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 1113config X86_IO_APIC 1114 def_bool y 1115 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1116 1117config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1118 bool "Reroute for broken boot IRQs" 1119 depends on X86_IO_APIC 1120 help 1121 This option enables a workaround that fixes a source of 1122 spurious interrupts. This is recommended when threaded 1123 interrupt handling is used on systems where the generation of 1124 superfluous "boot interrupts" cannot be disabled. 1125 1126 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1127 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1128 kernel does during interrupt handling). On chipsets where this 1129 boot IRQ generation cannot be disabled, this workaround keeps 1130 the original IRQ line masked so that only the equivalent "boot 1131 IRQ" is delivered to the CPUs. The workaround also tells the 1132 kernel to set up the IRQ handler on the boot IRQ line. In this 1133 way only one interrupt is delivered to the kernel. Otherwise 1134 the spurious second interrupt may cause the kernel to bring 1135 down (vital) interrupt lines. 1136 1137 Only affects "broken" chipsets. Interrupt sharing may be 1138 increased on these systems. 1139 1140config X86_MCE 1141 bool "Machine Check / overheating reporting" 1142 select GENERIC_ALLOCATOR 1143 default y 1144 help 1145 Machine Check support allows the processor to notify the 1146 kernel if it detects a problem (e.g. overheating, data corruption). 1147 The action the kernel takes depends on the severity of the problem, 1148 ranging from warning messages to halting the machine. 1149 1150config X86_MCELOG_LEGACY 1151 bool "Support for deprecated /dev/mcelog character device" 1152 depends on X86_MCE 1153 help 1154 Enable support for /dev/mcelog which is needed by the old mcelog 1155 userspace logging daemon. Consider switching to the new generation 1156 rasdaemon solution. 1157 1158config X86_MCE_INTEL 1159 def_bool y 1160 prompt "Intel MCE features" 1161 depends on X86_MCE && X86_LOCAL_APIC 1162 help 1163 Additional support for intel specific MCE features such as 1164 the thermal monitor. 1165 1166config X86_MCE_AMD 1167 def_bool y 1168 prompt "AMD MCE features" 1169 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1170 help 1171 Additional support for AMD specific MCE features such as 1172 the DRAM Error Threshold. 1173 1174config X86_ANCIENT_MCE 1175 bool "Support for old Pentium 5 / WinChip machine checks" 1176 depends on X86_32 && X86_MCE 1177 help 1178 Include support for machine check handling on old Pentium 5 or WinChip 1179 systems. These typically need to be enabled explicitly on the command 1180 line. 1181 1182config X86_MCE_THRESHOLD 1183 depends on X86_MCE_AMD || X86_MCE_INTEL 1184 def_bool y 1185 1186config X86_MCE_INJECT 1187 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1188 tristate "Machine check injector support" 1189 help 1190 Provide support for injecting machine checks for testing purposes. 1191 If you don't know what a machine check is and you don't do kernel 1192 QA it is safe to say n. 1193 1194source "arch/x86/events/Kconfig" 1195 1196config X86_LEGACY_VM86 1197 bool "Legacy VM86 support" 1198 depends on X86_32 1199 help 1200 This option allows user programs to put the CPU into V8086 1201 mode, which is an 80286-era approximation of 16-bit real mode. 1202 1203 Some very old versions of X and/or vbetool require this option 1204 for user mode setting. Similarly, DOSEMU will use it if 1205 available to accelerate real mode DOS programs. However, any 1206 recent version of DOSEMU, X, or vbetool should be fully 1207 functional even without kernel VM86 support, as they will all 1208 fall back to software emulation. Nevertheless, if you are using 1209 a 16-bit DOS program where 16-bit performance matters, vm86 1210 mode might be faster than emulation and you might want to 1211 enable this option. 1212 1213 Note that any app that works on a 64-bit kernel is unlikely to 1214 need this option, as 64-bit kernels don't, and can't, support 1215 V8086 mode. This option is also unrelated to 16-bit protected 1216 mode and is not needed to run most 16-bit programs under Wine. 1217 1218 Enabling this option increases the complexity of the kernel 1219 and slows down exception handling a tiny bit. 1220 1221 If unsure, say N here. 1222 1223config VM86 1224 bool 1225 default X86_LEGACY_VM86 1226 1227config X86_16BIT 1228 bool "Enable support for 16-bit segments" if EXPERT 1229 default y 1230 depends on MODIFY_LDT_SYSCALL 1231 help 1232 This option is required by programs like Wine to run 16-bit 1233 protected mode legacy code on x86 processors. Disabling 1234 this option saves about 300 bytes on i386, or around 6K text 1235 plus 16K runtime memory on x86-64, 1236 1237config X86_ESPFIX32 1238 def_bool y 1239 depends on X86_16BIT && X86_32 1240 1241config X86_ESPFIX64 1242 def_bool y 1243 depends on X86_16BIT && X86_64 1244 1245config X86_VSYSCALL_EMULATION 1246 bool "Enable vsyscall emulation" if EXPERT 1247 default y 1248 depends on X86_64 1249 help 1250 This enables emulation of the legacy vsyscall page. Disabling 1251 it is roughly equivalent to booting with vsyscall=none, except 1252 that it will also disable the helpful warning if a program 1253 tries to use a vsyscall. With this option set to N, offending 1254 programs will just segfault, citing addresses of the form 1255 0xffffffffff600?00. 1256 1257 This option is required by many programs built before 2013, and 1258 care should be used even with newer programs if set to N. 1259 1260 Disabling this option saves about 7K of kernel size and 1261 possibly 4K of additional runtime pagetable memory. 1262 1263config X86_IOPL_IOPERM 1264 bool "IOPERM and IOPL Emulation" 1265 default y 1266 help 1267 This enables the ioperm() and iopl() syscalls which are necessary 1268 for legacy applications. 1269 1270 Legacy IOPL support is an overbroad mechanism which allows user 1271 space aside of accessing all 65536 I/O ports also to disable 1272 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1273 capabilities and permission from potentially active security 1274 modules. 1275 1276 The emulation restricts the functionality of the syscall to 1277 only allowing the full range I/O port access, but prevents the 1278 ability to disable interrupts from user space which would be 1279 granted if the hardware IOPL mechanism would be used. 1280 1281config TOSHIBA 1282 tristate "Toshiba Laptop support" 1283 depends on X86_32 1284 help 1285 This adds a driver to safely access the System Management Mode of 1286 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1287 not work on models with a Phoenix BIOS. The System Management Mode 1288 is used to set the BIOS and power saving options on Toshiba portables. 1289 1290 For information on utilities to make use of this driver see the 1291 Toshiba Linux utilities web site at: 1292 <http://www.buzzard.org.uk/toshiba/>. 1293 1294 Say Y if you intend to run this kernel on a Toshiba portable. 1295 Say N otherwise. 1296 1297config X86_REBOOTFIXUPS 1298 bool "Enable X86 board specific fixups for reboot" 1299 depends on X86_32 1300 help 1301 This enables chipset and/or board specific fixups to be done 1302 in order to get reboot to work correctly. This is only needed on 1303 some combinations of hardware and BIOS. The symptom, for which 1304 this config is intended, is when reboot ends with a stalled/hung 1305 system. 1306 1307 Currently, the only fixup is for the Geode machines using 1308 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1309 1310 Say Y if you want to enable the fixup. Currently, it's safe to 1311 enable this option even if you don't need it. 1312 Say N otherwise. 1313 1314config MICROCODE 1315 bool "CPU microcode loading support" 1316 default y 1317 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1318 help 1319 If you say Y here, you will be able to update the microcode on 1320 Intel and AMD processors. The Intel support is for the IA32 family, 1321 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1322 AMD support is for families 0x10 and later. You will obviously need 1323 the actual microcode binary data itself which is not shipped with 1324 the Linux kernel. 1325 1326 The preferred method to load microcode from a detached initrd is described 1327 in Documentation/x86/microcode.rst. For that you need to enable 1328 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1329 initrd for microcode blobs. 1330 1331 In addition, you can build the microcode into the kernel. For that you 1332 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1333 config option. 1334 1335config MICROCODE_INTEL 1336 bool "Intel microcode loading support" 1337 depends on CPU_SUP_INTEL && MICROCODE 1338 default MICROCODE 1339 help 1340 This options enables microcode patch loading support for Intel 1341 processors. 1342 1343 For the current Intel microcode data package go to 1344 <https://downloadcenter.intel.com> and search for 1345 'Linux Processor Microcode Data File'. 1346 1347config MICROCODE_AMD 1348 bool "AMD microcode loading support" 1349 depends on CPU_SUP_AMD && MICROCODE 1350 help 1351 If you select this option, microcode patch loading support for AMD 1352 processors will be enabled. 1353 1354config MICROCODE_LATE_LOADING 1355 bool "Late microcode loading (DANGEROUS)" 1356 default n 1357 depends on MICROCODE 1358 help 1359 Loading microcode late, when the system is up and executing instructions 1360 is a tricky business and should be avoided if possible. Just the sequence 1361 of synchronizing all cores and SMT threads is one fragile dance which does 1362 not guarantee that cores might not softlock after the loading. Therefore, 1363 use this at your own risk. Late loading taints the kernel too. 1364 1365config X86_MSR 1366 tristate "/dev/cpu/*/msr - Model-specific register support" 1367 help 1368 This device gives privileged processes access to the x86 1369 Model-Specific Registers (MSRs). It is a character device with 1370 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1371 MSR accesses are directed to a specific CPU on multi-processor 1372 systems. 1373 1374config X86_CPUID 1375 tristate "/dev/cpu/*/cpuid - CPU information support" 1376 help 1377 This device gives processes access to the x86 CPUID instruction to 1378 be executed on a specific processor. It is a character device 1379 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1380 /dev/cpu/31/cpuid. 1381 1382choice 1383 prompt "High Memory Support" 1384 default HIGHMEM4G 1385 depends on X86_32 1386 1387config NOHIGHMEM 1388 bool "off" 1389 help 1390 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1391 However, the address space of 32-bit x86 processors is only 4 1392 Gigabytes large. That means that, if you have a large amount of 1393 physical memory, not all of it can be "permanently mapped" by the 1394 kernel. The physical memory that's not permanently mapped is called 1395 "high memory". 1396 1397 If you are compiling a kernel which will never run on a machine with 1398 more than 1 Gigabyte total physical RAM, answer "off" here (default 1399 choice and suitable for most users). This will result in a "3GB/1GB" 1400 split: 3GB are mapped so that each process sees a 3GB virtual memory 1401 space and the remaining part of the 4GB virtual memory space is used 1402 by the kernel to permanently map as much physical memory as 1403 possible. 1404 1405 If the machine has between 1 and 4 Gigabytes physical RAM, then 1406 answer "4GB" here. 1407 1408 If more than 4 Gigabytes is used then answer "64GB" here. This 1409 selection turns Intel PAE (Physical Address Extension) mode on. 1410 PAE implements 3-level paging on IA32 processors. PAE is fully 1411 supported by Linux, PAE mode is implemented on all recent Intel 1412 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1413 then the kernel will not boot on CPUs that don't support PAE! 1414 1415 The actual amount of total physical memory will either be 1416 auto detected or can be forced by using a kernel command line option 1417 such as "mem=256M". (Try "man bootparam" or see the documentation of 1418 your boot loader (lilo or loadlin) about how to pass options to the 1419 kernel at boot time.) 1420 1421 If unsure, say "off". 1422 1423config HIGHMEM4G 1424 bool "4GB" 1425 help 1426 Select this if you have a 32-bit processor and between 1 and 4 1427 gigabytes of physical RAM. 1428 1429config HIGHMEM64G 1430 bool "64GB" 1431 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1432 select X86_PAE 1433 help 1434 Select this if you have a 32-bit processor and more than 4 1435 gigabytes of physical RAM. 1436 1437endchoice 1438 1439choice 1440 prompt "Memory split" if EXPERT 1441 default VMSPLIT_3G 1442 depends on X86_32 1443 help 1444 Select the desired split between kernel and user memory. 1445 1446 If the address range available to the kernel is less than the 1447 physical memory installed, the remaining memory will be available 1448 as "high memory". Accessing high memory is a little more costly 1449 than low memory, as it needs to be mapped into the kernel first. 1450 Note that increasing the kernel address space limits the range 1451 available to user programs, making the address space there 1452 tighter. Selecting anything other than the default 3G/1G split 1453 will also likely make your kernel incompatible with binary-only 1454 kernel modules. 1455 1456 If you are not absolutely sure what you are doing, leave this 1457 option alone! 1458 1459 config VMSPLIT_3G 1460 bool "3G/1G user/kernel split" 1461 config VMSPLIT_3G_OPT 1462 depends on !X86_PAE 1463 bool "3G/1G user/kernel split (for full 1G low memory)" 1464 config VMSPLIT_2G 1465 bool "2G/2G user/kernel split" 1466 config VMSPLIT_2G_OPT 1467 depends on !X86_PAE 1468 bool "2G/2G user/kernel split (for full 2G low memory)" 1469 config VMSPLIT_1G 1470 bool "1G/3G user/kernel split" 1471endchoice 1472 1473config PAGE_OFFSET 1474 hex 1475 default 0xB0000000 if VMSPLIT_3G_OPT 1476 default 0x80000000 if VMSPLIT_2G 1477 default 0x78000000 if VMSPLIT_2G_OPT 1478 default 0x40000000 if VMSPLIT_1G 1479 default 0xC0000000 1480 depends on X86_32 1481 1482config HIGHMEM 1483 def_bool y 1484 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1485 1486config X86_PAE 1487 bool "PAE (Physical Address Extension) Support" 1488 depends on X86_32 && !HIGHMEM4G 1489 select PHYS_ADDR_T_64BIT 1490 select SWIOTLB 1491 help 1492 PAE is required for NX support, and furthermore enables 1493 larger swapspace support for non-overcommit purposes. It 1494 has the cost of more pagetable lookup overhead, and also 1495 consumes more pagetable space per process. 1496 1497config X86_5LEVEL 1498 bool "Enable 5-level page tables support" 1499 default y 1500 select DYNAMIC_MEMORY_LAYOUT 1501 select SPARSEMEM_VMEMMAP 1502 depends on X86_64 1503 help 1504 5-level paging enables access to larger address space: 1505 upto 128 PiB of virtual address space and 4 PiB of 1506 physical address space. 1507 1508 It will be supported by future Intel CPUs. 1509 1510 A kernel with the option enabled can be booted on machines that 1511 support 4- or 5-level paging. 1512 1513 See Documentation/x86/x86_64/5level-paging.rst for more 1514 information. 1515 1516 Say N if unsure. 1517 1518config X86_DIRECT_GBPAGES 1519 def_bool y 1520 depends on X86_64 1521 help 1522 Certain kernel features effectively disable kernel 1523 linear 1 GB mappings (even if the CPU otherwise 1524 supports them), so don't confuse the user by printing 1525 that we have them enabled. 1526 1527config X86_CPA_STATISTICS 1528 bool "Enable statistic for Change Page Attribute" 1529 depends on DEBUG_FS 1530 help 1531 Expose statistics about the Change Page Attribute mechanism, which 1532 helps to determine the effectiveness of preserving large and huge 1533 page mappings when mapping protections are changed. 1534 1535config X86_MEM_ENCRYPT 1536 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1537 select DYNAMIC_PHYSICAL_MASK 1538 def_bool n 1539 1540config AMD_MEM_ENCRYPT 1541 bool "AMD Secure Memory Encryption (SME) support" 1542 depends on X86_64 && CPU_SUP_AMD 1543 select DMA_COHERENT_POOL 1544 select ARCH_USE_MEMREMAP_PROT 1545 select INSTRUCTION_DECODER 1546 select ARCH_HAS_CC_PLATFORM 1547 select X86_MEM_ENCRYPT 1548 help 1549 Say yes to enable support for the encryption of system memory. 1550 This requires an AMD processor that supports Secure Memory 1551 Encryption (SME). 1552 1553config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1554 bool "Activate AMD Secure Memory Encryption (SME) by default" 1555 depends on AMD_MEM_ENCRYPT 1556 help 1557 Say yes to have system memory encrypted by default if running on 1558 an AMD processor that supports Secure Memory Encryption (SME). 1559 1560 If set to Y, then the encryption of system memory can be 1561 deactivated with the mem_encrypt=off command line option. 1562 1563 If set to N, then the encryption of system memory can be 1564 activated with the mem_encrypt=on command line option. 1565 1566# Common NUMA Features 1567config NUMA 1568 bool "NUMA Memory Allocation and Scheduler Support" 1569 depends on SMP 1570 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1571 default y if X86_BIGSMP 1572 select USE_PERCPU_NUMA_NODE_ID 1573 help 1574 Enable NUMA (Non-Uniform Memory Access) support. 1575 1576 The kernel will try to allocate memory used by a CPU on the 1577 local memory controller of the CPU and add some more 1578 NUMA awareness to the kernel. 1579 1580 For 64-bit this is recommended if the system is Intel Core i7 1581 (or later), AMD Opteron, or EM64T NUMA. 1582 1583 For 32-bit this is only needed if you boot a 32-bit 1584 kernel on a 64-bit NUMA platform. 1585 1586 Otherwise, you should say N. 1587 1588config AMD_NUMA 1589 def_bool y 1590 prompt "Old style AMD Opteron NUMA detection" 1591 depends on X86_64 && NUMA && PCI 1592 help 1593 Enable AMD NUMA node topology detection. You should say Y here if 1594 you have a multi processor AMD system. This uses an old method to 1595 read the NUMA configuration directly from the builtin Northbridge 1596 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1597 which also takes priority if both are compiled in. 1598 1599config X86_64_ACPI_NUMA 1600 def_bool y 1601 prompt "ACPI NUMA detection" 1602 depends on X86_64 && NUMA && ACPI && PCI 1603 select ACPI_NUMA 1604 help 1605 Enable ACPI SRAT based node topology detection. 1606 1607config NUMA_EMU 1608 bool "NUMA emulation" 1609 depends on NUMA 1610 help 1611 Enable NUMA emulation. A flat machine will be split 1612 into virtual nodes when booted with "numa=fake=N", where N is the 1613 number of nodes. This is only useful for debugging. 1614 1615config NODES_SHIFT 1616 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1617 range 1 10 1618 default "10" if MAXSMP 1619 default "6" if X86_64 1620 default "3" 1621 depends on NUMA 1622 help 1623 Specify the maximum number of NUMA Nodes available on the target 1624 system. Increases memory reserved to accommodate various tables. 1625 1626config ARCH_FLATMEM_ENABLE 1627 def_bool y 1628 depends on X86_32 && !NUMA 1629 1630config ARCH_SPARSEMEM_ENABLE 1631 def_bool y 1632 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1633 select SPARSEMEM_STATIC if X86_32 1634 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1635 1636config ARCH_SPARSEMEM_DEFAULT 1637 def_bool X86_64 || (NUMA && X86_32) 1638 1639config ARCH_SELECT_MEMORY_MODEL 1640 def_bool y 1641 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1642 1643config ARCH_MEMORY_PROBE 1644 bool "Enable sysfs memory/probe interface" 1645 depends on MEMORY_HOTPLUG 1646 help 1647 This option enables a sysfs memory/probe interface for testing. 1648 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1649 If you are unsure how to answer this question, answer N. 1650 1651config ARCH_PROC_KCORE_TEXT 1652 def_bool y 1653 depends on X86_64 && PROC_KCORE 1654 1655config ILLEGAL_POINTER_VALUE 1656 hex 1657 default 0 if X86_32 1658 default 0xdead000000000000 if X86_64 1659 1660config X86_PMEM_LEGACY_DEVICE 1661 bool 1662 1663config X86_PMEM_LEGACY 1664 tristate "Support non-standard NVDIMMs and ADR protected memory" 1665 depends on PHYS_ADDR_T_64BIT 1666 depends on BLK_DEV 1667 select X86_PMEM_LEGACY_DEVICE 1668 select NUMA_KEEP_MEMINFO if NUMA 1669 select LIBNVDIMM 1670 help 1671 Treat memory marked using the non-standard e820 type of 12 as used 1672 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1673 The kernel will offer these regions to the 'pmem' driver so 1674 they can be used for persistent storage. 1675 1676 Say Y if unsure. 1677 1678config HIGHPTE 1679 bool "Allocate 3rd-level pagetables from highmem" 1680 depends on HIGHMEM 1681 help 1682 The VM uses one page table entry for each page of physical memory. 1683 For systems with a lot of RAM, this can be wasteful of precious 1684 low memory. Setting this option will put user-space page table 1685 entries in high memory. 1686 1687config X86_CHECK_BIOS_CORRUPTION 1688 bool "Check for low memory corruption" 1689 help 1690 Periodically check for memory corruption in low memory, which 1691 is suspected to be caused by BIOS. Even when enabled in the 1692 configuration, it is disabled at runtime. Enable it by 1693 setting "memory_corruption_check=1" on the kernel command 1694 line. By default it scans the low 64k of memory every 60 1695 seconds; see the memory_corruption_check_size and 1696 memory_corruption_check_period parameters in 1697 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1698 1699 When enabled with the default parameters, this option has 1700 almost no overhead, as it reserves a relatively small amount 1701 of memory and scans it infrequently. It both detects corruption 1702 and prevents it from affecting the running system. 1703 1704 It is, however, intended as a diagnostic tool; if repeatable 1705 BIOS-originated corruption always affects the same memory, 1706 you can use memmap= to prevent the kernel from using that 1707 memory. 1708 1709config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1710 bool "Set the default setting of memory_corruption_check" 1711 depends on X86_CHECK_BIOS_CORRUPTION 1712 default y 1713 help 1714 Set whether the default state of memory_corruption_check is 1715 on or off. 1716 1717config MATH_EMULATION 1718 bool 1719 depends on MODIFY_LDT_SYSCALL 1720 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1721 help 1722 Linux can emulate a math coprocessor (used for floating point 1723 operations) if you don't have one. 486DX and Pentium processors have 1724 a math coprocessor built in, 486SX and 386 do not, unless you added 1725 a 487DX or 387, respectively. (The messages during boot time can 1726 give you some hints here ["man dmesg"].) Everyone needs either a 1727 coprocessor or this emulation. 1728 1729 If you don't have a math coprocessor, you need to say Y here; if you 1730 say Y here even though you have a coprocessor, the coprocessor will 1731 be used nevertheless. (This behavior can be changed with the kernel 1732 command line option "no387", which comes handy if your coprocessor 1733 is broken. Try "man bootparam" or see the documentation of your boot 1734 loader (lilo or loadlin) about how to pass options to the kernel at 1735 boot time.) This means that it is a good idea to say Y here if you 1736 intend to use this kernel on different machines. 1737 1738 More information about the internals of the Linux math coprocessor 1739 emulation can be found in <file:arch/x86/math-emu/README>. 1740 1741 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1742 kernel, it won't hurt. 1743 1744config MTRR 1745 def_bool y 1746 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1747 help 1748 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1749 the Memory Type Range Registers (MTRRs) may be used to control 1750 processor access to memory ranges. This is most useful if you have 1751 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1752 allows bus write transfers to be combined into a larger transfer 1753 before bursting over the PCI/AGP bus. This can increase performance 1754 of image write operations 2.5 times or more. Saying Y here creates a 1755 /proc/mtrr file which may be used to manipulate your processor's 1756 MTRRs. Typically the X server should use this. 1757 1758 This code has a reasonably generic interface so that similar 1759 control registers on other processors can be easily supported 1760 as well: 1761 1762 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1763 Registers (ARRs) which provide a similar functionality to MTRRs. For 1764 these, the ARRs are used to emulate the MTRRs. 1765 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1766 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1767 write-combining. All of these processors are supported by this code 1768 and it makes sense to say Y here if you have one of them. 1769 1770 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1771 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1772 can lead to all sorts of problems, so it's good to say Y here. 1773 1774 You can safely say Y even if your machine doesn't have MTRRs, you'll 1775 just add about 9 KB to your kernel. 1776 1777 See <file:Documentation/x86/mtrr.rst> for more information. 1778 1779config MTRR_SANITIZER 1780 def_bool y 1781 prompt "MTRR cleanup support" 1782 depends on MTRR 1783 help 1784 Convert MTRR layout from continuous to discrete, so X drivers can 1785 add writeback entries. 1786 1787 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1788 The largest mtrr entry size for a continuous block can be set with 1789 mtrr_chunk_size. 1790 1791 If unsure, say Y. 1792 1793config MTRR_SANITIZER_ENABLE_DEFAULT 1794 int "MTRR cleanup enable value (0-1)" 1795 range 0 1 1796 default "0" 1797 depends on MTRR_SANITIZER 1798 help 1799 Enable mtrr cleanup default value 1800 1801config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1802 int "MTRR cleanup spare reg num (0-7)" 1803 range 0 7 1804 default "1" 1805 depends on MTRR_SANITIZER 1806 help 1807 mtrr cleanup spare entries default, it can be changed via 1808 mtrr_spare_reg_nr=N on the kernel command line. 1809 1810config X86_PAT 1811 def_bool y 1812 prompt "x86 PAT support" if EXPERT 1813 depends on MTRR 1814 help 1815 Use PAT attributes to setup page level cache control. 1816 1817 PATs are the modern equivalents of MTRRs and are much more 1818 flexible than MTRRs. 1819 1820 Say N here if you see bootup problems (boot crash, boot hang, 1821 spontaneous reboots) or a non-working video driver. 1822 1823 If unsure, say Y. 1824 1825config ARCH_USES_PG_UNCACHED 1826 def_bool y 1827 depends on X86_PAT 1828 1829config X86_UMIP 1830 def_bool y 1831 prompt "User Mode Instruction Prevention" if EXPERT 1832 help 1833 User Mode Instruction Prevention (UMIP) is a security feature in 1834 some x86 processors. If enabled, a general protection fault is 1835 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1836 executed in user mode. These instructions unnecessarily expose 1837 information about the hardware state. 1838 1839 The vast majority of applications do not use these instructions. 1840 For the very few that do, software emulation is provided in 1841 specific cases in protected and virtual-8086 modes. Emulated 1842 results are dummy. 1843 1844config CC_HAS_IBT 1845 # GCC >= 9 and binutils >= 2.29 1846 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1847 # Clang/LLVM >= 14 1848 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1849 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1850 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1851 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1852 $(as-instr,endbr64) 1853 1854config X86_KERNEL_IBT 1855 prompt "Indirect Branch Tracking" 1856 bool 1857 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1858 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1859 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1860 select OBJTOOL 1861 help 1862 Build the kernel with support for Indirect Branch Tracking, a 1863 hardware support course-grain forward-edge Control Flow Integrity 1864 protection. It enforces that all indirect calls must land on 1865 an ENDBR instruction, as such, the compiler will instrument the 1866 code with them to make this happen. 1867 1868 In addition to building the kernel with IBT, seal all functions that 1869 are not indirect call targets, avoiding them ever becoming one. 1870 1871 This requires LTO like objtool runs and will slow down the build. It 1872 does significantly reduce the number of ENDBR instructions in the 1873 kernel image. 1874 1875config X86_INTEL_MEMORY_PROTECTION_KEYS 1876 prompt "Memory Protection Keys" 1877 def_bool y 1878 # Note: only available in 64-bit mode 1879 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1880 select ARCH_USES_HIGH_VMA_FLAGS 1881 select ARCH_HAS_PKEYS 1882 help 1883 Memory Protection Keys provides a mechanism for enforcing 1884 page-based protections, but without requiring modification of the 1885 page tables when an application changes protection domains. 1886 1887 For details, see Documentation/core-api/protection-keys.rst 1888 1889 If unsure, say y. 1890 1891choice 1892 prompt "TSX enable mode" 1893 depends on CPU_SUP_INTEL 1894 default X86_INTEL_TSX_MODE_OFF 1895 help 1896 Intel's TSX (Transactional Synchronization Extensions) feature 1897 allows to optimize locking protocols through lock elision which 1898 can lead to a noticeable performance boost. 1899 1900 On the other hand it has been shown that TSX can be exploited 1901 to form side channel attacks (e.g. TAA) and chances are there 1902 will be more of those attacks discovered in the future. 1903 1904 Therefore TSX is not enabled by default (aka tsx=off). An admin 1905 might override this decision by tsx=on the command line parameter. 1906 Even with TSX enabled, the kernel will attempt to enable the best 1907 possible TAA mitigation setting depending on the microcode available 1908 for the particular machine. 1909 1910 This option allows to set the default tsx mode between tsx=on, =off 1911 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1912 details. 1913 1914 Say off if not sure, auto if TSX is in use but it should be used on safe 1915 platforms or on if TSX is in use and the security aspect of tsx is not 1916 relevant. 1917 1918config X86_INTEL_TSX_MODE_OFF 1919 bool "off" 1920 help 1921 TSX is disabled if possible - equals to tsx=off command line parameter. 1922 1923config X86_INTEL_TSX_MODE_ON 1924 bool "on" 1925 help 1926 TSX is always enabled on TSX capable HW - equals the tsx=on command 1927 line parameter. 1928 1929config X86_INTEL_TSX_MODE_AUTO 1930 bool "auto" 1931 help 1932 TSX is enabled on TSX capable HW that is believed to be safe against 1933 side channel attacks- equals the tsx=auto command line parameter. 1934endchoice 1935 1936config X86_SGX 1937 bool "Software Guard eXtensions (SGX)" 1938 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1939 depends on CRYPTO=y 1940 depends on CRYPTO_SHA256=y 1941 select SRCU 1942 select MMU_NOTIFIER 1943 select NUMA_KEEP_MEMINFO if NUMA 1944 select XARRAY_MULTI 1945 help 1946 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1947 that can be used by applications to set aside private regions of code 1948 and data, referred to as enclaves. An enclave's private memory can 1949 only be accessed by code running within the enclave. Accesses from 1950 outside the enclave, including other enclaves, are disallowed by 1951 hardware. 1952 1953 If unsure, say N. 1954 1955config EFI 1956 bool "EFI runtime service support" 1957 depends on ACPI 1958 select UCS2_STRING 1959 select EFI_RUNTIME_WRAPPERS 1960 select ARCH_USE_MEMREMAP_PROT 1961 help 1962 This enables the kernel to use EFI runtime services that are 1963 available (such as the EFI variable services). 1964 1965 This option is only useful on systems that have EFI firmware. 1966 In addition, you should use the latest ELILO loader available 1967 at <http://elilo.sourceforge.net> in order to take advantage 1968 of EFI runtime services. However, even with this option, the 1969 resultant kernel should continue to boot on existing non-EFI 1970 platforms. 1971 1972config EFI_STUB 1973 bool "EFI stub support" 1974 depends on EFI 1975 select RELOCATABLE 1976 help 1977 This kernel feature allows a bzImage to be loaded directly 1978 by EFI firmware without the use of a bootloader. 1979 1980 See Documentation/admin-guide/efi-stub.rst for more information. 1981 1982config EFI_MIXED 1983 bool "EFI mixed-mode support" 1984 depends on EFI_STUB && X86_64 1985 help 1986 Enabling this feature allows a 64-bit kernel to be booted 1987 on a 32-bit firmware, provided that your CPU supports 64-bit 1988 mode. 1989 1990 Note that it is not possible to boot a mixed-mode enabled 1991 kernel via the EFI boot stub - a bootloader that supports 1992 the EFI handover protocol must be used. 1993 1994 If unsure, say N. 1995 1996source "kernel/Kconfig.hz" 1997 1998config KEXEC 1999 bool "kexec system call" 2000 select KEXEC_CORE 2001 help 2002 kexec is a system call that implements the ability to shutdown your 2003 current kernel, and to start another kernel. It is like a reboot 2004 but it is independent of the system firmware. And like a reboot 2005 you can start any kernel with it, not just Linux. 2006 2007 The name comes from the similarity to the exec system call. 2008 2009 It is an ongoing process to be certain the hardware in a machine 2010 is properly shutdown, so do not be surprised if this code does not 2011 initially work for you. As of this writing the exact hardware 2012 interface is strongly in flux, so no good recommendation can be 2013 made. 2014 2015config KEXEC_FILE 2016 bool "kexec file based system call" 2017 select KEXEC_CORE 2018 select HAVE_IMA_KEXEC if IMA 2019 depends on X86_64 2020 depends on CRYPTO=y 2021 depends on CRYPTO_SHA256=y 2022 help 2023 This is new version of kexec system call. This system call is 2024 file based and takes file descriptors as system call argument 2025 for kernel and initramfs as opposed to list of segments as 2026 accepted by previous system call. 2027 2028config ARCH_HAS_KEXEC_PURGATORY 2029 def_bool KEXEC_FILE 2030 2031config KEXEC_SIG 2032 bool "Verify kernel signature during kexec_file_load() syscall" 2033 depends on KEXEC_FILE 2034 help 2035 2036 This option makes the kexec_file_load() syscall check for a valid 2037 signature of the kernel image. The image can still be loaded without 2038 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2039 there's a signature that we can check, then it must be valid. 2040 2041 In addition to this option, you need to enable signature 2042 verification for the corresponding kernel image type being 2043 loaded in order for this to work. 2044 2045config KEXEC_SIG_FORCE 2046 bool "Require a valid signature in kexec_file_load() syscall" 2047 depends on KEXEC_SIG 2048 help 2049 This option makes kernel signature verification mandatory for 2050 the kexec_file_load() syscall. 2051 2052config KEXEC_BZIMAGE_VERIFY_SIG 2053 bool "Enable bzImage signature verification support" 2054 depends on KEXEC_SIG 2055 depends on SIGNED_PE_FILE_VERIFICATION 2056 select SYSTEM_TRUSTED_KEYRING 2057 help 2058 Enable bzImage signature verification support. 2059 2060config CRASH_DUMP 2061 bool "kernel crash dumps" 2062 depends on X86_64 || (X86_32 && HIGHMEM) 2063 help 2064 Generate crash dump after being started by kexec. 2065 This should be normally only set in special crash dump kernels 2066 which are loaded in the main kernel with kexec-tools into 2067 a specially reserved region and then later executed after 2068 a crash by kdump/kexec. The crash dump kernel must be compiled 2069 to a memory address not used by the main kernel or BIOS using 2070 PHYSICAL_START, or it must be built as a relocatable image 2071 (CONFIG_RELOCATABLE=y). 2072 For more details see Documentation/admin-guide/kdump/kdump.rst 2073 2074config KEXEC_JUMP 2075 bool "kexec jump" 2076 depends on KEXEC && HIBERNATION 2077 help 2078 Jump between original kernel and kexeced kernel and invoke 2079 code in physical address mode via KEXEC 2080 2081config PHYSICAL_START 2082 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2083 default "0x1000000" 2084 help 2085 This gives the physical address where the kernel is loaded. 2086 2087 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2088 bzImage will decompress itself to above physical address and 2089 run from there. Otherwise, bzImage will run from the address where 2090 it has been loaded by the boot loader and will ignore above physical 2091 address. 2092 2093 In normal kdump cases one does not have to set/change this option 2094 as now bzImage can be compiled as a completely relocatable image 2095 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2096 address. This option is mainly useful for the folks who don't want 2097 to use a bzImage for capturing the crash dump and want to use a 2098 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2099 to be specifically compiled to run from a specific memory area 2100 (normally a reserved region) and this option comes handy. 2101 2102 So if you are using bzImage for capturing the crash dump, 2103 leave the value here unchanged to 0x1000000 and set 2104 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2105 for capturing the crash dump change this value to start of 2106 the reserved region. In other words, it can be set based on 2107 the "X" value as specified in the "crashkernel=YM@XM" 2108 command line boot parameter passed to the panic-ed 2109 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2110 for more details about crash dumps. 2111 2112 Usage of bzImage for capturing the crash dump is recommended as 2113 one does not have to build two kernels. Same kernel can be used 2114 as production kernel and capture kernel. Above option should have 2115 gone away after relocatable bzImage support is introduced. But it 2116 is present because there are users out there who continue to use 2117 vmlinux for dump capture. This option should go away down the 2118 line. 2119 2120 Don't change this unless you know what you are doing. 2121 2122config RELOCATABLE 2123 bool "Build a relocatable kernel" 2124 default y 2125 help 2126 This builds a kernel image that retains relocation information 2127 so it can be loaded someplace besides the default 1MB. 2128 The relocations tend to make the kernel binary about 10% larger, 2129 but are discarded at runtime. 2130 2131 One use is for the kexec on panic case where the recovery kernel 2132 must live at a different physical address than the primary 2133 kernel. 2134 2135 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2136 it has been loaded at and the compile time physical address 2137 (CONFIG_PHYSICAL_START) is used as the minimum location. 2138 2139config RANDOMIZE_BASE 2140 bool "Randomize the address of the kernel image (KASLR)" 2141 depends on RELOCATABLE 2142 default y 2143 help 2144 In support of Kernel Address Space Layout Randomization (KASLR), 2145 this randomizes the physical address at which the kernel image 2146 is decompressed and the virtual address where the kernel 2147 image is mapped, as a security feature that deters exploit 2148 attempts relying on knowledge of the location of kernel 2149 code internals. 2150 2151 On 64-bit, the kernel physical and virtual addresses are 2152 randomized separately. The physical address will be anywhere 2153 between 16MB and the top of physical memory (up to 64TB). The 2154 virtual address will be randomized from 16MB up to 1GB (9 bits 2155 of entropy). Note that this also reduces the memory space 2156 available to kernel modules from 1.5GB to 1GB. 2157 2158 On 32-bit, the kernel physical and virtual addresses are 2159 randomized together. They will be randomized from 16MB up to 2160 512MB (8 bits of entropy). 2161 2162 Entropy is generated using the RDRAND instruction if it is 2163 supported. If RDTSC is supported, its value is mixed into 2164 the entropy pool as well. If neither RDRAND nor RDTSC are 2165 supported, then entropy is read from the i8254 timer. The 2166 usable entropy is limited by the kernel being built using 2167 2GB addressing, and that PHYSICAL_ALIGN must be at a 2168 minimum of 2MB. As a result, only 10 bits of entropy are 2169 theoretically possible, but the implementations are further 2170 limited due to memory layouts. 2171 2172 If unsure, say Y. 2173 2174# Relocation on x86 needs some additional build support 2175config X86_NEED_RELOCS 2176 def_bool y 2177 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2178 2179config PHYSICAL_ALIGN 2180 hex "Alignment value to which kernel should be aligned" 2181 default "0x200000" 2182 range 0x2000 0x1000000 if X86_32 2183 range 0x200000 0x1000000 if X86_64 2184 help 2185 This value puts the alignment restrictions on physical address 2186 where kernel is loaded and run from. Kernel is compiled for an 2187 address which meets above alignment restriction. 2188 2189 If bootloader loads the kernel at a non-aligned address and 2190 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2191 address aligned to above value and run from there. 2192 2193 If bootloader loads the kernel at a non-aligned address and 2194 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2195 load address and decompress itself to the address it has been 2196 compiled for and run from there. The address for which kernel is 2197 compiled already meets above alignment restrictions. Hence the 2198 end result is that kernel runs from a physical address meeting 2199 above alignment restrictions. 2200 2201 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2202 this value must be a multiple of 0x200000. 2203 2204 Don't change this unless you know what you are doing. 2205 2206config DYNAMIC_MEMORY_LAYOUT 2207 bool 2208 help 2209 This option makes base addresses of vmalloc and vmemmap as well as 2210 __PAGE_OFFSET movable during boot. 2211 2212config RANDOMIZE_MEMORY 2213 bool "Randomize the kernel memory sections" 2214 depends on X86_64 2215 depends on RANDOMIZE_BASE 2216 select DYNAMIC_MEMORY_LAYOUT 2217 default RANDOMIZE_BASE 2218 help 2219 Randomizes the base virtual address of kernel memory sections 2220 (physical memory mapping, vmalloc & vmemmap). This security feature 2221 makes exploits relying on predictable memory locations less reliable. 2222 2223 The order of allocations remains unchanged. Entropy is generated in 2224 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2225 configuration have in average 30,000 different possible virtual 2226 addresses for each memory section. 2227 2228 If unsure, say Y. 2229 2230config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2231 hex "Physical memory mapping padding" if EXPERT 2232 depends on RANDOMIZE_MEMORY 2233 default "0xa" if MEMORY_HOTPLUG 2234 default "0x0" 2235 range 0x1 0x40 if MEMORY_HOTPLUG 2236 range 0x0 0x40 2237 help 2238 Define the padding in terabytes added to the existing physical 2239 memory size during kernel memory randomization. It is useful 2240 for memory hotplug support but reduces the entropy available for 2241 address randomization. 2242 2243 If unsure, leave at the default value. 2244 2245config HOTPLUG_CPU 2246 def_bool y 2247 depends on SMP 2248 2249config BOOTPARAM_HOTPLUG_CPU0 2250 bool "Set default setting of cpu0_hotpluggable" 2251 depends on HOTPLUG_CPU 2252 help 2253 Set whether default state of cpu0_hotpluggable is on or off. 2254 2255 Say Y here to enable CPU0 hotplug by default. If this switch 2256 is turned on, there is no need to give cpu0_hotplug kernel 2257 parameter and the CPU0 hotplug feature is enabled by default. 2258 2259 Please note: there are two known CPU0 dependencies if you want 2260 to enable the CPU0 hotplug feature either by this switch or by 2261 cpu0_hotplug kernel parameter. 2262 2263 First, resume from hibernate or suspend always starts from CPU0. 2264 So hibernate and suspend are prevented if CPU0 is offline. 2265 2266 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2267 offline if any interrupt can not migrate out of CPU0. There may 2268 be other CPU0 dependencies. 2269 2270 Please make sure the dependencies are under your control before 2271 you enable this feature. 2272 2273 Say N if you don't want to enable CPU0 hotplug feature by default. 2274 You still can enable the CPU0 hotplug feature at boot by kernel 2275 parameter cpu0_hotplug. 2276 2277config DEBUG_HOTPLUG_CPU0 2278 def_bool n 2279 prompt "Debug CPU0 hotplug" 2280 depends on HOTPLUG_CPU 2281 help 2282 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2283 soon as possible and boots up userspace with CPU0 offlined. User 2284 can online CPU0 back after boot time. 2285 2286 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2287 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2288 compilation or giving cpu0_hotplug kernel parameter at boot. 2289 2290 If unsure, say N. 2291 2292config COMPAT_VDSO 2293 def_bool n 2294 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2295 depends on COMPAT_32 2296 help 2297 Certain buggy versions of glibc will crash if they are 2298 presented with a 32-bit vDSO that is not mapped at the address 2299 indicated in its segment table. 2300 2301 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2302 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2303 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2304 the only released version with the bug, but OpenSUSE 9 2305 contains a buggy "glibc 2.3.2". 2306 2307 The symptom of the bug is that everything crashes on startup, saying: 2308 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2309 2310 Saying Y here changes the default value of the vdso32 boot 2311 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2312 This works around the glibc bug but hurts performance. 2313 2314 If unsure, say N: if you are compiling your own kernel, you 2315 are unlikely to be using a buggy version of glibc. 2316 2317choice 2318 prompt "vsyscall table for legacy applications" 2319 depends on X86_64 2320 default LEGACY_VSYSCALL_XONLY 2321 help 2322 Legacy user code that does not know how to find the vDSO expects 2323 to be able to issue three syscalls by calling fixed addresses in 2324 kernel space. Since this location is not randomized with ASLR, 2325 it can be used to assist security vulnerability exploitation. 2326 2327 This setting can be changed at boot time via the kernel command 2328 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2329 is deprecated and can only be enabled using the kernel command 2330 line. 2331 2332 On a system with recent enough glibc (2.14 or newer) and no 2333 static binaries, you can say None without a performance penalty 2334 to improve security. 2335 2336 If unsure, select "Emulate execution only". 2337 2338 config LEGACY_VSYSCALL_XONLY 2339 bool "Emulate execution only" 2340 help 2341 The kernel traps and emulates calls into the fixed vsyscall 2342 address mapping and does not allow reads. This 2343 configuration is recommended when userspace might use the 2344 legacy vsyscall area but support for legacy binary 2345 instrumentation of legacy code is not needed. It mitigates 2346 certain uses of the vsyscall area as an ASLR-bypassing 2347 buffer. 2348 2349 config LEGACY_VSYSCALL_NONE 2350 bool "None" 2351 help 2352 There will be no vsyscall mapping at all. This will 2353 eliminate any risk of ASLR bypass due to the vsyscall 2354 fixed address mapping. Attempts to use the vsyscalls 2355 will be reported to dmesg, so that either old or 2356 malicious userspace programs can be identified. 2357 2358endchoice 2359 2360config CMDLINE_BOOL 2361 bool "Built-in kernel command line" 2362 help 2363 Allow for specifying boot arguments to the kernel at 2364 build time. On some systems (e.g. embedded ones), it is 2365 necessary or convenient to provide some or all of the 2366 kernel boot arguments with the kernel itself (that is, 2367 to not rely on the boot loader to provide them.) 2368 2369 To compile command line arguments into the kernel, 2370 set this option to 'Y', then fill in the 2371 boot arguments in CONFIG_CMDLINE. 2372 2373 Systems with fully functional boot loaders (i.e. non-embedded) 2374 should leave this option set to 'N'. 2375 2376config CMDLINE 2377 string "Built-in kernel command string" 2378 depends on CMDLINE_BOOL 2379 default "" 2380 help 2381 Enter arguments here that should be compiled into the kernel 2382 image and used at boot time. If the boot loader provides a 2383 command line at boot time, it is appended to this string to 2384 form the full kernel command line, when the system boots. 2385 2386 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2387 change this behavior. 2388 2389 In most cases, the command line (whether built-in or provided 2390 by the boot loader) should specify the device for the root 2391 file system. 2392 2393config CMDLINE_OVERRIDE 2394 bool "Built-in command line overrides boot loader arguments" 2395 depends on CMDLINE_BOOL && CMDLINE != "" 2396 help 2397 Set this option to 'Y' to have the kernel ignore the boot loader 2398 command line, and use ONLY the built-in command line. 2399 2400 This is used to work around broken boot loaders. This should 2401 be set to 'N' under normal conditions. 2402 2403config MODIFY_LDT_SYSCALL 2404 bool "Enable the LDT (local descriptor table)" if EXPERT 2405 default y 2406 help 2407 Linux can allow user programs to install a per-process x86 2408 Local Descriptor Table (LDT) using the modify_ldt(2) system 2409 call. This is required to run 16-bit or segmented code such as 2410 DOSEMU or some Wine programs. It is also used by some very old 2411 threading libraries. 2412 2413 Enabling this feature adds a small amount of overhead to 2414 context switches and increases the low-level kernel attack 2415 surface. Disabling it removes the modify_ldt(2) system call. 2416 2417 Saying 'N' here may make sense for embedded or server kernels. 2418 2419config STRICT_SIGALTSTACK_SIZE 2420 bool "Enforce strict size checking for sigaltstack" 2421 depends on DYNAMIC_SIGFRAME 2422 help 2423 For historical reasons MINSIGSTKSZ is a constant which became 2424 already too small with AVX512 support. Add a mechanism to 2425 enforce strict checking of the sigaltstack size against the 2426 real size of the FPU frame. This option enables the check 2427 by default. It can also be controlled via the kernel command 2428 line option 'strict_sas_size' independent of this config 2429 switch. Enabling it might break existing applications which 2430 allocate a too small sigaltstack but 'work' because they 2431 never get a signal delivered. 2432 2433 Say 'N' unless you want to really enforce this check. 2434 2435source "kernel/livepatch/Kconfig" 2436 2437endmenu 2438 2439config CC_HAS_SLS 2440 def_bool $(cc-option,-mharden-sls=all) 2441 2442config CC_HAS_RETURN_THUNK 2443 def_bool $(cc-option,-mfunction-return=thunk-extern) 2444 2445menuconfig SPECULATION_MITIGATIONS 2446 bool "Mitigations for speculative execution vulnerabilities" 2447 default y 2448 help 2449 Say Y here to enable options which enable mitigations for 2450 speculative execution hardware vulnerabilities. 2451 2452 If you say N, all mitigations will be disabled. You really 2453 should know what you are doing to say so. 2454 2455if SPECULATION_MITIGATIONS 2456 2457config PAGE_TABLE_ISOLATION 2458 bool "Remove the kernel mapping in user mode" 2459 default y 2460 depends on (X86_64 || X86_PAE) 2461 help 2462 This feature reduces the number of hardware side channels by 2463 ensuring that the majority of kernel addresses are not mapped 2464 into userspace. 2465 2466 See Documentation/x86/pti.rst for more details. 2467 2468config RETPOLINE 2469 bool "Avoid speculative indirect branches in kernel" 2470 select OBJTOOL if HAVE_OBJTOOL 2471 default y 2472 help 2473 Compile kernel with the retpoline compiler options to guard against 2474 kernel-to-user data leaks by avoiding speculative indirect 2475 branches. Requires a compiler with -mindirect-branch=thunk-extern 2476 support for full protection. The kernel may run slower. 2477 2478config RETHUNK 2479 bool "Enable return-thunks" 2480 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2481 select OBJTOOL if HAVE_OBJTOOL 2482 default y if X86_64 2483 help 2484 Compile the kernel with the return-thunks compiler option to guard 2485 against kernel-to-user data leaks by avoiding return speculation. 2486 Requires a compiler with -mfunction-return=thunk-extern 2487 support for full protection. The kernel may run slower. 2488 2489config CPU_UNRET_ENTRY 2490 bool "Enable UNRET on kernel entry" 2491 depends on CPU_SUP_AMD && RETHUNK && X86_64 2492 default y 2493 help 2494 Compile the kernel with support for the retbleed=unret mitigation. 2495 2496config CPU_IBPB_ENTRY 2497 bool "Enable IBPB on kernel entry" 2498 depends on CPU_SUP_AMD && X86_64 2499 default y 2500 help 2501 Compile the kernel with support for the retbleed=ibpb mitigation. 2502 2503config CPU_IBRS_ENTRY 2504 bool "Enable IBRS on kernel entry" 2505 depends on CPU_SUP_INTEL && X86_64 2506 default y 2507 help 2508 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2509 This mitigates both spectre_v2 and retbleed at great cost to 2510 performance. 2511 2512config SLS 2513 bool "Mitigate Straight-Line-Speculation" 2514 depends on CC_HAS_SLS && X86_64 2515 select OBJTOOL if HAVE_OBJTOOL 2516 default n 2517 help 2518 Compile the kernel with straight-line-speculation options to guard 2519 against straight line speculation. The kernel image might be slightly 2520 larger. 2521 2522endif 2523 2524config ARCH_HAS_ADD_PAGES 2525 def_bool y 2526 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2527 2528config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2529 def_bool y 2530 2531menu "Power management and ACPI options" 2532 2533config ARCH_HIBERNATION_HEADER 2534 def_bool y 2535 depends on HIBERNATION 2536 2537source "kernel/power/Kconfig" 2538 2539source "drivers/acpi/Kconfig" 2540 2541config X86_APM_BOOT 2542 def_bool y 2543 depends on APM 2544 2545menuconfig APM 2546 tristate "APM (Advanced Power Management) BIOS support" 2547 depends on X86_32 && PM_SLEEP 2548 help 2549 APM is a BIOS specification for saving power using several different 2550 techniques. This is mostly useful for battery powered laptops with 2551 APM compliant BIOSes. If you say Y here, the system time will be 2552 reset after a RESUME operation, the /proc/apm device will provide 2553 battery status information, and user-space programs will receive 2554 notification of APM "events" (e.g. battery status change). 2555 2556 If you select "Y" here, you can disable actual use of the APM 2557 BIOS by passing the "apm=off" option to the kernel at boot time. 2558 2559 Note that the APM support is almost completely disabled for 2560 machines with more than one CPU. 2561 2562 In order to use APM, you will need supporting software. For location 2563 and more information, read <file:Documentation/power/apm-acpi.rst> 2564 and the Battery Powered Linux mini-HOWTO, available from 2565 <http://www.tldp.org/docs.html#howto>. 2566 2567 This driver does not spin down disk drives (see the hdparm(8) 2568 manpage ("man 8 hdparm") for that), and it doesn't turn off 2569 VESA-compliant "green" monitors. 2570 2571 This driver does not support the TI 4000M TravelMate and the ACER 2572 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2573 desktop machines also don't have compliant BIOSes, and this driver 2574 may cause those machines to panic during the boot phase. 2575 2576 Generally, if you don't have a battery in your machine, there isn't 2577 much point in using this driver and you should say N. If you get 2578 random kernel OOPSes or reboots that don't seem to be related to 2579 anything, try disabling/enabling this option (or disabling/enabling 2580 APM in your BIOS). 2581 2582 Some other things you should try when experiencing seemingly random, 2583 "weird" problems: 2584 2585 1) make sure that you have enough swap space and that it is 2586 enabled. 2587 2) pass the "idle=poll" option to the kernel 2588 3) switch on floating point emulation in the kernel and pass 2589 the "no387" option to the kernel 2590 4) pass the "floppy=nodma" option to the kernel 2591 5) pass the "mem=4M" option to the kernel (thereby disabling 2592 all but the first 4 MB of RAM) 2593 6) make sure that the CPU is not over clocked. 2594 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2595 8) disable the cache from your BIOS settings 2596 9) install a fan for the video card or exchange video RAM 2597 10) install a better fan for the CPU 2598 11) exchange RAM chips 2599 12) exchange the motherboard. 2600 2601 To compile this driver as a module, choose M here: the 2602 module will be called apm. 2603 2604if APM 2605 2606config APM_IGNORE_USER_SUSPEND 2607 bool "Ignore USER SUSPEND" 2608 help 2609 This option will ignore USER SUSPEND requests. On machines with a 2610 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2611 series notebooks, it is necessary to say Y because of a BIOS bug. 2612 2613config APM_DO_ENABLE 2614 bool "Enable PM at boot time" 2615 help 2616 Enable APM features at boot time. From page 36 of the APM BIOS 2617 specification: "When disabled, the APM BIOS does not automatically 2618 power manage devices, enter the Standby State, enter the Suspend 2619 State, or take power saving steps in response to CPU Idle calls." 2620 This driver will make CPU Idle calls when Linux is idle (unless this 2621 feature is turned off -- see "Do CPU IDLE calls", below). This 2622 should always save battery power, but more complicated APM features 2623 will be dependent on your BIOS implementation. You may need to turn 2624 this option off if your computer hangs at boot time when using APM 2625 support, or if it beeps continuously instead of suspending. Turn 2626 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2627 T400CDT. This is off by default since most machines do fine without 2628 this feature. 2629 2630config APM_CPU_IDLE 2631 depends on CPU_IDLE 2632 bool "Make CPU Idle calls when idle" 2633 help 2634 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2635 On some machines, this can activate improved power savings, such as 2636 a slowed CPU clock rate, when the machine is idle. These idle calls 2637 are made after the idle loop has run for some length of time (e.g., 2638 333 mS). On some machines, this will cause a hang at boot time or 2639 whenever the CPU becomes idle. (On machines with more than one CPU, 2640 this option does nothing.) 2641 2642config APM_DISPLAY_BLANK 2643 bool "Enable console blanking using APM" 2644 help 2645 Enable console blanking using the APM. Some laptops can use this to 2646 turn off the LCD backlight when the screen blanker of the Linux 2647 virtual console blanks the screen. Note that this is only used by 2648 the virtual console screen blanker, and won't turn off the backlight 2649 when using the X Window system. This also doesn't have anything to 2650 do with your VESA-compliant power-saving monitor. Further, this 2651 option doesn't work for all laptops -- it might not turn off your 2652 backlight at all, or it might print a lot of errors to the console, 2653 especially if you are using gpm. 2654 2655config APM_ALLOW_INTS 2656 bool "Allow interrupts during APM BIOS calls" 2657 help 2658 Normally we disable external interrupts while we are making calls to 2659 the APM BIOS as a measure to lessen the effects of a badly behaving 2660 BIOS implementation. The BIOS should reenable interrupts if it 2661 needs to. Unfortunately, some BIOSes do not -- especially those in 2662 many of the newer IBM Thinkpads. If you experience hangs when you 2663 suspend, try setting this to Y. Otherwise, say N. 2664 2665endif # APM 2666 2667source "drivers/cpufreq/Kconfig" 2668 2669source "drivers/cpuidle/Kconfig" 2670 2671source "drivers/idle/Kconfig" 2672 2673endmenu 2674 2675menu "Bus options (PCI etc.)" 2676 2677choice 2678 prompt "PCI access mode" 2679 depends on X86_32 && PCI 2680 default PCI_GOANY 2681 help 2682 On PCI systems, the BIOS can be used to detect the PCI devices and 2683 determine their configuration. However, some old PCI motherboards 2684 have BIOS bugs and may crash if this is done. Also, some embedded 2685 PCI-based systems don't have any BIOS at all. Linux can also try to 2686 detect the PCI hardware directly without using the BIOS. 2687 2688 With this option, you can specify how Linux should detect the 2689 PCI devices. If you choose "BIOS", the BIOS will be used, 2690 if you choose "Direct", the BIOS won't be used, and if you 2691 choose "MMConfig", then PCI Express MMCONFIG will be used. 2692 If you choose "Any", the kernel will try MMCONFIG, then the 2693 direct access method and falls back to the BIOS if that doesn't 2694 work. If unsure, go with the default, which is "Any". 2695 2696config PCI_GOBIOS 2697 bool "BIOS" 2698 2699config PCI_GOMMCONFIG 2700 bool "MMConfig" 2701 2702config PCI_GODIRECT 2703 bool "Direct" 2704 2705config PCI_GOOLPC 2706 bool "OLPC XO-1" 2707 depends on OLPC 2708 2709config PCI_GOANY 2710 bool "Any" 2711 2712endchoice 2713 2714config PCI_BIOS 2715 def_bool y 2716 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2717 2718# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2719config PCI_DIRECT 2720 def_bool y 2721 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2722 2723config PCI_MMCONFIG 2724 bool "Support mmconfig PCI config space access" if X86_64 2725 default y 2726 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2727 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2728 2729config PCI_OLPC 2730 def_bool y 2731 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2732 2733config PCI_XEN 2734 def_bool y 2735 depends on PCI && XEN 2736 2737config MMCONF_FAM10H 2738 def_bool y 2739 depends on X86_64 && PCI_MMCONFIG && ACPI 2740 2741config PCI_CNB20LE_QUIRK 2742 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2743 depends on PCI 2744 help 2745 Read the PCI windows out of the CNB20LE host bridge. This allows 2746 PCI hotplug to work on systems with the CNB20LE chipset which do 2747 not have ACPI. 2748 2749 There's no public spec for this chipset, and this functionality 2750 is known to be incomplete. 2751 2752 You should say N unless you know you need this. 2753 2754config ISA_BUS 2755 bool "ISA bus support on modern systems" if EXPERT 2756 help 2757 Expose ISA bus device drivers and options available for selection and 2758 configuration. Enable this option if your target machine has an ISA 2759 bus. ISA is an older system, displaced by PCI and newer bus 2760 architectures -- if your target machine is modern, it probably does 2761 not have an ISA bus. 2762 2763 If unsure, say N. 2764 2765# x86_64 have no ISA slots, but can have ISA-style DMA. 2766config ISA_DMA_API 2767 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2768 default y 2769 help 2770 Enables ISA-style DMA support for devices requiring such controllers. 2771 If unsure, say Y. 2772 2773if X86_32 2774 2775config ISA 2776 bool "ISA support" 2777 help 2778 Find out whether you have ISA slots on your motherboard. ISA is the 2779 name of a bus system, i.e. the way the CPU talks to the other stuff 2780 inside your box. Other bus systems are PCI, EISA, MicroChannel 2781 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2782 newer boards don't support it. If you have ISA, say Y, otherwise N. 2783 2784config SCx200 2785 tristate "NatSemi SCx200 support" 2786 help 2787 This provides basic support for National Semiconductor's 2788 (now AMD's) Geode processors. The driver probes for the 2789 PCI-IDs of several on-chip devices, so its a good dependency 2790 for other scx200_* drivers. 2791 2792 If compiled as a module, the driver is named scx200. 2793 2794config SCx200HR_TIMER 2795 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2796 depends on SCx200 2797 default y 2798 help 2799 This driver provides a clocksource built upon the on-chip 2800 27MHz high-resolution timer. Its also a workaround for 2801 NSC Geode SC-1100's buggy TSC, which loses time when the 2802 processor goes idle (as is done by the scheduler). The 2803 other workaround is idle=poll boot option. 2804 2805config OLPC 2806 bool "One Laptop Per Child support" 2807 depends on !X86_PAE 2808 select GPIOLIB 2809 select OF 2810 select OF_PROMTREE 2811 select IRQ_DOMAIN 2812 select OLPC_EC 2813 help 2814 Add support for detecting the unique features of the OLPC 2815 XO hardware. 2816 2817config OLPC_XO1_PM 2818 bool "OLPC XO-1 Power Management" 2819 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2820 help 2821 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2822 2823config OLPC_XO1_RTC 2824 bool "OLPC XO-1 Real Time Clock" 2825 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2826 help 2827 Add support for the XO-1 real time clock, which can be used as a 2828 programmable wakeup source. 2829 2830config OLPC_XO1_SCI 2831 bool "OLPC XO-1 SCI extras" 2832 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2833 depends on INPUT=y 2834 select POWER_SUPPLY 2835 help 2836 Add support for SCI-based features of the OLPC XO-1 laptop: 2837 - EC-driven system wakeups 2838 - Power button 2839 - Ebook switch 2840 - Lid switch 2841 - AC adapter status updates 2842 - Battery status updates 2843 2844config OLPC_XO15_SCI 2845 bool "OLPC XO-1.5 SCI extras" 2846 depends on OLPC && ACPI 2847 select POWER_SUPPLY 2848 help 2849 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2850 - EC-driven system wakeups 2851 - AC adapter status updates 2852 - Battery status updates 2853 2854config ALIX 2855 bool "PCEngines ALIX System Support (LED setup)" 2856 select GPIOLIB 2857 help 2858 This option enables system support for the PCEngines ALIX. 2859 At present this just sets up LEDs for GPIO control on 2860 ALIX2/3/6 boards. However, other system specific setup should 2861 get added here. 2862 2863 Note: You must still enable the drivers for GPIO and LED support 2864 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2865 2866 Note: You have to set alix.force=1 for boards with Award BIOS. 2867 2868config NET5501 2869 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2870 select GPIOLIB 2871 help 2872 This option enables system support for the Soekris Engineering net5501. 2873 2874config GEOS 2875 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2876 select GPIOLIB 2877 depends on DMI 2878 help 2879 This option enables system support for the Traverse Technologies GEOS. 2880 2881config TS5500 2882 bool "Technologic Systems TS-5500 platform support" 2883 depends on MELAN 2884 select CHECK_SIGNATURE 2885 select NEW_LEDS 2886 select LEDS_CLASS 2887 help 2888 This option enables system support for the Technologic Systems TS-5500. 2889 2890endif # X86_32 2891 2892config AMD_NB 2893 def_bool y 2894 depends on CPU_SUP_AMD && PCI 2895 2896endmenu 2897 2898menu "Binary Emulations" 2899 2900config IA32_EMULATION 2901 bool "IA32 Emulation" 2902 depends on X86_64 2903 select ARCH_WANT_OLD_COMPAT_IPC 2904 select BINFMT_ELF 2905 select COMPAT_OLD_SIGACTION 2906 help 2907 Include code to run legacy 32-bit programs under a 2908 64-bit kernel. You should likely turn this on, unless you're 2909 100% sure that you don't have any 32-bit programs left. 2910 2911config X86_X32_ABI 2912 bool "x32 ABI for 64-bit mode" 2913 depends on X86_64 2914 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2915 # compressed debug sections to x86_x32 properly: 2916 # https://github.com/ClangBuiltLinux/linux/issues/514 2917 # https://github.com/ClangBuiltLinux/linux/issues/1141 2918 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 2919 help 2920 Include code to run binaries for the x32 native 32-bit ABI 2921 for 64-bit processors. An x32 process gets access to the 2922 full 64-bit register file and wide data path while leaving 2923 pointers at 32 bits for smaller memory footprint. 2924 2925config COMPAT_32 2926 def_bool y 2927 depends on IA32_EMULATION || X86_32 2928 select HAVE_UID16 2929 select OLD_SIGSUSPEND3 2930 2931config COMPAT 2932 def_bool y 2933 depends on IA32_EMULATION || X86_X32_ABI 2934 2935config COMPAT_FOR_U64_ALIGNMENT 2936 def_bool y 2937 depends on COMPAT 2938 2939endmenu 2940 2941config HAVE_ATOMIC_IOMAP 2942 def_bool y 2943 depends on X86_32 2944 2945source "arch/x86/kvm/Kconfig" 2946 2947source "arch/x86/Kconfig.assembler" 2948