them ever becoming one. 1862 1863 This requires LTO like objtool runs and will slow down the build. It 1864 does significantly reduce the number of ENDBR instructions in the 1865 kernel image. 1866 1867config X86_INTEL_MEMORY_PROTECTION_KEYS 1868 prompt "Memory Protection Keys" 1869 def_bool y 1870 # Note: only available in 64-bit mode 1871 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1872 select ARCH_USES_HIGH_VMA_FLAGS 1873 select ARCH_HAS_PKEYS 1874 help 1875 Memory Protection Keys provides a mechanism for enforcing 1876 page-based protections, but without requiring modification of the 1877 page tables when an application changes protection domains. 1878 1879 For details, see Documentation/core-api/protection-keys.rst 1880 1881 If unsure, say y. 1882 1883choice 1884 prompt "TSX enable mode" 1885 depends on CPU_SUP_INTEL 1886 default X86_INTEL_TSX_MODE_OFF 1887 help 1888 Intel's TSX (Transactional Synchronization Extensions) feature 1889 allows to optimize locking protocols through lock elision which 1890 can lead to a noticeable performance boost. 1891 1892 On the other hand it has been shown that TSX can be exploited 1893 to form side channel attacks (e.g. TAA) and chances are there 1894 will be more of those attacks discovered in the future. 1895 1896 Therefore TSX is not enabled by default (aka tsx=off). An admin 1897 might override this decision by tsx=on the command line parameter. 1898 Even with TSX enabled, the kernel will attempt to enable the best 1899 possible TAA mitigation setting depending on the microcode available 1900 for the particular machine. 1901 1902 This option allows to set the default tsx mode between tsx=on, =off 1903 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1904 details. 1905 1906 Say off if not sure, auto if TSX is in use but it should be used on safe 1907 platforms or on if TSX is in use and the security aspect of tsx is not 1908 relevant. 1909 1910config X86_INTEL_TSX_MODE_OFF 1911 bool "off" 1912 help 1913 TSX is disabled if possible - equals to tsx=off command line parameter. 1914 1915config X86_INTEL_TSX_MODE_ON 1916 bool "on" 1917 help 1918 TSX is always enabled on TSX capable HW - equals the tsx=on command 1919 line parameter. 1920 1921config X86_INTEL_TSX_MODE_AUTO 1922 bool "auto" 1923 help 1924 TSX is enabled on TSX capable HW that is believed to be safe against 1925 side channel attacks- equals the tsx=auto command line parameter. 1926endchoice 1927 1928config X86_SGX 1929 bool "Software Guard eXtensions (SGX)" 1930 depends on X86_64 && CPU_SUP_INTEL 1931 depends on CRYPTO=y 1932 depends on CRYPTO_SHA256=y 1933 select SRCU 1934 select MMU_NOTIFIER 1935 select NUMA_KEEP_MEMINFO if NUMA 1936 select XARRAY_MULTI 1937 help 1938 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1939 that can be used by applications to set aside private regions of code 1940 and data, referred to as enclaves. An enclave's private memory can 1941 only be accessed by code running within the enclave. Accesses from 1942 outside the enclave, including other enclaves, are disallowed by 1943 hardware. 1944 1945 If unsure, say N. 1946 1947config EFI 1948 bool "EFI runtime service support" 1949 depends on ACPI 1950 select UCS2_STRING 1951 select EFI_RUNTIME_WRAPPERS 1952 select ARCH_USE_MEMREMAP_PROT 1953 help 1954 This enables the kernel to use EFI runtime services that are 1955 available (such as the EFI variable services). 1956 1957 This option is only useful on systems that have EFI firmware. 1958 In addition, you should use the latest ELILO loader available 1959 at <http://elilo.sourceforge.net> in order to take advantage 1960 of EFI runtime services. However, even with this option, the 1961 resultant kernel should continue to boot on existing non-EFI 1962 platforms. 1963 1964config EFI_STUB 1965 bool "EFI stub support" 1966 depends on EFI 1967 depends on $(cc-option,-mabi=ms) || X86_32 1968 select RELOCATABLE 1969 help 1970 This kernel feature allows a bzImage to be loaded directly 1971 by EFI firmware without the use of a bootloader. 1972 1973 See Documentation/admin-guide/efi-stub.rst for more information. 1974 1975config EFI_MIXED 1976 bool "EFI mixed-mode support" 1977 depends on EFI_STUB && X86_64 1978 help 1979 Enabling this feature allows a 64-bit kernel to be booted 1980 on a 32-bit firmware, provided that your CPU supports 64-bit 1981 mode. 1982 1983 Note that it is not possible to boot a mixed-mode enabled 1984 kernel via the EFI boot stub - a bootloader that supports 1985 the EFI handover protocol must be used. 1986 1987 If unsure, say N. 1988 1989source "kernel/Kconfig.hz" 1990 1991config KEXEC 1992 bool "kexec system call" 1993 select KEXEC_CORE 1994 help 1995 kexec is a system call that implements the ability to shutdown your 1996 current kernel, and to start another kernel. It is like a reboot 1997 but it is independent of the system firmware. And like a reboot 1998 you can start any kernel with it, not just Linux. 1999 2000 The name comes from the similarity to the exec system call. 2001 2002 It is an ongoing process to be certain the hardware in a machine 2003 is properly shutdown, so do not be surprised if this code does not 2004 initially work for you. As of this writing the exact hardware 2005 interface is strongly in flux, so no good recommendation can be 2006 made. 2007 2008config KEXEC_FILE 2009 bool "kexec file based system call" 2010 select KEXEC_CORE 2011 select HAVE_IMA_KEXEC if IMA 2012 depends on X86_64 2013 depends on CRYPTO=y 2014 depends on CRYPTO_SHA256=y 2015 help 2016 This is new version of kexec system call. This system call is 2017 file based and takes file descriptors as system call argument 2018 for kernel and initramfs as opposed to list of segments as 2019 accepted by previous system call. 2020 2021config ARCH_HAS_KEXEC_PURGATORY 2022 def_bool KEXEC_FILE 2023 2024config KEXEC_SIG 2025 bool "Verify kernel signature during kexec_file_load() syscall" 2026 depends on KEXEC_FILE 2027 help 2028 2029 This option makes the kexec_file_load() syscall check for a valid 2030 signature of the kernel image. The image can still be loaded without 2031 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2032 there's a signature that we can check, then it must be valid. 2033 2034 In addition to this option, you need to enable signature 2035 verification for the corresponding kernel image type being 2036 loaded in order for this to work. 2037 2038config KEXEC_SIG_FORCE 2039 bool "Require a valid signature in kexec_file_load() syscall" 2040 depends on KEXEC_SIG 2041 help 2042 This option makes kernel signature verification mandatory for 2043 the kexec_file_load() syscall. 2044 2045config KEXEC_BZIMAGE_VERIFY_SIG 2046 bool "Enable bzImage signature verification support" 2047 depends on KEXEC_SIG 2048 depends on SIGNED_PE_FILE_VERIFICATION 2049 select SYSTEM_TRUSTED_KEYRING 2050 help 2051 Enable bzImage signature verification support. 2052 2053config CRASH_DUMP 2054 bool "kernel crash dumps" 2055 depends on X86_64 || (X86_32 && HIGHMEM) 2056 help 2057 Generate crash dump after being started by kexec. 2058 This should be normally only set in special crash dump kernels 2059 which are loaded in the main kernel with kexec-tools into 2060 a specially reserved region and then later executed after 2061 a crash by kdump/kexec. The crash dump kernel must be compiled 2062 to a memory address not used by the main kernel or BIOS using 2063 PHYSICAL_START, or it must be built as a relocatable image 2064 (CONFIG_RELOCATABLE=y). 2065 For more details see Documentation/admin-guide/kdump/kdump.rst 2066 2067config KEXEC_JUMP 2068 bool "kexec jump" 2069 depends on KEXEC && HIBERNATION 2070 help 2071 Jump between original kernel and kexeced kernel and invoke 2072 code in physical address mode via KEXEC 2073 2074config PHYSICAL_START 2075 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2076 default "0x1000000" 2077 help 2078 This gives the physical address where the kernel is loaded. 2079 2080 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2081 bzImage will decompress itself to above physical address and 2082 run from there. Otherwise, bzImage will run from the address where 2083 it has been loaded by the boot loader and will ignore above physical 2084 address. 2085 2086 In normal kdump cases one does not have to set/change this option 2087 as now bzImage can be compiled as a completely relocatable image 2088 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2089 address. This option is mainly useful for the folks who don't want 2090 to use a bzImage for capturing the crash dump and want to use a 2091 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2092 to be specifically compiled to run from a specific memory area 2093 (normally a reserved region) and this option comes handy. 2094 2095 So if you are using bzImage for capturing the crash dump, 2096 leave the value here unchanged to 0x1000000 and set 2097 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2098 for capturing the crash dump change this value to start of 2099 the reserved region. In other words, it can be set based on 2100 the "X" value as specified in the "crashkernel=YM@XM" 2101 command line boot parameter passed to the panic-ed 2102 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2103 for more details about crash dumps. 2104 2105 Usage of bzImage for capturing the crash dump is recommended as 2106 one does not have to build two kernels. Same kernel can be used 2107 as production kernel and capture kernel. Above option should have 2108 gone away after relocatable bzImage support is introduced. But it 2109 is present because there are users out there who continue to use 2110 vmlinux for dump capture. This option should go away down the 2111 line. 2112 2113 Don't change this unless you know what you are doing. 2114 2115config RELOCATABLE 2116 bool "Build a relocatable kernel" 2117 default y 2118 help 2119 This builds a kernel image that retains relocation information 2120 so it can be loaded someplace besides the default 1MB. 2121 The relocations tend to make the kernel binary about 10% larger, 2122 but are discarded at runtime. 2123 2124 One use is for the kexec on panic case where the recovery kernel 2125 must live at a different physical address than the primary 2126 kernel. 2127 2128 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2129 it has been loaded at and the compile time physical address 2130 (CONFIG_PHYSICAL_START) is used as the minimum location. 2131 2132config RANDOMIZE_BASE 2133 bool "Randomize the address of the kernel image (KASLR)" 2134 depends on RELOCATABLE 2135 default y 2136 help 2137 In support of Kernel Address Space Layout Randomization (KASLR), 2138 this randomizes the physical address at which the kernel image 2139 is decompressed and the virtual address where the kernel 2140 image is mapped, as a security feature that deters exploit 2141 attempts relying on knowledge of the location of kernel 2142 code internals. 2143 2144 On 64-bit, the kernel physical and virtual addresses are 2145 randomized separately. The physical address will be anywhere 2146 between 16MB and the top of physical memory (up to 64TB). The 2147 virtual address will be randomized from 16MB up to 1GB (9 bits 2148 of entropy). Note that this also reduces the memory space 2149 available to kernel modules from 1.5GB to 1GB. 2150 2151 On 32-bit, the kernel physical and virtual addresses are 2152 randomized together. They will be randomized from 16MB up to 2153 512MB (8 bits of entropy). 2154 2155 Entropy is generated using the RDRAND instruction if it is 2156 supported. If RDTSC is supported, its value is mixed into 2157 the entropy pool as well. If neither RDRAND nor RDTSC are 2158 supported, then entropy is read from the i8254 timer. The 2159 usable entropy is limited by the kernel being built using 2160 2GB addressing, and that PHYSICAL_ALIGN must be at a 2161 minimum of 2MB. As a result, only 10 bits of entropy are 2162 theoretically possible, but the implementations are further 2163 limited due to memory layouts. 2164 2165 If unsure, say Y. 2166 2167# Relocation on x86 needs some additional build support 2168config X86_NEED_RELOCS 2169 def_bool y 2170 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2171 2172config PHYSICAL_ALIGN 2173 hex "Alignment value to which kernel should be aligned" 2174 default "0x200000" 2175 range 0x2000 0x1000000 if X86_32 2176 range 0x200000 0x1000000 if X86_64 2177 help 2178 This value puts the alignment restrictions on physical address 2179 where kernel is loaded and run from. Kernel is compiled for an 2180 address which meets above alignment restriction. 2181 2182 If bootloader loads the kernel at a non-aligned address and 2183 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2184 address aligned to above value and run from there. 2185 2186 If bootloader loads the kernel at a non-aligned address and 2187 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2188 load address and decompress itself to the address it has been 2189 compiled for and run from there. The address for which kernel is 2190 compiled already meets above alignment restrictions. Hence the 2191 end result is that kernel runs from a physical address meeting 2192 above alignment restrictions. 2193 2194 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2195 this value must be a multiple of 0x200000. 2196 2197 Don't change this unless you know what you are doing. 2198 2199config DYNAMIC_MEMORY_LAYOUT 2200 bool 2201 help 2202 This option makes base addresses of vmalloc and vmemmap as well as 2203 __PAGE_OFFSET movable during boot. 2204 2205config RANDOMIZE_MEMORY 2206 bool "Randomize the kernel memory sections" 2207 depends on X86_64 2208 depends on RANDOMIZE_BASE 2209 select DYNAMIC_MEMORY_LAYOUT 2210 default RANDOMIZE_BASE 2211 help 2212 Randomizes the base virtual address of kernel memory sections 2213 (physical memory mapping, vmalloc & vmemmap). This security feature 2214 makes exploits relying on predictable memory locations less reliable. 2215 2216 The order of allocations remains unchanged. Entropy is generated in 2217 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2218 configuration have in average 30,000 different possible virtual 2219 addresses for each memory section. 2220 2221 If unsure, say Y. 2222 2223config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2224 hex "Physical memory mapping padding" if EXPERT 2225 depends on RANDOMIZE_MEMORY 2226 default "0xa" if MEMORY_HOTPLUG 2227 default "0x0" 2228 range 0x1 0x40 if MEMORY_HOTPLUG 2229 range 0x0 0x40 2230 help 2231 Define the padding in terabytes added to the existing physical 2232 memory size during kernel memory randomization. It is useful 2233 for memory hotplug support but reduces the entropy available for 2234 address randomization. 2235 2236 If unsure, leave at the default value. 2237 2238config HOTPLUG_CPU 2239 def_bool y 2240 depends on SMP 2241 2242config BOOTPARAM_HOTPLUG_CPU0 2243 bool "Set default setting of cpu0_hotpluggable" 2244 depends on HOTPLUG_CPU 2245 help 2246 Set whether default state of cpu0_hotpluggable is on or off. 2247 2248 Say Y here to enable CPU0 hotplug by default. If this switch 2249 is turned on, there is no need to give cpu0_hotplug kernel 2250 parameter and the CPU0 hotplug feature is enabled by default. 2251 2252 Please note: there are two known CPU0 dependencies if you want 2253 to enable the CPU0 hotplug feature either by this switch or by 2254 cpu0_hotplug kernel parameter. 2255 2256 First, resume from hibernate or suspend always starts from CPU0. 2257 So hibernate and suspend are prevented if CPU0 is offline. 2258 2259 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2260 offline if any interrupt can not migrate out of CPU0. There may 2261 be other CPU0 dependencies. 2262 2263 Please make sure the dependencies are under your control before 2264 you enable this feature. 2265 2266 Say N if you don't want to enable CPU0 hotplug feature by default. 2267 You still can enable the CPU0 hotplug feature at boot by kernel 2268 parameter cpu0_hotplug. 2269 2270config DEBUG_HOTPLUG_CPU0 2271 def_bool n 2272 prompt "Debug CPU0 hotplug" 2273 depends on HOTPLUG_CPU 2274 help 2275 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2276 soon as possible and boots up userspace with CPU0 offlined. User 2277 can online CPU0 back after boot time. 2278 2279 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2280 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2281 compilation or giving cpu0_hotplug kernel parameter at boot. 2282 2283 If unsure, say N. 2284 2285config COMPAT_VDSO 2286 def_bool n 2287 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2288 depends on COMPAT_32 2289 help 2290 Certain buggy versions of glibc will crash if they are 2291 presented with a 32-bit vDSO that is not mapped at the address 2292 indicated in its segment table. 2293 2294 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2295 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2296 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2297 the only released version with the bug, but OpenSUSE 9 2298 contains a buggy "glibc 2.3.2". 2299 2300 The symptom of the bug is that everything crashes on startup, saying: 2301 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2302 2303 Saying Y here changes the default value of the vdso32 boot 2304 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2305 This works around the glibc bug but hurts performance. 2306 2307 If unsure, say N: if you are compiling your own kernel, you 2308 are unlikely to be using a buggy version of glibc. 2309 2310choice 2311 prompt "vsyscall table for legacy applications" 2312 depends on X86_64 2313 default LEGACY_VSYSCALL_XONLY 2314 help 2315 Legacy user code that does not know how to find the vDSO expects 2316 to be able to issue three syscalls by calling fixed addresses in 2317 kernel space. Since this location is not randomized with ASLR, 2318 it can be used to assist security vulnerability exploitation. 2319 2320 This setting can be changed at boot time via the kernel command 2321 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2322 is deprecated and can only be enabled using the kernel command 2323 line. 2324 2325 On a system with recent enough glibc (2.14 or newer) and no 2326 static binaries, you can say None without a performance penalty 2327 to improve security. 2328 2329 If unsure, select "Emulate execution only". 2330 2331 config LEGACY_VSYSCALL_XONLY 2332 bool "Emulate execution only" 2333 help 2334 The kernel traps and emulates calls into the fixed vsyscall 2335 address mapping and does not allow reads. This 2336 configuration is recommended when userspace might use the 2337 legacy vsyscall area but support for legacy binary 2338 instrumentation of legacy code is not needed. It mitigates 2339 certain uses of the vsyscall area as an ASLR-bypassing 2340 buffer. 2341 2342 config LEGACY_VSYSCALL_NONE 2343 bool "None" 2344 help 2345 There will be no vsyscall mapping at all. This will 2346 eliminate any risk of ASLR bypass due to the vsyscall 2347 fixed address mapping. Attempts to use the vsyscalls 2348 will be reported to dmesg, so that either old or 2349 malicious userspace programs can be identified. 2350 2351endchoice 2352 2353config CMDLINE_BOOL 2354 bool "Built-in kernel command line" 2355 help 2356 Allow for specifying boot arguments to the kernel at 2357 build time. On some systems (e.g. embedded ones), it is 2358 necessary or convenient to provide some or all of the 2359 kernel boot arguments with the kernel itself (that is, 2360 to not rely on the boot loader to provide them.) 2361 2362 To compile command line arguments into the kernel, 2363 set this option to 'Y', then fill in the 2364 boot arguments in CONFIG_CMDLINE. 2365 2366 Systems with fully functional boot loaders (i.e. non-embedded) 2367 should leave this option set to 'N'. 2368 2369config CMDLINE 2370 string "Built-in kernel command string" 2371 depends on CMDLINE_BOOL 2372 default "" 2373 help 2374 Enter arguments here that should be compiled into the kernel 2375 image and used at boot time. If the boot loader provides a 2376 command line at boot time, it is appended to this string to 2377 form the full kernel command line, when the system boots. 2378 2379 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2380 change this behavior. 2381 2382 In most cases, the command line (whether built-in or provided 2383 by the boot loader) should specify the device for the root 2384 file system. 2385 2386config CMDLINE_OVERRIDE 2387 bool "Built-in command line overrides boot loader arguments" 2388 depends on CMDLINE_BOOL && CMDLINE != "" 2389 help 2390 Set this option to 'Y' to have the kernel ignore the boot loader 2391 command line, and use ONLY the built-in command line. 2392 2393 This is used to work around broken boot loaders. This should 2394 be set to 'N' under normal conditions. 2395 2396config MODIFY_LDT_SYSCALL 2397 bool "Enable the LDT (local descriptor table)" if EXPERT 2398 default y 2399 help 2400 Linux can allow user programs to install a per-process x86 2401 Local Descriptor Table (LDT) using the modify_ldt(2) system 2402 call. This is required to run 16-bit or segmented code such as 2403 DOSEMU or some Wine programs. It is also used by some very old 2404 threading libraries. 2405 2406 Enabling this feature adds a small amount of overhead to 2407 context switches and increases the low-level kernel attack 2408 surface. Disabling it removes the modify_ldt(2) system call. 2409 2410 Saying 'N' here may make sense for embedded or server kernels. 2411 2412config STRICT_SIGALTSTACK_SIZE 2413 bool "Enforce strict size checking for sigaltstack" 2414 depends on DYNAMIC_SIGFRAME 2415 help 2416 For historical reasons MINSIGSTKSZ is a constant which became 2417 already too small with AVX512 support. Add a mechanism to 2418 enforce strict checking of the sigaltstack size against the 2419 real size of the FPU frame. This option enables the check 2420 by default. It can also be controlled via the kernel command 2421 line option 'strict_sas_size' independent of this config 2422 switch. Enabling it might break existing applications which 2423 allocate a too small sigaltstack but 'work' because they 2424 never get a signal delivered. 2425 2426 Say 'N' unless you want to really enforce this check. 2427 2428source "kernel/livepatch/Kconfig" 2429 2430endmenu 2431 2432config CC_HAS_SLS 2433 def_bool $(cc-option,-mharden-sls=all) 2434 2435config CC_HAS_RETURN_THUNK 2436 def_bool $(cc-option,-mfunction-return=thunk-extern) 2437 2438menuconfig SPECULATION_MITIGATIONS 2439 bool "Mitigations for speculative execution vulnerabilities" 2440 default y 2441 help 2442 Say Y here to enable options which enable mitigations for 2443 speculative execution hardware vulnerabilities. 2444 2445 If you say N, all mitigations will be disabled. You really 2446 should know what you are doing to say so. 2447 2448if SPECULATION_MITIGATIONS 2449 2450config PAGE_TABLE_ISOLATION 2451 bool "Remove the kernel mapping in user mode" 2452 default y 2453 depends on (X86_64 || X86_PAE) 2454 help 2455 This feature reduces the number of hardware side channels by 2456 ensuring that the majority of kernel addresses are not mapped 2457 into userspace. 2458 2459 See Documentation/x86/pti.rst for more details. 2460 2461config RETPOLINE 2462 bool "Avoid speculative indirect branches in kernel" 2463 select OBJTOOL if HAVE_OBJTOOL 2464 default y 2465 help 2466 Compile kernel with the retpoline compiler options to guard against 2467 kernel-to-user data leaks by avoiding speculative indirect 2468 branches. Requires a compiler with -mindirect-branch=thunk-extern 2469 support for full protection. The kernel may run slower. 2470 2471config RETHUNK 2472 bool "Enable return-thunks" 2473 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2474 select OBJTOOL if HAVE_OBJTOOL 2475 default y if X86_64 2476 help 2477 Compile the kernel with the return-thunks compiler option to guard 2478 against kernel-to-user data leaks by avoiding return speculation. 2479 Requires a compiler with -mfunction-return=thunk-extern 2480 support for full protection. The kernel may run slower. 2481 2482config CPU_UNRET_ENTRY 2483 bool "Enable UNRET on kernel entry" 2484 depends on CPU_SUP_AMD && RETHUNK && X86_64 2485 default y 2486 help 2487 Compile the kernel with support for the retbleed=unret mitigation. 2488 2489config CPU_IBPB_ENTRY 2490 bool "Enable IBPB on kernel entry" 2491 depends on CPU_SUP_AMD && X86_64 2492 default y 2493 help 2494 Compile the kernel with support for the retbleed=ibpb mitigation. 2495 2496config CPU_IBRS_ENTRY 2497 bool "Enable IBRS on kernel entry" 2498 depends on CPU_SUP_INTEL && X86_64 2499 default y 2500 help 2501 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2502 This mitigates both spectre_v2 and retbleed at great cost to 2503 performance. 2504 2505config SLS 2506 bool "Mitigate Straight-Line-Speculation" 2507 depends on CC_HAS_SLS && X86_64 2508 select OBJTOOL if HAVE_OBJTOOL 2509 default n 2510 help 2511 Compile the kernel with straight-line-speculation options to guard 2512 against straight line speculation. The kernel image might be slightly 2513 larger. 2514 2515endif 2516 2517config ARCH_HAS_ADD_PAGES 2518 def_bool y 2519 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2520 2521config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2522 def_bool y 2523 2524menu "Power management and ACPI options" 2525 2526config ARCH_HIBERNATION_HEADER 2527 def_bool y 2528 depends on HIBERNATION 2529 2530source "kernel/power/Kconfig" 2531 2532source "drivers/acpi/Kconfig" 2533 2534config X86_APM_BOOT 2535 def_bool y 2536 depends on APM 2537 2538menuconfig APM 2539 tristate "APM (Advanced Power Management) BIOS support" 2540 depends on X86_32 && PM_SLEEP 2541 help 2542 APM is a BIOS specification for saving power using several different 2543 techniques. This is mostly useful for battery powered laptops with 2544 APM compliant BIOSes. If you say Y here, the system time will be 2545 reset after a RESUME operation, the /proc/apm device will provide 2546 battery status information, and user-space programs will receive 2547 notification of APM "events" (e.g. battery status change). 2548 2549 If you select "Y" here, you can disable actual use of the APM 2550 BIOS by passing the "apm=off" option to the kernel at boot time. 2551 2552 Note that the APM support is almost completely disabled for 2553 machines with more than one CPU. 2554 2555 In order to use APM, you will need supporting software. For location 2556 and more information, read <file:Documentation/power/apm-acpi.rst> 2557 and the Battery Powered Linux mini-HOWTO, available from 2558 <http://www.tldp.org/docs.html#howto>. 2559 2560 This driver does not spin down disk drives (see the hdparm(8) 2561 manpage ("man 8 hdparm") for that), and it doesn't turn off 2562 VESA-compliant "green" monitors. 2563 2564 This driver does not support the TI 4000M TravelMate and the ACER 2565 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2566 desktop machines also don't have compliant BIOSes, and this driver 2567 may cause those machines to panic during the boot phase. 2568 2569 Generally, if you don't have a battery in your machine, there isn't 2570 much point in using this driver and you should say N. If you get 2571 random kernel OOPSes or reboots that don't seem to be related to 2572 anything, try disabling/enabling this option (or disabling/enabling 2573 APM in your BIOS). 2574 2575 Some other things you should try when experiencing seemingly random, 2576 "weird" problems: 2577 2578 1) make sure that you have enough swap space and that it is 2579 enabled. 2580 2) pass the "no-hlt" option to the kernel 2581 3) switch on floating point emulation in the kernel and pass 2582 the "no387" option to the kernel 2583 4) pass the "floppy=nodma" option to the kernel 2584 5) pass the "mem=4M" option to the kernel (thereby disabling 2585 all but the first 4 MB of RAM) 2586 6) make sure that the CPU is not over clocked. 2587 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2588 8) disable the cache from your BIOS settings 2589 9) install a fan for the video card or exchange video RAM 2590 10) install a better fan for the CPU 2591 11) exchange RAM chips 2592 12) exchange the motherboard. 2593 2594 To compile this driver as a module, choose M here: the 2595 module will be called apm. 2596 2597if APM 2598 2599config APM_IGNORE_USER_SUSPEND 2600 bool "Ignore USER SUSPEND" 2601 help 2602 This option will ignore USER SUSPEND requests. On machines with a 2603 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2604 series notebooks, it is necessary to say Y because of a BIOS bug. 2605 2606config APM_DO_ENABLE 2607 bool "Enable PM at boot time" 2608 help 2609 Enable APM features at boot time. From page 36 of the APM BIOS 2610 specification: "When disabled, the APM BIOS does not automatically 2611 power manage devices, enter the Standby State, enter the Suspend 2612 State, or take power saving steps in response to CPU Idle calls." 2613 This driver will make CPU Idle calls when Linux is idle (unless this 2614 feature is turned off -- see "Do CPU IDLE calls", below). This 2615 should always save battery power, but more complicated APM features 2616 will be dependent on your BIOS implementation. You may need to turn 2617 this option off if your computer hangs at boot time when using APM 2618 support, or if it beeps continuously instead of suspending. Turn 2619 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2620 T400CDT. This is off by default since most machines do fine without 2621 this feature. 2622 2623config APM_CPU_IDLE 2624 depends on CPU_IDLE 2625 bool "Make CPU Idle calls when idle" 2626 help 2627 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2628 On some machines, this can activate improved power savings, such as 2629 a slowed CPU clock rate, when the machine is idle. These idle calls 2630 are made after the idle loop has run for some length of time (e.g., 2631 333 mS). On some machines, this will cause a hang at boot time or 2632 whenever the CPU becomes idle. (On machines with more than one CPU, 2633 this option does nothing.) 2634 2635config APM_DISPLAY_BLANK 2636 bool "Enable console blanking using APM" 2637 help 2638 Enable console blanking using the APM. Some laptops can use this to 2639 turn off the LCD backlight when the screen blanker of the Linux 2640 virtual console blanks the screen. Note that this is only used by 2641 the virtual console screen blanker, and won't turn off the backlight 2642 when using the X Window system. This also doesn't have anything to 2643 do with your VESA-compliant power-saving monitor. Further, this 2644 option doesn't work for all laptops -- it might not turn off your 2645 backlight at all, or it might print a lot of errors to the console, 2646 especially if you are using gpm. 2647 2648config APM_ALLOW_INTS 2649 bool "Allow interrupts during APM BIOS calls" 2650 help 2651 Normally we disable external interrupts while we are making calls to 2652 the APM BIOS as a measure to lessen the effects of a badly behaving 2653 BIOS implementation. The BIOS should reenable interrupts if it 2654 needs to. Unfortunately, some BIOSes do not -- especially those in 2655 many of the newer IBM Thinkpads. If you experience hangs when you 2656 suspend, try setting this to Y. Otherwise, say N. 2657 2658endif # APM 2659 2660source "drivers/cpufreq/Kconfig" 2661 2662source "drivers/cpuidle/Kconfig" 2663 2664source "drivers/idle/Kconfig" 2665 2666endmenu 2667 2668menu "Bus options (PCI etc.)" 2669 2670choice 2671 prompt "PCI access mode" 2672 depends on X86_32 && PCI 2673 default PCI_GOANY 2674 help 2675 On PCI systems, the BIOS can be used to detect the PCI devices and 2676 determine their configuration. However, some old PCI motherboards 2677 have BIOS bugs and may crash if this is done. Also, some embedded 2678 PCI-based systems don't have any BIOS at all. Linux can also try to 2679 detect the PCI hardware directly without using the BIOS. 2680 2681 With this option, you can specify how Linux should detect the 2682 PCI devices. If you choose "BIOS", the BIOS will be used, 2683 if you choose "Direct", the BIOS won't be used, and if you 2684 choose "MMConfig", then PCI Express MMCONFIG will be used. 2685 If you choose "Any", the kernel will try MMCONFIG, then the 2686 direct access method and falls back to the BIOS if that doesn't 2687 work. If unsure, go with the default, which is "Any". 2688 2689config PCI_GOBIOS 2690 bool "BIOS" 2691 2692config PCI_GOMMCONFIG 2693 bool "MMConfig" 2694 2695config PCI_GODIRECT 2696 bool "Direct" 2697 2698config PCI_GOOLPC 2699 bool "OLPC XO-1" 2700 depends on OLPC 2701 2702config PCI_GOANY 2703 bool "Any" 2704 2705endchoice 2706 2707config PCI_BIOS 2708 def_bool y 2709 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2710 2711# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2712config PCI_DIRECT 2713 def_bool y 2714 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2715 2716config PCI_MMCONFIG 2717 bool "Support mmconfig PCI config space access" if X86_64 2718 default y 2719 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2720 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2721 2722config PCI_OLPC 2723 def_bool y 2724 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2725 2726config PCI_XEN 2727 def_bool y 2728 depends on PCI && XEN 2729 2730config MMCONF_FAM10H 2731 def_bool y 2732 depends on X86_64 && PCI_MMCONFIG && ACPI 2733 2734config PCI_CNB20LE_QUIRK 2735 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2736 depends on PCI 2737 help 2738 Read the PCI windows out of the CNB20LE host bridge. This allows 2739 PCI hotplug to work on systems with the CNB20LE chipset which do 2740 not have ACPI. 2741 2742 There's no public spec for this chipset, and this functionality 2743 is known to be incomplete. 2744 2745 You should say N unless you know you need this. 2746 2747config ISA_BUS 2748 bool "ISA bus support on modern systems" if EXPERT 2749 help 2750 Expose ISA bus device drivers and options available for selection and 2751 configuration. Enable this option if your target machine has an ISA 2752 bus. ISA is an older system, displaced by PCI and newer bus 2753 architectures -- if your target machine is modern, it probably does 2754 not have an ISA bus. 2755 2756 If unsure, say N. 2757 2758# x86_64 have no ISA slots, but can have ISA-style DMA. 2759config ISA_DMA_API 2760 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2761 default y 2762 help 2763 Enables ISA-style DMA support for devices requiring such controllers. 2764 If unsure, say Y. 2765 2766if X86_32 2767 2768config ISA 2769 bool "ISA support" 2770 help 2771 Find out whether you have ISA slots on your motherboard. ISA is the 2772 name of a bus system, i.e. the way the CPU talks to the other stuff 2773 inside your box. Other bus systems are PCI, EISA, MicroChannel 2774 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2775 newer boards don't support it. If you have ISA, say Y, otherwise N. 2776 2777config SCx200 2778 tristate "NatSemi SCx200 support" 2779 help 2780 This provides basic support for National Semiconductor's 2781 (now AMD's) Geode processors. The driver probes for the 2782 PCI-IDs of several on-chip devices, so its a good dependency 2783 for other scx200_* drivers. 2784 2785 If compiled as a module, the driver is named scx200. 2786 2787config SCx200HR_TIMER 2788 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2789 depends on SCx200 2790 default y 2791 help 2792 This driver provides a clocksource built upon the on-chip 2793 27MHz high-resolution timer. Its also a workaround for 2794 NSC Geode SC-1100's buggy TSC, which loses time when the 2795 processor goes idle (as is done by the scheduler). The 2796 other workaround is idle=poll boot option. 2797 2798config OLPC 2799 bool "One Laptop Per Child support" 2800 depends on !X86_PAE 2801 select GPIOLIB 2802 select OF 2803 select OF_PROMTREE 2804 select IRQ_DOMAIN 2805 select OLPC_EC 2806 help 2807 Add support for detecting the unique features of the OLPC 2808 XO hardware. 2809 2810config OLPC_XO1_PM 2811 bool "OLPC XO-1 Power Management" 2812 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2813 help 2814 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2815 2816config OLPC_XO1_RTC 2817 bool "OLPC XO-1 Real Time Clock" 2818 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2819 help 2820 Add support for the XO-1 real time clock, which can be used as a 2821 programmable wakeup source. 2822 2823config OLPC_XO1_SCI 2824 bool "OLPC XO-1 SCI extras" 2825 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2826 depends on INPUT=y 2827 select POWER_SUPPLY 2828 help 2829 Add support for SCI-based features of the OLPC XO-1 laptop: 2830 - EC-driven system wakeups 2831 - Power button 2832 - Ebook switch 2833 - Lid switch 2834 - AC adapter status updates 2835 - Battery status updates 2836 2837config OLPC_XO15_SCI 2838 bool "OLPC XO-1.5 SCI extras" 2839 depends on OLPC && ACPI 2840 select POWER_SUPPLY 2841 help 2842 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2843 - EC-driven system wakeups 2844 - AC adapter status updates 2845 - Battery status updates 2846 2847config ALIX 2848 bool "PCEngines ALIX System Support (LED setup)" 2849 select GPIOLIB 2850 help 2851 This option enables system support for the PCEngines ALIX. 2852 At present this just sets up LEDs for GPIO control on 2853 ALIX2/3/6 boards. However, other system specific setup should 2854 get added here. 2855 2856 Note: You must still enable the drivers for GPIO and LED support 2857 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2858 2859 Note: You have to set alix.force=1 for boards with Award BIOS. 2860 2861config NET5501 2862 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2863 select GPIOLIB 2864 help 2865 This option enables system support for the Soekris Engineering net5501. 2866 2867config GEOS 2868 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2869 select GPIOLIB 2870 depends on DMI 2871 help 2872 This option enables system support for the Traverse Technologies GEOS. 2873 2874config TS5500 2875 bool "Technologic Systems TS-5500 platform support" 2876 depends on MELAN 2877 select CHECK_SIGNATURE 2878 select NEW_LEDS 2879 select LEDS_CLASS 2880 help 2881 This option enables system support for the Technologic Systems TS-5500. 2882 2883endif # X86_32 2884 2885config AMD_NB 2886 def_bool y 2887 depends on CPU_SUP_AMD && PCI 2888 2889endmenu 2890 2891menu "Binary Emulations" 2892 2893config IA32_EMULATION 2894 bool "IA32 Emulation" 2895 depends on X86_64 2896 select ARCH_WANT_OLD_COMPAT_IPC 2897 select BINFMT_ELF 2898 select COMPAT_OLD_SIGACTION 2899 help 2900 Include code to run legacy 32-bit programs under a 2901 64-bit kernel. You should likely turn this on, unless you're 2902 100% sure that you don't have any 32-bit programs left. 2903 2904config X86_X32_ABI 2905 bool "x32 ABI for 64-bit mode" 2906 depends on X86_64 2907 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2908 # compressed debug sections to x86_x32 properly: 2909 # https://github.com/ClangBuiltLinux/linux/issues/514 2910 # https://github.com/ClangBuiltLinux/linux/issues/1141 2911 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 2912 help 2913 Include code to run binaries for the x32 native 32-bit ABI 2914 for 64-bit processors. An x32 process gets access to the 2915 full 64-bit register file and wide data path while leaving 2916 pointers at 32 bits for smaller memory footprint. 2917 2918config COMPAT_32 2919 def_bool y 2920 depends on IA32_EMULATION || X86_32 2921 select HAVE_UID16 2922 select OLD_SIGSUSPEND3 2923 2924config COMPAT 2925 def_bool y 2926 depends on IA32_EMULATION || X86_X32_ABI 2927 2928config COMPAT_FOR_U64_ALIGNMENT 2929 def_bool y 2930 depends on COMPAT 2931 2932endmenu 2933 2934config HAVE_ATOMIC_IOMAP 2935 def_bool y 2936 depends on X86_32 2937 2938source "arch/x86/kvm/Kconfig" 2939 2940source "arch/x86/Kconfig.assembler" 2941