1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_USE_CMPXCHG_LOCKREF 31 select HAVE_ARCH_SOFT_DIRTY 32 select MODULES_USE_ELF_RELA 33 select NEED_DMA_MAP_STATE 34 select SWIOTLB 35 select ARCH_HAS_ELFCORE_COMPAT 36 select ZONE_DMA32 37 38config FORCE_DYNAMIC_FTRACE 39 def_bool y 40 depends on X86_32 41 depends on FUNCTION_TRACER 42 select DYNAMIC_FTRACE 43 help 44 We keep the static function tracing (!DYNAMIC_FTRACE) around 45 in order to test the non static function tracing in the 46 generic code, as other architectures still use it. But we 47 only need to keep it around for x86_64. No need to keep it 48 for x86_32. For x86_32, force DYNAMIC_FTRACE. 49# 50# Arch settings 51# 52# ( Note that options that are marked 'if X86_64' could in principle be 53# ported to 32-bit as well. ) 54# 55config X86 56 def_bool y 57 # 58 # Note: keep this list sorted alphabetically 59 # 60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 62 select ARCH_32BIT_OFF_T if X86_32 63 select ARCH_CLOCKSOURCE_INIT 64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 71 select ARCH_HAS_CACHE_LINE_SIZE 72 select ARCH_HAS_CURRENT_STACK_POINTER 73 select ARCH_HAS_DEBUG_VIRTUAL 74 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 75 select ARCH_HAS_DEVMEM_IS_ALLOWED 76 select ARCH_HAS_EARLY_DEBUG if KGDB 77 select ARCH_HAS_ELF_RANDOMIZE 78 select ARCH_HAS_FAST_MULTIPLIER 79 select ARCH_HAS_FORTIFY_SOURCE 80 select ARCH_HAS_GCOV_PROFILE_ALL 81 select ARCH_HAS_KCOV if X86_64 82 select ARCH_HAS_MEM_ENCRYPT 83 select ARCH_HAS_MEMBARRIER_SYNC_CORE 84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 85 select ARCH_HAS_PMEM_API if X86_64 86 select ARCH_HAS_PTE_DEVMAP if X86_64 87 select ARCH_HAS_PTE_SPECIAL 88 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 89 select ARCH_HAS_COPY_MC if X86_64 90 select ARCH_HAS_SET_MEMORY 91 select ARCH_HAS_SET_DIRECT_MAP 92 select ARCH_HAS_STRICT_KERNEL_RWX 93 select ARCH_HAS_STRICT_MODULE_RWX 94 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 95 select ARCH_HAS_SYSCALL_WRAPPER 96 select ARCH_HAS_UBSAN_SANITIZE_ALL 97 select ARCH_HAS_VM_GET_PAGE_PROT 98 select ARCH_HAS_DEBUG_WX 99 select ARCH_HAS_ZONE_DMA_SET if EXPERT 100 select ARCH_HAVE_NMI_SAFE_CMPXCHG 101 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 102 select ARCH_MIGHT_HAVE_PC_PARPORT 103 select ARCH_MIGHT_HAVE_PC_SERIO 104 select ARCH_STACKWALK 105 select ARCH_SUPPORTS_ACPI 106 select ARCH_SUPPORTS_ATOMIC_RMW 107 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 108 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 109 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 110 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 111 select ARCH_SUPPORTS_LTO_CLANG 112 select ARCH_SUPPORTS_LTO_CLANG_THIN 113 select ARCH_USE_BUILTIN_BSWAP 114 select ARCH_USE_MEMTEST 115 select ARCH_USE_QUEUED_RWLOCKS 116 select ARCH_USE_QUEUED_SPINLOCKS 117 select ARCH_USE_SYM_ANNOTATIONS 118 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 119 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 120 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 121 select ARCH_WANTS_NO_INSTR 122 select ARCH_WANT_GENERAL_HUGETLB 123 select ARCH_WANT_HUGE_PMD_SHARE 124 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64 125 select ARCH_WANT_LD_ORPHAN_WARN 126 select ARCH_WANTS_THP_SWAP if X86_64 127 select ARCH_HAS_PARANOID_L1D_FLUSH 128 select BUILDTIME_TABLE_SORT 129 select CLKEVT_I8253 130 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 131 select CLOCKSOURCE_WATCHDOG 132 select DCACHE_WORD_ACCESS 133 select DYNAMIC_SIGFRAME 134 select EDAC_ATOMIC_SCRUB 135 select EDAC_SUPPORT 136 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 137 select GENERIC_CLOCKEVENTS_MIN_ADJUST 138 select GENERIC_CMOS_UPDATE 139 select GENERIC_CPU_AUTOPROBE 140 select GENERIC_CPU_VULNERABILITIES 141 select GENERIC_EARLY_IOREMAP 142 select GENERIC_ENTRY 143 select GENERIC_IOMAP 144 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 145 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 146 select GENERIC_IRQ_MIGRATION if SMP 147 select GENERIC_IRQ_PROBE 148 select GENERIC_IRQ_RESERVATION_MODE 149 select GENERIC_IRQ_SHOW 150 select GENERIC_PENDING_IRQ if SMP 151 select GENERIC_PTDUMP 152 select GENERIC_SMP_IDLE_THREAD 153 select GENERIC_TIME_VSYSCALL 154 select GENERIC_GETTIMEOFDAY 155 select GENERIC_VDSO_TIME_NS 156 select GUP_GET_PTE_LOW_HIGH if X86_PAE 157 select HARDIRQS_SW_RESEND 158 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 159 select HAVE_ACPI_APEI if ACPI 160 select HAVE_ACPI_APEI_NMI if ACPI 161 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 162 select HAVE_ARCH_AUDITSYSCALL 163 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 164 select HAVE_ARCH_HUGE_VMALLOC if X86_64 165 select HAVE_ARCH_JUMP_LABEL 166 select HAVE_ARCH_JUMP_LABEL_RELATIVE 167 select HAVE_ARCH_KASAN if X86_64 168 select HAVE_ARCH_KASAN_VMALLOC if X86_64 169 select HAVE_ARCH_KFENCE 170 select HAVE_ARCH_KGDB 171 select HAVE_ARCH_MMAP_RND_BITS if MMU 172 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 173 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 174 select HAVE_ARCH_PREL32_RELOCATIONS 175 select HAVE_ARCH_SECCOMP_FILTER 176 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 177 select HAVE_ARCH_STACKLEAK 178 select HAVE_ARCH_TRACEHOOK 179 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 180 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 181 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 182 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 183 select HAVE_ARCH_VMAP_STACK if X86_64 184 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 185 select HAVE_ARCH_WITHIN_STACK_FRAMES 186 select HAVE_ASM_MODVERSIONS 187 select HAVE_CMPXCHG_DOUBLE 188 select HAVE_CMPXCHG_LOCAL 189 select HAVE_CONTEXT_TRACKING if X86_64 190 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING 191 select HAVE_C_RECORDMCOUNT 192 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 193 select HAVE_BUILDTIME_MCOUNT_SORT 194 select HAVE_DEBUG_KMEMLEAK 195 select HAVE_DMA_CONTIGUOUS 196 select HAVE_DYNAMIC_FTRACE 197 select HAVE_DYNAMIC_FTRACE_WITH_REGS 198 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 199 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 200 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 201 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 202 select HAVE_EBPF_JIT 203 select HAVE_EFFICIENT_UNALIGNED_ACCESS 204 select HAVE_EISA 205 select HAVE_EXIT_THREAD 206 select HAVE_FAST_GUP 207 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 208 select HAVE_FTRACE_MCOUNT_RECORD 209 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 210 select HAVE_FUNCTION_TRACER 211 select HAVE_GCC_PLUGINS 212 select HAVE_HW_BREAKPOINT 213 select HAVE_IOREMAP_PROT 214 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 215 select HAVE_IRQ_TIME_ACCOUNTING 216 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 217 select HAVE_KERNEL_BZIP2 218 select HAVE_KERNEL_GZIP 219 select HAVE_KERNEL_LZ4 220 select HAVE_KERNEL_LZMA 221 select HAVE_KERNEL_LZO 222 select HAVE_KERNEL_XZ 223 select HAVE_KERNEL_ZSTD 224 select HAVE_KPROBES 225 select HAVE_KPROBES_ON_FTRACE 226 select HAVE_FUNCTION_ERROR_INJECTION 227 select HAVE_KRETPROBES 228 select HAVE_RETHOOK 229 select HAVE_KVM 230 select HAVE_LIVEPATCH if X86_64 231 select HAVE_MIXED_BREAKPOINTS_REGS 232 select HAVE_MOD_ARCH_SPECIFIC 233 select HAVE_MOVE_PMD 234 select HAVE_MOVE_PUD 235 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 236 select HAVE_NMI 237 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 238 select HAVE_OBJTOOL if X86_64 239 select HAVE_OPTPROBES 240 select HAVE_PCSPKR_PLATFORM 241 select HAVE_PERF_EVENTS 242 select HAVE_PERF_EVENTS_NMI 243 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 244 select HAVE_PCI 245 select HAVE_PERF_REGS 246 select HAVE_PERF_USER_STACK_DUMP 247 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 248 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 249 select HAVE_REGS_AND_STACK_ACCESS_API 250 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 251 select HAVE_FUNCTION_ARG_ACCESS_API 252 select HAVE_SETUP_PER_CPU_AREA 253 select HAVE_SOFTIRQ_ON_OWN_STACK 254 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 255 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 256 select HAVE_STATIC_CALL 257 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 258 select HAVE_PREEMPT_DYNAMIC_CALL 259 select HAVE_RSEQ 260 select HAVE_SYSCALL_TRACEPOINTS 261 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 262 select HAVE_UNSTABLE_SCHED_CLOCK 263 select HAVE_USER_RETURN_NOTIFIER 264 select HAVE_GENERIC_VDSO 265 select HOTPLUG_SMT if SMP 266 select IRQ_FORCED_THREADING 267 select NEED_PER_CPU_EMBED_FIRST_CHUNK 268 select NEED_PER_CPU_PAGE_FIRST_CHUNK 269 select NEED_SG_DMA_LENGTH 270 select PCI_DOMAINS if PCI 271 select PCI_LOCKLESS_CONFIG if PCI 272 select PERF_EVENTS 273 select RTC_LIB 274 select RTC_MC146818_LIB 275 select SPARSE_IRQ 276 select SRCU 277 select SYSCTL_EXCEPTION_TRACE 278 select THREAD_INFO_IN_TASK 279 select TRACE_IRQFLAGS_SUPPORT 280 select USER_STACKTRACE_SUPPORT 281 select VIRT_TO_BUS 282 select HAVE_ARCH_KCSAN if X86_64 283 select X86_FEATURE_NAMES if PROC_FS 284 select PROC_PID_ARCH_STATUS if PROC_FS 285 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 286 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 287 288config INSTRUCTION_DECODER 289 def_bool y 290 depends on KPROBES || PERF_EVENTS || UPROBES 291 292config OUTPUT_FORMAT 293 string 294 default "elf32-i386" if X86_32 295 default "elf64-x86-64" if X86_64 296 297config LOCKDEP_SUPPORT 298 def_bool y 299 300config STACKTRACE_SUPPORT 301 def_bool y 302 303config MMU 304 def_bool y 305 306config ARCH_MMAP_RND_BITS_MIN 307 default 28 if 64BIT 308 default 8 309 310config ARCH_MMAP_RND_BITS_MAX 311 default 32 if 64BIT 312 default 16 313 314config ARCH_MMAP_RND_COMPAT_BITS_MIN 315 default 8 316 317config ARCH_MMAP_RND_COMPAT_BITS_MAX 318 default 16 319 320config SBUS 321 bool 322 323config GENERIC_ISA_DMA 324 def_bool y 325 depends on ISA_DMA_API 326 327config GENERIC_BUG 328 def_bool y 329 depends on BUG 330 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 331 332config GENERIC_BUG_RELATIVE_POINTERS 333 bool 334 335config ARCH_MAY_HAVE_PC_FDC 336 def_bool y 337 depends on ISA_DMA_API 338 339config GENERIC_CALIBRATE_DELAY 340 def_bool y 341 342config ARCH_HAS_CPU_RELAX 343 def_bool y 344 345config ARCH_HIBERNATION_POSSIBLE 346 def_bool y 347 348config ARCH_NR_GPIO 349 int 350 default 1024 if X86_64 351 default 512 352 353config ARCH_SUSPEND_POSSIBLE 354 def_bool y 355 356config AUDIT_ARCH 357 def_bool y if X86_64 358 359config KASAN_SHADOW_OFFSET 360 hex 361 depends on KASAN 362 default 0xdffffc0000000000 363 364config HAVE_INTEL_TXT 365 def_bool y 366 depends on INTEL_IOMMU && ACPI 367 368config X86_32_SMP 369 def_bool y 370 depends on X86_32 && SMP 371 372config X86_64_SMP 373 def_bool y 374 depends on X86_64 && SMP 375 376config ARCH_SUPPORTS_UPROBES 377 def_bool y 378 379config FIX_EARLYCON_MEM 380 def_bool y 381 382config DYNAMIC_PHYSICAL_MASK 383 bool 384 385config PGTABLE_LEVELS 386 int 387 default 5 if X86_5LEVEL 388 default 4 if X86_64 389 default 3 if X86_PAE 390 default 2 391 392config CC_HAS_SANE_STACKPROTECTOR 393 bool 394 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT 395 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC)) 396 help 397 We have to make sure stack protector is unconditionally disabled if 398 the compiler produces broken code or if it does not let us control 399 the segment on 32-bit kernels. 400 401menu "Processor type and features" 402 403config SMP 404 bool "Symmetric multi-processing support" 405 help 406 This enables support for systems with more than one CPU. If you have 407 a system with only one CPU, say N. If you have a system with more 408 than one CPU, say Y. 409 410 If you say N here, the kernel will run on uni- and multiprocessor 411 machines, but will use only one CPU of a multiprocessor machine. If 412 you say Y here, the kernel will run on many, but not all, 413 uniprocessor machines. On a uniprocessor machine, the kernel 414 will run faster if you say N here. 415 416 Note that if you say Y here and choose architecture "586" or 417 "Pentium" under "Processor family", the kernel will not work on 486 418 architectures. Similarly, multiprocessor kernels for the "PPro" 419 architecture may not work on all Pentium based boards. 420 421 People using multiprocessor machines who say Y here should also say 422 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 423 Management" code will be disabled if you say Y here. 424 425 See also <file:Documentation/x86/i386/IO-APIC.rst>, 426 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 427 <http://www.tldp.org/docs.html#howto>. 428 429 If you don't know what to do here, say N. 430 431config X86_FEATURE_NAMES 432 bool "Processor feature human-readable names" if EMBEDDED 433 default y 434 help 435 This option compiles in a table of x86 feature bits and corresponding 436 names. This is required to support /proc/cpuinfo and a few kernel 437 messages. You can disable this to save space, at the expense of 438 making those few kernel messages show numeric feature bits instead. 439 440 If in doubt, say Y. 441 442config X86_X2APIC 443 bool "Support x2apic" 444 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 445 help 446 This enables x2apic support on CPUs that have this feature. 447 448 This allows 32-bit apic IDs (so it can support very large systems), 449 and accesses the local apic via MSRs not via mmio. 450 451 If you don't know what to do here, say N. 452 453config X86_MPPARSE 454 bool "Enable MPS table" if ACPI 455 default y 456 depends on X86_LOCAL_APIC 457 help 458 For old smp systems that do not have proper acpi support. Newer systems 459 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 460 461config GOLDFISH 462 def_bool y 463 depends on X86_GOLDFISH 464 465config RETPOLINE 466 bool "Avoid speculative indirect branches in kernel" 467 select OBJTOOL if HAVE_OBJTOOL 468 default y 469 help 470 Compile kernel with the retpoline compiler options to guard against 471 kernel-to-user data leaks by avoiding speculative indirect 472 branches. Requires a compiler with -mindirect-branch=thunk-extern 473 support for full protection. The kernel may run slower. 474 475config CC_HAS_SLS 476 def_bool $(cc-option,-mharden-sls=all) 477 478config SLS 479 bool "Mitigate Straight-Line-Speculation" 480 depends on CC_HAS_SLS && X86_64 481 select OBJTOOL if HAVE_OBJTOOL 482 default n 483 help 484 Compile the kernel with straight-line-speculation options to guard 485 against straight line speculation. The kernel image might be slightly 486 larger. 487 488config X86_CPU_RESCTRL 489 bool "x86 CPU resource control support" 490 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 491 select KERNFS 492 select PROC_CPU_RESCTRL if PROC_FS 493 help 494 Enable x86 CPU resource control support. 495 496 Provide support for the allocation and monitoring of system resources 497 usage by the CPU. 498 499 Intel calls this Intel Resource Director Technology 500 (Intel(R) RDT). More information about RDT can be found in the 501 Intel x86 Architecture Software Developer Manual. 502 503 AMD calls this AMD Platform Quality of Service (AMD QoS). 504 More information about AMD QoS can be found in the AMD64 Technology 505 Platform Quality of Service Extensions manual. 506 507 Say N if unsure. 508 509if X86_32 510config X86_BIGSMP 511 bool "Support for big SMP systems with more than 8 CPUs" 512 depends on SMP 513 help 514 This option is needed for the systems that have more than 8 CPUs. 515 516config X86_EXTENDED_PLATFORM 517 bool "Support for extended (non-PC) x86 platforms" 518 default y 519 help 520 If you disable this option then the kernel will only support 521 standard PC platforms. (which covers the vast majority of 522 systems out there.) 523 524 If you enable this option then you'll be able to select support 525 for the following (non-PC) 32 bit x86 platforms: 526 Goldfish (Android emulator) 527 AMD Elan 528 RDC R-321x SoC 529 SGI 320/540 (Visual Workstation) 530 STA2X11-based (e.g. Northville) 531 Moorestown MID devices 532 533 If you have one of these systems, or if you want to build a 534 generic distribution kernel, say Y here - otherwise say N. 535endif # X86_32 536 537if X86_64 538config X86_EXTENDED_PLATFORM 539 bool "Support for extended (non-PC) x86 platforms" 540 default y 541 help 542 If you disable this option then the kernel will only support 543 standard PC platforms. (which covers the vast majority of 544 systems out there.) 545 546 If you enable this option then you'll be able to select support 547 for the following (non-PC) 64 bit x86 platforms: 548 Numascale NumaChip 549 ScaleMP vSMP 550 SGI Ultraviolet 551 552 If you have one of these systems, or if you want to build a 553 generic distribution kernel, say Y here - otherwise say N. 554endif # X86_64 555# This is an alphabetically sorted list of 64 bit extended platforms 556# Please maintain the alphabetic order if and when there are additions 557config X86_NUMACHIP 558 bool "Numascale NumaChip" 559 depends on X86_64 560 depends on X86_EXTENDED_PLATFORM 561 depends on NUMA 562 depends on SMP 563 depends on X86_X2APIC 564 depends on PCI_MMCONFIG 565 help 566 Adds support for Numascale NumaChip large-SMP systems. Needed to 567 enable more than ~168 cores. 568 If you don't have one of these, you should say N here. 569 570config X86_VSMP 571 bool "ScaleMP vSMP" 572 select HYPERVISOR_GUEST 573 select PARAVIRT 574 depends on X86_64 && PCI 575 depends on X86_EXTENDED_PLATFORM 576 depends on SMP 577 help 578 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 579 supposed to run on these EM64T-based machines. Only choose this option 580 if you have one of these machines. 581 582config X86_UV 583 bool "SGI Ultraviolet" 584 depends on X86_64 585 depends on X86_EXTENDED_PLATFORM 586 depends on NUMA 587 depends on EFI 588 depends on KEXEC_CORE 589 depends on X86_X2APIC 590 depends on PCI 591 help 592 This option is needed in order to support SGI Ultraviolet systems. 593 If you don't have one of these, you should say N here. 594 595# Following is an alphabetically sorted list of 32 bit extended platforms 596# Please maintain the alphabetic order if and when there are additions 597 598config X86_GOLDFISH 599 bool "Goldfish (Virtual Platform)" 600 depends on X86_EXTENDED_PLATFORM 601 help 602 Enable support for the Goldfish virtual platform used primarily 603 for Android development. Unless you are building for the Android 604 Goldfish emulator say N here. 605 606config X86_INTEL_CE 607 bool "CE4100 TV platform" 608 depends on PCI 609 depends on PCI_GODIRECT 610 depends on X86_IO_APIC 611 depends on X86_32 612 depends on X86_EXTENDED_PLATFORM 613 select X86_REBOOTFIXUPS 614 select OF 615 select OF_EARLY_FLATTREE 616 help 617 Select for the Intel CE media processor (CE4100) SOC. 618 This option compiles in support for the CE4100 SOC for settop 619 boxes and media devices. 620 621config X86_INTEL_MID 622 bool "Intel MID platform support" 623 depends on X86_EXTENDED_PLATFORM 624 depends on X86_PLATFORM_DEVICES 625 depends on PCI 626 depends on X86_64 || (PCI_GOANY && X86_32) 627 depends on X86_IO_APIC 628 select I2C 629 select DW_APB_TIMER 630 select INTEL_SCU_PCI 631 help 632 Select to build a kernel capable of supporting Intel MID (Mobile 633 Internet Device) platform systems which do not have the PCI legacy 634 interfaces. If you are building for a PC class system say N here. 635 636 Intel MID platforms are based on an Intel processor and chipset which 637 consume less power than most of the x86 derivatives. 638 639config X86_INTEL_QUARK 640 bool "Intel Quark platform support" 641 depends on X86_32 642 depends on X86_EXTENDED_PLATFORM 643 depends on X86_PLATFORM_DEVICES 644 depends on X86_TSC 645 depends on PCI 646 depends on PCI_GOANY 647 depends on X86_IO_APIC 648 select IOSF_MBI 649 select INTEL_IMR 650 select COMMON_CLK 651 help 652 Select to include support for Quark X1000 SoC. 653 Say Y here if you have a Quark based system such as the Arduino 654 compatible Intel Galileo. 655 656config X86_INTEL_LPSS 657 bool "Intel Low Power Subsystem Support" 658 depends on X86 && ACPI && PCI 659 select COMMON_CLK 660 select PINCTRL 661 select IOSF_MBI 662 help 663 Select to build support for Intel Low Power Subsystem such as 664 found on Intel Lynxpoint PCH. Selecting this option enables 665 things like clock tree (common clock framework) and pincontrol 666 which are needed by the LPSS peripheral drivers. 667 668config X86_AMD_PLATFORM_DEVICE 669 bool "AMD ACPI2Platform devices support" 670 depends on ACPI 671 select COMMON_CLK 672 select PINCTRL 673 help 674 Select to interpret AMD specific ACPI device to platform device 675 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 676 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 677 implemented under PINCTRL subsystem. 678 679config IOSF_MBI 680 tristate "Intel SoC IOSF Sideband support for SoC platforms" 681 depends on PCI 682 help 683 This option enables sideband register access support for Intel SoC 684 platforms. On these platforms the IOSF sideband is used in lieu of 685 MSR's for some register accesses, mostly but not limited to thermal 686 and power. Drivers may query the availability of this device to 687 determine if they need the sideband in order to work on these 688 platforms. The sideband is available on the following SoC products. 689 This list is not meant to be exclusive. 690 - BayTrail 691 - Braswell 692 - Quark 693 694 You should say Y if you are running a kernel on one of these SoC's. 695 696config IOSF_MBI_DEBUG 697 bool "Enable IOSF sideband access through debugfs" 698 depends on IOSF_MBI && DEBUG_FS 699 help 700 Select this option to expose the IOSF sideband access registers (MCR, 701 MDR, MCRX) through debugfs to write and read register information from 702 different units on the SoC. This is most useful for obtaining device 703 state information for debug and analysis. As this is a general access 704 mechanism, users of this option would have specific knowledge of the 705 device they want to access. 706 707 If you don't require the option or are in doubt, say N. 708 709config X86_RDC321X 710 bool "RDC R-321x SoC" 711 depends on X86_32 712 depends on X86_EXTENDED_PLATFORM 713 select M486 714 select X86_REBOOTFIXUPS 715 help 716 This option is needed for RDC R-321x system-on-chip, also known 717 as R-8610-(G). 718 If you don't have one of these chips, you should say N here. 719 720config X86_32_NON_STANDARD 721 bool "Support non-standard 32-bit SMP architectures" 722 depends on X86_32 && SMP 723 depends on X86_EXTENDED_PLATFORM 724 help 725 This option compiles in the bigsmp and STA2X11 default 726 subarchitectures. It is intended for a generic binary 727 kernel. If you select them all, kernel will probe it one by 728 one and will fallback to default. 729 730# Alphabetically sorted list of Non standard 32 bit platforms 731 732config X86_SUPPORTS_MEMORY_FAILURE 733 def_bool y 734 # MCE code calls memory_failure(): 735 depends on X86_MCE 736 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 737 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 738 depends on X86_64 || !SPARSEMEM 739 select ARCH_SUPPORTS_MEMORY_FAILURE 740 741config STA2X11 742 bool "STA2X11 Companion Chip Support" 743 depends on X86_32_NON_STANDARD && PCI 744 select SWIOTLB 745 select MFD_STA2X11 746 select GPIOLIB 747 help 748 This adds support for boards based on the STA2X11 IO-Hub, 749 a.k.a. "ConneXt". The chip is used in place of the standard 750 PC chipset, so all "standard" peripherals are missing. If this 751 option is selected the kernel will still be able to boot on 752 standard PC machines. 753 754config X86_32_IRIS 755 tristate "Eurobraille/Iris poweroff module" 756 depends on X86_32 757 help 758 The Iris machines from EuroBraille do not have APM or ACPI support 759 to shut themselves down properly. A special I/O sequence is 760 needed to do so, which is what this module does at 761 kernel shutdown. 762 763 This is only for Iris machines from EuroBraille. 764 765 If unused, say N. 766 767config SCHED_OMIT_FRAME_POINTER 768 def_bool y 769 prompt "Single-depth WCHAN output" 770 depends on X86 771 help 772 Calculate simpler /proc/<PID>/wchan values. If this option 773 is disabled then wchan values will recurse back to the 774 caller function. This provides more accurate wchan values, 775 at the expense of slightly more scheduling overhead. 776 777 If in doubt, say "Y". 778 779menuconfig HYPERVISOR_GUEST 780 bool "Linux guest support" 781 help 782 Say Y here to enable options for running Linux under various hyper- 783 visors. This option enables basic hypervisor detection and platform 784 setup. 785 786 If you say N, all options in this submenu will be skipped and 787 disabled, and Linux guest support won't be built in. 788 789if HYPERVISOR_GUEST 790 791config PARAVIRT 792 bool "Enable paravirtualization code" 793 depends on HAVE_STATIC_CALL 794 help 795 This changes the kernel so it can modify itself when it is run 796 under a hypervisor, potentially improving performance significantly 797 over full virtualization. However, when run without a hypervisor 798 the kernel is theoretically slower and slightly larger. 799 800config PARAVIRT_XXL 801 bool 802 803config PARAVIRT_DEBUG 804 bool "paravirt-ops debugging" 805 depends on PARAVIRT && DEBUG_KERNEL 806 help 807 Enable to debug paravirt_ops internals. Specifically, BUG if 808 a paravirt_op is missing when it is called. 809 810config PARAVIRT_SPINLOCKS 811 bool "Paravirtualization layer for spinlocks" 812 depends on PARAVIRT && SMP 813 help 814 Paravirtualized spinlocks allow a pvops backend to replace the 815 spinlock implementation with something virtualization-friendly 816 (for example, block the virtual CPU rather than spinning). 817 818 It has a minimal impact on native kernels and gives a nice performance 819 benefit on paravirtualized KVM / Xen kernels. 820 821 If you are unsure how to answer this question, answer Y. 822 823config X86_HV_CALLBACK_VECTOR 824 def_bool n 825 826source "arch/x86/xen/Kconfig" 827 828config KVM_GUEST 829 bool "KVM Guest support (including kvmclock)" 830 depends on PARAVIRT 831 select PARAVIRT_CLOCK 832 select ARCH_CPUIDLE_HALTPOLL 833 select X86_HV_CALLBACK_VECTOR 834 default y 835 help 836 This option enables various optimizations for running under the KVM 837 hypervisor. It includes a paravirtualized clock, so that instead 838 of relying on a PIT (or probably other) emulation by the 839 underlying device model, the host provides the guest with 840 timing infrastructure such as time of day, and system time 841 842config ARCH_CPUIDLE_HALTPOLL 843 def_bool n 844 prompt "Disable host haltpoll when loading haltpoll driver" 845 help 846 If virtualized under KVM, disable host haltpoll. 847 848config PVH 849 bool "Support for running PVH guests" 850 help 851 This option enables the PVH entry point for guest virtual machines 852 as specified in the x86/HVM direct boot ABI. 853 854config PARAVIRT_TIME_ACCOUNTING 855 bool "Paravirtual steal time accounting" 856 depends on PARAVIRT 857 help 858 Select this option to enable fine granularity task steal time 859 accounting. Time spent executing other tasks in parallel with 860 the current vCPU is discounted from the vCPU power. To account for 861 that, there can be a small performance impact. 862 863 If in doubt, say N here. 864 865config PARAVIRT_CLOCK 866 bool 867 868config JAILHOUSE_GUEST 869 bool "Jailhouse non-root cell support" 870 depends on X86_64 && PCI 871 select X86_PM_TIMER 872 help 873 This option allows to run Linux as guest in a Jailhouse non-root 874 cell. You can leave this option disabled if you only want to start 875 Jailhouse and run Linux afterwards in the root cell. 876 877config ACRN_GUEST 878 bool "ACRN Guest support" 879 depends on X86_64 880 select X86_HV_CALLBACK_VECTOR 881 help 882 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 883 a flexible, lightweight reference open-source hypervisor, built with 884 real-time and safety-criticality in mind. It is built for embedded 885 IOT with small footprint and real-time features. More details can be 886 found in https://projectacrn.org/. 887 888config INTEL_TDX_GUEST 889 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 890 depends on X86_64 && CPU_SUP_INTEL 891 depends on X86_X2APIC 892 select ARCH_HAS_CC_PLATFORM 893 select X86_MEM_ENCRYPT 894 select X86_MCE 895 help 896 Support running as a guest under Intel TDX. Without this support, 897 the guest kernel can not boot or run under TDX. 898 TDX includes memory encryption and integrity capabilities 899 which protect the confidentiality and integrity of guest 900 memory contents and CPU state. TDX guests are protected from 901 some attacks from the VMM. 902 903endif # HYPERVISOR_GUEST 904 905source "arch/x86/Kconfig.cpu" 906 907config HPET_TIMER 908 def_bool X86_64 909 prompt "HPET Timer Support" if X86_32 910 help 911 Use the IA-PC HPET (High Precision Event Timer) to manage 912 time in preference to the PIT and RTC, if a HPET is 913 present. 914 HPET is the next generation timer replacing legacy 8254s. 915 The HPET provides a stable time base on SMP 916 systems, unlike the TSC, but it is more expensive to access, 917 as it is off-chip. The interface used is documented 918 in the HPET spec, revision 1. 919 920 You can safely choose Y here. However, HPET will only be 921 activated if the platform and the BIOS support this feature. 922 Otherwise the 8254 will be used for timing services. 923 924 Choose N to continue using the legacy 8254 timer. 925 926config HPET_EMULATE_RTC 927 def_bool y 928 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 929 930# Mark as expert because too many people got it wrong. 931# The code disables itself when not needed. 932config DMI 933 default y 934 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 935 bool "Enable DMI scanning" if EXPERT 936 help 937 Enabled scanning of DMI to identify machine quirks. Say Y 938 here unless you have verified that your setup is not 939 affected by entries in the DMI blacklist. Required by PNP 940 BIOS code. 941 942config GART_IOMMU 943 bool "Old AMD GART IOMMU support" 944 select DMA_OPS 945 select IOMMU_HELPER 946 select SWIOTLB 947 depends on X86_64 && PCI && AMD_NB 948 help 949 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 950 GART based hardware IOMMUs. 951 952 The GART supports full DMA access for devices with 32-bit access 953 limitations, on systems with more than 3 GB. This is usually needed 954 for USB, sound, many IDE/SATA chipsets and some other devices. 955 956 Newer systems typically have a modern AMD IOMMU, supported via 957 the CONFIG_AMD_IOMMU=y config option. 958 959 In normal configurations this driver is only active when needed: 960 there's more than 3 GB of memory and the system contains a 961 32-bit limited device. 962 963 If unsure, say Y. 964 965config BOOT_VESA_SUPPORT 966 bool 967 help 968 If true, at least one selected framebuffer driver can take advantage 969 of VESA video modes set at an early boot stage via the vga= parameter. 970 971config MAXSMP 972 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 973 depends on X86_64 && SMP && DEBUG_KERNEL 974 select CPUMASK_OFFSTACK 975 help 976 Enable maximum number of CPUS and NUMA Nodes for this architecture. 977 If unsure, say N. 978 979# 980# The maximum number of CPUs supported: 981# 982# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 983# and which can be configured interactively in the 984# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 985# 986# The ranges are different on 32-bit and 64-bit kernels, depending on 987# hardware capabilities and scalability features of the kernel. 988# 989# ( If MAXSMP is enabled we just use the highest possible value and disable 990# interactive configuration. ) 991# 992 993config NR_CPUS_RANGE_BEGIN 994 int 995 default NR_CPUS_RANGE_END if MAXSMP 996 default 1 if !SMP 997 default 2 998 999config NR_CPUS_RANGE_END 1000 int 1001 depends on X86_32 1002 default 64 if SMP && X86_BIGSMP 1003 default 8 if SMP && !X86_BIGSMP 1004 default 1 if !SMP 1005 1006config NR_CPUS_RANGE_END 1007 int 1008 depends on X86_64 1009 default 8192 if SMP && CPUMASK_OFFSTACK 1010 default 512 if SMP && !CPUMASK_OFFSTACK 1011 default 1 if !SMP 1012 1013config NR_CPUS_DEFAULT 1014 int 1015 depends on X86_32 1016 default 32 if X86_BIGSMP 1017 default 8 if SMP 1018 default 1 if !SMP 1019 1020config NR_CPUS_DEFAULT 1021 int 1022 depends on X86_64 1023 default 8192 if MAXSMP 1024 default 64 if SMP 1025 default 1 if !SMP 1026 1027config NR_CPUS 1028 int "Maximum number of CPUs" if SMP && !MAXSMP 1029 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1030 default NR_CPUS_DEFAULT 1031 help 1032 This allows you to specify the maximum number of CPUs which this 1033 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1034 supported value is 8192, otherwise the maximum value is 512. The 1035 minimum value which makes sense is 2. 1036 1037 This is purely to save memory: each supported CPU adds about 8KB 1038 to the kernel image. 1039 1040config SCHED_CLUSTER 1041 bool "Cluster scheduler support" 1042 depends on SMP 1043 default y 1044 help 1045 Cluster scheduler support improves the CPU scheduler's decision 1046 making when dealing with machines that have clusters of CPUs. 1047 Cluster usually means a couple of CPUs which are placed closely 1048 by sharing mid-level caches, last-level cache tags or internal 1049 busses. 1050 1051config SCHED_SMT 1052 def_bool y if SMP 1053 1054config SCHED_MC 1055 def_bool y 1056 prompt "Multi-core scheduler support" 1057 depends on SMP 1058 help 1059 Multi-core scheduler support improves the CPU scheduler's decision 1060 making when dealing with multi-core CPU chips at a cost of slightly 1061 increased overhead in some places. If unsure say N here. 1062 1063config SCHED_MC_PRIO 1064 bool "CPU core priorities scheduler support" 1065 depends on SCHED_MC && CPU_SUP_INTEL 1066 select X86_INTEL_PSTATE 1067 select CPU_FREQ 1068 default y 1069 help 1070 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1071 core ordering determined at manufacturing time, which allows 1072 certain cores to reach higher turbo frequencies (when running 1073 single threaded workloads) than others. 1074 1075 Enabling this kernel feature teaches the scheduler about 1076 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1077 scheduler's CPU selection logic accordingly, so that higher 1078 overall system performance can be achieved. 1079 1080 This feature will have no effect on CPUs without this feature. 1081 1082 If unsure say Y here. 1083 1084config UP_LATE_INIT 1085 def_bool y 1086 depends on !SMP && X86_LOCAL_APIC 1087 1088config X86_UP_APIC 1089 bool "Local APIC support on uniprocessors" if !PCI_MSI 1090 default PCI_MSI 1091 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1092 help 1093 A local APIC (Advanced Programmable Interrupt Controller) is an 1094 integrated interrupt controller in the CPU. If you have a single-CPU 1095 system which has a processor with a local APIC, you can say Y here to 1096 enable and use it. If you say Y here even though your machine doesn't 1097 have a local APIC, then the kernel will still run with no slowdown at 1098 all. The local APIC supports CPU-generated self-interrupts (timer, 1099 performance counters), and the NMI watchdog which detects hard 1100 lockups. 1101 1102config X86_UP_IOAPIC 1103 bool "IO-APIC support on uniprocessors" 1104 depends on X86_UP_APIC 1105 help 1106 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1107 SMP-capable replacement for PC-style interrupt controllers. Most 1108 SMP systems and many recent uniprocessor systems have one. 1109 1110 If you have a single-CPU system with an IO-APIC, you can say Y here 1111 to use it. If you say Y here even though your machine doesn't have 1112 an IO-APIC, then the kernel will still run with no slowdown at all. 1113 1114config X86_LOCAL_APIC 1115 def_bool y 1116 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1117 select IRQ_DOMAIN_HIERARCHY 1118 select PCI_MSI_IRQ_DOMAIN if PCI_MSI 1119 1120config X86_IO_APIC 1121 def_bool y 1122 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1123 1124config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1125 bool "Reroute for broken boot IRQs" 1126 depends on X86_IO_APIC 1127 help 1128 This option enables a workaround that fixes a source of 1129 spurious interrupts. This is recommended when threaded 1130 interrupt handling is used on systems where the generation of 1131 superfluous "boot interrupts" cannot be disabled. 1132 1133 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1134 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1135 kernel does during interrupt handling). On chipsets where this 1136 boot IRQ generation cannot be disabled, this workaround keeps 1137 the original IRQ line masked so that only the equivalent "boot 1138 IRQ" is delivered to the CPUs. The workaround also tells the 1139 kernel to set up the IRQ handler on the boot IRQ line. In this 1140 way only one interrupt is delivered to the kernel. Otherwise 1141 the spurious second interrupt may cause the kernel to bring 1142 down (vital) interrupt lines. 1143 1144 Only affects "broken" chipsets. Interrupt sharing may be 1145 increased on these systems. 1146 1147config X86_MCE 1148 bool "Machine Check / overheating reporting" 1149 select GENERIC_ALLOCATOR 1150 default y 1151 help 1152 Machine Check support allows the processor to notify the 1153 kernel if it detects a problem (e.g. overheating, data corruption). 1154 The action the kernel takes depends on the severity of the problem, 1155 ranging from warning messages to halting the machine. 1156 1157config X86_MCELOG_LEGACY 1158 bool "Support for deprecated /dev/mcelog character device" 1159 depends on X86_MCE 1160 help 1161 Enable support for /dev/mcelog which is needed by the old mcelog 1162 userspace logging daemon. Consider switching to the new generation 1163 rasdaemon solution. 1164 1165config X86_MCE_INTEL 1166 def_bool y 1167 prompt "Intel MCE features" 1168 depends on X86_MCE && X86_LOCAL_APIC 1169 help 1170 Additional support for intel specific MCE features such as 1171 the thermal monitor. 1172 1173config X86_MCE_AMD 1174 def_bool y 1175 prompt "AMD MCE features" 1176 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1177 help 1178 Additional support for AMD specific MCE features such as 1179 the DRAM Error Threshold. 1180 1181config X86_ANCIENT_MCE 1182 bool "Support for old Pentium 5 / WinChip machine checks" 1183 depends on X86_32 && X86_MCE 1184 help 1185 Include support for machine check handling on old Pentium 5 or WinChip 1186 systems. These typically need to be enabled explicitly on the command 1187 line. 1188 1189config X86_MCE_THRESHOLD 1190 depends on X86_MCE_AMD || X86_MCE_INTEL 1191 def_bool y 1192 1193config X86_MCE_INJECT 1194 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1195 tristate "Machine check injector support" 1196 help 1197 Provide support for injecting machine checks for testing purposes. 1198 If you don't know what a machine check is and you don't do kernel 1199 QA it is safe to say n. 1200 1201source "arch/x86/events/Kconfig" 1202 1203config X86_LEGACY_VM86 1204 bool "Legacy VM86 support" 1205 depends on X86_32 1206 help 1207 This option allows user programs to put the CPU into V8086 1208 mode, which is an 80286-era approximation of 16-bit real mode. 1209 1210 Some very old versions of X and/or vbetool require this option 1211 for user mode setting. Similarly, DOSEMU will use it if 1212 available to accelerate real mode DOS programs. However, any 1213 recent version of DOSEMU, X, or vbetool should be fully 1214 functional even without kernel VM86 support, as they will all 1215 fall back to software emulation. Nevertheless, if you are using 1216 a 16-bit DOS program where 16-bit performance matters, vm86 1217 mode might be faster than emulation and you might want to 1218 enable this option. 1219 1220 Note that any app that works on a 64-bit kernel is unlikely to 1221 need this option, as 64-bit kernels don't, and can't, support 1222 V8086 mode. This option is also unrelated to 16-bit protected 1223 mode and is not needed to run most 16-bit programs under Wine. 1224 1225 Enabling this option increases the complexity of the kernel 1226 and slows down exception handling a tiny bit. 1227 1228 If unsure, say N here. 1229 1230config VM86 1231 bool 1232 default X86_LEGACY_VM86 1233 1234config X86_16BIT 1235 bool "Enable support for 16-bit segments" if EXPERT 1236 default y 1237 depends on MODIFY_LDT_SYSCALL 1238 help 1239 This option is required by programs like Wine to run 16-bit 1240 protected mode legacy code on x86 processors. Disabling 1241 this option saves about 300 bytes on i386, or around 6K text 1242 plus 16K runtime memory on x86-64, 1243 1244config X86_ESPFIX32 1245 def_bool y 1246 depends on X86_16BIT && X86_32 1247 1248config X86_ESPFIX64 1249 def_bool y 1250 depends on X86_16BIT && X86_64 1251 1252config X86_VSYSCALL_EMULATION 1253 bool "Enable vsyscall emulation" if EXPERT 1254 default y 1255 depends on X86_64 1256 help 1257 This enables emulation of the legacy vsyscall page. Disabling 1258 it is roughly equivalent to booting with vsyscall=none, except 1259 that it will also disable the helpful warning if a program 1260 tries to use a vsyscall. With this option set to N, offending 1261 programs will just segfault, citing addresses of the form 1262 0xffffffffff600?00. 1263 1264 This option is required by many programs built before 2013, and 1265 care should be used even with newer programs if set to N. 1266 1267 Disabling this option saves about 7K of kernel size and 1268 possibly 4K of additional runtime pagetable memory. 1269 1270config X86_IOPL_IOPERM 1271 bool "IOPERM and IOPL Emulation" 1272 default y 1273 help 1274 This enables the ioperm() and iopl() syscalls which are necessary 1275 for legacy applications. 1276 1277 Legacy IOPL support is an overbroad mechanism which allows user 1278 space aside of accessing all 65536 I/O ports also to disable 1279 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1280 capabilities and permission from potentially active security 1281 modules. 1282 1283 The emulation restricts the functionality of the syscall to 1284 only allowing the full range I/O port access, but prevents the 1285 ability to disable interrupts from user space which would be 1286 granted if the hardware IOPL mechanism would be used. 1287 1288config TOSHIBA 1289 tristate "Toshiba Laptop support" 1290 depends on X86_32 1291 help 1292 This adds a driver to safely access the System Management Mode of 1293 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1294 not work on models with a Phoenix BIOS. The System Management Mode 1295 is used to set the BIOS and power saving options on Toshiba portables. 1296 1297 For information on utilities to make use of this driver see the 1298 Toshiba Linux utilities web site at: 1299 <http://www.buzzard.org.uk/toshiba/>. 1300 1301 Say Y if you intend to run this kernel on a Toshiba portable. 1302 Say N otherwise. 1303 1304config X86_REBOOTFIXUPS 1305 bool "Enable X86 board specific fixups for reboot" 1306 depends on X86_32 1307 help 1308 This enables chipset and/or board specific fixups to be done 1309 in order to get reboot to work correctly. This is only needed on 1310 some combinations of hardware and BIOS. The symptom, for which 1311 this config is intended, is when reboot ends with a stalled/hung 1312 system. 1313 1314 Currently, the only fixup is for the Geode machines using 1315 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1316 1317 Say Y if you want to enable the fixup. Currently, it's safe to 1318 enable this option even if you don't need it. 1319 Say N otherwise. 1320 1321config MICROCODE 1322 bool "CPU microcode loading support" 1323 default y 1324 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1325 help 1326 If you say Y here, you will be able to update the microcode on 1327 Intel and AMD processors. The Intel support is for the IA32 family, 1328 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1329 AMD support is for families 0x10 and later. You will obviously need 1330 the actual microcode binary data itself which is not shipped with 1331 the Linux kernel. 1332 1333 The preferred method to load microcode from a detached initrd is described 1334 in Documentation/x86/microcode.rst. For that you need to enable 1335 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1336 initrd for microcode blobs. 1337 1338 In addition, you can build the microcode into the kernel. For that you 1339 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1340 config option. 1341 1342config MICROCODE_INTEL 1343 bool "Intel microcode loading support" 1344 depends on CPU_SUP_INTEL && MICROCODE 1345 default MICROCODE 1346 help 1347 This options enables microcode patch loading support for Intel 1348 processors. 1349 1350 For the current Intel microcode data package go to 1351 <https://downloadcenter.intel.com> and search for 1352 'Linux Processor Microcode Data File'. 1353 1354config MICROCODE_AMD 1355 bool "AMD microcode loading support" 1356 depends on CPU_SUP_AMD && MICROCODE 1357 help 1358 If you select this option, microcode patch loading support for AMD 1359 processors will be enabled. 1360 1361config MICROCODE_LATE_LOADING 1362 bool "Late microcode loading (DANGEROUS)" 1363 default n 1364 depends on MICROCODE 1365 help 1366 Loading microcode late, when the system is up and executing instructions 1367 is a tricky business and should be avoided if possible. Just the sequence 1368 of synchronizing all cores and SMT threads is one fragile dance which does 1369 not guarantee that cores might not softlock after the loading. Therefore, 1370 use this at your own risk. Late loading taints the kernel too. 1371 1372config X86_MSR 1373 tristate "/dev/cpu/*/msr - Model-specific register support" 1374 help 1375 This device gives privileged processes access to the x86 1376 Model-Specific Registers (MSRs). It is a character device with 1377 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1378 MSR accesses are directed to a specific CPU on multi-processor 1379 systems. 1380 1381config X86_CPUID 1382 tristate "/dev/cpu/*/cpuid - CPU information support" 1383 help 1384 This device gives processes access to the x86 CPUID instruction to 1385 be executed on a specific processor. It is a character device 1386 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1387 /dev/cpu/31/cpuid. 1388 1389choice 1390 prompt "High Memory Support" 1391 default HIGHMEM4G 1392 depends on X86_32 1393 1394config NOHIGHMEM 1395 bool "off" 1396 help 1397 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1398 However, the address space of 32-bit x86 processors is only 4 1399 Gigabytes large. That means that, if you have a large amount of 1400 physical memory, not all of it can be "permanently mapped" by the 1401 kernel. The physical memory that's not permanently mapped is called 1402 "high memory". 1403 1404 If you are compiling a kernel which will never run on a machine with 1405 more than 1 Gigabyte total physical RAM, answer "off" here (default 1406 choice and suitable for most users). This will result in a "3GB/1GB" 1407 split: 3GB are mapped so that each process sees a 3GB virtual memory 1408 space and the remaining part of the 4GB virtual memory space is used 1409 by the kernel to permanently map as much physical memory as 1410 possible. 1411 1412 If the machine has between 1 and 4 Gigabytes physical RAM, then 1413 answer "4GB" here. 1414 1415 If more than 4 Gigabytes is used then answer "64GB" here. This 1416 selection turns Intel PAE (Physical Address Extension) mode on. 1417 PAE implements 3-level paging on IA32 processors. PAE is fully 1418 supported by Linux, PAE mode is implemented on all recent Intel 1419 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1420 then the kernel will not boot on CPUs that don't support PAE! 1421 1422 The actual amount of total physical memory will either be 1423 auto detected or can be forced by using a kernel command line option 1424 such as "mem=256M". (Try "man bootparam" or see the documentation of 1425 your boot loader (lilo or loadlin) about how to pass options to the 1426 kernel at boot time.) 1427 1428 If unsure, say "off". 1429 1430config HIGHMEM4G 1431 bool "4GB" 1432 help 1433 Select this if you have a 32-bit processor and between 1 and 4 1434 gigabytes of physical RAM. 1435 1436config HIGHMEM64G 1437 bool "64GB" 1438 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1439 select X86_PAE 1440 help 1441 Select this if you have a 32-bit processor and more than 4 1442 gigabytes of physical RAM. 1443 1444endchoice 1445 1446choice 1447 prompt "Memory split" if EXPERT 1448 default VMSPLIT_3G 1449 depends on X86_32 1450 help 1451 Select the desired split between kernel and user memory. 1452 1453 If the address range available to the kernel is less than the 1454 physical memory installed, the remaining memory will be available 1455 as "high memory". Accessing high memory is a little more costly 1456 than low memory, as it needs to be mapped into the kernel first. 1457 Note that increasing the kernel address space limits the range 1458 available to user programs, making the address space there 1459 tighter. Selecting anything other than the default 3G/1G split 1460 will also likely make your kernel incompatible with binary-only 1461 kernel modules. 1462 1463 If you are not absolutely sure what you are doing, leave this 1464 option alone! 1465 1466 config VMSPLIT_3G 1467 bool "3G/1G user/kernel split" 1468 config VMSPLIT_3G_OPT 1469 depends on !X86_PAE 1470 bool "3G/1G user/kernel split (for full 1G low memory)" 1471 config VMSPLIT_2G 1472 bool "2G/2G user/kernel split" 1473 config VMSPLIT_2G_OPT 1474 depends on !X86_PAE 1475 bool "2G/2G user/kernel split (for full 2G low memory)" 1476 config VMSPLIT_1G 1477 bool "1G/3G user/kernel split" 1478endchoice 1479 1480config PAGE_OFFSET 1481 hex 1482 default 0xB0000000 if VMSPLIT_3G_OPT 1483 default 0x80000000 if VMSPLIT_2G 1484 default 0x78000000 if VMSPLIT_2G_OPT 1485 default 0x40000000 if VMSPLIT_1G 1486 default 0xC0000000 1487 depends on X86_32 1488 1489config HIGHMEM 1490 def_bool y 1491 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1492 1493config X86_PAE 1494 bool "PAE (Physical Address Extension) Support" 1495 depends on X86_32 && !HIGHMEM4G 1496 select PHYS_ADDR_T_64BIT 1497 select SWIOTLB 1498 help 1499 PAE is required for NX support, and furthermore enables 1500 larger swapspace support for non-overcommit purposes. It 1501 has the cost of more pagetable lookup overhead, and also 1502 consumes more pagetable space per process. 1503 1504config X86_5LEVEL 1505 bool "Enable 5-level page tables support" 1506 default y 1507 select DYNAMIC_MEMORY_LAYOUT 1508 select SPARSEMEM_VMEMMAP 1509 depends on X86_64 1510 help 1511 5-level paging enables access to larger address space: 1512 upto 128 PiB of virtual address space and 4 PiB of 1513 physical address space. 1514 1515 It will be supported by future Intel CPUs. 1516 1517 A kernel with the option enabled can be booted on machines that 1518 support 4- or 5-level paging. 1519 1520 See Documentation/x86/x86_64/5level-paging.rst for more 1521 information. 1522 1523 Say N if unsure. 1524 1525config X86_DIRECT_GBPAGES 1526 def_bool y 1527 depends on X86_64 1528 help 1529 Certain kernel features effectively disable kernel 1530 linear 1 GB mappings (even if the CPU otherwise 1531 supports them), so don't confuse the user by printing 1532 that we have them enabled. 1533 1534config X86_CPA_STATISTICS 1535 bool "Enable statistic for Change Page Attribute" 1536 depends on DEBUG_FS 1537 help 1538 Expose statistics about the Change Page Attribute mechanism, which 1539 helps to determine the effectiveness of preserving large and huge 1540 page mappings when mapping protections are changed. 1541 1542config X86_MEM_ENCRYPT 1543 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1544 select DYNAMIC_PHYSICAL_MASK 1545 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS 1546 def_bool n 1547 1548config AMD_MEM_ENCRYPT 1549 bool "AMD Secure Memory Encryption (SME) support" 1550 depends on X86_64 && CPU_SUP_AMD 1551 select DMA_COHERENT_POOL 1552 select ARCH_USE_MEMREMAP_PROT 1553 select INSTRUCTION_DECODER 1554 select ARCH_HAS_CC_PLATFORM 1555 select X86_MEM_ENCRYPT 1556 help 1557 Say yes to enable support for the encryption of system memory. 1558 This requires an AMD processor that supports Secure Memory 1559 Encryption (SME). 1560 1561config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1562 bool "Activate AMD Secure Memory Encryption (SME) by default" 1563 depends on AMD_MEM_ENCRYPT 1564 help 1565 Say yes to have system memory encrypted by default if running on 1566 an AMD processor that supports Secure Memory Encryption (SME). 1567 1568 If set to Y, then the encryption of system memory can be 1569 deactivated with the mem_encrypt=off command line option. 1570 1571 If set to N, then the encryption of system memory can be 1572 activated with the mem_encrypt=on command line option. 1573 1574# Common NUMA Features 1575config NUMA 1576 bool "NUMA Memory Allocation and Scheduler Support" 1577 depends on SMP 1578 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1579 default y if X86_BIGSMP 1580 select USE_PERCPU_NUMA_NODE_ID 1581 help 1582 Enable NUMA (Non-Uniform Memory Access) support. 1583 1584 The kernel will try to allocate memory used by a CPU on the 1585 local memory controller of the CPU and add some more 1586 NUMA awareness to the kernel. 1587 1588 For 64-bit this is recommended if the system is Intel Core i7 1589 (or later), AMD Opteron, or EM64T NUMA. 1590 1591 For 32-bit this is only needed if you boot a 32-bit 1592 kernel on a 64-bit NUMA platform. 1593 1594 Otherwise, you should say N. 1595 1596config AMD_NUMA 1597 def_bool y 1598 prompt "Old style AMD Opteron NUMA detection" 1599 depends on X86_64 && NUMA && PCI 1600 help 1601 Enable AMD NUMA node topology detection. You should say Y here if 1602 you have a multi processor AMD system. This uses an old method to 1603 read the NUMA configuration directly from the builtin Northbridge 1604 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1605 which also takes priority if both are compiled in. 1606 1607config X86_64_ACPI_NUMA 1608 def_bool y 1609 prompt "ACPI NUMA detection" 1610 depends on X86_64 && NUMA && ACPI && PCI 1611 select ACPI_NUMA 1612 help 1613 Enable ACPI SRAT based node topology detection. 1614 1615config NUMA_EMU 1616 bool "NUMA emulation" 1617 depends on NUMA 1618 help 1619 Enable NUMA emulation. A flat machine will be split 1620 into virtual nodes when booted with "numa=fake=N", where N is the 1621 number of nodes. This is only useful for debugging. 1622 1623config NODES_SHIFT 1624 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1625 range 1 10 1626 default "10" if MAXSMP 1627 default "6" if X86_64 1628 default "3" 1629 depends on NUMA 1630 help 1631 Specify the maximum number of NUMA Nodes available on the target 1632 system. Increases memory reserved to accommodate various tables. 1633 1634config ARCH_FLATMEM_ENABLE 1635 def_bool y 1636 depends on X86_32 && !NUMA 1637 1638config ARCH_SPARSEMEM_ENABLE 1639 def_bool y 1640 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1641 select SPARSEMEM_STATIC if X86_32 1642 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1643 1644config ARCH_SPARSEMEM_DEFAULT 1645 def_bool X86_64 || (NUMA && X86_32) 1646 1647config ARCH_SELECT_MEMORY_MODEL 1648 def_bool y 1649 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1650 1651config ARCH_MEMORY_PROBE 1652 bool "Enable sysfs memory/probe interface" 1653 depends on MEMORY_HOTPLUG 1654 help 1655 This option enables a sysfs memory/probe interface for testing. 1656 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1657 If you are unsure how to answer this question, answer N. 1658 1659config ARCH_PROC_KCORE_TEXT 1660 def_bool y 1661 depends on X86_64 && PROC_KCORE 1662 1663config ILLEGAL_POINTER_VALUE 1664 hex 1665 default 0 if X86_32 1666 default 0xdead000000000000 if X86_64 1667 1668config X86_PMEM_LEGACY_DEVICE 1669 bool 1670 1671config X86_PMEM_LEGACY 1672 tristate "Support non-standard NVDIMMs and ADR protected memory" 1673 depends on PHYS_ADDR_T_64BIT 1674 depends on BLK_DEV 1675 select X86_PMEM_LEGACY_DEVICE 1676 select NUMA_KEEP_MEMINFO if NUMA 1677 select LIBNVDIMM 1678 help 1679 Treat memory marked using the non-standard e820 type of 12 as used 1680 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1681 The kernel will offer these regions to the 'pmem' driver so 1682 they can be used for persistent storage. 1683 1684 Say Y if unsure. 1685 1686config HIGHPTE 1687 bool "Allocate 3rd-level pagetables from highmem" 1688 depends on HIGHMEM 1689 help 1690 The VM uses one page table entry for each page of physical memory. 1691 For systems with a lot of RAM, this can be wasteful of precious 1692 low memory. Setting this option will put user-space page table 1693 entries in high memory. 1694 1695config X86_CHECK_BIOS_CORRUPTION 1696 bool "Check for low memory corruption" 1697 help 1698 Periodically check for memory corruption in low memory, which 1699 is suspected to be caused by BIOS. Even when enabled in the 1700 configuration, it is disabled at runtime. Enable it by 1701 setting "memory_corruption_check=1" on the kernel command 1702 line. By default it scans the low 64k of memory every 60 1703 seconds; see the memory_corruption_check_size and 1704 memory_corruption_check_period parameters in 1705 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1706 1707 When enabled with the default parameters, this option has 1708 almost no overhead, as it reserves a relatively small amount 1709 of memory and scans it infrequently. It both detects corruption 1710 and prevents it from affecting the running system. 1711 1712 It is, however, intended as a diagnostic tool; if repeatable 1713 BIOS-originated corruption always affects the same memory, 1714 you can use memmap= to prevent the kernel from using that 1715 memory. 1716 1717config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1718 bool "Set the default setting of memory_corruption_check" 1719 depends on X86_CHECK_BIOS_CORRUPTION 1720 default y 1721 help 1722 Set whether the default state of memory_corruption_check is 1723 on or off. 1724 1725config MATH_EMULATION 1726 bool 1727 depends on MODIFY_LDT_SYSCALL 1728 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1729 help 1730 Linux can emulate a math coprocessor (used for floating point 1731 operations) if you don't have one. 486DX and Pentium processors have 1732 a math coprocessor built in, 486SX and 386 do not, unless you added 1733 a 487DX or 387, respectively. (The messages during boot time can 1734 give you some hints here ["man dmesg"].) Everyone needs either a 1735 coprocessor or this emulation. 1736 1737 If you don't have a math coprocessor, you need to say Y here; if you 1738 say Y here even though you have a coprocessor, the coprocessor will 1739 be used nevertheless. (This behavior can be changed with the kernel 1740 command line option "no387", which comes handy if your coprocessor 1741 is broken. Try "man bootparam" or see the documentation of your boot 1742 loader (lilo or loadlin) about how to pass options to the kernel at 1743 boot time.) This means that it is a good idea to say Y here if you 1744 intend to use this kernel on different machines. 1745 1746 More information about the internals of the Linux math coprocessor 1747 emulation can be found in <file:arch/x86/math-emu/README>. 1748 1749 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1750 kernel, it won't hurt. 1751 1752config MTRR 1753 def_bool y 1754 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1755 help 1756 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1757 the Memory Type Range Registers (MTRRs) may be used to control 1758 processor access to memory ranges. This is most useful if you have 1759 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1760 allows bus write transfers to be combined into a larger transfer 1761 before bursting over the PCI/AGP bus. This can increase performance 1762 of image write operations 2.5 times or more. Saying Y here creates a 1763 /proc/mtrr file which may be used to manipulate your processor's 1764 MTRRs. Typically the X server should use this. 1765 1766 This code has a reasonably generic interface so that similar 1767 control registers on other processors can be easily supported 1768 as well: 1769 1770 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1771 Registers (ARRs) which provide a similar functionality to MTRRs. For 1772 these, the ARRs are used to emulate the MTRRs. 1773 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1774 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1775 write-combining. All of these processors are supported by this code 1776 and it makes sense to say Y here if you have one of them. 1777 1778 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1779 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1780 can lead to all sorts of problems, so it's good to say Y here. 1781 1782 You can safely say Y even if your machine doesn't have MTRRs, you'll 1783 just add about 9 KB to your kernel. 1784 1785 See <file:Documentation/x86/mtrr.rst> for more information. 1786 1787config MTRR_SANITIZER 1788 def_bool y 1789 prompt "MTRR cleanup support" 1790 depends on MTRR 1791 help 1792 Convert MTRR layout from continuous to discrete, so X drivers can 1793 add writeback entries. 1794 1795 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1796 The largest mtrr entry size for a continuous block can be set with 1797 mtrr_chunk_size. 1798 1799 If unsure, say Y. 1800 1801config MTRR_SANITIZER_ENABLE_DEFAULT 1802 int "MTRR cleanup enable value (0-1)" 1803 range 0 1 1804 default "0" 1805 depends on MTRR_SANITIZER 1806 help 1807 Enable mtrr cleanup default value 1808 1809config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1810 int "MTRR cleanup spare reg num (0-7)" 1811 range 0 7 1812 default "1" 1813 depends on MTRR_SANITIZER 1814 help 1815 mtrr cleanup spare entries default, it can be changed via 1816 mtrr_spare_reg_nr=N on the kernel command line. 1817 1818config X86_PAT 1819 def_bool y 1820 prompt "x86 PAT support" if EXPERT 1821 depends on MTRR 1822 help 1823 Use PAT attributes to setup page level cache control. 1824 1825 PATs are the modern equivalents of MTRRs and are much more 1826 flexible than MTRRs. 1827 1828 Say N here if you see bootup problems (boot crash, boot hang, 1829 spontaneous reboots) or a non-working video driver. 1830 1831 If unsure, say Y. 1832 1833config ARCH_USES_PG_UNCACHED 1834 def_bool y 1835 depends on X86_PAT 1836 1837config ARCH_RANDOM 1838 def_bool y 1839 prompt "x86 architectural random number generator" if EXPERT 1840 help 1841 Enable the x86 architectural RDRAND instruction 1842 (Intel Bull Mountain technology) to generate random numbers. 1843 If supported, this is a high bandwidth, cryptographically 1844 secure hardware random number generator. 1845 1846config X86_UMIP 1847 def_bool y 1848 prompt "User Mode Instruction Prevention" if EXPERT 1849 help 1850 User Mode Instruction Prevention (UMIP) is a security feature in 1851 some x86 processors. If enabled, a general protection fault is 1852 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1853 executed in user mode. These instructions unnecessarily expose 1854 information about the hardware state. 1855 1856 The vast majority of applications do not use these instructions. 1857 For the very few that do, software emulation is provided in 1858 specific cases in protected and virtual-8086 modes. Emulated 1859 results are dummy. 1860 1861config CC_HAS_IBT 1862 # GCC >= 9 and binutils >= 2.29 1863 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1864 # Clang/LLVM >= 14 1865 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1866 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1867 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1868 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1869 $(as-instr,endbr64) 1870 1871config X86_KERNEL_IBT 1872 prompt "Indirect Branch Tracking" 1873 bool 1874 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1875 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1876 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1877 select OBJTOOL 1878 help 1879 Build the kernel with support for Indirect Branch Tracking, a 1880 hardware support course-grain forward-edge Control Flow Integrity 1881 protection. It enforces that all indirect calls must land on 1882 an ENDBR instruction, as such, the compiler will instrument the 1883 code with them to make this happen. 1884 1885 In addition to building the kernel with IBT, seal all functions that 1886 are not indirect call targets, avoiding them ever becoming one. 1887 1888 This requires LTO like objtool runs and will slow down the build. It 1889 does significantly reduce the number of ENDBR instructions in the 1890 kernel image. 1891 1892config X86_INTEL_MEMORY_PROTECTION_KEYS 1893 prompt "Memory Protection Keys" 1894 def_bool y 1895 # Note: only available in 64-bit mode 1896 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1897 select ARCH_USES_HIGH_VMA_FLAGS 1898 select ARCH_HAS_PKEYS 1899 help 1900 Memory Protection Keys provides a mechanism for enforcing 1901 page-based protections, but without requiring modification of the 1902 page tables when an application changes protection domains. 1903 1904 For details, see Documentation/core-api/protection-keys.rst 1905 1906 If unsure, say y. 1907 1908choice 1909 prompt "TSX enable mode" 1910 depends on CPU_SUP_INTEL 1911 default X86_INTEL_TSX_MODE_OFF 1912 help 1913 Intel's TSX (Transactional Synchronization Extensions) feature 1914 allows to optimize locking protocols through lock elision which 1915 can lead to a noticeable performance boost. 1916 1917 On the other hand it has been shown that TSX can be exploited 1918 to form side channel attacks (e.g. TAA) and chances are there 1919 will be more of those attacks discovered in the future. 1920 1921 Therefore TSX is not enabled by default (aka tsx=off). An admin 1922 might override this decision by tsx=on the command line parameter. 1923 Even with TSX enabled, the kernel will attempt to enable the best 1924 possible TAA mitigation setting depending on the microcode available 1925 for the particular machine. 1926 1927 This option allows to set the default tsx mode between tsx=on, =off 1928 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1929 details. 1930 1931 Say off if not sure, auto if TSX is in use but it should be used on safe 1932 platforms or on if TSX is in use and the security aspect of tsx is not 1933 relevant. 1934 1935config X86_INTEL_TSX_MODE_OFF 1936 bool "off" 1937 help 1938 TSX is disabled if possible - equals to tsx=off command line parameter. 1939 1940config X86_INTEL_TSX_MODE_ON 1941 bool "on" 1942 help 1943 TSX is always enabled on TSX capable HW - equals the tsx=on command 1944 line parameter. 1945 1946config X86_INTEL_TSX_MODE_AUTO 1947 bool "auto" 1948 help 1949 TSX is enabled on TSX capable HW that is believed to be safe against 1950 side channel attacks- equals the tsx=auto command line parameter. 1951endchoice 1952 1953config X86_SGX 1954 bool "Software Guard eXtensions (SGX)" 1955 depends on X86_64 && CPU_SUP_INTEL 1956 depends on CRYPTO=y 1957 depends on CRYPTO_SHA256=y 1958 select SRCU 1959 select MMU_NOTIFIER 1960 select NUMA_KEEP_MEMINFO if NUMA 1961 select XARRAY_MULTI 1962 help 1963 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1964 that can be used by applications to set aside private regions of code 1965 and data, referred to as enclaves. An enclave's private memory can 1966 only be accessed by code running within the enclave. Accesses from 1967 outside the enclave, including other enclaves, are disallowed by 1968 hardware. 1969 1970 If unsure, say N. 1971 1972config EFI 1973 bool "EFI runtime service support" 1974 depends on ACPI 1975 select UCS2_STRING 1976 select EFI_RUNTIME_WRAPPERS 1977 select ARCH_USE_MEMREMAP_PROT 1978 help 1979 This enables the kernel to use EFI runtime services that are 1980 available (such as the EFI variable services). 1981 1982 This option is only useful on systems that have EFI firmware. 1983 In addition, you should use the latest ELILO loader available 1984 at <http://elilo.sourceforge.net> in order to take advantage 1985 of EFI runtime services. However, even with this option, the 1986 resultant kernel should continue to boot on existing non-EFI 1987 platforms. 1988 1989config EFI_STUB 1990 bool "EFI stub support" 1991 depends on EFI 1992 depends on $(cc-option,-mabi=ms) || X86_32 1993 select RELOCATABLE 1994 help 1995 This kernel feature allows a bzImage to be loaded directly 1996 by EFI firmware without the use of a bootloader. 1997 1998 See Documentation/admin-guide/efi-stub.rst for more information. 1999 2000config EFI_MIXED 2001 bool "EFI mixed-mode support" 2002 depends on EFI_STUB && X86_64 2003 help 2004 Enabling this feature allows a 64-bit kernel to be booted 2005 on a 32-bit firmware, provided that your CPU supports 64-bit 2006 mode. 2007 2008 Note that it is not possible to boot a mixed-mode enabled 2009 kernel via the EFI boot stub - a bootloader that supports 2010 the EFI handover protocol must be used. 2011 2012 If unsure, say N. 2013 2014source "kernel/Kconfig.hz" 2015 2016config KEXEC 2017 bool "kexec system call" 2018 select KEXEC_CORE 2019 help 2020 kexec is a system call that implements the ability to shutdown your 2021 current kernel, and to start another kernel. It is like a reboot 2022 but it is independent of the system firmware. And like a reboot 2023 you can start any kernel with it, not just Linux. 2024 2025 The name comes from the similarity to the exec system call. 2026 2027 It is an ongoing process to be certain the hardware in a machine 2028 is properly shutdown, so do not be surprised if this code does not 2029 initially work for you. As of this writing the exact hardware 2030 interface is strongly in flux, so no good recommendation can be 2031 made. 2032 2033config KEXEC_FILE 2034 bool "kexec file based system call" 2035 select KEXEC_CORE 2036 select BUILD_BIN2C 2037 depends on X86_64 2038 depends on CRYPTO=y 2039 depends on CRYPTO_SHA256=y 2040 help 2041 This is new version of kexec system call. This system call is 2042 file based and takes file descriptors as system call argument 2043 for kernel and initramfs as opposed to list of segments as 2044 accepted by previous system call. 2045 2046config ARCH_HAS_KEXEC_PURGATORY 2047 def_bool KEXEC_FILE 2048 2049config KEXEC_SIG 2050 bool "Verify kernel signature during kexec_file_load() syscall" 2051 depends on KEXEC_FILE 2052 help 2053 2054 This option makes the kexec_file_load() syscall check for a valid 2055 signature of the kernel image. The image can still be loaded without 2056 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2057 there's a signature that we can check, then it must be valid. 2058 2059 In addition to this option, you need to enable signature 2060 verification for the corresponding kernel image type being 2061 loaded in order for this to work. 2062 2063config KEXEC_SIG_FORCE 2064 bool "Require a valid signature in kexec_file_load() syscall" 2065 depends on KEXEC_SIG 2066 help 2067 This option makes kernel signature verification mandatory for 2068 the kexec_file_load() syscall. 2069 2070config KEXEC_BZIMAGE_VERIFY_SIG 2071 bool "Enable bzImage signature verification support" 2072 depends on KEXEC_SIG 2073 depends on SIGNED_PE_FILE_VERIFICATION 2074 select SYSTEM_TRUSTED_KEYRING 2075 help 2076 Enable bzImage signature verification support. 2077 2078config CRASH_DUMP 2079 bool "kernel crash dumps" 2080 depends on X86_64 || (X86_32 && HIGHMEM) 2081 help 2082 Generate crash dump after being started by kexec. 2083 This should be normally only set in special crash dump kernels 2084 which are loaded in the main kernel with kexec-tools into 2085 a specially reserved region and then later executed after 2086 a crash by kdump/kexec. The crash dump kernel must be compiled 2087 to a memory address not used by the main kernel or BIOS using 2088 PHYSICAL_START, or it must be built as a relocatable image 2089 (CONFIG_RELOCATABLE=y). 2090 For more details see Documentation/admin-guide/kdump/kdump.rst 2091 2092config KEXEC_JUMP 2093 bool "kexec jump" 2094 depends on KEXEC && HIBERNATION 2095 help 2096 Jump between original kernel and kexeced kernel and invoke 2097 code in physical address mode via KEXEC 2098 2099config PHYSICAL_START 2100 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2101 default "0x1000000" 2102 help 2103 This gives the physical address where the kernel is loaded. 2104 2105 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2106 bzImage will decompress itself to above physical address and 2107 run from there. Otherwise, bzImage will run from the address where 2108 it has been loaded by the boot loader and will ignore above physical 2109 address. 2110 2111 In normal kdump cases one does not have to set/change this option 2112 as now bzImage can be compiled as a completely relocatable image 2113 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2114 address. This option is mainly useful for the folks who don't want 2115 to use a bzImage for capturing the crash dump and want to use a 2116 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2117 to be specifically compiled to run from a specific memory area 2118 (normally a reserved region) and this option comes handy. 2119 2120 So if you are using bzImage for capturing the crash dump, 2121 leave the value here unchanged to 0x1000000 and set 2122 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2123 for capturing the crash dump change this value to start of 2124 the reserved region. In other words, it can be set based on 2125 the "X" value as specified in the "crashkernel=YM@XM" 2126 command line boot parameter passed to the panic-ed 2127 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2128 for more details about crash dumps. 2129 2130 Usage of bzImage for capturing the crash dump is recommended as 2131 one does not have to build two kernels. Same kernel can be used 2132 as production kernel and capture kernel. Above option should have 2133 gone away after relocatable bzImage support is introduced. But it 2134 is present because there are users out there who continue to use 2135 vmlinux for dump capture. This option should go away down the 2136 line. 2137 2138 Don't change this unless you know what you are doing. 2139 2140config RELOCATABLE 2141 bool "Build a relocatable kernel" 2142 default y 2143 help 2144 This builds a kernel image that retains relocation information 2145 so it can be loaded someplace besides the default 1MB. 2146 The relocations tend to make the kernel binary about 10% larger, 2147 but are discarded at runtime. 2148 2149 One use is for the kexec on panic case where the recovery kernel 2150 must live at a different physical address than the primary 2151 kernel. 2152 2153 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2154 it has been loaded at and the compile time physical address 2155 (CONFIG_PHYSICAL_START) is used as the minimum location. 2156 2157config RANDOMIZE_BASE 2158 bool "Randomize the address of the kernel image (KASLR)" 2159 depends on RELOCATABLE 2160 default y 2161 help 2162 In support of Kernel Address Space Layout Randomization (KASLR), 2163 this randomizes the physical address at which the kernel image 2164 is decompressed and the virtual address where the kernel 2165 image is mapped, as a security feature that deters exploit 2166 attempts relying on knowledge of the location of kernel 2167 code internals. 2168 2169 On 64-bit, the kernel physical and virtual addresses are 2170 randomized separately. The physical address will be anywhere 2171 between 16MB and the top of physical memory (up to 64TB). The 2172 virtual address will be randomized from 16MB up to 1GB (9 bits 2173 of entropy). Note that this also reduces the memory space 2174 available to kernel modules from 1.5GB to 1GB. 2175 2176 On 32-bit, the kernel physical and virtual addresses are 2177 randomized together. They will be randomized from 16MB up to 2178 512MB (8 bits of entropy). 2179 2180 Entropy is generated using the RDRAND instruction if it is 2181 supported. If RDTSC is supported, its value is mixed into 2182 the entropy pool as well. If neither RDRAND nor RDTSC are 2183 supported, then entropy is read from the i8254 timer. The 2184 usable entropy is limited by the kernel being built using 2185 2GB addressing, and that PHYSICAL_ALIGN must be at a 2186 minimum of 2MB. As a result, only 10 bits of entropy are 2187 theoretically possible, but the implementations are further 2188 limited due to memory layouts. 2189 2190 If unsure, say Y. 2191 2192# Relocation on x86 needs some additional build support 2193config X86_NEED_RELOCS 2194 def_bool y 2195 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2196 2197config PHYSICAL_ALIGN 2198 hex "Alignment value to which kernel should be aligned" 2199 default "0x200000" 2200 range 0x2000 0x1000000 if X86_32 2201 range 0x200000 0x1000000 if X86_64 2202 help 2203 This value puts the alignment restrictions on physical address 2204 where kernel is loaded and run from. Kernel is compiled for an 2205 address which meets above alignment restriction. 2206 2207 If bootloader loads the kernel at a non-aligned address and 2208 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2209 address aligned to above value and run from there. 2210 2211 If bootloader loads the kernel at a non-aligned address and 2212 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2213 load address and decompress itself to the address it has been 2214 compiled for and run from there. The address for which kernel is 2215 compiled already meets above alignment restrictions. Hence the 2216 end result is that kernel runs from a physical address meeting 2217 above alignment restrictions. 2218 2219 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2220 this value must be a multiple of 0x200000. 2221 2222 Don't change this unless you know what you are doing. 2223 2224config DYNAMIC_MEMORY_LAYOUT 2225 bool 2226 help 2227 This option makes base addresses of vmalloc and vmemmap as well as 2228 __PAGE_OFFSET movable during boot. 2229 2230config RANDOMIZE_MEMORY 2231 bool "Randomize the kernel memory sections" 2232 depends on X86_64 2233 depends on RANDOMIZE_BASE 2234 select DYNAMIC_MEMORY_LAYOUT 2235 default RANDOMIZE_BASE 2236 help 2237 Randomizes the base virtual address of kernel memory sections 2238 (physical memory mapping, vmalloc & vmemmap). This security feature 2239 makes exploits relying on predictable memory locations less reliable. 2240 2241 The order of allocations remains unchanged. Entropy is generated in 2242 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2243 configuration have in average 30,000 different possible virtual 2244 addresses for each memory section. 2245 2246 If unsure, say Y. 2247 2248config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2249 hex "Physical memory mapping padding" if EXPERT 2250 depends on RANDOMIZE_MEMORY 2251 default "0xa" if MEMORY_HOTPLUG 2252 default "0x0" 2253 range 0x1 0x40 if MEMORY_HOTPLUG 2254 range 0x0 0x40 2255 help 2256 Define the padding in terabytes added to the existing physical 2257 memory size during kernel memory randomization. It is useful 2258 for memory hotplug support but reduces the entropy available for 2259 address randomization. 2260 2261 If unsure, leave at the default value. 2262 2263config HOTPLUG_CPU 2264 def_bool y 2265 depends on SMP 2266 2267config BOOTPARAM_HOTPLUG_CPU0 2268 bool "Set default setting of cpu0_hotpluggable" 2269 depends on HOTPLUG_CPU 2270 help 2271 Set whether default state of cpu0_hotpluggable is on or off. 2272 2273 Say Y here to enable CPU0 hotplug by default. If this switch 2274 is turned on, there is no need to give cpu0_hotplug kernel 2275 parameter and the CPU0 hotplug feature is enabled by default. 2276 2277 Please note: there are two known CPU0 dependencies if you want 2278 to enable the CPU0 hotplug feature either by this switch or by 2279 cpu0_hotplug kernel parameter. 2280 2281 First, resume from hibernate or suspend always starts from CPU0. 2282 So hibernate and suspend are prevented if CPU0 is offline. 2283 2284 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2285 offline if any interrupt can not migrate out of CPU0. There may 2286 be other CPU0 dependencies. 2287 2288 Please make sure the dependencies are under your control before 2289 you enable this feature. 2290 2291 Say N if you don't want to enable CPU0 hotplug feature by default. 2292 You still can enable the CPU0 hotplug feature at boot by kernel 2293 parameter cpu0_hotplug. 2294 2295config DEBUG_HOTPLUG_CPU0 2296 def_bool n 2297 prompt "Debug CPU0 hotplug" 2298 depends on HOTPLUG_CPU 2299 help 2300 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2301 soon as possible and boots up userspace with CPU0 offlined. User 2302 can online CPU0 back after boot time. 2303 2304 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2305 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2306 compilation or giving cpu0_hotplug kernel parameter at boot. 2307 2308 If unsure, say N. 2309 2310config COMPAT_VDSO 2311 def_bool n 2312 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2313 depends on COMPAT_32 2314 help 2315 Certain buggy versions of glibc will crash if they are 2316 presented with a 32-bit vDSO that is not mapped at the address 2317 indicated in its segment table. 2318 2319 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2320 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2321 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2322 the only released version with the bug, but OpenSUSE 9 2323 contains a buggy "glibc 2.3.2". 2324 2325 The symptom of the bug is that everything crashes on startup, saying: 2326 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2327 2328 Saying Y here changes the default value of the vdso32 boot 2329 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2330 This works around the glibc bug but hurts performance. 2331 2332 If unsure, say N: if you are compiling your own kernel, you 2333 are unlikely to be using a buggy version of glibc. 2334 2335choice 2336 prompt "vsyscall table for legacy applications" 2337 depends on X86_64 2338 default LEGACY_VSYSCALL_XONLY 2339 help 2340 Legacy user code that does not know how to find the vDSO expects 2341 to be able to issue three syscalls by calling fixed addresses in 2342 kernel space. Since this location is not randomized with ASLR, 2343 it can be used to assist security vulnerability exploitation. 2344 2345 This setting can be changed at boot time via the kernel command 2346 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2347 is deprecated and can only be enabled using the kernel command 2348 line. 2349 2350 On a system with recent enough glibc (2.14 or newer) and no 2351 static binaries, you can say None without a performance penalty 2352 to improve security. 2353 2354 If unsure, select "Emulate execution only". 2355 2356 config LEGACY_VSYSCALL_XONLY 2357 bool "Emulate execution only" 2358 help 2359 The kernel traps and emulates calls into the fixed vsyscall 2360 address mapping and does not allow reads. This 2361 configuration is recommended when userspace might use the 2362 legacy vsyscall area but support for legacy binary 2363 instrumentation of legacy code is not needed. It mitigates 2364 certain uses of the vsyscall area as an ASLR-bypassing 2365 buffer. 2366 2367 config LEGACY_VSYSCALL_NONE 2368 bool "None" 2369 help 2370 There will be no vsyscall mapping at all. This will 2371 eliminate any risk of ASLR bypass due to the vsyscall 2372 fixed address mapping. Attempts to use the vsyscalls 2373 will be reported to dmesg, so that either old or 2374 malicious userspace programs can be identified. 2375 2376endchoice 2377 2378config CMDLINE_BOOL 2379 bool "Built-in kernel command line" 2380 help 2381 Allow for specifying boot arguments to the kernel at 2382 build time. On some systems (e.g. embedded ones), it is 2383 necessary or convenient to provide some or all of the 2384 kernel boot arguments with the kernel itself (that is, 2385 to not rely on the boot loader to provide them.) 2386 2387 To compile command line arguments into the kernel, 2388 set this option to 'Y', then fill in the 2389 boot arguments in CONFIG_CMDLINE. 2390 2391 Systems with fully functional boot loaders (i.e. non-embedded) 2392 should leave this option set to 'N'. 2393 2394config CMDLINE 2395 string "Built-in kernel command string" 2396 depends on CMDLINE_BOOL 2397 default "" 2398 help 2399 Enter arguments here that should be compiled into the kernel 2400 image and used at boot time. If the boot loader provides a 2401 command line at boot time, it is appended to this string to 2402 form the full kernel command line, when the system boots. 2403 2404 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2405 change this behavior. 2406 2407 In most cases, the command line (whether built-in or provided 2408 by the boot loader) should specify the device for the root 2409 file system. 2410 2411config CMDLINE_OVERRIDE 2412 bool "Built-in command line overrides boot loader arguments" 2413 depends on CMDLINE_BOOL && CMDLINE != "" 2414 help 2415 Set this option to 'Y' to have the kernel ignore the boot loader 2416 command line, and use ONLY the built-in command line. 2417 2418 This is used to work around broken boot loaders. This should 2419 be set to 'N' under normal conditions. 2420 2421config MODIFY_LDT_SYSCALL 2422 bool "Enable the LDT (local descriptor table)" if EXPERT 2423 default y 2424 help 2425 Linux can allow user programs to install a per-process x86 2426 Local Descriptor Table (LDT) using the modify_ldt(2) system 2427 call. This is required to run 16-bit or segmented code such as 2428 DOSEMU or some Wine programs. It is also used by some very old 2429 threading libraries. 2430 2431 Enabling this feature adds a small amount of overhead to 2432 context switches and increases the low-level kernel attack 2433 surface. Disabling it removes the modify_ldt(2) system call. 2434 2435 Saying 'N' here may make sense for embedded or server kernels. 2436 2437config STRICT_SIGALTSTACK_SIZE 2438 bool "Enforce strict size checking for sigaltstack" 2439 depends on DYNAMIC_SIGFRAME 2440 help 2441 For historical reasons MINSIGSTKSZ is a constant which became 2442 already too small with AVX512 support. Add a mechanism to 2443 enforce strict checking of the sigaltstack size against the 2444 real size of the FPU frame. This option enables the check 2445 by default. It can also be controlled via the kernel command 2446 line option 'strict_sas_size' independent of this config 2447 switch. Enabling it might break existing applications which 2448 allocate a too small sigaltstack but 'work' because they 2449 never get a signal delivered. 2450 2451 Say 'N' unless you want to really enforce this check. 2452 2453source "kernel/livepatch/Kconfig" 2454 2455endmenu 2456 2457config ARCH_HAS_ADD_PAGES 2458 def_bool y 2459 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2460 2461config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2462 def_bool y 2463 2464menu "Power management and ACPI options" 2465 2466config ARCH_HIBERNATION_HEADER 2467 def_bool y 2468 depends on HIBERNATION 2469 2470source "kernel/power/Kconfig" 2471 2472source "drivers/acpi/Kconfig" 2473 2474config X86_APM_BOOT 2475 def_bool y 2476 depends on APM 2477 2478menuconfig APM 2479 tristate "APM (Advanced Power Management) BIOS support" 2480 depends on X86_32 && PM_SLEEP 2481 help 2482 APM is a BIOS specification for saving power using several different 2483 techniques. This is mostly useful for battery powered laptops with 2484 APM compliant BIOSes. If you say Y here, the system time will be 2485 reset after a RESUME operation, the /proc/apm device will provide 2486 battery status information, and user-space programs will receive 2487 notification of APM "events" (e.g. battery status change). 2488 2489 If you select "Y" here, you can disable actual use of the APM 2490 BIOS by passing the "apm=off" option to the kernel at boot time. 2491 2492 Note that the APM support is almost completely disabled for 2493 machines with more than one CPU. 2494 2495 In order to use APM, you will need supporting software. For location 2496 and more information, read <file:Documentation/power/apm-acpi.rst> 2497 and the Battery Powered Linux mini-HOWTO, available from 2498 <http://www.tldp.org/docs.html#howto>. 2499 2500 This driver does not spin down disk drives (see the hdparm(8) 2501 manpage ("man 8 hdparm") for that), and it doesn't turn off 2502 VESA-compliant "green" monitors. 2503 2504 This driver does not support the TI 4000M TravelMate and the ACER 2505 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2506 desktop machines also don't have compliant BIOSes, and this driver 2507 may cause those machines to panic during the boot phase. 2508 2509 Generally, if you don't have a battery in your machine, there isn't 2510 much point in using this driver and you should say N. If you get 2511 random kernel OOPSes or reboots that don't seem to be related to 2512 anything, try disabling/enabling this option (or disabling/enabling 2513 APM in your BIOS). 2514 2515 Some other things you should try when experiencing seemingly random, 2516 "weird" problems: 2517 2518 1) make sure that you have enough swap space and that it is 2519 enabled. 2520 2) pass the "no-hlt" option to the kernel 2521 3) switch on floating point emulation in the kernel and pass 2522 the "no387" option to the kernel 2523 4) pass the "floppy=nodma" option to the kernel 2524 5) pass the "mem=4M" option to the kernel (thereby disabling 2525 all but the first 4 MB of RAM) 2526 6) make sure that the CPU is not over clocked. 2527 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2528 8) disable the cache from your BIOS settings 2529 9) install a fan for the video card or exchange video RAM 2530 10) install a better fan for the CPU 2531 11) exchange RAM chips 2532 12) exchange the motherboard. 2533 2534 To compile this driver as a module, choose M here: the 2535 module will be called apm. 2536 2537if APM 2538 2539config APM_IGNORE_USER_SUSPEND 2540 bool "Ignore USER SUSPEND" 2541 help 2542 This option will ignore USER SUSPEND requests. On machines with a 2543 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2544 series notebooks, it is necessary to say Y because of a BIOS bug. 2545 2546config APM_DO_ENABLE 2547 bool "Enable PM at boot time" 2548 help 2549 Enable APM features at boot time. From page 36 of the APM BIOS 2550 specification: "When disabled, the APM BIOS does not automatically 2551 power manage devices, enter the Standby State, enter the Suspend 2552 State, or take power saving steps in response to CPU Idle calls." 2553 This driver will make CPU Idle calls when Linux is idle (unless this 2554 feature is turned off -- see "Do CPU IDLE calls", below). This 2555 should always save battery power, but more complicated APM features 2556 will be dependent on your BIOS implementation. You may need to turn 2557 this option off if your computer hangs at boot time when using APM 2558 support, or if it beeps continuously instead of suspending. Turn 2559 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2560 T400CDT. This is off by default since most machines do fine without 2561 this feature. 2562 2563config APM_CPU_IDLE 2564 depends on CPU_IDLE 2565 bool "Make CPU Idle calls when idle" 2566 help 2567 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2568 On some machines, this can activate improved power savings, such as 2569 a slowed CPU clock rate, when the machine is idle. These idle calls 2570 are made after the idle loop has run for some length of time (e.g., 2571 333 mS). On some machines, this will cause a hang at boot time or 2572 whenever the CPU becomes idle. (On machines with more than one CPU, 2573 this option does nothing.) 2574 2575config APM_DISPLAY_BLANK 2576 bool "Enable console blanking using APM" 2577 help 2578 Enable console blanking using the APM. Some laptops can use this to 2579 turn off the LCD backlight when the screen blanker of the Linux 2580 virtual console blanks the screen. Note that this is only used by 2581 the virtual console screen blanker, and won't turn off the backlight 2582 when using the X Window system. This also doesn't have anything to 2583 do with your VESA-compliant power-saving monitor. Further, this 2584 option doesn't work for all laptops -- it might not turn off your 2585 backlight at all, or it might print a lot of errors to the console, 2586 especially if you are using gpm. 2587 2588config APM_ALLOW_INTS 2589 bool "Allow interrupts during APM BIOS calls" 2590 help 2591 Normally we disable external interrupts while we are making calls to 2592 the APM BIOS as a measure to lessen the effects of a badly behaving 2593 BIOS implementation. The BIOS should reenable interrupts if it 2594 needs to. Unfortunately, some BIOSes do not -- especially those in 2595 many of the newer IBM Thinkpads. If you experience hangs when you 2596 suspend, try setting this to Y. Otherwise, say N. 2597 2598endif # APM 2599 2600source "drivers/cpufreq/Kconfig" 2601 2602source "drivers/cpuidle/Kconfig" 2603 2604source "drivers/idle/Kconfig" 2605 2606endmenu 2607 2608menu "Bus options (PCI etc.)" 2609 2610choice 2611 prompt "PCI access mode" 2612 depends on X86_32 && PCI 2613 default PCI_GOANY 2614 help 2615 On PCI systems, the BIOS can be used to detect the PCI devices and 2616 determine their configuration. However, some old PCI motherboards 2617 have BIOS bugs and may crash if this is done. Also, some embedded 2618 PCI-based systems don't have any BIOS at all. Linux can also try to 2619 detect the PCI hardware directly without using the BIOS. 2620 2621 With this option, you can specify how Linux should detect the 2622 PCI devices. If you choose "BIOS", the BIOS will be used, 2623 if you choose "Direct", the BIOS won't be used, and if you 2624 choose "MMConfig", then PCI Express MMCONFIG will be used. 2625 If you choose "Any", the kernel will try MMCONFIG, then the 2626 direct access method and falls back to the BIOS if that doesn't 2627 work. If unsure, go with the default, which is "Any". 2628 2629config PCI_GOBIOS 2630 bool "BIOS" 2631 2632config PCI_GOMMCONFIG 2633 bool "MMConfig" 2634 2635config PCI_GODIRECT 2636 bool "Direct" 2637 2638config PCI_GOOLPC 2639 bool "OLPC XO-1" 2640 depends on OLPC 2641 2642config PCI_GOANY 2643 bool "Any" 2644 2645endchoice 2646 2647config PCI_BIOS 2648 def_bool y 2649 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2650 2651# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2652config PCI_DIRECT 2653 def_bool y 2654 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2655 2656config PCI_MMCONFIG 2657 bool "Support mmconfig PCI config space access" if X86_64 2658 default y 2659 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2660 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2661 2662config PCI_OLPC 2663 def_bool y 2664 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2665 2666config PCI_XEN 2667 def_bool y 2668 depends on PCI && XEN 2669 2670config MMCONF_FAM10H 2671 def_bool y 2672 depends on X86_64 && PCI_MMCONFIG && ACPI 2673 2674config PCI_CNB20LE_QUIRK 2675 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2676 depends on PCI 2677 help 2678 Read the PCI windows out of the CNB20LE host bridge. This allows 2679 PCI hotplug to work on systems with the CNB20LE chipset which do 2680 not have ACPI. 2681 2682 There's no public spec for this chipset, and this functionality 2683 is known to be incomplete. 2684 2685 You should say N unless you know you need this. 2686 2687config ISA_BUS 2688 bool "ISA bus support on modern systems" if EXPERT 2689 help 2690 Expose ISA bus device drivers and options available for selection and 2691 configuration. Enable this option if your target machine has an ISA 2692 bus. ISA is an older system, displaced by PCI and newer bus 2693 architectures -- if your target machine is modern, it probably does 2694 not have an ISA bus. 2695 2696 If unsure, say N. 2697 2698# x86_64 have no ISA slots, but can have ISA-style DMA. 2699config ISA_DMA_API 2700 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2701 default y 2702 help 2703 Enables ISA-style DMA support for devices requiring such controllers. 2704 If unsure, say Y. 2705 2706if X86_32 2707 2708config ISA 2709 bool "ISA support" 2710 help 2711 Find out whether you have ISA slots on your motherboard. ISA is the 2712 name of a bus system, i.e. the way the CPU talks to the other stuff 2713 inside your box. Other bus systems are PCI, EISA, MicroChannel 2714 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2715 newer boards don't support it. If you have ISA, say Y, otherwise N. 2716 2717config SCx200 2718 tristate "NatSemi SCx200 support" 2719 help 2720 This provides basic support for National Semiconductor's 2721 (now AMD's) Geode processors. The driver probes for the 2722 PCI-IDs of several on-chip devices, so its a good dependency 2723 for other scx200_* drivers. 2724 2725 If compiled as a module, the driver is named scx200. 2726 2727config SCx200HR_TIMER 2728 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2729 depends on SCx200 2730 default y 2731 help 2732 This driver provides a clocksource built upon the on-chip 2733 27MHz high-resolution timer. Its also a workaround for 2734 NSC Geode SC-1100's buggy TSC, which loses time when the 2735 processor goes idle (as is done by the scheduler). The 2736 other workaround is idle=poll boot option. 2737 2738config OLPC 2739 bool "One Laptop Per Child support" 2740 depends on !X86_PAE 2741 select GPIOLIB 2742 select OF 2743 select OF_PROMTREE 2744 select IRQ_DOMAIN 2745 select OLPC_EC 2746 help 2747 Add support for detecting the unique features of the OLPC 2748 XO hardware. 2749 2750config OLPC_XO1_PM 2751 bool "OLPC XO-1 Power Management" 2752 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2753 help 2754 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2755 2756config OLPC_XO1_RTC 2757 bool "OLPC XO-1 Real Time Clock" 2758 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2759 help 2760 Add support for the XO-1 real time clock, which can be used as a 2761 programmable wakeup source. 2762 2763config OLPC_XO1_SCI 2764 bool "OLPC XO-1 SCI extras" 2765 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2766 depends on INPUT=y 2767 select POWER_SUPPLY 2768 help 2769 Add support for SCI-based features of the OLPC XO-1 laptop: 2770 - EC-driven system wakeups 2771 - Power button 2772 - Ebook switch 2773 - Lid switch 2774 - AC adapter status updates 2775 - Battery status updates 2776 2777config OLPC_XO15_SCI 2778 bool "OLPC XO-1.5 SCI extras" 2779 depends on OLPC && ACPI 2780 select POWER_SUPPLY 2781 help 2782 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2783 - EC-driven system wakeups 2784 - AC adapter status updates 2785 - Battery status updates 2786 2787config ALIX 2788 bool "PCEngines ALIX System Support (LED setup)" 2789 select GPIOLIB 2790 help 2791 This option enables system support for the PCEngines ALIX. 2792 At present this just sets up LEDs for GPIO control on 2793 ALIX2/3/6 boards. However, other system specific setup should 2794 get added here. 2795 2796 Note: You must still enable the drivers for GPIO and LED support 2797 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2798 2799 Note: You have to set alix.force=1 for boards with Award BIOS. 2800 2801config NET5501 2802 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2803 select GPIOLIB 2804 help 2805 This option enables system support for the Soekris Engineering net5501. 2806 2807config GEOS 2808 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2809 select GPIOLIB 2810 depends on DMI 2811 help 2812 This option enables system support for the Traverse Technologies GEOS. 2813 2814config TS5500 2815 bool "Technologic Systems TS-5500 platform support" 2816 depends on MELAN 2817 select CHECK_SIGNATURE 2818 select NEW_LEDS 2819 select LEDS_CLASS 2820 help 2821 This option enables system support for the Technologic Systems TS-5500. 2822 2823endif # X86_32 2824 2825config AMD_NB 2826 def_bool y 2827 depends on CPU_SUP_AMD && PCI 2828 2829endmenu 2830 2831menu "Binary Emulations" 2832 2833config IA32_EMULATION 2834 bool "IA32 Emulation" 2835 depends on X86_64 2836 select ARCH_WANT_OLD_COMPAT_IPC 2837 select BINFMT_ELF 2838 select COMPAT_OLD_SIGACTION 2839 help 2840 Include code to run legacy 32-bit programs under a 2841 64-bit kernel. You should likely turn this on, unless you're 2842 100% sure that you don't have any 32-bit programs left. 2843 2844config X86_X32_ABI 2845 bool "x32 ABI for 64-bit mode" 2846 depends on X86_64 2847 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2848 # compressed debug sections to x86_x32 properly: 2849 # https://github.com/ClangBuiltLinux/linux/issues/514 2850 # https://github.com/ClangBuiltLinux/linux/issues/1141 2851 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 2852 help 2853 Include code to run binaries for the x32 native 32-bit ABI 2854 for 64-bit processors. An x32 process gets access to the 2855 full 64-bit register file and wide data path while leaving 2856 pointers at 32 bits for smaller memory footprint. 2857 2858config COMPAT_32 2859 def_bool y 2860 depends on IA32_EMULATION || X86_32 2861 select HAVE_UID16 2862 select OLD_SIGSUSPEND3 2863 2864config COMPAT 2865 def_bool y 2866 depends on IA32_EMULATION || X86_X32_ABI 2867 2868config COMPAT_FOR_U64_ALIGNMENT 2869 def_bool y 2870 depends on COMPAT 2871 2872endmenu 2873 2874config HAVE_ATOMIC_IOMAP 2875 def_bool y 2876 depends on X86_32 2877 2878source "arch/x86/kvm/Kconfig" 2879 2880source "arch/x86/Kconfig.assembler" 2881