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