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_DEBUG_VIRTUAL 73 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 74 select ARCH_HAS_DEVMEM_IS_ALLOWED 75 select ARCH_HAS_EARLY_DEBUG if KGDB 76 select ARCH_HAS_ELF_RANDOMIZE 77 select ARCH_HAS_FAST_MULTIPLIER 78 select ARCH_HAS_FILTER_PGPROT 79 select ARCH_HAS_FORTIFY_SOURCE 80 select ARCH_HAS_GCOV_PROFILE_ALL 81 select ARCH_HAS_KCOV if X86_64 82 select ARCH_HAS_MEM_ENCRYPT 83 select ARCH_HAS_MEMBARRIER_SYNC_CORE 84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 85 select ARCH_HAS_PMEM_API if X86_64 86 select ARCH_HAS_PTE_DEVMAP if X86_64 87 select ARCH_HAS_PTE_SPECIAL 88 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 89 select ARCH_HAS_COPY_MC if X86_64 90 select ARCH_HAS_SET_MEMORY 91 select ARCH_HAS_SET_DIRECT_MAP 92 select ARCH_HAS_STRICT_KERNEL_RWX 93 select ARCH_HAS_STRICT_MODULE_RWX 94 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 95 select ARCH_HAS_SYSCALL_WRAPPER 96 select ARCH_HAS_UBSAN_SANITIZE_ALL 97 select ARCH_HAS_DEBUG_WX 98 select ARCH_HAS_ZONE_DMA_SET if EXPERT 99 select ARCH_HAVE_NMI_SAFE_CMPXCHG 100 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 101 select ARCH_MIGHT_HAVE_PC_PARPORT 102 select ARCH_MIGHT_HAVE_PC_SERIO 103 select ARCH_STACKWALK 104 select ARCH_SUPPORTS_ACPI 105 select ARCH_SUPPORTS_ATOMIC_RMW 106 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 107 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 108 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 109 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 110 select ARCH_SUPPORTS_LTO_CLANG 111 select ARCH_SUPPORTS_LTO_CLANG_THIN 112 select ARCH_USE_BUILTIN_BSWAP 113 select ARCH_USE_MEMTEST 114 select ARCH_USE_QUEUED_RWLOCKS 115 select ARCH_USE_QUEUED_SPINLOCKS 116 select ARCH_USE_SYM_ANNOTATIONS 117 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 118 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 119 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 120 select ARCH_WANTS_NO_INSTR 121 select ARCH_WANT_HUGE_PMD_SHARE 122 select ARCH_WANT_LD_ORPHAN_WARN 123 select ARCH_WANTS_THP_SWAP if X86_64 124 select ARCH_HAS_PARANOID_L1D_FLUSH 125 select BUILDTIME_TABLE_SORT 126 select CLKEVT_I8253 127 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 128 select CLOCKSOURCE_WATCHDOG 129 select DCACHE_WORD_ACCESS 130 select DYNAMIC_SIGFRAME 131 select EDAC_ATOMIC_SCRUB 132 select EDAC_SUPPORT 133 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 134 select GENERIC_CLOCKEVENTS_MIN_ADJUST 135 select GENERIC_CMOS_UPDATE 136 select GENERIC_CPU_AUTOPROBE 137 select GENERIC_CPU_VULNERABILITIES 138 select GENERIC_EARLY_IOREMAP 139 select GENERIC_ENTRY 140 select GENERIC_IOMAP 141 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 142 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 143 select GENERIC_IRQ_MIGRATION if SMP 144 select GENERIC_IRQ_PROBE 145 select GENERIC_IRQ_RESERVATION_MODE 146 select GENERIC_IRQ_SHOW 147 select GENERIC_PENDING_IRQ if SMP 148 select GENERIC_PTDUMP 149 select GENERIC_SMP_IDLE_THREAD 150 select GENERIC_TIME_VSYSCALL 151 select GENERIC_GETTIMEOFDAY 152 select GENERIC_VDSO_TIME_NS 153 select GUP_GET_PTE_LOW_HIGH if X86_PAE 154 select HARDIRQS_SW_RESEND 155 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 156 select HAVE_ACPI_APEI if ACPI 157 select HAVE_ACPI_APEI_NMI if ACPI 158 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 159 select HAVE_ARCH_AUDITSYSCALL 160 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 161 select HAVE_ARCH_JUMP_LABEL 162 select HAVE_ARCH_JUMP_LABEL_RELATIVE 163 select HAVE_ARCH_KASAN if X86_64 164 select HAVE_ARCH_KASAN_VMALLOC if X86_64 165 select HAVE_ARCH_KFENCE 166 select HAVE_ARCH_KGDB 167 select HAVE_ARCH_MMAP_RND_BITS if MMU 168 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 169 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 170 select HAVE_ARCH_PREL32_RELOCATIONS 171 select HAVE_ARCH_SECCOMP_FILTER 172 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 173 select HAVE_ARCH_STACKLEAK 174 select HAVE_ARCH_TRACEHOOK 175 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 176 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 177 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 178 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 179 select HAVE_ARCH_VMAP_STACK if X86_64 180 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 181 select HAVE_ARCH_WITHIN_STACK_FRAMES 182 select HAVE_ASM_MODVERSIONS 183 select HAVE_CMPXCHG_DOUBLE 184 select HAVE_CMPXCHG_LOCAL 185 select HAVE_CONTEXT_TRACKING if X86_64 186 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING 187 select HAVE_C_RECORDMCOUNT 188 select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION 189 select HAVE_DEBUG_KMEMLEAK 190 select HAVE_DMA_CONTIGUOUS 191 select HAVE_DYNAMIC_FTRACE 192 select HAVE_DYNAMIC_FTRACE_WITH_REGS 193 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 194 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 195 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 196 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 197 select HAVE_EBPF_JIT 198 select HAVE_EFFICIENT_UNALIGNED_ACCESS 199 select HAVE_EISA 200 select HAVE_EXIT_THREAD 201 select HAVE_FAST_GUP 202 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 203 select HAVE_FTRACE_MCOUNT_RECORD 204 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 205 select HAVE_FUNCTION_TRACER 206 select HAVE_GCC_PLUGINS 207 select HAVE_HW_BREAKPOINT 208 select HAVE_IOREMAP_PROT 209 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 210 select HAVE_IRQ_TIME_ACCOUNTING 211 select HAVE_KERNEL_BZIP2 212 select HAVE_KERNEL_GZIP 213 select HAVE_KERNEL_LZ4 214 select HAVE_KERNEL_LZMA 215 select HAVE_KERNEL_LZO 216 select HAVE_KERNEL_XZ 217 select HAVE_KERNEL_ZSTD 218 select HAVE_KPROBES 219 select HAVE_KPROBES_ON_FTRACE 220 select HAVE_FUNCTION_ERROR_INJECTION 221 select HAVE_KRETPROBES 222 select HAVE_KVM 223 select HAVE_LIVEPATCH if X86_64 224 select HAVE_MIXED_BREAKPOINTS_REGS 225 select HAVE_MOD_ARCH_SPECIFIC 226 select HAVE_MOVE_PMD 227 select HAVE_MOVE_PUD 228 select HAVE_NMI 229 select HAVE_OPTPROBES 230 select HAVE_PCSPKR_PLATFORM 231 select HAVE_PERF_EVENTS 232 select HAVE_PERF_EVENTS_NMI 233 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 234 select HAVE_PCI 235 select HAVE_PERF_REGS 236 select HAVE_PERF_USER_STACK_DUMP 237 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 238 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 239 select HAVE_REGS_AND_STACK_ACCESS_API 240 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION 241 select HAVE_FUNCTION_ARG_ACCESS_API 242 select HAVE_SETUP_PER_CPU_AREA 243 select HAVE_SOFTIRQ_ON_OWN_STACK 244 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 245 select HAVE_STACK_VALIDATION if X86_64 246 select HAVE_STATIC_CALL 247 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION 248 select HAVE_PREEMPT_DYNAMIC 249 select HAVE_RSEQ 250 select HAVE_SYSCALL_TRACEPOINTS 251 select HAVE_UNSTABLE_SCHED_CLOCK 252 select HAVE_USER_RETURN_NOTIFIER 253 select HAVE_GENERIC_VDSO 254 select HOTPLUG_SMT if SMP 255 select IRQ_FORCED_THREADING 256 select NEED_PER_CPU_EMBED_FIRST_CHUNK 257 select NEED_PER_CPU_PAGE_FIRST_CHUNK 258 select NEED_SG_DMA_LENGTH 259 select PCI_DOMAINS if PCI 260 select PCI_LOCKLESS_CONFIG if PCI 261 select PERF_EVENTS 262 select RTC_LIB 263 select RTC_MC146818_LIB 264 select SPARSE_IRQ 265 select SRCU 266 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE) 267 select SYSCTL_EXCEPTION_TRACE 268 select THREAD_INFO_IN_TASK 269 select TRACE_IRQFLAGS_SUPPORT 270 select USER_STACKTRACE_SUPPORT 271 select VIRT_TO_BUS 272 select HAVE_ARCH_KCSAN if X86_64 273 select X86_FEATURE_NAMES if PROC_FS 274 select PROC_PID_ARCH_STATUS if PROC_FS 275 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 276 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 277 278config INSTRUCTION_DECODER 279 def_bool y 280 depends on KPROBES || PERF_EVENTS || UPROBES 281 282config OUTPUT_FORMAT 283 string 284 default "elf32-i386" if X86_32 285 default "elf64-x86-64" if X86_64 286 287config LOCKDEP_SUPPORT 288 def_bool y 289 290config STACKTRACE_SUPPORT 291 def_bool y 292 293config MMU 294 def_bool y 295 296config ARCH_MMAP_RND_BITS_MIN 297 default 28 if 64BIT 298 default 8 299 300config ARCH_MMAP_RND_BITS_MAX 301 default 32 if 64BIT 302 default 16 303 304config ARCH_MMAP_RND_COMPAT_BITS_MIN 305 default 8 306 307config ARCH_MMAP_RND_COMPAT_BITS_MAX 308 default 16 309 310config SBUS 311 bool 312 313config GENERIC_ISA_DMA 314 def_bool y 315 depends on ISA_DMA_API 316 317config GENERIC_BUG 318 def_bool y 319 depends on BUG 320 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 321 322config GENERIC_BUG_RELATIVE_POINTERS 323 bool 324 325config ARCH_MAY_HAVE_PC_FDC 326 def_bool y 327 depends on ISA_DMA_API 328 329config GENERIC_CALIBRATE_DELAY 330 def_bool y 331 332config ARCH_HAS_CPU_RELAX 333 def_bool y 334 335config ARCH_HAS_FILTER_PGPROT 336 def_bool y 337 338config ARCH_HIBERNATION_POSSIBLE 339 def_bool y 340 341config ARCH_NR_GPIO 342 int 343 default 1024 if X86_64 344 default 512 345 346config ARCH_SUSPEND_POSSIBLE 347 def_bool y 348 349config ARCH_WANT_GENERAL_HUGETLB 350 def_bool y 351 352config AUDIT_ARCH 353 def_bool y if X86_64 354 355config KASAN_SHADOW_OFFSET 356 hex 357 depends on KASAN 358 default 0xdffffc0000000000 359 360config HAVE_INTEL_TXT 361 def_bool y 362 depends on INTEL_IOMMU && ACPI 363 364config X86_32_SMP 365 def_bool y 366 depends on X86_32 && SMP 367 368config X86_64_SMP 369 def_bool y 370 depends on X86_64 && SMP 371 372config ARCH_SUPPORTS_UPROBES 373 def_bool y 374 375config FIX_EARLYCON_MEM 376 def_bool y 377 378config DYNAMIC_PHYSICAL_MASK 379 bool 380 381config PGTABLE_LEVELS 382 int 383 default 5 if X86_5LEVEL 384 default 4 if X86_64 385 default 3 if X86_PAE 386 default 2 387 388config CC_HAS_SANE_STACKPROTECTOR 389 bool 390 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT 391 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC)) 392 help 393 We have to make sure stack protector is unconditionally disabled if 394 the compiler produces broken code or if it does not let us control 395 the segment on 32-bit kernels. 396 397menu "Processor type and features" 398 399config SMP 400 bool "Symmetric multi-processing support" 401 help 402 This enables support for systems with more than one CPU. If you have 403 a system with only one CPU, say N. If you have a system with more 404 than one CPU, say Y. 405 406 If you say N here, the kernel will run on uni- and multiprocessor 407 machines, but will use only one CPU of a multiprocessor machine. If 408 you say Y here, the kernel will run on many, but not all, 409 uniprocessor machines. On a uniprocessor machine, the kernel 410 will run faster if you say N here. 411 412 Note that if you say Y here and choose architecture "586" or 413 "Pentium" under "Processor family", the kernel will not work on 486 414 architectures. Similarly, multiprocessor kernels for the "PPro" 415 architecture may not work on all Pentium based boards. 416 417 People using multiprocessor machines who say Y here should also say 418 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 419 Management" code will be disabled if you say Y here. 420 421 See also <file:Documentation/x86/i386/IO-APIC.rst>, 422 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 423 <http://www.tldp.org/docs.html#howto>. 424 425 If you don't know what to do here, say N. 426 427config X86_FEATURE_NAMES 428 bool "Processor feature human-readable names" if EMBEDDED 429 default y 430 help 431 This option compiles in a table of x86 feature bits and corresponding 432 names. This is required to support /proc/cpuinfo and a few kernel 433 messages. You can disable this to save space, at the expense of 434 making those few kernel messages show numeric feature bits instead. 435 436 If in doubt, say Y. 437 438config X86_X2APIC 439 bool "Support x2apic" 440 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 441 help 442 This enables x2apic support on CPUs that have this feature. 443 444 This allows 32-bit apic IDs (so it can support very large systems), 445 and accesses the local apic via MSRs not via mmio. 446 447 If you don't know what to do here, say N. 448 449config X86_MPPARSE 450 bool "Enable MPS table" if ACPI 451 default y 452 depends on X86_LOCAL_APIC 453 help 454 For old smp systems that do not have proper acpi support. Newer systems 455 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 456 457config GOLDFISH 458 def_bool y 459 depends on X86_GOLDFISH 460 461config RETPOLINE 462 bool "Avoid speculative indirect branches in kernel" 463 default y 464 help 465 Compile kernel with the retpoline compiler options to guard against 466 kernel-to-user data leaks by avoiding speculative indirect 467 branches. Requires a compiler with -mindirect-branch=thunk-extern 468 support for full protection. The kernel may run slower. 469 470config CC_HAS_SLS 471 def_bool $(cc-option,-mharden-sls=all) 472 473config SLS 474 bool "Mitigate Straight-Line-Speculation" 475 depends on CC_HAS_SLS && X86_64 476 default n 477 help 478 Compile the kernel with straight-line-speculation options to guard 479 against straight line speculation. The kernel image might be slightly 480 larger. 481 482config X86_CPU_RESCTRL 483 bool "x86 CPU resource control support" 484 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 485 select KERNFS 486 select PROC_CPU_RESCTRL if PROC_FS 487 help 488 Enable x86 CPU resource control support. 489 490 Provide support for the allocation and monitoring of system resources 491 usage by the CPU. 492 493 Intel calls this Intel Resource Director Technology 494 (Intel(R) RDT). More information about RDT can be found in the 495 Intel x86 Architecture Software Developer Manual. 496 497 AMD calls this AMD Platform Quality of Service (AMD QoS). 498 More information about AMD QoS can be found in the AMD64 Technology 499 Platform Quality of Service Extensions manual. 500 501 Say N if unsure. 502 503if X86_32 504config X86_BIGSMP 505 bool "Support for big SMP systems with more than 8 CPUs" 506 depends on SMP 507 help 508 This option is needed for the systems that have more than 8 CPUs. 509 510config X86_EXTENDED_PLATFORM 511 bool "Support for extended (non-PC) x86 platforms" 512 default y 513 help 514 If you disable this option then the kernel will only support 515 standard PC platforms. (which covers the vast majority of 516 systems out there.) 517 518 If you enable this option then you'll be able to select support 519 for the following (non-PC) 32 bit x86 platforms: 520 Goldfish (Android emulator) 521 AMD Elan 522 RDC R-321x SoC 523 SGI 320/540 (Visual Workstation) 524 STA2X11-based (e.g. Northville) 525 Moorestown MID devices 526 527 If you have one of these systems, or if you want to build a 528 generic distribution kernel, say Y here - otherwise say N. 529endif 530 531if X86_64 532config X86_EXTENDED_PLATFORM 533 bool "Support for extended (non-PC) x86 platforms" 534 default y 535 help 536 If you disable this option then the kernel will only support 537 standard PC platforms. (which covers the vast majority of 538 systems out there.) 539 540 If you enable this option then you'll be able to select support 541 for the following (non-PC) 64 bit x86 platforms: 542 Numascale NumaChip 543 ScaleMP vSMP 544 SGI Ultraviolet 545 546 If you have one of these systems, or if you want to build a 547 generic distribution kernel, say Y here - otherwise say N. 548endif 549# This is an alphabetically sorted list of 64 bit extended platforms 550# Please maintain the alphabetic order if and when there are additions 551config X86_NUMACHIP 552 bool "Numascale NumaChip" 553 depends on X86_64 554 depends on X86_EXTENDED_PLATFORM 555 depends on NUMA 556 depends on SMP 557 depends on X86_X2APIC 558 depends on PCI_MMCONFIG 559 help 560 Adds support for Numascale NumaChip large-SMP systems. Needed to 561 enable more than ~168 cores. 562 If you don't have one of these, you should say N here. 563 564config X86_VSMP 565 bool "ScaleMP vSMP" 566 select HYPERVISOR_GUEST 567 select PARAVIRT 568 depends on X86_64 && PCI 569 depends on X86_EXTENDED_PLATFORM 570 depends on SMP 571 help 572 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 573 supposed to run on these EM64T-based machines. Only choose this option 574 if you have one of these machines. 575 576config X86_UV 577 bool "SGI Ultraviolet" 578 depends on X86_64 579 depends on X86_EXTENDED_PLATFORM 580 depends on NUMA 581 depends on EFI 582 depends on KEXEC_CORE 583 depends on X86_X2APIC 584 depends on PCI 585 help 586 This option is needed in order to support SGI Ultraviolet systems. 587 If you don't have one of these, you should say N here. 588 589# Following is an alphabetically sorted list of 32 bit extended platforms 590# Please maintain the alphabetic order if and when there are additions 591 592config X86_GOLDFISH 593 bool "Goldfish (Virtual Platform)" 594 depends on X86_EXTENDED_PLATFORM 595 help 596 Enable support for the Goldfish virtual platform used primarily 597 for Android development. Unless you are building for the Android 598 Goldfish emulator say N here. 599 600config X86_INTEL_CE 601 bool "CE4100 TV platform" 602 depends on PCI 603 depends on PCI_GODIRECT 604 depends on X86_IO_APIC 605 depends on X86_32 606 depends on X86_EXTENDED_PLATFORM 607 select X86_REBOOTFIXUPS 608 select OF 609 select OF_EARLY_FLATTREE 610 help 611 Select for the Intel CE media processor (CE4100) SOC. 612 This option compiles in support for the CE4100 SOC for settop 613 boxes and media devices. 614 615config X86_INTEL_MID 616 bool "Intel MID platform support" 617 depends on X86_EXTENDED_PLATFORM 618 depends on X86_PLATFORM_DEVICES 619 depends on PCI 620 depends on X86_64 || (PCI_GOANY && X86_32) 621 depends on X86_IO_APIC 622 select I2C 623 select DW_APB_TIMER 624 select INTEL_SCU_PCI 625 help 626 Select to build a kernel capable of supporting Intel MID (Mobile 627 Internet Device) platform systems which do not have the PCI legacy 628 interfaces. If you are building for a PC class system say N here. 629 630 Intel MID platforms are based on an Intel processor and chipset which 631 consume less power than most of the x86 derivatives. 632 633config X86_INTEL_QUARK 634 bool "Intel Quark platform support" 635 depends on X86_32 636 depends on X86_EXTENDED_PLATFORM 637 depends on X86_PLATFORM_DEVICES 638 depends on X86_TSC 639 depends on PCI 640 depends on PCI_GOANY 641 depends on X86_IO_APIC 642 select IOSF_MBI 643 select INTEL_IMR 644 select COMMON_CLK 645 help 646 Select to include support for Quark X1000 SoC. 647 Say Y here if you have a Quark based system such as the Arduino 648 compatible Intel Galileo. 649 650config X86_INTEL_LPSS 651 bool "Intel Low Power Subsystem Support" 652 depends on X86 && ACPI && PCI 653 select COMMON_CLK 654 select PINCTRL 655 select IOSF_MBI 656 help 657 Select to build support for Intel Low Power Subsystem such as 658 found on Intel Lynxpoint PCH. Selecting this option enables 659 things like clock tree (common clock framework) and pincontrol 660 which are needed by the LPSS peripheral drivers. 661 662config X86_AMD_PLATFORM_DEVICE 663 bool "AMD ACPI2Platform devices support" 664 depends on ACPI 665 select COMMON_CLK 666 select PINCTRL 667 help 668 Select to interpret AMD specific ACPI device to platform device 669 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 670 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 671 implemented under PINCTRL subsystem. 672 673config IOSF_MBI 674 tristate "Intel SoC IOSF Sideband support for SoC platforms" 675 depends on PCI 676 help 677 This option enables sideband register access support for Intel SoC 678 platforms. On these platforms the IOSF sideband is used in lieu of 679 MSR's for some register accesses, mostly but not limited to thermal 680 and power. Drivers may query the availability of this device to 681 determine if they need the sideband in order to work on these 682 platforms. The sideband is available on the following SoC products. 683 This list is not meant to be exclusive. 684 - BayTrail 685 - Braswell 686 - Quark 687 688 You should say Y if you are running a kernel on one of these SoC's. 689 690config IOSF_MBI_DEBUG 691 bool "Enable IOSF sideband access through debugfs" 692 depends on IOSF_MBI && DEBUG_FS 693 help 694 Select this option to expose the IOSF sideband access registers (MCR, 695 MDR, MCRX) through debugfs to write and read register information from 696 different units on the SoC. This is most useful for obtaining device 697 state information for debug and analysis. As this is a general access 698 mechanism, users of this option would have specific knowledge of the 699 device they want to access. 700 701 If you don't require the option or are in doubt, say N. 702 703config X86_RDC321X 704 bool "RDC R-321x SoC" 705 depends on X86_32 706 depends on X86_EXTENDED_PLATFORM 707 select M486 708 select X86_REBOOTFIXUPS 709 help 710 This option is needed for RDC R-321x system-on-chip, also known 711 as R-8610-(G). 712 If you don't have one of these chips, you should say N here. 713 714config X86_32_NON_STANDARD 715 bool "Support non-standard 32-bit SMP architectures" 716 depends on X86_32 && SMP 717 depends on X86_EXTENDED_PLATFORM 718 help 719 This option compiles in the bigsmp and STA2X11 default 720 subarchitectures. It is intended for a generic binary 721 kernel. If you select them all, kernel will probe it one by 722 one and will fallback to default. 723 724# Alphabetically sorted list of Non standard 32 bit platforms 725 726config X86_SUPPORTS_MEMORY_FAILURE 727 def_bool y 728 # MCE code calls memory_failure(): 729 depends on X86_MCE 730 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 731 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 732 depends on X86_64 || !SPARSEMEM 733 select ARCH_SUPPORTS_MEMORY_FAILURE 734 735config STA2X11 736 bool "STA2X11 Companion Chip Support" 737 depends on X86_32_NON_STANDARD && PCI 738 select SWIOTLB 739 select MFD_STA2X11 740 select GPIOLIB 741 help 742 This adds support for boards based on the STA2X11 IO-Hub, 743 a.k.a. "ConneXt". The chip is used in place of the standard 744 PC chipset, so all "standard" peripherals are missing. If this 745 option is selected the kernel will still be able to boot on 746 standard PC machines. 747 748config X86_32_IRIS 749 tristate "Eurobraille/Iris poweroff module" 750 depends on X86_32 751 help 752 The Iris machines from EuroBraille do not have APM or ACPI support 753 to shut themselves down properly. A special I/O sequence is 754 needed to do so, which is what this module does at 755 kernel shutdown. 756 757 This is only for Iris machines from EuroBraille. 758 759 If unused, say N. 760 761config SCHED_OMIT_FRAME_POINTER 762 def_bool y 763 prompt "Single-depth WCHAN output" 764 depends on X86 765 help 766 Calculate simpler /proc/<PID>/wchan values. If this option 767 is disabled then wchan values will recurse back to the 768 caller function. This provides more accurate wchan values, 769 at the expense of slightly more scheduling overhead. 770 771 If in doubt, say "Y". 772 773menuconfig HYPERVISOR_GUEST 774 bool "Linux guest support" 775 help 776 Say Y here to enable options for running Linux under various hyper- 777 visors. This option enables basic hypervisor detection and platform 778 setup. 779 780 If you say N, all options in this submenu will be skipped and 781 disabled, and Linux guest support won't be built in. 782 783if HYPERVISOR_GUEST 784 785config PARAVIRT 786 bool "Enable paravirtualization code" 787 depends on HAVE_STATIC_CALL 788 help 789 This changes the kernel so it can modify itself when it is run 790 under a hypervisor, potentially improving performance significantly 791 over full virtualization. However, when run without a hypervisor 792 the kernel is theoretically slower and slightly larger. 793 794config PARAVIRT_XXL 795 bool 796 797config PARAVIRT_DEBUG 798 bool "paravirt-ops debugging" 799 depends on PARAVIRT && DEBUG_KERNEL 800 help 801 Enable to debug paravirt_ops internals. Specifically, BUG if 802 a paravirt_op is missing when it is called. 803 804config PARAVIRT_SPINLOCKS 805 bool "Paravirtualization layer for spinlocks" 806 depends on PARAVIRT && SMP 807 help 808 Paravirtualized spinlocks allow a pvops backend to replace the 809 spinlock implementation with something virtualization-friendly 810 (for example, block the virtual CPU rather than spinning). 811 812 It has a minimal impact on native kernels and gives a nice performance 813 benefit on paravirtualized KVM / Xen kernels. 814 815 If you are unsure how to answer this question, answer Y. 816 817config X86_HV_CALLBACK_VECTOR 818 def_bool n 819 820source "arch/x86/xen/Kconfig" 821 822config KVM_GUEST 823 bool "KVM Guest support (including kvmclock)" 824 depends on PARAVIRT 825 select PARAVIRT_CLOCK 826 select ARCH_CPUIDLE_HALTPOLL 827 select X86_HV_CALLBACK_VECTOR 828 default y 829 help 830 This option enables various optimizations for running under the KVM 831 hypervisor. It includes a paravirtualized clock, so that instead 832 of relying on a PIT (or probably other) emulation by the 833 underlying device model, the host provides the guest with 834 timing infrastructure such as time of day, and system time 835 836config ARCH_CPUIDLE_HALTPOLL 837 def_bool n 838 prompt "Disable host haltpoll when loading haltpoll driver" 839 help 840 If virtualized under KVM, disable host haltpoll. 841 842config PVH 843 bool "Support for running PVH guests" 844 help 845 This option enables the PVH entry point for guest virtual machines 846 as specified in the x86/HVM direct boot ABI. 847 848config PARAVIRT_TIME_ACCOUNTING 849 bool "Paravirtual steal time accounting" 850 depends on PARAVIRT 851 help 852 Select this option to enable fine granularity task steal time 853 accounting. Time spent executing other tasks in parallel with 854 the current vCPU is discounted from the vCPU power. To account for 855 that, there can be a small performance impact. 856 857 If in doubt, say N here. 858 859config PARAVIRT_CLOCK 860 bool 861 862config JAILHOUSE_GUEST 863 bool "Jailhouse non-root cell support" 864 depends on X86_64 && PCI 865 select X86_PM_TIMER 866 help 867 This option allows to run Linux as guest in a Jailhouse non-root 868 cell. You can leave this option disabled if you only want to start 869 Jailhouse and run Linux afterwards in the root cell. 870 871config ACRN_GUEST 872 bool "ACRN Guest support" 873 depends on X86_64 874 select X86_HV_CALLBACK_VECTOR 875 help 876 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 877 a flexible, lightweight reference open-source hypervisor, built with 878 real-time and safety-criticality in mind. It is built for embedded 879 IOT with small footprint and real-time features. More details can be 880 found in https://projectacrn.org/. 881 882endif #HYPERVISOR_GUEST 883 884source "arch/x86/Kconfig.cpu" 885 886config HPET_TIMER 887 def_bool X86_64 888 prompt "HPET Timer Support" if X86_32 889 help 890 Use the IA-PC HPET (High Precision Event Timer) to manage 891 time in preference to the PIT and RTC, if a HPET is 892 present. 893 HPET is the next generation timer replacing legacy 8254s. 894 The HPET provides a stable time base on SMP 895 systems, unlike the TSC, but it is more expensive to access, 896 as it is off-chip. The interface used is documented 897 in the HPET spec, revision 1. 898 899 You can safely choose Y here. However, HPET will only be 900 activated if the platform and the BIOS support this feature. 901 Otherwise the 8254 will be used for timing services. 902 903 Choose N to continue using the legacy 8254 timer. 904 905config HPET_EMULATE_RTC 906 def_bool y 907 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 908 909# Mark as expert because too many people got it wrong. 910# The code disables itself when not needed. 911config DMI 912 default y 913 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 914 bool "Enable DMI scanning" if EXPERT 915 help 916 Enabled scanning of DMI to identify machine quirks. Say Y 917 here unless you have verified that your setup is not 918 affected by entries in the DMI blacklist. Required by PNP 919 BIOS code. 920 921config GART_IOMMU 922 bool "Old AMD GART IOMMU support" 923 select DMA_OPS 924 select IOMMU_HELPER 925 select SWIOTLB 926 depends on X86_64 && PCI && AMD_NB 927 help 928 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 929 GART based hardware IOMMUs. 930 931 The GART supports full DMA access for devices with 32-bit access 932 limitations, on systems with more than 3 GB. This is usually needed 933 for USB, sound, many IDE/SATA chipsets and some other devices. 934 935 Newer systems typically have a modern AMD IOMMU, supported via 936 the CONFIG_AMD_IOMMU=y config option. 937 938 In normal configurations this driver is only active when needed: 939 there's more than 3 GB of memory and the system contains a 940 32-bit limited device. 941 942 If unsure, say Y. 943 944config MAXSMP 945 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 946 depends on X86_64 && SMP && DEBUG_KERNEL 947 select CPUMASK_OFFSTACK 948 help 949 Enable maximum number of CPUS and NUMA Nodes for this architecture. 950 If unsure, say N. 951 952# 953# The maximum number of CPUs supported: 954# 955# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 956# and which can be configured interactively in the 957# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 958# 959# The ranges are different on 32-bit and 64-bit kernels, depending on 960# hardware capabilities and scalability features of the kernel. 961# 962# ( If MAXSMP is enabled we just use the highest possible value and disable 963# interactive configuration. ) 964# 965 966config NR_CPUS_RANGE_BEGIN 967 int 968 default NR_CPUS_RANGE_END if MAXSMP 969 default 1 if !SMP 970 default 2 971 972config NR_CPUS_RANGE_END 973 int 974 depends on X86_32 975 default 64 if SMP && X86_BIGSMP 976 default 8 if SMP && !X86_BIGSMP 977 default 1 if !SMP 978 979config NR_CPUS_RANGE_END 980 int 981 depends on X86_64 982 default 8192 if SMP && CPUMASK_OFFSTACK 983 default 512 if SMP && !CPUMASK_OFFSTACK 984 default 1 if !SMP 985 986config NR_CPUS_DEFAULT 987 int 988 depends on X86_32 989 default 32 if X86_BIGSMP 990 default 8 if SMP 991 default 1 if !SMP 992 993config NR_CPUS_DEFAULT 994 int 995 depends on X86_64 996 default 8192 if MAXSMP 997 default 64 if SMP 998 default 1 if !SMP 999 1000config NR_CPUS 1001 int "Maximum number of CPUs" if SMP && !MAXSMP 1002 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1003 default NR_CPUS_DEFAULT 1004 help 1005 This allows you to specify the maximum number of CPUs which this 1006 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1007 supported value is 8192, otherwise the maximum value is 512. The 1008 minimum value which makes sense is 2. 1009 1010 This is purely to save memory: each supported CPU adds about 8KB 1011 to the kernel image. 1012 1013config SCHED_CLUSTER 1014 bool "Cluster scheduler support" 1015 depends on SMP 1016 default y 1017 help 1018 Cluster scheduler support improves the CPU scheduler's decision 1019 making when dealing with machines that have clusters of CPUs. 1020 Cluster usually means a couple of CPUs which are placed closely 1021 by sharing mid-level caches, last-level cache tags or internal 1022 busses. 1023 1024config SCHED_SMT 1025 def_bool y if SMP 1026 1027config SCHED_MC 1028 def_bool y 1029 prompt "Multi-core scheduler support" 1030 depends on SMP 1031 help 1032 Multi-core scheduler support improves the CPU scheduler's decision 1033 making when dealing with multi-core CPU chips at a cost of slightly 1034 increased overhead in some places. If unsure say N here. 1035 1036config SCHED_MC_PRIO 1037 bool "CPU core priorities scheduler support" 1038 depends on SCHED_MC && CPU_SUP_INTEL 1039 select X86_INTEL_PSTATE 1040 select CPU_FREQ 1041 default y 1042 help 1043 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1044 core ordering determined at manufacturing time, which allows 1045 certain cores to reach higher turbo frequencies (when running 1046 single threaded workloads) than others. 1047 1048 Enabling this kernel feature teaches the scheduler about 1049 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1050 scheduler's CPU selection logic accordingly, so that higher 1051 overall system performance can be achieved. 1052 1053 This feature will have no effect on CPUs without this feature. 1054 1055 If unsure say Y here. 1056 1057config UP_LATE_INIT 1058 def_bool y 1059 depends on !SMP && X86_LOCAL_APIC 1060 1061config X86_UP_APIC 1062 bool "Local APIC support on uniprocessors" if !PCI_MSI 1063 default PCI_MSI 1064 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1065 help 1066 A local APIC (Advanced Programmable Interrupt Controller) is an 1067 integrated interrupt controller in the CPU. If you have a single-CPU 1068 system which has a processor with a local APIC, you can say Y here to 1069 enable and use it. If you say Y here even though your machine doesn't 1070 have a local APIC, then the kernel will still run with no slowdown at 1071 all. The local APIC supports CPU-generated self-interrupts (timer, 1072 performance counters), and the NMI watchdog which detects hard 1073 lockups. 1074 1075config X86_UP_IOAPIC 1076 bool "IO-APIC support on uniprocessors" 1077 depends on X86_UP_APIC 1078 help 1079 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1080 SMP-capable replacement for PC-style interrupt controllers. Most 1081 SMP systems and many recent uniprocessor systems have one. 1082 1083 If you have a single-CPU system with an IO-APIC, you can say Y here 1084 to use it. If you say Y here even though your machine doesn't have 1085 an IO-APIC, then the kernel will still run with no slowdown at all. 1086 1087config X86_LOCAL_APIC 1088 def_bool y 1089 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1090 select IRQ_DOMAIN_HIERARCHY 1091 select PCI_MSI_IRQ_DOMAIN if PCI_MSI 1092 1093config X86_IO_APIC 1094 def_bool y 1095 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1096 1097config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1098 bool "Reroute for broken boot IRQs" 1099 depends on X86_IO_APIC 1100 help 1101 This option enables a workaround that fixes a source of 1102 spurious interrupts. This is recommended when threaded 1103 interrupt handling is used on systems where the generation of 1104 superfluous "boot interrupts" cannot be disabled. 1105 1106 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1107 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1108 kernel does during interrupt handling). On chipsets where this 1109 boot IRQ generation cannot be disabled, this workaround keeps 1110 the original IRQ line masked so that only the equivalent "boot 1111 IRQ" is delivered to the CPUs. The workaround also tells the 1112 kernel to set up the IRQ handler on the boot IRQ line. In this 1113 way only one interrupt is delivered to the kernel. Otherwise 1114 the spurious second interrupt may cause the kernel to bring 1115 down (vital) interrupt lines. 1116 1117 Only affects "broken" chipsets. Interrupt sharing may be 1118 increased on these systems. 1119 1120config X86_MCE 1121 bool "Machine Check / overheating reporting" 1122 select GENERIC_ALLOCATOR 1123 default y 1124 help 1125 Machine Check support allows the processor to notify the 1126 kernel if it detects a problem (e.g. overheating, data corruption). 1127 The action the kernel takes depends on the severity of the problem, 1128 ranging from warning messages to halting the machine. 1129 1130config X86_MCELOG_LEGACY 1131 bool "Support for deprecated /dev/mcelog character device" 1132 depends on X86_MCE 1133 help 1134 Enable support for /dev/mcelog which is needed by the old mcelog 1135 userspace logging daemon. Consider switching to the new generation 1136 rasdaemon solution. 1137 1138config X86_MCE_INTEL 1139 def_bool y 1140 prompt "Intel MCE features" 1141 depends on X86_MCE && X86_LOCAL_APIC 1142 help 1143 Additional support for intel specific MCE features such as 1144 the thermal monitor. 1145 1146config X86_MCE_AMD 1147 def_bool y 1148 prompt "AMD MCE features" 1149 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1150 help 1151 Additional support for AMD specific MCE features such as 1152 the DRAM Error Threshold. 1153 1154config X86_ANCIENT_MCE 1155 bool "Support for old Pentium 5 / WinChip machine checks" 1156 depends on X86_32 && X86_MCE 1157 help 1158 Include support for machine check handling on old Pentium 5 or WinChip 1159 systems. These typically need to be enabled explicitly on the command 1160 line. 1161 1162config X86_MCE_THRESHOLD 1163 depends on X86_MCE_AMD || X86_MCE_INTEL 1164 def_bool y 1165 1166config X86_MCE_INJECT 1167 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1168 tristate "Machine check injector support" 1169 help 1170 Provide support for injecting machine checks for testing purposes. 1171 If you don't know what a machine check is and you don't do kernel 1172 QA it is safe to say n. 1173 1174source "arch/x86/events/Kconfig" 1175 1176config X86_LEGACY_VM86 1177 bool "Legacy VM86 support" 1178 depends on X86_32 1179 help 1180 This option allows user programs to put the CPU into V8086 1181 mode, which is an 80286-era approximation of 16-bit real mode. 1182 1183 Some very old versions of X and/or vbetool require this option 1184 for user mode setting. Similarly, DOSEMU will use it if 1185 available to accelerate real mode DOS programs. However, any 1186 recent version of DOSEMU, X, or vbetool should be fully 1187 functional even without kernel VM86 support, as they will all 1188 fall back to software emulation. Nevertheless, if you are using 1189 a 16-bit DOS program where 16-bit performance matters, vm86 1190 mode might be faster than emulation and you might want to 1191 enable this option. 1192 1193 Note that any app that works on a 64-bit kernel is unlikely to 1194 need this option, as 64-bit kernels don't, and can't, support 1195 V8086 mode. This option is also unrelated to 16-bit protected 1196 mode and is not needed to run most 16-bit programs under Wine. 1197 1198 Enabling this option increases the complexity of the kernel 1199 and slows down exception handling a tiny bit. 1200 1201 If unsure, say N here. 1202 1203config VM86 1204 bool 1205 default X86_LEGACY_VM86 1206 1207config X86_16BIT 1208 bool "Enable support for 16-bit segments" if EXPERT 1209 default y 1210 depends on MODIFY_LDT_SYSCALL 1211 help 1212 This option is required by programs like Wine to run 16-bit 1213 protected mode legacy code on x86 processors. Disabling 1214 this option saves about 300 bytes on i386, or around 6K text 1215 plus 16K runtime memory on x86-64, 1216 1217config X86_ESPFIX32 1218 def_bool y 1219 depends on X86_16BIT && X86_32 1220 1221config X86_ESPFIX64 1222 def_bool y 1223 depends on X86_16BIT && X86_64 1224 1225config X86_VSYSCALL_EMULATION 1226 bool "Enable vsyscall emulation" if EXPERT 1227 default y 1228 depends on X86_64 1229 help 1230 This enables emulation of the legacy vsyscall page. Disabling 1231 it is roughly equivalent to booting with vsyscall=none, except 1232 that it will also disable the helpful warning if a program 1233 tries to use a vsyscall. With this option set to N, offending 1234 programs will just segfault, citing addresses of the form 1235 0xffffffffff600?00. 1236 1237 This option is required by many programs built before 2013, and 1238 care should be used even with newer programs if set to N. 1239 1240 Disabling this option saves about 7K of kernel size and 1241 possibly 4K of additional runtime pagetable memory. 1242 1243config X86_IOPL_IOPERM 1244 bool "IOPERM and IOPL Emulation" 1245 default y 1246 help 1247 This enables the ioperm() and iopl() syscalls which are necessary 1248 for legacy applications. 1249 1250 Legacy IOPL support is an overbroad mechanism which allows user 1251 space aside of accessing all 65536 I/O ports also to disable 1252 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1253 capabilities and permission from potentially active security 1254 modules. 1255 1256 The emulation restricts the functionality of the syscall to 1257 only allowing the full range I/O port access, but prevents the 1258 ability to disable interrupts from user space which would be 1259 granted if the hardware IOPL mechanism would be used. 1260 1261config TOSHIBA 1262 tristate "Toshiba Laptop support" 1263 depends on X86_32 1264 help 1265 This adds a driver to safely access the System Management Mode of 1266 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1267 not work on models with a Phoenix BIOS. The System Management Mode 1268 is used to set the BIOS and power saving options on Toshiba portables. 1269 1270 For information on utilities to make use of this driver see the 1271 Toshiba Linux utilities web site at: 1272 <http://www.buzzard.org.uk/toshiba/>. 1273 1274 Say Y if you intend to run this kernel on a Toshiba portable. 1275 Say N otherwise. 1276 1277config I8K 1278 tristate "Dell i8k legacy laptop support" 1279 depends on HWMON 1280 depends on PROC_FS 1281 select SENSORS_DELL_SMM 1282 help 1283 This option enables legacy /proc/i8k userspace interface in hwmon 1284 dell-smm-hwmon driver. Character file /proc/i8k reports bios version, 1285 temperature and allows controlling fan speeds of Dell laptops via 1286 System Management Mode. For old Dell laptops (like Dell Inspiron 8000) 1287 it reports also power and hotkey status. For fan speed control is 1288 needed userspace package i8kutils. 1289 1290 Say Y if you intend to run this kernel on old Dell laptops or want to 1291 use userspace package i8kutils. 1292 Say N otherwise. 1293 1294config X86_REBOOTFIXUPS 1295 bool "Enable X86 board specific fixups for reboot" 1296 depends on X86_32 1297 help 1298 This enables chipset and/or board specific fixups to be done 1299 in order to get reboot to work correctly. This is only needed on 1300 some combinations of hardware and BIOS. The symptom, for which 1301 this config is intended, is when reboot ends with a stalled/hung 1302 system. 1303 1304 Currently, the only fixup is for the Geode machines using 1305 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1306 1307 Say Y if you want to enable the fixup. Currently, it's safe to 1308 enable this option even if you don't need it. 1309 Say N otherwise. 1310 1311config MICROCODE 1312 bool "CPU microcode loading support" 1313 default y 1314 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1315 help 1316 If you say Y here, you will be able to update the microcode on 1317 Intel and AMD processors. The Intel support is for the IA32 family, 1318 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1319 AMD support is for families 0x10 and later. You will obviously need 1320 the actual microcode binary data itself which is not shipped with 1321 the Linux kernel. 1322 1323 The preferred method to load microcode from a detached initrd is described 1324 in Documentation/x86/microcode.rst. For that you need to enable 1325 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1326 initrd for microcode blobs. 1327 1328 In addition, you can build the microcode into the kernel. For that you 1329 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1330 config option. 1331 1332config MICROCODE_INTEL 1333 bool "Intel microcode loading support" 1334 depends on MICROCODE 1335 default MICROCODE 1336 help 1337 This options enables microcode patch loading support for Intel 1338 processors. 1339 1340 For the current Intel microcode data package go to 1341 <https://downloadcenter.intel.com> and search for 1342 'Linux Processor Microcode Data File'. 1343 1344config MICROCODE_AMD 1345 bool "AMD microcode loading support" 1346 depends on MICROCODE 1347 help 1348 If you select this option, microcode patch loading support for AMD 1349 processors will be enabled. 1350 1351config MICROCODE_OLD_INTERFACE 1352 bool "Ancient loading interface (DEPRECATED)" 1353 default n 1354 depends on MICROCODE 1355 help 1356 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface 1357 which was used by userspace tools like iucode_tool and microcode.ctl. 1358 It is inadequate because it runs too late to be able to properly 1359 load microcode on a machine and it needs special tools. Instead, you 1360 should've switched to the early loading method with the initrd or 1361 builtin microcode by now: Documentation/x86/microcode.rst 1362 1363config X86_MSR 1364 tristate "/dev/cpu/*/msr - Model-specific register support" 1365 help 1366 This device gives privileged processes access to the x86 1367 Model-Specific Registers (MSRs). It is a character device with 1368 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1369 MSR accesses are directed to a specific CPU on multi-processor 1370 systems. 1371 1372config X86_CPUID 1373 tristate "/dev/cpu/*/cpuid - CPU information support" 1374 help 1375 This device gives processes access to the x86 CPUID instruction to 1376 be executed on a specific processor. It is a character device 1377 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1378 /dev/cpu/31/cpuid. 1379 1380choice 1381 prompt "High Memory Support" 1382 default HIGHMEM4G 1383 depends on X86_32 1384 1385config NOHIGHMEM 1386 bool "off" 1387 help 1388 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1389 However, the address space of 32-bit x86 processors is only 4 1390 Gigabytes large. That means that, if you have a large amount of 1391 physical memory, not all of it can be "permanently mapped" by the 1392 kernel. The physical memory that's not permanently mapped is called 1393 "high memory". 1394 1395 If you are compiling a kernel which will never run on a machine with 1396 more than 1 Gigabyte total physical RAM, answer "off" here (default 1397 choice and suitable for most users). This will result in a "3GB/1GB" 1398 split: 3GB are mapped so that each process sees a 3GB virtual memory 1399 space and the remaining part of the 4GB virtual memory space is used 1400 by the kernel to permanently map as much physical memory as 1401 possible. 1402 1403 If the machine has between 1 and 4 Gigabytes physical RAM, then 1404 answer "4GB" here. 1405 1406 If more than 4 Gigabytes is used then answer "64GB" here. This 1407 selection turns Intel PAE (Physical Address Extension) mode on. 1408 PAE implements 3-level paging on IA32 processors. PAE is fully 1409 supported by Linux, PAE mode is implemented on all recent Intel 1410 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1411 then the kernel will not boot on CPUs that don't support PAE! 1412 1413 The actual amount of total physical memory will either be 1414 auto detected or can be forced by using a kernel command line option 1415 such as "mem=256M". (Try "man bootparam" or see the documentation of 1416 your boot loader (lilo or loadlin) about how to pass options to the 1417 kernel at boot time.) 1418 1419 If unsure, say "off". 1420 1421config HIGHMEM4G 1422 bool "4GB" 1423 help 1424 Select this if you have a 32-bit processor and between 1 and 4 1425 gigabytes of physical RAM. 1426 1427config HIGHMEM64G 1428 bool "64GB" 1429 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1430 select X86_PAE 1431 help 1432 Select this if you have a 32-bit processor and more than 4 1433 gigabytes of physical RAM. 1434 1435endchoice 1436 1437choice 1438 prompt "Memory split" if EXPERT 1439 default VMSPLIT_3G 1440 depends on X86_32 1441 help 1442 Select the desired split between kernel and user memory. 1443 1444 If the address range available to the kernel is less than the 1445 physical memory installed, the remaining memory will be available 1446 as "high memory". Accessing high memory is a little more costly 1447 than low memory, as it needs to be mapped into the kernel first. 1448 Note that increasing the kernel address space limits the range 1449 available to user programs, making the address space there 1450 tighter. Selecting anything other than the default 3G/1G split 1451 will also likely make your kernel incompatible with binary-only 1452 kernel modules. 1453 1454 If you are not absolutely sure what you are doing, leave this 1455 option alone! 1456 1457 config VMSPLIT_3G 1458 bool "3G/1G user/kernel split" 1459 config VMSPLIT_3G_OPT 1460 depends on !X86_PAE 1461 bool "3G/1G user/kernel split (for full 1G low memory)" 1462 config VMSPLIT_2G 1463 bool "2G/2G user/kernel split" 1464 config VMSPLIT_2G_OPT 1465 depends on !X86_PAE 1466 bool "2G/2G user/kernel split (for full 2G low memory)" 1467 config VMSPLIT_1G 1468 bool "1G/3G user/kernel split" 1469endchoice 1470 1471config PAGE_OFFSET 1472 hex 1473 default 0xB0000000 if VMSPLIT_3G_OPT 1474 default 0x80000000 if VMSPLIT_2G 1475 default 0x78000000 if VMSPLIT_2G_OPT 1476 default 0x40000000 if VMSPLIT_1G 1477 default 0xC0000000 1478 depends on X86_32 1479 1480config HIGHMEM 1481 def_bool y 1482 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1483 1484config X86_PAE 1485 bool "PAE (Physical Address Extension) Support" 1486 depends on X86_32 && !HIGHMEM4G 1487 select PHYS_ADDR_T_64BIT 1488 select SWIOTLB 1489 help 1490 PAE is required for NX support, and furthermore enables 1491 larger swapspace support for non-overcommit purposes. It 1492 has the cost of more pagetable lookup overhead, and also 1493 consumes more pagetable space per process. 1494 1495config X86_5LEVEL 1496 bool "Enable 5-level page tables support" 1497 default y 1498 select DYNAMIC_MEMORY_LAYOUT 1499 select SPARSEMEM_VMEMMAP 1500 depends on X86_64 1501 help 1502 5-level paging enables access to larger address space: 1503 upto 128 PiB of virtual address space and 4 PiB of 1504 physical address space. 1505 1506 It will be supported by future Intel CPUs. 1507 1508 A kernel with the option enabled can be booted on machines that 1509 support 4- or 5-level paging. 1510 1511 See Documentation/x86/x86_64/5level-paging.rst for more 1512 information. 1513 1514 Say N if unsure. 1515 1516config X86_DIRECT_GBPAGES 1517 def_bool y 1518 depends on X86_64 1519 help 1520 Certain kernel features effectively disable kernel 1521 linear 1 GB mappings (even if the CPU otherwise 1522 supports them), so don't confuse the user by printing 1523 that we have them enabled. 1524 1525config X86_CPA_STATISTICS 1526 bool "Enable statistic for Change Page Attribute" 1527 depends on DEBUG_FS 1528 help 1529 Expose statistics about the Change Page Attribute mechanism, which 1530 helps to determine the effectiveness of preserving large and huge 1531 page mappings when mapping protections are changed. 1532 1533config X86_MEM_ENCRYPT 1534 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1535 select DYNAMIC_PHYSICAL_MASK 1536 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS 1537 def_bool n 1538 1539config AMD_MEM_ENCRYPT 1540 bool "AMD Secure Memory Encryption (SME) support" 1541 depends on X86_64 && CPU_SUP_AMD 1542 select DMA_COHERENT_POOL 1543 select ARCH_USE_MEMREMAP_PROT 1544 select INSTRUCTION_DECODER 1545 select ARCH_HAS_CC_PLATFORM 1546 select X86_MEM_ENCRYPT 1547 help 1548 Say yes to enable support for the encryption of system memory. 1549 This requires an AMD processor that supports Secure Memory 1550 Encryption (SME). 1551 1552config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1553 bool "Activate AMD Secure Memory Encryption (SME) by default" 1554 depends on AMD_MEM_ENCRYPT 1555 help 1556 Say yes to have system memory encrypted by default if running on 1557 an AMD processor that supports Secure Memory Encryption (SME). 1558 1559 If set to Y, then the encryption of system memory can be 1560 deactivated with the mem_encrypt=off command line option. 1561 1562 If set to N, then the encryption of system memory can be 1563 activated with the mem_encrypt=on command line option. 1564 1565# Common NUMA Features 1566config NUMA 1567 bool "NUMA Memory Allocation and Scheduler Support" 1568 depends on SMP 1569 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1570 default y if X86_BIGSMP 1571 select USE_PERCPU_NUMA_NODE_ID 1572 help 1573 Enable NUMA (Non-Uniform Memory Access) support. 1574 1575 The kernel will try to allocate memory used by a CPU on the 1576 local memory controller of the CPU and add some more 1577 NUMA awareness to the kernel. 1578 1579 For 64-bit this is recommended if the system is Intel Core i7 1580 (or later), AMD Opteron, or EM64T NUMA. 1581 1582 For 32-bit this is only needed if you boot a 32-bit 1583 kernel on a 64-bit NUMA platform. 1584 1585 Otherwise, you should say N. 1586 1587config AMD_NUMA 1588 def_bool y 1589 prompt "Old style AMD Opteron NUMA detection" 1590 depends on X86_64 && NUMA && PCI 1591 help 1592 Enable AMD NUMA node topology detection. You should say Y here if 1593 you have a multi processor AMD system. This uses an old method to 1594 read the NUMA configuration directly from the builtin Northbridge 1595 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1596 which also takes priority if both are compiled in. 1597 1598config X86_64_ACPI_NUMA 1599 def_bool y 1600 prompt "ACPI NUMA detection" 1601 depends on X86_64 && NUMA && ACPI && PCI 1602 select ACPI_NUMA 1603 help 1604 Enable ACPI SRAT based node topology detection. 1605 1606config NUMA_EMU 1607 bool "NUMA emulation" 1608 depends on NUMA 1609 help 1610 Enable NUMA emulation. A flat machine will be split 1611 into virtual nodes when booted with "numa=fake=N", where N is the 1612 number of nodes. This is only useful for debugging. 1613 1614config NODES_SHIFT 1615 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1616 range 1 10 1617 default "10" if MAXSMP 1618 default "6" if X86_64 1619 default "3" 1620 depends on NUMA 1621 help 1622 Specify the maximum number of NUMA Nodes available on the target 1623 system. Increases memory reserved to accommodate various tables. 1624 1625config ARCH_FLATMEM_ENABLE 1626 def_bool y 1627 depends on X86_32 && !NUMA 1628 1629config ARCH_SPARSEMEM_ENABLE 1630 def_bool y 1631 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1632 select SPARSEMEM_STATIC if X86_32 1633 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1634 1635config ARCH_SPARSEMEM_DEFAULT 1636 def_bool X86_64 || (NUMA && X86_32) 1637 1638config ARCH_SELECT_MEMORY_MODEL 1639 def_bool y 1640 depends on ARCH_SPARSEMEM_ENABLE 1641 1642config ARCH_MEMORY_PROBE 1643 bool "Enable sysfs memory/probe interface" 1644 depends on MEMORY_HOTPLUG 1645 help 1646 This option enables a sysfs memory/probe interface for testing. 1647 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1648 If you are unsure how to answer this question, answer N. 1649 1650config ARCH_PROC_KCORE_TEXT 1651 def_bool y 1652 depends on X86_64 && PROC_KCORE 1653 1654config ILLEGAL_POINTER_VALUE 1655 hex 1656 default 0 if X86_32 1657 default 0xdead000000000000 if X86_64 1658 1659config X86_PMEM_LEGACY_DEVICE 1660 bool 1661 1662config X86_PMEM_LEGACY 1663 tristate "Support non-standard NVDIMMs and ADR protected memory" 1664 depends on PHYS_ADDR_T_64BIT 1665 depends on BLK_DEV 1666 select X86_PMEM_LEGACY_DEVICE 1667 select NUMA_KEEP_MEMINFO if NUMA 1668 select LIBNVDIMM 1669 help 1670 Treat memory marked using the non-standard e820 type of 12 as used 1671 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1672 The kernel will offer these regions to the 'pmem' driver so 1673 they can be used for persistent storage. 1674 1675 Say Y if unsure. 1676 1677config HIGHPTE 1678 bool "Allocate 3rd-level pagetables from highmem" 1679 depends on HIGHMEM 1680 help 1681 The VM uses one page table entry for each page of physical memory. 1682 For systems with a lot of RAM, this can be wasteful of precious 1683 low memory. Setting this option will put user-space page table 1684 entries in high memory. 1685 1686config X86_CHECK_BIOS_CORRUPTION 1687 bool "Check for low memory corruption" 1688 help 1689 Periodically check for memory corruption in low memory, which 1690 is suspected to be caused by BIOS. Even when enabled in the 1691 configuration, it is disabled at runtime. Enable it by 1692 setting "memory_corruption_check=1" on the kernel command 1693 line. By default it scans the low 64k of memory every 60 1694 seconds; see the memory_corruption_check_size and 1695 memory_corruption_check_period parameters in 1696 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1697 1698 When enabled with the default parameters, this option has 1699 almost no overhead, as it reserves a relatively small amount 1700 of memory and scans it infrequently. It both detects corruption 1701 and prevents it from affecting the running system. 1702 1703 It is, however, intended as a diagnostic tool; if repeatable 1704 BIOS-originated corruption always affects the same memory, 1705 you can use memmap= to prevent the kernel from using that 1706 memory. 1707 1708config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1709 bool "Set the default setting of memory_corruption_check" 1710 depends on X86_CHECK_BIOS_CORRUPTION 1711 default y 1712 help 1713 Set whether the default state of memory_corruption_check is 1714 on or off. 1715 1716config MATH_EMULATION 1717 bool 1718 depends on MODIFY_LDT_SYSCALL 1719 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1720 help 1721 Linux can emulate a math coprocessor (used for floating point 1722 operations) if you don't have one. 486DX and Pentium processors have 1723 a math coprocessor built in, 486SX and 386 do not, unless you added 1724 a 487DX or 387, respectively. (The messages during boot time can 1725 give you some hints here ["man dmesg"].) Everyone needs either a 1726 coprocessor or this emulation. 1727 1728 If you don't have a math coprocessor, you need to say Y here; if you 1729 say Y here even though you have a coprocessor, the coprocessor will 1730 be used nevertheless. (This behavior can be changed with the kernel 1731 command line option "no387", which comes handy if your coprocessor 1732 is broken. Try "man bootparam" or see the documentation of your boot 1733 loader (lilo or loadlin) about how to pass options to the kernel at 1734 boot time.) This means that it is a good idea to say Y here if you 1735 intend to use this kernel on different machines. 1736 1737 More information about the internals of the Linux math coprocessor 1738 emulation can be found in <file:arch/x86/math-emu/README>. 1739 1740 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1741 kernel, it won't hurt. 1742 1743config MTRR 1744 def_bool y 1745 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1746 help 1747 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1748 the Memory Type Range Registers (MTRRs) may be used to control 1749 processor access to memory ranges. This is most useful if you have 1750 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1751 allows bus write transfers to be combined into a larger transfer 1752 before bursting over the PCI/AGP bus. This can increase performance 1753 of image write operations 2.5 times or more. Saying Y here creates a 1754 /proc/mtrr file which may be used to manipulate your processor's 1755 MTRRs. Typically the X server should use this. 1756 1757 This code has a reasonably generic interface so that similar 1758 control registers on other processors can be easily supported 1759 as well: 1760 1761 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1762 Registers (ARRs) which provide a similar functionality to MTRRs. For 1763 these, the ARRs are used to emulate the MTRRs. 1764 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1765 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1766 write-combining. All of these processors are supported by this code 1767 and it makes sense to say Y here if you have one of them. 1768 1769 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1770 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1771 can lead to all sorts of problems, so it's good to say Y here. 1772 1773 You can safely say Y even if your machine doesn't have MTRRs, you'll 1774 just add about 9 KB to your kernel. 1775 1776 See <file:Documentation/x86/mtrr.rst> for more information. 1777 1778config MTRR_SANITIZER 1779 def_bool y 1780 prompt "MTRR cleanup support" 1781 depends on MTRR 1782 help 1783 Convert MTRR layout from continuous to discrete, so X drivers can 1784 add writeback entries. 1785 1786 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1787 The largest mtrr entry size for a continuous block can be set with 1788 mtrr_chunk_size. 1789 1790 If unsure, say Y. 1791 1792config MTRR_SANITIZER_ENABLE_DEFAULT 1793 int "MTRR cleanup enable value (0-1)" 1794 range 0 1 1795 default "0" 1796 depends on MTRR_SANITIZER 1797 help 1798 Enable mtrr cleanup default value 1799 1800config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1801 int "MTRR cleanup spare reg num (0-7)" 1802 range 0 7 1803 default "1" 1804 depends on MTRR_SANITIZER 1805 help 1806 mtrr cleanup spare entries default, it can be changed via 1807 mtrr_spare_reg_nr=N on the kernel command line. 1808 1809config X86_PAT 1810 def_bool y 1811 prompt "x86 PAT support" if EXPERT 1812 depends on MTRR 1813 help 1814 Use PAT attributes to setup page level cache control. 1815 1816 PATs are the modern equivalents of MTRRs and are much more 1817 flexible than MTRRs. 1818 1819 Say N here if you see bootup problems (boot crash, boot hang, 1820 spontaneous reboots) or a non-working video driver. 1821 1822 If unsure, say Y. 1823 1824config ARCH_USES_PG_UNCACHED 1825 def_bool y 1826 depends on X86_PAT 1827 1828config ARCH_RANDOM 1829 def_bool y 1830 prompt "x86 architectural random number generator" if EXPERT 1831 help 1832 Enable the x86 architectural RDRAND instruction 1833 (Intel Bull Mountain technology) to generate random numbers. 1834 If supported, this is a high bandwidth, cryptographically 1835 secure hardware random number generator. 1836 1837config X86_SMAP 1838 def_bool y 1839 prompt "Supervisor Mode Access Prevention" if EXPERT 1840 help 1841 Supervisor Mode Access Prevention (SMAP) is a security 1842 feature in newer Intel processors. There is a small 1843 performance cost if this enabled and turned on; there is 1844 also a small increase in the kernel size if this is enabled. 1845 1846 If unsure, say Y. 1847 1848config X86_UMIP 1849 def_bool y 1850 prompt "User Mode Instruction Prevention" if EXPERT 1851 help 1852 User Mode Instruction Prevention (UMIP) is a security feature in 1853 some x86 processors. If enabled, a general protection fault is 1854 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1855 executed in user mode. These instructions unnecessarily expose 1856 information about the hardware state. 1857 1858 The vast majority of applications do not use these instructions. 1859 For the very few that do, software emulation is provided in 1860 specific cases in protected and virtual-8086 modes. Emulated 1861 results are dummy. 1862 1863config X86_INTEL_MEMORY_PROTECTION_KEYS 1864 prompt "Memory Protection Keys" 1865 def_bool y 1866 # Note: only available in 64-bit mode 1867 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1868 select ARCH_USES_HIGH_VMA_FLAGS 1869 select ARCH_HAS_PKEYS 1870 help 1871 Memory Protection Keys provides a mechanism for enforcing 1872 page-based protections, but without requiring modification of the 1873 page tables when an application changes protection domains. 1874 1875 For details, see Documentation/core-api/protection-keys.rst 1876 1877 If unsure, say y. 1878 1879choice 1880 prompt "TSX enable mode" 1881 depends on CPU_SUP_INTEL 1882 default X86_INTEL_TSX_MODE_OFF 1883 help 1884 Intel's TSX (Transactional Synchronization Extensions) feature 1885 allows to optimize locking protocols through lock elision which 1886 can lead to a noticeable performance boost. 1887 1888 On the other hand it has been shown that TSX can be exploited 1889 to form side channel attacks (e.g. TAA) and chances are there 1890 will be more of those attacks discovered in the future. 1891 1892 Therefore TSX is not enabled by default (aka tsx=off). An admin 1893 might override this decision by tsx=on the command line parameter. 1894 Even with TSX enabled, the kernel will attempt to enable the best 1895 possible TAA mitigation setting depending on the microcode available 1896 for the particular machine. 1897 1898 This option allows to set the default tsx mode between tsx=on, =off 1899 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1900 details. 1901 1902 Say off if not sure, auto if TSX is in use but it should be used on safe 1903 platforms or on if TSX is in use and the security aspect of tsx is not 1904 relevant. 1905 1906config X86_INTEL_TSX_MODE_OFF 1907 bool "off" 1908 help 1909 TSX is disabled if possible - equals to tsx=off command line parameter. 1910 1911config X86_INTEL_TSX_MODE_ON 1912 bool "on" 1913 help 1914 TSX is always enabled on TSX capable HW - equals the tsx=on command 1915 line parameter. 1916 1917config X86_INTEL_TSX_MODE_AUTO 1918 bool "auto" 1919 help 1920 TSX is enabled on TSX capable HW that is believed to be safe against 1921 side channel attacks- equals the tsx=auto command line parameter. 1922endchoice 1923 1924config X86_SGX 1925 bool "Software Guard eXtensions (SGX)" 1926 depends on X86_64 && CPU_SUP_INTEL 1927 depends on CRYPTO=y 1928 depends on CRYPTO_SHA256=y 1929 select SRCU 1930 select MMU_NOTIFIER 1931 select NUMA_KEEP_MEMINFO if NUMA 1932 select XARRAY_MULTI 1933 help 1934 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1935 that can be used by applications to set aside private regions of code 1936 and data, referred to as enclaves. An enclave's private memory can 1937 only be accessed by code running within the enclave. Accesses from 1938 outside the enclave, including other enclaves, are disallowed by 1939 hardware. 1940 1941 If unsure, say N. 1942 1943config EFI 1944 bool "EFI runtime service support" 1945 depends on ACPI 1946 select UCS2_STRING 1947 select EFI_RUNTIME_WRAPPERS 1948 select ARCH_USE_MEMREMAP_PROT 1949 help 1950 This enables the kernel to use EFI runtime services that are 1951 available (such as the EFI variable services). 1952 1953 This option is only useful on systems that have EFI firmware. 1954 In addition, you should use the latest ELILO loader available 1955 at <http://elilo.sourceforge.net> in order to take advantage 1956 of EFI runtime services. However, even with this option, the 1957 resultant kernel should continue to boot on existing non-EFI 1958 platforms. 1959 1960config EFI_STUB 1961 bool "EFI stub support" 1962 depends on EFI 1963 depends on $(cc-option,-mabi=ms) || X86_32 1964 select RELOCATABLE 1965 help 1966 This kernel feature allows a bzImage to be loaded directly 1967 by EFI firmware without the use of a bootloader. 1968 1969 See Documentation/admin-guide/efi-stub.rst for more information. 1970 1971config EFI_MIXED 1972 bool "EFI mixed-mode support" 1973 depends on EFI_STUB && X86_64 1974 help 1975 Enabling this feature allows a 64-bit kernel to be booted 1976 on a 32-bit firmware, provided that your CPU supports 64-bit 1977 mode. 1978 1979 Note that it is not possible to boot a mixed-mode enabled 1980 kernel via the EFI boot stub - a bootloader that supports 1981 the EFI handover protocol must be used. 1982 1983 If unsure, say N. 1984 1985source "kernel/Kconfig.hz" 1986 1987config KEXEC 1988 bool "kexec system call" 1989 select KEXEC_CORE 1990 help 1991 kexec is a system call that implements the ability to shutdown your 1992 current kernel, and to start another kernel. It is like a reboot 1993 but it is independent of the system firmware. And like a reboot 1994 you can start any kernel with it, not just Linux. 1995 1996 The name comes from the similarity to the exec system call. 1997 1998 It is an ongoing process to be certain the hardware in a machine 1999 is properly shutdown, so do not be surprised if this code does not 2000 initially work for you. As of this writing the exact hardware 2001 interface is strongly in flux, so no good recommendation can be 2002 made. 2003 2004config KEXEC_FILE 2005 bool "kexec file based system call" 2006 select KEXEC_CORE 2007 select BUILD_BIN2C 2008 depends on X86_64 2009 depends on CRYPTO=y 2010 depends on CRYPTO_SHA256=y 2011 help 2012 This is new version of kexec system call. This system call is 2013 file based and takes file descriptors as system call argument 2014 for kernel and initramfs as opposed to list of segments as 2015 accepted by previous system call. 2016 2017config ARCH_HAS_KEXEC_PURGATORY 2018 def_bool KEXEC_FILE 2019 2020config KEXEC_SIG 2021 bool "Verify kernel signature during kexec_file_load() syscall" 2022 depends on KEXEC_FILE 2023 help 2024 2025 This option makes the kexec_file_load() syscall check for a valid 2026 signature of the kernel image. The image can still be loaded without 2027 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2028 there's a signature that we can check, then it must be valid. 2029 2030 In addition to this option, you need to enable signature 2031 verification for the corresponding kernel image type being 2032 loaded in order for this to work. 2033 2034config KEXEC_SIG_FORCE 2035 bool "Require a valid signature in kexec_file_load() syscall" 2036 depends on KEXEC_SIG 2037 help 2038 This option makes kernel signature verification mandatory for 2039 the kexec_file_load() syscall. 2040 2041config KEXEC_BZIMAGE_VERIFY_SIG 2042 bool "Enable bzImage signature verification support" 2043 depends on KEXEC_SIG 2044 depends on SIGNED_PE_FILE_VERIFICATION 2045 select SYSTEM_TRUSTED_KEYRING 2046 help 2047 Enable bzImage signature verification support. 2048 2049config CRASH_DUMP 2050 bool "kernel crash dumps" 2051 depends on X86_64 || (X86_32 && HIGHMEM) 2052 help 2053 Generate crash dump after being started by kexec. 2054 This should be normally only set in special crash dump kernels 2055 which are loaded in the main kernel with kexec-tools into 2056 a specially reserved region and then later executed after 2057 a crash by kdump/kexec. The crash dump kernel must be compiled 2058 to a memory address not used by the main kernel or BIOS using 2059 PHYSICAL_START, or it must be built as a relocatable image 2060 (CONFIG_RELOCATABLE=y). 2061 For more details see Documentation/admin-guide/kdump/kdump.rst 2062 2063config KEXEC_JUMP 2064 bool "kexec jump" 2065 depends on KEXEC && HIBERNATION 2066 help 2067 Jump between original kernel and kexeced kernel and invoke 2068 code in physical address mode via KEXEC 2069 2070config PHYSICAL_START 2071 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2072 default "0x1000000" 2073 help 2074 This gives the physical address where the kernel is loaded. 2075 2076 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2077 bzImage will decompress itself to above physical address and 2078 run from there. Otherwise, bzImage will run from the address where 2079 it has been loaded by the boot loader and will ignore above physical 2080 address. 2081 2082 In normal kdump cases one does not have to set/change this option 2083 as now bzImage can be compiled as a completely relocatable image 2084 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2085 address. This option is mainly useful for the folks who don't want 2086 to use a bzImage for capturing the crash dump and want to use a 2087 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2088 to be specifically compiled to run from a specific memory area 2089 (normally a reserved region) and this option comes handy. 2090 2091 So if you are using bzImage for capturing the crash dump, 2092 leave the value here unchanged to 0x1000000 and set 2093 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2094 for capturing the crash dump change this value to start of 2095 the reserved region. In other words, it can be set based on 2096 the "X" value as specified in the "crashkernel=YM@XM" 2097 command line boot parameter passed to the panic-ed 2098 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2099 for more details about crash dumps. 2100 2101 Usage of bzImage for capturing the crash dump is recommended as 2102 one does not have to build two kernels. Same kernel can be used 2103 as production kernel and capture kernel. Above option should have 2104 gone away after relocatable bzImage support is introduced. But it 2105 is present because there are users out there who continue to use 2106 vmlinux for dump capture. This option should go away down the 2107 line. 2108 2109 Don't change this unless you know what you are doing. 2110 2111config RELOCATABLE 2112 bool "Build a relocatable kernel" 2113 default y 2114 help 2115 This builds a kernel image that retains relocation information 2116 so it can be loaded someplace besides the default 1MB. 2117 The relocations tend to make the kernel binary about 10% larger, 2118 but are discarded at runtime. 2119 2120 One use is for the kexec on panic case where the recovery kernel 2121 must live at a different physical address than the primary 2122 kernel. 2123 2124 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2125 it has been loaded at and the compile time physical address 2126 (CONFIG_PHYSICAL_START) is used as the minimum location. 2127 2128config RANDOMIZE_BASE 2129 bool "Randomize the address of the kernel image (KASLR)" 2130 depends on RELOCATABLE 2131 default y 2132 help 2133 In support of Kernel Address Space Layout Randomization (KASLR), 2134 this randomizes the physical address at which the kernel image 2135 is decompressed and the virtual address where the kernel 2136 image is mapped, as a security feature that deters exploit 2137 attempts relying on knowledge of the location of kernel 2138 code internals. 2139 2140 On 64-bit, the kernel physical and virtual addresses are 2141 randomized separately. The physical address will be anywhere 2142 between 16MB and the top of physical memory (up to 64TB). The 2143 virtual address will be randomized from 16MB up to 1GB (9 bits 2144 of entropy). Note that this also reduces the memory space 2145 available to kernel modules from 1.5GB to 1GB. 2146 2147 On 32-bit, the kernel physical and virtual addresses are 2148 randomized together. They will be randomized from 16MB up to 2149 512MB (8 bits of entropy). 2150 2151 Entropy is generated using the RDRAND instruction if it is 2152 supported. If RDTSC is supported, its value is mixed into 2153 the entropy pool as well. If neither RDRAND nor RDTSC are 2154 supported, then entropy is read from the i8254 timer. The 2155 usable entropy is limited by the kernel being built using 2156 2GB addressing, and that PHYSICAL_ALIGN must be at a 2157 minimum of 2MB. As a result, only 10 bits of entropy are 2158 theoretically possible, but the implementations are further 2159 limited due to memory layouts. 2160 2161 If unsure, say Y. 2162 2163# Relocation on x86 needs some additional build support 2164config X86_NEED_RELOCS 2165 def_bool y 2166 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2167 2168config PHYSICAL_ALIGN 2169 hex "Alignment value to which kernel should be aligned" 2170 default "0x200000" 2171 range 0x2000 0x1000000 if X86_32 2172 range 0x200000 0x1000000 if X86_64 2173 help 2174 This value puts the alignment restrictions on physical address 2175 where kernel is loaded and run from. Kernel is compiled for an 2176 address which meets above alignment restriction. 2177 2178 If bootloader loads the kernel at a non-aligned address and 2179 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2180 address aligned to above value and run from there. 2181 2182 If bootloader loads the kernel at a non-aligned address and 2183 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2184 load address and decompress itself to the address it has been 2185 compiled for and run from there. The address for which kernel is 2186 compiled already meets above alignment restrictions. Hence the 2187 end result is that kernel runs from a physical address meeting 2188 above alignment restrictions. 2189 2190 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2191 this value must be a multiple of 0x200000. 2192 2193 Don't change this unless you know what you are doing. 2194 2195config DYNAMIC_MEMORY_LAYOUT 2196 bool 2197 help 2198 This option makes base addresses of vmalloc and vmemmap as well as 2199 __PAGE_OFFSET movable during boot. 2200 2201config RANDOMIZE_MEMORY 2202 bool "Randomize the kernel memory sections" 2203 depends on X86_64 2204 depends on RANDOMIZE_BASE 2205 select DYNAMIC_MEMORY_LAYOUT 2206 default RANDOMIZE_BASE 2207 help 2208 Randomizes the base virtual address of kernel memory sections 2209 (physical memory mapping, vmalloc & vmemmap). This security feature 2210 makes exploits relying on predictable memory locations less reliable. 2211 2212 The order of allocations remains unchanged. Entropy is generated in 2213 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2214 configuration have in average 30,000 different possible virtual 2215 addresses for each memory section. 2216 2217 If unsure, say Y. 2218 2219config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2220 hex "Physical memory mapping padding" if EXPERT 2221 depends on RANDOMIZE_MEMORY 2222 default "0xa" if MEMORY_HOTPLUG 2223 default "0x0" 2224 range 0x1 0x40 if MEMORY_HOTPLUG 2225 range 0x0 0x40 2226 help 2227 Define the padding in terabytes added to the existing physical 2228 memory size during kernel memory randomization. It is useful 2229 for memory hotplug support but reduces the entropy available for 2230 address randomization. 2231 2232 If unsure, leave at the default value. 2233 2234config HOTPLUG_CPU 2235 def_bool y 2236 depends on SMP 2237 2238config BOOTPARAM_HOTPLUG_CPU0 2239 bool "Set default setting of cpu0_hotpluggable" 2240 depends on HOTPLUG_CPU 2241 help 2242 Set whether default state of cpu0_hotpluggable is on or off. 2243 2244 Say Y here to enable CPU0 hotplug by default. If this switch 2245 is turned on, there is no need to give cpu0_hotplug kernel 2246 parameter and the CPU0 hotplug feature is enabled by default. 2247 2248 Please note: there are two known CPU0 dependencies if you want 2249 to enable the CPU0 hotplug feature either by this switch or by 2250 cpu0_hotplug kernel parameter. 2251 2252 First, resume from hibernate or suspend always starts from CPU0. 2253 So hibernate and suspend are prevented if CPU0 is offline. 2254 2255 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2256 offline if any interrupt can not migrate out of CPU0. There may 2257 be other CPU0 dependencies. 2258 2259 Please make sure the dependencies are under your control before 2260 you enable this feature. 2261 2262 Say N if you don't want to enable CPU0 hotplug feature by default. 2263 You still can enable the CPU0 hotplug feature at boot by kernel 2264 parameter cpu0_hotplug. 2265 2266config DEBUG_HOTPLUG_CPU0 2267 def_bool n 2268 prompt "Debug CPU0 hotplug" 2269 depends on HOTPLUG_CPU 2270 help 2271 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2272 soon as possible and boots up userspace with CPU0 offlined. User 2273 can online CPU0 back after boot time. 2274 2275 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2276 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2277 compilation or giving cpu0_hotplug kernel parameter at boot. 2278 2279 If unsure, say N. 2280 2281config COMPAT_VDSO 2282 def_bool n 2283 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2284 depends on COMPAT_32 2285 help 2286 Certain buggy versions of glibc will crash if they are 2287 presented with a 32-bit vDSO that is not mapped at the address 2288 indicated in its segment table. 2289 2290 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2291 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2292 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2293 the only released version with the bug, but OpenSUSE 9 2294 contains a buggy "glibc 2.3.2". 2295 2296 The symptom of the bug is that everything crashes on startup, saying: 2297 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2298 2299 Saying Y here changes the default value of the vdso32 boot 2300 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2301 This works around the glibc bug but hurts performance. 2302 2303 If unsure, say N: if you are compiling your own kernel, you 2304 are unlikely to be using a buggy version of glibc. 2305 2306choice 2307 prompt "vsyscall table for legacy applications" 2308 depends on X86_64 2309 default LEGACY_VSYSCALL_XONLY 2310 help 2311 Legacy user code that does not know how to find the vDSO expects 2312 to be able to issue three syscalls by calling fixed addresses in 2313 kernel space. Since this location is not randomized with ASLR, 2314 it can be used to assist security vulnerability exploitation. 2315 2316 This setting can be changed at boot time via the kernel command 2317 line parameter vsyscall=[emulate|xonly|none]. 2318 2319 On a system with recent enough glibc (2.14 or newer) and no 2320 static binaries, you can say None without a performance penalty 2321 to improve security. 2322 2323 If unsure, select "Emulate execution only". 2324 2325 config LEGACY_VSYSCALL_EMULATE 2326 bool "Full emulation" 2327 help 2328 The kernel traps and emulates calls into the fixed vsyscall 2329 address mapping. This makes the mapping non-executable, but 2330 it still contains readable known contents, which could be 2331 used in certain rare security vulnerability exploits. This 2332 configuration is recommended when using legacy userspace 2333 that still uses vsyscalls along with legacy binary 2334 instrumentation tools that require code to be readable. 2335 2336 An example of this type of legacy userspace is running 2337 Pin on an old binary that still uses vsyscalls. 2338 2339 config LEGACY_VSYSCALL_XONLY 2340 bool "Emulate execution only" 2341 help 2342 The kernel traps and emulates calls into the fixed vsyscall 2343 address mapping and does not allow reads. This 2344 configuration is recommended when userspace might use the 2345 legacy vsyscall area but support for legacy binary 2346 instrumentation of legacy code is not needed. It mitigates 2347 certain uses of the vsyscall area as an ASLR-bypassing 2348 buffer. 2349 2350 config LEGACY_VSYSCALL_NONE 2351 bool "None" 2352 help 2353 There will be no vsyscall mapping at all. This will 2354 eliminate any risk of ASLR bypass due to the vsyscall 2355 fixed address mapping. Attempts to use the vsyscalls 2356 will be reported to dmesg, so that either old or 2357 malicious userspace programs can be identified. 2358 2359endchoice 2360 2361config CMDLINE_BOOL 2362 bool "Built-in kernel command line" 2363 help 2364 Allow for specifying boot arguments to the kernel at 2365 build time. On some systems (e.g. embedded ones), it is 2366 necessary or convenient to provide some or all of the 2367 kernel boot arguments with the kernel itself (that is, 2368 to not rely on the boot loader to provide them.) 2369 2370 To compile command line arguments into the kernel, 2371 set this option to 'Y', then fill in the 2372 boot arguments in CONFIG_CMDLINE. 2373 2374 Systems with fully functional boot loaders (i.e. non-embedded) 2375 should leave this option set to 'N'. 2376 2377config CMDLINE 2378 string "Built-in kernel command string" 2379 depends on CMDLINE_BOOL 2380 default "" 2381 help 2382 Enter arguments here that should be compiled into the kernel 2383 image and used at boot time. If the boot loader provides a 2384 command line at boot time, it is appended to this string to 2385 form the full kernel command line, when the system boots. 2386 2387 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2388 change this behavior. 2389 2390 In most cases, the command line (whether built-in or provided 2391 by the boot loader) should specify the device for the root 2392 file system. 2393 2394config CMDLINE_OVERRIDE 2395 bool "Built-in command line overrides boot loader arguments" 2396 depends on CMDLINE_BOOL && CMDLINE != "" 2397 help 2398 Set this option to 'Y' to have the kernel ignore the boot loader 2399 command line, and use ONLY the built-in command line. 2400 2401 This is used to work around broken boot loaders. This should 2402 be set to 'N' under normal conditions. 2403 2404config MODIFY_LDT_SYSCALL 2405 bool "Enable the LDT (local descriptor table)" if EXPERT 2406 default y 2407 help 2408 Linux can allow user programs to install a per-process x86 2409 Local Descriptor Table (LDT) using the modify_ldt(2) system 2410 call. This is required to run 16-bit or segmented code such as 2411 DOSEMU or some Wine programs. It is also used by some very old 2412 threading libraries. 2413 2414 Enabling this feature adds a small amount of overhead to 2415 context switches and increases the low-level kernel attack 2416 surface. Disabling it removes the modify_ldt(2) system call. 2417 2418 Saying 'N' here may make sense for embedded or server kernels. 2419 2420config STRICT_SIGALTSTACK_SIZE 2421 bool "Enforce strict size checking for sigaltstack" 2422 depends on DYNAMIC_SIGFRAME 2423 help 2424 For historical reasons MINSIGSTKSZ is a constant which became 2425 already too small with AVX512 support. Add a mechanism to 2426 enforce strict checking of the sigaltstack size against the 2427 real size of the FPU frame. This option enables the check 2428 by default. It can also be controlled via the kernel command 2429 line option 'strict_sas_size' independent of this config 2430 switch. Enabling it might break existing applications which 2431 allocate a too small sigaltstack but 'work' because they 2432 never get a signal delivered. 2433 2434 Say 'N' unless you want to really enforce this check. 2435 2436source "kernel/livepatch/Kconfig" 2437 2438endmenu 2439 2440config ARCH_HAS_ADD_PAGES 2441 def_bool y 2442 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2443 2444config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2445 def_bool y 2446 2447menu "Power management and ACPI options" 2448 2449config ARCH_HIBERNATION_HEADER 2450 def_bool y 2451 depends on HIBERNATION 2452 2453source "kernel/power/Kconfig" 2454 2455source "drivers/acpi/Kconfig" 2456 2457config X86_APM_BOOT 2458 def_bool y 2459 depends on APM 2460 2461menuconfig APM 2462 tristate "APM (Advanced Power Management) BIOS support" 2463 depends on X86_32 && PM_SLEEP 2464 help 2465 APM is a BIOS specification for saving power using several different 2466 techniques. This is mostly useful for battery powered laptops with 2467 APM compliant BIOSes. If you say Y here, the system time will be 2468 reset after a RESUME operation, the /proc/apm device will provide 2469 battery status information, and user-space programs will receive 2470 notification of APM "events" (e.g. battery status change). 2471 2472 If you select "Y" here, you can disable actual use of the APM 2473 BIOS by passing the "apm=off" option to the kernel at boot time. 2474 2475 Note that the APM support is almost completely disabled for 2476 machines with more than one CPU. 2477 2478 In order to use APM, you will need supporting software. For location 2479 and more information, read <file:Documentation/power/apm-acpi.rst> 2480 and the Battery Powered Linux mini-HOWTO, available from 2481 <http://www.tldp.org/docs.html#howto>. 2482 2483 This driver does not spin down disk drives (see the hdparm(8) 2484 manpage ("man 8 hdparm") for that), and it doesn't turn off 2485 VESA-compliant "green" monitors. 2486 2487 This driver does not support the TI 4000M TravelMate and the ACER 2488 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2489 desktop machines also don't have compliant BIOSes, and this driver 2490 may cause those machines to panic during the boot phase. 2491 2492 Generally, if you don't have a battery in your machine, there isn't 2493 much point in using this driver and you should say N. If you get 2494 random kernel OOPSes or reboots that don't seem to be related to 2495 anything, try disabling/enabling this option (or disabling/enabling 2496 APM in your BIOS). 2497 2498 Some other things you should try when experiencing seemingly random, 2499 "weird" problems: 2500 2501 1) make sure that you have enough swap space and that it is 2502 enabled. 2503 2) pass the "no-hlt" option to the kernel 2504 3) switch on floating point emulation in the kernel and pass 2505 the "no387" option to the kernel 2506 4) pass the "floppy=nodma" option to the kernel 2507 5) pass the "mem=4M" option to the kernel (thereby disabling 2508 all but the first 4 MB of RAM) 2509 6) make sure that the CPU is not over clocked. 2510 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2511 8) disable the cache from your BIOS settings 2512 9) install a fan for the video card or exchange video RAM 2513 10) install a better fan for the CPU 2514 11) exchange RAM chips 2515 12) exchange the motherboard. 2516 2517 To compile this driver as a module, choose M here: the 2518 module will be called apm. 2519 2520if APM 2521 2522config APM_IGNORE_USER_SUSPEND 2523 bool "Ignore USER SUSPEND" 2524 help 2525 This option will ignore USER SUSPEND requests. On machines with a 2526 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2527 series notebooks, it is necessary to say Y because of a BIOS bug. 2528 2529config APM_DO_ENABLE 2530 bool "Enable PM at boot time" 2531 help 2532 Enable APM features at boot time. From page 36 of the APM BIOS 2533 specification: "When disabled, the APM BIOS does not automatically 2534 power manage devices, enter the Standby State, enter the Suspend 2535 State, or take power saving steps in response to CPU Idle calls." 2536 This driver will make CPU Idle calls when Linux is idle (unless this 2537 feature is turned off -- see "Do CPU IDLE calls", below). This 2538 should always save battery power, but more complicated APM features 2539 will be dependent on your BIOS implementation. You may need to turn 2540 this option off if your computer hangs at boot time when using APM 2541 support, or if it beeps continuously instead of suspending. Turn 2542 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2543 T400CDT. This is off by default since most machines do fine without 2544 this feature. 2545 2546config APM_CPU_IDLE 2547 depends on CPU_IDLE 2548 bool "Make CPU Idle calls when idle" 2549 help 2550 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2551 On some machines, this can activate improved power savings, such as 2552 a slowed CPU clock rate, when the machine is idle. These idle calls 2553 are made after the idle loop has run for some length of time (e.g., 2554 333 mS). On some machines, this will cause a hang at boot time or 2555 whenever the CPU becomes idle. (On machines with more than one CPU, 2556 this option does nothing.) 2557 2558config APM_DISPLAY_BLANK 2559 bool "Enable console blanking using APM" 2560 help 2561 Enable console blanking using the APM. Some laptops can use this to 2562 turn off the LCD backlight when the screen blanker of the Linux 2563 virtual console blanks the screen. Note that this is only used by 2564 the virtual console screen blanker, and won't turn off the backlight 2565 when using the X Window system. This also doesn't have anything to 2566 do with your VESA-compliant power-saving monitor. Further, this 2567 option doesn't work for all laptops -- it might not turn off your 2568 backlight at all, or it might print a lot of errors to the console, 2569 especially if you are using gpm. 2570 2571config APM_ALLOW_INTS 2572 bool "Allow interrupts during APM BIOS calls" 2573 help 2574 Normally we disable external interrupts while we are making calls to 2575 the APM BIOS as a measure to lessen the effects of a badly behaving 2576 BIOS implementation. The BIOS should reenable interrupts if it 2577 needs to. Unfortunately, some BIOSes do not -- especially those in 2578 many of the newer IBM Thinkpads. If you experience hangs when you 2579 suspend, try setting this to Y. Otherwise, say N. 2580 2581endif # APM 2582 2583source "drivers/cpufreq/Kconfig" 2584 2585source "drivers/cpuidle/Kconfig" 2586 2587source "drivers/idle/Kconfig" 2588 2589endmenu 2590 2591 2592menu "Bus options (PCI etc.)" 2593 2594choice 2595 prompt "PCI access mode" 2596 depends on X86_32 && PCI 2597 default PCI_GOANY 2598 help 2599 On PCI systems, the BIOS can be used to detect the PCI devices and 2600 determine their configuration. However, some old PCI motherboards 2601 have BIOS bugs and may crash if this is done. Also, some embedded 2602 PCI-based systems don't have any BIOS at all. Linux can also try to 2603 detect the PCI hardware directly without using the BIOS. 2604 2605 With this option, you can specify how Linux should detect the 2606 PCI devices. If you choose "BIOS", the BIOS will be used, 2607 if you choose "Direct", the BIOS won't be used, and if you 2608 choose "MMConfig", then PCI Express MMCONFIG will be used. 2609 If you choose "Any", the kernel will try MMCONFIG, then the 2610 direct access method and falls back to the BIOS if that doesn't 2611 work. If unsure, go with the default, which is "Any". 2612 2613config PCI_GOBIOS 2614 bool "BIOS" 2615 2616config PCI_GOMMCONFIG 2617 bool "MMConfig" 2618 2619config PCI_GODIRECT 2620 bool "Direct" 2621 2622config PCI_GOOLPC 2623 bool "OLPC XO-1" 2624 depends on OLPC 2625 2626config PCI_GOANY 2627 bool "Any" 2628 2629endchoice 2630 2631config PCI_BIOS 2632 def_bool y 2633 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2634 2635# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2636config PCI_DIRECT 2637 def_bool y 2638 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2639 2640config PCI_MMCONFIG 2641 bool "Support mmconfig PCI config space access" if X86_64 2642 default y 2643 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2644 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2645 2646config PCI_OLPC 2647 def_bool y 2648 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2649 2650config PCI_XEN 2651 def_bool y 2652 depends on PCI && XEN 2653 2654config MMCONF_FAM10H 2655 def_bool y 2656 depends on X86_64 && PCI_MMCONFIG && ACPI 2657 2658config PCI_CNB20LE_QUIRK 2659 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2660 depends on PCI 2661 help 2662 Read the PCI windows out of the CNB20LE host bridge. This allows 2663 PCI hotplug to work on systems with the CNB20LE chipset which do 2664 not have ACPI. 2665 2666 There's no public spec for this chipset, and this functionality 2667 is known to be incomplete. 2668 2669 You should say N unless you know you need this. 2670 2671config ISA_BUS 2672 bool "ISA bus support on modern systems" if EXPERT 2673 help 2674 Expose ISA bus device drivers and options available for selection and 2675 configuration. Enable this option if your target machine has an ISA 2676 bus. ISA is an older system, displaced by PCI and newer bus 2677 architectures -- if your target machine is modern, it probably does 2678 not have an ISA bus. 2679 2680 If unsure, say N. 2681 2682# x86_64 have no ISA slots, but can have ISA-style DMA. 2683config ISA_DMA_API 2684 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2685 default y 2686 help 2687 Enables ISA-style DMA support for devices requiring such controllers. 2688 If unsure, say Y. 2689 2690if X86_32 2691 2692config ISA 2693 bool "ISA support" 2694 help 2695 Find out whether you have ISA slots on your motherboard. ISA is the 2696 name of a bus system, i.e. the way the CPU talks to the other stuff 2697 inside your box. Other bus systems are PCI, EISA, MicroChannel 2698 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2699 newer boards don't support it. If you have ISA, say Y, otherwise N. 2700 2701config SCx200 2702 tristate "NatSemi SCx200 support" 2703 help 2704 This provides basic support for National Semiconductor's 2705 (now AMD's) Geode processors. The driver probes for the 2706 PCI-IDs of several on-chip devices, so its a good dependency 2707 for other scx200_* drivers. 2708 2709 If compiled as a module, the driver is named scx200. 2710 2711config SCx200HR_TIMER 2712 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2713 depends on SCx200 2714 default y 2715 help 2716 This driver provides a clocksource built upon the on-chip 2717 27MHz high-resolution timer. Its also a workaround for 2718 NSC Geode SC-1100's buggy TSC, which loses time when the 2719 processor goes idle (as is done by the scheduler). The 2720 other workaround is idle=poll boot option. 2721 2722config OLPC 2723 bool "One Laptop Per Child support" 2724 depends on !X86_PAE 2725 select GPIOLIB 2726 select OF 2727 select OF_PROMTREE 2728 select IRQ_DOMAIN 2729 select OLPC_EC 2730 help 2731 Add support for detecting the unique features of the OLPC 2732 XO hardware. 2733 2734config OLPC_XO1_PM 2735 bool "OLPC XO-1 Power Management" 2736 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2737 help 2738 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2739 2740config OLPC_XO1_RTC 2741 bool "OLPC XO-1 Real Time Clock" 2742 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2743 help 2744 Add support for the XO-1 real time clock, which can be used as a 2745 programmable wakeup source. 2746 2747config OLPC_XO1_SCI 2748 bool "OLPC XO-1 SCI extras" 2749 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2750 depends on INPUT=y 2751 select POWER_SUPPLY 2752 help 2753 Add support for SCI-based features of the OLPC XO-1 laptop: 2754 - EC-driven system wakeups 2755 - Power button 2756 - Ebook switch 2757 - Lid switch 2758 - AC adapter status updates 2759 - Battery status updates 2760 2761config OLPC_XO15_SCI 2762 bool "OLPC XO-1.5 SCI extras" 2763 depends on OLPC && ACPI 2764 select POWER_SUPPLY 2765 help 2766 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2767 - EC-driven system wakeups 2768 - AC adapter status updates 2769 - Battery status updates 2770 2771config ALIX 2772 bool "PCEngines ALIX System Support (LED setup)" 2773 select GPIOLIB 2774 help 2775 This option enables system support for the PCEngines ALIX. 2776 At present this just sets up LEDs for GPIO control on 2777 ALIX2/3/6 boards. However, other system specific setup should 2778 get added here. 2779 2780 Note: You must still enable the drivers for GPIO and LED support 2781 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2782 2783 Note: You have to set alix.force=1 for boards with Award BIOS. 2784 2785config NET5501 2786 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2787 select GPIOLIB 2788 help 2789 This option enables system support for the Soekris Engineering net5501. 2790 2791config GEOS 2792 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2793 select GPIOLIB 2794 depends on DMI 2795 help 2796 This option enables system support for the Traverse Technologies GEOS. 2797 2798config TS5500 2799 bool "Technologic Systems TS-5500 platform support" 2800 depends on MELAN 2801 select CHECK_SIGNATURE 2802 select NEW_LEDS 2803 select LEDS_CLASS 2804 help 2805 This option enables system support for the Technologic Systems TS-5500. 2806 2807endif # X86_32 2808 2809config AMD_NB 2810 def_bool y 2811 depends on CPU_SUP_AMD && PCI 2812 2813endmenu 2814 2815 2816menu "Binary Emulations" 2817 2818config IA32_EMULATION 2819 bool "IA32 Emulation" 2820 depends on X86_64 2821 select ARCH_WANT_OLD_COMPAT_IPC 2822 select BINFMT_ELF 2823 select COMPAT_OLD_SIGACTION 2824 help 2825 Include code to run legacy 32-bit programs under a 2826 64-bit kernel. You should likely turn this on, unless you're 2827 100% sure that you don't have any 32-bit programs left. 2828 2829config IA32_AOUT 2830 tristate "IA32 a.out support" 2831 depends on IA32_EMULATION 2832 depends on BROKEN 2833 help 2834 Support old a.out binaries in the 32bit emulation. 2835 2836config X86_X32 2837 bool "x32 ABI for 64-bit mode" 2838 depends on X86_64 2839 help 2840 Include code to run binaries for the x32 native 32-bit ABI 2841 for 64-bit processors. An x32 process gets access to the 2842 full 64-bit register file and wide data path while leaving 2843 pointers at 32 bits for smaller memory footprint. 2844 2845 You will need a recent binutils (2.22 or later) with 2846 elf32_x86_64 support enabled to compile a kernel with this 2847 option set. 2848 2849config COMPAT_32 2850 def_bool y 2851 depends on IA32_EMULATION || X86_32 2852 select HAVE_UID16 2853 select OLD_SIGSUSPEND3 2854 2855config COMPAT 2856 def_bool y 2857 depends on IA32_EMULATION || X86_X32 2858 2859if COMPAT 2860config COMPAT_FOR_U64_ALIGNMENT 2861 def_bool y 2862 2863config SYSVIPC_COMPAT 2864 def_bool y 2865 depends on SYSVIPC 2866endif 2867 2868endmenu 2869 2870 2871config HAVE_ATOMIC_IOMAP 2872 def_bool y 2873 depends on X86_32 2874 2875source "arch/x86/kvm/Kconfig" 2876 2877source "arch/x86/Kconfig.assembler" 2878