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_VM_GET_PAGE_PROT 98 select ARCH_HAS_DEBUG_WX 99 select ARCH_HAS_ZONE_DMA_SET if EXPERT 100 select ARCH_HAVE_NMI_SAFE_CMPXCHG 101 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 102 select ARCH_MIGHT_HAVE_PC_PARPORT 103 select ARCH_MIGHT_HAVE_PC_SERIO 104 select ARCH_STACKWALK 105 select ARCH_SUPPORTS_ACPI 106 select ARCH_SUPPORTS_ATOMIC_RMW 107 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 108 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 109 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 110 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 111 select ARCH_SUPPORTS_LTO_CLANG 112 select ARCH_SUPPORTS_LTO_CLANG_THIN 113 select ARCH_USE_BUILTIN_BSWAP 114 select ARCH_USE_MEMTEST 115 select ARCH_USE_QUEUED_RWLOCKS 116 select ARCH_USE_QUEUED_SPINLOCKS 117 select ARCH_USE_SYM_ANNOTATIONS 118 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 119 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 120 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 121 select ARCH_WANTS_NO_INSTR 122 select ARCH_WANT_GENERAL_HUGETLB 123 select ARCH_WANT_HUGE_PMD_SHARE 124 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64 125 select ARCH_WANT_LD_ORPHAN_WARN 126 select ARCH_WANTS_THP_SWAP if X86_64 127 select ARCH_HAS_PARANOID_L1D_FLUSH 128 select BUILDTIME_TABLE_SORT 129 select CLKEVT_I8253 130 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 131 select CLOCKSOURCE_WATCHDOG 132 select DCACHE_WORD_ACCESS 133 select DYNAMIC_SIGFRAME 134 select EDAC_ATOMIC_SCRUB 135 select EDAC_SUPPORT 136 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 137 select GENERIC_CLOCKEVENTS_MIN_ADJUST 138 select GENERIC_CMOS_UPDATE 139 select GENERIC_CPU_AUTOPROBE 140 select GENERIC_CPU_VULNERABILITIES 141 select GENERIC_EARLY_IOREMAP 142 select GENERIC_ENTRY 143 select GENERIC_IOMAP 144 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 145 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 146 select GENERIC_IRQ_MIGRATION if SMP 147 select GENERIC_IRQ_PROBE 148 select GENERIC_IRQ_RESERVATION_MODE 149 select GENERIC_IRQ_SHOW 150 select GENERIC_PENDING_IRQ if SMP 151 select GENERIC_PTDUMP 152 select GENERIC_SMP_IDLE_THREAD 153 select GENERIC_TIME_VSYSCALL 154 select GENERIC_GETTIMEOFDAY 155 select GENERIC_VDSO_TIME_NS 156 select GUP_GET_PTE_LOW_HIGH if X86_PAE 157 select HARDIRQS_SW_RESEND 158 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 159 select HAVE_ACPI_APEI if ACPI 160 select HAVE_ACPI_APEI_NMI if ACPI 161 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 162 select HAVE_ARCH_AUDITSYSCALL 163 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 164 select HAVE_ARCH_HUGE_VMALLOC if X86_64 165 select HAVE_ARCH_JUMP_LABEL 166 select HAVE_ARCH_JUMP_LABEL_RELATIVE 167 select HAVE_ARCH_KASAN if X86_64 168 select HAVE_ARCH_KASAN_VMALLOC if X86_64 169 select HAVE_ARCH_KFENCE 170 select HAVE_ARCH_KGDB 171 select HAVE_ARCH_MMAP_RND_BITS if MMU 172 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 173 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 174 select HAVE_ARCH_PREL32_RELOCATIONS 175 select HAVE_ARCH_SECCOMP_FILTER 176 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 177 select HAVE_ARCH_STACKLEAK 178 select HAVE_ARCH_TRACEHOOK 179 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 180 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 181 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 182 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 183 select HAVE_ARCH_VMAP_STACK if X86_64 184 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 185 select HAVE_ARCH_WITHIN_STACK_FRAMES 186 select HAVE_ASM_MODVERSIONS 187 select HAVE_CMPXCHG_DOUBLE 188 select HAVE_CMPXCHG_LOCAL 189 select HAVE_CONTEXT_TRACKING if X86_64 190 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING 191 select HAVE_C_RECORDMCOUNT 192 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 193 select HAVE_BUILDTIME_MCOUNT_SORT 194 select HAVE_DEBUG_KMEMLEAK 195 select HAVE_DMA_CONTIGUOUS 196 select HAVE_DYNAMIC_FTRACE 197 select HAVE_DYNAMIC_FTRACE_WITH_REGS 198 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 199 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 200 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 201 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 202 select HAVE_EBPF_JIT 203 select HAVE_EFFICIENT_UNALIGNED_ACCESS 204 select HAVE_EISA 205 select HAVE_EXIT_THREAD 206 select HAVE_FAST_GUP 207 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 208 select HAVE_FTRACE_MCOUNT_RECORD 209 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 210 select HAVE_FUNCTION_TRACER 211 select HAVE_GCC_PLUGINS 212 select HAVE_HW_BREAKPOINT 213 select HAVE_IOREMAP_PROT 214 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 215 select HAVE_IRQ_TIME_ACCOUNTING 216 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 217 select HAVE_KERNEL_BZIP2 218 select HAVE_KERNEL_GZIP 219 select HAVE_KERNEL_LZ4 220 select HAVE_KERNEL_LZMA 221 select HAVE_KERNEL_LZO 222 select HAVE_KERNEL_XZ 223 select HAVE_KERNEL_ZSTD 224 select HAVE_KPROBES 225 select HAVE_KPROBES_ON_FTRACE 226 select HAVE_FUNCTION_ERROR_INJECTION 227 select HAVE_KRETPROBES 228 select HAVE_RETHOOK 229 select HAVE_KVM 230 select HAVE_LIVEPATCH if X86_64 231 select HAVE_MIXED_BREAKPOINTS_REGS 232 select HAVE_MOD_ARCH_SPECIFIC 233 select HAVE_MOVE_PMD 234 select HAVE_MOVE_PUD 235 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 236 select HAVE_NMI 237 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 238 select HAVE_OBJTOOL if X86_64 239 select HAVE_OPTPROBES 240 select HAVE_PCSPKR_PLATFORM 241 select HAVE_PERF_EVENTS 242 select HAVE_PERF_EVENTS_NMI 243 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 244 select HAVE_PCI 245 select HAVE_PERF_REGS 246 select HAVE_PERF_USER_STACK_DUMP 247 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 248 select 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 USER_STACKTRACE_SUPPORT 281 select VIRT_TO_BUS 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)) if 64BIT 395 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC)) 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 ARCH_RANDOM 1814 def_bool y 1815 prompt "x86 architectural random number generator" if EXPERT 1816 help 1817 Enable the x86 architectural RDRAND instruction 1818 (Intel Bull Mountain technology) to generate random numbers. 1819 If supported, this is a high bandwidth, cryptographically 1820 secure hardware random number generator. 1821 1822config X86_UMIP 1823 def_bool y 1824 prompt "User Mode Instruction Prevention" if EXPERT 1825 help 1826 User Mode Instruction Prevention (UMIP) is a security feature in 1827 some x86 processors. If enabled, a general protection fault is 1828 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1829 executed in user mode. These instructions unnecessarily expose 1830 information about the hardware state. 1831 1832 The vast majority of applications do not use these instructions. 1833 For the very few that do, software emulation is provided in 1834 specific cases in protected and virtual-8086 modes. Emulated 1835 results are dummy. 1836 1837config CC_HAS_IBT 1838 # GCC >= 9 and binutils >= 2.29 1839 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1840 # Clang/LLVM >= 14 1841 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1842 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1843 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1844 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1845 $(as-instr,endbr64) 1846 1847config X86_KERNEL_IBT 1848 prompt "Indirect Branch Tracking" 1849 bool 1850 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1851 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1852 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1853 select OBJTOOL 1854 help 1855 Build the kernel with support for Indirect Branch Tracking, a 1856 hardware support course-grain forward-edge Control Flow Integrity 1857 protection. It enforces that all indirect calls must land on 1858 an ENDBR instruction, as such, the compiler will instrument the 1859 code with them to make this happen. 1860 1861 In addition to building the kernel with IBT, seal all functions that 1862 are not indirect call targets, avoiding them ever becoming one. 1863 1864 This requires LTO like objtool runs and will slow down the build. It 1865 does significantly reduce the number of ENDBR instructions in the 1866 kernel image. 1867 1868config X86_INTEL_MEMORY_PROTECTION_KEYS 1869 prompt "Memory Protection Keys" 1870 def_bool y 1871 # Note: only available in 64-bit mode 1872 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1873 select ARCH_USES_HIGH_VMA_FLAGS 1874 select ARCH_HAS_PKEYS 1875 help 1876 Memory Protection Keys provides a mechanism for enforcing 1877 page-based protections, but without requiring modification of the 1878 page tables when an application changes protection domains. 1879 1880 For details, see Documentation/core-api/protection-keys.rst 1881 1882 If unsure, say y. 1883 1884choice 1885 prompt "TSX enable mode" 1886 depends on CPU_SUP_INTEL 1887 default X86_INTEL_TSX_MODE_OFF 1888 help 1889 Intel's TSX (Transactional Synchronization Extensions) feature 1890 allows to optimize locking protocols through lock elision which 1891 can lead to a noticeable performance boost. 1892 1893 On the other hand it has been shown that TSX can be exploited 1894 to form side channel attacks (e.g. TAA) and chances are there 1895 will be more of those attacks discovered in the future. 1896 1897 Therefore TSX is not enabled by default (aka tsx=off). An admin 1898 might override this decision by tsx=on the command line parameter. 1899 Even with TSX enabled, the kernel will attempt to enable the best 1900 possible TAA mitigation setting depending on the microcode available 1901 for the particular machine. 1902 1903 This option allows to set the default tsx mode between tsx=on, =off 1904 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1905 details. 1906 1907 Say off if not sure, auto if TSX is in use but it should be used on safe 1908 platforms or on if TSX is in use and the security aspect of tsx is not 1909 relevant. 1910 1911config X86_INTEL_TSX_MODE_OFF 1912 bool "off" 1913 help 1914 TSX is disabled if possible - equals to tsx=off command line parameter. 1915 1916config X86_INTEL_TSX_MODE_ON 1917 bool "on" 1918 help 1919 TSX is always enabled on TSX capable HW - equals the tsx=on command 1920 line parameter. 1921 1922config X86_INTEL_TSX_MODE_AUTO 1923 bool "auto" 1924 help 1925 TSX is enabled on TSX capable HW that is believed to be safe against 1926 side channel attacks- equals the tsx=auto command line parameter. 1927endchoice 1928 1929config X86_SGX 1930 bool "Software Guard eXtensions (SGX)" 1931 depends on X86_64 && CPU_SUP_INTEL 1932 depends on CRYPTO=y 1933 depends on CRYPTO_SHA256=y 1934 select SRCU 1935 select MMU_NOTIFIER 1936 select NUMA_KEEP_MEMINFO if NUMA 1937 select XARRAY_MULTI 1938 help 1939 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1940 that can be used by applications to set aside private regions of code 1941 and data, referred to as enclaves. An enclave's private memory can 1942 only be accessed by code running within the enclave. Accesses from 1943 outside the enclave, including other enclaves, are disallowed by 1944 hardware. 1945 1946 If unsure, say N. 1947 1948config EFI 1949 bool "EFI runtime service support" 1950 depends on ACPI 1951 select UCS2_STRING 1952 select EFI_RUNTIME_WRAPPERS 1953 select ARCH_USE_MEMREMAP_PROT 1954 help 1955 This enables the kernel to use EFI runtime services that are 1956 available (such as the EFI variable services). 1957 1958 This option is only useful on systems that have EFI firmware. 1959 In addition, you should use the latest ELILO loader available 1960 at <http://elilo.sourceforge.net> in order to take advantage 1961 of EFI runtime services. However, even with this option, the 1962 resultant kernel should continue to boot on existing non-EFI 1963 platforms. 1964 1965config EFI_STUB 1966 bool "EFI stub support" 1967 depends on EFI 1968 depends on $(cc-option,-mabi=ms) || X86_32 1969 select RELOCATABLE 1970 help 1971 This kernel feature allows a bzImage to be loaded directly 1972 by EFI firmware without the use of a bootloader. 1973 1974 See Documentation/admin-guide/efi-stub.rst for more information. 1975 1976config EFI_MIXED 1977 bool "EFI mixed-mode support" 1978 depends on EFI_STUB && X86_64 1979 help 1980 Enabling this feature allows a 64-bit kernel to be booted 1981 on a 32-bit firmware, provided that your CPU supports 64-bit 1982 mode. 1983 1984 Note that it is not possible to boot a mixed-mode enabled 1985 kernel via the EFI boot stub - a bootloader that supports 1986 the EFI handover protocol must be used. 1987 1988 If unsure, say N. 1989 1990source "kernel/Kconfig.hz" 1991 1992config KEXEC 1993 bool "kexec system call" 1994 select KEXEC_CORE 1995 help 1996 kexec is a system call that implements the ability to shutdown your 1997 current kernel, and to start another kernel. It is like a reboot 1998 but it is independent of the system firmware. And like a reboot 1999 you can start any kernel with it, not just Linux. 2000 2001 The name comes from the similarity to the exec system call. 2002 2003 It is an ongoing process to be certain the hardware in a machine 2004 is properly shutdown, so do not be surprised if this code does not 2005 initially work for you. As of this writing the exact hardware 2006 interface is strongly in flux, so no good recommendation can be 2007 made. 2008 2009config KEXEC_FILE 2010 bool "kexec file based system call" 2011 select KEXEC_CORE 2012 select BUILD_BIN2C 2013 depends on X86_64 2014 depends on CRYPTO=y 2015 depends on CRYPTO_SHA256=y 2016 help 2017 This is new version of kexec system call. This system call is 2018 file based and takes file descriptors as system call argument 2019 for kernel and initramfs as opposed to list of segments as 2020 accepted by previous system call. 2021 2022config ARCH_HAS_KEXEC_PURGATORY 2023 def_bool KEXEC_FILE 2024 2025config KEXEC_SIG 2026 bool "Verify kernel signature during kexec_file_load() syscall" 2027 depends on KEXEC_FILE 2028 help 2029 2030 This option makes the kexec_file_load() syscall check for a valid 2031 signature of the kernel image. The image can still be loaded without 2032 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2033 there's a signature that we can check, then it must be valid. 2034 2035 In addition to this option, you need to enable signature 2036 verification for the corresponding kernel image type being 2037 loaded in order for this to work. 2038 2039config KEXEC_SIG_FORCE 2040 bool "Require a valid signature in kexec_file_load() syscall" 2041 depends on KEXEC_SIG 2042 help 2043 This option makes kernel signature verification mandatory for 2044 the kexec_file_load() syscall. 2045 2046config KEXEC_BZIMAGE_VERIFY_SIG 2047 bool "Enable bzImage signature verification support" 2048 depends on KEXEC_SIG 2049 depends on SIGNED_PE_FILE_VERIFICATION 2050 select SYSTEM_TRUSTED_KEYRING 2051 help 2052 Enable bzImage signature verification support. 2053 2054config CRASH_DUMP 2055 bool "kernel crash dumps" 2056 depends on X86_64 || (X86_32 && HIGHMEM) 2057 help 2058 Generate crash dump after being started by kexec. 2059 This should be normally only set in special crash dump kernels 2060 which are loaded in the main kernel with kexec-tools into 2061 a specially reserved region and then later executed after 2062 a crash by kdump/kexec. The crash dump kernel must be compiled 2063 to a memory address not used by the main kernel or BIOS using 2064 PHYSICAL_START, or it must be built as a relocatable image 2065 (CONFIG_RELOCATABLE=y). 2066 For more details see Documentation/admin-guide/kdump/kdump.rst 2067 2068config KEXEC_JUMP 2069 bool "kexec jump" 2070 depends on KEXEC && HIBERNATION 2071 help 2072 Jump between original kernel and kexeced kernel and invoke 2073 code in physical address mode via KEXEC 2074 2075config PHYSICAL_START 2076 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2077 default "0x1000000" 2078 help 2079 This gives the physical address where the kernel is loaded. 2080 2081 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2082 bzImage will decompress itself to above physical address and 2083 run from there. Otherwise, bzImage will run from the address where 2084 it has been loaded by the boot loader and will ignore above physical 2085 address. 2086 2087 In normal kdump cases one does not have to set/change this option 2088 as now bzImage can be compiled as a completely relocatable image 2089 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2090 address. This option is mainly useful for the folks who don't want 2091 to use a bzImage for capturing the crash dump and want to use a 2092 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2093 to be specifically compiled to run from a specific memory area 2094 (normally a reserved region) and this option comes handy. 2095 2096 So if you are using bzImage for capturing the crash dump, 2097 leave the value here unchanged to 0x1000000 and set 2098 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2099 for capturing the crash dump change this value to start of 2100 the reserved region. In other words, it can be set based on 2101 the "X" value as specified in the "crashkernel=YM@XM" 2102 command line boot parameter passed to the panic-ed 2103 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2104 for more details about crash dumps. 2105 2106 Usage of bzImage for capturing the crash dump is recommended as 2107 one does not have to build two kernels. Same kernel can be used 2108 as production kernel and capture kernel. Above option should have 2109 gone away after relocatable bzImage support is introduced. But it 2110 is present because there are users out there who continue to use 2111 vmlinux for dump capture. This option should go away down the 2112 line. 2113 2114 Don't change this unless you know what you are doing. 2115 2116config RELOCATABLE 2117 bool "Build a relocatable kernel" 2118 default y 2119 help 2120 This builds a kernel image that retains relocation information 2121 so it can be loaded someplace besides the default 1MB. 2122 The relocations tend to make the kernel binary about 10% larger, 2123 but are discarded at runtime. 2124 2125 One use is for the kexec on panic case where the recovery kernel 2126 must live at a different physical address than the primary 2127 kernel. 2128 2129 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2130 it has been loaded at and the compile time physical address 2131 (CONFIG_PHYSICAL_START) is used as the minimum location. 2132 2133config RANDOMIZE_BASE 2134 bool "Randomize the address of the kernel image (KASLR)" 2135 depends on RELOCATABLE 2136 default y 2137 help 2138 In support of Kernel Address Space Layout Randomization (KASLR), 2139 this randomizes the physical address at which the kernel image 2140 is decompressed and the virtual address where the kernel 2141 image is mapped, as a security feature that deters exploit 2142 attempts relying on knowledge of the location of kernel 2143 code internals. 2144 2145 On 64-bit, the kernel physical and virtual addresses are 2146 randomized separately. The physical address will be anywhere 2147 between 16MB and the top of physical memory (up to 64TB). The 2148 virtual address will be randomized from 16MB up to 1GB (9 bits 2149 of entropy). Note that this also reduces the memory space 2150 available to kernel modules from 1.5GB to 1GB. 2151 2152 On 32-bit, the kernel physical and virtual addresses are 2153 randomized together. They will be randomized from 16MB up to 2154 512MB (8 bits of entropy). 2155 2156 Entropy is generated using the RDRAND instruction if it is 2157 supported. If RDTSC is supported, its value is mixed into 2158 the entropy pool as well. If neither RDRAND nor RDTSC are 2159 supported, then entropy is read from the i8254 timer. The 2160 usable entropy is limited by the kernel being built using 2161 2GB addressing, and that PHYSICAL_ALIGN must be at a 2162 minimum of 2MB. As a result, only 10 bits of entropy are 2163 theoretically possible, but the implementations are further 2164 limited due to memory layouts. 2165 2166 If unsure, say Y. 2167 2168# Relocation on x86 needs some additional build support 2169config X86_NEED_RELOCS 2170 def_bool y 2171 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2172 2173config PHYSICAL_ALIGN 2174 hex "Alignment value to which kernel should be aligned" 2175 default "0x200000" 2176 range 0x2000 0x1000000 if X86_32 2177 range 0x200000 0x1000000 if X86_64 2178 help 2179 This value puts the alignment restrictions on physical address 2180 where kernel is loaded and run from. Kernel is compiled for an 2181 address which meets above alignment restriction. 2182 2183 If bootloader loads the kernel at a non-aligned address and 2184 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2185 address aligned to above value and run from there. 2186 2187 If bootloader loads the kernel at a non-aligned address and 2188 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2189 load address and decompress itself to the address it has been 2190 compiled for and run from there. The address for which kernel is 2191 compiled already meets above alignment restrictions. Hence the 2192 end result is that kernel runs from a physical address meeting 2193 above alignment restrictions. 2194 2195 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2196 this value must be a multiple of 0x200000. 2197 2198 Don't change this unless you know what you are doing. 2199 2200config DYNAMIC_MEMORY_LAYOUT 2201 bool 2202 help 2203 This option makes base addresses of vmalloc and vmemmap as well as 2204 __PAGE_OFFSET movable during boot. 2205 2206config RANDOMIZE_MEMORY 2207 bool "Randomize the kernel memory sections" 2208 depends on X86_64 2209 depends on RANDOMIZE_BASE 2210 select DYNAMIC_MEMORY_LAYOUT 2211 default RANDOMIZE_BASE 2212 help 2213 Randomizes the base virtual address of kernel memory sections 2214 (physical memory mapping, vmalloc & vmemmap). This security feature 2215 makes exploits relying on predictable memory locations less reliable. 2216 2217 The order of allocations remains unchanged. Entropy is generated in 2218 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2219 configuration have in average 30,000 different possible virtual 2220 addresses for each memory section. 2221 2222 If unsure, say Y. 2223 2224config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2225 hex "Physical memory mapping padding" if EXPERT 2226 depends on RANDOMIZE_MEMORY 2227 default "0xa" if MEMORY_HOTPLUG 2228 default "0x0" 2229 range 0x1 0x40 if MEMORY_HOTPLUG 2230 range 0x0 0x40 2231 help 2232 Define the padding in terabytes added to the existing physical 2233 memory size during kernel memory randomization. It is useful 2234 for memory hotplug support but reduces the entropy available for 2235 address randomization. 2236 2237 If unsure, leave at the default value. 2238 2239config HOTPLUG_CPU 2240 def_bool y 2241 depends on SMP 2242 2243config BOOTPARAM_HOTPLUG_CPU0 2244 bool "Set default setting of cpu0_hotpluggable" 2245 depends on HOTPLUG_CPU 2246 help 2247 Set whether default state of cpu0_hotpluggable is on or off. 2248 2249 Say Y here to enable CPU0 hotplug by default. If this switch 2250 is turned on, there is no need to give cpu0_hotplug kernel 2251 parameter and the CPU0 hotplug feature is enabled by default. 2252 2253 Please note: there are two known CPU0 dependencies if you want 2254 to enable the CPU0 hotplug feature either by this switch or by 2255 cpu0_hotplug kernel parameter. 2256 2257 First, resume from hibernate or suspend always starts from CPU0. 2258 So hibernate and suspend are prevented if CPU0 is offline. 2259 2260 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2261 offline if any interrupt can not migrate out of CPU0. There may 2262 be other CPU0 dependencies. 2263 2264 Please make sure the dependencies are under your control before 2265 you enable this feature. 2266 2267 Say N if you don't want to enable CPU0 hotplug feature by default. 2268 You still can enable the CPU0 hotplug feature at boot by kernel 2269 parameter cpu0_hotplug. 2270 2271config DEBUG_HOTPLUG_CPU0 2272 def_bool n 2273 prompt "Debug CPU0 hotplug" 2274 depends on HOTPLUG_CPU 2275 help 2276 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2277 soon as possible and boots up userspace with CPU0 offlined. User 2278 can online CPU0 back after boot time. 2279 2280 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2281 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2282 compilation or giving cpu0_hotplug kernel parameter at boot. 2283 2284 If unsure, say N. 2285 2286config COMPAT_VDSO 2287 def_bool n 2288 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2289 depends on COMPAT_32 2290 help 2291 Certain buggy versions of glibc will crash if they are 2292 presented with a 32-bit vDSO that is not mapped at the address 2293 indicated in its segment table. 2294 2295 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2296 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2297 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2298 the only released version with the bug, but OpenSUSE 9 2299 contains a buggy "glibc 2.3.2". 2300 2301 The symptom of the bug is that everything crashes on startup, saying: 2302 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2303 2304 Saying Y here changes the default value of the vdso32 boot 2305 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2306 This works around the glibc bug but hurts performance. 2307 2308 If unsure, say N: if you are compiling your own kernel, you 2309 are unlikely to be using a buggy version of glibc. 2310 2311choice 2312 prompt "vsyscall table for legacy applications" 2313 depends on X86_64 2314 default LEGACY_VSYSCALL_XONLY 2315 help 2316 Legacy user code that does not know how to find the vDSO expects 2317 to be able to issue three syscalls by calling fixed addresses in 2318 kernel space. Since this location is not randomized with ASLR, 2319 it can be used to assist security vulnerability exploitation. 2320 2321 This setting can be changed at boot time via the kernel command 2322 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2323 is deprecated and can only be enabled using the kernel command 2324 line. 2325 2326 On a system with recent enough glibc (2.14 or newer) and no 2327 static binaries, you can say None without a performance penalty 2328 to improve security. 2329 2330 If unsure, select "Emulate execution only". 2331 2332 config LEGACY_VSYSCALL_XONLY 2333 bool "Emulate execution only" 2334 help 2335 The kernel traps and emulates calls into the fixed vsyscall 2336 address mapping and does not allow reads. This 2337 configuration is recommended when userspace might use the 2338 legacy vsyscall area but support for legacy binary 2339 instrumentation of legacy code is not needed. It mitigates 2340 certain uses of the vsyscall area as an ASLR-bypassing 2341 buffer. 2342 2343 config LEGACY_VSYSCALL_NONE 2344 bool "None" 2345 help 2346 There will be no vsyscall mapping at all. This will 2347 eliminate any risk of ASLR bypass due to the vsyscall 2348 fixed address mapping. Attempts to use the vsyscalls 2349 will be reported to dmesg, so that either old or 2350 malicious userspace programs can be identified. 2351 2352endchoice 2353 2354config CMDLINE_BOOL 2355 bool "Built-in kernel command line" 2356 help 2357 Allow for specifying boot arguments to the kernel at 2358 build time. On some systems (e.g. embedded ones), it is 2359 necessary or convenient to provide some or all of the 2360 kernel boot arguments with the kernel itself (that is, 2361 to not rely on the boot loader to provide them.) 2362 2363 To compile command line arguments into the kernel, 2364 set this option to 'Y', then fill in the 2365 boot arguments in CONFIG_CMDLINE. 2366 2367 Systems with fully functional boot loaders (i.e. non-embedded) 2368 should leave this option set to 'N'. 2369 2370config CMDLINE 2371 string "Built-in kernel command string" 2372 depends on CMDLINE_BOOL 2373 default "" 2374 help 2375 Enter arguments here that should be compiled into the kernel 2376 image and used at boot time. If the boot loader provides a 2377 command line at boot time, it is appended to this string to 2378 form the full kernel command line, when the system boots. 2379 2380 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2381 change this behavior. 2382 2383 In most cases, the command line (whether built-in or provided 2384 by the boot loader) should specify the device for the root 2385 file system. 2386 2387config CMDLINE_OVERRIDE 2388 bool "Built-in command line overrides boot loader arguments" 2389 depends on CMDLINE_BOOL && CMDLINE != "" 2390 help 2391 Set this option to 'Y' to have the kernel ignore the boot loader 2392 command line, and use ONLY the built-in command line. 2393 2394 This is used to work around broken boot loaders. This should 2395 be set to 'N' under normal conditions. 2396 2397config MODIFY_LDT_SYSCALL 2398 bool "Enable the LDT (local descriptor table)" if EXPERT 2399 default y 2400 help 2401 Linux can allow user programs to install a per-process x86 2402 Local Descriptor Table (LDT) using the modify_ldt(2) system 2403 call. This is required to run 16-bit or segmented code such as 2404 DOSEMU or some Wine programs. It is also used by some very old 2405 threading libraries. 2406 2407 Enabling this feature adds a small amount of overhead to 2408 context switches and increases the low-level kernel attack 2409 surface. Disabling it removes the modify_ldt(2) system call. 2410 2411 Saying 'N' here may make sense for embedded or server kernels. 2412 2413config STRICT_SIGALTSTACK_SIZE 2414 bool "Enforce strict size checking for sigaltstack" 2415 depends on DYNAMIC_SIGFRAME 2416 help 2417 For historical reasons MINSIGSTKSZ is a constant which became 2418 already too small with AVX512 support. Add a mechanism to 2419 enforce strict checking of the sigaltstack size against the 2420 real size of the FPU frame. This option enables the check 2421 by default. It can also be controlled via the kernel command 2422 line option 'strict_sas_size' independent of this config 2423 switch. Enabling it might break existing applications which 2424 allocate a too small sigaltstack but 'work' because they 2425 never get a signal delivered. 2426 2427 Say 'N' unless you want to really enforce this check. 2428 2429source "kernel/livepatch/Kconfig" 2430 2431endmenu 2432 2433config CC_HAS_SLS 2434 def_bool $(cc-option,-mharden-sls=all) 2435 2436config CC_HAS_RETURN_THUNK 2437 def_bool $(cc-option,-mfunction-return=thunk-extern) 2438 2439menuconfig SPECULATION_MITIGATIONS 2440 bool "Mitigations for speculative execution vulnerabilities" 2441 default y 2442 help 2443 Say Y here to enable options which enable mitigations for 2444 speculative execution hardware vulnerabilities. 2445 2446 If you say N, all mitigations will be disabled. You really 2447 should know what you are doing to say so. 2448 2449if SPECULATION_MITIGATIONS 2450 2451config PAGE_TABLE_ISOLATION 2452 bool "Remove the kernel mapping in user mode" 2453 default y 2454 depends on (X86_64 || X86_PAE) 2455 help 2456 This feature reduces the number of hardware side channels by 2457 ensuring that the majority of kernel addresses are not mapped 2458 into userspace. 2459 2460 See Documentation/x86/pti.rst for more details. 2461 2462config RETPOLINE 2463 bool "Avoid speculative indirect branches in kernel" 2464 select OBJTOOL if HAVE_OBJTOOL 2465 default y 2466 help 2467 Compile kernel with the retpoline compiler options to guard against 2468 kernel-to-user data leaks by avoiding speculative indirect 2469 branches. Requires a compiler with -mindirect-branch=thunk-extern 2470 support for full protection. The kernel may run slower. 2471 2472config RETHUNK 2473 bool "Enable return-thunks" 2474 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2475 select OBJTOOL if HAVE_OBJTOOL 2476 default y 2477 help 2478 Compile the kernel with the return-thunks compiler option to guard 2479 against kernel-to-user data leaks by avoiding return speculation. 2480 Requires a compiler with -mfunction-return=thunk-extern 2481 support for full protection. The kernel may run slower. 2482 2483config CPU_UNRET_ENTRY 2484 bool "Enable UNRET on kernel entry" 2485 depends on CPU_SUP_AMD && RETHUNK 2486 default y 2487 help 2488 Compile the kernel with support for the retbleed=unret mitigation. 2489 2490config CPU_IBPB_ENTRY 2491 bool "Enable IBPB on kernel entry" 2492 depends on CPU_SUP_AMD 2493 default y 2494 help 2495 Compile the kernel with support for the retbleed=ibpb mitigation. 2496 2497config CPU_IBRS_ENTRY 2498 bool "Enable IBRS on kernel entry" 2499 depends on CPU_SUP_INTEL 2500 default y 2501 help 2502 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2503 This mitigates both spectre_v2 and retbleed at great cost to 2504 performance. 2505 2506config SLS 2507 bool "Mitigate Straight-Line-Speculation" 2508 depends on CC_HAS_SLS && X86_64 2509 select OBJTOOL if HAVE_OBJTOOL 2510 default n 2511 help 2512 Compile the kernel with straight-line-speculation options to guard 2513 against straight line speculation. The kernel image might be slightly 2514 larger. 2515 2516endif 2517 2518config ARCH_HAS_ADD_PAGES 2519 def_bool y 2520 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2521 2522config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2523 def_bool y 2524 2525menu "Power management and ACPI options" 2526 2527config ARCH_HIBERNATION_HEADER 2528 def_bool y 2529 depends on HIBERNATION 2530 2531source "kernel/power/Kconfig" 2532 2533source "drivers/acpi/Kconfig" 2534 2535config X86_APM_BOOT 2536 def_bool y 2537 depends on APM 2538 2539menuconfig APM 2540 tristate "APM (Advanced Power Management) BIOS support" 2541 depends on X86_32 && PM_SLEEP 2542 help 2543 APM is a BIOS specification for saving power using several different 2544 techniques. This is mostly useful for battery powered laptops with 2545 APM compliant BIOSes. If you say Y here, the system time will be 2546 reset after a RESUME operation, the /proc/apm device will provide 2547 battery status information, and user-space programs will receive 2548 notification of APM "events" (e.g. battery status change). 2549 2550 If you select "Y" here, you can disable actual use of the APM 2551 BIOS by passing the "apm=off" option to the kernel at boot time. 2552 2553 Note that the APM support is almost completely disabled for 2554 machines with more than one CPU. 2555 2556 In order to use APM, you will need supporting software. For location 2557 and more information, read <file:Documentation/power/apm-acpi.rst> 2558 and the Battery Powered Linux mini-HOWTO, available from 2559 <http://www.tldp.org/docs.html#howto>. 2560 2561 This driver does not spin down disk drives (see the hdparm(8) 2562 manpage ("man 8 hdparm") for that), and it doesn't turn off 2563 VESA-compliant "green" monitors. 2564 2565 This driver does not support the TI 4000M TravelMate and the ACER 2566 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2567 desktop machines also don't have compliant BIOSes, and this driver 2568 may cause those machines to panic during the boot phase. 2569 2570 Generally, if you don't have a battery in your machine, there isn't 2571 much point in using this driver and you should say N. If you get 2572 random kernel OOPSes or reboots that don't seem to be related to 2573 anything, try disabling/enabling this option (or disabling/enabling 2574 APM in your BIOS). 2575 2576 Some other things you should try when experiencing seemingly random, 2577 "weird" problems: 2578 2579 1) make sure that you have enough swap space and that it is 2580 enabled. 2581 2) pass the "no-hlt" option to the kernel 2582 3) switch on floating point emulation in the kernel and pass 2583 the "no387" option to the kernel 2584 4) pass the "floppy=nodma" option to the kernel 2585 5) pass the "mem=4M" option to the kernel (thereby disabling 2586 all but the first 4 MB of RAM) 2587 6) make sure that the CPU is not over clocked. 2588 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2589 8) disable the cache from your BIOS settings 2590 9) install a fan for the video card or exchange video RAM 2591 10) install a better fan for the CPU 2592 11) exchange RAM chips 2593 12) exchange the motherboard. 2594 2595 To compile this driver as a module, choose M here: the 2596 module will be called apm. 2597 2598if APM 2599 2600config APM_IGNORE_USER_SUSPEND 2601 bool "Ignore USER SUSPEND" 2602 help 2603 This option will ignore USER SUSPEND requests. On machines with a 2604 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2605 series notebooks, it is necessary to say Y because of a BIOS bug. 2606 2607config APM_DO_ENABLE 2608 bool "Enable PM at boot time" 2609 help 2610 Enable APM features at boot time. From page 36 of the APM BIOS 2611 specification: "When disabled, the APM BIOS does not automatically 2612 power manage devices, enter the Standby State, enter the Suspend 2613 State, or take power saving steps in response to CPU Idle calls." 2614 This driver will make CPU Idle calls when Linux is idle (unless this 2615 feature is turned off -- see "Do CPU IDLE calls", below). This 2616 should always save battery power, but more complicated APM features 2617 will be dependent on your BIOS implementation. You may need to turn 2618 this option off if your computer hangs at boot time when using APM 2619 support, or if it beeps continuously instead of suspending. Turn 2620 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2621 T400CDT. This is off by default since most machines do fine without 2622 this feature. 2623 2624config APM_CPU_IDLE 2625 depends on CPU_IDLE 2626 bool "Make CPU Idle calls when idle" 2627 help 2628 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2629 On some machines, this can activate improved power savings, such as 2630 a slowed CPU clock rate, when the machine is idle. These idle calls 2631 are made after the idle loop has run for some length of time (e.g., 2632 333 mS). On some machines, this will cause a hang at boot time or 2633 whenever the CPU becomes idle. (On machines with more than one CPU, 2634 this option does nothing.) 2635 2636config APM_DISPLAY_BLANK 2637 bool "Enable console blanking using APM" 2638 help 2639 Enable console blanking using the APM. Some laptops can use this to 2640 turn off the LCD backlight when the screen blanker of the Linux 2641 virtual console blanks the screen. Note that this is only used by 2642 the virtual console screen blanker, and won't turn off the backlight 2643 when using the X Window system. This also doesn't have anything to 2644 do with your VESA-compliant power-saving monitor. Further, this 2645 option doesn't work for all laptops -- it might not turn off your 2646 backlight at all, or it might print a lot of errors to the console, 2647 especially if you are using gpm. 2648 2649config APM_ALLOW_INTS 2650 bool "Allow interrupts during APM BIOS calls" 2651 help 2652 Normally we disable external interrupts while we are making calls to 2653 the APM BIOS as a measure to lessen the effects of a badly behaving 2654 BIOS implementation. The BIOS should reenable interrupts if it 2655 needs to. Unfortunately, some BIOSes do not -- especially those in 2656 many of the newer IBM Thinkpads. If you experience hangs when you 2657 suspend, try setting this to Y. Otherwise, say N. 2658 2659endif # APM 2660 2661source "drivers/cpufreq/Kconfig" 2662 2663source "drivers/cpuidle/Kconfig" 2664 2665source "drivers/idle/Kconfig" 2666 2667endmenu 2668 2669menu "Bus options (PCI etc.)" 2670 2671choice 2672 prompt "PCI access mode" 2673 depends on X86_32 && PCI 2674 default PCI_GOANY 2675 help 2676 On PCI systems, the BIOS can be used to detect the PCI devices and 2677 determine their configuration. However, some old PCI motherboards 2678 have BIOS bugs and may crash if this is done. Also, some embedded 2679 PCI-based systems don't have any BIOS at all. Linux can also try to 2680 detect the PCI hardware directly without using the BIOS. 2681 2682 With this option, you can specify how Linux should detect the 2683 PCI devices. If you choose "BIOS", the BIOS will be used, 2684 if you choose "Direct", the BIOS won't be used, and if you 2685 choose "MMConfig", then PCI Express MMCONFIG will be used. 2686 If you choose "Any", the kernel will try MMCONFIG, then the 2687 direct access method and falls back to the BIOS if that doesn't 2688 work. If unsure, go with the default, which is "Any". 2689 2690config PCI_GOBIOS 2691 bool "BIOS" 2692 2693config PCI_GOMMCONFIG 2694 bool "MMConfig" 2695 2696config PCI_GODIRECT 2697 bool "Direct" 2698 2699config PCI_GOOLPC 2700 bool "OLPC XO-1" 2701 depends on OLPC 2702 2703config PCI_GOANY 2704 bool "Any" 2705 2706endchoice 2707 2708config PCI_BIOS 2709 def_bool y 2710 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2711 2712# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2713config PCI_DIRECT 2714 def_bool y 2715 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2716 2717config PCI_MMCONFIG 2718 bool "Support mmconfig PCI config space access" if X86_64 2719 default y 2720 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2721 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2722 2723config PCI_OLPC 2724 def_bool y 2725 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2726 2727config PCI_XEN 2728 def_bool y 2729 depends on PCI && XEN 2730 2731config MMCONF_FAM10H 2732 def_bool y 2733 depends on X86_64 && PCI_MMCONFIG && ACPI 2734 2735config PCI_CNB20LE_QUIRK 2736 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2737 depends on PCI 2738 help 2739 Read the PCI windows out of the CNB20LE host bridge. This allows 2740 PCI hotplug to work on systems with the CNB20LE chipset which do 2741 not have ACPI. 2742 2743 There's no public spec for this chipset, and this functionality 2744 is known to be incomplete. 2745 2746 You should say N unless you know you need this. 2747 2748config ISA_BUS 2749 bool "ISA bus support on modern systems" if EXPERT 2750 help 2751 Expose ISA bus device drivers and options available for selection and 2752 configuration. Enable this option if your target machine has an ISA 2753 bus. ISA is an older system, displaced by PCI and newer bus 2754 architectures -- if your target machine is modern, it probably does 2755 not have an ISA bus. 2756 2757 If unsure, say N. 2758 2759# x86_64 have no ISA slots, but can have ISA-style DMA. 2760config ISA_DMA_API 2761 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2762 default y 2763 help 2764 Enables ISA-style DMA support for devices requiring such controllers. 2765 If unsure, say Y. 2766 2767if X86_32 2768 2769config ISA 2770 bool "ISA support" 2771 help 2772 Find out whether you have ISA slots on your motherboard. ISA is the 2773 name of a bus system, i.e. the way the CPU talks to the other stuff 2774 inside your box. Other bus systems are PCI, EISA, MicroChannel 2775 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2776 newer boards don't support it. If you have ISA, say Y, otherwise N. 2777 2778config SCx200 2779 tristate "NatSemi SCx200 support" 2780 help 2781 This provides basic support for National Semiconductor's 2782 (now AMD's) Geode processors. The driver probes for the 2783 PCI-IDs of several on-chip devices, so its a good dependency 2784 for other scx200_* drivers. 2785 2786 If compiled as a module, the driver is named scx200. 2787 2788config SCx200HR_TIMER 2789 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2790 depends on SCx200 2791 default y 2792 help 2793 This driver provides a clocksource built upon the on-chip 2794 27MHz high-resolution timer. Its also a workaround for 2795 NSC Geode SC-1100's buggy TSC, which loses time when the 2796 processor goes idle (as is done by the scheduler). The 2797 other workaround is idle=poll boot option. 2798 2799config OLPC 2800 bool "One Laptop Per Child support" 2801 depends on !X86_PAE 2802 select GPIOLIB 2803 select OF 2804 select OF_PROMTREE 2805 select IRQ_DOMAIN 2806 select OLPC_EC 2807 help 2808 Add support for detecting the unique features of the OLPC 2809 XO hardware. 2810 2811config OLPC_XO1_PM 2812 bool "OLPC XO-1 Power Management" 2813 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2814 help 2815 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2816 2817config OLPC_XO1_RTC 2818 bool "OLPC XO-1 Real Time Clock" 2819 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2820 help 2821 Add support for the XO-1 real time clock, which can be used as a 2822 programmable wakeup source. 2823 2824config OLPC_XO1_SCI 2825 bool "OLPC XO-1 SCI extras" 2826 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2827 depends on INPUT=y 2828 select POWER_SUPPLY 2829 help 2830 Add support for SCI-based features of the OLPC XO-1 laptop: 2831 - EC-driven system wakeups 2832 - Power button 2833 - Ebook switch 2834 - Lid switch 2835 - AC adapter status updates 2836 - Battery status updates 2837 2838config OLPC_XO15_SCI 2839 bool "OLPC XO-1.5 SCI extras" 2840 depends on OLPC && ACPI 2841 select POWER_SUPPLY 2842 help 2843 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2844 - EC-driven system wakeups 2845 - AC adapter status updates 2846 - Battery status updates 2847 2848config ALIX 2849 bool "PCEngines ALIX System Support (LED setup)" 2850 select GPIOLIB 2851 help 2852 This option enables system support for the PCEngines ALIX. 2853 At present this just sets up LEDs for GPIO control on 2854 ALIX2/3/6 boards. However, other system specific setup should 2855 get added here. 2856 2857 Note: You must still enable the drivers for GPIO and LED support 2858 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2859 2860 Note: You have to set alix.force=1 for boards with Award BIOS. 2861 2862config NET5501 2863 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2864 select GPIOLIB 2865 help 2866 This option enables system support for the Soekris Engineering net5501. 2867 2868config GEOS 2869 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2870 select GPIOLIB 2871 depends on DMI 2872 help 2873 This option enables system support for the Traverse Technologies GEOS. 2874 2875config TS5500 2876 bool "Technologic Systems TS-5500 platform support" 2877 depends on MELAN 2878 select CHECK_SIGNATURE 2879 select NEW_LEDS 2880 select LEDS_CLASS 2881 help 2882 This option enables system support for the Technologic Systems TS-5500. 2883 2884endif # X86_32 2885 2886config AMD_NB 2887 def_bool y 2888 depends on CPU_SUP_AMD && PCI 2889 2890endmenu 2891 2892menu "Binary Emulations" 2893 2894config IA32_EMULATION 2895 bool "IA32 Emulation" 2896 depends on X86_64 2897 select ARCH_WANT_OLD_COMPAT_IPC 2898 select BINFMT_ELF 2899 select COMPAT_OLD_SIGACTION 2900 help 2901 Include code to run legacy 32-bit programs under a 2902 64-bit kernel. You should likely turn this on, unless you're 2903 100% sure that you don't have any 32-bit programs left. 2904 2905config X86_X32_ABI 2906 bool "x32 ABI for 64-bit mode" 2907 depends on X86_64 2908 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2909 # compressed debug sections to x86_x32 properly: 2910 # https://github.com/ClangBuiltLinux/linux/issues/514 2911 # https://github.com/ClangBuiltLinux/linux/issues/1141 2912 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 2913 help 2914 Include code to run binaries for the x32 native 32-bit ABI 2915 for 64-bit processors. An x32 process gets access to the 2916 full 64-bit register file and wide data path while leaving 2917 pointers at 32 bits for smaller memory footprint. 2918 2919config COMPAT_32 2920 def_bool y 2921 depends on IA32_EMULATION || X86_32 2922 select HAVE_UID16 2923 select OLD_SIGSUSPEND3 2924 2925config COMPAT 2926 def_bool y 2927 depends on IA32_EMULATION || X86_X32_ABI 2928 2929config COMPAT_FOR_U64_ALIGNMENT 2930 def_bool y 2931 depends on COMPAT 2932 2933endmenu 2934 2935config HAVE_ATOMIC_IOMAP 2936 def_bool y 2937 depends on X86_32 2938 2939source "arch/x86/kvm/Kconfig" 2940 2941source "arch/x86/Kconfig.assembler" 2942