1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_USE_CMPXCHG_LOCKREF 31 select HAVE_ARCH_SOFT_DIRTY 32 select MODULES_USE_ELF_RELA 33 select NEED_DMA_MAP_STATE 34 select SWIOTLB 35 select ARCH_HAS_ELFCORE_COMPAT 36 select ZONE_DMA32 37 38config FORCE_DYNAMIC_FTRACE 39 def_bool y 40 depends on X86_32 41 depends on FUNCTION_TRACER 42 select DYNAMIC_FTRACE 43 help 44 We keep the static function tracing (!DYNAMIC_FTRACE) around 45 in order to test the non static function tracing in the 46 generic code, as other architectures still use it. But we 47 only need to keep it around for x86_64. No need to keep it 48 for x86_32. For x86_32, force DYNAMIC_FTRACE. 49# 50# Arch settings 51# 52# ( Note that options that are marked 'if X86_64' could in principle be 53# ported to 32-bit as well. ) 54# 55config X86 56 def_bool y 57 # 58 # Note: keep this list sorted alphabetically 59 # 60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 62 select ARCH_32BIT_OFF_T if X86_32 63 select ARCH_CLOCKSOURCE_INIT 64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 71 select ARCH_HAS_CACHE_LINE_SIZE 72 select ARCH_HAS_CURRENT_STACK_POINTER 73 select ARCH_HAS_DEBUG_VIRTUAL 74 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 75 select ARCH_HAS_DEVMEM_IS_ALLOWED 76 select ARCH_HAS_EARLY_DEBUG if KGDB 77 select ARCH_HAS_ELF_RANDOMIZE 78 select ARCH_HAS_FAST_MULTIPLIER 79 select ARCH_HAS_FORTIFY_SOURCE 80 select ARCH_HAS_GCOV_PROFILE_ALL 81 select ARCH_HAS_KCOV if X86_64 82 select ARCH_HAS_MEM_ENCRYPT 83 select ARCH_HAS_MEMBARRIER_SYNC_CORE 84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 85 select ARCH_HAS_PMEM_API if X86_64 86 select ARCH_HAS_PTE_DEVMAP if X86_64 87 select ARCH_HAS_PTE_SPECIAL 88 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 89 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 90 select ARCH_HAS_COPY_MC if X86_64 91 select ARCH_HAS_SET_MEMORY 92 select ARCH_HAS_SET_DIRECT_MAP 93 select ARCH_HAS_STRICT_KERNEL_RWX 94 select ARCH_HAS_STRICT_MODULE_RWX 95 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 96 select ARCH_HAS_SYSCALL_WRAPPER 97 select ARCH_HAS_UBSAN_SANITIZE_ALL 98 select ARCH_HAS_DEBUG_WX 99 select ARCH_HAS_ZONE_DMA_SET if EXPERT 100 select ARCH_HAVE_NMI_SAFE_CMPXCHG 101 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 102 select ARCH_MIGHT_HAVE_PC_PARPORT 103 select ARCH_MIGHT_HAVE_PC_SERIO 104 select ARCH_STACKWALK 105 select ARCH_SUPPORTS_ACPI 106 select ARCH_SUPPORTS_ATOMIC_RMW 107 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 108 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 109 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 110 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 111 select ARCH_SUPPORTS_CFI_CLANG if X86_64 112 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 113 select ARCH_SUPPORTS_LTO_CLANG 114 select ARCH_SUPPORTS_LTO_CLANG_THIN 115 select ARCH_USE_BUILTIN_BSWAP 116 select ARCH_USE_MEMTEST 117 select ARCH_USE_QUEUED_RWLOCKS 118 select ARCH_USE_QUEUED_SPINLOCKS 119 select ARCH_USE_SYM_ANNOTATIONS 120 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 121 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 122 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 123 select ARCH_WANTS_NO_INSTR 124 select ARCH_WANT_GENERAL_HUGETLB 125 select ARCH_WANT_HUGE_PMD_SHARE 126 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64 127 select ARCH_WANT_LD_ORPHAN_WARN 128 select ARCH_WANTS_THP_SWAP if X86_64 129 select ARCH_HAS_PARANOID_L1D_FLUSH 130 select BUILDTIME_TABLE_SORT 131 select CLKEVT_I8253 132 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 133 select CLOCKSOURCE_WATCHDOG 134 # Word-size accesses may read uninitialized data past the trailing \0 135 # in strings and cause false KMSAN reports. 136 select DCACHE_WORD_ACCESS if !KMSAN 137 select DYNAMIC_SIGFRAME 138 select EDAC_ATOMIC_SCRUB 139 select EDAC_SUPPORT 140 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 141 select GENERIC_CLOCKEVENTS_MIN_ADJUST 142 select GENERIC_CMOS_UPDATE 143 select GENERIC_CPU_AUTOPROBE 144 select GENERIC_CPU_VULNERABILITIES 145 select GENERIC_EARLY_IOREMAP 146 select GENERIC_ENTRY 147 select GENERIC_IOMAP 148 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 149 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 150 select GENERIC_IRQ_MIGRATION if SMP 151 select GENERIC_IRQ_PROBE 152 select GENERIC_IRQ_RESERVATION_MODE 153 select GENERIC_IRQ_SHOW 154 select GENERIC_PENDING_IRQ if SMP 155 select GENERIC_PTDUMP 156 select GENERIC_SMP_IDLE_THREAD 157 select GENERIC_TIME_VSYSCALL 158 select GENERIC_GETTIMEOFDAY 159 select GENERIC_VDSO_TIME_NS 160 select GUP_GET_PTE_LOW_HIGH if X86_PAE 161 select HARDIRQS_SW_RESEND 162 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 163 select HAVE_ACPI_APEI if ACPI 164 select HAVE_ACPI_APEI_NMI if ACPI 165 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 166 select HAVE_ARCH_AUDITSYSCALL 167 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 168 select HAVE_ARCH_HUGE_VMALLOC if X86_64 169 select HAVE_ARCH_JUMP_LABEL 170 select HAVE_ARCH_JUMP_LABEL_RELATIVE 171 select HAVE_ARCH_KASAN if X86_64 172 select HAVE_ARCH_KASAN_VMALLOC if X86_64 173 select HAVE_ARCH_KFENCE 174 select HAVE_ARCH_KMSAN if X86_64 175 select HAVE_ARCH_KGDB 176 select HAVE_ARCH_MMAP_RND_BITS if MMU 177 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 178 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 179 select HAVE_ARCH_PREL32_RELOCATIONS 180 select HAVE_ARCH_SECCOMP_FILTER 181 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 182 select HAVE_ARCH_STACKLEAK 183 select HAVE_ARCH_TRACEHOOK 184 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 185 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 186 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 187 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 188 select HAVE_ARCH_VMAP_STACK if X86_64 189 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 190 select HAVE_ARCH_WITHIN_STACK_FRAMES 191 select HAVE_ASM_MODVERSIONS 192 select HAVE_CMPXCHG_DOUBLE 193 select HAVE_CMPXCHG_LOCAL 194 select HAVE_CONTEXT_TRACKING_USER if X86_64 195 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 196 select HAVE_C_RECORDMCOUNT 197 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 198 select HAVE_BUILDTIME_MCOUNT_SORT 199 select HAVE_DEBUG_KMEMLEAK 200 select HAVE_DMA_CONTIGUOUS 201 select HAVE_DYNAMIC_FTRACE 202 select HAVE_DYNAMIC_FTRACE_WITH_REGS 203 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 204 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 205 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 206 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 207 select HAVE_EBPF_JIT 208 select HAVE_EFFICIENT_UNALIGNED_ACCESS 209 select HAVE_EISA 210 select HAVE_EXIT_THREAD 211 select HAVE_FAST_GUP 212 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 213 select HAVE_FTRACE_MCOUNT_RECORD 214 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 215 select HAVE_FUNCTION_TRACER 216 select HAVE_GCC_PLUGINS 217 select HAVE_HW_BREAKPOINT 218 select HAVE_IOREMAP_PROT 219 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 220 select HAVE_IRQ_TIME_ACCOUNTING 221 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 222 select HAVE_KERNEL_BZIP2 223 select HAVE_KERNEL_GZIP 224 select HAVE_KERNEL_LZ4 225 select HAVE_KERNEL_LZMA 226 select HAVE_KERNEL_LZO 227 select HAVE_KERNEL_XZ 228 select HAVE_KERNEL_ZSTD 229 select HAVE_KPROBES 230 select HAVE_KPROBES_ON_FTRACE 231 select HAVE_FUNCTION_ERROR_INJECTION 232 select HAVE_KRETPROBES 233 select HAVE_RETHOOK 234 select HAVE_KVM 235 select HAVE_LIVEPATCH if X86_64 236 select HAVE_MIXED_BREAKPOINTS_REGS 237 select HAVE_MOD_ARCH_SPECIFIC 238 select HAVE_MOVE_PMD 239 select HAVE_MOVE_PUD 240 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 241 select HAVE_NMI 242 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 243 select HAVE_OBJTOOL if X86_64 244 select HAVE_OPTPROBES 245 select HAVE_PCSPKR_PLATFORM 246 select HAVE_PERF_EVENTS 247 select HAVE_PERF_EVENTS_NMI 248 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 249 select HAVE_PCI 250 select HAVE_PERF_REGS 251 select HAVE_PERF_USER_STACK_DUMP 252 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 253 select MMU_GATHER_MERGE_VMAS 254 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 255 select HAVE_REGS_AND_STACK_ACCESS_API 256 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 257 select HAVE_FUNCTION_ARG_ACCESS_API 258 select HAVE_SETUP_PER_CPU_AREA 259 select HAVE_SOFTIRQ_ON_OWN_STACK 260 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 261 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 262 select HAVE_STATIC_CALL 263 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 264 select HAVE_PREEMPT_DYNAMIC_CALL 265 select HAVE_RSEQ 266 select HAVE_RUST if X86_64 267 select HAVE_SYSCALL_TRACEPOINTS 268 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 269 select HAVE_UNSTABLE_SCHED_CLOCK 270 select HAVE_USER_RETURN_NOTIFIER 271 select HAVE_GENERIC_VDSO 272 select HOTPLUG_SMT if SMP 273 select IRQ_FORCED_THREADING 274 select NEED_PER_CPU_EMBED_FIRST_CHUNK 275 select NEED_PER_CPU_PAGE_FIRST_CHUNK 276 select NEED_SG_DMA_LENGTH 277 select PCI_DOMAINS if PCI 278 select PCI_LOCKLESS_CONFIG if PCI 279 select PERF_EVENTS 280 select RTC_LIB 281 select RTC_MC146818_LIB 282 select SPARSE_IRQ 283 select SRCU 284 select SYSCTL_EXCEPTION_TRACE 285 select THREAD_INFO_IN_TASK 286 select TRACE_IRQFLAGS_SUPPORT 287 select TRACE_IRQFLAGS_NMI_SUPPORT 288 select USER_STACKTRACE_SUPPORT 289 select HAVE_ARCH_KCSAN if X86_64 290 select X86_FEATURE_NAMES if PROC_FS 291 select PROC_PID_ARCH_STATUS if PROC_FS 292 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 293 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 294 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 295 296config INSTRUCTION_DECODER 297 def_bool y 298 depends on KPROBES || PERF_EVENTS || UPROBES 299 300config OUTPUT_FORMAT 301 string 302 default "elf32-i386" if X86_32 303 default "elf64-x86-64" if X86_64 304 305config LOCKDEP_SUPPORT 306 def_bool y 307 308config STACKTRACE_SUPPORT 309 def_bool y 310 311config MMU 312 def_bool y 313 314config ARCH_MMAP_RND_BITS_MIN 315 default 28 if 64BIT 316 default 8 317 318config ARCH_MMAP_RND_BITS_MAX 319 default 32 if 64BIT 320 default 16 321 322config ARCH_MMAP_RND_COMPAT_BITS_MIN 323 default 8 324 325config ARCH_MMAP_RND_COMPAT_BITS_MAX 326 default 16 327 328config SBUS 329 bool 330 331config GENERIC_ISA_DMA 332 def_bool y 333 depends on ISA_DMA_API 334 335config GENERIC_CSUM 336 bool 337 default y if KMSAN || KASAN 338 339config GENERIC_BUG 340 def_bool y 341 depends on BUG 342 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 343 344config GENERIC_BUG_RELATIVE_POINTERS 345 bool 346 347config ARCH_MAY_HAVE_PC_FDC 348 def_bool y 349 depends on ISA_DMA_API 350 351config GENERIC_CALIBRATE_DELAY 352 def_bool y 353 354config ARCH_HAS_CPU_RELAX 355 def_bool y 356 357config ARCH_HIBERNATION_POSSIBLE 358 def_bool y 359 360config ARCH_NR_GPIO 361 int 362 default 1024 if X86_64 363 default 512 364 365config ARCH_SUSPEND_POSSIBLE 366 def_bool y 367 368config AUDIT_ARCH 369 def_bool y if X86_64 370 371config KASAN_SHADOW_OFFSET 372 hex 373 depends on KASAN 374 default 0xdffffc0000000000 375 376config HAVE_INTEL_TXT 377 def_bool y 378 depends on INTEL_IOMMU && ACPI 379 380config X86_32_SMP 381 def_bool y 382 depends on X86_32 && SMP 383 384config X86_64_SMP 385 def_bool y 386 depends on X86_64 && SMP 387 388config ARCH_SUPPORTS_UPROBES 389 def_bool y 390 391config FIX_EARLYCON_MEM 392 def_bool y 393 394config DYNAMIC_PHYSICAL_MASK 395 bool 396 397config PGTABLE_LEVELS 398 int 399 default 5 if X86_5LEVEL 400 default 4 if X86_64 401 default 3 if X86_PAE 402 default 2 403 404config CC_HAS_SANE_STACKPROTECTOR 405 bool 406 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 407 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 408 help 409 We have to make sure stack protector is unconditionally disabled if 410 the compiler produces broken code or if it does not let us control 411 the segment on 32-bit kernels. 412 413menu "Processor type and features" 414 415config SMP 416 bool "Symmetric multi-processing support" 417 help 418 This enables support for systems with more than one CPU. If you have 419 a system with only one CPU, say N. If you have a system with more 420 than one CPU, say Y. 421 422 If you say N here, the kernel will run on uni- and multiprocessor 423 machines, but will use only one CPU of a multiprocessor machine. If 424 you say Y here, the kernel will run on many, but not all, 425 uniprocessor machines. On a uniprocessor machine, the kernel 426 will run faster if you say N here. 427 428 Note that if you say Y here and choose architecture "586" or 429 "Pentium" under "Processor family", the kernel will not work on 486 430 architectures. Similarly, multiprocessor kernels for the "PPro" 431 architecture may not work on all Pentium based boards. 432 433 People using multiprocessor machines who say Y here should also say 434 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 435 Management" code will be disabled if you say Y here. 436 437 See also <file:Documentation/x86/i386/IO-APIC.rst>, 438 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 439 <http://www.tldp.org/docs.html#howto>. 440 441 If you don't know what to do here, say N. 442 443config X86_FEATURE_NAMES 444 bool "Processor feature human-readable names" if EMBEDDED 445 default y 446 help 447 This option compiles in a table of x86 feature bits and corresponding 448 names. This is required to support /proc/cpuinfo and a few kernel 449 messages. You can disable this to save space, at the expense of 450 making those few kernel messages show numeric feature bits instead. 451 452 If in doubt, say Y. 453 454config X86_X2APIC 455 bool "Support x2apic" 456 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 457 help 458 This enables x2apic support on CPUs that have this feature. 459 460 This allows 32-bit apic IDs (so it can support very large systems), 461 and accesses the local apic via MSRs not via mmio. 462 463 Some Intel systems circa 2022 and later are locked into x2APIC mode 464 and can not fall back to the legacy APIC modes if SGX or TDX are 465 enabled in the BIOS. They will be unable to boot without enabling 466 this option. 467 468 If you don't know what to do here, say N. 469 470config X86_MPPARSE 471 bool "Enable MPS table" if ACPI 472 default y 473 depends on X86_LOCAL_APIC 474 help 475 For old smp systems that do not have proper acpi support. Newer systems 476 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 477 478config GOLDFISH 479 def_bool y 480 depends on X86_GOLDFISH 481 482config X86_CPU_RESCTRL 483 bool "x86 CPU resource control support" 484 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 485 select KERNFS 486 select PROC_CPU_RESCTRL if PROC_FS 487 help 488 Enable x86 CPU resource control support. 489 490 Provide support for the allocation and monitoring of system resources 491 usage by the CPU. 492 493 Intel calls this Intel Resource Director Technology 494 (Intel(R) RDT). More information about RDT can be found in the 495 Intel x86 Architecture Software Developer Manual. 496 497 AMD calls this AMD Platform Quality of Service (AMD QoS). 498 More information about AMD QoS can be found in the AMD64 Technology 499 Platform Quality of Service Extensions manual. 500 501 Say N if unsure. 502 503if X86_32 504config X86_BIGSMP 505 bool "Support for big SMP systems with more than 8 CPUs" 506 depends on SMP 507 help 508 This option is needed for the systems that have more than 8 CPUs. 509 510config X86_EXTENDED_PLATFORM 511 bool "Support for extended (non-PC) x86 platforms" 512 default y 513 help 514 If you disable this option then the kernel will only support 515 standard PC platforms. (which covers the vast majority of 516 systems out there.) 517 518 If you enable this option then you'll be able to select support 519 for the following (non-PC) 32 bit x86 platforms: 520 Goldfish (Android emulator) 521 AMD Elan 522 RDC R-321x SoC 523 SGI 320/540 (Visual Workstation) 524 STA2X11-based (e.g. Northville) 525 Moorestown MID devices 526 527 If you have one of these systems, or if you want to build a 528 generic distribution kernel, say Y here - otherwise say N. 529endif # X86_32 530 531if X86_64 532config X86_EXTENDED_PLATFORM 533 bool "Support for extended (non-PC) x86 platforms" 534 default y 535 help 536 If you disable this option then the kernel will only support 537 standard PC platforms. (which covers the vast majority of 538 systems out there.) 539 540 If you enable this option then you'll be able to select support 541 for the following (non-PC) 64 bit x86 platforms: 542 Numascale NumaChip 543 ScaleMP vSMP 544 SGI Ultraviolet 545 546 If you have one of these systems, or if you want to build a 547 generic distribution kernel, say Y here - otherwise say N. 548endif # X86_64 549# This is an alphabetically sorted list of 64 bit extended platforms 550# Please maintain the alphabetic order if and when there are additions 551config X86_NUMACHIP 552 bool "Numascale NumaChip" 553 depends on X86_64 554 depends on X86_EXTENDED_PLATFORM 555 depends on NUMA 556 depends on SMP 557 depends on X86_X2APIC 558 depends on PCI_MMCONFIG 559 help 560 Adds support for Numascale NumaChip large-SMP systems. Needed to 561 enable more than ~168 cores. 562 If you don't have one of these, you should say N here. 563 564config X86_VSMP 565 bool "ScaleMP vSMP" 566 select HYPERVISOR_GUEST 567 select PARAVIRT 568 depends on X86_64 && PCI 569 depends on X86_EXTENDED_PLATFORM 570 depends on SMP 571 help 572 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 573 supposed to run on these EM64T-based machines. Only choose this option 574 if you have one of these machines. 575 576config X86_UV 577 bool "SGI Ultraviolet" 578 depends on X86_64 579 depends on X86_EXTENDED_PLATFORM 580 depends on NUMA 581 depends on EFI 582 depends on KEXEC_CORE 583 depends on X86_X2APIC 584 depends on PCI 585 help 586 This option is needed in order to support SGI Ultraviolet systems. 587 If you don't have one of these, you should say N here. 588 589# Following is an alphabetically sorted list of 32 bit extended platforms 590# Please maintain the alphabetic order if and when there are additions 591 592config X86_GOLDFISH 593 bool "Goldfish (Virtual Platform)" 594 depends on X86_EXTENDED_PLATFORM 595 help 596 Enable support for the Goldfish virtual platform used primarily 597 for Android development. Unless you are building for the Android 598 Goldfish emulator say N here. 599 600config X86_INTEL_CE 601 bool "CE4100 TV platform" 602 depends on PCI 603 depends on PCI_GODIRECT 604 depends on X86_IO_APIC 605 depends on X86_32 606 depends on X86_EXTENDED_PLATFORM 607 select X86_REBOOTFIXUPS 608 select OF 609 select OF_EARLY_FLATTREE 610 help 611 Select for the Intel CE media processor (CE4100) SOC. 612 This option compiles in support for the CE4100 SOC for settop 613 boxes and media devices. 614 615config X86_INTEL_MID 616 bool "Intel MID platform support" 617 depends on X86_EXTENDED_PLATFORM 618 depends on X86_PLATFORM_DEVICES 619 depends on PCI 620 depends on X86_64 || (PCI_GOANY && X86_32) 621 depends on X86_IO_APIC 622 select I2C 623 select DW_APB_TIMER 624 select INTEL_SCU_PCI 625 help 626 Select to build a kernel capable of supporting Intel MID (Mobile 627 Internet Device) platform systems which do not have the PCI legacy 628 interfaces. If you are building for a PC class system say N here. 629 630 Intel MID platforms are based on an Intel processor and chipset which 631 consume less power than most of the x86 derivatives. 632 633config X86_INTEL_QUARK 634 bool "Intel Quark platform support" 635 depends on X86_32 636 depends on X86_EXTENDED_PLATFORM 637 depends on X86_PLATFORM_DEVICES 638 depends on X86_TSC 639 depends on PCI 640 depends on PCI_GOANY 641 depends on X86_IO_APIC 642 select IOSF_MBI 643 select INTEL_IMR 644 select COMMON_CLK 645 help 646 Select to include support for Quark X1000 SoC. 647 Say Y here if you have a Quark based system such as the Arduino 648 compatible Intel Galileo. 649 650config X86_INTEL_LPSS 651 bool "Intel Low Power Subsystem Support" 652 depends on X86 && ACPI && PCI 653 select COMMON_CLK 654 select PINCTRL 655 select IOSF_MBI 656 help 657 Select to build support for Intel Low Power Subsystem such as 658 found on Intel Lynxpoint PCH. Selecting this option enables 659 things like clock tree (common clock framework) and pincontrol 660 which are needed by the LPSS peripheral drivers. 661 662config X86_AMD_PLATFORM_DEVICE 663 bool "AMD ACPI2Platform devices support" 664 depends on ACPI 665 select COMMON_CLK 666 select PINCTRL 667 help 668 Select to interpret AMD specific ACPI device to platform device 669 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 670 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 671 implemented under PINCTRL subsystem. 672 673config IOSF_MBI 674 tristate "Intel SoC IOSF Sideband support for SoC platforms" 675 depends on PCI 676 help 677 This option enables sideband register access support for Intel SoC 678 platforms. On these platforms the IOSF sideband is used in lieu of 679 MSR's for some register accesses, mostly but not limited to thermal 680 and power. Drivers may query the availability of this device to 681 determine if they need the sideband in order to work on these 682 platforms. The sideband is available on the following SoC products. 683 This list is not meant to be exclusive. 684 - BayTrail 685 - Braswell 686 - Quark 687 688 You should say Y if you are running a kernel on one of these SoC's. 689 690config IOSF_MBI_DEBUG 691 bool "Enable IOSF sideband access through debugfs" 692 depends on IOSF_MBI && DEBUG_FS 693 help 694 Select this option to expose the IOSF sideband access registers (MCR, 695 MDR, MCRX) through debugfs to write and read register information from 696 different units on the SoC. This is most useful for obtaining device 697 state information for debug and analysis. As this is a general access 698 mechanism, users of this option would have specific knowledge of the 699 device they want to access. 700 701 If you don't require the option or are in doubt, say N. 702 703config X86_RDC321X 704 bool "RDC R-321x SoC" 705 depends on X86_32 706 depends on X86_EXTENDED_PLATFORM 707 select M486 708 select X86_REBOOTFIXUPS 709 help 710 This option is needed for RDC R-321x system-on-chip, also known 711 as R-8610-(G). 712 If you don't have one of these chips, you should say N here. 713 714config X86_32_NON_STANDARD 715 bool "Support non-standard 32-bit SMP architectures" 716 depends on X86_32 && SMP 717 depends on X86_EXTENDED_PLATFORM 718 help 719 This option compiles in the bigsmp and STA2X11 default 720 subarchitectures. It is intended for a generic binary 721 kernel. If you select them all, kernel will probe it one by 722 one and will fallback to default. 723 724# Alphabetically sorted list of Non standard 32 bit platforms 725 726config X86_SUPPORTS_MEMORY_FAILURE 727 def_bool y 728 # MCE code calls memory_failure(): 729 depends on X86_MCE 730 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 731 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 732 depends on X86_64 || !SPARSEMEM 733 select ARCH_SUPPORTS_MEMORY_FAILURE 734 735config STA2X11 736 bool "STA2X11 Companion Chip Support" 737 depends on X86_32_NON_STANDARD && PCI 738 select SWIOTLB 739 select MFD_STA2X11 740 select GPIOLIB 741 help 742 This adds support for boards based on the STA2X11 IO-Hub, 743 a.k.a. "ConneXt". The chip is used in place of the standard 744 PC chipset, so all "standard" peripherals are missing. If this 745 option is selected the kernel will still be able to boot on 746 standard PC machines. 747 748config X86_32_IRIS 749 tristate "Eurobraille/Iris poweroff module" 750 depends on X86_32 751 help 752 The Iris machines from EuroBraille do not have APM or ACPI support 753 to shut themselves down properly. A special I/O sequence is 754 needed to do so, which is what this module does at 755 kernel shutdown. 756 757 This is only for Iris machines from EuroBraille. 758 759 If unused, say N. 760 761config SCHED_OMIT_FRAME_POINTER 762 def_bool y 763 prompt "Single-depth WCHAN output" 764 depends on X86 765 help 766 Calculate simpler /proc/<PID>/wchan values. If this option 767 is disabled then wchan values will recurse back to the 768 caller function. This provides more accurate wchan values, 769 at the expense of slightly more scheduling overhead. 770 771 If in doubt, say "Y". 772 773menuconfig HYPERVISOR_GUEST 774 bool "Linux guest support" 775 help 776 Say Y here to enable options for running Linux under various hyper- 777 visors. This option enables basic hypervisor detection and platform 778 setup. 779 780 If you say N, all options in this submenu will be skipped and 781 disabled, and Linux guest support won't be built in. 782 783if HYPERVISOR_GUEST 784 785config PARAVIRT 786 bool "Enable paravirtualization code" 787 depends on HAVE_STATIC_CALL 788 help 789 This changes the kernel so it can modify itself when it is run 790 under a hypervisor, potentially improving performance significantly 791 over full virtualization. However, when run without a hypervisor 792 the kernel is theoretically slower and slightly larger. 793 794config PARAVIRT_XXL 795 bool 796 797config PARAVIRT_DEBUG 798 bool "paravirt-ops debugging" 799 depends on PARAVIRT && DEBUG_KERNEL 800 help 801 Enable to debug paravirt_ops internals. Specifically, BUG if 802 a paravirt_op is missing when it is called. 803 804config PARAVIRT_SPINLOCKS 805 bool "Paravirtualization layer for spinlocks" 806 depends on PARAVIRT && SMP 807 help 808 Paravirtualized spinlocks allow a pvops backend to replace the 809 spinlock implementation with something virtualization-friendly 810 (for example, block the virtual CPU rather than spinning). 811 812 It has a minimal impact on native kernels and gives a nice performance 813 benefit on paravirtualized KVM / Xen kernels. 814 815 If you are unsure how to answer this question, answer Y. 816 817config X86_HV_CALLBACK_VECTOR 818 def_bool n 819 820source "arch/x86/xen/Kconfig" 821 822config KVM_GUEST 823 bool "KVM Guest support (including kvmclock)" 824 depends on PARAVIRT 825 select PARAVIRT_CLOCK 826 select ARCH_CPUIDLE_HALTPOLL 827 select X86_HV_CALLBACK_VECTOR 828 default y 829 help 830 This option enables various optimizations for running under the KVM 831 hypervisor. It includes a paravirtualized clock, so that instead 832 of relying on a PIT (or probably other) emulation by the 833 underlying device model, the host provides the guest with 834 timing infrastructure such as time of day, and system time 835 836config ARCH_CPUIDLE_HALTPOLL 837 def_bool n 838 prompt "Disable host haltpoll when loading haltpoll driver" 839 help 840 If virtualized under KVM, disable host haltpoll. 841 842config PVH 843 bool "Support for running PVH guests" 844 help 845 This option enables the PVH entry point for guest virtual machines 846 as specified in the x86/HVM direct boot ABI. 847 848config PARAVIRT_TIME_ACCOUNTING 849 bool "Paravirtual steal time accounting" 850 depends on PARAVIRT 851 help 852 Select this option to enable fine granularity task steal time 853 accounting. Time spent executing other tasks in parallel with 854 the current vCPU is discounted from the vCPU power. To account for 855 that, there can be a small performance impact. 856 857 If in doubt, say N here. 858 859config PARAVIRT_CLOCK 860 bool 861 862config JAILHOUSE_GUEST 863 bool "Jailhouse non-root cell support" 864 depends on X86_64 && PCI 865 select X86_PM_TIMER 866 help 867 This option allows to run Linux as guest in a Jailhouse non-root 868 cell. You can leave this option disabled if you only want to start 869 Jailhouse and run Linux afterwards in the root cell. 870 871config ACRN_GUEST 872 bool "ACRN Guest support" 873 depends on X86_64 874 select X86_HV_CALLBACK_VECTOR 875 help 876 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 877 a flexible, lightweight reference open-source hypervisor, built with 878 real-time and safety-criticality in mind. It is built for embedded 879 IOT with small footprint and real-time features. More details can be 880 found in https://projectacrn.org/. 881 882config INTEL_TDX_GUEST 883 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 884 depends on X86_64 && CPU_SUP_INTEL 885 depends on X86_X2APIC 886 select ARCH_HAS_CC_PLATFORM 887 select X86_MEM_ENCRYPT 888 select X86_MCE 889 help 890 Support running as a guest under Intel TDX. Without this support, 891 the guest kernel can not boot or run under TDX. 892 TDX includes memory encryption and integrity capabilities 893 which protect the confidentiality and integrity of guest 894 memory contents and CPU state. TDX guests are protected from 895 some attacks from the VMM. 896 897endif # HYPERVISOR_GUEST 898 899source "arch/x86/Kconfig.cpu" 900 901config HPET_TIMER 902 def_bool X86_64 903 prompt "HPET Timer Support" if X86_32 904 help 905 Use the IA-PC HPET (High Precision Event Timer) to manage 906 time in preference to the PIT and RTC, if a HPET is 907 present. 908 HPET is the next generation timer replacing legacy 8254s. 909 The HPET provides a stable time base on SMP 910 systems, unlike the TSC, but it is more expensive to access, 911 as it is off-chip. The interface used is documented 912 in the HPET spec, revision 1. 913 914 You can safely choose Y here. However, HPET will only be 915 activated if the platform and the BIOS support this feature. 916 Otherwise the 8254 will be used for timing services. 917 918 Choose N to continue using the legacy 8254 timer. 919 920config HPET_EMULATE_RTC 921 def_bool y 922 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 923 924# Mark as expert because too many people got it wrong. 925# The code disables itself when not needed. 926config DMI 927 default y 928 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 929 bool "Enable DMI scanning" if EXPERT 930 help 931 Enabled scanning of DMI to identify machine quirks. Say Y 932 here unless you have verified that your setup is not 933 affected by entries in the DMI blacklist. Required by PNP 934 BIOS code. 935 936config GART_IOMMU 937 bool "Old AMD GART IOMMU support" 938 select DMA_OPS 939 select IOMMU_HELPER 940 select SWIOTLB 941 depends on X86_64 && PCI && AMD_NB 942 help 943 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 944 GART based hardware IOMMUs. 945 946 The GART supports full DMA access for devices with 32-bit access 947 limitations, on systems with more than 3 GB. This is usually needed 948 for USB, sound, many IDE/SATA chipsets and some other devices. 949 950 Newer systems typically have a modern AMD IOMMU, supported via 951 the CONFIG_AMD_IOMMU=y config option. 952 953 In normal configurations this driver is only active when needed: 954 there's more than 3 GB of memory and the system contains a 955 32-bit limited device. 956 957 If unsure, say Y. 958 959config BOOT_VESA_SUPPORT 960 bool 961 help 962 If true, at least one selected framebuffer driver can take advantage 963 of VESA video modes set at an early boot stage via the vga= parameter. 964 965config MAXSMP 966 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 967 depends on X86_64 && SMP && DEBUG_KERNEL 968 select CPUMASK_OFFSTACK 969 help 970 Enable maximum number of CPUS and NUMA Nodes for this architecture. 971 If unsure, say N. 972 973# 974# The maximum number of CPUs supported: 975# 976# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 977# and which can be configured interactively in the 978# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 979# 980# The ranges are different on 32-bit and 64-bit kernels, depending on 981# hardware capabilities and scalability features of the kernel. 982# 983# ( If MAXSMP is enabled we just use the highest possible value and disable 984# interactive configuration. ) 985# 986 987config NR_CPUS_RANGE_BEGIN 988 int 989 default NR_CPUS_RANGE_END if MAXSMP 990 default 1 if !SMP 991 default 2 992 993config NR_CPUS_RANGE_END 994 int 995 depends on X86_32 996 default 64 if SMP && X86_BIGSMP 997 default 8 if SMP && !X86_BIGSMP 998 default 1 if !SMP 999 1000config NR_CPUS_RANGE_END 1001 int 1002 depends on X86_64 1003 default 8192 if SMP && CPUMASK_OFFSTACK 1004 default 512 if SMP && !CPUMASK_OFFSTACK 1005 default 1 if !SMP 1006 1007config NR_CPUS_DEFAULT 1008 int 1009 depends on X86_32 1010 default 32 if X86_BIGSMP 1011 default 8 if SMP 1012 default 1 if !SMP 1013 1014config NR_CPUS_DEFAULT 1015 int 1016 depends on X86_64 1017 default 8192 if MAXSMP 1018 default 64 if SMP 1019 default 1 if !SMP 1020 1021config NR_CPUS 1022 int "Maximum number of CPUs" if SMP && !MAXSMP 1023 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1024 default NR_CPUS_DEFAULT 1025 help 1026 This allows you to specify the maximum number of CPUs which this 1027 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1028 supported value is 8192, otherwise the maximum value is 512. The 1029 minimum value which makes sense is 2. 1030 1031 This is purely to save memory: each supported CPU adds about 8KB 1032 to the kernel image. 1033 1034config SCHED_CLUSTER 1035 bool "Cluster scheduler support" 1036 depends on SMP 1037 default y 1038 help 1039 Cluster scheduler support improves the CPU scheduler's decision 1040 making when dealing with machines that have clusters of CPUs. 1041 Cluster usually means a couple of CPUs which are placed closely 1042 by sharing mid-level caches, last-level cache tags or internal 1043 busses. 1044 1045config SCHED_SMT 1046 def_bool y if SMP 1047 1048config SCHED_MC 1049 def_bool y 1050 prompt "Multi-core scheduler support" 1051 depends on SMP 1052 help 1053 Multi-core scheduler support improves the CPU scheduler's decision 1054 making when dealing with multi-core CPU chips at a cost of slightly 1055 increased overhead in some places. If unsure say N here. 1056 1057config SCHED_MC_PRIO 1058 bool "CPU core priorities scheduler support" 1059 depends on SCHED_MC && CPU_SUP_INTEL 1060 select X86_INTEL_PSTATE 1061 select CPU_FREQ 1062 default y 1063 help 1064 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1065 core ordering determined at manufacturing time, which allows 1066 certain cores to reach higher turbo frequencies (when running 1067 single threaded workloads) than others. 1068 1069 Enabling this kernel feature teaches the scheduler about 1070 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1071 scheduler's CPU selection logic accordingly, so that higher 1072 overall system performance can be achieved. 1073 1074 This feature will have no effect on CPUs without this feature. 1075 1076 If unsure say Y here. 1077 1078config UP_LATE_INIT 1079 def_bool y 1080 depends on !SMP && X86_LOCAL_APIC 1081 1082config X86_UP_APIC 1083 bool "Local APIC support on uniprocessors" if !PCI_MSI 1084 default PCI_MSI 1085 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1086 help 1087 A local APIC (Advanced Programmable Interrupt Controller) is an 1088 integrated interrupt controller in the CPU. If you have a single-CPU 1089 system which has a processor with a local APIC, you can say Y here to 1090 enable and use it. If you say Y here even though your machine doesn't 1091 have a local APIC, then the kernel will still run with no slowdown at 1092 all. The local APIC supports CPU-generated self-interrupts (timer, 1093 performance counters), and the NMI watchdog which detects hard 1094 lockups. 1095 1096config X86_UP_IOAPIC 1097 bool "IO-APIC support on uniprocessors" 1098 depends on X86_UP_APIC 1099 help 1100 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1101 SMP-capable replacement for PC-style interrupt controllers. Most 1102 SMP systems and many recent uniprocessor systems have one. 1103 1104 If you have a single-CPU system with an IO-APIC, you can say Y here 1105 to use it. If you say Y here even though your machine doesn't have 1106 an IO-APIC, then the kernel will still run with no slowdown at all. 1107 1108config X86_LOCAL_APIC 1109 def_bool y 1110 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1111 select IRQ_DOMAIN_HIERARCHY 1112 select PCI_MSI_IRQ_DOMAIN if PCI_MSI 1113 1114config X86_IO_APIC 1115 def_bool y 1116 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1117 1118config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1119 bool "Reroute for broken boot IRQs" 1120 depends on X86_IO_APIC 1121 help 1122 This option enables a workaround that fixes a source of 1123 spurious interrupts. This is recommended when threaded 1124 interrupt handling is used on systems where the generation of 1125 superfluous "boot interrupts" cannot be disabled. 1126 1127 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1128 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1129 kernel does during interrupt handling). On chipsets where this 1130 boot IRQ generation cannot be disabled, this workaround keeps 1131 the original IRQ line masked so that only the equivalent "boot 1132 IRQ" is delivered to the CPUs. The workaround also tells the 1133 kernel to set up the IRQ handler on the boot IRQ line. In this 1134 way only one interrupt is delivered to the kernel. Otherwise 1135 the spurious second interrupt may cause the kernel to bring 1136 down (vital) interrupt lines. 1137 1138 Only affects "broken" chipsets. Interrupt sharing may be 1139 increased on these systems. 1140 1141config X86_MCE 1142 bool "Machine Check / overheating reporting" 1143 select GENERIC_ALLOCATOR 1144 default y 1145 help 1146 Machine Check support allows the processor to notify the 1147 kernel if it detects a problem (e.g. overheating, data corruption). 1148 The action the kernel takes depends on the severity of the problem, 1149 ranging from warning messages to halting the machine. 1150 1151config X86_MCELOG_LEGACY 1152 bool "Support for deprecated /dev/mcelog character device" 1153 depends on X86_MCE 1154 help 1155 Enable support for /dev/mcelog which is needed by the old mcelog 1156 userspace logging daemon. Consider switching to the new generation 1157 rasdaemon solution. 1158 1159config X86_MCE_INTEL 1160 def_bool y 1161 prompt "Intel MCE features" 1162 depends on X86_MCE && X86_LOCAL_APIC 1163 help 1164 Additional support for intel specific MCE features such as 1165 the thermal monitor. 1166 1167config X86_MCE_AMD 1168 def_bool y 1169 prompt "AMD MCE features" 1170 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1171 help 1172 Additional support for AMD specific MCE features such as 1173 the DRAM Error Threshold. 1174 1175config X86_ANCIENT_MCE 1176 bool "Support for old Pentium 5 / WinChip machine checks" 1177 depends on X86_32 && X86_MCE 1178 help 1179 Include support for machine check handling on old Pentium 5 or WinChip 1180 systems. These typically need to be enabled explicitly on the command 1181 line. 1182 1183config X86_MCE_THRESHOLD 1184 depends on X86_MCE_AMD || X86_MCE_INTEL 1185 def_bool y 1186 1187config X86_MCE_INJECT 1188 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1189 tristate "Machine check injector support" 1190 help 1191 Provide support for injecting machine checks for testing purposes. 1192 If you don't know what a machine check is and you don't do kernel 1193 QA it is safe to say n. 1194 1195source "arch/x86/events/Kconfig" 1196 1197config X86_LEGACY_VM86 1198 bool "Legacy VM86 support" 1199 depends on X86_32 1200 help 1201 This option allows user programs to put the CPU into V8086 1202 mode, which is an 80286-era approximation of 16-bit real mode. 1203 1204 Some very old versions of X and/or vbetool require this option 1205 for user mode setting. Similarly, DOSEMU will use it if 1206 available to accelerate real mode DOS programs. However, any 1207 recent version of DOSEMU, X, or vbetool should be fully 1208 functional even without kernel VM86 support, as they will all 1209 fall back to software emulation. Nevertheless, if you are using 1210 a 16-bit DOS program where 16-bit performance matters, vm86 1211 mode might be faster than emulation and you might want to 1212 enable this option. 1213 1214 Note that any app that works on a 64-bit kernel is unlikely to 1215 need this option, as 64-bit kernels don't, and can't, support 1216 V8086 mode. This option is also unrelated to 16-bit protected 1217 mode and is not needed to run most 16-bit programs under Wine. 1218 1219 Enabling this option increases the complexity of the kernel 1220 and slows down exception handling a tiny bit. 1221 1222 If unsure, say N here. 1223 1224config VM86 1225 bool 1226 default X86_LEGACY_VM86 1227 1228config X86_16BIT 1229 bool "Enable support for 16-bit segments" if EXPERT 1230 default y 1231 depends on MODIFY_LDT_SYSCALL 1232 help 1233 This option is required by programs like Wine to run 16-bit 1234 protected mode legacy code on x86 processors. Disabling 1235 this option saves about 300 bytes on i386, or around 6K text 1236 plus 16K runtime memory on x86-64, 1237 1238config X86_ESPFIX32 1239 def_bool y 1240 depends on X86_16BIT && X86_32 1241 1242config X86_ESPFIX64 1243 def_bool y 1244 depends on X86_16BIT && X86_64 1245 1246config X86_VSYSCALL_EMULATION 1247 bool "Enable vsyscall emulation" if EXPERT 1248 default y 1249 depends on X86_64 1250 help 1251 This enables emulation of the legacy vsyscall page. Disabling 1252 it is roughly equivalent to booting with vsyscall=none, except 1253 that it will also disable the helpful warning if a program 1254 tries to use a vsyscall. With this option set to N, offending 1255 programs will just segfault, citing addresses of the form 1256 0xffffffffff600?00. 1257 1258 This option is required by many programs built before 2013, and 1259 care should be used even with newer programs if set to N. 1260 1261 Disabling this option saves about 7K of kernel size and 1262 possibly 4K of additional runtime pagetable memory. 1263 1264config X86_IOPL_IOPERM 1265 bool "IOPERM and IOPL Emulation" 1266 default y 1267 help 1268 This enables the ioperm() and iopl() syscalls which are necessary 1269 for legacy applications. 1270 1271 Legacy IOPL support is an overbroad mechanism which allows user 1272 space aside of accessing all 65536 I/O ports also to disable 1273 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1274 capabilities and permission from potentially active security 1275 modules. 1276 1277 The emulation restricts the functionality of the syscall to 1278 only allowing the full range I/O port access, but prevents the 1279 ability to disable interrupts from user space which would be 1280 granted if the hardware IOPL mechanism would be used. 1281 1282config TOSHIBA 1283 tristate "Toshiba Laptop support" 1284 depends on X86_32 1285 help 1286 This adds a driver to safely access the System Management Mode of 1287 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1288 not work on models with a Phoenix BIOS. The System Management Mode 1289 is used to set the BIOS and power saving options on Toshiba portables. 1290 1291 For information on utilities to make use of this driver see the 1292 Toshiba Linux utilities web site at: 1293 <http://www.buzzard.org.uk/toshiba/>. 1294 1295 Say Y if you intend to run this kernel on a Toshiba portable. 1296 Say N otherwise. 1297 1298config X86_REBOOTFIXUPS 1299 bool "Enable X86 board specific fixups for reboot" 1300 depends on X86_32 1301 help 1302 This enables chipset and/or board specific fixups to be done 1303 in order to get reboot to work correctly. This is only needed on 1304 some combinations of hardware and BIOS. The symptom, for which 1305 this config is intended, is when reboot ends with a stalled/hung 1306 system. 1307 1308 Currently, the only fixup is for the Geode machines using 1309 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1310 1311 Say Y if you want to enable the fixup. Currently, it's safe to 1312 enable this option even if you don't need it. 1313 Say N otherwise. 1314 1315config MICROCODE 1316 bool "CPU microcode loading support" 1317 default y 1318 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1319 help 1320 If you say Y here, you will be able to update the microcode on 1321 Intel and AMD processors. The Intel support is for the IA32 family, 1322 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1323 AMD support is for families 0x10 and later. You will obviously need 1324 the actual microcode binary data itself which is not shipped with 1325 the Linux kernel. 1326 1327 The preferred method to load microcode from a detached initrd is described 1328 in Documentation/x86/microcode.rst. For that you need to enable 1329 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1330 initrd for microcode blobs. 1331 1332 In addition, you can build the microcode into the kernel. For that you 1333 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1334 config option. 1335 1336config MICROCODE_INTEL 1337 bool "Intel microcode loading support" 1338 depends on CPU_SUP_INTEL && MICROCODE 1339 default MICROCODE 1340 help 1341 This options enables microcode patch loading support for Intel 1342 processors. 1343 1344 For the current Intel microcode data package go to 1345 <https://downloadcenter.intel.com> and search for 1346 'Linux Processor Microcode Data File'. 1347 1348config MICROCODE_AMD 1349 bool "AMD microcode loading support" 1350 depends on CPU_SUP_AMD && MICROCODE 1351 help 1352 If you select this option, microcode patch loading support for AMD 1353 processors will be enabled. 1354 1355config MICROCODE_LATE_LOADING 1356 bool "Late microcode loading (DANGEROUS)" 1357 default n 1358 depends on MICROCODE 1359 help 1360 Loading microcode late, when the system is up and executing instructions 1361 is a tricky business and should be avoided if possible. Just the sequence 1362 of synchronizing all cores and SMT threads is one fragile dance which does 1363 not guarantee that cores might not softlock after the loading. Therefore, 1364 use this at your own risk. Late loading taints the kernel too. 1365 1366config X86_MSR 1367 tristate "/dev/cpu/*/msr - Model-specific register support" 1368 help 1369 This device gives privileged processes access to the x86 1370 Model-Specific Registers (MSRs). It is a character device with 1371 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1372 MSR accesses are directed to a specific CPU on multi-processor 1373 systems. 1374 1375config X86_CPUID 1376 tristate "/dev/cpu/*/cpuid - CPU information support" 1377 help 1378 This device gives processes access to the x86 CPUID instruction to 1379 be executed on a specific processor. It is a character device 1380 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1381 /dev/cpu/31/cpuid. 1382 1383choice 1384 prompt "High Memory Support" 1385 default HIGHMEM4G 1386 depends on X86_32 1387 1388config NOHIGHMEM 1389 bool "off" 1390 help 1391 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1392 However, the address space of 32-bit x86 processors is only 4 1393 Gigabytes large. That means that, if you have a large amount of 1394 physical memory, not all of it can be "permanently mapped" by the 1395 kernel. The physical memory that's not permanently mapped is called 1396 "high memory". 1397 1398 If you are compiling a kernel which will never run on a machine with 1399 more than 1 Gigabyte total physical RAM, answer "off" here (default 1400 choice and suitable for most users). This will result in a "3GB/1GB" 1401 split: 3GB are mapped so that each process sees a 3GB virtual memory 1402 space and the remaining part of the 4GB virtual memory space is used 1403 by the kernel to permanently map as much physical memory as 1404 possible. 1405 1406 If the machine has between 1 and 4 Gigabytes physical RAM, then 1407 answer "4GB" here. 1408 1409 If more than 4 Gigabytes is used then answer "64GB" here. This 1410 selection turns Intel PAE (Physical Address Extension) mode on. 1411 PAE implements 3-level paging on IA32 processors. PAE is fully 1412 supported by Linux, PAE mode is implemented on all recent Intel 1413 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1414 then the kernel will not boot on CPUs that don't support PAE! 1415 1416 The actual amount of total physical memory will either be 1417 auto detected or can be forced by using a kernel command line option 1418 such as "mem=256M". (Try "man bootparam" or see the documentation of 1419 your boot loader (lilo or loadlin) about how to pass options to the 1420 kernel at boot time.) 1421 1422 If unsure, say "off". 1423 1424config HIGHMEM4G 1425 bool "4GB" 1426 help 1427 Select this if you have a 32-bit processor and between 1 and 4 1428 gigabytes of physical RAM. 1429 1430config HIGHMEM64G 1431 bool "64GB" 1432 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1433 select X86_PAE 1434 help 1435 Select this if you have a 32-bit processor and more than 4 1436 gigabytes of physical RAM. 1437 1438endchoice 1439 1440choice 1441 prompt "Memory split" if EXPERT 1442 default VMSPLIT_3G 1443 depends on X86_32 1444 help 1445 Select the desired split between kernel and user memory. 1446 1447 If the address range available to the kernel is less than the 1448 physical memory installed, the remaining memory will be available 1449 as "high memory". Accessing high memory is a little more costly 1450 than low memory, as it needs to be mapped into the kernel first. 1451 Note that increasing the kernel address space limits the range 1452 available to user programs, making the address space there 1453 tighter. Selecting anything other than the default 3G/1G split 1454 will also likely make your kernel incompatible with binary-only 1455 kernel modules. 1456 1457 If you are not absolutely sure what you are doing, leave this 1458 option alone! 1459 1460 config VMSPLIT_3G 1461 bool "3G/1G user/kernel split" 1462 config VMSPLIT_3G_OPT 1463 depends on !X86_PAE 1464 bool "3G/1G user/kernel split (for full 1G low memory)" 1465 config VMSPLIT_2G 1466 bool "2G/2G user/kernel split" 1467 config VMSPLIT_2G_OPT 1468 depends on !X86_PAE 1469 bool "2G/2G user/kernel split (for full 2G low memory)" 1470 config VMSPLIT_1G 1471 bool "1G/3G user/kernel split" 1472endchoice 1473 1474config PAGE_OFFSET 1475 hex 1476 default 0xB0000000 if VMSPLIT_3G_OPT 1477 default 0x80000000 if VMSPLIT_2G 1478 default 0x78000000 if VMSPLIT_2G_OPT 1479 default 0x40000000 if VMSPLIT_1G 1480 default 0xC0000000 1481 depends on X86_32 1482 1483config HIGHMEM 1484 def_bool y 1485 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1486 1487config X86_PAE 1488 bool "PAE (Physical Address Extension) Support" 1489 depends on X86_32 && !HIGHMEM4G 1490 select PHYS_ADDR_T_64BIT 1491 select SWIOTLB 1492 help 1493 PAE is required for NX support, and furthermore enables 1494 larger swapspace support for non-overcommit purposes. It 1495 has the cost of more pagetable lookup overhead, and also 1496 consumes more pagetable space per process. 1497 1498config X86_5LEVEL 1499 bool "Enable 5-level page tables support" 1500 default y 1501 select DYNAMIC_MEMORY_LAYOUT 1502 select SPARSEMEM_VMEMMAP 1503 depends on X86_64 1504 help 1505 5-level paging enables access to larger address space: 1506 upto 128 PiB of virtual address space and 4 PiB of 1507 physical address space. 1508 1509 It will be supported by future Intel CPUs. 1510 1511 A kernel with the option enabled can be booted on machines that 1512 support 4- or 5-level paging. 1513 1514 See Documentation/x86/x86_64/5level-paging.rst for more 1515 information. 1516 1517 Say N if unsure. 1518 1519config X86_DIRECT_GBPAGES 1520 def_bool y 1521 depends on X86_64 1522 help 1523 Certain kernel features effectively disable kernel 1524 linear 1 GB mappings (even if the CPU otherwise 1525 supports them), so don't confuse the user by printing 1526 that we have them enabled. 1527 1528config X86_CPA_STATISTICS 1529 bool "Enable statistic for Change Page Attribute" 1530 depends on DEBUG_FS 1531 help 1532 Expose statistics about the Change Page Attribute mechanism, which 1533 helps to determine the effectiveness of preserving large and huge 1534 page mappings when mapping protections are changed. 1535 1536config X86_MEM_ENCRYPT 1537 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1538 select DYNAMIC_PHYSICAL_MASK 1539 def_bool n 1540 1541config AMD_MEM_ENCRYPT 1542 bool "AMD Secure Memory Encryption (SME) support" 1543 depends on X86_64 && CPU_SUP_AMD 1544 select DMA_COHERENT_POOL 1545 select ARCH_USE_MEMREMAP_PROT 1546 select INSTRUCTION_DECODER 1547 select ARCH_HAS_CC_PLATFORM 1548 select X86_MEM_ENCRYPT 1549 help 1550 Say yes to enable support for the encryption of system memory. 1551 This requires an AMD processor that supports Secure Memory 1552 Encryption (SME). 1553 1554config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1555 bool "Activate AMD Secure Memory Encryption (SME) by default" 1556 depends on AMD_MEM_ENCRYPT 1557 help 1558 Say yes to have system memory encrypted by default if running on 1559 an AMD processor that supports Secure Memory Encryption (SME). 1560 1561 If set to Y, then the encryption of system memory can be 1562 deactivated with the mem_encrypt=off command line option. 1563 1564 If set to N, then the encryption of system memory can be 1565 activated with the mem_encrypt=on command line option. 1566 1567# Common NUMA Features 1568config NUMA 1569 bool "NUMA Memory Allocation and Scheduler Support" 1570 depends on SMP 1571 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1572 default y if X86_BIGSMP 1573 select USE_PERCPU_NUMA_NODE_ID 1574 help 1575 Enable NUMA (Non-Uniform Memory Access) support. 1576 1577 The kernel will try to allocate memory used by a CPU on the 1578 local memory controller of the CPU and add some more 1579 NUMA awareness to the kernel. 1580 1581 For 64-bit this is recommended if the system is Intel Core i7 1582 (or later), AMD Opteron, or EM64T NUMA. 1583 1584 For 32-bit this is only needed if you boot a 32-bit 1585 kernel on a 64-bit NUMA platform. 1586 1587 Otherwise, you should say N. 1588 1589config AMD_NUMA 1590 def_bool y 1591 prompt "Old style AMD Opteron NUMA detection" 1592 depends on X86_64 && NUMA && PCI 1593 help 1594 Enable AMD NUMA node topology detection. You should say Y here if 1595 you have a multi processor AMD system. This uses an old method to 1596 read the NUMA configuration directly from the builtin Northbridge 1597 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1598 which also takes priority if both are compiled in. 1599 1600config X86_64_ACPI_NUMA 1601 def_bool y 1602 prompt "ACPI NUMA detection" 1603 depends on X86_64 && NUMA && ACPI && PCI 1604 select ACPI_NUMA 1605 help 1606 Enable ACPI SRAT based node topology detection. 1607 1608config NUMA_EMU 1609 bool "NUMA emulation" 1610 depends on NUMA 1611 help 1612 Enable NUMA emulation. A flat machine will be split 1613 into virtual nodes when booted with "numa=fake=N", where N is the 1614 number of nodes. This is only useful for debugging. 1615 1616config NODES_SHIFT 1617 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1618 range 1 10 1619 default "10" if MAXSMP 1620 default "6" if X86_64 1621 default "3" 1622 depends on NUMA 1623 help 1624 Specify the maximum number of NUMA Nodes available on the target 1625 system. Increases memory reserved to accommodate various tables. 1626 1627config ARCH_FLATMEM_ENABLE 1628 def_bool y 1629 depends on X86_32 && !NUMA 1630 1631config ARCH_SPARSEMEM_ENABLE 1632 def_bool y 1633 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1634 select SPARSEMEM_STATIC if X86_32 1635 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1636 1637config ARCH_SPARSEMEM_DEFAULT 1638 def_bool X86_64 || (NUMA && X86_32) 1639 1640config ARCH_SELECT_MEMORY_MODEL 1641 def_bool y 1642 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1643 1644config ARCH_MEMORY_PROBE 1645 bool "Enable sysfs memory/probe interface" 1646 depends on MEMORY_HOTPLUG 1647 help 1648 This option enables a sysfs memory/probe interface for testing. 1649 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1650 If you are unsure how to answer this question, answer N. 1651 1652config ARCH_PROC_KCORE_TEXT 1653 def_bool y 1654 depends on X86_64 && PROC_KCORE 1655 1656config ILLEGAL_POINTER_VALUE 1657 hex 1658 default 0 if X86_32 1659 default 0xdead000000000000 if X86_64 1660 1661config X86_PMEM_LEGACY_DEVICE 1662 bool 1663 1664config X86_PMEM_LEGACY 1665 tristate "Support non-standard NVDIMMs and ADR protected memory" 1666 depends on PHYS_ADDR_T_64BIT 1667 depends on BLK_DEV 1668 select X86_PMEM_LEGACY_DEVICE 1669 select NUMA_KEEP_MEMINFO if NUMA 1670 select LIBNVDIMM 1671 help 1672 Treat memory marked using the non-standard e820 type of 12 as used 1673 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1674 The kernel will offer these regions to the 'pmem' driver so 1675 they can be used for persistent storage. 1676 1677 Say Y if unsure. 1678 1679config HIGHPTE 1680 bool "Allocate 3rd-level pagetables from highmem" 1681 depends on HIGHMEM 1682 help 1683 The VM uses one page table entry for each page of physical memory. 1684 For systems with a lot of RAM, this can be wasteful of precious 1685 low memory. Setting this option will put user-space page table 1686 entries in high memory. 1687 1688config X86_CHECK_BIOS_CORRUPTION 1689 bool "Check for low memory corruption" 1690 help 1691 Periodically check for memory corruption in low memory, which 1692 is suspected to be caused by BIOS. Even when enabled in the 1693 configuration, it is disabled at runtime. Enable it by 1694 setting "memory_corruption_check=1" on the kernel command 1695 line. By default it scans the low 64k of memory every 60 1696 seconds; see the memory_corruption_check_size and 1697 memory_corruption_check_period parameters in 1698 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1699 1700 When enabled with the default parameters, this option has 1701 almost no overhead, as it reserves a relatively small amount 1702 of memory and scans it infrequently. It both detects corruption 1703 and prevents it from affecting the running system. 1704 1705 It is, however, intended as a diagnostic tool; if repeatable 1706 BIOS-originated corruption always affects the same memory, 1707 you can use memmap= to prevent the kernel from using that 1708 memory. 1709 1710config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1711 bool "Set the default setting of memory_corruption_check" 1712 depends on X86_CHECK_BIOS_CORRUPTION 1713 default y 1714 help 1715 Set whether the default state of memory_corruption_check is 1716 on or off. 1717 1718config MATH_EMULATION 1719 bool 1720 depends on MODIFY_LDT_SYSCALL 1721 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1722 help 1723 Linux can emulate a math coprocessor (used for floating point 1724 operations) if you don't have one. 486DX and Pentium processors have 1725 a math coprocessor built in, 486SX and 386 do not, unless you added 1726 a 487DX or 387, respectively. (The messages during boot time can 1727 give you some hints here ["man dmesg"].) Everyone needs either a 1728 coprocessor or this emulation. 1729 1730 If you don't have a math coprocessor, you need to say Y here; if you 1731 say Y here even though you have a coprocessor, the coprocessor will 1732 be used nevertheless. (This behavior can be changed with the kernel 1733 command line option "no387", which comes handy if your coprocessor 1734 is broken. Try "man bootparam" or see the documentation of your boot 1735 loader (lilo or loadlin) about how to pass options to the kernel at 1736 boot time.) This means that it is a good idea to say Y here if you 1737 intend to use this kernel on different machines. 1738 1739 More information about the internals of the Linux math coprocessor 1740 emulation can be found in <file:arch/x86/math-emu/README>. 1741 1742 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1743 kernel, it won't hurt. 1744 1745config MTRR 1746 def_bool y 1747 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1748 help 1749 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1750 the Memory Type Range Registers (MTRRs) may be used to control 1751 processor access to memory ranges. This is most useful if you have 1752 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1753 allows bus write transfers to be combined into a larger transfer 1754 before bursting over the PCI/AGP bus. This can increase performance 1755 of image write operations 2.5 times or more. Saying Y here creates a 1756 /proc/mtrr file which may be used to manipulate your processor's 1757 MTRRs. Typically the X server should use this. 1758 1759 This code has a reasonably generic interface so that similar 1760 control registers on other processors can be easily supported 1761 as well: 1762 1763 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1764 Registers (ARRs) which provide a similar functionality to MTRRs. For 1765 these, the ARRs are used to emulate the MTRRs. 1766 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1767 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1768 write-combining. All of these processors are supported by this code 1769 and it makes sense to say Y here if you have one of them. 1770 1771 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1772 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1773 can lead to all sorts of problems, so it's good to say Y here. 1774 1775 You can safely say Y even if your machine doesn't have MTRRs, you'll 1776 just add about 9 KB to your kernel. 1777 1778 See <file:Documentation/x86/mtrr.rst> for more information. 1779 1780config MTRR_SANITIZER 1781 def_bool y 1782 prompt "MTRR cleanup support" 1783 depends on MTRR 1784 help 1785 Convert MTRR layout from continuous to discrete, so X drivers can 1786 add writeback entries. 1787 1788 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1789 The largest mtrr entry size for a continuous block can be set with 1790 mtrr_chunk_size. 1791 1792 If unsure, say Y. 1793 1794config MTRR_SANITIZER_ENABLE_DEFAULT 1795 int "MTRR cleanup enable value (0-1)" 1796 range 0 1 1797 default "0" 1798 depends on MTRR_SANITIZER 1799 help 1800 Enable mtrr cleanup default value 1801 1802config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1803 int "MTRR cleanup spare reg num (0-7)" 1804 range 0 7 1805 default "1" 1806 depends on MTRR_SANITIZER 1807 help 1808 mtrr cleanup spare entries default, it can be changed via 1809 mtrr_spare_reg_nr=N on the kernel command line. 1810 1811config X86_PAT 1812 def_bool y 1813 prompt "x86 PAT support" if EXPERT 1814 depends on MTRR 1815 help 1816 Use PAT attributes to setup page level cache control. 1817 1818 PATs are the modern equivalents of MTRRs and are much more 1819 flexible than MTRRs. 1820 1821 Say N here if you see bootup problems (boot crash, boot hang, 1822 spontaneous reboots) or a non-working video driver. 1823 1824 If unsure, say Y. 1825 1826config ARCH_USES_PG_UNCACHED 1827 def_bool y 1828 depends on X86_PAT 1829 1830config X86_UMIP 1831 def_bool y 1832 prompt "User Mode Instruction Prevention" if EXPERT 1833 help 1834 User Mode Instruction Prevention (UMIP) is a security feature in 1835 some x86 processors. If enabled, a general protection fault is 1836 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1837 executed in user mode. These instructions unnecessarily expose 1838 information about the hardware state. 1839 1840 The vast majority of applications do not use these instructions. 1841 For the very few that do, software emulation is provided in 1842 specific cases in protected and virtual-8086 modes. Emulated 1843 results are dummy. 1844 1845config CC_HAS_IBT 1846 # GCC >= 9 and binutils >= 2.29 1847 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1848 # Clang/LLVM >= 14 1849 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1850 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1851 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1852 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1853 $(as-instr,endbr64) 1854 1855config X86_KERNEL_IBT 1856 prompt "Indirect Branch Tracking" 1857 bool 1858 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1859 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1860 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1861 select OBJTOOL 1862 help 1863 Build the kernel with support for Indirect Branch Tracking, a 1864 hardware support course-grain forward-edge Control Flow Integrity 1865 protection. It enforces that all indirect calls must land on 1866 an ENDBR instruction, as such, the compiler will instrument the 1867 code with them to make this happen. 1868 1869 In addition to building the kernel with IBT, seal all functions that 1870 are not indirect call targets, avoiding them ever becoming one. 1871 1872 This requires LTO like objtool runs and will slow down the build. It 1873 does significantly reduce the number of ENDBR instructions in the 1874 kernel image. 1875 1876config X86_INTEL_MEMORY_PROTECTION_KEYS 1877 prompt "Memory Protection Keys" 1878 def_bool y 1879 # Note: only available in 64-bit mode 1880 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1881 select ARCH_USES_HIGH_VMA_FLAGS 1882 select ARCH_HAS_PKEYS 1883 help 1884 Memory Protection Keys provides a mechanism for enforcing 1885 page-based protections, but without requiring modification of the 1886 page tables when an application changes protection domains. 1887 1888 For details, see Documentation/core-api/protection-keys.rst 1889 1890 If unsure, say y. 1891 1892choice 1893 prompt "TSX enable mode" 1894 depends on CPU_SUP_INTEL 1895 default X86_INTEL_TSX_MODE_OFF 1896 help 1897 Intel's TSX (Transactional Synchronization Extensions) feature 1898 allows to optimize locking protocols through lock elision which 1899 can lead to a noticeable performance boost. 1900 1901 On the other hand it has been shown that TSX can be exploited 1902 to form side channel attacks (e.g. TAA) and chances are there 1903 will be more of those attacks discovered in the future. 1904 1905 Therefore TSX is not enabled by default (aka tsx=off). An admin 1906 might override this decision by tsx=on the command line parameter. 1907 Even with TSX enabled, the kernel will attempt to enable the best 1908 possible TAA mitigation setting depending on the microcode available 1909 for the particular machine. 1910 1911 This option allows to set the default tsx mode between tsx=on, =off 1912 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1913 details. 1914 1915 Say off if not sure, auto if TSX is in use but it should be used on safe 1916 platforms or on if TSX is in use and the security aspect of tsx is not 1917 relevant. 1918 1919config X86_INTEL_TSX_MODE_OFF 1920 bool "off" 1921 help 1922 TSX is disabled if possible - equals to tsx=off command line parameter. 1923 1924config X86_INTEL_TSX_MODE_ON 1925 bool "on" 1926 help 1927 TSX is always enabled on TSX capable HW - equals the tsx=on command 1928 line parameter. 1929 1930config X86_INTEL_TSX_MODE_AUTO 1931 bool "auto" 1932 help 1933 TSX is enabled on TSX capable HW that is believed to be safe against 1934 side channel attacks- equals the tsx=auto command line parameter. 1935endchoice 1936 1937config X86_SGX 1938 bool "Software Guard eXtensions (SGX)" 1939 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1940 depends on CRYPTO=y 1941 depends on CRYPTO_SHA256=y 1942 select SRCU 1943 select MMU_NOTIFIER 1944 select NUMA_KEEP_MEMINFO if NUMA 1945 select XARRAY_MULTI 1946 help 1947 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1948 that can be used by applications to set aside private regions of code 1949 and data, referred to as enclaves. An enclave's private memory can 1950 only be accessed by code running within the enclave. Accesses from 1951 outside the enclave, including other enclaves, are disallowed by 1952 hardware. 1953 1954 If unsure, say N. 1955 1956config EFI 1957 bool "EFI runtime service support" 1958 depends on ACPI 1959 select UCS2_STRING 1960 select EFI_RUNTIME_WRAPPERS 1961 select ARCH_USE_MEMREMAP_PROT 1962 help 1963 This enables the kernel to use EFI runtime services that are 1964 available (such as the EFI variable services). 1965 1966 This option is only useful on systems that have EFI firmware. 1967 In addition, you should use the latest ELILO loader available 1968 at <http://elilo.sourceforge.net> in order to take advantage 1969 of EFI runtime services. However, even with this option, the 1970 resultant kernel should continue to boot on existing non-EFI 1971 platforms. 1972 1973config EFI_STUB 1974 bool "EFI stub support" 1975 depends on EFI 1976 depends on $(cc-option,-mabi=ms) || X86_32 1977 select RELOCATABLE 1978 help 1979 This kernel feature allows a bzImage to be loaded directly 1980 by EFI firmware without the use of a bootloader. 1981 1982 See Documentation/admin-guide/efi-stub.rst for more information. 1983 1984config EFI_MIXED 1985 bool "EFI mixed-mode support" 1986 depends on EFI_STUB && X86_64 1987 help 1988 Enabling this feature allows a 64-bit kernel to be booted 1989 on a 32-bit firmware, provided that your CPU supports 64-bit 1990 mode. 1991 1992 Note that it is not possible to boot a mixed-mode enabled 1993 kernel via the EFI boot stub - a bootloader that supports 1994 the EFI handover protocol must be used. 1995 1996 If unsure, say N. 1997 1998source "kernel/Kconfig.hz" 1999 2000config KEXEC 2001 bool "kexec system call" 2002 select KEXEC_CORE 2003 help 2004 kexec is a system call that implements the ability to shutdown your 2005 current kernel, and to start another kernel. It is like a reboot 2006 but it is independent of the system firmware. And like a reboot 2007 you can start any kernel with it, not just Linux. 2008 2009 The name comes from the similarity to the exec system call. 2010 2011 It is an ongoing process to be certain the hardware in a machine 2012 is properly shutdown, so do not be surprised if this code does not 2013 initially work for you. As of this writing the exact hardware 2014 interface is strongly in flux, so no good recommendation can be 2015 made. 2016 2017config KEXEC_FILE 2018 bool "kexec file based system call" 2019 select KEXEC_CORE 2020 select HAVE_IMA_KEXEC if IMA 2021 depends on X86_64 2022 depends on CRYPTO=y 2023 depends on CRYPTO_SHA256=y 2024 help 2025 This is new version of kexec system call. This system call is 2026 file based and takes file descriptors as system call argument 2027 for kernel and initramfs as opposed to list of segments as 2028 accepted by previous system call. 2029 2030config ARCH_HAS_KEXEC_PURGATORY 2031 def_bool KEXEC_FILE 2032 2033config KEXEC_SIG 2034 bool "Verify kernel signature during kexec_file_load() syscall" 2035 depends on KEXEC_FILE 2036 help 2037 2038 This option makes the kexec_file_load() syscall check for a valid 2039 signature of the kernel image. The image can still be loaded without 2040 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2041 there's a signature that we can check, then it must be valid. 2042 2043 In addition to this option, you need to enable signature 2044 verification for the corresponding kernel image type being 2045 loaded in order for this to work. 2046 2047config KEXEC_SIG_FORCE 2048 bool "Require a valid signature in kexec_file_load() syscall" 2049 depends on KEXEC_SIG 2050 help 2051 This option makes kernel signature verification mandatory for 2052 the kexec_file_load() syscall. 2053 2054config KEXEC_BZIMAGE_VERIFY_SIG 2055 bool "Enable bzImage signature verification support" 2056 depends on KEXEC_SIG 2057 depends on SIGNED_PE_FILE_VERIFICATION 2058 select SYSTEM_TRUSTED_KEYRING 2059 help 2060 Enable bzImage signature verification support. 2061 2062config CRASH_DUMP 2063 bool "kernel crash dumps" 2064 depends on X86_64 || (X86_32 && HIGHMEM) 2065 help 2066 Generate crash dump after being started by kexec. 2067 This should be normally only set in special crash dump kernels 2068 which are loaded in the main kernel with kexec-tools into 2069 a specially reserved region and then later executed after 2070 a crash by kdump/kexec. The crash dump kernel must be compiled 2071 to a memory address not used by the main kernel or BIOS using 2072 PHYSICAL_START, or it must be built as a relocatable image 2073 (CONFIG_RELOCATABLE=y). 2074 For more details see Documentation/admin-guide/kdump/kdump.rst 2075 2076config KEXEC_JUMP 2077 bool "kexec jump" 2078 depends on KEXEC && HIBERNATION 2079 help 2080 Jump between original kernel and kexeced kernel and invoke 2081 code in physical address mode via KEXEC 2082 2083config PHYSICAL_START 2084 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2085 default "0x1000000" 2086 help 2087 This gives the physical address where the kernel is loaded. 2088 2089 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2090 bzImage will decompress itself to above physical address and 2091 run from there. Otherwise, bzImage will run from the address where 2092 it has been loaded by the boot loader and will ignore above physical 2093 address. 2094 2095 In normal kdump cases one does not have to set/change this option 2096 as now bzImage can be compiled as a completely relocatable image 2097 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2098 address. This option is mainly useful for the folks who don't want 2099 to use a bzImage for capturing the crash dump and want to use a 2100 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2101 to be specifically compiled to run from a specific memory area 2102 (normally a reserved region) and this option comes handy. 2103 2104 So if you are using bzImage for capturing the crash dump, 2105 leave the value here unchanged to 0x1000000 and set 2106 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2107 for capturing the crash dump change this value to start of 2108 the reserved region. In other words, it can be set based on 2109 the "X" value as specified in the "crashkernel=YM@XM" 2110 command line boot parameter passed to the panic-ed 2111 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2112 for more details about crash dumps. 2113 2114 Usage of bzImage for capturing the crash dump is recommended as 2115 one does not have to build two kernels. Same kernel can be used 2116 as production kernel and capture kernel. Above option should have 2117 gone away after relocatable bzImage support is introduced. But it 2118 is present because there are users out there who continue to use 2119 vmlinux for dump capture. This option should go away down the 2120 line. 2121 2122 Don't change this unless you know what you are doing. 2123 2124config RELOCATABLE 2125 bool "Build a relocatable kernel" 2126 default y 2127 help 2128 This builds a kernel image that retains relocation information 2129 so it can be loaded someplace besides the default 1MB. 2130 The relocations tend to make the kernel binary about 10% larger, 2131 but are discarded at runtime. 2132 2133 One use is for the kexec on panic case where the recovery kernel 2134 must live at a different physical address than the primary 2135 kernel. 2136 2137 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2138 it has been loaded at and the compile time physical address 2139 (CONFIG_PHYSICAL_START) is used as the minimum location. 2140 2141config RANDOMIZE_BASE 2142 bool "Randomize the address of the kernel image (KASLR)" 2143 depends on RELOCATABLE 2144 default y 2145 help 2146 In support of Kernel Address Space Layout Randomization (KASLR), 2147 this randomizes the physical address at which the kernel image 2148 is decompressed and the virtual address where the kernel 2149 image is mapped, as a security feature that deters exploit 2150 attempts relying on knowledge of the location of kernel 2151 code internals. 2152 2153 On 64-bit, the kernel physical and virtual addresses are 2154 randomized separately. The physical address will be anywhere 2155 between 16MB and the top of physical memory (up to 64TB). The 2156 virtual address will be randomized from 16MB up to 1GB (9 bits 2157 of entropy). Note that this also reduces the memory space 2158 available to kernel modules from 1.5GB to 1GB. 2159 2160 On 32-bit, the kernel physical and virtual addresses are 2161 randomized together. They will be randomized from 16MB up to 2162 512MB (8 bits of entropy). 2163 2164 Entropy is generated using the RDRAND instruction if it is 2165 supported. If RDTSC is supported, its value is mixed into 2166 the entropy pool as well. If neither RDRAND nor RDTSC are 2167 supported, then entropy is read from the i8254 timer. The 2168 usable entropy is limited by the kernel being built using 2169 2GB addressing, and that PHYSICAL_ALIGN must be at a 2170 minimum of 2MB. As a result, only 10 bits of entropy are 2171 theoretically possible, but the implementations are further 2172 limited due to memory layouts. 2173 2174 If unsure, say Y. 2175 2176# Relocation on x86 needs some additional build support 2177config X86_NEED_RELOCS 2178 def_bool y 2179 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2180 2181config PHYSICAL_ALIGN 2182 hex "Alignment value to which kernel should be aligned" 2183 default "0x200000" 2184 range 0x2000 0x1000000 if X86_32 2185 range 0x200000 0x1000000 if X86_64 2186 help 2187 This value puts the alignment restrictions on physical address 2188 where kernel is loaded and run from. Kernel is compiled for an 2189 address which meets above alignment restriction. 2190 2191 If bootloader loads the kernel at a non-aligned address and 2192 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2193 address aligned to above value and run from there. 2194 2195 If bootloader loads the kernel at a non-aligned address and 2196 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2197 load address and decompress itself to the address it has been 2198 compiled for and run from there. The address for which kernel is 2199 compiled already meets above alignment restrictions. Hence the 2200 end result is that kernel runs from a physical address meeting 2201 above alignment restrictions. 2202 2203 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2204 this value must be a multiple of 0x200000. 2205 2206 Don't change this unless you know what you are doing. 2207 2208config DYNAMIC_MEMORY_LAYOUT 2209 bool 2210 help 2211 This option makes base addresses of vmalloc and vmemmap as well as 2212 __PAGE_OFFSET movable during boot. 2213 2214config RANDOMIZE_MEMORY 2215 bool "Randomize the kernel memory sections" 2216 depends on X86_64 2217 depends on RANDOMIZE_BASE 2218 select DYNAMIC_MEMORY_LAYOUT 2219 default RANDOMIZE_BASE 2220 help 2221 Randomizes the base virtual address of kernel memory sections 2222 (physical memory mapping, vmalloc & vmemmap). This security feature 2223 makes exploits relying on predictable memory locations less reliable. 2224 2225 The order of allocations remains unchanged. Entropy is generated in 2226 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2227 configuration have in average 30,000 different possible virtual 2228 addresses for each memory section. 2229 2230 If unsure, say Y. 2231 2232config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2233 hex "Physical memory mapping padding" if EXPERT 2234 depends on RANDOMIZE_MEMORY 2235 default "0xa" if MEMORY_HOTPLUG 2236 default "0x0" 2237 range 0x1 0x40 if MEMORY_HOTPLUG 2238 range 0x0 0x40 2239 help 2240 Define the padding in terabytes added to the existing physical 2241 memory size during kernel memory randomization. It is useful 2242 for memory hotplug support but reduces the entropy available for 2243 address randomization. 2244 2245 If unsure, leave at the default value. 2246 2247config HOTPLUG_CPU 2248 def_bool y 2249 depends on SMP 2250 2251config BOOTPARAM_HOTPLUG_CPU0 2252 bool "Set default setting of cpu0_hotpluggable" 2253 depends on HOTPLUG_CPU 2254 help 2255 Set whether default state of cpu0_hotpluggable is on or off. 2256 2257 Say Y here to enable CPU0 hotplug by default. If this switch 2258 is turned on, there is no need to give cpu0_hotplug kernel 2259 parameter and the CPU0 hotplug feature is enabled by default. 2260 2261 Please note: there are two known CPU0 dependencies if you want 2262 to enable the CPU0 hotplug feature either by this switch or by 2263 cpu0_hotplug kernel parameter. 2264 2265 First, resume from hibernate or suspend always starts from CPU0. 2266 So hibernate and suspend are prevented if CPU0 is offline. 2267 2268 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2269 offline if any interrupt can not migrate out of CPU0. There may 2270 be other CPU0 dependencies. 2271 2272 Please make sure the dependencies are under your control before 2273 you enable this feature. 2274 2275 Say N if you don't want to enable CPU0 hotplug feature by default. 2276 You still can enable the CPU0 hotplug feature at boot by kernel 2277 parameter cpu0_hotplug. 2278 2279config DEBUG_HOTPLUG_CPU0 2280 def_bool n 2281 prompt "Debug CPU0 hotplug" 2282 depends on HOTPLUG_CPU 2283 help 2284 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2285 soon as possible and boots up userspace with CPU0 offlined. User 2286 can online CPU0 back after boot time. 2287 2288 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2289 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2290 compilation or giving cpu0_hotplug kernel parameter at boot. 2291 2292 If unsure, say N. 2293 2294config COMPAT_VDSO 2295 def_bool n 2296 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2297 depends on COMPAT_32 2298 help 2299 Certain buggy versions of glibc will crash if they are 2300 presented with a 32-bit vDSO that is not mapped at the address 2301 indicated in its segment table. 2302 2303 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2304 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2305 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2306 the only released version with the bug, but OpenSUSE 9 2307 contains a buggy "glibc 2.3.2". 2308 2309 The symptom of the bug is that everything crashes on startup, saying: 2310 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2311 2312 Saying Y here changes the default value of the vdso32 boot 2313 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2314 This works around the glibc bug but hurts performance. 2315 2316 If unsure, say N: if you are compiling your own kernel, you 2317 are unlikely to be using a buggy version of glibc. 2318 2319choice 2320 prompt "vsyscall table for legacy applications" 2321 depends on X86_64 2322 default LEGACY_VSYSCALL_XONLY 2323 help 2324 Legacy user code that does not know how to find the vDSO expects 2325 to be able to issue three syscalls by calling fixed addresses in 2326 kernel space. Since this location is not randomized with ASLR, 2327 it can be used to assist security vulnerability exploitation. 2328 2329 This setting can be changed at boot time via the kernel command 2330 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2331 is deprecated and can only be enabled using the kernel command 2332 line. 2333 2334 On a system with recent enough glibc (2.14 or newer) and no 2335 static binaries, you can say None without a performance penalty 2336 to improve security. 2337 2338 If unsure, select "Emulate execution only". 2339 2340 config LEGACY_VSYSCALL_XONLY 2341 bool "Emulate execution only" 2342 help 2343 The kernel traps and emulates calls into the fixed vsyscall 2344 address mapping and does not allow reads. This 2345 configuration is recommended when userspace might use the 2346 legacy vsyscall area but support for legacy binary 2347 instrumentation of legacy code is not needed. It mitigates 2348 certain uses of the vsyscall area as an ASLR-bypassing 2349 buffer. 2350 2351 config LEGACY_VSYSCALL_NONE 2352 bool "None" 2353 help 2354 There will be no vsyscall mapping at all. This will 2355 eliminate any risk of ASLR bypass due to the vsyscall 2356 fixed address mapping. Attempts to use the vsyscalls 2357 will be reported to dmesg, so that either old or 2358 malicious userspace programs can be identified. 2359 2360endchoice 2361 2362config CMDLINE_BOOL 2363 bool "Built-in kernel command line" 2364 help 2365 Allow for specifying boot arguments to the kernel at 2366 build time. On some systems (e.g. embedded ones), it is 2367 necessary or convenient to provide some or all of the 2368 kernel boot arguments with the kernel itself (that is, 2369 to not rely on the boot loader to provide them.) 2370 2371 To compile command line arguments into the kernel, 2372 set this option to 'Y', then fill in the 2373 boot arguments in CONFIG_CMDLINE. 2374 2375 Systems with fully functional boot loaders (i.e. non-embedded) 2376 should leave this option set to 'N'. 2377 2378config CMDLINE 2379 string "Built-in kernel command string" 2380 depends on CMDLINE_BOOL 2381 default "" 2382 help 2383 Enter arguments here that should be compiled into the kernel 2384 image and used at boot time. If the boot loader provides a 2385 command line at boot time, it is appended to this string to 2386 form the full kernel command line, when the system boots. 2387 2388 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2389 change this behavior. 2390 2391 In most cases, the command line (whether built-in or provided 2392 by the boot loader) should specify the device for the root 2393 file system. 2394 2395config CMDLINE_OVERRIDE 2396 bool "Built-in command line overrides boot loader arguments" 2397 depends on CMDLINE_BOOL && CMDLINE != "" 2398 help 2399 Set this option to 'Y' to have the kernel ignore the boot loader 2400 command line, and use ONLY the built-in command line. 2401 2402 This is used to work around broken boot loaders. This should 2403 be set to 'N' under normal conditions. 2404 2405config MODIFY_LDT_SYSCALL 2406 bool "Enable the LDT (local descriptor table)" if EXPERT 2407 default y 2408 help 2409 Linux can allow user programs to install a per-process x86 2410 Local Descriptor Table (LDT) using the modify_ldt(2) system 2411 call. This is required to run 16-bit or segmented code such as 2412 DOSEMU or some Wine programs. It is also used by some very old 2413 threading libraries. 2414 2415 Enabling this feature adds a small amount of overhead to 2416 context switches and increases the low-level kernel attack 2417 surface. Disabling it removes the modify_ldt(2) system call. 2418 2419 Saying 'N' here may make sense for embedded or server kernels. 2420 2421config STRICT_SIGALTSTACK_SIZE 2422 bool "Enforce strict size checking for sigaltstack" 2423 depends on DYNAMIC_SIGFRAME 2424 help 2425 For historical reasons MINSIGSTKSZ is a constant which became 2426 already too small with AVX512 support. Add a mechanism to 2427 enforce strict checking of the sigaltstack size against the 2428 real size of the FPU frame. This option enables the check 2429 by default. It can also be controlled via the kernel command 2430 line option 'strict_sas_size' independent of this config 2431 switch. Enabling it might break existing applications which 2432 allocate a too small sigaltstack but 'work' because they 2433 never get a signal delivered. 2434 2435 Say 'N' unless you want to really enforce this check. 2436 2437source "kernel/livepatch/Kconfig" 2438 2439endmenu 2440 2441config CC_HAS_SLS 2442 def_bool $(cc-option,-mharden-sls=all) 2443 2444config CC_HAS_RETURN_THUNK 2445 def_bool $(cc-option,-mfunction-return=thunk-extern) 2446 2447menuconfig SPECULATION_MITIGATIONS 2448 bool "Mitigations for speculative execution vulnerabilities" 2449 default y 2450 help 2451 Say Y here to enable options which enable mitigations for 2452 speculative execution hardware vulnerabilities. 2453 2454 If you say N, all mitigations will be disabled. You really 2455 should know what you are doing to say so. 2456 2457if SPECULATION_MITIGATIONS 2458 2459config PAGE_TABLE_ISOLATION 2460 bool "Remove the kernel mapping in user mode" 2461 default y 2462 depends on (X86_64 || X86_PAE) 2463 help 2464 This feature reduces the number of hardware side channels by 2465 ensuring that the majority of kernel addresses are not mapped 2466 into userspace. 2467 2468 See Documentation/x86/pti.rst for more details. 2469 2470config RETPOLINE 2471 bool "Avoid speculative indirect branches in kernel" 2472 select OBJTOOL if HAVE_OBJTOOL 2473 default y 2474 help 2475 Compile kernel with the retpoline compiler options to guard against 2476 kernel-to-user data leaks by avoiding speculative indirect 2477 branches. Requires a compiler with -mindirect-branch=thunk-extern 2478 support for full protection. The kernel may run slower. 2479 2480config RETHUNK 2481 bool "Enable return-thunks" 2482 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2483 select OBJTOOL if HAVE_OBJTOOL 2484 default y if X86_64 2485 help 2486 Compile the kernel with the return-thunks compiler option to guard 2487 against kernel-to-user data leaks by avoiding return speculation. 2488 Requires a compiler with -mfunction-return=thunk-extern 2489 support for full protection. The kernel may run slower. 2490 2491config CPU_UNRET_ENTRY 2492 bool "Enable UNRET on kernel entry" 2493 depends on CPU_SUP_AMD && RETHUNK && X86_64 2494 default y 2495 help 2496 Compile the kernel with support for the retbleed=unret mitigation. 2497 2498config CPU_IBPB_ENTRY 2499 bool "Enable IBPB on kernel entry" 2500 depends on CPU_SUP_AMD && X86_64 2501 default y 2502 help 2503 Compile the kernel with support for the retbleed=ibpb mitigation. 2504 2505config CPU_IBRS_ENTRY 2506 bool "Enable IBRS on kernel entry" 2507 depends on CPU_SUP_INTEL && X86_64 2508 default y 2509 help 2510 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2511 This mitigates both spectre_v2 and retbleed at great cost to 2512 performance. 2513 2514config SLS 2515 bool "Mitigate Straight-Line-Speculation" 2516 depends on CC_HAS_SLS && X86_64 2517 select OBJTOOL if HAVE_OBJTOOL 2518 default n 2519 help 2520 Compile the kernel with straight-line-speculation options to guard 2521 against straight line speculation. The kernel image might be slightly 2522 larger. 2523 2524endif 2525 2526config ARCH_HAS_ADD_PAGES 2527 def_bool y 2528 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2529 2530config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2531 def_bool y 2532 2533menu "Power management and ACPI options" 2534 2535config ARCH_HIBERNATION_HEADER 2536 def_bool y 2537 depends on HIBERNATION 2538 2539source "kernel/power/Kconfig" 2540 2541source "drivers/acpi/Kconfig" 2542 2543config X86_APM_BOOT 2544 def_bool y 2545 depends on APM 2546 2547menuconfig APM 2548 tristate "APM (Advanced Power Management) BIOS support" 2549 depends on X86_32 && PM_SLEEP 2550 help 2551 APM is a BIOS specification for saving power using several different 2552 techniques. This is mostly useful for battery powered laptops with 2553 APM compliant BIOSes. If you say Y here, the system time will be 2554 reset after a RESUME operation, the /proc/apm device will provide 2555 battery status information, and user-space programs will receive 2556 notification of APM "events" (e.g. battery status change). 2557 2558 If you select "Y" here, you can disable actual use of the APM 2559 BIOS by passing the "apm=off" option to the kernel at boot time. 2560 2561 Note that the APM support is almost completely disabled for 2562 machines with more than one CPU. 2563 2564 In order to use APM, you will need supporting software. For location 2565 and more information, read <file:Documentation/power/apm-acpi.rst> 2566 and the Battery Powered Linux mini-HOWTO, available from 2567 <http://www.tldp.org/docs.html#howto>. 2568 2569 This driver does not spin down disk drives (see the hdparm(8) 2570 manpage ("man 8 hdparm") for that), and it doesn't turn off 2571 VESA-compliant "green" monitors. 2572 2573 This driver does not support the TI 4000M TravelMate and the ACER 2574 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2575 desktop machines also don't have compliant BIOSes, and this driver 2576 may cause those machines to panic during the boot phase. 2577 2578 Generally, if you don't have a battery in your machine, there isn't 2579 much point in using this driver and you should say N. If you get 2580 random kernel OOPSes or reboots that don't seem to be related to 2581 anything, try disabling/enabling this option (or disabling/enabling 2582 APM in your BIOS). 2583 2584 Some other things you should try when experiencing seemingly random, 2585 "weird" problems: 2586 2587 1) make sure that you have enough swap space and that it is 2588 enabled. 2589 2) pass the "idle=poll" option to the kernel 2590 3) switch on floating point emulation in the kernel and pass 2591 the "no387" option to the kernel 2592 4) pass the "floppy=nodma" option to the kernel 2593 5) pass the "mem=4M" option to the kernel (thereby disabling 2594 all but the first 4 MB of RAM) 2595 6) make sure that the CPU is not over clocked. 2596 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2597 8) disable the cache from your BIOS settings 2598 9) install a fan for the video card or exchange video RAM 2599 10) install a better fan for the CPU 2600 11) exchange RAM chips 2601 12) exchange the motherboard. 2602 2603 To compile this driver as a module, choose M here: the 2604 module will be called apm. 2605 2606if APM 2607 2608config APM_IGNORE_USER_SUSPEND 2609 bool "Ignore USER SUSPEND" 2610 help 2611 This option will ignore USER SUSPEND requests. On machines with a 2612 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2613 series notebooks, it is necessary to say Y because of a BIOS bug. 2614 2615config APM_DO_ENABLE 2616 bool "Enable PM at boot time" 2617 help 2618 Enable APM features at boot time. From page 36 of the APM BIOS 2619 specification: "When disabled, the APM BIOS does not automatically 2620 power manage devices, enter the Standby State, enter the Suspend 2621 State, or take power saving steps in response to CPU Idle calls." 2622 This driver will make CPU Idle calls when Linux is idle (unless this 2623 feature is turned off -- see "Do CPU IDLE calls", below). This 2624 should always save battery power, but more complicated APM features 2625 will be dependent on your BIOS implementation. You may need to turn 2626 this option off if your computer hangs at boot time when using APM 2627 support, or if it beeps continuously instead of suspending. Turn 2628 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2629 T400CDT. This is off by default since most machines do fine without 2630 this feature. 2631 2632config APM_CPU_IDLE 2633 depends on CPU_IDLE 2634 bool "Make CPU Idle calls when idle" 2635 help 2636 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2637 On some machines, this can activate improved power savings, such as 2638 a slowed CPU clock rate, when the machine is idle. These idle calls 2639 are made after the idle loop has run for some length of time (e.g., 2640 333 mS). On some machines, this will cause a hang at boot time or 2641 whenever the CPU becomes idle. (On machines with more than one CPU, 2642 this option does nothing.) 2643 2644config APM_DISPLAY_BLANK 2645 bool "Enable console blanking using APM" 2646 help 2647 Enable console blanking using the APM. Some laptops can use this to 2648 turn off the LCD backlight when the screen blanker of the Linux 2649 virtual console blanks the screen. Note that this is only used by 2650 the virtual console screen blanker, and won't turn off the backlight 2651 when using the X Window system. This also doesn't have anything to 2652 do with your VESA-compliant power-saving monitor. Further, this 2653 option doesn't work for all laptops -- it might not turn off your 2654 backlight at all, or it might print a lot of errors to the console, 2655 especially if you are using gpm. 2656 2657config APM_ALLOW_INTS 2658 bool "Allow interrupts during APM BIOS calls" 2659 help 2660 Normally we disable external interrupts while we are making calls to 2661 the APM BIOS as a measure to lessen the effects of a badly behaving 2662 BIOS implementation. The BIOS should reenable interrupts if it 2663 needs to. Unfortunately, some BIOSes do not -- especially those in 2664 many of the newer IBM Thinkpads. If you experience hangs when you 2665 suspend, try setting this to Y. Otherwise, say N. 2666 2667endif # APM 2668 2669source "drivers/cpufreq/Kconfig" 2670 2671source "drivers/cpuidle/Kconfig" 2672 2673source "drivers/idle/Kconfig" 2674 2675endmenu 2676 2677menu "Bus options (PCI etc.)" 2678 2679choice 2680 prompt "PCI access mode" 2681 depends on X86_32 && PCI 2682 default PCI_GOANY 2683 help 2684 On PCI systems, the BIOS can be used to detect the PCI devices and 2685 determine their configuration. However, some old PCI motherboards 2686 have BIOS bugs and may crash if this is done. Also, some embedded 2687 PCI-based systems don't have any BIOS at all. Linux can also try to 2688 detect the PCI hardware directly without using the BIOS. 2689 2690 With this option, you can specify how Linux should detect the 2691 PCI devices. If you choose "BIOS", the BIOS will be used, 2692 if you choose "Direct", the BIOS won't be used, and if you 2693 choose "MMConfig", then PCI Express MMCONFIG will be used. 2694 If you choose "Any", the kernel will try MMCONFIG, then the 2695 direct access method and falls back to the BIOS if that doesn't 2696 work. If unsure, go with the default, which is "Any". 2697 2698config PCI_GOBIOS 2699 bool "BIOS" 2700 2701config PCI_GOMMCONFIG 2702 bool "MMConfig" 2703 2704config PCI_GODIRECT 2705 bool "Direct" 2706 2707config PCI_GOOLPC 2708 bool "OLPC XO-1" 2709 depends on OLPC 2710 2711config PCI_GOANY 2712 bool "Any" 2713 2714endchoice 2715 2716config PCI_BIOS 2717 def_bool y 2718 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2719 2720# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2721config PCI_DIRECT 2722 def_bool y 2723 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2724 2725config PCI_MMCONFIG 2726 bool "Support mmconfig PCI config space access" if X86_64 2727 default y 2728 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2729 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2730 2731config PCI_OLPC 2732 def_bool y 2733 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2734 2735config PCI_XEN 2736 def_bool y 2737 depends on PCI && XEN 2738 2739config MMCONF_FAM10H 2740 def_bool y 2741 depends on X86_64 && PCI_MMCONFIG && ACPI 2742 2743config PCI_CNB20LE_QUIRK 2744 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2745 depends on PCI 2746 help 2747 Read the PCI windows out of the CNB20LE host bridge. This allows 2748 PCI hotplug to work on systems with the CNB20LE chipset which do 2749 not have ACPI. 2750 2751 There's no public spec for this chipset, and this functionality 2752 is known to be incomplete. 2753 2754 You should say N unless you know you need this. 2755 2756config ISA_BUS 2757 bool "ISA bus support on modern systems" if EXPERT 2758 help 2759 Expose ISA bus device drivers and options available for selection and 2760 configuration. Enable this option if your target machine has an ISA 2761 bus. ISA is an older system, displaced by PCI and newer bus 2762 architectures -- if your target machine is modern, it probably does 2763 not have an ISA bus. 2764 2765 If unsure, say N. 2766 2767# x86_64 have no ISA slots, but can have ISA-style DMA. 2768config ISA_DMA_API 2769 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2770 default y 2771 help 2772 Enables ISA-style DMA support for devices requiring such controllers. 2773 If unsure, say Y. 2774 2775if X86_32 2776 2777config ISA 2778 bool "ISA support" 2779 help 2780 Find out whether you have ISA slots on your motherboard. ISA is the 2781 name of a bus system, i.e. the way the CPU talks to the other stuff 2782 inside your box. Other bus systems are PCI, EISA, MicroChannel 2783 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2784 newer boards don't support it. If you have ISA, say Y, otherwise N. 2785 2786config SCx200 2787 tristate "NatSemi SCx200 support" 2788 help 2789 This provides basic support for National Semiconductor's 2790 (now AMD's) Geode processors. The driver probes for the 2791 PCI-IDs of several on-chip devices, so its a good dependency 2792 for other scx200_* drivers. 2793 2794 If compiled as a module, the driver is named scx200. 2795 2796config SCx200HR_TIMER 2797 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2798 depends on SCx200 2799 default y 2800 help 2801 This driver provides a clocksource built upon the on-chip 2802 27MHz high-resolution timer. Its also a workaround for 2803 NSC Geode SC-1100's buggy TSC, which loses time when the 2804 processor goes idle (as is done by the scheduler). The 2805 other workaround is idle=poll boot option. 2806 2807config OLPC 2808 bool "One Laptop Per Child support" 2809 depends on !X86_PAE 2810 select GPIOLIB 2811 select OF 2812 select OF_PROMTREE 2813 select IRQ_DOMAIN 2814 select OLPC_EC 2815 help 2816 Add support for detecting the unique features of the OLPC 2817 XO hardware. 2818 2819config OLPC_XO1_PM 2820 bool "OLPC XO-1 Power Management" 2821 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2822 help 2823 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2824 2825config OLPC_XO1_RTC 2826 bool "OLPC XO-1 Real Time Clock" 2827 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2828 help 2829 Add support for the XO-1 real time clock, which can be used as a 2830 programmable wakeup source. 2831 2832config OLPC_XO1_SCI 2833 bool "OLPC XO-1 SCI extras" 2834 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2835 depends on INPUT=y 2836 select POWER_SUPPLY 2837 help 2838 Add support for SCI-based features of the OLPC XO-1 laptop: 2839 - EC-driven system wakeups 2840 - Power button 2841 - Ebook switch 2842 - Lid switch 2843 - AC adapter status updates 2844 - Battery status updates 2845 2846config OLPC_XO15_SCI 2847 bool "OLPC XO-1.5 SCI extras" 2848 depends on OLPC && ACPI 2849 select POWER_SUPPLY 2850 help 2851 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2852 - EC-driven system wakeups 2853 - AC adapter status updates 2854 - Battery status updates 2855 2856config ALIX 2857 bool "PCEngines ALIX System Support (LED setup)" 2858 select GPIOLIB 2859 help 2860 This option enables system support for the PCEngines ALIX. 2861 At present this just sets up LEDs for GPIO control on 2862 ALIX2/3/6 boards. However, other system specific setup should 2863 get added here. 2864 2865 Note: You must still enable the drivers for GPIO and LED support 2866 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2867 2868 Note: You have to set alix.force=1 for boards with Award BIOS. 2869 2870config NET5501 2871 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2872 select GPIOLIB 2873 help 2874 This option enables system support for the Soekris Engineering net5501. 2875 2876config GEOS 2877 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2878 select GPIOLIB 2879 depends on DMI 2880 help 2881 This option enables system support for the Traverse Technologies GEOS. 2882 2883config TS5500 2884 bool "Technologic Systems TS-5500 platform support" 2885 depends on MELAN 2886 select CHECK_SIGNATURE 2887 select NEW_LEDS 2888 select LEDS_CLASS 2889 help 2890 This option enables system support for the Technologic Systems TS-5500. 2891 2892endif # X86_32 2893 2894config AMD_NB 2895 def_bool y 2896 depends on CPU_SUP_AMD && PCI 2897 2898endmenu 2899 2900menu "Binary Emulations" 2901 2902config IA32_EMULATION 2903 bool "IA32 Emulation" 2904 depends on X86_64 2905 select ARCH_WANT_OLD_COMPAT_IPC 2906 select BINFMT_ELF 2907 select COMPAT_OLD_SIGACTION 2908 help 2909 Include code to run legacy 32-bit programs under a 2910 64-bit kernel. You should likely turn this on, unless you're 2911 100% sure that you don't have any 32-bit programs left. 2912 2913config X86_X32_ABI 2914 bool "x32 ABI for 64-bit mode" 2915 depends on X86_64 2916 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2917 # compressed debug sections to x86_x32 properly: 2918 # https://github.com/ClangBuiltLinux/linux/issues/514 2919 # https://github.com/ClangBuiltLinux/linux/issues/1141 2920 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 2921 help 2922 Include code to run binaries for the x32 native 32-bit ABI 2923 for 64-bit processors. An x32 process gets access to the 2924 full 64-bit register file and wide data path while leaving 2925 pointers at 32 bits for smaller memory footprint. 2926 2927config COMPAT_32 2928 def_bool y 2929 depends on IA32_EMULATION || X86_32 2930 select HAVE_UID16 2931 select OLD_SIGSUSPEND3 2932 2933config COMPAT 2934 def_bool y 2935 depends on IA32_EMULATION || X86_X32_ABI 2936 2937config COMPAT_FOR_U64_ALIGNMENT 2938 def_bool y 2939 depends on COMPAT 2940 2941endmenu 2942 2943config HAVE_ATOMIC_IOMAP 2944 def_bool y 2945 depends on X86_32 2946 2947source "arch/x86/kvm/Kconfig" 2948 2949source "arch/x86/Kconfig.assembler" 2950