1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_USE_CMPXCHG_LOCKREF 31 select HAVE_ARCH_SOFT_DIRTY 32 select MODULES_USE_ELF_RELA 33 select NEED_DMA_MAP_STATE 34 select SWIOTLB 35 select ARCH_HAS_ELFCORE_COMPAT 36 select ZONE_DMA32 37 38config FORCE_DYNAMIC_FTRACE 39 def_bool y 40 depends on X86_32 41 depends on FUNCTION_TRACER 42 select DYNAMIC_FTRACE 43 help 44 We keep the static function tracing (!DYNAMIC_FTRACE) around 45 in order to test the non static function tracing in the 46 generic code, as other architectures still use it. But we 47 only need to keep it around for x86_64. No need to keep it 48 for x86_32. For x86_32, force DYNAMIC_FTRACE. 49# 50# Arch settings 51# 52# ( Note that options that are marked 'if X86_64' could in principle be 53# ported to 32-bit as well. ) 54# 55config X86 56 def_bool y 57 # 58 # Note: keep this list sorted alphabetically 59 # 60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 62 select ARCH_32BIT_OFF_T if X86_32 63 select ARCH_CLOCKSOURCE_INIT 64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 71 select ARCH_HAS_CACHE_LINE_SIZE 72 select ARCH_HAS_CURRENT_STACK_POINTER 73 select ARCH_HAS_DEBUG_VIRTUAL 74 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 75 select ARCH_HAS_DEVMEM_IS_ALLOWED 76 select ARCH_HAS_EARLY_DEBUG if KGDB 77 select ARCH_HAS_ELF_RANDOMIZE 78 select ARCH_HAS_FAST_MULTIPLIER 79 select ARCH_HAS_FILTER_PGPROT 80 select ARCH_HAS_FORTIFY_SOURCE 81 select ARCH_HAS_GCOV_PROFILE_ALL 82 select ARCH_HAS_KCOV if X86_64 83 select ARCH_HAS_MEM_ENCRYPT 84 select ARCH_HAS_MEMBARRIER_SYNC_CORE 85 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 86 select ARCH_HAS_PMEM_API if X86_64 87 select ARCH_HAS_PTE_DEVMAP if X86_64 88 select ARCH_HAS_PTE_SPECIAL 89 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 90 select ARCH_HAS_COPY_MC if X86_64 91 select ARCH_HAS_SET_MEMORY 92 select ARCH_HAS_SET_DIRECT_MAP 93 select ARCH_HAS_STRICT_KERNEL_RWX 94 select ARCH_HAS_STRICT_MODULE_RWX 95 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 96 select ARCH_HAS_SYSCALL_WRAPPER 97 select ARCH_HAS_UBSAN_SANITIZE_ALL 98 select ARCH_HAS_DEBUG_WX 99 select ARCH_HAS_ZONE_DMA_SET if EXPERT 100 select ARCH_HAVE_NMI_SAFE_CMPXCHG 101 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 102 select ARCH_MIGHT_HAVE_PC_PARPORT 103 select ARCH_MIGHT_HAVE_PC_SERIO 104 select ARCH_STACKWALK 105 select ARCH_SUPPORTS_ACPI 106 select ARCH_SUPPORTS_ATOMIC_RMW 107 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 108 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 109 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 110 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 111 select ARCH_SUPPORTS_LTO_CLANG 112 select ARCH_SUPPORTS_LTO_CLANG_THIN 113 select ARCH_USE_BUILTIN_BSWAP 114 select ARCH_USE_MEMTEST 115 select ARCH_USE_QUEUED_RWLOCKS 116 select ARCH_USE_QUEUED_SPINLOCKS 117 select ARCH_USE_SYM_ANNOTATIONS 118 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 119 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 120 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 121 select ARCH_WANTS_NO_INSTR 122 select ARCH_WANT_GENERAL_HUGETLB 123 select ARCH_WANT_HUGE_PMD_SHARE 124 select ARCH_WANT_LD_ORPHAN_WARN 125 select ARCH_WANTS_THP_SWAP if X86_64 126 select ARCH_HAS_PARANOID_L1D_FLUSH 127 select BUILDTIME_TABLE_SORT 128 select CLKEVT_I8253 129 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 130 select CLOCKSOURCE_WATCHDOG 131 select DCACHE_WORD_ACCESS 132 select DYNAMIC_SIGFRAME 133 select EDAC_ATOMIC_SCRUB 134 select EDAC_SUPPORT 135 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 136 select GENERIC_CLOCKEVENTS_MIN_ADJUST 137 select GENERIC_CMOS_UPDATE 138 select GENERIC_CPU_AUTOPROBE 139 select GENERIC_CPU_VULNERABILITIES 140 select GENERIC_EARLY_IOREMAP 141 select GENERIC_ENTRY 142 select GENERIC_IOMAP 143 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 144 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 145 select GENERIC_IRQ_MIGRATION if SMP 146 select GENERIC_IRQ_PROBE 147 select GENERIC_IRQ_RESERVATION_MODE 148 select GENERIC_IRQ_SHOW 149 select GENERIC_PENDING_IRQ if SMP 150 select GENERIC_PTDUMP 151 select GENERIC_SMP_IDLE_THREAD 152 select GENERIC_TIME_VSYSCALL 153 select GENERIC_GETTIMEOFDAY 154 select GENERIC_VDSO_TIME_NS 155 select GUP_GET_PTE_LOW_HIGH if X86_PAE 156 select HARDIRQS_SW_RESEND 157 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 158 select HAVE_ACPI_APEI if ACPI 159 select HAVE_ACPI_APEI_NMI if ACPI 160 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 161 select HAVE_ARCH_AUDITSYSCALL 162 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 163 select HAVE_ARCH_HUGE_VMALLOC if X86_64 164 select HAVE_ARCH_JUMP_LABEL 165 select HAVE_ARCH_JUMP_LABEL_RELATIVE 166 select HAVE_ARCH_KASAN if X86_64 167 select HAVE_ARCH_KASAN_VMALLOC if X86_64 168 select HAVE_ARCH_KFENCE 169 select HAVE_ARCH_KGDB 170 select HAVE_ARCH_MMAP_RND_BITS if MMU 171 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 172 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 173 select HAVE_ARCH_PREL32_RELOCATIONS 174 select HAVE_ARCH_SECCOMP_FILTER 175 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 176 select HAVE_ARCH_STACKLEAK 177 select HAVE_ARCH_TRACEHOOK 178 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 179 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 180 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 181 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 182 select HAVE_ARCH_VMAP_STACK if X86_64 183 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 184 select HAVE_ARCH_WITHIN_STACK_FRAMES 185 select HAVE_ASM_MODVERSIONS 186 select HAVE_CMPXCHG_DOUBLE 187 select HAVE_CMPXCHG_LOCAL 188 select HAVE_CONTEXT_TRACKING if X86_64 189 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING 190 select HAVE_C_RECORDMCOUNT 191 select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION 192 select HAVE_BUILDTIME_MCOUNT_SORT 193 select HAVE_DEBUG_KMEMLEAK 194 select HAVE_DMA_CONTIGUOUS 195 select HAVE_DYNAMIC_FTRACE 196 select HAVE_DYNAMIC_FTRACE_WITH_REGS 197 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 198 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 199 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 200 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 201 select HAVE_EBPF_JIT 202 select HAVE_EFFICIENT_UNALIGNED_ACCESS 203 select HAVE_EISA 204 select HAVE_EXIT_THREAD 205 select HAVE_FAST_GUP 206 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 207 select HAVE_FTRACE_MCOUNT_RECORD 208 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 209 select HAVE_FUNCTION_TRACER 210 select HAVE_GCC_PLUGINS 211 select HAVE_HW_BREAKPOINT 212 select HAVE_IOREMAP_PROT 213 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 214 select HAVE_IRQ_TIME_ACCOUNTING 215 select HAVE_KERNEL_BZIP2 216 select HAVE_KERNEL_GZIP 217 select HAVE_KERNEL_LZ4 218 select HAVE_KERNEL_LZMA 219 select HAVE_KERNEL_LZO 220 select HAVE_KERNEL_XZ 221 select HAVE_KERNEL_ZSTD 222 select HAVE_KPROBES 223 select HAVE_KPROBES_ON_FTRACE 224 select HAVE_FUNCTION_ERROR_INJECTION 225 select HAVE_KRETPROBES 226 select HAVE_RETHOOK 227 select HAVE_KVM 228 select HAVE_LIVEPATCH if X86_64 229 select HAVE_MIXED_BREAKPOINTS_REGS 230 select HAVE_MOD_ARCH_SPECIFIC 231 select HAVE_MOVE_PMD 232 select HAVE_MOVE_PUD 233 select HAVE_NMI 234 select HAVE_OPTPROBES 235 select HAVE_PCSPKR_PLATFORM 236 select HAVE_PERF_EVENTS 237 select HAVE_PERF_EVENTS_NMI 238 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 239 select HAVE_PCI 240 select HAVE_PERF_REGS 241 select HAVE_PERF_USER_STACK_DUMP 242 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 243 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 244 select HAVE_REGS_AND_STACK_ACCESS_API 245 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION 246 select HAVE_FUNCTION_ARG_ACCESS_API 247 select HAVE_SETUP_PER_CPU_AREA 248 select HAVE_SOFTIRQ_ON_OWN_STACK 249 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 250 select HAVE_STACK_VALIDATION if X86_64 251 select HAVE_STATIC_CALL 252 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION 253 select HAVE_PREEMPT_DYNAMIC_CALL 254 select HAVE_RSEQ 255 select HAVE_SYSCALL_TRACEPOINTS 256 select HAVE_UNSTABLE_SCHED_CLOCK 257 select HAVE_USER_RETURN_NOTIFIER 258 select HAVE_GENERIC_VDSO 259 select HOTPLUG_SMT if SMP 260 select IRQ_FORCED_THREADING 261 select NEED_PER_CPU_EMBED_FIRST_CHUNK 262 select NEED_PER_CPU_PAGE_FIRST_CHUNK 263 select NEED_SG_DMA_LENGTH 264 select PCI_DOMAINS if PCI 265 select PCI_LOCKLESS_CONFIG if PCI 266 select PERF_EVENTS 267 select RTC_LIB 268 select RTC_MC146818_LIB 269 select SPARSE_IRQ 270 select SRCU 271 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE) 272 select SYSCTL_EXCEPTION_TRACE 273 select THREAD_INFO_IN_TASK 274 select TRACE_IRQFLAGS_SUPPORT 275 select USER_STACKTRACE_SUPPORT 276 select VIRT_TO_BUS 277 select HAVE_ARCH_KCSAN if X86_64 278 select X86_FEATURE_NAMES if PROC_FS 279 select PROC_PID_ARCH_STATUS if PROC_FS 280 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 281 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 282 283config INSTRUCTION_DECODER 284 def_bool y 285 depends on KPROBES || PERF_EVENTS || UPROBES 286 287config OUTPUT_FORMAT 288 string 289 default "elf32-i386" if X86_32 290 default "elf64-x86-64" if X86_64 291 292config LOCKDEP_SUPPORT 293 def_bool y 294 295config STACKTRACE_SUPPORT 296 def_bool y 297 298config MMU 299 def_bool y 300 301config ARCH_MMAP_RND_BITS_MIN 302 default 28 if 64BIT 303 default 8 304 305config ARCH_MMAP_RND_BITS_MAX 306 default 32 if 64BIT 307 default 16 308 309config ARCH_MMAP_RND_COMPAT_BITS_MIN 310 default 8 311 312config ARCH_MMAP_RND_COMPAT_BITS_MAX 313 default 16 314 315config SBUS 316 bool 317 318config GENERIC_ISA_DMA 319 def_bool y 320 depends on ISA_DMA_API 321 322config GENERIC_BUG 323 def_bool y 324 depends on BUG 325 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 326 327config GENERIC_BUG_RELATIVE_POINTERS 328 bool 329 330config ARCH_MAY_HAVE_PC_FDC 331 def_bool y 332 depends on ISA_DMA_API 333 334config GENERIC_CALIBRATE_DELAY 335 def_bool y 336 337config ARCH_HAS_CPU_RELAX 338 def_bool y 339 340config ARCH_HIBERNATION_POSSIBLE 341 def_bool y 342 343config ARCH_NR_GPIO 344 int 345 default 1024 if X86_64 346 default 512 347 348config ARCH_SUSPEND_POSSIBLE 349 def_bool y 350 351config AUDIT_ARCH 352 def_bool y if X86_64 353 354config KASAN_SHADOW_OFFSET 355 hex 356 depends on KASAN 357 default 0xdffffc0000000000 358 359config HAVE_INTEL_TXT 360 def_bool y 361 depends on INTEL_IOMMU && ACPI 362 363config X86_32_SMP 364 def_bool y 365 depends on X86_32 && SMP 366 367config X86_64_SMP 368 def_bool y 369 depends on X86_64 && SMP 370 371config ARCH_SUPPORTS_UPROBES 372 def_bool y 373 374config FIX_EARLYCON_MEM 375 def_bool y 376 377config DYNAMIC_PHYSICAL_MASK 378 bool 379 380config PGTABLE_LEVELS 381 int 382 default 5 if X86_5LEVEL 383 default 4 if X86_64 384 default 3 if X86_PAE 385 default 2 386 387config CC_HAS_SANE_STACKPROTECTOR 388 bool 389 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT 390 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC)) 391 help 392 We have to make sure stack protector is unconditionally disabled if 393 the compiler produces broken code or if it does not let us control 394 the segment on 32-bit kernels. 395 396menu "Processor type and features" 397 398config SMP 399 bool "Symmetric multi-processing support" 400 help 401 This enables support for systems with more than one CPU. If you have 402 a system with only one CPU, say N. If you have a system with more 403 than one CPU, say Y. 404 405 If you say N here, the kernel will run on uni- and multiprocessor 406 machines, but will use only one CPU of a multiprocessor machine. If 407 you say Y here, the kernel will run on many, but not all, 408 uniprocessor machines. On a uniprocessor machine, the kernel 409 will run faster if you say N here. 410 411 Note that if you say Y here and choose architecture "586" or 412 "Pentium" under "Processor family", the kernel will not work on 486 413 architectures. Similarly, multiprocessor kernels for the "PPro" 414 architecture may not work on all Pentium based boards. 415 416 People using multiprocessor machines who say Y here should also say 417 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 418 Management" code will be disabled if you say Y here. 419 420 See also <file:Documentation/x86/i386/IO-APIC.rst>, 421 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 422 <http://www.tldp.org/docs.html#howto>. 423 424 If you don't know what to do here, say N. 425 426config X86_FEATURE_NAMES 427 bool "Processor feature human-readable names" if EMBEDDED 428 default y 429 help 430 This option compiles in a table of x86 feature bits and corresponding 431 names. This is required to support /proc/cpuinfo and a few kernel 432 messages. You can disable this to save space, at the expense of 433 making those few kernel messages show numeric feature bits instead. 434 435 If in doubt, say Y. 436 437config X86_X2APIC 438 bool "Support x2apic" 439 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 440 help 441 This enables x2apic support on CPUs that have this feature. 442 443 This allows 32-bit apic IDs (so it can support very large systems), 444 and accesses the local apic via MSRs not via mmio. 445 446 If you don't know what to do here, say N. 447 448config X86_MPPARSE 449 bool "Enable MPS table" if ACPI 450 default y 451 depends on X86_LOCAL_APIC 452 help 453 For old smp systems that do not have proper acpi support. Newer systems 454 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 455 456config GOLDFISH 457 def_bool y 458 depends on X86_GOLDFISH 459 460config RETPOLINE 461 bool "Avoid speculative indirect branches in kernel" 462 default y 463 help 464 Compile kernel with the retpoline compiler options to guard against 465 kernel-to-user data leaks by avoiding speculative indirect 466 branches. Requires a compiler with -mindirect-branch=thunk-extern 467 support for full protection. The kernel may run slower. 468 469config CC_HAS_SLS 470 def_bool $(cc-option,-mharden-sls=all) 471 472config SLS 473 bool "Mitigate Straight-Line-Speculation" 474 depends on CC_HAS_SLS && X86_64 475 default n 476 help 477 Compile the kernel with straight-line-speculation options to guard 478 against straight line speculation. The kernel image might be slightly 479 larger. 480 481config X86_CPU_RESCTRL 482 bool "x86 CPU resource control support" 483 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 484 select KERNFS 485 select PROC_CPU_RESCTRL if PROC_FS 486 help 487 Enable x86 CPU resource control support. 488 489 Provide support for the allocation and monitoring of system resources 490 usage by the CPU. 491 492 Intel calls this Intel Resource Director Technology 493 (Intel(R) RDT). More information about RDT can be found in the 494 Intel x86 Architecture Software Developer Manual. 495 496 AMD calls this AMD Platform Quality of Service (AMD QoS). 497 More information about AMD QoS can be found in the AMD64 Technology 498 Platform Quality of Service Extensions manual. 499 500 Say N if unsure. 501 502if X86_32 503config X86_BIGSMP 504 bool "Support for big SMP systems with more than 8 CPUs" 505 depends on SMP 506 help 507 This option is needed for the systems that have more than 8 CPUs. 508 509config X86_EXTENDED_PLATFORM 510 bool "Support for extended (non-PC) x86 platforms" 511 default y 512 help 513 If you disable this option then the kernel will only support 514 standard PC platforms. (which covers the vast majority of 515 systems out there.) 516 517 If you enable this option then you'll be able to select support 518 for the following (non-PC) 32 bit x86 platforms: 519 Goldfish (Android emulator) 520 AMD Elan 521 RDC R-321x SoC 522 SGI 320/540 (Visual Workstation) 523 STA2X11-based (e.g. Northville) 524 Moorestown MID devices 525 526 If you have one of these systems, or if you want to build a 527 generic distribution kernel, say Y here - otherwise say N. 528endif 529 530if X86_64 531config X86_EXTENDED_PLATFORM 532 bool "Support for extended (non-PC) x86 platforms" 533 default y 534 help 535 If you disable this option then the kernel will only support 536 standard PC platforms. (which covers the vast majority of 537 systems out there.) 538 539 If you enable this option then you'll be able to select support 540 for the following (non-PC) 64 bit x86 platforms: 541 Numascale NumaChip 542 ScaleMP vSMP 543 SGI Ultraviolet 544 545 If you have one of these systems, or if you want to build a 546 generic distribution kernel, say Y here - otherwise say N. 547endif 548# This is an alphabetically sorted list of 64 bit extended platforms 549# Please maintain the alphabetic order if and when there are additions 550config X86_NUMACHIP 551 bool "Numascale NumaChip" 552 depends on X86_64 553 depends on X86_EXTENDED_PLATFORM 554 depends on NUMA 555 depends on SMP 556 depends on X86_X2APIC 557 depends on PCI_MMCONFIG 558 help 559 Adds support for Numascale NumaChip large-SMP systems. Needed to 560 enable more than ~168 cores. 561 If you don't have one of these, you should say N here. 562 563config X86_VSMP 564 bool "ScaleMP vSMP" 565 select HYPERVISOR_GUEST 566 select PARAVIRT 567 depends on X86_64 && PCI 568 depends on X86_EXTENDED_PLATFORM 569 depends on SMP 570 help 571 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 572 supposed to run on these EM64T-based machines. Only choose this option 573 if you have one of these machines. 574 575config X86_UV 576 bool "SGI Ultraviolet" 577 depends on X86_64 578 depends on X86_EXTENDED_PLATFORM 579 depends on NUMA 580 depends on EFI 581 depends on KEXEC_CORE 582 depends on X86_X2APIC 583 depends on PCI 584 help 585 This option is needed in order to support SGI Ultraviolet systems. 586 If you don't have one of these, you should say N here. 587 588# Following is an alphabetically sorted list of 32 bit extended platforms 589# Please maintain the alphabetic order if and when there are additions 590 591config X86_GOLDFISH 592 bool "Goldfish (Virtual Platform)" 593 depends on X86_EXTENDED_PLATFORM 594 help 595 Enable support for the Goldfish virtual platform used primarily 596 for Android development. Unless you are building for the Android 597 Goldfish emulator say N here. 598 599config X86_INTEL_CE 600 bool "CE4100 TV platform" 601 depends on PCI 602 depends on PCI_GODIRECT 603 depends on X86_IO_APIC 604 depends on X86_32 605 depends on X86_EXTENDED_PLATFORM 606 select X86_REBOOTFIXUPS 607 select OF 608 select OF_EARLY_FLATTREE 609 help 610 Select for the Intel CE media processor (CE4100) SOC. 611 This option compiles in support for the CE4100 SOC for settop 612 boxes and media devices. 613 614config X86_INTEL_MID 615 bool "Intel MID platform support" 616 depends on X86_EXTENDED_PLATFORM 617 depends on X86_PLATFORM_DEVICES 618 depends on PCI 619 depends on X86_64 || (PCI_GOANY && X86_32) 620 depends on X86_IO_APIC 621 select I2C 622 select DW_APB_TIMER 623 select INTEL_SCU_PCI 624 help 625 Select to build a kernel capable of supporting Intel MID (Mobile 626 Internet Device) platform systems which do not have the PCI legacy 627 interfaces. If you are building for a PC class system say N here. 628 629 Intel MID platforms are based on an Intel processor and chipset which 630 consume less power than most of the x86 derivatives. 631 632config X86_INTEL_QUARK 633 bool "Intel Quark platform support" 634 depends on X86_32 635 depends on X86_EXTENDED_PLATFORM 636 depends on X86_PLATFORM_DEVICES 637 depends on X86_TSC 638 depends on PCI 639 depends on PCI_GOANY 640 depends on X86_IO_APIC 641 select IOSF_MBI 642 select INTEL_IMR 643 select COMMON_CLK 644 help 645 Select to include support for Quark X1000 SoC. 646 Say Y here if you have a Quark based system such as the Arduino 647 compatible Intel Galileo. 648 649config X86_INTEL_LPSS 650 bool "Intel Low Power Subsystem Support" 651 depends on X86 && ACPI && PCI 652 select COMMON_CLK 653 select PINCTRL 654 select IOSF_MBI 655 help 656 Select to build support for Intel Low Power Subsystem such as 657 found on Intel Lynxpoint PCH. Selecting this option enables 658 things like clock tree (common clock framework) and pincontrol 659 which are needed by the LPSS peripheral drivers. 660 661config X86_AMD_PLATFORM_DEVICE 662 bool "AMD ACPI2Platform devices support" 663 depends on ACPI 664 select COMMON_CLK 665 select PINCTRL 666 help 667 Select to interpret AMD specific ACPI device to platform device 668 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 669 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 670 implemented under PINCTRL subsystem. 671 672config IOSF_MBI 673 tristate "Intel SoC IOSF Sideband support for SoC platforms" 674 depends on PCI 675 help 676 This option enables sideband register access support for Intel SoC 677 platforms. On these platforms the IOSF sideband is used in lieu of 678 MSR's for some register accesses, mostly but not limited to thermal 679 and power. Drivers may query the availability of this device to 680 determine if they need the sideband in order to work on these 681 platforms. The sideband is available on the following SoC products. 682 This list is not meant to be exclusive. 683 - BayTrail 684 - Braswell 685 - Quark 686 687 You should say Y if you are running a kernel on one of these SoC's. 688 689config IOSF_MBI_DEBUG 690 bool "Enable IOSF sideband access through debugfs" 691 depends on IOSF_MBI && DEBUG_FS 692 help 693 Select this option to expose the IOSF sideband access registers (MCR, 694 MDR, MCRX) through debugfs to write and read register information from 695 different units on the SoC. This is most useful for obtaining device 696 state information for debug and analysis. As this is a general access 697 mechanism, users of this option would have specific knowledge of the 698 device they want to access. 699 700 If you don't require the option or are in doubt, say N. 701 702config X86_RDC321X 703 bool "RDC R-321x SoC" 704 depends on X86_32 705 depends on X86_EXTENDED_PLATFORM 706 select M486 707 select X86_REBOOTFIXUPS 708 help 709 This option is needed for RDC R-321x system-on-chip, also known 710 as R-8610-(G). 711 If you don't have one of these chips, you should say N here. 712 713config X86_32_NON_STANDARD 714 bool "Support non-standard 32-bit SMP architectures" 715 depends on X86_32 && SMP 716 depends on X86_EXTENDED_PLATFORM 717 help 718 This option compiles in the bigsmp and STA2X11 default 719 subarchitectures. It is intended for a generic binary 720 kernel. If you select them all, kernel will probe it one by 721 one and will fallback to default. 722 723# Alphabetically sorted list of Non standard 32 bit platforms 724 725config X86_SUPPORTS_MEMORY_FAILURE 726 def_bool y 727 # MCE code calls memory_failure(): 728 depends on X86_MCE 729 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 730 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 731 depends on X86_64 || !SPARSEMEM 732 select ARCH_SUPPORTS_MEMORY_FAILURE 733 734config STA2X11 735 bool "STA2X11 Companion Chip Support" 736 depends on X86_32_NON_STANDARD && PCI 737 select SWIOTLB 738 select MFD_STA2X11 739 select GPIOLIB 740 help 741 This adds support for boards based on the STA2X11 IO-Hub, 742 a.k.a. "ConneXt". The chip is used in place of the standard 743 PC chipset, so all "standard" peripherals are missing. If this 744 option is selected the kernel will still be able to boot on 745 standard PC machines. 746 747config X86_32_IRIS 748 tristate "Eurobraille/Iris poweroff module" 749 depends on X86_32 750 help 751 The Iris machines from EuroBraille do not have APM or ACPI support 752 to shut themselves down properly. A special I/O sequence is 753 needed to do so, which is what this module does at 754 kernel shutdown. 755 756 This is only for Iris machines from EuroBraille. 757 758 If unused, say N. 759 760config SCHED_OMIT_FRAME_POINTER 761 def_bool y 762 prompt "Single-depth WCHAN output" 763 depends on X86 764 help 765 Calculate simpler /proc/<PID>/wchan values. If this option 766 is disabled then wchan values will recurse back to the 767 caller function. This provides more accurate wchan values, 768 at the expense of slightly more scheduling overhead. 769 770 If in doubt, say "Y". 771 772menuconfig HYPERVISOR_GUEST 773 bool "Linux guest support" 774 help 775 Say Y here to enable options for running Linux under various hyper- 776 visors. This option enables basic hypervisor detection and platform 777 setup. 778 779 If you say N, all options in this submenu will be skipped and 780 disabled, and Linux guest support won't be built in. 781 782if HYPERVISOR_GUEST 783 784config PARAVIRT 785 bool "Enable paravirtualization code" 786 depends on HAVE_STATIC_CALL 787 help 788 This changes the kernel so it can modify itself when it is run 789 under a hypervisor, potentially improving performance significantly 790 over full virtualization. However, when run without a hypervisor 791 the kernel is theoretically slower and slightly larger. 792 793config PARAVIRT_XXL 794 bool 795 796config PARAVIRT_DEBUG 797 bool "paravirt-ops debugging" 798 depends on PARAVIRT && DEBUG_KERNEL 799 help 800 Enable to debug paravirt_ops internals. Specifically, BUG if 801 a paravirt_op is missing when it is called. 802 803config PARAVIRT_SPINLOCKS 804 bool "Paravirtualization layer for spinlocks" 805 depends on PARAVIRT && SMP 806 help 807 Paravirtualized spinlocks allow a pvops backend to replace the 808 spinlock implementation with something virtualization-friendly 809 (for example, block the virtual CPU rather than spinning). 810 811 It has a minimal impact on native kernels and gives a nice performance 812 benefit on paravirtualized KVM / Xen kernels. 813 814 If you are unsure how to answer this question, answer Y. 815 816config X86_HV_CALLBACK_VECTOR 817 def_bool n 818 819source "arch/x86/xen/Kconfig" 820 821config KVM_GUEST 822 bool "KVM Guest support (including kvmclock)" 823 depends on PARAVIRT 824 select PARAVIRT_CLOCK 825 select ARCH_CPUIDLE_HALTPOLL 826 select X86_HV_CALLBACK_VECTOR 827 default y 828 help 829 This option enables various optimizations for running under the KVM 830 hypervisor. It includes a paravirtualized clock, so that instead 831 of relying on a PIT (or probably other) emulation by the 832 underlying device model, the host provides the guest with 833 timing infrastructure such as time of day, and system time 834 835config ARCH_CPUIDLE_HALTPOLL 836 def_bool n 837 prompt "Disable host haltpoll when loading haltpoll driver" 838 help 839 If virtualized under KVM, disable host haltpoll. 840 841config PVH 842 bool "Support for running PVH guests" 843 help 844 This option enables the PVH entry point for guest virtual machines 845 as specified in the x86/HVM direct boot ABI. 846 847config PARAVIRT_TIME_ACCOUNTING 848 bool "Paravirtual steal time accounting" 849 depends on PARAVIRT 850 help 851 Select this option to enable fine granularity task steal time 852 accounting. Time spent executing other tasks in parallel with 853 the current vCPU is discounted from the vCPU power. To account for 854 that, there can be a small performance impact. 855 856 If in doubt, say N here. 857 858config PARAVIRT_CLOCK 859 bool 860 861config JAILHOUSE_GUEST 862 bool "Jailhouse non-root cell support" 863 depends on X86_64 && PCI 864 select X86_PM_TIMER 865 help 866 This option allows to run Linux as guest in a Jailhouse non-root 867 cell. You can leave this option disabled if you only want to start 868 Jailhouse and run Linux afterwards in the root cell. 869 870config ACRN_GUEST 871 bool "ACRN Guest support" 872 depends on X86_64 873 select X86_HV_CALLBACK_VECTOR 874 help 875 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 876 a flexible, lightweight reference open-source hypervisor, built with 877 real-time and safety-criticality in mind. It is built for embedded 878 IOT with small footprint and real-time features. More details can be 879 found in https://projectacrn.org/. 880 881endif #HYPERVISOR_GUEST 882 883source "arch/x86/Kconfig.cpu" 884 885config HPET_TIMER 886 def_bool X86_64 887 prompt "HPET Timer Support" if X86_32 888 help 889 Use the IA-PC HPET (High Precision Event Timer) to manage 890 time in preference to the PIT and RTC, if a HPET is 891 present. 892 HPET is the next generation timer replacing legacy 8254s. 893 The HPET provides a stable time base on SMP 894 systems, unlike the TSC, but it is more expensive to access, 895 as it is off-chip. The interface used is documented 896 in the HPET spec, revision 1. 897 898 You can safely choose Y here. However, HPET will only be 899 activated if the platform and the BIOS support this feature. 900 Otherwise the 8254 will be used for timing services. 901 902 Choose N to continue using the legacy 8254 timer. 903 904config HPET_EMULATE_RTC 905 def_bool y 906 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 907 908# Mark as expert because too many people got it wrong. 909# The code disables itself when not needed. 910config DMI 911 default y 912 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 913 bool "Enable DMI scanning" if EXPERT 914 help 915 Enabled scanning of DMI to identify machine quirks. Say Y 916 here unless you have verified that your setup is not 917 affected by entries in the DMI blacklist. Required by PNP 918 BIOS code. 919 920config GART_IOMMU 921 bool "Old AMD GART IOMMU support" 922 select DMA_OPS 923 select IOMMU_HELPER 924 select SWIOTLB 925 depends on X86_64 && PCI && AMD_NB 926 help 927 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 928 GART based hardware IOMMUs. 929 930 The GART supports full DMA access for devices with 32-bit access 931 limitations, on systems with more than 3 GB. This is usually needed 932 for USB, sound, many IDE/SATA chipsets and some other devices. 933 934 Newer systems typically have a modern AMD IOMMU, supported via 935 the CONFIG_AMD_IOMMU=y config option. 936 937 In normal configurations this driver is only active when needed: 938 there's more than 3 GB of memory and the system contains a 939 32-bit limited device. 940 941 If unsure, say Y. 942 943config MAXSMP 944 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 945 depends on X86_64 && SMP && DEBUG_KERNEL 946 select CPUMASK_OFFSTACK 947 help 948 Enable maximum number of CPUS and NUMA Nodes for this architecture. 949 If unsure, say N. 950 951# 952# The maximum number of CPUs supported: 953# 954# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 955# and which can be configured interactively in the 956# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 957# 958# The ranges are different on 32-bit and 64-bit kernels, depending on 959# hardware capabilities and scalability features of the kernel. 960# 961# ( If MAXSMP is enabled we just use the highest possible value and disable 962# interactive configuration. ) 963# 964 965config NR_CPUS_RANGE_BEGIN 966 int 967 default NR_CPUS_RANGE_END if MAXSMP 968 default 1 if !SMP 969 default 2 970 971config NR_CPUS_RANGE_END 972 int 973 depends on X86_32 974 default 64 if SMP && X86_BIGSMP 975 default 8 if SMP && !X86_BIGSMP 976 default 1 if !SMP 977 978config NR_CPUS_RANGE_END 979 int 980 depends on X86_64 981 default 8192 if SMP && CPUMASK_OFFSTACK 982 default 512 if SMP && !CPUMASK_OFFSTACK 983 default 1 if !SMP 984 985config NR_CPUS_DEFAULT 986 int 987 depends on X86_32 988 default 32 if X86_BIGSMP 989 default 8 if SMP 990 default 1 if !SMP 991 992config NR_CPUS_DEFAULT 993 int 994 depends on X86_64 995 default 8192 if MAXSMP 996 default 64 if SMP 997 default 1 if !SMP 998 999config NR_CPUS 1000 int "Maximum number of CPUs" if SMP && !MAXSMP 1001 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1002 default NR_CPUS_DEFAULT 1003 help 1004 This allows you to specify the maximum number of CPUs which this 1005 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1006 supported value is 8192, otherwise the maximum value is 512. The 1007 minimum value which makes sense is 2. 1008 1009 This is purely to save memory: each supported CPU adds about 8KB 1010 to the kernel image. 1011 1012config SCHED_CLUSTER 1013 bool "Cluster scheduler support" 1014 depends on SMP 1015 default y 1016 help 1017 Cluster scheduler support improves the CPU scheduler's decision 1018 making when dealing with machines that have clusters of CPUs. 1019 Cluster usually means a couple of CPUs which are placed closely 1020 by sharing mid-level caches, last-level cache tags or internal 1021 busses. 1022 1023config SCHED_SMT 1024 def_bool y if SMP 1025 1026config SCHED_MC 1027 def_bool y 1028 prompt "Multi-core scheduler support" 1029 depends on SMP 1030 help 1031 Multi-core scheduler support improves the CPU scheduler's decision 1032 making when dealing with multi-core CPU chips at a cost of slightly 1033 increased overhead in some places. If unsure say N here. 1034 1035config SCHED_MC_PRIO 1036 bool "CPU core priorities scheduler support" 1037 depends on SCHED_MC && CPU_SUP_INTEL 1038 select X86_INTEL_PSTATE 1039 select CPU_FREQ 1040 default y 1041 help 1042 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1043 core ordering determined at manufacturing time, which allows 1044 certain cores to reach higher turbo frequencies (when running 1045 single threaded workloads) than others. 1046 1047 Enabling this kernel feature teaches the scheduler about 1048 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1049 scheduler's CPU selection logic accordingly, so that higher 1050 overall system performance can be achieved. 1051 1052 This feature will have no effect on CPUs without this feature. 1053 1054 If unsure say Y here. 1055 1056config UP_LATE_INIT 1057 def_bool y 1058 depends on !SMP && X86_LOCAL_APIC 1059 1060config X86_UP_APIC 1061 bool "Local APIC support on uniprocessors" if !PCI_MSI 1062 default PCI_MSI 1063 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1064 help 1065 A local APIC (Advanced Programmable Interrupt Controller) is an 1066 integrated interrupt controller in the CPU. If you have a single-CPU 1067 system which has a processor with a local APIC, you can say Y here to 1068 enable and use it. If you say Y here even though your machine doesn't 1069 have a local APIC, then the kernel will still run with no slowdown at 1070 all. The local APIC supports CPU-generated self-interrupts (timer, 1071 performance counters), and the NMI watchdog which detects hard 1072 lockups. 1073 1074config X86_UP_IOAPIC 1075 bool "IO-APIC support on uniprocessors" 1076 depends on X86_UP_APIC 1077 help 1078 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1079 SMP-capable replacement for PC-style interrupt controllers. Most 1080 SMP systems and many recent uniprocessor systems have one. 1081 1082 If you have a single-CPU system with an IO-APIC, you can say Y here 1083 to use it. If you say Y here even though your machine doesn't have 1084 an IO-APIC, then the kernel will still run with no slowdown at all. 1085 1086config X86_LOCAL_APIC 1087 def_bool y 1088 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1089 select IRQ_DOMAIN_HIERARCHY 1090 select PCI_MSI_IRQ_DOMAIN if PCI_MSI 1091 1092config X86_IO_APIC 1093 def_bool y 1094 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1095 1096config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1097 bool "Reroute for broken boot IRQs" 1098 depends on X86_IO_APIC 1099 help 1100 This option enables a workaround that fixes a source of 1101 spurious interrupts. This is recommended when threaded 1102 interrupt handling is used on systems where the generation of 1103 superfluous "boot interrupts" cannot be disabled. 1104 1105 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1106 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1107 kernel does during interrupt handling). On chipsets where this 1108 boot IRQ generation cannot be disabled, this workaround keeps 1109 the original IRQ line masked so that only the equivalent "boot 1110 IRQ" is delivered to the CPUs. The workaround also tells the 1111 kernel to set up the IRQ handler on the boot IRQ line. In this 1112 way only one interrupt is delivered to the kernel. Otherwise 1113 the spurious second interrupt may cause the kernel to bring 1114 down (vital) interrupt lines. 1115 1116 Only affects "broken" chipsets. Interrupt sharing may be 1117 increased on these systems. 1118 1119config X86_MCE 1120 bool "Machine Check / overheating reporting" 1121 select GENERIC_ALLOCATOR 1122 default y 1123 help 1124 Machine Check support allows the processor to notify the 1125 kernel if it detects a problem (e.g. overheating, data corruption). 1126 The action the kernel takes depends on the severity of the problem, 1127 ranging from warning messages to halting the machine. 1128 1129config X86_MCELOG_LEGACY 1130 bool "Support for deprecated /dev/mcelog character device" 1131 depends on X86_MCE 1132 help 1133 Enable support for /dev/mcelog which is needed by the old mcelog 1134 userspace logging daemon. Consider switching to the new generation 1135 rasdaemon solution. 1136 1137config X86_MCE_INTEL 1138 def_bool y 1139 prompt "Intel MCE features" 1140 depends on X86_MCE && X86_LOCAL_APIC 1141 help 1142 Additional support for intel specific MCE features such as 1143 the thermal monitor. 1144 1145config X86_MCE_AMD 1146 def_bool y 1147 prompt "AMD MCE features" 1148 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1149 help 1150 Additional support for AMD specific MCE features such as 1151 the DRAM Error Threshold. 1152 1153config X86_ANCIENT_MCE 1154 bool "Support for old Pentium 5 / WinChip machine checks" 1155 depends on X86_32 && X86_MCE 1156 help 1157 Include support for machine check handling on old Pentium 5 or WinChip 1158 systems. These typically need to be enabled explicitly on the command 1159 line. 1160 1161config X86_MCE_THRESHOLD 1162 depends on X86_MCE_AMD || X86_MCE_INTEL 1163 def_bool y 1164 1165config X86_MCE_INJECT 1166 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1167 tristate "Machine check injector support" 1168 help 1169 Provide support for injecting machine checks for testing purposes. 1170 If you don't know what a machine check is and you don't do kernel 1171 QA it is safe to say n. 1172 1173source "arch/x86/events/Kconfig" 1174 1175config X86_LEGACY_VM86 1176 bool "Legacy VM86 support" 1177 depends on X86_32 1178 help 1179 This option allows user programs to put the CPU into V8086 1180 mode, which is an 80286-era approximation of 16-bit real mode. 1181 1182 Some very old versions of X and/or vbetool require this option 1183 for user mode setting. Similarly, DOSEMU will use it if 1184 available to accelerate real mode DOS programs. However, any 1185 recent version of DOSEMU, X, or vbetool should be fully 1186 functional even without kernel VM86 support, as they will all 1187 fall back to software emulation. Nevertheless, if you are using 1188 a 16-bit DOS program where 16-bit performance matters, vm86 1189 mode might be faster than emulation and you might want to 1190 enable this option. 1191 1192 Note that any app that works on a 64-bit kernel is unlikely to 1193 need this option, as 64-bit kernels don't, and can't, support 1194 V8086 mode. This option is also unrelated to 16-bit protected 1195 mode and is not needed to run most 16-bit programs under Wine. 1196 1197 Enabling this option increases the complexity of the kernel 1198 and slows down exception handling a tiny bit. 1199 1200 If unsure, say N here. 1201 1202config VM86 1203 bool 1204 default X86_LEGACY_VM86 1205 1206config X86_16BIT 1207 bool "Enable support for 16-bit segments" if EXPERT 1208 default y 1209 depends on MODIFY_LDT_SYSCALL 1210 help 1211 This option is required by programs like Wine to run 16-bit 1212 protected mode legacy code on x86 processors. Disabling 1213 this option saves about 300 bytes on i386, or around 6K text 1214 plus 16K runtime memory on x86-64, 1215 1216config X86_ESPFIX32 1217 def_bool y 1218 depends on X86_16BIT && X86_32 1219 1220config X86_ESPFIX64 1221 def_bool y 1222 depends on X86_16BIT && X86_64 1223 1224config X86_VSYSCALL_EMULATION 1225 bool "Enable vsyscall emulation" if EXPERT 1226 default y 1227 depends on X86_64 1228 help 1229 This enables emulation of the legacy vsyscall page. Disabling 1230 it is roughly equivalent to booting with vsyscall=none, except 1231 that it will also disable the helpful warning if a program 1232 tries to use a vsyscall. With this option set to N, offending 1233 programs will just segfault, citing addresses of the form 1234 0xffffffffff600?00. 1235 1236 This option is required by many programs built before 2013, and 1237 care should be used even with newer programs if set to N. 1238 1239 Disabling this option saves about 7K of kernel size and 1240 possibly 4K of additional runtime pagetable memory. 1241 1242config X86_IOPL_IOPERM 1243 bool "IOPERM and IOPL Emulation" 1244 default y 1245 help 1246 This enables the ioperm() and iopl() syscalls which are necessary 1247 for legacy applications. 1248 1249 Legacy IOPL support is an overbroad mechanism which allows user 1250 space aside of accessing all 65536 I/O ports also to disable 1251 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1252 capabilities and permission from potentially active security 1253 modules. 1254 1255 The emulation restricts the functionality of the syscall to 1256 only allowing the full range I/O port access, but prevents the 1257 ability to disable interrupts from user space which would be 1258 granted if the hardware IOPL mechanism would be used. 1259 1260config TOSHIBA 1261 tristate "Toshiba Laptop support" 1262 depends on X86_32 1263 help 1264 This adds a driver to safely access the System Management Mode of 1265 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1266 not work on models with a Phoenix BIOS. The System Management Mode 1267 is used to set the BIOS and power saving options on Toshiba portables. 1268 1269 For information on utilities to make use of this driver see the 1270 Toshiba Linux utilities web site at: 1271 <http://www.buzzard.org.uk/toshiba/>. 1272 1273 Say Y if you intend to run this kernel on a Toshiba portable. 1274 Say N otherwise. 1275 1276config X86_REBOOTFIXUPS 1277 bool "Enable X86 board specific fixups for reboot" 1278 depends on X86_32 1279 help 1280 This enables chipset and/or board specific fixups to be done 1281 in order to get reboot to work correctly. This is only needed on 1282 some combinations of hardware and BIOS. The symptom, for which 1283 this config is intended, is when reboot ends with a stalled/hung 1284 system. 1285 1286 Currently, the only fixup is for the Geode machines using 1287 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1288 1289 Say Y if you want to enable the fixup. Currently, it's safe to 1290 enable this option even if you don't need it. 1291 Say N otherwise. 1292 1293config MICROCODE 1294 bool "CPU microcode loading support" 1295 default y 1296 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1297 help 1298 If you say Y here, you will be able to update the microcode on 1299 Intel and AMD processors. The Intel support is for the IA32 family, 1300 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1301 AMD support is for families 0x10 and later. You will obviously need 1302 the actual microcode binary data itself which is not shipped with 1303 the Linux kernel. 1304 1305 The preferred method to load microcode from a detached initrd is described 1306 in Documentation/x86/microcode.rst. For that you need to enable 1307 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1308 initrd for microcode blobs. 1309 1310 In addition, you can build the microcode into the kernel. For that you 1311 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1312 config option. 1313 1314config MICROCODE_INTEL 1315 bool "Intel microcode loading support" 1316 depends on MICROCODE 1317 default MICROCODE 1318 help 1319 This options enables microcode patch loading support for Intel 1320 processors. 1321 1322 For the current Intel microcode data package go to 1323 <https://downloadcenter.intel.com> and search for 1324 'Linux Processor Microcode Data File'. 1325 1326config MICROCODE_AMD 1327 bool "AMD microcode loading support" 1328 depends on MICROCODE 1329 help 1330 If you select this option, microcode patch loading support for AMD 1331 processors will be enabled. 1332 1333config MICROCODE_OLD_INTERFACE 1334 bool "Ancient loading interface (DEPRECATED)" 1335 default n 1336 depends on MICROCODE 1337 help 1338 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface 1339 which was used by userspace tools like iucode_tool and microcode.ctl. 1340 It is inadequate because it runs too late to be able to properly 1341 load microcode on a machine and it needs special tools. Instead, you 1342 should've switched to the early loading method with the initrd or 1343 builtin microcode by now: Documentation/x86/microcode.rst 1344 1345config X86_MSR 1346 tristate "/dev/cpu/*/msr - Model-specific register support" 1347 help 1348 This device gives privileged processes access to the x86 1349 Model-Specific Registers (MSRs). It is a character device with 1350 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1351 MSR accesses are directed to a specific CPU on multi-processor 1352 systems. 1353 1354config X86_CPUID 1355 tristate "/dev/cpu/*/cpuid - CPU information support" 1356 help 1357 This device gives processes access to the x86 CPUID instruction to 1358 be executed on a specific processor. It is a character device 1359 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1360 /dev/cpu/31/cpuid. 1361 1362choice 1363 prompt "High Memory Support" 1364 default HIGHMEM4G 1365 depends on X86_32 1366 1367config NOHIGHMEM 1368 bool "off" 1369 help 1370 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1371 However, the address space of 32-bit x86 processors is only 4 1372 Gigabytes large. That means that, if you have a large amount of 1373 physical memory, not all of it can be "permanently mapped" by the 1374 kernel. The physical memory that's not permanently mapped is called 1375 "high memory". 1376 1377 If you are compiling a kernel which will never run on a machine with 1378 more than 1 Gigabyte total physical RAM, answer "off" here (default 1379 choice and suitable for most users). This will result in a "3GB/1GB" 1380 split: 3GB are mapped so that each process sees a 3GB virtual memory 1381 space and the remaining part of the 4GB virtual memory space is used 1382 by the kernel to permanently map as much physical memory as 1383 possible. 1384 1385 If the machine has between 1 and 4 Gigabytes physical RAM, then 1386 answer "4GB" here. 1387 1388 If more than 4 Gigabytes is used then answer "64GB" here. This 1389 selection turns Intel PAE (Physical Address Extension) mode on. 1390 PAE implements 3-level paging on IA32 processors. PAE is fully 1391 supported by Linux, PAE mode is implemented on all recent Intel 1392 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1393 then the kernel will not boot on CPUs that don't support PAE! 1394 1395 The actual amount of total physical memory will either be 1396 auto detected or can be forced by using a kernel command line option 1397 such as "mem=256M". (Try "man bootparam" or see the documentation of 1398 your boot loader (lilo or loadlin) about how to pass options to the 1399 kernel at boot time.) 1400 1401 If unsure, say "off". 1402 1403config HIGHMEM4G 1404 bool "4GB" 1405 help 1406 Select this if you have a 32-bit processor and between 1 and 4 1407 gigabytes of physical RAM. 1408 1409config HIGHMEM64G 1410 bool "64GB" 1411 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1412 select X86_PAE 1413 help 1414 Select this if you have a 32-bit processor and more than 4 1415 gigabytes of physical RAM. 1416 1417endchoice 1418 1419choice 1420 prompt "Memory split" if EXPERT 1421 default VMSPLIT_3G 1422 depends on X86_32 1423 help 1424 Select the desired split between kernel and user memory. 1425 1426 If the address range available to the kernel is less than the 1427 physical memory installed, the remaining memory will be available 1428 as "high memory". Accessing high memory is a little more costly 1429 than low memory, as it needs to be mapped into the kernel first. 1430 Note that increasing the kernel address space limits the range 1431 available to user programs, making the address space there 1432 tighter. Selecting anything other than the default 3G/1G split 1433 will also likely make your kernel incompatible with binary-only 1434 kernel modules. 1435 1436 If you are not absolutely sure what you are doing, leave this 1437 option alone! 1438 1439 config VMSPLIT_3G 1440 bool "3G/1G user/kernel split" 1441 config VMSPLIT_3G_OPT 1442 depends on !X86_PAE 1443 bool "3G/1G user/kernel split (for full 1G low memory)" 1444 config VMSPLIT_2G 1445 bool "2G/2G user/kernel split" 1446 config VMSPLIT_2G_OPT 1447 depends on !X86_PAE 1448 bool "2G/2G user/kernel split (for full 2G low memory)" 1449 config VMSPLIT_1G 1450 bool "1G/3G user/kernel split" 1451endchoice 1452 1453config PAGE_OFFSET 1454 hex 1455 default 0xB0000000 if VMSPLIT_3G_OPT 1456 default 0x80000000 if VMSPLIT_2G 1457 default 0x78000000 if VMSPLIT_2G_OPT 1458 default 0x40000000 if VMSPLIT_1G 1459 default 0xC0000000 1460 depends on X86_32 1461 1462config HIGHMEM 1463 def_bool y 1464 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1465 1466config X86_PAE 1467 bool "PAE (Physical Address Extension) Support" 1468 depends on X86_32 && !HIGHMEM4G 1469 select PHYS_ADDR_T_64BIT 1470 select SWIOTLB 1471 help 1472 PAE is required for NX support, and furthermore enables 1473 larger swapspace support for non-overcommit purposes. It 1474 has the cost of more pagetable lookup overhead, and also 1475 consumes more pagetable space per process. 1476 1477config X86_5LEVEL 1478 bool "Enable 5-level page tables support" 1479 default y 1480 select DYNAMIC_MEMORY_LAYOUT 1481 select SPARSEMEM_VMEMMAP 1482 depends on X86_64 1483 help 1484 5-level paging enables access to larger address space: 1485 upto 128 PiB of virtual address space and 4 PiB of 1486 physical address space. 1487 1488 It will be supported by future Intel CPUs. 1489 1490 A kernel with the option enabled can be booted on machines that 1491 support 4- or 5-level paging. 1492 1493 See Documentation/x86/x86_64/5level-paging.rst for more 1494 information. 1495 1496 Say N if unsure. 1497 1498config X86_DIRECT_GBPAGES 1499 def_bool y 1500 depends on X86_64 1501 help 1502 Certain kernel features effectively disable kernel 1503 linear 1 GB mappings (even if the CPU otherwise 1504 supports them), so don't confuse the user by printing 1505 that we have them enabled. 1506 1507config X86_CPA_STATISTICS 1508 bool "Enable statistic for Change Page Attribute" 1509 depends on DEBUG_FS 1510 help 1511 Expose statistics about the Change Page Attribute mechanism, which 1512 helps to determine the effectiveness of preserving large and huge 1513 page mappings when mapping protections are changed. 1514 1515config X86_MEM_ENCRYPT 1516 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1517 select DYNAMIC_PHYSICAL_MASK 1518 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS 1519 def_bool n 1520 1521config AMD_MEM_ENCRYPT 1522 bool "AMD Secure Memory Encryption (SME) support" 1523 depends on X86_64 && CPU_SUP_AMD 1524 select DMA_COHERENT_POOL 1525 select ARCH_USE_MEMREMAP_PROT 1526 select INSTRUCTION_DECODER 1527 select ARCH_HAS_CC_PLATFORM 1528 select X86_MEM_ENCRYPT 1529 help 1530 Say yes to enable support for the encryption of system memory. 1531 This requires an AMD processor that supports Secure Memory 1532 Encryption (SME). 1533 1534config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1535 bool "Activate AMD Secure Memory Encryption (SME) by default" 1536 depends on AMD_MEM_ENCRYPT 1537 help 1538 Say yes to have system memory encrypted by default if running on 1539 an AMD processor that supports Secure Memory Encryption (SME). 1540 1541 If set to Y, then the encryption of system memory can be 1542 deactivated with the mem_encrypt=off command line option. 1543 1544 If set to N, then the encryption of system memory can be 1545 activated with the mem_encrypt=on command line option. 1546 1547# Common NUMA Features 1548config NUMA 1549 bool "NUMA Memory Allocation and Scheduler Support" 1550 depends on SMP 1551 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1552 default y if X86_BIGSMP 1553 select USE_PERCPU_NUMA_NODE_ID 1554 help 1555 Enable NUMA (Non-Uniform Memory Access) support. 1556 1557 The kernel will try to allocate memory used by a CPU on the 1558 local memory controller of the CPU and add some more 1559 NUMA awareness to the kernel. 1560 1561 For 64-bit this is recommended if the system is Intel Core i7 1562 (or later), AMD Opteron, or EM64T NUMA. 1563 1564 For 32-bit this is only needed if you boot a 32-bit 1565 kernel on a 64-bit NUMA platform. 1566 1567 Otherwise, you should say N. 1568 1569config AMD_NUMA 1570 def_bool y 1571 prompt "Old style AMD Opteron NUMA detection" 1572 depends on X86_64 && NUMA && PCI 1573 help 1574 Enable AMD NUMA node topology detection. You should say Y here if 1575 you have a multi processor AMD system. This uses an old method to 1576 read the NUMA configuration directly from the builtin Northbridge 1577 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1578 which also takes priority if both are compiled in. 1579 1580config X86_64_ACPI_NUMA 1581 def_bool y 1582 prompt "ACPI NUMA detection" 1583 depends on X86_64 && NUMA && ACPI && PCI 1584 select ACPI_NUMA 1585 help 1586 Enable ACPI SRAT based node topology detection. 1587 1588config NUMA_EMU 1589 bool "NUMA emulation" 1590 depends on NUMA 1591 help 1592 Enable NUMA emulation. A flat machine will be split 1593 into virtual nodes when booted with "numa=fake=N", where N is the 1594 number of nodes. This is only useful for debugging. 1595 1596config NODES_SHIFT 1597 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1598 range 1 10 1599 default "10" if MAXSMP 1600 default "6" if X86_64 1601 default "3" 1602 depends on NUMA 1603 help 1604 Specify the maximum number of NUMA Nodes available on the target 1605 system. Increases memory reserved to accommodate various tables. 1606 1607config ARCH_FLATMEM_ENABLE 1608 def_bool y 1609 depends on X86_32 && !NUMA 1610 1611config ARCH_SPARSEMEM_ENABLE 1612 def_bool y 1613 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1614 select SPARSEMEM_STATIC if X86_32 1615 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1616 1617config ARCH_SPARSEMEM_DEFAULT 1618 def_bool X86_64 || (NUMA && X86_32) 1619 1620config ARCH_SELECT_MEMORY_MODEL 1621 def_bool y 1622 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1623 1624config ARCH_MEMORY_PROBE 1625 bool "Enable sysfs memory/probe interface" 1626 depends on MEMORY_HOTPLUG 1627 help 1628 This option enables a sysfs memory/probe interface for testing. 1629 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1630 If you are unsure how to answer this question, answer N. 1631 1632config ARCH_PROC_KCORE_TEXT 1633 def_bool y 1634 depends on X86_64 && PROC_KCORE 1635 1636config ILLEGAL_POINTER_VALUE 1637 hex 1638 default 0 if X86_32 1639 default 0xdead000000000000 if X86_64 1640 1641config X86_PMEM_LEGACY_DEVICE 1642 bool 1643 1644config X86_PMEM_LEGACY 1645 tristate "Support non-standard NVDIMMs and ADR protected memory" 1646 depends on PHYS_ADDR_T_64BIT 1647 depends on BLK_DEV 1648 select X86_PMEM_LEGACY_DEVICE 1649 select NUMA_KEEP_MEMINFO if NUMA 1650 select LIBNVDIMM 1651 help 1652 Treat memory marked using the non-standard e820 type of 12 as used 1653 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1654 The kernel will offer these regions to the 'pmem' driver so 1655 they can be used for persistent storage. 1656 1657 Say Y if unsure. 1658 1659config HIGHPTE 1660 bool "Allocate 3rd-level pagetables from highmem" 1661 depends on HIGHMEM 1662 help 1663 The VM uses one page table entry for each page of physical memory. 1664 For systems with a lot of RAM, this can be wasteful of precious 1665 low memory. Setting this option will put user-space page table 1666 entries in high memory. 1667 1668config X86_CHECK_BIOS_CORRUPTION 1669 bool "Check for low memory corruption" 1670 help 1671 Periodically check for memory corruption in low memory, which 1672 is suspected to be caused by BIOS. Even when enabled in the 1673 configuration, it is disabled at runtime. Enable it by 1674 setting "memory_corruption_check=1" on the kernel command 1675 line. By default it scans the low 64k of memory every 60 1676 seconds; see the memory_corruption_check_size and 1677 memory_corruption_check_period parameters in 1678 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1679 1680 When enabled with the default parameters, this option has 1681 almost no overhead, as it reserves a relatively small amount 1682 of memory and scans it infrequently. It both detects corruption 1683 and prevents it from affecting the running system. 1684 1685 It is, however, intended as a diagnostic tool; if repeatable 1686 BIOS-originated corruption always affects the same memory, 1687 you can use memmap= to prevent the kernel from using that 1688 memory. 1689 1690config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1691 bool "Set the default setting of memory_corruption_check" 1692 depends on X86_CHECK_BIOS_CORRUPTION 1693 default y 1694 help 1695 Set whether the default state of memory_corruption_check is 1696 on or off. 1697 1698config MATH_EMULATION 1699 bool 1700 depends on MODIFY_LDT_SYSCALL 1701 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1702 help 1703 Linux can emulate a math coprocessor (used for floating point 1704 operations) if you don't have one. 486DX and Pentium processors have 1705 a math coprocessor built in, 486SX and 386 do not, unless you added 1706 a 487DX or 387, respectively. (The messages during boot time can 1707 give you some hints here ["man dmesg"].) Everyone needs either a 1708 coprocessor or this emulation. 1709 1710 If you don't have a math coprocessor, you need to say Y here; if you 1711 say Y here even though you have a coprocessor, the coprocessor will 1712 be used nevertheless. (This behavior can be changed with the kernel 1713 command line option "no387", which comes handy if your coprocessor 1714 is broken. Try "man bootparam" or see the documentation of your boot 1715 loader (lilo or loadlin) about how to pass options to the kernel at 1716 boot time.) This means that it is a good idea to say Y here if you 1717 intend to use this kernel on different machines. 1718 1719 More information about the internals of the Linux math coprocessor 1720 emulation can be found in <file:arch/x86/math-emu/README>. 1721 1722 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1723 kernel, it won't hurt. 1724 1725config MTRR 1726 def_bool y 1727 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1728 help 1729 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1730 the Memory Type Range Registers (MTRRs) may be used to control 1731 processor access to memory ranges. This is most useful if you have 1732 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1733 allows bus write transfers to be combined into a larger transfer 1734 before bursting over the PCI/AGP bus. This can increase performance 1735 of image write operations 2.5 times or more. Saying Y here creates a 1736 /proc/mtrr file which may be used to manipulate your processor's 1737 MTRRs. Typically the X server should use this. 1738 1739 This code has a reasonably generic interface so that similar 1740 control registers on other processors can be easily supported 1741 as well: 1742 1743 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1744 Registers (ARRs) which provide a similar functionality to MTRRs. For 1745 these, the ARRs are used to emulate the MTRRs. 1746 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1747 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1748 write-combining. All of these processors are supported by this code 1749 and it makes sense to say Y here if you have one of them. 1750 1751 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1752 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1753 can lead to all sorts of problems, so it's good to say Y here. 1754 1755 You can safely say Y even if your machine doesn't have MTRRs, you'll 1756 just add about 9 KB to your kernel. 1757 1758 See <file:Documentation/x86/mtrr.rst> for more information. 1759 1760config MTRR_SANITIZER 1761 def_bool y 1762 prompt "MTRR cleanup support" 1763 depends on MTRR 1764 help 1765 Convert MTRR layout from continuous to discrete, so X drivers can 1766 add writeback entries. 1767 1768 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1769 The largest mtrr entry size for a continuous block can be set with 1770 mtrr_chunk_size. 1771 1772 If unsure, say Y. 1773 1774config MTRR_SANITIZER_ENABLE_DEFAULT 1775 int "MTRR cleanup enable value (0-1)" 1776 range 0 1 1777 default "0" 1778 depends on MTRR_SANITIZER 1779 help 1780 Enable mtrr cleanup default value 1781 1782config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1783 int "MTRR cleanup spare reg num (0-7)" 1784 range 0 7 1785 default "1" 1786 depends on MTRR_SANITIZER 1787 help 1788 mtrr cleanup spare entries default, it can be changed via 1789 mtrr_spare_reg_nr=N on the kernel command line. 1790 1791config X86_PAT 1792 def_bool y 1793 prompt "x86 PAT support" if EXPERT 1794 depends on MTRR 1795 help 1796 Use PAT attributes to setup page level cache control. 1797 1798 PATs are the modern equivalents of MTRRs and are much more 1799 flexible than MTRRs. 1800 1801 Say N here if you see bootup problems (boot crash, boot hang, 1802 spontaneous reboots) or a non-working video driver. 1803 1804 If unsure, say Y. 1805 1806config ARCH_USES_PG_UNCACHED 1807 def_bool y 1808 depends on X86_PAT 1809 1810config ARCH_RANDOM 1811 def_bool y 1812 prompt "x86 architectural random number generator" if EXPERT 1813 help 1814 Enable the x86 architectural RDRAND instruction 1815 (Intel Bull Mountain technology) to generate random numbers. 1816 If supported, this is a high bandwidth, cryptographically 1817 secure hardware random number generator. 1818 1819config X86_SMAP 1820 def_bool y 1821 prompt "Supervisor Mode Access Prevention" if EXPERT 1822 help 1823 Supervisor Mode Access Prevention (SMAP) is a security 1824 feature in newer Intel processors. There is a small 1825 performance cost if this enabled and turned on; there is 1826 also a small increase in the kernel size if this is enabled. 1827 1828 If unsure, say Y. 1829 1830config X86_UMIP 1831 def_bool y 1832 prompt "User Mode Instruction Prevention" if EXPERT 1833 help 1834 User Mode Instruction Prevention (UMIP) is a security feature in 1835 some x86 processors. If enabled, a general protection fault is 1836 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1837 executed in user mode. These instructions unnecessarily expose 1838 information about the hardware state. 1839 1840 The vast majority of applications do not use these instructions. 1841 For the very few that do, software emulation is provided in 1842 specific cases in protected and virtual-8086 modes. Emulated 1843 results are dummy. 1844 1845config CC_HAS_IBT 1846 # GCC >= 9 and binutils >= 2.29 1847 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1848 # Clang/LLVM >= 14 1849 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1850 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1851 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1852 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1853 $(as-instr,endbr64) 1854 1855config X86_KERNEL_IBT 1856 prompt "Indirect Branch Tracking" 1857 bool 1858 depends on X86_64 && CC_HAS_IBT && STACK_VALIDATION 1859 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1860 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1861 help 1862 Build the kernel with support for Indirect Branch Tracking, a 1863 hardware support course-grain forward-edge Control Flow Integrity 1864 protection. It enforces that all indirect calls must land on 1865 an ENDBR instruction, as such, the compiler will instrument the 1866 code with them to make this happen. 1867 1868 In addition to building the kernel with IBT, seal all functions that 1869 are not indirect call targets, avoiding them ever becoming one. 1870 1871 This requires LTO like objtool runs and will slow down the build. It 1872 does significantly reduce the number of ENDBR instructions in the 1873 kernel image. 1874 1875config X86_INTEL_MEMORY_PROTECTION_KEYS 1876 prompt "Memory Protection Keys" 1877 def_bool y 1878 # Note: only available in 64-bit mode 1879 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1880 select ARCH_USES_HIGH_VMA_FLAGS 1881 select ARCH_HAS_PKEYS 1882 help 1883 Memory Protection Keys provides a mechanism for enforcing 1884 page-based protections, but without requiring modification of the 1885 page tables when an application changes protection domains. 1886 1887 For details, see Documentation/core-api/protection-keys.rst 1888 1889 If unsure, say y. 1890 1891choice 1892 prompt "TSX enable mode" 1893 depends on CPU_SUP_INTEL 1894 default X86_INTEL_TSX_MODE_OFF 1895 help 1896 Intel's TSX (Transactional Synchronization Extensions) feature 1897 allows to optimize locking protocols through lock elision which 1898 can lead to a noticeable performance boost. 1899 1900 On the other hand it has been shown that TSX can be exploited 1901 to form side channel attacks (e.g. TAA) and chances are there 1902 will be more of those attacks discovered in the future. 1903 1904 Therefore TSX is not enabled by default (aka tsx=off). An admin 1905 might override this decision by tsx=on the command line parameter. 1906 Even with TSX enabled, the kernel will attempt to enable the best 1907 possible TAA mitigation setting depending on the microcode available 1908 for the particular machine. 1909 1910 This option allows to set the default tsx mode between tsx=on, =off 1911 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1912 details. 1913 1914 Say off if not sure, auto if TSX is in use but it should be used on safe 1915 platforms or on if TSX is in use and the security aspect of tsx is not 1916 relevant. 1917 1918config X86_INTEL_TSX_MODE_OFF 1919 bool "off" 1920 help 1921 TSX is disabled if possible - equals to tsx=off command line parameter. 1922 1923config X86_INTEL_TSX_MODE_ON 1924 bool "on" 1925 help 1926 TSX is always enabled on TSX capable HW - equals the tsx=on command 1927 line parameter. 1928 1929config X86_INTEL_TSX_MODE_AUTO 1930 bool "auto" 1931 help 1932 TSX is enabled on TSX capable HW that is believed to be safe against 1933 side channel attacks- equals the tsx=auto command line parameter. 1934endchoice 1935 1936config X86_SGX 1937 bool "Software Guard eXtensions (SGX)" 1938 depends on X86_64 && CPU_SUP_INTEL 1939 depends on CRYPTO=y 1940 depends on CRYPTO_SHA256=y 1941 select SRCU 1942 select MMU_NOTIFIER 1943 select NUMA_KEEP_MEMINFO if NUMA 1944 select XARRAY_MULTI 1945 help 1946 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1947 that can be used by applications to set aside private regions of code 1948 and data, referred to as enclaves. An enclave's private memory can 1949 only be accessed by code running within the enclave. Accesses from 1950 outside the enclave, including other enclaves, are disallowed by 1951 hardware. 1952 1953 If unsure, say N. 1954 1955config EFI 1956 bool "EFI runtime service support" 1957 depends on ACPI 1958 select UCS2_STRING 1959 select EFI_RUNTIME_WRAPPERS 1960 select ARCH_USE_MEMREMAP_PROT 1961 help 1962 This enables the kernel to use EFI runtime services that are 1963 available (such as the EFI variable services). 1964 1965 This option is only useful on systems that have EFI firmware. 1966 In addition, you should use the latest ELILO loader available 1967 at <http://elilo.sourceforge.net> in order to take advantage 1968 of EFI runtime services. However, even with this option, the 1969 resultant kernel should continue to boot on existing non-EFI 1970 platforms. 1971 1972config EFI_STUB 1973 bool "EFI stub support" 1974 depends on EFI 1975 depends on $(cc-option,-mabi=ms) || X86_32 1976 select RELOCATABLE 1977 help 1978 This kernel feature allows a bzImage to be loaded directly 1979 by EFI firmware without the use of a bootloader. 1980 1981 See Documentation/admin-guide/efi-stub.rst for more information. 1982 1983config EFI_MIXED 1984 bool "EFI mixed-mode support" 1985 depends on EFI_STUB && X86_64 1986 help 1987 Enabling this feature allows a 64-bit kernel to be booted 1988 on a 32-bit firmware, provided that your CPU supports 64-bit 1989 mode. 1990 1991 Note that it is not possible to boot a mixed-mode enabled 1992 kernel via the EFI boot stub - a bootloader that supports 1993 the EFI handover protocol must be used. 1994 1995 If unsure, say N. 1996 1997source "kernel/Kconfig.hz" 1998 1999config KEXEC 2000 bool "kexec system call" 2001 select KEXEC_CORE 2002 help 2003 kexec is a system call that implements the ability to shutdown your 2004 current kernel, and to start another kernel. It is like a reboot 2005 but it is independent of the system firmware. And like a reboot 2006 you can start any kernel with it, not just Linux. 2007 2008 The name comes from the similarity to the exec system call. 2009 2010 It is an ongoing process to be certain the hardware in a machine 2011 is properly shutdown, so do not be surprised if this code does not 2012 initially work for you. As of this writing the exact hardware 2013 interface is strongly in flux, so no good recommendation can be 2014 made. 2015 2016config KEXEC_FILE 2017 bool "kexec file based system call" 2018 select KEXEC_CORE 2019 select BUILD_BIN2C 2020 depends on X86_64 2021 depends on CRYPTO=y 2022 depends on CRYPTO_SHA256=y 2023 help 2024 This is new version of kexec system call. This system call is 2025 file based and takes file descriptors as system call argument 2026 for kernel and initramfs as opposed to list of segments as 2027 accepted by previous system call. 2028 2029config ARCH_HAS_KEXEC_PURGATORY 2030 def_bool KEXEC_FILE 2031 2032config KEXEC_SIG 2033 bool "Verify kernel signature during kexec_file_load() syscall" 2034 depends on KEXEC_FILE 2035 help 2036 2037 This option makes the kexec_file_load() syscall check for a valid 2038 signature of the kernel image. The image can still be loaded without 2039 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2040 there's a signature that we can check, then it must be valid. 2041 2042 In addition to this option, you need to enable signature 2043 verification for the corresponding kernel image type being 2044 loaded in order for this to work. 2045 2046config KEXEC_SIG_FORCE 2047 bool "Require a valid signature in kexec_file_load() syscall" 2048 depends on KEXEC_SIG 2049 help 2050 This option makes kernel signature verification mandatory for 2051 the kexec_file_load() syscall. 2052 2053config KEXEC_BZIMAGE_VERIFY_SIG 2054 bool "Enable bzImage signature verification support" 2055 depends on KEXEC_SIG 2056 depends on SIGNED_PE_FILE_VERIFICATION 2057 select SYSTEM_TRUSTED_KEYRING 2058 help 2059 Enable bzImage signature verification support. 2060 2061config CRASH_DUMP 2062 bool "kernel crash dumps" 2063 depends on X86_64 || (X86_32 && HIGHMEM) 2064 help 2065 Generate crash dump after being started by kexec. 2066 This should be normally only set in special crash dump kernels 2067 which are loaded in the main kernel with kexec-tools into 2068 a specially reserved region and then later executed after 2069 a crash by kdump/kexec. The crash dump kernel must be compiled 2070 to a memory address not used by the main kernel or BIOS using 2071 PHYSICAL_START, or it must be built as a relocatable image 2072 (CONFIG_RELOCATABLE=y). 2073 For more details see Documentation/admin-guide/kdump/kdump.rst 2074 2075config KEXEC_JUMP 2076 bool "kexec jump" 2077 depends on KEXEC && HIBERNATION 2078 help 2079 Jump between original kernel and kexeced kernel and invoke 2080 code in physical address mode via KEXEC 2081 2082config PHYSICAL_START 2083 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2084 default "0x1000000" 2085 help 2086 This gives the physical address where the kernel is loaded. 2087 2088 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2089 bzImage will decompress itself to above physical address and 2090 run from there. Otherwise, bzImage will run from the address where 2091 it has been loaded by the boot loader and will ignore above physical 2092 address. 2093 2094 In normal kdump cases one does not have to set/change this option 2095 as now bzImage can be compiled as a completely relocatable image 2096 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2097 address. This option is mainly useful for the folks who don't want 2098 to use a bzImage for capturing the crash dump and want to use a 2099 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2100 to be specifically compiled to run from a specific memory area 2101 (normally a reserved region) and this option comes handy. 2102 2103 So if you are using bzImage for capturing the crash dump, 2104 leave the value here unchanged to 0x1000000 and set 2105 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2106 for capturing the crash dump change this value to start of 2107 the reserved region. In other words, it can be set based on 2108 the "X" value as specified in the "crashkernel=YM@XM" 2109 command line boot parameter passed to the panic-ed 2110 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2111 for more details about crash dumps. 2112 2113 Usage of bzImage for capturing the crash dump is recommended as 2114 one does not have to build two kernels. Same kernel can be used 2115 as production kernel and capture kernel. Above option should have 2116 gone away after relocatable bzImage support is introduced. But it 2117 is present because there are users out there who continue to use 2118 vmlinux for dump capture. This option should go away down the 2119 line. 2120 2121 Don't change this unless you know what you are doing. 2122 2123config RELOCATABLE 2124 bool "Build a relocatable kernel" 2125 default y 2126 help 2127 This builds a kernel image that retains relocation information 2128 so it can be loaded someplace besides the default 1MB. 2129 The relocations tend to make the kernel binary about 10% larger, 2130 but are discarded at runtime. 2131 2132 One use is for the kexec on panic case where the recovery kernel 2133 must live at a different physical address than the primary 2134 kernel. 2135 2136 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2137 it has been loaded at and the compile time physical address 2138 (CONFIG_PHYSICAL_START) is used as the minimum location. 2139 2140config RANDOMIZE_BASE 2141 bool "Randomize the address of the kernel image (KASLR)" 2142 depends on RELOCATABLE 2143 default y 2144 help 2145 In support of Kernel Address Space Layout Randomization (KASLR), 2146 this randomizes the physical address at which the kernel image 2147 is decompressed and the virtual address where the kernel 2148 image is mapped, as a security feature that deters exploit 2149 attempts relying on knowledge of the location of kernel 2150 code internals. 2151 2152 On 64-bit, the kernel physical and virtual addresses are 2153 randomized separately. The physical address will be anywhere 2154 between 16MB and the top of physical memory (up to 64TB). The 2155 virtual address will be randomized from 16MB up to 1GB (9 bits 2156 of entropy). Note that this also reduces the memory space 2157 available to kernel modules from 1.5GB to 1GB. 2158 2159 On 32-bit, the kernel physical and virtual addresses are 2160 randomized together. They will be randomized from 16MB up to 2161 512MB (8 bits of entropy). 2162 2163 Entropy is generated using the RDRAND instruction if it is 2164 supported. If RDTSC is supported, its value is mixed into 2165 the entropy pool as well. If neither RDRAND nor RDTSC are 2166 supported, then entropy is read from the i8254 timer. The 2167 usable entropy is limited by the kernel being built using 2168 2GB addressing, and that PHYSICAL_ALIGN must be at a 2169 minimum of 2MB. As a result, only 10 bits of entropy are 2170 theoretically possible, but the implementations are further 2171 limited due to memory layouts. 2172 2173 If unsure, say Y. 2174 2175# Relocation on x86 needs some additional build support 2176config X86_NEED_RELOCS 2177 def_bool y 2178 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2179 2180config PHYSICAL_ALIGN 2181 hex "Alignment value to which kernel should be aligned" 2182 default "0x200000" 2183 range 0x2000 0x1000000 if X86_32 2184 range 0x200000 0x1000000 if X86_64 2185 help 2186 This value puts the alignment restrictions on physical address 2187 where kernel is loaded and run from. Kernel is compiled for an 2188 address which meets above alignment restriction. 2189 2190 If bootloader loads the kernel at a non-aligned address and 2191 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2192 address aligned to above value and run from there. 2193 2194 If bootloader loads the kernel at a non-aligned address and 2195 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2196 load address and decompress itself to the address it has been 2197 compiled for and run from there. The address for which kernel is 2198 compiled already meets above alignment restrictions. Hence the 2199 end result is that kernel runs from a physical address meeting 2200 above alignment restrictions. 2201 2202 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2203 this value must be a multiple of 0x200000. 2204 2205 Don't change this unless you know what you are doing. 2206 2207config DYNAMIC_MEMORY_LAYOUT 2208 bool 2209 help 2210 This option makes base addresses of vmalloc and vmemmap as well as 2211 __PAGE_OFFSET movable during boot. 2212 2213config RANDOMIZE_MEMORY 2214 bool "Randomize the kernel memory sections" 2215 depends on X86_64 2216 depends on RANDOMIZE_BASE 2217 select DYNAMIC_MEMORY_LAYOUT 2218 default RANDOMIZE_BASE 2219 help 2220 Randomizes the base virtual address of kernel memory sections 2221 (physical memory mapping, vmalloc & vmemmap). This security feature 2222 makes exploits relying on predictable memory locations less reliable. 2223 2224 The order of allocations remains unchanged. Entropy is generated in 2225 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2226 configuration have in average 30,000 different possible virtual 2227 addresses for each memory section. 2228 2229 If unsure, say Y. 2230 2231config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2232 hex "Physical memory mapping padding" if EXPERT 2233 depends on RANDOMIZE_MEMORY 2234 default "0xa" if MEMORY_HOTPLUG 2235 default "0x0" 2236 range 0x1 0x40 if MEMORY_HOTPLUG 2237 range 0x0 0x40 2238 help 2239 Define the padding in terabytes added to the existing physical 2240 memory size during kernel memory randomization. It is useful 2241 for memory hotplug support but reduces the entropy available for 2242 address randomization. 2243 2244 If unsure, leave at the default value. 2245 2246config HOTPLUG_CPU 2247 def_bool y 2248 depends on SMP 2249 2250config BOOTPARAM_HOTPLUG_CPU0 2251 bool "Set default setting of cpu0_hotpluggable" 2252 depends on HOTPLUG_CPU 2253 help 2254 Set whether default state of cpu0_hotpluggable is on or off. 2255 2256 Say Y here to enable CPU0 hotplug by default. If this switch 2257 is turned on, there is no need to give cpu0_hotplug kernel 2258 parameter and the CPU0 hotplug feature is enabled by default. 2259 2260 Please note: there are two known CPU0 dependencies if you want 2261 to enable the CPU0 hotplug feature either by this switch or by 2262 cpu0_hotplug kernel parameter. 2263 2264 First, resume from hibernate or suspend always starts from CPU0. 2265 So hibernate and suspend are prevented if CPU0 is offline. 2266 2267 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2268 offline if any interrupt can not migrate out of CPU0. There may 2269 be other CPU0 dependencies. 2270 2271 Please make sure the dependencies are under your control before 2272 you enable this feature. 2273 2274 Say N if you don't want to enable CPU0 hotplug feature by default. 2275 You still can enable the CPU0 hotplug feature at boot by kernel 2276 parameter cpu0_hotplug. 2277 2278config DEBUG_HOTPLUG_CPU0 2279 def_bool n 2280 prompt "Debug CPU0 hotplug" 2281 depends on HOTPLUG_CPU 2282 help 2283 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2284 soon as possible and boots up userspace with CPU0 offlined. User 2285 can online CPU0 back after boot time. 2286 2287 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2288 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2289 compilation or giving cpu0_hotplug kernel parameter at boot. 2290 2291 If unsure, say N. 2292 2293config COMPAT_VDSO 2294 def_bool n 2295 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2296 depends on COMPAT_32 2297 help 2298 Certain buggy versions of glibc will crash if they are 2299 presented with a 32-bit vDSO that is not mapped at the address 2300 indicated in its segment table. 2301 2302 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2303 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2304 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2305 the only released version with the bug, but OpenSUSE 9 2306 contains a buggy "glibc 2.3.2". 2307 2308 The symptom of the bug is that everything crashes on startup, saying: 2309 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2310 2311 Saying Y here changes the default value of the vdso32 boot 2312 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2313 This works around the glibc bug but hurts performance. 2314 2315 If unsure, say N: if you are compiling your own kernel, you 2316 are unlikely to be using a buggy version of glibc. 2317 2318choice 2319 prompt "vsyscall table for legacy applications" 2320 depends on X86_64 2321 default LEGACY_VSYSCALL_XONLY 2322 help 2323 Legacy user code that does not know how to find the vDSO expects 2324 to be able to issue three syscalls by calling fixed addresses in 2325 kernel space. Since this location is not randomized with ASLR, 2326 it can be used to assist security vulnerability exploitation. 2327 2328 This setting can be changed at boot time via the kernel command 2329 line parameter vsyscall=[emulate|xonly|none]. 2330 2331 On a system with recent enough glibc (2.14 or newer) and no 2332 static binaries, you can say None without a performance penalty 2333 to improve security. 2334 2335 If unsure, select "Emulate execution only". 2336 2337 config LEGACY_VSYSCALL_EMULATE 2338 bool "Full emulation" 2339 help 2340 The kernel traps and emulates calls into the fixed vsyscall 2341 address mapping. This makes the mapping non-executable, but 2342 it still contains readable known contents, which could be 2343 used in certain rare security vulnerability exploits. This 2344 configuration is recommended when using legacy userspace 2345 that still uses vsyscalls along with legacy binary 2346 instrumentation tools that require code to be readable. 2347 2348 An example of this type of legacy userspace is running 2349 Pin on an old binary that still uses vsyscalls. 2350 2351 config LEGACY_VSYSCALL_XONLY 2352 bool "Emulate execution only" 2353 help 2354 The kernel traps and emulates calls into the fixed vsyscall 2355 address mapping and does not allow reads. This 2356 configuration is recommended when userspace might use the 2357 legacy vsyscall area but support for legacy binary 2358 instrumentation of legacy code is not needed. It mitigates 2359 certain uses of the vsyscall area as an ASLR-bypassing 2360 buffer. 2361 2362 config LEGACY_VSYSCALL_NONE 2363 bool "None" 2364 help 2365 There will be no vsyscall mapping at all. This will 2366 eliminate any risk of ASLR bypass due to the vsyscall 2367 fixed address mapping. Attempts to use the vsyscalls 2368 will be reported to dmesg, so that either old or 2369 malicious userspace programs can be identified. 2370 2371endchoice 2372 2373config CMDLINE_BOOL 2374 bool "Built-in kernel command line" 2375 help 2376 Allow for specifying boot arguments to the kernel at 2377 build time. On some systems (e.g. embedded ones), it is 2378 necessary or convenient to provide some or all of the 2379 kernel boot arguments with the kernel itself (that is, 2380 to not rely on the boot loader to provide them.) 2381 2382 To compile command line arguments into the kernel, 2383 set this option to 'Y', then fill in the 2384 boot arguments in CONFIG_CMDLINE. 2385 2386 Systems with fully functional boot loaders (i.e. non-embedded) 2387 should leave this option set to 'N'. 2388 2389config CMDLINE 2390 string "Built-in kernel command string" 2391 depends on CMDLINE_BOOL 2392 default "" 2393 help 2394 Enter arguments here that should be compiled into the kernel 2395 image and used at boot time. If the boot loader provides a 2396 command line at boot time, it is appended to this string to 2397 form the full kernel command line, when the system boots. 2398 2399 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2400 change this behavior. 2401 2402 In most cases, the command line (whether built-in or provided 2403 by the boot loader) should specify the device for the root 2404 file system. 2405 2406config CMDLINE_OVERRIDE 2407 bool "Built-in command line overrides boot loader arguments" 2408 depends on CMDLINE_BOOL && CMDLINE != "" 2409 help 2410 Set this option to 'Y' to have the kernel ignore the boot loader 2411 command line, and use ONLY the built-in command line. 2412 2413 This is used to work around broken boot loaders. This should 2414 be set to 'N' under normal conditions. 2415 2416config MODIFY_LDT_SYSCALL 2417 bool "Enable the LDT (local descriptor table)" if EXPERT 2418 default y 2419 help 2420 Linux can allow user programs to install a per-process x86 2421 Local Descriptor Table (LDT) using the modify_ldt(2) system 2422 call. This is required to run 16-bit or segmented code such as 2423 DOSEMU or some Wine programs. It is also used by some very old 2424 threading libraries. 2425 2426 Enabling this feature adds a small amount of overhead to 2427 context switches and increases the low-level kernel attack 2428 surface. Disabling it removes the modify_ldt(2) system call. 2429 2430 Saying 'N' here may make sense for embedded or server kernels. 2431 2432config STRICT_SIGALTSTACK_SIZE 2433 bool "Enforce strict size checking for sigaltstack" 2434 depends on DYNAMIC_SIGFRAME 2435 help 2436 For historical reasons MINSIGSTKSZ is a constant which became 2437 already too small with AVX512 support. Add a mechanism to 2438 enforce strict checking of the sigaltstack size against the 2439 real size of the FPU frame. This option enables the check 2440 by default. It can also be controlled via the kernel command 2441 line option 'strict_sas_size' independent of this config 2442 switch. Enabling it might break existing applications which 2443 allocate a too small sigaltstack but 'work' because they 2444 never get a signal delivered. 2445 2446 Say 'N' unless you want to really enforce this check. 2447 2448source "kernel/livepatch/Kconfig" 2449 2450endmenu 2451 2452config ARCH_HAS_ADD_PAGES 2453 def_bool y 2454 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2455 2456config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2457 def_bool y 2458 2459menu "Power management and ACPI options" 2460 2461config ARCH_HIBERNATION_HEADER 2462 def_bool y 2463 depends on HIBERNATION 2464 2465source "kernel/power/Kconfig" 2466 2467source "drivers/acpi/Kconfig" 2468 2469config X86_APM_BOOT 2470 def_bool y 2471 depends on APM 2472 2473menuconfig APM 2474 tristate "APM (Advanced Power Management) BIOS support" 2475 depends on X86_32 && PM_SLEEP 2476 help 2477 APM is a BIOS specification for saving power using several different 2478 techniques. This is mostly useful for battery powered laptops with 2479 APM compliant BIOSes. If you say Y here, the system time will be 2480 reset after a RESUME operation, the /proc/apm device will provide 2481 battery status information, and user-space programs will receive 2482 notification of APM "events" (e.g. battery status change). 2483 2484 If you select "Y" here, you can disable actual use of the APM 2485 BIOS by passing the "apm=off" option to the kernel at boot time. 2486 2487 Note that the APM support is almost completely disabled for 2488 machines with more than one CPU. 2489 2490 In order to use APM, you will need supporting software. For location 2491 and more information, read <file:Documentation/power/apm-acpi.rst> 2492 and the Battery Powered Linux mini-HOWTO, available from 2493 <http://www.tldp.org/docs.html#howto>. 2494 2495 This driver does not spin down disk drives (see the hdparm(8) 2496 manpage ("man 8 hdparm") for that), and it doesn't turn off 2497 VESA-compliant "green" monitors. 2498 2499 This driver does not support the TI 4000M TravelMate and the ACER 2500 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2501 desktop machines also don't have compliant BIOSes, and this driver 2502 may cause those machines to panic during the boot phase. 2503 2504 Generally, if you don't have a battery in your machine, there isn't 2505 much point in using this driver and you should say N. If you get 2506 random kernel OOPSes or reboots that don't seem to be related to 2507 anything, try disabling/enabling this option (or disabling/enabling 2508 APM in your BIOS). 2509 2510 Some other things you should try when experiencing seemingly random, 2511 "weird" problems: 2512 2513 1) make sure that you have enough swap space and that it is 2514 enabled. 2515 2) pass the "no-hlt" option to the kernel 2516 3) switch on floating point emulation in the kernel and pass 2517 the "no387" option to the kernel 2518 4) pass the "floppy=nodma" option to the kernel 2519 5) pass the "mem=4M" option to the kernel (thereby disabling 2520 all but the first 4 MB of RAM) 2521 6) make sure that the CPU is not over clocked. 2522 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2523 8) disable the cache from your BIOS settings 2524 9) install a fan for the video card or exchange video RAM 2525 10) install a better fan for the CPU 2526 11) exchange RAM chips 2527 12) exchange the motherboard. 2528 2529 To compile this driver as a module, choose M here: the 2530 module will be called apm. 2531 2532if APM 2533 2534config APM_IGNORE_USER_SUSPEND 2535 bool "Ignore USER SUSPEND" 2536 help 2537 This option will ignore USER SUSPEND requests. On machines with a 2538 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2539 series notebooks, it is necessary to say Y because of a BIOS bug. 2540 2541config APM_DO_ENABLE 2542 bool "Enable PM at boot time" 2543 help 2544 Enable APM features at boot time. From page 36 of the APM BIOS 2545 specification: "When disabled, the APM BIOS does not automatically 2546 power manage devices, enter the Standby State, enter the Suspend 2547 State, or take power saving steps in response to CPU Idle calls." 2548 This driver will make CPU Idle calls when Linux is idle (unless this 2549 feature is turned off -- see "Do CPU IDLE calls", below). This 2550 should always save battery power, but more complicated APM features 2551 will be dependent on your BIOS implementation. You may need to turn 2552 this option off if your computer hangs at boot time when using APM 2553 support, or if it beeps continuously instead of suspending. Turn 2554 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2555 T400CDT. This is off by default since most machines do fine without 2556 this feature. 2557 2558config APM_CPU_IDLE 2559 depends on CPU_IDLE 2560 bool "Make CPU Idle calls when idle" 2561 help 2562 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2563 On some machines, this can activate improved power savings, such as 2564 a slowed CPU clock rate, when the machine is idle. These idle calls 2565 are made after the idle loop has run for some length of time (e.g., 2566 333 mS). On some machines, this will cause a hang at boot time or 2567 whenever the CPU becomes idle. (On machines with more than one CPU, 2568 this option does nothing.) 2569 2570config APM_DISPLAY_BLANK 2571 bool "Enable console blanking using APM" 2572 help 2573 Enable console blanking using the APM. Some laptops can use this to 2574 turn off the LCD backlight when the screen blanker of the Linux 2575 virtual console blanks the screen. Note that this is only used by 2576 the virtual console screen blanker, and won't turn off the backlight 2577 when using the X Window system. This also doesn't have anything to 2578 do with your VESA-compliant power-saving monitor. Further, this 2579 option doesn't work for all laptops -- it might not turn off your 2580 backlight at all, or it might print a lot of errors to the console, 2581 especially if you are using gpm. 2582 2583config APM_ALLOW_INTS 2584 bool "Allow interrupts during APM BIOS calls" 2585 help 2586 Normally we disable external interrupts while we are making calls to 2587 the APM BIOS as a measure to lessen the effects of a badly behaving 2588 BIOS implementation. The BIOS should reenable interrupts if it 2589 needs to. Unfortunately, some BIOSes do not -- especially those in 2590 many of the newer IBM Thinkpads. If you experience hangs when you 2591 suspend, try setting this to Y. Otherwise, say N. 2592 2593endif # APM 2594 2595source "drivers/cpufreq/Kconfig" 2596 2597source "drivers/cpuidle/Kconfig" 2598 2599source "drivers/idle/Kconfig" 2600 2601endmenu 2602 2603 2604menu "Bus options (PCI etc.)" 2605 2606choice 2607 prompt "PCI access mode" 2608 depends on X86_32 && PCI 2609 default PCI_GOANY 2610 help 2611 On PCI systems, the BIOS can be used to detect the PCI devices and 2612 determine their configuration. However, some old PCI motherboards 2613 have BIOS bugs and may crash if this is done. Also, some embedded 2614 PCI-based systems don't have any BIOS at all. Linux can also try to 2615 detect the PCI hardware directly without using the BIOS. 2616 2617 With this option, you can specify how Linux should detect the 2618 PCI devices. If you choose "BIOS", the BIOS will be used, 2619 if you choose "Direct", the BIOS won't be used, and if you 2620 choose "MMConfig", then PCI Express MMCONFIG will be used. 2621 If you choose "Any", the kernel will try MMCONFIG, then the 2622 direct access method and falls back to the BIOS if that doesn't 2623 work. If unsure, go with the default, which is "Any". 2624 2625config PCI_GOBIOS 2626 bool "BIOS" 2627 2628config PCI_GOMMCONFIG 2629 bool "MMConfig" 2630 2631config PCI_GODIRECT 2632 bool "Direct" 2633 2634config PCI_GOOLPC 2635 bool "OLPC XO-1" 2636 depends on OLPC 2637 2638config PCI_GOANY 2639 bool "Any" 2640 2641endchoice 2642 2643config PCI_BIOS 2644 def_bool y 2645 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2646 2647# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2648config PCI_DIRECT 2649 def_bool y 2650 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2651 2652config PCI_MMCONFIG 2653 bool "Support mmconfig PCI config space access" if X86_64 2654 default y 2655 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2656 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2657 2658config PCI_OLPC 2659 def_bool y 2660 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2661 2662config PCI_XEN 2663 def_bool y 2664 depends on PCI && XEN 2665 2666config MMCONF_FAM10H 2667 def_bool y 2668 depends on X86_64 && PCI_MMCONFIG && ACPI 2669 2670config PCI_CNB20LE_QUIRK 2671 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2672 depends on PCI 2673 help 2674 Read the PCI windows out of the CNB20LE host bridge. This allows 2675 PCI hotplug to work on systems with the CNB20LE chipset which do 2676 not have ACPI. 2677 2678 There's no public spec for this chipset, and this functionality 2679 is known to be incomplete. 2680 2681 You should say N unless you know you need this. 2682 2683config ISA_BUS 2684 bool "ISA bus support on modern systems" if EXPERT 2685 help 2686 Expose ISA bus device drivers and options available for selection and 2687 configuration. Enable this option if your target machine has an ISA 2688 bus. ISA is an older system, displaced by PCI and newer bus 2689 architectures -- if your target machine is modern, it probably does 2690 not have an ISA bus. 2691 2692 If unsure, say N. 2693 2694# x86_64 have no ISA slots, but can have ISA-style DMA. 2695config ISA_DMA_API 2696 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2697 default y 2698 help 2699 Enables ISA-style DMA support for devices requiring such controllers. 2700 If unsure, say Y. 2701 2702if X86_32 2703 2704config ISA 2705 bool "ISA support" 2706 help 2707 Find out whether you have ISA slots on your motherboard. ISA is the 2708 name of a bus system, i.e. the way the CPU talks to the other stuff 2709 inside your box. Other bus systems are PCI, EISA, MicroChannel 2710 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2711 newer boards don't support it. If you have ISA, say Y, otherwise N. 2712 2713config SCx200 2714 tristate "NatSemi SCx200 support" 2715 help 2716 This provides basic support for National Semiconductor's 2717 (now AMD's) Geode processors. The driver probes for the 2718 PCI-IDs of several on-chip devices, so its a good dependency 2719 for other scx200_* drivers. 2720 2721 If compiled as a module, the driver is named scx200. 2722 2723config SCx200HR_TIMER 2724 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2725 depends on SCx200 2726 default y 2727 help 2728 This driver provides a clocksource built upon the on-chip 2729 27MHz high-resolution timer. Its also a workaround for 2730 NSC Geode SC-1100's buggy TSC, which loses time when the 2731 processor goes idle (as is done by the scheduler). The 2732 other workaround is idle=poll boot option. 2733 2734config OLPC 2735 bool "One Laptop Per Child support" 2736 depends on !X86_PAE 2737 select GPIOLIB 2738 select OF 2739 select OF_PROMTREE 2740 select IRQ_DOMAIN 2741 select OLPC_EC 2742 help 2743 Add support for detecting the unique features of the OLPC 2744 XO hardware. 2745 2746config OLPC_XO1_PM 2747 bool "OLPC XO-1 Power Management" 2748 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2749 help 2750 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2751 2752config OLPC_XO1_RTC 2753 bool "OLPC XO-1 Real Time Clock" 2754 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2755 help 2756 Add support for the XO-1 real time clock, which can be used as a 2757 programmable wakeup source. 2758 2759config OLPC_XO1_SCI 2760 bool "OLPC XO-1 SCI extras" 2761 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2762 depends on INPUT=y 2763 select POWER_SUPPLY 2764 help 2765 Add support for SCI-based features of the OLPC XO-1 laptop: 2766 - EC-driven system wakeups 2767 - Power button 2768 - Ebook switch 2769 - Lid switch 2770 - AC adapter status updates 2771 - Battery status updates 2772 2773config OLPC_XO15_SCI 2774 bool "OLPC XO-1.5 SCI extras" 2775 depends on OLPC && ACPI 2776 select POWER_SUPPLY 2777 help 2778 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2779 - EC-driven system wakeups 2780 - AC adapter status updates 2781 - Battery status updates 2782 2783config ALIX 2784 bool "PCEngines ALIX System Support (LED setup)" 2785 select GPIOLIB 2786 help 2787 This option enables system support for the PCEngines ALIX. 2788 At present this just sets up LEDs for GPIO control on 2789 ALIX2/3/6 boards. However, other system specific setup should 2790 get added here. 2791 2792 Note: You must still enable the drivers for GPIO and LED support 2793 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2794 2795 Note: You have to set alix.force=1 for boards with Award BIOS. 2796 2797config NET5501 2798 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2799 select GPIOLIB 2800 help 2801 This option enables system support for the Soekris Engineering net5501. 2802 2803config GEOS 2804 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2805 select GPIOLIB 2806 depends on DMI 2807 help 2808 This option enables system support for the Traverse Technologies GEOS. 2809 2810config TS5500 2811 bool "Technologic Systems TS-5500 platform support" 2812 depends on MELAN 2813 select CHECK_SIGNATURE 2814 select NEW_LEDS 2815 select LEDS_CLASS 2816 help 2817 This option enables system support for the Technologic Systems TS-5500. 2818 2819endif # X86_32 2820 2821config AMD_NB 2822 def_bool y 2823 depends on CPU_SUP_AMD && PCI 2824 2825endmenu 2826 2827 2828menu "Binary Emulations" 2829 2830config IA32_EMULATION 2831 bool "IA32 Emulation" 2832 depends on X86_64 2833 select ARCH_WANT_OLD_COMPAT_IPC 2834 select BINFMT_ELF 2835 select COMPAT_OLD_SIGACTION 2836 help 2837 Include code to run legacy 32-bit programs under a 2838 64-bit kernel. You should likely turn this on, unless you're 2839 100% sure that you don't have any 32-bit programs left. 2840 2841config IA32_AOUT 2842 tristate "IA32 a.out support" 2843 depends on IA32_EMULATION 2844 depends on BROKEN 2845 help 2846 Support old a.out binaries in the 32bit emulation. 2847 2848config X86_X32_ABI 2849 bool "x32 ABI for 64-bit mode" 2850 depends on X86_64 2851 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2852 # compressed debug sections to x86_x32 properly: 2853 # https://github.com/ClangBuiltLinux/linux/issues/514 2854 # https://github.com/ClangBuiltLinux/linux/issues/1141 2855 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 2856 help 2857 Include code to run binaries for the x32 native 32-bit ABI 2858 for 64-bit processors. An x32 process gets access to the 2859 full 64-bit register file and wide data path while leaving 2860 pointers at 32 bits for smaller memory footprint. 2861 2862config COMPAT_32 2863 def_bool y 2864 depends on IA32_EMULATION || X86_32 2865 select HAVE_UID16 2866 select OLD_SIGSUSPEND3 2867 2868config COMPAT 2869 def_bool y 2870 depends on IA32_EMULATION || X86_X32_ABI 2871 2872if COMPAT 2873config COMPAT_FOR_U64_ALIGNMENT 2874 def_bool y 2875 2876config SYSVIPC_COMPAT 2877 def_bool y 2878 depends on SYSVIPC 2879endif 2880 2881endmenu 2882 2883 2884config HAVE_ATOMIC_IOMAP 2885 def_bool y 2886 depends on X86_32 2887 2888source "arch/x86/kvm/Kconfig" 2889 2890source "arch/x86/Kconfig.assembler" 2891