1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_USE_CMPXCHG_LOCKREF 31 select HAVE_ARCH_SOFT_DIRTY 32 select MODULES_USE_ELF_RELA 33 select NEED_DMA_MAP_STATE 34 select SWIOTLB 35 select ARCH_HAS_ELFCORE_COMPAT 36 select ZONE_DMA32 37 38config FORCE_DYNAMIC_FTRACE 39 def_bool y 40 depends on X86_32 41 depends on FUNCTION_TRACER 42 select DYNAMIC_FTRACE 43 help 44 We keep the static function tracing (!DYNAMIC_FTRACE) around 45 in order to test the non static function tracing in the 46 generic code, as other architectures still use it. But we 47 only need to keep it around for x86_64. No need to keep it 48 for x86_32. For x86_32, force DYNAMIC_FTRACE. 49# 50# Arch settings 51# 52# ( Note that options that are marked 'if X86_64' could in principle be 53# ported to 32-bit as well. ) 54# 55config X86 56 def_bool y 57 # 58 # Note: keep this list sorted alphabetically 59 # 60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 62 select ARCH_32BIT_OFF_T if X86_32 63 select ARCH_CLOCKSOURCE_INIT 64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 71 select ARCH_HAS_CACHE_LINE_SIZE 72 select ARCH_HAS_CURRENT_STACK_POINTER 73 select ARCH_HAS_DEBUG_VIRTUAL 74 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 75 select ARCH_HAS_DEVMEM_IS_ALLOWED 76 select ARCH_HAS_EARLY_DEBUG if KGDB 77 select ARCH_HAS_ELF_RANDOMIZE 78 select ARCH_HAS_FAST_MULTIPLIER 79 select ARCH_HAS_FORTIFY_SOURCE 80 select ARCH_HAS_GCOV_PROFILE_ALL 81 select ARCH_HAS_KCOV if X86_64 82 select ARCH_HAS_MEM_ENCRYPT 83 select ARCH_HAS_MEMBARRIER_SYNC_CORE 84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 85 select ARCH_HAS_PMEM_API if X86_64 86 select ARCH_HAS_PTE_DEVMAP if X86_64 87 select ARCH_HAS_PTE_SPECIAL 88 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 89 select ARCH_HAS_COPY_MC if X86_64 90 select ARCH_HAS_SET_MEMORY 91 select ARCH_HAS_SET_DIRECT_MAP 92 select ARCH_HAS_STRICT_KERNEL_RWX 93 select ARCH_HAS_STRICT_MODULE_RWX 94 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 95 select ARCH_HAS_SYSCALL_WRAPPER 96 select ARCH_HAS_UBSAN_SANITIZE_ALL 97 select ARCH_HAS_DEBUG_WX 98 select ARCH_HAS_ZONE_DMA_SET if EXPERT 99 select ARCH_HAVE_NMI_SAFE_CMPXCHG 100 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 101 select ARCH_MIGHT_HAVE_PC_PARPORT 102 select ARCH_MIGHT_HAVE_PC_SERIO 103 select ARCH_STACKWALK 104 select ARCH_SUPPORTS_ACPI 105 select ARCH_SUPPORTS_ATOMIC_RMW 106 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 107 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 108 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 109 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 110 select ARCH_SUPPORTS_CFI_CLANG if X86_64 111 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 112 select ARCH_SUPPORTS_LTO_CLANG 113 select ARCH_SUPPORTS_LTO_CLANG_THIN 114 select ARCH_USE_BUILTIN_BSWAP 115 select ARCH_USE_MEMTEST 116 select ARCH_USE_QUEUED_RWLOCKS 117 select ARCH_USE_QUEUED_SPINLOCKS 118 select ARCH_USE_SYM_ANNOTATIONS 119 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 120 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 121 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 122 select ARCH_WANTS_NO_INSTR 123 select ARCH_WANT_GENERAL_HUGETLB 124 select ARCH_WANT_HUGE_PMD_SHARE 125 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64 126 select ARCH_WANT_LD_ORPHAN_WARN 127 select ARCH_WANTS_THP_SWAP if X86_64 128 select ARCH_HAS_PARANOID_L1D_FLUSH 129 select BUILDTIME_TABLE_SORT 130 select CLKEVT_I8253 131 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 132 select CLOCKSOURCE_WATCHDOG 133 select DCACHE_WORD_ACCESS 134 select DYNAMIC_SIGFRAME 135 select EDAC_ATOMIC_SCRUB 136 select EDAC_SUPPORT 137 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 138 select GENERIC_CLOCKEVENTS_MIN_ADJUST 139 select GENERIC_CMOS_UPDATE 140 select GENERIC_CPU_AUTOPROBE 141 select GENERIC_CPU_VULNERABILITIES 142 select GENERIC_EARLY_IOREMAP 143 select GENERIC_ENTRY 144 select GENERIC_IOMAP 145 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 146 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 147 select GENERIC_IRQ_MIGRATION if SMP 148 select GENERIC_IRQ_PROBE 149 select GENERIC_IRQ_RESERVATION_MODE 150 select GENERIC_IRQ_SHOW 151 select GENERIC_PENDING_IRQ if SMP 152 select GENERIC_PTDUMP 153 select GENERIC_SMP_IDLE_THREAD 154 select GENERIC_TIME_VSYSCALL 155 select GENERIC_GETTIMEOFDAY 156 select GENERIC_VDSO_TIME_NS 157 select GUP_GET_PTE_LOW_HIGH if X86_PAE 158 select HARDIRQS_SW_RESEND 159 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 160 select HAVE_ACPI_APEI if ACPI 161 select HAVE_ACPI_APEI_NMI if ACPI 162 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 163 select HAVE_ARCH_AUDITSYSCALL 164 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 165 select HAVE_ARCH_HUGE_VMALLOC if X86_64 166 select HAVE_ARCH_JUMP_LABEL 167 select HAVE_ARCH_JUMP_LABEL_RELATIVE 168 select HAVE_ARCH_KASAN if X86_64 169 select HAVE_ARCH_KASAN_VMALLOC if X86_64 170 select HAVE_ARCH_KFENCE 171 select HAVE_ARCH_KGDB 172 select HAVE_ARCH_MMAP_RND_BITS if MMU 173 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 174 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 175 select HAVE_ARCH_PREL32_RELOCATIONS 176 select HAVE_ARCH_SECCOMP_FILTER 177 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 178 select HAVE_ARCH_STACKLEAK 179 select HAVE_ARCH_TRACEHOOK 180 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 181 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 182 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 183 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 184 select HAVE_ARCH_VMAP_STACK if X86_64 185 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 186 select HAVE_ARCH_WITHIN_STACK_FRAMES 187 select HAVE_ASM_MODVERSIONS 188 select HAVE_CMPXCHG_DOUBLE 189 select HAVE_CMPXCHG_LOCAL 190 select HAVE_CONTEXT_TRACKING_USER if X86_64 191 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 192 select HAVE_C_RECORDMCOUNT 193 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 194 select HAVE_BUILDTIME_MCOUNT_SORT 195 select HAVE_DEBUG_KMEMLEAK 196 select HAVE_DMA_CONTIGUOUS 197 select HAVE_DYNAMIC_FTRACE 198 select HAVE_DYNAMIC_FTRACE_WITH_REGS 199 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 200 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 201 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 202 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 203 select HAVE_EBPF_JIT 204 select HAVE_EFFICIENT_UNALIGNED_ACCESS 205 select HAVE_EISA 206 select HAVE_EXIT_THREAD 207 select HAVE_FAST_GUP 208 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 209 select HAVE_FTRACE_MCOUNT_RECORD 210 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 211 select HAVE_FUNCTION_TRACER 212 select HAVE_GCC_PLUGINS 213 select HAVE_HW_BREAKPOINT 214 select HAVE_IOREMAP_PROT 215 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 216 select HAVE_IRQ_TIME_ACCOUNTING 217 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 218 select HAVE_KERNEL_BZIP2 219 select HAVE_KERNEL_GZIP 220 select HAVE_KERNEL_LZ4 221 select HAVE_KERNEL_LZMA 222 select HAVE_KERNEL_LZO 223 select HAVE_KERNEL_XZ 224 select HAVE_KERNEL_ZSTD 225 select HAVE_KPROBES 226 select HAVE_KPROBES_ON_FTRACE 227 select HAVE_FUNCTION_ERROR_INJECTION 228 select HAVE_KRETPROBES 229 select HAVE_RETHOOK 230 select HAVE_KVM 231 select HAVE_LIVEPATCH if X86_64 232 select HAVE_MIXED_BREAKPOINTS_REGS 233 select HAVE_MOD_ARCH_SPECIFIC 234 select HAVE_MOVE_PMD 235 select HAVE_MOVE_PUD 236 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 237 select HAVE_NMI 238 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 239 select HAVE_OBJTOOL if X86_64 240 select HAVE_OPTPROBES 241 select HAVE_PCSPKR_PLATFORM 242 select HAVE_PERF_EVENTS 243 select HAVE_PERF_EVENTS_NMI 244 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 245 select HAVE_PCI 246 select HAVE_PERF_REGS 247 select HAVE_PERF_USER_STACK_DUMP 248 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 249 select MMU_GATHER_MERGE_VMAS 250 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 251 select HAVE_REGS_AND_STACK_ACCESS_API 252 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 253 select HAVE_FUNCTION_ARG_ACCESS_API 254 select HAVE_SETUP_PER_CPU_AREA 255 select HAVE_SOFTIRQ_ON_OWN_STACK 256 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 257 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 258 select HAVE_STATIC_CALL 259 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 260 select HAVE_PREEMPT_DYNAMIC_CALL 261 select HAVE_RSEQ 262 select HAVE_RUST if X86_64 263 select HAVE_SYSCALL_TRACEPOINTS 264 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 265 select HAVE_UNSTABLE_SCHED_CLOCK 266 select HAVE_USER_RETURN_NOTIFIER 267 select HAVE_GENERIC_VDSO 268 select HOTPLUG_SMT if SMP 269 select IRQ_FORCED_THREADING 270 select NEED_PER_CPU_EMBED_FIRST_CHUNK 271 select NEED_PER_CPU_PAGE_FIRST_CHUNK 272 select NEED_SG_DMA_LENGTH 273 select PCI_DOMAINS if PCI 274 select PCI_LOCKLESS_CONFIG if PCI 275 select PERF_EVENTS 276 select RTC_LIB 277 select RTC_MC146818_LIB 278 select SPARSE_IRQ 279 select SRCU 280 select SYSCTL_EXCEPTION_TRACE 281 select THREAD_INFO_IN_TASK 282 select TRACE_IRQFLAGS_SUPPORT 283 select TRACE_IRQFLAGS_NMI_SUPPORT 284 select USER_STACKTRACE_SUPPORT 285 select HAVE_ARCH_KCSAN if X86_64 286 select X86_FEATURE_NAMES if PROC_FS 287 select PROC_PID_ARCH_STATUS if PROC_FS 288 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 289 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 290 291config INSTRUCTION_DECODER 292 def_bool y 293 depends on KPROBES || PERF_EVENTS || UPROBES 294 295config OUTPUT_FORMAT 296 string 297 default "elf32-i386" if X86_32 298 default "elf64-x86-64" if X86_64 299 300config LOCKDEP_SUPPORT 301 def_bool y 302 303config STACKTRACE_SUPPORT 304 def_bool y 305 306config MMU 307 def_bool y 308 309config ARCH_MMAP_RND_BITS_MIN 310 default 28 if 64BIT 311 default 8 312 313config ARCH_MMAP_RND_BITS_MAX 314 default 32 if 64BIT 315 default 16 316 317config ARCH_MMAP_RND_COMPAT_BITS_MIN 318 default 8 319 320config ARCH_MMAP_RND_COMPAT_BITS_MAX 321 default 16 322 323config SBUS 324 bool 325 326config GENERIC_ISA_DMA 327 def_bool y 328 depends on ISA_DMA_API 329 330config GENERIC_BUG 331 def_bool y 332 depends on BUG 333 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 334 335config GENERIC_BUG_RELATIVE_POINTERS 336 bool 337 338config ARCH_MAY_HAVE_PC_FDC 339 def_bool y 340 depends on ISA_DMA_API 341 342config GENERIC_CALIBRATE_DELAY 343 def_bool y 344 345config ARCH_HAS_CPU_RELAX 346 def_bool y 347 348config ARCH_HIBERNATION_POSSIBLE 349 def_bool y 350 351config ARCH_NR_GPIO 352 int 353 default 1024 if X86_64 354 default 512 355 356config ARCH_SUSPEND_POSSIBLE 357 def_bool y 358 359config AUDIT_ARCH 360 def_bool y if X86_64 361 362config KASAN_SHADOW_OFFSET 363 hex 364 depends on KASAN 365 default 0xdffffc0000000000 366 367config HAVE_INTEL_TXT 368 def_bool y 369 depends on INTEL_IOMMU && ACPI 370 371config X86_32_SMP 372 def_bool y 373 depends on X86_32 && SMP 374 375config X86_64_SMP 376 def_bool y 377 depends on X86_64 && SMP 378 379config ARCH_SUPPORTS_UPROBES 380 def_bool y 381 382config FIX_EARLYCON_MEM 383 def_bool y 384 385config DYNAMIC_PHYSICAL_MASK 386 bool 387 388config PGTABLE_LEVELS 389 int 390 default 5 if X86_5LEVEL 391 default 4 if X86_64 392 default 3 if X86_PAE 393 default 2 394 395config CC_HAS_SANE_STACKPROTECTOR 396 bool 397 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 398 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 399 help 400 We have to make sure stack protector is unconditionally disabled if 401 the compiler produces broken code or if it does not let us control 402 the segment on 32-bit kernels. 403 404menu "Processor type and features" 405 406config SMP 407 bool "Symmetric multi-processing support" 408 help 409 This enables support for systems with more than one CPU. If you have 410 a system with only one CPU, say N. If you have a system with more 411 than one CPU, say Y. 412 413 If you say N here, the kernel will run on uni- and multiprocessor 414 machines, but will use only one CPU of a multiprocessor machine. If 415 you say Y here, the kernel will run on many, but not all, 416 uniprocessor machines. On a uniprocessor machine, the kernel 417 will run faster if you say N here. 418 419 Note that if you say Y here and choose architecture "586" or 420 "Pentium" under "Processor family", the kernel will not work on 486 421 architectures. Similarly, multiprocessor kernels for the "PPro" 422 architecture may not work on all Pentium based boards. 423 424 People using multiprocessor machines who say Y here should also say 425 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 426 Management" code will be disabled if you say Y here. 427 428 See also <file:Documentation/x86/i386/IO-APIC.rst>, 429 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 430 <http://www.tldp.org/docs.html#howto>. 431 432 If you don't know what to do here, say N. 433 434config X86_FEATURE_NAMES 435 bool "Processor feature human-readable names" if EMBEDDED 436 default y 437 help 438 This option compiles in a table of x86 feature bits and corresponding 439 names. This is required to support /proc/cpuinfo and a few kernel 440 messages. You can disable this to save space, at the expense of 441 making those few kernel messages show numeric feature bits instead. 442 443 If in doubt, say Y. 444 445config X86_X2APIC 446 bool "Support x2apic" 447 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 448 help 449 This enables x2apic support on CPUs that have this feature. 450 451 This allows 32-bit apic IDs (so it can support very large systems), 452 and accesses the local apic via MSRs not via mmio. 453 454 If you don't know what to do here, say N. 455 456config X86_MPPARSE 457 bool "Enable MPS table" if ACPI 458 default y 459 depends on X86_LOCAL_APIC 460 help 461 For old smp systems that do not have proper acpi support. Newer systems 462 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 463 464config GOLDFISH 465 def_bool y 466 depends on X86_GOLDFISH 467 468config X86_CPU_RESCTRL 469 bool "x86 CPU resource control support" 470 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 471 select KERNFS 472 select PROC_CPU_RESCTRL if PROC_FS 473 help 474 Enable x86 CPU resource control support. 475 476 Provide support for the allocation and monitoring of system resources 477 usage by the CPU. 478 479 Intel calls this Intel Resource Director Technology 480 (Intel(R) RDT). More information about RDT can be found in the 481 Intel x86 Architecture Software Developer Manual. 482 483 AMD calls this AMD Platform Quality of Service (AMD QoS). 484 More information about AMD QoS can be found in the AMD64 Technology 485 Platform Quality of Service Extensions manual. 486 487 Say N if unsure. 488 489if X86_32 490config X86_BIGSMP 491 bool "Support for big SMP systems with more than 8 CPUs" 492 depends on SMP 493 help 494 This option is needed for the systems that have more than 8 CPUs. 495 496config X86_EXTENDED_PLATFORM 497 bool "Support for extended (non-PC) x86 platforms" 498 default y 499 help 500 If you disable this option then the kernel will only support 501 standard PC platforms. (which covers the vast majority of 502 systems out there.) 503 504 If you enable this option then you'll be able to select support 505 for the following (non-PC) 32 bit x86 platforms: 506 Goldfish (Android emulator) 507 AMD Elan 508 RDC R-321x SoC 509 SGI 320/540 (Visual Workstation) 510 STA2X11-based (e.g. Northville) 511 Moorestown MID devices 512 513 If you have one of these systems, or if you want to build a 514 generic distribution kernel, say Y here - otherwise say N. 515endif # X86_32 516 517if X86_64 518config X86_EXTENDED_PLATFORM 519 bool "Support for extended (non-PC) x86 platforms" 520 default y 521 help 522 If you disable this option then the kernel will only support 523 standard PC platforms. (which covers the vast majority of 524 systems out there.) 525 526 If you enable this option then you'll be able to select support 527 for the following (non-PC) 64 bit x86 platforms: 528 Numascale NumaChip 529 ScaleMP vSMP 530 SGI Ultraviolet 531 532 If you have one of these systems, or if you want to build a 533 generic distribution kernel, say Y here - otherwise say N. 534endif # X86_64 535# This is an alphabetically sorted list of 64 bit extended platforms 536# Please maintain the alphabetic order if and when there are additions 537config X86_NUMACHIP 538 bool "Numascale NumaChip" 539 depends on X86_64 540 depends on X86_EXTENDED_PLATFORM 541 depends on NUMA 542 depends on SMP 543 depends on X86_X2APIC 544 depends on PCI_MMCONFIG 545 help 546 Adds support for Numascale NumaChip large-SMP systems. Needed to 547 enable more than ~168 cores. 548 If you don't have one of these, you should say N here. 549 550config X86_VSMP 551 bool "ScaleMP vSMP" 552 select HYPERVISOR_GUEST 553 select PARAVIRT 554 depends on X86_64 && PCI 555 depends on X86_EXTENDED_PLATFORM 556 depends on SMP 557 help 558 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 559 supposed to run on these EM64T-based machines. Only choose this option 560 if you have one of these machines. 561 562config X86_UV 563 bool "SGI Ultraviolet" 564 depends on X86_64 565 depends on X86_EXTENDED_PLATFORM 566 depends on NUMA 567 depends on EFI 568 depends on KEXEC_CORE 569 depends on X86_X2APIC 570 depends on PCI 571 help 572 This option is needed in order to support SGI Ultraviolet systems. 573 If you don't have one of these, you should say N here. 574 575# Following is an alphabetically sorted list of 32 bit extended platforms 576# Please maintain the alphabetic order if and when there are additions 577 578config X86_GOLDFISH 579 bool "Goldfish (Virtual Platform)" 580 depends on X86_EXTENDED_PLATFORM 581 help 582 Enable support for the Goldfish virtual platform used primarily 583 for Android development. Unless you are building for the Android 584 Goldfish emulator say N here. 585 586config X86_INTEL_CE 587 bool "CE4100 TV platform" 588 depends on PCI 589 depends on PCI_GODIRECT 590 depends on X86_IO_APIC 591 depends on X86_32 592 depends on X86_EXTENDED_PLATFORM 593 select X86_REBOOTFIXUPS 594 select OF 595 select OF_EARLY_FLATTREE 596 help 597 Select for the Intel CE media processor (CE4100) SOC. 598 This option compiles in support for the CE4100 SOC for settop 599 boxes and media devices. 600 601config X86_INTEL_MID 602 bool "Intel MID platform support" 603 depends on X86_EXTENDED_PLATFORM 604 depends on X86_PLATFORM_DEVICES 605 depends on PCI 606 depends on X86_64 || (PCI_GOANY && X86_32) 607 depends on X86_IO_APIC 608 select I2C 609 select DW_APB_TIMER 610 select INTEL_SCU_PCI 611 help 612 Select to build a kernel capable of supporting Intel MID (Mobile 613 Internet Device) platform systems which do not have the PCI legacy 614 interfaces. If you are building for a PC class system say N here. 615 616 Intel MID platforms are based on an Intel processor and chipset which 617 consume less power than most of the x86 derivatives. 618 619config X86_INTEL_QUARK 620 bool "Intel Quark platform support" 621 depends on X86_32 622 depends on X86_EXTENDED_PLATFORM 623 depends on X86_PLATFORM_DEVICES 624 depends on X86_TSC 625 depends on PCI 626 depends on PCI_GOANY 627 depends on X86_IO_APIC 628 select IOSF_MBI 629 select INTEL_IMR 630 select COMMON_CLK 631 help 632 Select to include support for Quark X1000 SoC. 633 Say Y here if you have a Quark based system such as the Arduino 634 compatible Intel Galileo. 635 636config X86_INTEL_LPSS 637 bool "Intel Low Power Subsystem Support" 638 depends on X86 && ACPI && PCI 639 select COMMON_CLK 640 select PINCTRL 641 select IOSF_MBI 642 help 643 Select to build support for Intel Low Power Subsystem such as 644 found on Intel Lynxpoint PCH. Selecting this option enables 645 things like clock tree (common clock framework) and pincontrol 646 which are needed by the LPSS peripheral drivers. 647 648config X86_AMD_PLATFORM_DEVICE 649 bool "AMD ACPI2Platform devices support" 650 depends on ACPI 651 select COMMON_CLK 652 select PINCTRL 653 help 654 Select to interpret AMD specific ACPI device to platform device 655 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 656 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 657 implemented under PINCTRL subsystem. 658 659config IOSF_MBI 660 tristate "Intel SoC IOSF Sideband support for SoC platforms" 661 depends on PCI 662 help 663 This option enables sideband register access support for Intel SoC 664 platforms. On these platforms the IOSF sideband is used in lieu of 665 MSR's for some register accesses, mostly but not limited to thermal 666 and power. Drivers may query the availability of this device to 667 determine if they need the sideband in order to work on these 668 platforms. The sideband is available on the following SoC products. 669 This list is not meant to be exclusive. 670 - BayTrail 671 - Braswell 672 - Quark 673 674 You should say Y if you are running a kernel on one of these SoC's. 675 676config IOSF_MBI_DEBUG 677 bool "Enable IOSF sideband access through debugfs" 678 depends on IOSF_MBI && DEBUG_FS 679 help 680 Select this option to expose the IOSF sideband access registers (MCR, 681 MDR, MCRX) through debugfs to write and read register information from 682 different units on the SoC. This is most useful for obtaining device 683 state information for debug and analysis. As this is a general access 684 mechanism, users of this option would have specific knowledge of the 685 device they want to access. 686 687 If you don't require the option or are in doubt, say N. 688 689config X86_RDC321X 690 bool "RDC R-321x SoC" 691 depends on X86_32 692 depends on X86_EXTENDED_PLATFORM 693 select M486 694 select X86_REBOOTFIXUPS 695 help 696 This option is needed for RDC R-321x system-on-chip, also known 697 as R-8610-(G). 698 If you don't have one of these chips, you should say N here. 699 700config X86_32_NON_STANDARD 701 bool "Support non-standard 32-bit SMP architectures" 702 depends on X86_32 && SMP 703 depends on X86_EXTENDED_PLATFORM 704 help 705 This option compiles in the bigsmp and STA2X11 default 706 subarchitectures. It is intended for a generic binary 707 kernel. If you select them all, kernel will probe it one by 708 one and will fallback to default. 709 710# Alphabetically sorted list of Non standard 32 bit platforms 711 712config X86_SUPPORTS_MEMORY_FAILURE 713 def_bool y 714 # MCE code calls memory_failure(): 715 depends on X86_MCE 716 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 717 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 718 depends on X86_64 || !SPARSEMEM 719 select ARCH_SUPPORTS_MEMORY_FAILURE 720 721config STA2X11 722 bool "STA2X11 Companion Chip Support" 723 depends on X86_32_NON_STANDARD && PCI 724 select SWIOTLB 725 select MFD_STA2X11 726 select GPIOLIB 727 help 728 This adds support for boards based on the STA2X11 IO-Hub, 729 a.k.a. "ConneXt". The chip is used in place of the standard 730 PC chipset, so all "standard" peripherals are missing. If this 731 option is selected the kernel will still be able to boot on 732 standard PC machines. 733 734config X86_32_IRIS 735 tristate "Eurobraille/Iris poweroff module" 736 depends on X86_32 737 help 738 The Iris machines from EuroBraille do not have APM or ACPI support 739 to shut themselves down properly. A special I/O sequence is 740 needed to do so, which is what this module does at 741 kernel shutdown. 742 743 This is only for Iris machines from EuroBraille. 744 745 If unused, say N. 746 747config SCHED_OMIT_FRAME_POINTER 748 def_bool y 749 prompt "Single-depth WCHAN output" 750 depends on X86 751 help 752 Calculate simpler /proc/<PID>/wchan values. If this option 753 is disabled then wchan values will recurse back to the 754 caller function. This provides more accurate wchan values, 755 at the expense of slightly more scheduling overhead. 756 757 If in doubt, say "Y". 758 759menuconfig HYPERVISOR_GUEST 760 bool "Linux guest support" 761 help 762 Say Y here to enable options for running Linux under various hyper- 763 visors. This option enables basic hypervisor detection and platform 764 setup. 765 766 If you say N, all options in this submenu will be skipped and 767 disabled, and Linux guest support won't be built in. 768 769if HYPERVISOR_GUEST 770 771config PARAVIRT 772 bool "Enable paravirtualization code" 773 depends on HAVE_STATIC_CALL 774 help 775 This changes the kernel so it can modify itself when it is run 776 under a hypervisor, potentially improving performance significantly 777 over full virtualization. However, when run without a hypervisor 778 the kernel is theoretically slower and slightly larger. 779 780config PARAVIRT_XXL 781 bool 782 783config PARAVIRT_DEBUG 784 bool "paravirt-ops debugging" 785 depends on PARAVIRT && DEBUG_KERNEL 786 help 787 Enable to debug paravirt_ops internals. Specifically, BUG if 788 a paravirt_op is missing when it is called. 789 790config PARAVIRT_SPINLOCKS 791 bool "Paravirtualization layer for spinlocks" 792 depends on PARAVIRT && SMP 793 help 794 Paravirtualized spinlocks allow a pvops backend to replace the 795 spinlock implementation with something virtualization-friendly 796 (for example, block the virtual CPU rather than spinning). 797 798 It has a minimal impact on native kernels and gives a nice performance 799 benefit on paravirtualized KVM / Xen kernels. 800 801 If you are unsure how to answer this question, answer Y. 802 803config X86_HV_CALLBACK_VECTOR 804 def_bool n 805 806source "arch/x86/xen/Kconfig" 807 808config KVM_GUEST 809 bool "KVM Guest support (including kvmclock)" 810 depends on PARAVIRT 811 select PARAVIRT_CLOCK 812 select ARCH_CPUIDLE_HALTPOLL 813 select X86_HV_CALLBACK_VECTOR 814 default y 815 help 816 This option enables various optimizations for running under the KVM 817 hypervisor. It includes a paravirtualized clock, so that instead 818 of relying on a PIT (or probably other) emulation by the 819 underlying device model, the host provides the guest with 820 timing infrastructure such as time of day, and system time 821 822config ARCH_CPUIDLE_HALTPOLL 823 def_bool n 824 prompt "Disable host haltpoll when loading haltpoll driver" 825 help 826 If virtualized under KVM, disable host haltpoll. 827 828config PVH 829 bool "Support for running PVH guests" 830 help 831 This option enables the PVH entry point for guest virtual machines 832 as specified in the x86/HVM direct boot ABI. 833 834config PARAVIRT_TIME_ACCOUNTING 835 bool "Paravirtual steal time accounting" 836 depends on PARAVIRT 837 help 838 Select this option to enable fine granularity task steal time 839 accounting. Time spent executing other tasks in parallel with 840 the current vCPU is discounted from the vCPU power. To account for 841 that, there can be a small performance impact. 842 843 If in doubt, say N here. 844 845config PARAVIRT_CLOCK 846 bool 847 848config JAILHOUSE_GUEST 849 bool "Jailhouse non-root cell support" 850 depends on X86_64 && PCI 851 select X86_PM_TIMER 852 help 853 This option allows to run Linux as guest in a Jailhouse non-root 854 cell. You can leave this option disabled if you only want to start 855 Jailhouse and run Linux afterwards in the root cell. 856 857config ACRN_GUEST 858 bool "ACRN Guest support" 859 depends on X86_64 860 select X86_HV_CALLBACK_VECTOR 861 help 862 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 863 a flexible, lightweight reference open-source hypervisor, built with 864 real-time and safety-criticality in mind. It is built for embedded 865 IOT with small footprint and real-time features. More details can be 866 found in https://projectacrn.org/. 867 868config INTEL_TDX_GUEST 869 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 870 depends on X86_64 && CPU_SUP_INTEL 871 depends on X86_X2APIC 872 select ARCH_HAS_CC_PLATFORM 873 select X86_MEM_ENCRYPT 874 select X86_MCE 875 help 876 Support running as a guest under Intel TDX. Without this support, 877 the guest kernel can not boot or run under TDX. 878 TDX includes memory encryption and integrity capabilities 879 which protect the confidentiality and integrity of guest 880 memory contents and CPU state. TDX guests are protected from 881 some attacks from the VMM. 882 883endif # HYPERVISOR_GUEST 884 885source "arch/x86/Kconfig.cpu" 886 887config HPET_TIMER 888 def_bool X86_64 889 prompt "HPET Timer Support" if X86_32 890 help 891 Use the IA-PC HPET (High Precision Event Timer) to manage 892 time in preference to the PIT and RTC, if a HPET is 893 present. 894 HPET is the next generation timer replacing legacy 8254s. 895 The HPET provides a stable time base on SMP 896 systems, unlike the TSC, but it is more expensive to access, 897 as it is off-chip. The interface used is documented 898 in the HPET spec, revision 1. 899 900 You can safely choose Y here. However, HPET will only be 901 activated if the platform and the BIOS support this feature. 902 Otherwise the 8254 will be used for timing services. 903 904 Choose N to continue using the legacy 8254 timer. 905 906config HPET_EMULATE_RTC 907 def_bool y 908 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 909 910# Mark as expert because too many people got it wrong. 911# The code disables itself when not needed. 912config DMI 913 default y 914 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 915 bool "Enable DMI scanning" if EXPERT 916 help 917 Enabled scanning of DMI to identify machine quirks. Say Y 918 here unless you have verified that your setup is not 919 affected by entries in the DMI blacklist. Required by PNP 920 BIOS code. 921 922config GART_IOMMU 923 bool "Old AMD GART IOMMU support" 924 select DMA_OPS 925 select IOMMU_HELPER 926 select SWIOTLB 927 depends on X86_64 && PCI && AMD_NB 928 help 929 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 930 GART based hardware IOMMUs. 931 932 The GART supports full DMA access for devices with 32-bit access 933 limitations, on systems with more than 3 GB. This is usually needed 934 for USB, sound, many IDE/SATA chipsets and some other devices. 935 936 Newer systems typically have a modern AMD IOMMU, supported via 937 the CONFIG_AMD_IOMMU=y config option. 938 939 In normal configurations this driver is only active when needed: 940 there's more than 3 GB of memory and the system contains a 941 32-bit limited device. 942 943 If unsure, say Y. 944 945config BOOT_VESA_SUPPORT 946 bool 947 help 948 If true, at least one selected framebuffer driver can take advantage 949 of VESA video modes set at an early boot stage via the vga= parameter. 950 951config MAXSMP 952 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 953 depends on X86_64 && SMP && DEBUG_KERNEL 954 select CPUMASK_OFFSTACK 955 help 956 Enable maximum number of CPUS and NUMA Nodes for this architecture. 957 If unsure, say N. 958 959# 960# The maximum number of CPUs supported: 961# 962# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 963# and which can be configured interactively in the 964# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 965# 966# The ranges are different on 32-bit and 64-bit kernels, depending on 967# hardware capabilities and scalability features of the kernel. 968# 969# ( If MAXSMP is enabled we just use the highest possible value and disable 970# interactive configuration. ) 971# 972 973config NR_CPUS_RANGE_BEGIN 974 int 975 default NR_CPUS_RANGE_END if MAXSMP 976 default 1 if !SMP 977 default 2 978 979config NR_CPUS_RANGE_END 980 int 981 depends on X86_32 982 default 64 if SMP && X86_BIGSMP 983 default 8 if SMP && !X86_BIGSMP 984 default 1 if !SMP 985 986config NR_CPUS_RANGE_END 987 int 988 depends on X86_64 989 default 8192 if SMP && CPUMASK_OFFSTACK 990 default 512 if SMP && !CPUMASK_OFFSTACK 991 default 1 if !SMP 992 993config NR_CPUS_DEFAULT 994 int 995 depends on X86_32 996 default 32 if X86_BIGSMP 997 default 8 if SMP 998 default 1 if !SMP 999 1000config NR_CPUS_DEFAULT 1001 int 1002 depends on X86_64 1003 default 8192 if MAXSMP 1004 default 64 if SMP 1005 default 1 if !SMP 1006 1007config NR_CPUS 1008 int "Maximum number of CPUs" if SMP && !MAXSMP 1009 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1010 default NR_CPUS_DEFAULT 1011 help 1012 This allows you to specify the maximum number of CPUs which this 1013 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1014 supported value is 8192, otherwise the maximum value is 512. The 1015 minimum value which makes sense is 2. 1016 1017 This is purely to save memory: each supported CPU adds about 8KB 1018 to the kernel image. 1019 1020config SCHED_CLUSTER 1021 bool "Cluster scheduler support" 1022 depends on SMP 1023 default y 1024 help 1025 Cluster scheduler support improves the CPU scheduler's decision 1026 making when dealing with machines that have clusters of CPUs. 1027 Cluster usually means a couple of CPUs which are placed closely 1028 by sharing mid-level caches, last-level cache tags or internal 1029 busses. 1030 1031config SCHED_SMT 1032 def_bool y if SMP 1033 1034config SCHED_MC 1035 def_bool y 1036 prompt "Multi-core scheduler support" 1037 depends on SMP 1038 help 1039 Multi-core scheduler support improves the CPU scheduler's decision 1040 making when dealing with multi-core CPU chips at a cost of slightly 1041 increased overhead in some places. If unsure say N here. 1042 1043config SCHED_MC_PRIO 1044 bool "CPU core priorities scheduler support" 1045 depends on SCHED_MC && CPU_SUP_INTEL 1046 select X86_INTEL_PSTATE 1047 select CPU_FREQ 1048 default y 1049 help 1050 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1051 core ordering determined at manufacturing time, which allows 1052 certain cores to reach higher turbo frequencies (when running 1053 single threaded workloads) than others. 1054 1055 Enabling this kernel feature teaches the scheduler about 1056 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1057 scheduler's CPU selection logic accordingly, so that higher 1058 overall system performance can be achieved. 1059 1060 This feature will have no effect on CPUs without this feature. 1061 1062 If unsure say Y here. 1063 1064config UP_LATE_INIT 1065 def_bool y 1066 depends on !SMP && X86_LOCAL_APIC 1067 1068config X86_UP_APIC 1069 bool "Local APIC support on uniprocessors" if !PCI_MSI 1070 default PCI_MSI 1071 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1072 help 1073 A local APIC (Advanced Programmable Interrupt Controller) is an 1074 integrated interrupt controller in the CPU. If you have a single-CPU 1075 system which has a processor with a local APIC, you can say Y here to 1076 enable and use it. If you say Y here even though your machine doesn't 1077 have a local APIC, then the kernel will still run with no slowdown at 1078 all. The local APIC supports CPU-generated self-interrupts (timer, 1079 performance counters), and the NMI watchdog which detects hard 1080 lockups. 1081 1082config X86_UP_IOAPIC 1083 bool "IO-APIC support on uniprocessors" 1084 depends on X86_UP_APIC 1085 help 1086 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1087 SMP-capable replacement for PC-style interrupt controllers. Most 1088 SMP systems and many recent uniprocessor systems have one. 1089 1090 If you have a single-CPU system with an IO-APIC, you can say Y here 1091 to use it. If you say Y here even though your machine doesn't have 1092 an IO-APIC, then the kernel will still run with no slowdown at all. 1093 1094config X86_LOCAL_APIC 1095 def_bool y 1096 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1097 select IRQ_DOMAIN_HIERARCHY 1098 select PCI_MSI_IRQ_DOMAIN if PCI_MSI 1099 1100config X86_IO_APIC 1101 def_bool y 1102 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1103 1104config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1105 bool "Reroute for broken boot IRQs" 1106 depends on X86_IO_APIC 1107 help 1108 This option enables a workaround that fixes a source of 1109 spurious interrupts. This is recommended when threaded 1110 interrupt handling is used on systems where the generation of 1111 superfluous "boot interrupts" cannot be disabled. 1112 1113 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1114 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1115 kernel does during interrupt handling). On chipsets where this 1116 boot IRQ generation cannot be disabled, this workaround keeps 1117 the original IRQ line masked so that only the equivalent "boot 1118 IRQ" is delivered to the CPUs. The workaround also tells the 1119 kernel to set up the IRQ handler on the boot IRQ line. In this 1120 way only one interrupt is delivered to the kernel. Otherwise 1121 the spurious second interrupt may cause the kernel to bring 1122 down (vital) interrupt lines. 1123 1124 Only affects "broken" chipsets. Interrupt sharing may be 1125 increased on these systems. 1126 1127config X86_MCE 1128 bool "Machine Check / overheating reporting" 1129 select GENERIC_ALLOCATOR 1130 default y 1131 help 1132 Machine Check support allows the processor to notify the 1133 kernel if it detects a problem (e.g. overheating, data corruption). 1134 The action the kernel takes depends on the severity of the problem, 1135 ranging from warning messages to halting the machine. 1136 1137config X86_MCELOG_LEGACY 1138 bool "Support for deprecated /dev/mcelog character device" 1139 depends on X86_MCE 1140 help 1141 Enable support for /dev/mcelog which is needed by the old mcelog 1142 userspace logging daemon. Consider switching to the new generation 1143 rasdaemon solution. 1144 1145config X86_MCE_INTEL 1146 def_bool y 1147 prompt "Intel MCE features" 1148 depends on X86_MCE && X86_LOCAL_APIC 1149 help 1150 Additional support for intel specific MCE features such as 1151 the thermal monitor. 1152 1153config X86_MCE_AMD 1154 def_bool y 1155 prompt "AMD MCE features" 1156 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1157 help 1158 Additional support for AMD specific MCE features such as 1159 the DRAM Error Threshold. 1160 1161config X86_ANCIENT_MCE 1162 bool "Support for old Pentium 5 / WinChip machine checks" 1163 depends on X86_32 && X86_MCE 1164 help 1165 Include support for machine check handling on old Pentium 5 or WinChip 1166 systems. These typically need to be enabled explicitly on the command 1167 line. 1168 1169config X86_MCE_THRESHOLD 1170 depends on X86_MCE_AMD || X86_MCE_INTEL 1171 def_bool y 1172 1173config X86_MCE_INJECT 1174 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1175 tristate "Machine check injector support" 1176 help 1177 Provide support for injecting machine checks for testing purposes. 1178 If you don't know what a machine check is and you don't do kernel 1179 QA it is safe to say n. 1180 1181source "arch/x86/events/Kconfig" 1182 1183config X86_LEGACY_VM86 1184 bool "Legacy VM86 support" 1185 depends on X86_32 1186 help 1187 This option allows user programs to put the CPU into V8086 1188 mode, which is an 80286-era approximation of 16-bit real mode. 1189 1190 Some very old versions of X and/or vbetool require this option 1191 for user mode setting. Similarly, DOSEMU will use it if 1192 available to accelerate real mode DOS programs. However, any 1193 recent version of DOSEMU, X, or vbetool should be fully 1194 functional even without kernel VM86 support, as they will all 1195 fall back to software emulation. Nevertheless, if you are using 1196 a 16-bit DOS program where 16-bit performance matters, vm86 1197 mode might be faster than emulation and you might want to 1198 enable this option. 1199 1200 Note that any app that works on a 64-bit kernel is unlikely to 1201 need this option, as 64-bit kernels don't, and can't, support 1202 V8086 mode. This option is also unrelated to 16-bit protected 1203 mode and is not needed to run most 16-bit programs under Wine. 1204 1205 Enabling this option increases the complexity of the kernel 1206 and slows down exception handling a tiny bit. 1207 1208 If unsure, say N here. 1209 1210config VM86 1211 bool 1212 default X86_LEGACY_VM86 1213 1214config X86_16BIT 1215 bool "Enable support for 16-bit segments" if EXPERT 1216 default y 1217 depends on MODIFY_LDT_SYSCALL 1218 help 1219 This option is required by programs like Wine to run 16-bit 1220 protected mode legacy code on x86 processors. Disabling 1221 this option saves about 300 bytes on i386, or around 6K text 1222 plus 16K runtime memory on x86-64, 1223 1224config X86_ESPFIX32 1225 def_bool y 1226 depends on X86_16BIT && X86_32 1227 1228config X86_ESPFIX64 1229 def_bool y 1230 depends on X86_16BIT && X86_64 1231 1232config X86_VSYSCALL_EMULATION 1233 bool "Enable vsyscall emulation" if EXPERT 1234 default y 1235 depends on X86_64 1236 help 1237 This enables emulation of the legacy vsyscall page. Disabling 1238 it is roughly equivalent to booting with vsyscall=none, except 1239 that it will also disable the helpful warning if a program 1240 tries to use a vsyscall. With this option set to N, offending 1241 programs will just segfault, citing addresses of the form 1242 0xffffffffff600?00. 1243 1244 This option is required by many programs built before 2013, and 1245 care should be used even with newer programs if set to N. 1246 1247 Disabling this option saves about 7K of kernel size and 1248 possibly 4K of additional runtime pagetable memory. 1249 1250config X86_IOPL_IOPERM 1251 bool "IOPERM and IOPL Emulation" 1252 default y 1253 help 1254 This enables the ioperm() and iopl() syscalls which are necessary 1255 for legacy applications. 1256 1257 Legacy IOPL support is an overbroad mechanism which allows user 1258 space aside of accessing all 65536 I/O ports also to disable 1259 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1260 capabilities and permission from potentially active security 1261 modules. 1262 1263 The emulation restricts the functionality of the syscall to 1264 only allowing the full range I/O port access, but prevents the 1265 ability to disable interrupts from user space which would be 1266 granted if the hardware IOPL mechanism would be used. 1267 1268config TOSHIBA 1269 tristate "Toshiba Laptop support" 1270 depends on X86_32 1271 help 1272 This adds a driver to safely access the System Management Mode of 1273 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1274 not work on models with a Phoenix BIOS. The System Management Mode 1275 is used to set the BIOS and power saving options on Toshiba portables. 1276 1277 For information on utilities to make use of this driver see the 1278 Toshiba Linux utilities web site at: 1279 <http://www.buzzard.org.uk/toshiba/>. 1280 1281 Say Y if you intend to run this kernel on a Toshiba portable. 1282 Say N otherwise. 1283 1284config X86_REBOOTFIXUPS 1285 bool "Enable X86 board specific fixups for reboot" 1286 depends on X86_32 1287 help 1288 This enables chipset and/or board specific fixups to be done 1289 in order to get reboot to work correctly. This is only needed on 1290 some combinations of hardware and BIOS. The symptom, for which 1291 this config is intended, is when reboot ends with a stalled/hung 1292 system. 1293 1294 Currently, the only fixup is for the Geode machines using 1295 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1296 1297 Say Y if you want to enable the fixup. Currently, it's safe to 1298 enable this option even if you don't need it. 1299 Say N otherwise. 1300 1301config MICROCODE 1302 bool "CPU microcode loading support" 1303 default y 1304 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1305 help 1306 If you say Y here, you will be able to update the microcode on 1307 Intel and AMD processors. The Intel support is for the IA32 family, 1308 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1309 AMD support is for families 0x10 and later. You will obviously need 1310 the actual microcode binary data itself which is not shipped with 1311 the Linux kernel. 1312 1313 The preferred method to load microcode from a detached initrd is described 1314 in Documentation/x86/microcode.rst. For that you need to enable 1315 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1316 initrd for microcode blobs. 1317 1318 In addition, you can build the microcode into the kernel. For that you 1319 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1320 config option. 1321 1322config MICROCODE_INTEL 1323 bool "Intel microcode loading support" 1324 depends on CPU_SUP_INTEL && MICROCODE 1325 default MICROCODE 1326 help 1327 This options enables microcode patch loading support for Intel 1328 processors. 1329 1330 For the current Intel microcode data package go to 1331 <https://downloadcenter.intel.com> and search for 1332 'Linux Processor Microcode Data File'. 1333 1334config MICROCODE_AMD 1335 bool "AMD microcode loading support" 1336 depends on CPU_SUP_AMD && MICROCODE 1337 help 1338 If you select this option, microcode patch loading support for AMD 1339 processors will be enabled. 1340 1341config MICROCODE_LATE_LOADING 1342 bool "Late microcode loading (DANGEROUS)" 1343 default n 1344 depends on MICROCODE 1345 help 1346 Loading microcode late, when the system is up and executing instructions 1347 is a tricky business and should be avoided if possible. Just the sequence 1348 of synchronizing all cores and SMT threads is one fragile dance which does 1349 not guarantee that cores might not softlock after the loading. Therefore, 1350 use this at your own risk. Late loading taints the kernel too. 1351 1352config X86_MSR 1353 tristate "/dev/cpu/*/msr - Model-specific register support" 1354 help 1355 This device gives privileged processes access to the x86 1356 Model-Specific Registers (MSRs). It is a character device with 1357 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1358 MSR accesses are directed to a specific CPU on multi-processor 1359 systems. 1360 1361config X86_CPUID 1362 tristate "/dev/cpu/*/cpuid - CPU information support" 1363 help 1364 This device gives processes access to the x86 CPUID instruction to 1365 be executed on a specific processor. It is a character device 1366 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1367 /dev/cpu/31/cpuid. 1368 1369choice 1370 prompt "High Memory Support" 1371 default HIGHMEM4G 1372 depends on X86_32 1373 1374config NOHIGHMEM 1375 bool "off" 1376 help 1377 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1378 However, the address space of 32-bit x86 processors is only 4 1379 Gigabytes large. That means that, if you have a large amount of 1380 physical memory, not all of it can be "permanently mapped" by the 1381 kernel. The physical memory that's not permanently mapped is called 1382 "high memory". 1383 1384 If you are compiling a kernel which will never run on a machine with 1385 more than 1 Gigabyte total physical RAM, answer "off" here (default 1386 choice and suitable for most users). This will result in a "3GB/1GB" 1387 split: 3GB are mapped so that each process sees a 3GB virtual memory 1388 space and the remaining part of the 4GB virtual memory space is used 1389 by the kernel to permanently map as much physical memory as 1390 possible. 1391 1392 If the machine has between 1 and 4 Gigabytes physical RAM, then 1393 answer "4GB" here. 1394 1395 If more than 4 Gigabytes is used then answer "64GB" here. This 1396 selection turns Intel PAE (Physical Address Extension) mode on. 1397 PAE implements 3-level paging on IA32 processors. PAE is fully 1398 supported by Linux, PAE mode is implemented on all recent Intel 1399 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1400 then the kernel will not boot on CPUs that don't support PAE! 1401 1402 The actual amount of total physical memory will either be 1403 auto detected or can be forced by using a kernel command line option 1404 such as "mem=256M". (Try "man bootparam" or see the documentation of 1405 your boot loader (lilo or loadlin) about how to pass options to the 1406 kernel at boot time.) 1407 1408 If unsure, say "off". 1409 1410config HIGHMEM4G 1411 bool "4GB" 1412 help 1413 Select this if you have a 32-bit processor and between 1 and 4 1414 gigabytes of physical RAM. 1415 1416config HIGHMEM64G 1417 bool "64GB" 1418 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1419 select X86_PAE 1420 help 1421 Select this if you have a 32-bit processor and more than 4 1422 gigabytes of physical RAM. 1423 1424endchoice 1425 1426choice 1427 prompt "Memory split" if EXPERT 1428 default VMSPLIT_3G 1429 depends on X86_32 1430 help 1431 Select the desired split between kernel and user memory. 1432 1433 If the address range available to the kernel is less than the 1434 physical memory installed, the remaining memory will be available 1435 as "high memory". Accessing high memory is a little more costly 1436 than low memory, as it needs to be mapped into the kernel first. 1437 Note that increasing the kernel address space limits the range 1438 available to user programs, making the address space there 1439 tighter. Selecting anything other than the default 3G/1G split 1440 will also likely make your kernel incompatible with binary-only 1441 kernel modules. 1442 1443 If you are not absolutely sure what you are doing, leave this 1444 option alone! 1445 1446 config VMSPLIT_3G 1447 bool "3G/1G user/kernel split" 1448 config VMSPLIT_3G_OPT 1449 depends on !X86_PAE 1450 bool "3G/1G user/kernel split (for full 1G low memory)" 1451 config VMSPLIT_2G 1452 bool "2G/2G user/kernel split" 1453 config VMSPLIT_2G_OPT 1454 depends on !X86_PAE 1455 bool "2G/2G user/kernel split (for full 2G low memory)" 1456 config VMSPLIT_1G 1457 bool "1G/3G user/kernel split" 1458endchoice 1459 1460config PAGE_OFFSET 1461 hex 1462 default 0xB0000000 if VMSPLIT_3G_OPT 1463 default 0x80000000 if VMSPLIT_2G 1464 default 0x78000000 if VMSPLIT_2G_OPT 1465 default 0x40000000 if VMSPLIT_1G 1466 default 0xC0000000 1467 depends on X86_32 1468 1469config HIGHMEM 1470 def_bool y 1471 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1472 1473config X86_PAE 1474 bool "PAE (Physical Address Extension) Support" 1475 depends on X86_32 && !HIGHMEM4G 1476 select PHYS_ADDR_T_64BIT 1477 select SWIOTLB 1478 help 1479 PAE is required for NX support, and furthermore enables 1480 larger swapspace support for non-overcommit purposes. It 1481 has the cost of more pagetable lookup overhead, and also 1482 consumes more pagetable space per process. 1483 1484config X86_5LEVEL 1485 bool "Enable 5-level page tables support" 1486 default y 1487 select DYNAMIC_MEMORY_LAYOUT 1488 select SPARSEMEM_VMEMMAP 1489 depends on X86_64 1490 help 1491 5-level paging enables access to larger address space: 1492 upto 128 PiB of virtual address space and 4 PiB of 1493 physical address space. 1494 1495 It will be supported by future Intel CPUs. 1496 1497 A kernel with the option enabled can be booted on machines that 1498 support 4- or 5-level paging. 1499 1500 See Documentation/x86/x86_64/5level-paging.rst for more 1501 information. 1502 1503 Say N if unsure. 1504 1505config X86_DIRECT_GBPAGES 1506 def_bool y 1507 depends on X86_64 1508 help 1509 Certain kernel features effectively disable kernel 1510 linear 1 GB mappings (even if the CPU otherwise 1511 supports them), so don't confuse the user by printing 1512 that we have them enabled. 1513 1514config X86_CPA_STATISTICS 1515 bool "Enable statistic for Change Page Attribute" 1516 depends on DEBUG_FS 1517 help 1518 Expose statistics about the Change Page Attribute mechanism, which 1519 helps to determine the effectiveness of preserving large and huge 1520 page mappings when mapping protections are changed. 1521 1522config X86_MEM_ENCRYPT 1523 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1524 select DYNAMIC_PHYSICAL_MASK 1525 def_bool n 1526 1527config AMD_MEM_ENCRYPT 1528 bool "AMD Secure Memory Encryption (SME) support" 1529 depends on X86_64 && CPU_SUP_AMD 1530 select DMA_COHERENT_POOL 1531 select ARCH_USE_MEMREMAP_PROT 1532 select INSTRUCTION_DECODER 1533 select ARCH_HAS_CC_PLATFORM 1534 select X86_MEM_ENCRYPT 1535 help 1536 Say yes to enable support for the encryption of system memory. 1537 This requires an AMD processor that supports Secure Memory 1538 Encryption (SME). 1539 1540config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1541 bool "Activate AMD Secure Memory Encryption (SME) by default" 1542 depends on AMD_MEM_ENCRYPT 1543 help 1544 Say yes to have system memory encrypted by default if running on 1545 an AMD processor that supports Secure Memory Encryption (SME). 1546 1547 If set to Y, then the encryption of system memory can be 1548 deactivated with the mem_encrypt=off command line option. 1549 1550 If set to N, then the encryption of system memory can be 1551 activated with the mem_encrypt=on command line option. 1552 1553# Common NUMA Features 1554config NUMA 1555 bool "NUMA Memory Allocation and Scheduler Support" 1556 depends on SMP 1557 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1558 default y if X86_BIGSMP 1559 select USE_PERCPU_NUMA_NODE_ID 1560 help 1561 Enable NUMA (Non-Uniform Memory Access) support. 1562 1563 The kernel will try to allocate memory used by a CPU on the 1564 local memory controller of the CPU and add some more 1565 NUMA awareness to the kernel. 1566 1567 For 64-bit this is recommended if the system is Intel Core i7 1568 (or later), AMD Opteron, or EM64T NUMA. 1569 1570 For 32-bit this is only needed if you boot a 32-bit 1571 kernel on a 64-bit NUMA platform. 1572 1573 Otherwise, you should say N. 1574 1575config AMD_NUMA 1576 def_bool y 1577 prompt "Old style AMD Opteron NUMA detection" 1578 depends on X86_64 && NUMA && PCI 1579 help 1580 Enable AMD NUMA node topology detection. You should say Y here if 1581 you have a multi processor AMD system. This uses an old method to 1582 read the NUMA configuration directly from the builtin Northbridge 1583 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1584 which also takes priority if both are compiled in. 1585 1586config X86_64_ACPI_NUMA 1587 def_bool y 1588 prompt "ACPI NUMA detection" 1589 depends on X86_64 && NUMA && ACPI && PCI 1590 select ACPI_NUMA 1591 help 1592 Enable ACPI SRAT based node topology detection. 1593 1594config NUMA_EMU 1595 bool "NUMA emulation" 1596 depends on NUMA 1597 help 1598 Enable NUMA emulation. A flat machine will be split 1599 into virtual nodes when booted with "numa=fake=N", where N is the 1600 number of nodes. This is only useful for debugging. 1601 1602config NODES_SHIFT 1603 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1604 range 1 10 1605 default "10" if MAXSMP 1606 default "6" if X86_64 1607 default "3" 1608 depends on NUMA 1609 help 1610 Specify the maximum number of NUMA Nodes available on the target 1611 system. Increases memory reserved to accommodate various tables. 1612 1613config ARCH_FLATMEM_ENABLE 1614 def_bool y 1615 depends on X86_32 && !NUMA 1616 1617config ARCH_SPARSEMEM_ENABLE 1618 def_bool y 1619 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1620 select SPARSEMEM_STATIC if X86_32 1621 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1622 1623config ARCH_SPARSEMEM_DEFAULT 1624 def_bool X86_64 || (NUMA && X86_32) 1625 1626config ARCH_SELECT_MEMORY_MODEL 1627 def_bool y 1628 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1629 1630config ARCH_MEMORY_PROBE 1631 bool "Enable sysfs memory/probe interface" 1632 depends on MEMORY_HOTPLUG 1633 help 1634 This option enables a sysfs memory/probe interface for testing. 1635 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1636 If you are unsure how to answer this question, answer N. 1637 1638config ARCH_PROC_KCORE_TEXT 1639 def_bool y 1640 depends on X86_64 && PROC_KCORE 1641 1642config ILLEGAL_POINTER_VALUE 1643 hex 1644 default 0 if X86_32 1645 default 0xdead000000000000 if X86_64 1646 1647config X86_PMEM_LEGACY_DEVICE 1648 bool 1649 1650config X86_PMEM_LEGACY 1651 tristate "Support non-standard NVDIMMs and ADR protected memory" 1652 depends on PHYS_ADDR_T_64BIT 1653 depends on BLK_DEV 1654 select X86_PMEM_LEGACY_DEVICE 1655 select NUMA_KEEP_MEMINFO if NUMA 1656 select LIBNVDIMM 1657 help 1658 Treat memory marked using the non-standard e820 type of 12 as used 1659 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1660 The kernel will offer these regions to the 'pmem' driver so 1661 they can be used for persistent storage. 1662 1663 Say Y if unsure. 1664 1665config HIGHPTE 1666 bool "Allocate 3rd-level pagetables from highmem" 1667 depends on HIGHMEM 1668 help 1669 The VM uses one page table entry for each page of physical memory. 1670 For systems with a lot of RAM, this can be wasteful of precious 1671 low memory. Setting this option will put user-space page table 1672 entries in high memory. 1673 1674config X86_CHECK_BIOS_CORRUPTION 1675 bool "Check for low memory corruption" 1676 help 1677 Periodically check for memory corruption in low memory, which 1678 is suspected to be caused by BIOS. Even when enabled in the 1679 configuration, it is disabled at runtime. Enable it by 1680 setting "memory_corruption_check=1" on the kernel command 1681 line. By default it scans the low 64k of memory every 60 1682 seconds; see the memory_corruption_check_size and 1683 memory_corruption_check_period parameters in 1684 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1685 1686 When enabled with the default parameters, this option has 1687 almost no overhead, as it reserves a relatively small amount 1688 of memory and scans it infrequently. It both detects corruption 1689 and prevents it from affecting the running system. 1690 1691 It is, however, intended as a diagnostic tool; if repeatable 1692 BIOS-originated corruption always affects the same memory, 1693 you can use memmap= to prevent the kernel from using that 1694 memory. 1695 1696config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1697 bool "Set the default setting of memory_corruption_check" 1698 depends on X86_CHECK_BIOS_CORRUPTION 1699 default y 1700 help 1701 Set whether the default state of memory_corruption_check is 1702 on or off. 1703 1704config MATH_EMULATION 1705 bool 1706 depends on MODIFY_LDT_SYSCALL 1707 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1708 help 1709 Linux can emulate a math coprocessor (used for floating point 1710 operations) if you don't have one. 486DX and Pentium processors have 1711 a math coprocessor built in, 486SX and 386 do not, unless you added 1712 a 487DX or 387, respectively. (The messages during boot time can 1713 give you some hints here ["man dmesg"].) Everyone needs either a 1714 coprocessor or this emulation. 1715 1716 If you don't have a math coprocessor, you need to say Y here; if you 1717 say Y here even though you have a coprocessor, the coprocessor will 1718 be used nevertheless. (This behavior can be changed with the kernel 1719 command line option "no387", which comes handy if your coprocessor 1720 is broken. Try "man bootparam" or see the documentation of your boot 1721 loader (lilo or loadlin) about how to pass options to the kernel at 1722 boot time.) This means that it is a good idea to say Y here if you 1723 intend to use this kernel on different machines. 1724 1725 More information about the internals of the Linux math coprocessor 1726 emulation can be found in <file:arch/x86/math-emu/README>. 1727 1728 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1729 kernel, it won't hurt. 1730 1731config MTRR 1732 def_bool y 1733 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1734 help 1735 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1736 the Memory Type Range Registers (MTRRs) may be used to control 1737 processor access to memory ranges. This is most useful if you have 1738 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1739 allows bus write transfers to be combined into a larger transfer 1740 before bursting over the PCI/AGP bus. This can increase performance 1741 of image write operations 2.5 times or more. Saying Y here creates a 1742 /proc/mtrr file which may be used to manipulate your processor's 1743 MTRRs. Typically the X server should use this. 1744 1745 This code has a reasonably generic interface so that similar 1746 control registers on other processors can be easily supported 1747 as well: 1748 1749 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1750 Registers (ARRs) which provide a similar functionality to MTRRs. For 1751 these, the ARRs are used to emulate the MTRRs. 1752 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1753 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1754 write-combining. All of these processors are supported by this code 1755 and it makes sense to say Y here if you have one of them. 1756 1757 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1758 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1759 can lead to all sorts of problems, so it's good to say Y here. 1760 1761 You can safely say Y even if your machine doesn't have MTRRs, you'll 1762 just add about 9 KB to your kernel. 1763 1764 See <file:Documentation/x86/mtrr.rst> for more information. 1765 1766config MTRR_SANITIZER 1767 def_bool y 1768 prompt "MTRR cleanup support" 1769 depends on MTRR 1770 help 1771 Convert MTRR layout from continuous to discrete, so X drivers can 1772 add writeback entries. 1773 1774 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1775 The largest mtrr entry size for a continuous block can be set with 1776 mtrr_chunk_size. 1777 1778 If unsure, say Y. 1779 1780config MTRR_SANITIZER_ENABLE_DEFAULT 1781 int "MTRR cleanup enable value (0-1)" 1782 range 0 1 1783 default "0" 1784 depends on MTRR_SANITIZER 1785 help 1786 Enable mtrr cleanup default value 1787 1788config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1789 int "MTRR cleanup spare reg num (0-7)" 1790 range 0 7 1791 default "1" 1792 depends on MTRR_SANITIZER 1793 help 1794 mtrr cleanup spare entries default, it can be changed via 1795 mtrr_spare_reg_nr=N on the kernel command line. 1796 1797config X86_PAT 1798 def_bool y 1799 prompt "x86 PAT support" if EXPERT 1800 depends on MTRR 1801 help 1802 Use PAT attributes to setup page level cache control. 1803 1804 PATs are the modern equivalents of MTRRs and are much more 1805 flexible than MTRRs. 1806 1807 Say N here if you see bootup problems (boot crash, boot hang, 1808 spontaneous reboots) or a non-working video driver. 1809 1810 If unsure, say Y. 1811 1812config ARCH_USES_PG_UNCACHED 1813 def_bool y 1814 depends on X86_PAT 1815 1816config X86_UMIP 1817 def_bool y 1818 prompt "User Mode Instruction Prevention" if EXPERT 1819 help 1820 User Mode Instruction Prevention (UMIP) is a security feature in 1821 some x86 processors. If enabled, a general protection fault is 1822 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1823 executed in user mode. These instructions unnecessarily expose 1824 information about the hardware state. 1825 1826 The vast majority of applications do not use these instructions. 1827 For the very few that do, software emulation is provided in 1828 specific cases in protected and virtual-8086 modes. Emulated 1829 results are dummy. 1830 1831config CC_HAS_IBT 1832 # GCC >= 9 and binutils >= 2.29 1833 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1834 # Clang/LLVM >= 14 1835 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1836 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1837 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1838 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1839 $(as-instr,endbr64) 1840 1841config X86_KERNEL_IBT 1842 prompt "Indirect Branch Tracking" 1843 bool 1844 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1845 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1846 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1847 select OBJTOOL 1848 help 1849 Build the kernel with support for Indirect Branch Tracking, a 1850 hardware support course-grain forward-edge Control Flow Integrity 1851 protection. It enforces that all indirect calls must land on 1852 an ENDBR instruction, as such, the compiler will instrument the 1853 code with them to make this happen. 1854 1855 In addition to building the kernel with IBT, seal all functions that 1856 are not indirect call targets, avoiding them ever becoming one. 1857 1858 This requires LTO like objtool runs and will slow down the build. It 1859 does significantly reduce the number of ENDBR instructions in the 1860 kernel image. 1861 1862config X86_INTEL_MEMORY_PROTECTION_KEYS 1863 prompt "Memory Protection Keys" 1864 def_bool y 1865 # Note: only available in 64-bit mode 1866 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1867 select ARCH_USES_HIGH_VMA_FLAGS 1868 select ARCH_HAS_PKEYS 1869 help 1870 Memory Protection Keys provides a mechanism for enforcing 1871 page-based protections, but without requiring modification of the 1872 page tables when an application changes protection domains. 1873 1874 For details, see Documentation/core-api/protection-keys.rst 1875 1876 If unsure, say y. 1877 1878choice 1879 prompt "TSX enable mode" 1880 depends on CPU_SUP_INTEL 1881 default X86_INTEL_TSX_MODE_OFF 1882 help 1883 Intel's TSX (Transactional Synchronization Extensions) feature 1884 allows to optimize locking protocols through lock elision which 1885 can lead to a noticeable performance boost. 1886 1887 On the other hand it has been shown that TSX can be exploited 1888 to form side channel attacks (e.g. TAA) and chances are there 1889 will be more of those attacks discovered in the future. 1890 1891 Therefore TSX is not enabled by default (aka tsx=off). An admin 1892 might override this decision by tsx=on the command line parameter. 1893 Even with TSX enabled, the kernel will attempt to enable the best 1894 possible TAA mitigation setting depending on the microcode available 1895 for the particular machine. 1896 1897 This option allows to set the default tsx mode between tsx=on, =off 1898 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1899 details. 1900 1901 Say off if not sure, auto if TSX is in use but it should be used on safe 1902 platforms or on if TSX is in use and the security aspect of tsx is not 1903 relevant. 1904 1905config X86_INTEL_TSX_MODE_OFF 1906 bool "off" 1907 help 1908 TSX is disabled if possible - equals to tsx=off command line parameter. 1909 1910config X86_INTEL_TSX_MODE_ON 1911 bool "on" 1912 help 1913 TSX is always enabled on TSX capable HW - equals the tsx=on command 1914 line parameter. 1915 1916config X86_INTEL_TSX_MODE_AUTO 1917 bool "auto" 1918 help 1919 TSX is enabled on TSX capable HW that is believed to be safe against 1920 side channel attacks- equals the tsx=auto command line parameter. 1921endchoice 1922 1923config X86_SGX 1924 bool "Software Guard eXtensions (SGX)" 1925 depends on X86_64 && CPU_SUP_INTEL 1926 depends on CRYPTO=y 1927 depends on CRYPTO_SHA256=y 1928 select SRCU 1929 select MMU_NOTIFIER 1930 select NUMA_KEEP_MEMINFO if NUMA 1931 select XARRAY_MULTI 1932 help 1933 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1934 that can be used by applications to set aside private regions of code 1935 and data, referred to as enclaves. An enclave's private memory can 1936 only be accessed by code running within the enclave. Accesses from 1937 outside the enclave, including other enclaves, are disallowed by 1938 hardware. 1939 1940 If unsure, say N. 1941 1942config EFI 1943 bool "EFI runtime service support" 1944 depends on ACPI 1945 select UCS2_STRING 1946 select EFI_RUNTIME_WRAPPERS 1947 select ARCH_USE_MEMREMAP_PROT 1948 help 1949 This enables the kernel to use EFI runtime services that are 1950 available (such as the EFI variable services). 1951 1952 This option is only useful on systems that have EFI firmware. 1953 In addition, you should use the latest ELILO loader available 1954 at <http://elilo.sourceforge.net> in order to take advantage 1955 of EFI runtime services. However, even with this option, the 1956 resultant kernel should continue to boot on existing non-EFI 1957 platforms. 1958 1959config EFI_STUB 1960 bool "EFI stub support" 1961 depends on EFI 1962 depends on $(cc-option,-mabi=ms) || X86_32 1963 select RELOCATABLE 1964 help 1965 This kernel feature allows a bzImage to be loaded directly 1966 by EFI firmware without the use of a bootloader. 1967 1968 See Documentation/admin-guide/efi-stub.rst for more information. 1969 1970config EFI_MIXED 1971 bool "EFI mixed-mode support" 1972 depends on EFI_STUB && X86_64 1973 help 1974 Enabling this feature allows a 64-bit kernel to be booted 1975 on a 32-bit firmware, provided that your CPU supports 64-bit 1976 mode. 1977 1978 Note that it is not possible to boot a mixed-mode enabled 1979 kernel via the EFI boot stub - a bootloader that supports 1980 the EFI handover protocol must be used. 1981 1982 If unsure, say N. 1983 1984source "kernel/Kconfig.hz" 1985 1986config KEXEC 1987 bool "kexec system call" 1988 select KEXEC_CORE 1989 help 1990 kexec is a system call that implements the ability to shutdown your 1991 current kernel, and to start another kernel. It is like a reboot 1992 but it is independent of the system firmware. And like a reboot 1993 you can start any kernel with it, not just Linux. 1994 1995 The name comes from the similarity to the exec system call. 1996 1997 It is an ongoing process to be certain the hardware in a machine 1998 is properly shutdown, so do not be surprised if this code does not 1999 initially work for you. As of this writing the exact hardware 2000 interface is strongly in flux, so no good recommendation can be 2001 made. 2002 2003config KEXEC_FILE 2004 bool "kexec file based system call" 2005 select KEXEC_CORE 2006 select HAVE_IMA_KEXEC if IMA 2007 depends on X86_64 2008 depends on CRYPTO=y 2009 depends on CRYPTO_SHA256=y 2010 help 2011 This is new version of kexec system call. This system call is 2012 file based and takes file descriptors as system call argument 2013 for kernel and initramfs as opposed to list of segments as 2014 accepted by previous system call. 2015 2016config ARCH_HAS_KEXEC_PURGATORY 2017 def_bool KEXEC_FILE 2018 2019config KEXEC_SIG 2020 bool "Verify kernel signature during kexec_file_load() syscall" 2021 depends on KEXEC_FILE 2022 help 2023 2024 This option makes the kexec_file_load() syscall check for a valid 2025 signature of the kernel image. The image can still be loaded without 2026 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2027 there's a signature that we can check, then it must be valid. 2028 2029 In addition to this option, you need to enable signature 2030 verification for the corresponding kernel image type being 2031 loaded in order for this to work. 2032 2033config KEXEC_SIG_FORCE 2034 bool "Require a valid signature in kexec_file_load() syscall" 2035 depends on KEXEC_SIG 2036 help 2037 This option makes kernel signature verification mandatory for 2038 the kexec_file_load() syscall. 2039 2040config KEXEC_BZIMAGE_VERIFY_SIG 2041 bool "Enable bzImage signature verification support" 2042 depends on KEXEC_SIG 2043 depends on SIGNED_PE_FILE_VERIFICATION 2044 select SYSTEM_TRUSTED_KEYRING 2045 help 2046 Enable bzImage signature verification support. 2047 2048config CRASH_DUMP 2049 bool "kernel crash dumps" 2050 depends on X86_64 || (X86_32 && HIGHMEM) 2051 help 2052 Generate crash dump after being started by kexec. 2053 This should be normally only set in special crash dump kernels 2054 which are loaded in the main kernel with kexec-tools into 2055 a specially reserved region and then later executed after 2056 a crash by kdump/kexec. The crash dump kernel must be compiled 2057 to a memory address not used by the main kernel or BIOS using 2058 PHYSICAL_START, or it must be built as a relocatable image 2059 (CONFIG_RELOCATABLE=y). 2060 For more details see Documentation/admin-guide/kdump/kdump.rst 2061 2062config KEXEC_JUMP 2063 bool "kexec jump" 2064 depends on KEXEC && HIBERNATION 2065 help 2066 Jump between original kernel and kexeced kernel and invoke 2067 code in physical address mode via KEXEC 2068 2069config PHYSICAL_START 2070 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2071 default "0x1000000" 2072 help 2073 This gives the physical address where the kernel is loaded. 2074 2075 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2076 bzImage will decompress itself to above physical address and 2077 run from there. Otherwise, bzImage will run from the address where 2078 it has been loaded by the boot loader and will ignore above physical 2079 address. 2080 2081 In normal kdump cases one does not have to set/change this option 2082 as now bzImage can be compiled as a completely relocatable image 2083 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2084 address. This option is mainly useful for the folks who don't want 2085 to use a bzImage for capturing the crash dump and want to use a 2086 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2087 to be specifically compiled to run from a specific memory area 2088 (normally a reserved region) and this option comes handy. 2089 2090 So if you are using bzImage for capturing the crash dump, 2091 leave the value here unchanged to 0x1000000 and set 2092 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2093 for capturing the crash dump change this value to start of 2094 the reserved region. In other words, it can be set based on 2095 the "X" value as specified in the "crashkernel=YM@XM" 2096 command line boot parameter passed to the panic-ed 2097 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2098 for more details about crash dumps. 2099 2100 Usage of bzImage for capturing the crash dump is recommended as 2101 one does not have to build two kernels. Same kernel can be used 2102 as production kernel and capture kernel. Above option should have 2103 gone away after relocatable bzImage support is introduced. But it 2104 is present because there are users out there who continue to use 2105 vmlinux for dump capture. This option should go away down the 2106 line. 2107 2108 Don't change this unless you know what you are doing. 2109 2110config RELOCATABLE 2111 bool "Build a relocatable kernel" 2112 default y 2113 help 2114 This builds a kernel image that retains relocation information 2115 so it can be loaded someplace besides the default 1MB. 2116 The relocations tend to make the kernel binary about 10% larger, 2117 but are discarded at runtime. 2118 2119 One use is for the kexec on panic case where the recovery kernel 2120 must live at a different physical address than the primary 2121 kernel. 2122 2123 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2124 it has been loaded at and the compile time physical address 2125 (CONFIG_PHYSICAL_START) is used as the minimum location. 2126 2127config RANDOMIZE_BASE 2128 bool "Randomize the address of the kernel image (KASLR)" 2129 depends on RELOCATABLE 2130 default y 2131 help 2132 In support of Kernel Address Space Layout Randomization (KASLR), 2133 this randomizes the physical address at which the kernel image 2134 is decompressed and the virtual address where the kernel 2135 image is mapped, as a security feature that deters exploit 2136 attempts relying on knowledge of the location of kernel 2137 code internals. 2138 2139 On 64-bit, the kernel physical and virtual addresses are 2140 randomized separately. The physical address will be anywhere 2141 between 16MB and the top of physical memory (up to 64TB). The 2142 virtual address will be randomized from 16MB up to 1GB (9 bits 2143 of entropy). Note that this also reduces the memory space 2144 available to kernel modules from 1.5GB to 1GB. 2145 2146 On 32-bit, the kernel physical and virtual addresses are 2147 randomized together. They will be randomized from 16MB up to 2148 512MB (8 bits of entropy). 2149 2150 Entropy is generated using the RDRAND instruction if it is 2151 supported. If RDTSC is supported, its value is mixed into 2152 the entropy pool as well. If neither RDRAND nor RDTSC are 2153 supported, then entropy is read from the i8254 timer. The 2154 usable entropy is limited by the kernel being built using 2155 2GB addressing, and that PHYSICAL_ALIGN must be at a 2156 minimum of 2MB. As a result, only 10 bits of entropy are 2157 theoretically possible, but the implementations are further 2158 limited due to memory layouts. 2159 2160 If unsure, say Y. 2161 2162# Relocation on x86 needs some additional build support 2163config X86_NEED_RELOCS 2164 def_bool y 2165 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2166 2167config PHYSICAL_ALIGN 2168 hex "Alignment value to which kernel should be aligned" 2169 default "0x200000" 2170 range 0x2000 0x1000000 if X86_32 2171 range 0x200000 0x1000000 if X86_64 2172 help 2173 This value puts the alignment restrictions on physical address 2174 where kernel is loaded and run from. Kernel is compiled for an 2175 address which meets above alignment restriction. 2176 2177 If bootloader loads the kernel at a non-aligned address and 2178 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2179 address aligned to above value and run from there. 2180 2181 If bootloader loads the kernel at a non-aligned address and 2182 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2183 load address and decompress itself to the address it has been 2184 compiled for and run from there. The address for which kernel is 2185 compiled already meets above alignment restrictions. Hence the 2186 end result is that kernel runs from a physical address meeting 2187 above alignment restrictions. 2188 2189 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2190 this value must be a multiple of 0x200000. 2191 2192 Don't change this unless you know what you are doing. 2193 2194config DYNAMIC_MEMORY_LAYOUT 2195 bool 2196 help 2197 This option makes base addresses of vmalloc and vmemmap as well as 2198 __PAGE_OFFSET movable during boot. 2199 2200config RANDOMIZE_MEMORY 2201 bool "Randomize the kernel memory sections" 2202 depends on X86_64 2203 depends on RANDOMIZE_BASE 2204 select DYNAMIC_MEMORY_LAYOUT 2205 default RANDOMIZE_BASE 2206 help 2207 Randomizes the base virtual address of kernel memory sections 2208 (physical memory mapping, vmalloc & vmemmap). This security feature 2209 makes exploits relying on predictable memory locations less reliable. 2210 2211 The order of allocations remains unchanged. Entropy is generated in 2212 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2213 configuration have in average 30,000 different possible virtual 2214 addresses for each memory section. 2215 2216 If unsure, say Y. 2217 2218config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2219 hex "Physical memory mapping padding" if EXPERT 2220 depends on RANDOMIZE_MEMORY 2221 default "0xa" if MEMORY_HOTPLUG 2222 default "0x0" 2223 range 0x1 0x40 if MEMORY_HOTPLUG 2224 range 0x0 0x40 2225 help 2226 Define the padding in terabytes added to the existing physical 2227 memory size during kernel memory randomization. It is useful 2228 for memory hotplug support but reduces the entropy available for 2229 address randomization. 2230 2231 If unsure, leave at the default value. 2232 2233config HOTPLUG_CPU 2234 def_bool y 2235 depends on SMP 2236 2237config BOOTPARAM_HOTPLUG_CPU0 2238 bool "Set default setting of cpu0_hotpluggable" 2239 depends on HOTPLUG_CPU 2240 help 2241 Set whether default state of cpu0_hotpluggable is on or off. 2242 2243 Say Y here to enable CPU0 hotplug by default. If this switch 2244 is turned on, there is no need to give cpu0_hotplug kernel 2245 parameter and the CPU0 hotplug feature is enabled by default. 2246 2247 Please note: there are two known CPU0 dependencies if you want 2248 to enable the CPU0 hotplug feature either by this switch or by 2249 cpu0_hotplug kernel parameter. 2250 2251 First, resume from hibernate or suspend always starts from CPU0. 2252 So hibernate and suspend are prevented if CPU0 is offline. 2253 2254 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2255 offline if any interrupt can not migrate out of CPU0. There may 2256 be other CPU0 dependencies. 2257 2258 Please make sure the dependencies are under your control before 2259 you enable this feature. 2260 2261 Say N if you don't want to enable CPU0 hotplug feature by default. 2262 You still can enable the CPU0 hotplug feature at boot by kernel 2263 parameter cpu0_hotplug. 2264 2265config DEBUG_HOTPLUG_CPU0 2266 def_bool n 2267 prompt "Debug CPU0 hotplug" 2268 depends on HOTPLUG_CPU 2269 help 2270 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2271 soon as possible and boots up userspace with CPU0 offlined. User 2272 can online CPU0 back after boot time. 2273 2274 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2275 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2276 compilation or giving cpu0_hotplug kernel parameter at boot. 2277 2278 If unsure, say N. 2279 2280config COMPAT_VDSO 2281 def_bool n 2282 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2283 depends on COMPAT_32 2284 help 2285 Certain buggy versions of glibc will crash if they are 2286 presented with a 32-bit vDSO that is not mapped at the address 2287 indicated in its segment table. 2288 2289 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2290 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2291 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2292 the only released version with the bug, but OpenSUSE 9 2293 contains a buggy "glibc 2.3.2". 2294 2295 The symptom of the bug is that everything crashes on startup, saying: 2296 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2297 2298 Saying Y here changes the default value of the vdso32 boot 2299 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2300 This works around the glibc bug but hurts performance. 2301 2302 If unsure, say N: if you are compiling your own kernel, you 2303 are unlikely to be using a buggy version of glibc. 2304 2305choice 2306 prompt "vsyscall table for legacy applications" 2307 depends on X86_64 2308 default LEGACY_VSYSCALL_XONLY 2309 help 2310 Legacy user code that does not know how to find the vDSO expects 2311 to be able to issue three syscalls by calling fixed addresses in 2312 kernel space. Since this location is not randomized with ASLR, 2313 it can be used to assist security vulnerability exploitation. 2314 2315 This setting can be changed at boot time via the kernel command 2316 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2317 is deprecated and can only be enabled using the kernel command 2318 line. 2319 2320 On a system with recent enough glibc (2.14 or newer) and no 2321 static binaries, you can say None without a performance penalty 2322 to improve security. 2323 2324 If unsure, select "Emulate execution only". 2325 2326 config LEGACY_VSYSCALL_XONLY 2327 bool "Emulate execution only" 2328 help 2329 The kernel traps and emulates calls into the fixed vsyscall 2330 address mapping and does not allow reads. This 2331 configuration is recommended when userspace might use the 2332 legacy vsyscall area but support for legacy binary 2333 instrumentation of legacy code is not needed. It mitigates 2334 certain uses of the vsyscall area as an ASLR-bypassing 2335 buffer. 2336 2337 config LEGACY_VSYSCALL_NONE 2338 bool "None" 2339 help 2340 There will be no vsyscall mapping at all. This will 2341 eliminate any risk of ASLR bypass due to the vsyscall 2342 fixed address mapping. Attempts to use the vsyscalls 2343 will be reported to dmesg, so that either old or 2344 malicious userspace programs can be identified. 2345 2346endchoice 2347 2348config CMDLINE_BOOL 2349 bool "Built-in kernel command line" 2350 help 2351 Allow for specifying boot arguments to the kernel at 2352 build time. On some systems (e.g. embedded ones), it is 2353 necessary or convenient to provide some or all of the 2354 kernel boot arguments with the kernel itself (that is, 2355 to not rely on the boot loader to provide them.) 2356 2357 To compile command line arguments into the kernel, 2358 set this option to 'Y', then fill in the 2359 boot arguments in CONFIG_CMDLINE. 2360 2361 Systems with fully functional boot loaders (i.e. non-embedded) 2362 should leave this option set to 'N'. 2363 2364config CMDLINE 2365 string "Built-in kernel command string" 2366 depends on CMDLINE_BOOL 2367 default "" 2368 help 2369 Enter arguments here that should be compiled into the kernel 2370 image and used at boot time. If the boot loader provides a 2371 command line at boot time, it is appended to this string to 2372 form the full kernel command line, when the system boots. 2373 2374 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2375 change this behavior. 2376 2377 In most cases, the command line (whether built-in or provided 2378 by the boot loader) should specify the device for the root 2379 file system. 2380 2381config CMDLINE_OVERRIDE 2382 bool "Built-in command line overrides boot loader arguments" 2383 depends on CMDLINE_BOOL && CMDLINE != "" 2384 help 2385 Set this option to 'Y' to have the kernel ignore the boot loader 2386 command line, and use ONLY the built-in command line. 2387 2388 This is used to work around broken boot loaders. This should 2389 be set to 'N' under normal conditions. 2390 2391config MODIFY_LDT_SYSCALL 2392 bool "Enable the LDT (local descriptor table)" if EXPERT 2393 default y 2394 help 2395 Linux can allow user programs to install a per-process x86 2396 Local Descriptor Table (LDT) using the modify_ldt(2) system 2397 call. This is required to run 16-bit or segmented code such as 2398 DOSEMU or some Wine programs. It is also used by some very old 2399 threading libraries. 2400 2401 Enabling this feature adds a small amount of overhead to 2402 context switches and increases the low-level kernel attack 2403 surface. Disabling it removes the modify_ldt(2) system call. 2404 2405 Saying 'N' here may make sense for embedded or server kernels. 2406 2407config STRICT_SIGALTSTACK_SIZE 2408 bool "Enforce strict size checking for sigaltstack" 2409 depends on DYNAMIC_SIGFRAME 2410 help 2411 For historical reasons MINSIGSTKSZ is a constant which became 2412 already too small with AVX512 support. Add a mechanism to 2413 enforce strict checking of the sigaltstack size against the 2414 real size of the FPU frame. This option enables the check 2415 by default. It can also be controlled via the kernel command 2416 line option 'strict_sas_size' independent of this config 2417 switch. Enabling it might break existing applications which 2418 allocate a too small sigaltstack but 'work' because they 2419 never get a signal delivered. 2420 2421 Say 'N' unless you want to really enforce this check. 2422 2423source "kernel/livepatch/Kconfig" 2424 2425endmenu 2426 2427config CC_HAS_SLS 2428 def_bool $(cc-option,-mharden-sls=all) 2429 2430config CC_HAS_RETURN_THUNK 2431 def_bool $(cc-option,-mfunction-return=thunk-extern) 2432 2433menuconfig SPECULATION_MITIGATIONS 2434 bool "Mitigations for speculative execution vulnerabilities" 2435 default y 2436 help 2437 Say Y here to enable options which enable mitigations for 2438 speculative execution hardware vulnerabilities. 2439 2440 If you say N, all mitigations will be disabled. You really 2441 should know what you are doing to say so. 2442 2443if SPECULATION_MITIGATIONS 2444 2445config PAGE_TABLE_ISOLATION 2446 bool "Remove the kernel mapping in user mode" 2447 default y 2448 depends on (X86_64 || X86_PAE) 2449 help 2450 This feature reduces the number of hardware side channels by 2451 ensuring that the majority of kernel addresses are not mapped 2452 into userspace. 2453 2454 See Documentation/x86/pti.rst for more details. 2455 2456config RETPOLINE 2457 bool "Avoid speculative indirect branches in kernel" 2458 select OBJTOOL if HAVE_OBJTOOL 2459 default y 2460 help 2461 Compile kernel with the retpoline compiler options to guard against 2462 kernel-to-user data leaks by avoiding speculative indirect 2463 branches. Requires a compiler with -mindirect-branch=thunk-extern 2464 support for full protection. The kernel may run slower. 2465 2466config RETHUNK 2467 bool "Enable return-thunks" 2468 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2469 select OBJTOOL if HAVE_OBJTOOL 2470 default y if X86_64 2471 help 2472 Compile the kernel with the return-thunks compiler option to guard 2473 against kernel-to-user data leaks by avoiding return speculation. 2474 Requires a compiler with -mfunction-return=thunk-extern 2475 support for full protection. The kernel may run slower. 2476 2477config CPU_UNRET_ENTRY 2478 bool "Enable UNRET on kernel entry" 2479 depends on CPU_SUP_AMD && RETHUNK && X86_64 2480 default y 2481 help 2482 Compile the kernel with support for the retbleed=unret mitigation. 2483 2484config CPU_IBPB_ENTRY 2485 bool "Enable IBPB on kernel entry" 2486 depends on CPU_SUP_AMD && X86_64 2487 default y 2488 help 2489 Compile the kernel with support for the retbleed=ibpb mitigation. 2490 2491config CPU_IBRS_ENTRY 2492 bool "Enable IBRS on kernel entry" 2493 depends on CPU_SUP_INTEL && X86_64 2494 default y 2495 help 2496 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2497 This mitigates both spectre_v2 and retbleed at great cost to 2498 performance. 2499 2500config SLS 2501 bool "Mitigate Straight-Line-Speculation" 2502 depends on CC_HAS_SLS && X86_64 2503 select OBJTOOL if HAVE_OBJTOOL 2504 default n 2505 help 2506 Compile the kernel with straight-line-speculation options to guard 2507 against straight line speculation. The kernel image might be slightly 2508 larger. 2509 2510endif 2511 2512config ARCH_HAS_ADD_PAGES 2513 def_bool y 2514 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2515 2516config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2517 def_bool y 2518 2519menu "Power management and ACPI options" 2520 2521config ARCH_HIBERNATION_HEADER 2522 def_bool y 2523 depends on HIBERNATION 2524 2525source "kernel/power/Kconfig" 2526 2527source "drivers/acpi/Kconfig" 2528 2529config X86_APM_BOOT 2530 def_bool y 2531 depends on APM 2532 2533menuconfig APM 2534 tristate "APM (Advanced Power Management) BIOS support" 2535 depends on X86_32 && PM_SLEEP 2536 help 2537 APM is a BIOS specification for saving power using several different 2538 techniques. This is mostly useful for battery powered laptops with 2539 APM compliant BIOSes. If you say Y here, the system time will be 2540 reset after a RESUME operation, the /proc/apm device will provide 2541 battery status information, and user-space programs will receive 2542 notification of APM "events" (e.g. battery status change). 2543 2544 If you select "Y" here, you can disable actual use of the APM 2545 BIOS by passing the "apm=off" option to the kernel at boot time. 2546 2547 Note that the APM support is almost completely disabled for 2548 machines with more than one CPU. 2549 2550 In order to use APM, you will need supporting software. For location 2551 and more information, read <file:Documentation/power/apm-acpi.rst> 2552 and the Battery Powered Linux mini-HOWTO, available from 2553 <http://www.tldp.org/docs.html#howto>. 2554 2555 This driver does not spin down disk drives (see the hdparm(8) 2556 manpage ("man 8 hdparm") for that), and it doesn't turn off 2557 VESA-compliant "green" monitors. 2558 2559 This driver does not support the TI 4000M TravelMate and the ACER 2560 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2561 desktop machines also don't have compliant BIOSes, and this driver 2562 may cause those machines to panic during the boot phase. 2563 2564 Generally, if you don't have a battery in your machine, there isn't 2565 much point in using this driver and you should say N. If you get 2566 random kernel OOPSes or reboots that don't seem to be related to 2567 anything, try disabling/enabling this option (or disabling/enabling 2568 APM in your BIOS). 2569 2570 Some other things you should try when experiencing seemingly random, 2571 "weird" problems: 2572 2573 1) make sure that you have enough swap space and that it is 2574 enabled. 2575 2) pass the "no-hlt" option to the kernel 2576 3) switch on floating point emulation in the kernel and pass 2577 the "no387" option to the kernel 2578 4) pass the "floppy=nodma" option to the kernel 2579 5) pass the "mem=4M" option to the kernel (thereby disabling 2580 all but the first 4 MB of RAM) 2581 6) make sure that the CPU is not over clocked. 2582 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2583 8) disable the cache from your BIOS settings 2584 9) install a fan for the video card or exchange video RAM 2585 10) install a better fan for the CPU 2586 11) exchange RAM chips 2587 12) exchange the motherboard. 2588 2589 To compile this driver as a module, choose M here: the 2590 module will be called apm. 2591 2592if APM 2593 2594config APM_IGNORE_USER_SUSPEND 2595 bool "Ignore USER SUSPEND" 2596 help 2597 This option will ignore USER SUSPEND requests. On machines with a 2598 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2599 series notebooks, it is necessary to say Y because of a BIOS bug. 2600 2601config APM_DO_ENABLE 2602 bool "Enable PM at boot time" 2603 help 2604 Enable APM features at boot time. From page 36 of the APM BIOS 2605 specification: "When disabled, the APM BIOS does not automatically 2606 power manage devices, enter the Standby State, enter the Suspend 2607 State, or take power saving steps in response to CPU Idle calls." 2608 This driver will make CPU Idle calls when Linux is idle (unless this 2609 feature is turned off -- see "Do CPU IDLE calls", below). This 2610 should always save battery power, but more complicated APM features 2611 will be dependent on your BIOS implementation. You may need to turn 2612 this option off if your computer hangs at boot time when using APM 2613 support, or if it beeps continuously instead of suspending. Turn 2614 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2615 T400CDT. This is off by default since most machines do fine without 2616 this feature. 2617 2618config APM_CPU_IDLE 2619 depends on CPU_IDLE 2620 bool "Make CPU Idle calls when idle" 2621 help 2622 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2623 On some machines, this can activate improved power savings, such as 2624 a slowed CPU clock rate, when the machine is idle. These idle calls 2625 are made after the idle loop has run for some length of time (e.g., 2626 333 mS). On some machines, this will cause a hang at boot time or 2627 whenever the CPU becomes idle. (On machines with more than one CPU, 2628 this option does nothing.) 2629 2630config APM_DISPLAY_BLANK 2631 bool "Enable console blanking using APM" 2632 help 2633 Enable console blanking using the APM. Some laptops can use this to 2634 turn off the LCD backlight when the screen blanker of the Linux 2635 virtual console blanks the screen. Note that this is only used by 2636 the virtual console screen blanker, and won't turn off the backlight 2637 when using the X Window system. This also doesn't have anything to 2638 do with your VESA-compliant power-saving monitor. Further, this 2639 option doesn't work for all laptops -- it might not turn off your 2640 backlight at all, or it might print a lot of errors to the console, 2641 especially if you are using gpm. 2642 2643config APM_ALLOW_INTS 2644 bool "Allow interrupts during APM BIOS calls" 2645 help 2646 Normally we disable external interrupts while we are making calls to 2647 the APM BIOS as a measure to lessen the effects of a badly behaving 2648 BIOS implementation. The BIOS should reenable interrupts if it 2649 needs to. Unfortunately, some BIOSes do not -- especially those in 2650 many of the newer IBM Thinkpads. If you experience hangs when you 2651 suspend, try setting this to Y. Otherwise, say N. 2652 2653endif # APM 2654 2655source "drivers/cpufreq/Kconfig" 2656 2657source "drivers/cpuidle/Kconfig" 2658 2659source "drivers/idle/Kconfig" 2660 2661endmenu 2662 2663menu "Bus options (PCI etc.)" 2664 2665choice 2666 prompt "PCI access mode" 2667 depends on X86_32 && PCI 2668 default PCI_GOANY 2669 help 2670 On PCI systems, the BIOS can be used to detect the PCI devices and 2671 determine their configuration. However, some old PCI motherboards 2672 have BIOS bugs and may crash if this is done. Also, some embedded 2673 PCI-based systems don't have any BIOS at all. Linux can also try to 2674 detect the PCI hardware directly without using the BIOS. 2675 2676 With this option, you can specify how Linux should detect the 2677 PCI devices. If you choose "BIOS", the BIOS will be used, 2678 if you choose "Direct", the BIOS won't be used, and if you 2679 choose "MMConfig", then PCI Express MMCONFIG will be used. 2680 If you choose "Any", the kernel will try MMCONFIG, then the 2681 direct access method and falls back to the BIOS if that doesn't 2682 work. If unsure, go with the default, which is "Any". 2683 2684config PCI_GOBIOS 2685 bool "BIOS" 2686 2687config PCI_GOMMCONFIG 2688 bool "MMConfig" 2689 2690config PCI_GODIRECT 2691 bool "Direct" 2692 2693config PCI_GOOLPC 2694 bool "OLPC XO-1" 2695 depends on OLPC 2696 2697config PCI_GOANY 2698 bool "Any" 2699 2700endchoice 2701 2702config PCI_BIOS 2703 def_bool y 2704 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2705 2706# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2707config PCI_DIRECT 2708 def_bool y 2709 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2710 2711config PCI_MMCONFIG 2712 bool "Support mmconfig PCI config space access" if X86_64 2713 default y 2714 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2715 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2716 2717config PCI_OLPC 2718 def_bool y 2719 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2720 2721config PCI_XEN 2722 def_bool y 2723 depends on PCI && XEN 2724 2725config MMCONF_FAM10H 2726 def_bool y 2727 depends on X86_64 && PCI_MMCONFIG && ACPI 2728 2729config PCI_CNB20LE_QUIRK 2730 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2731 depends on PCI 2732 help 2733 Read the PCI windows out of the CNB20LE host bridge. This allows 2734 PCI hotplug to work on systems with the CNB20LE chipset which do 2735 not have ACPI. 2736 2737 There's no public spec for this chipset, and this functionality 2738 is known to be incomplete. 2739 2740 You should say N unless you know you need this. 2741 2742config ISA_BUS 2743 bool "ISA bus support on modern systems" if EXPERT 2744 help 2745 Expose ISA bus device drivers and options available for selection and 2746 configuration. Enable this option if your target machine has an ISA 2747 bus. ISA is an older system, displaced by PCI and newer bus 2748 architectures -- if your target machine is modern, it probably does 2749 not have an ISA bus. 2750 2751 If unsure, say N. 2752 2753# x86_64 have no ISA slots, but can have ISA-style DMA. 2754config ISA_DMA_API 2755 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2756 default y 2757 help 2758 Enables ISA-style DMA support for devices requiring such controllers. 2759 If unsure, say Y. 2760 2761if X86_32 2762 2763config ISA 2764 bool "ISA support" 2765 help 2766 Find out whether you have ISA slots on your motherboard. ISA is the 2767 name of a bus system, i.e. the way the CPU talks to the other stuff 2768 inside your box. Other bus systems are PCI, EISA, MicroChannel 2769 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2770 newer boards don't support it. If you have ISA, say Y, otherwise N. 2771 2772config SCx200 2773 tristate "NatSemi SCx200 support" 2774 help 2775 This provides basic support for National Semiconductor's 2776 (now AMD's) Geode processors. The driver probes for the 2777 PCI-IDs of several on-chip devices, so its a good dependency 2778 for other scx200_* drivers. 2779 2780 If compiled as a module, the driver is named scx200. 2781 2782config SCx200HR_TIMER 2783 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2784 depends on SCx200 2785 default y 2786 help 2787 This driver provides a clocksource built upon the on-chip 2788 27MHz high-resolution timer. Its also a workaround for 2789 NSC Geode SC-1100's buggy TSC, which loses time when the 2790 processor goes idle (as is done by the scheduler). The 2791 other workaround is idle=poll boot option. 2792 2793config OLPC 2794 bool "One Laptop Per Child support" 2795 depends on !X86_PAE 2796 select GPIOLIB 2797 select OF 2798 select OF_PROMTREE 2799 select IRQ_DOMAIN 2800 select OLPC_EC 2801 help 2802 Add support for detecting the unique features of the OLPC 2803 XO hardware. 2804 2805config OLPC_XO1_PM 2806 bool "OLPC XO-1 Power Management" 2807 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2808 help 2809 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2810 2811config OLPC_XO1_RTC 2812 bool "OLPC XO-1 Real Time Clock" 2813 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2814 help 2815 Add support for the XO-1 real time clock, which can be used as a 2816 programmable wakeup source. 2817 2818config OLPC_XO1_SCI 2819 bool "OLPC XO-1 SCI extras" 2820 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2821 depends on INPUT=y 2822 select POWER_SUPPLY 2823 help 2824 Add support for SCI-based features of the OLPC XO-1 laptop: 2825 - EC-driven system wakeups 2826 - Power button 2827 - Ebook switch 2828 - Lid switch 2829 - AC adapter status updates 2830 - Battery status updates 2831 2832config OLPC_XO15_SCI 2833 bool "OLPC XO-1.5 SCI extras" 2834 depends on OLPC && ACPI 2835 select POWER_SUPPLY 2836 help 2837 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2838 - EC-driven system wakeups 2839 - AC adapter status updates 2840 - Battery status updates 2841 2842config ALIX 2843 bool "PCEngines ALIX System Support (LED setup)" 2844 select GPIOLIB 2845 help 2846 This option enables system support for the PCEngines ALIX. 2847 At present this just sets up LEDs for GPIO control on 2848 ALIX2/3/6 boards. However, other system specific setup should 2849 get added here. 2850 2851 Note: You must still enable the drivers for GPIO and LED support 2852 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2853 2854 Note: You have to set alix.force=1 for boards with Award BIOS. 2855 2856config NET5501 2857 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2858 select GPIOLIB 2859 help 2860 This option enables system support for the Soekris Engineering net5501. 2861 2862config GEOS 2863 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2864 select GPIOLIB 2865 depends on DMI 2866 help 2867 This option enables system support for the Traverse Technologies GEOS. 2868 2869config TS5500 2870 bool "Technologic Systems TS-5500 platform support" 2871 depends on MELAN 2872 select CHECK_SIGNATURE 2873 select NEW_LEDS 2874 select LEDS_CLASS 2875 help 2876 This option enables system support for the Technologic Systems TS-5500. 2877 2878endif # X86_32 2879 2880config AMD_NB 2881 def_bool y 2882 depends on CPU_SUP_AMD && PCI 2883 2884endmenu 2885 2886menu "Binary Emulations" 2887 2888config IA32_EMULATION 2889 bool "IA32 Emulation" 2890 depends on X86_64 2891 select ARCH_WANT_OLD_COMPAT_IPC 2892 select BINFMT_ELF 2893 select COMPAT_OLD_SIGACTION 2894 help 2895 Include code to run legacy 32-bit programs under a 2896 64-bit kernel. You should likely turn this on, unless you're 2897 100% sure that you don't have any 32-bit programs left. 2898 2899config X86_X32_ABI 2900 bool "x32 ABI for 64-bit mode" 2901 depends on X86_64 2902 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2903 # compressed debug sections to x86_x32 properly: 2904 # https://github.com/ClangBuiltLinux/linux/issues/514 2905 # https://github.com/ClangBuiltLinux/linux/issues/1141 2906 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 2907 help 2908 Include code to run binaries for the x32 native 32-bit ABI 2909 for 64-bit processors. An x32 process gets access to the 2910 full 64-bit register file and wide data path while leaving 2911 pointers at 32 bits for smaller memory footprint. 2912 2913config COMPAT_32 2914 def_bool y 2915 depends on IA32_EMULATION || X86_32 2916 select HAVE_UID16 2917 select OLD_SIGSUSPEND3 2918 2919config COMPAT 2920 def_bool y 2921 depends on IA32_EMULATION || X86_X32_ABI 2922 2923config COMPAT_FOR_U64_ALIGNMENT 2924 def_bool y 2925 depends on COMPAT 2926 2927endmenu 2928 2929config HAVE_ATOMIC_IOMAP 2930 def_bool y 2931 depends on X86_32 2932 2933source "arch/x86/kvm/Kconfig" 2934 2935source "arch/x86/Kconfig.assembler" 2936