arch/s390/Kconfig

   1 # SPDX-License-Identifier: GPL-2.0
   2 config ARCH_HAS_MEM_ENCRYPT
   3         def_bool y
   4
   5 config MMU
   6         def_bool y
   7
   8 config ZONE_DMA
   9         def_bool y
  10
  11 config CPU_BIG_ENDIAN
  12         def_bool y
  13
  14 config LOCKDEP_SUPPORT
  15         def_bool y
  16
  17 config STACKTRACE_SUPPORT
  18         def_bool y
  19
  20 config ARCH_HAS_ILOG2_U32
  21         def_bool n
  22
  23 config ARCH_HAS_ILOG2_U64
  24         def_bool n
  25
  26 config GENERIC_HWEIGHT
  27         def_bool y
  28
  29 config GENERIC_BUG
  30         def_bool y if BUG
  31
  32 config GENERIC_BUG_RELATIVE_POINTERS
  33         def_bool y
  34
  35 config GENERIC_LOCKBREAK
  36         def_bool y if PREEMPT
  37
  38 config PGSTE
  39         def_bool y if KVM
  40
  41 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
  42         def_bool y
  43
  44 config AUDIT_ARCH
  45         def_bool y
  46
  47 config NO_IOPORT_MAP
  48         def_bool y
  49
  50 config PCI_QUIRKS
  51         def_bool n
  52
  53 config ARCH_SUPPORTS_UPROBES
  54         def_bool y
  55
  56 config KASAN_SHADOW_OFFSET
  57         hex
  58         depends on KASAN
  59         default 0x18000000000000 if KASAN_S390_4_LEVEL_PAGING
  60         default 0x30000000000
  61
  62 config S390
  63         def_bool y
  64         select ARCH_BINFMT_ELF_STATE
  65         select ARCH_HAS_DEVMEM_IS_ALLOWED
  66         select ARCH_HAS_ELF_RANDOMIZE
  67         select ARCH_HAS_FORTIFY_SOURCE
  68         select ARCH_HAS_GCOV_PROFILE_ALL
  69         select ARCH_HAS_GIGANTIC_PAGE
  70         select ARCH_HAS_KCOV
  71         select ARCH_HAS_PTE_SPECIAL
  72         select ARCH_HAS_SET_MEMORY
  73         select ARCH_HAS_STRICT_KERNEL_RWX
  74         select ARCH_HAS_STRICT_MODULE_RWX
  75         select ARCH_HAS_SYSCALL_WRAPPER
  76         select ARCH_HAS_UBSAN_SANITIZE_ALL
  77         select ARCH_HAVE_NMI_SAFE_CMPXCHG
  78         select ARCH_INLINE_READ_LOCK
  79         select ARCH_INLINE_READ_LOCK_BH
  80         select ARCH_INLINE_READ_LOCK_IRQ
  81         select ARCH_INLINE_READ_LOCK_IRQSAVE
  82         select ARCH_INLINE_READ_TRYLOCK
  83         select ARCH_INLINE_READ_UNLOCK
  84         select ARCH_INLINE_READ_UNLOCK_BH
  85         select ARCH_INLINE_READ_UNLOCK_IRQ
  86         select ARCH_INLINE_READ_UNLOCK_IRQRESTORE
  87         select ARCH_INLINE_SPIN_LOCK
  88         select ARCH_INLINE_SPIN_LOCK_BH
  89         select ARCH_INLINE_SPIN_LOCK_IRQ
  90         select ARCH_INLINE_SPIN_LOCK_IRQSAVE
  91         select ARCH_INLINE_SPIN_TRYLOCK
  92         select ARCH_INLINE_SPIN_TRYLOCK_BH
  93         select ARCH_INLINE_SPIN_UNLOCK
  94         select ARCH_INLINE_SPIN_UNLOCK_BH
  95         select ARCH_INLINE_SPIN_UNLOCK_IRQ
  96         select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE
  97         select ARCH_INLINE_WRITE_LOCK
  98         select ARCH_INLINE_WRITE_LOCK_BH
  99         select ARCH_INLINE_WRITE_LOCK_IRQ
 100         select ARCH_INLINE_WRITE_LOCK_IRQSAVE
 101         select ARCH_INLINE_WRITE_TRYLOCK
 102         select ARCH_INLINE_WRITE_UNLOCK
 103         select ARCH_INLINE_WRITE_UNLOCK_BH
 104         select ARCH_INLINE_WRITE_UNLOCK_IRQ
 105         select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
 106         select ARCH_KEEP_MEMBLOCK
 107         select ARCH_SAVE_PAGE_KEYS if HIBERNATION
 108         select ARCH_SUPPORTS_ATOMIC_RMW
 109         select ARCH_SUPPORTS_NUMA_BALANCING
 110         select ARCH_USE_BUILTIN_BSWAP
 111         select ARCH_USE_CMPXCHG_LOCKREF
 112         select ARCH_WANTS_DYNAMIC_TASK_STRUCT
 113         select ARCH_WANT_IPC_PARSE_VERSION
 114         select BUILDTIME_EXTABLE_SORT
 115         select CLONE_BACKWARDS2
 116         select DYNAMIC_FTRACE if FUNCTION_TRACER
 117         select GENERIC_CLOCKEVENTS
 118         select GENERIC_CPU_AUTOPROBE
 119         select GENERIC_CPU_VULNERABILITIES
 120         select GENERIC_FIND_FIRST_BIT
 121         select GENERIC_SMP_IDLE_THREAD
 122         select GENERIC_TIME_VSYSCALL
 123         select HAVE_ALIGNED_STRUCT_PAGE if SLUB
 124         select HAVE_ARCH_AUDITSYSCALL
 125         select HAVE_ARCH_JUMP_LABEL
 126         select HAVE_ARCH_JUMP_LABEL_RELATIVE
 127         select HAVE_ARCH_KASAN
 128         select CPU_NO_EFFICIENT_FFS if !HAVE_MARCH_Z9_109_FEATURES
 129         select HAVE_ARCH_SECCOMP_FILTER
 130         select HAVE_ARCH_SOFT_DIRTY
 131         select HAVE_ARCH_TRACEHOOK
 132         select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 133         select HAVE_ARCH_VMAP_STACK
 134         select HAVE_EBPF_JIT if PACK_STACK && HAVE_MARCH_Z196_FEATURES
 135         select HAVE_CMPXCHG_DOUBLE
 136         select HAVE_CMPXCHG_LOCAL
 137         select HAVE_COPY_THREAD_TLS
 138         select HAVE_DEBUG_KMEMLEAK
 139         select HAVE_DMA_CONTIGUOUS
 140         select HAVE_DYNAMIC_FTRACE
 141         select HAVE_DYNAMIC_FTRACE_WITH_REGS
 142         select HAVE_FAST_GUP
 143         select HAVE_EFFICIENT_UNALIGNED_ACCESS
 144         select HAVE_FENTRY
 145         select HAVE_FTRACE_MCOUNT_RECORD
 146         select HAVE_FUNCTION_GRAPH_TRACER
 147         select HAVE_FUNCTION_TRACER
 148         select HAVE_FUTEX_CMPXCHG if FUTEX
 149         select HAVE_GCC_PLUGINS
 150         select HAVE_KERNEL_BZIP2
 151         select HAVE_KERNEL_GZIP
 152         select HAVE_KERNEL_LZ4
 153         select HAVE_KERNEL_LZMA
 154         select HAVE_KERNEL_LZO
 155         select HAVE_KERNEL_UNCOMPRESSED
 156         select HAVE_KERNEL_XZ
 157         select HAVE_KPROBES
 158         select HAVE_KRETPROBES
 159         select HAVE_KVM
 160         select HAVE_LIVEPATCH
 161         select HAVE_PERF_REGS
 162         select HAVE_PERF_USER_STACK_DUMP
 163         select HAVE_MEMBLOCK_NODE_MAP
 164         select HAVE_MEMBLOCK_PHYS_MAP
 165         select HAVE_MMU_GATHER_NO_GATHER
 166         select HAVE_MOD_ARCH_SPECIFIC
 167         select HAVE_NOP_MCOUNT
 168         select HAVE_OPROFILE
 169         select HAVE_PCI
 170         select HAVE_PERF_EVENTS
 171         select HAVE_RCU_TABLE_FREE
 172         select HAVE_REGS_AND_STACK_ACCESS_API
 173         select HAVE_RSEQ
 174         select HAVE_SYSCALL_TRACEPOINTS
 175         select HAVE_VIRT_CPU_ACCOUNTING
 176         select IOMMU_HELPER             if PCI
 177         select IOMMU_SUPPORT            if PCI
 178         select MODULES_USE_ELF_RELA
 179         select NEED_DMA_MAP_STATE       if PCI
 180         select NEED_SG_DMA_LENGTH       if PCI
 181         select OLD_SIGACTION
 182         select OLD_SIGSUSPEND3
 183         select PCI_DOMAINS              if PCI
 184         select PCI_MSI                  if PCI
 185         select SPARSE_IRQ
 186         select SYSCTL_EXCEPTION_TRACE
 187         select THREAD_INFO_IN_TASK
 188         select TTY
 189         select VIRT_CPU_ACCOUNTING
 190         select ARCH_HAS_SCALED_CPUTIME
 191         select HAVE_NMI
 192         select ARCH_HAS_FORCE_DMA_UNENCRYPTED
 193         select SWIOTLB
 194         select GENERIC_ALLOCATOR
 195
 196
 197 config SCHED_OMIT_FRAME_POINTER
 198         def_bool y
 199
 200 config PGTABLE_LEVELS
 201         int
 202         default 5
 203
 204 source "kernel/livepatch/Kconfig"
 205
 206 menu "Processor type and features"
 207
 208 config HAVE_MARCH_Z900_FEATURES
 209         def_bool n
 210
 211 config HAVE_MARCH_Z990_FEATURES
 212         def_bool n
 213         select HAVE_MARCH_Z900_FEATURES
 214
 215 config HAVE_MARCH_Z9_109_FEATURES
 216         def_bool n
 217         select HAVE_MARCH_Z990_FEATURES
 218
 219 config HAVE_MARCH_Z10_FEATURES
 220         def_bool n
 221         select HAVE_MARCH_Z9_109_FEATURES
 222
 223 config HAVE_MARCH_Z196_FEATURES
 224         def_bool n
 225         select HAVE_MARCH_Z10_FEATURES
 226
 227 config HAVE_MARCH_ZEC12_FEATURES
 228         def_bool n
 229         select HAVE_MARCH_Z196_FEATURES
 230
 231 config HAVE_MARCH_Z13_FEATURES
 232         def_bool n
 233         select HAVE_MARCH_ZEC12_FEATURES
 234
 235 config HAVE_MARCH_Z14_FEATURES
 236         def_bool n
 237         select HAVE_MARCH_Z13_FEATURES
 238
 239 choice
 240         prompt "Processor type"
 241         default MARCH_Z196
 242
 243 config MARCH_Z900
 244         bool "IBM zSeries model z800 and z900"
 245         depends on !CC_IS_CLANG
 246         select HAVE_MARCH_Z900_FEATURES
 247         help
 248           Select this to enable optimizations for model z800/z900 (2064 and
 249           2066 series). This will enable some optimizations that are not
 250           available on older ESA/390 (31 Bit) only CPUs.
 251
 252 config MARCH_Z990
 253         bool "IBM zSeries model z890 and z990"
 254         depends on !CC_IS_CLANG
 255         select HAVE_MARCH_Z990_FEATURES
 256         help
 257           Select this to enable optimizations for model z890/z990 (2084 and
 258           2086 series). The kernel will be slightly faster but will not work
 259           on older machines.
 260
 261 config MARCH_Z9_109
 262         bool "IBM System z9"
 263         depends on !CC_IS_CLANG
 264         select HAVE_MARCH_Z9_109_FEATURES
 265         help
 266           Select this to enable optimizations for IBM System z9 (2094 and
 267           2096 series). The kernel will be slightly faster but will not work
 268           on older machines.
 269
 270 config MARCH_Z10
 271         bool "IBM System z10"
 272         select HAVE_MARCH_Z10_FEATURES
 273         help
 274           Select this to enable optimizations for IBM System z10 (2097 and
 275           2098 series). The kernel will be slightly faster but will not work
 276           on older machines.
 277
 278 config MARCH_Z196
 279         bool "IBM zEnterprise 114 and 196"
 280         select HAVE_MARCH_Z196_FEATURES
 281         help
 282           Select this to enable optimizations for IBM zEnterprise 114 and 196
 283           (2818 and 2817 series). The kernel will be slightly faster but will
 284           not work on older machines.
 285
 286 config MARCH_ZEC12
 287         bool "IBM zBC12 and zEC12"
 288         select HAVE_MARCH_ZEC12_FEATURES
 289         help
 290           Select this to enable optimizations for IBM zBC12 and zEC12 (2828 and
 291           2827 series). The kernel will be slightly faster but will not work on
 292           older machines.
 293
 294 config MARCH_Z13
 295         bool "IBM z13s and z13"
 296         select HAVE_MARCH_Z13_FEATURES
 297         help
 298           Select this to enable optimizations for IBM z13s and z13 (2965 and
 299           2964 series). The kernel will be slightly faster but will not work on
 300           older machines.
 301
 302 config MARCH_Z14
 303         bool "IBM z14 ZR1 and z14"
 304         select HAVE_MARCH_Z14_FEATURES
 305         help
 306           Select this to enable optimizations for IBM z14 ZR1 and z14 (3907
 307           and 3906 series). The kernel will be slightly faster but will not
 308           work on older machines.
 309
 310 endchoice
 311
 312 config MARCH_Z900_TUNE
 313         def_bool TUNE_Z900 || MARCH_Z900 && TUNE_DEFAULT
 314
 315 config MARCH_Z990_TUNE
 316         def_bool TUNE_Z990 || MARCH_Z990 && TUNE_DEFAULT
 317
 318 config MARCH_Z9_109_TUNE
 319         def_bool TUNE_Z9_109 || MARCH_Z9_109 && TUNE_DEFAULT
 320
 321 config MARCH_Z10_TUNE
 322         def_bool TUNE_Z10 || MARCH_Z10 && TUNE_DEFAULT
 323
 324 config MARCH_Z196_TUNE
 325         def_bool TUNE_Z196 || MARCH_Z196 && TUNE_DEFAULT
 326
 327 config MARCH_ZEC12_TUNE
 328         def_bool TUNE_ZEC12 || MARCH_ZEC12 && TUNE_DEFAULT
 329
 330 config MARCH_Z13_TUNE
 331         def_bool TUNE_Z13 || MARCH_Z13 && TUNE_DEFAULT
 332
 333 config MARCH_Z14_TUNE
 334         def_bool TUNE_Z14 || MARCH_Z14 && TUNE_DEFAULT
 335
 336 choice
 337         prompt "Tune code generation"
 338         default TUNE_DEFAULT
 339         help
 340           Cause the compiler to tune (-mtune) the generated code for a machine.
 341           This will make the code run faster on the selected machine but
 342           somewhat slower on other machines.
 343           This option only changes how the compiler emits instructions, not the
 344           selection of instructions itself, so the resulting kernel will run on
 345           all other machines.
 346
 347 config TUNE_DEFAULT
 348         bool "Default"
 349         help
 350           Tune the generated code for the target processor for which the kernel
 351           will be compiled.
 352
 353 config TUNE_Z900
 354         bool "IBM zSeries model z800 and z900"
 355         depends on !CC_IS_CLANG
 356
 357 config TUNE_Z990
 358         bool "IBM zSeries model z890 and z990"
 359         depends on !CC_IS_CLANG
 360
 361 config TUNE_Z9_109
 362         bool "IBM System z9"
 363         depends on !CC_IS_CLANG
 364
 365 config TUNE_Z10
 366         bool "IBM System z10"
 367
 368 config TUNE_Z196
 369         bool "IBM zEnterprise 114 and 196"
 370
 371 config TUNE_ZEC12
 372         bool "IBM zBC12 and zEC12"
 373
 374 config TUNE_Z13
 375         bool "IBM z13"
 376
 377 config TUNE_Z14
 378         bool "IBM z14"
 379
 380 endchoice
 381
 382 config 64BIT
 383         def_bool y
 384
 385 config COMPAT
 386         def_bool y
 387         prompt "Kernel support for 31 bit emulation"
 388         select COMPAT_BINFMT_ELF if BINFMT_ELF
 389         select ARCH_WANT_OLD_COMPAT_IPC
 390         select COMPAT_OLD_SIGACTION
 391         select HAVE_UID16
 392         depends on MULTIUSER
 393         help
 394           Select this option if you want to enable your system kernel to
 395           handle system-calls from ELF binaries for 31 bit ESA.  This option
 396           (and some other stuff like libraries and such) is needed for
 397           executing 31 bit applications.  It is safe to say "Y".
 398
 399 config COMPAT_VDSO
 400         def_bool COMPAT && !CC_IS_CLANG
 401
 402 config SYSVIPC_COMPAT
 403         def_bool y if COMPAT && SYSVIPC
 404
 405 config SMP
 406         def_bool y
 407
 408 config NR_CPUS
 409         int "Maximum number of CPUs (2-512)"
 410         range 2 512
 411         default "64"
 412         help
 413           This allows you to specify the maximum number of CPUs which this
 414           kernel will support. The maximum supported value is 512 and the
 415           minimum value which makes sense is 2.
 416
 417           This is purely to save memory - each supported CPU adds
 418           approximately sixteen kilobytes to the kernel image.
 419
 420 config HOTPLUG_CPU
 421         def_bool y
 422
 423 # Some NUMA nodes have memory ranges that span
 424 # other nodes.  Even though a pfn is valid and
 425 # between a node's start and end pfns, it may not
 426 # reside on that node.  See memmap_init_zone()
 427 # for details. <- They meant memory holes!
 428 config NODES_SPAN_OTHER_NODES
 429         def_bool NUMA
 430
 431 config NUMA
 432         bool "NUMA support"
 433         depends on SCHED_TOPOLOGY
 434         default n
 435         help
 436           Enable NUMA support
 437
 438           This option adds NUMA support to the kernel.
 439
 440           An operation mode can be selected by appending
 441           numa=<method> to the kernel command line.
 442
 443           The default behaviour is identical to appending numa=plain to
 444           the command line. This will create just one node with all
 445           available memory and all CPUs in it.
 446
 447 config NODES_SHIFT
 448         int "Maximum NUMA nodes (as a power of 2)"
 449         range 1 10
 450         depends on NUMA
 451         default "4"
 452         help
 453           Specify the maximum number of NUMA nodes available on the target
 454           system. Increases memory reserved to accommodate various tables.
 455
 456 menu "Select NUMA modes"
 457         depends on NUMA
 458
 459 config NUMA_EMU
 460         bool "NUMA emulation"
 461         default y
 462         help
 463           Numa emulation mode will split the available system memory into
 464           equal chunks which then are distributed over the configured number
 465           of nodes in a round-robin manner.
 466
 467           The number of fake nodes is limited by the number of available memory
 468           chunks (i.e. memory size / fake size) and the number of supported
 469           nodes in the kernel.
 470
 471           The CPUs are assigned to the nodes in a way that partially respects
 472           the original machine topology (if supported by the machine).
 473           Fair distribution of the CPUs is not guaranteed.
 474
 475 config EMU_SIZE
 476         hex "NUMA emulation memory chunk size"
 477         default 0x10000000
 478         range 0x400000 0x100000000
 479         depends on NUMA_EMU
 480         help
 481           Select the default size by which the memory is chopped and then
 482           assigned to emulated NUMA nodes.
 483
 484           This can be overridden by specifying
 485
 486           emu_size=<n>
 487
 488           on the kernel command line where also suffixes K, M, G, and T are
 489           supported.
 490
 491 endmenu
 492
 493 config SCHED_SMT
 494         def_bool n
 495
 496 config SCHED_MC
 497         def_bool n
 498
 499 config SCHED_BOOK
 500         def_bool n
 501
 502 config SCHED_DRAWER
 503         def_bool n
 504
 505 config SCHED_TOPOLOGY
 506         def_bool y
 507         prompt "Topology scheduler support"
 508         select SCHED_SMT
 509         select SCHED_MC
 510         select SCHED_BOOK
 511         select SCHED_DRAWER
 512         help
 513           Topology scheduler support improves the CPU scheduler's decision
 514           making when dealing with machines that have multi-threading,
 515           multiple cores or multiple books.
 516
 517 source "kernel/Kconfig.hz"
 518
 519 config KEXEC
 520         def_bool y
 521         select KEXEC_CORE
 522
 523 config KEXEC_FILE
 524         bool "kexec file based system call"
 525         select KEXEC_CORE
 526         select BUILD_BIN2C
 527         depends on CRYPTO
 528         depends on CRYPTO_SHA256
 529         depends on CRYPTO_SHA256_S390
 530         help
 531           Enable the kexec file based system call. In contrast to the normal
 532           kexec system call this system call takes file descriptors for the
 533           kernel and initramfs as arguments.
 534
 535 config ARCH_HAS_KEXEC_PURGATORY
 536         def_bool y
 537         depends on KEXEC_FILE
 538
 539 config KEXEC_VERIFY_SIG
 540         bool "Verify kernel signature during kexec_file_load() syscall"
 541         depends on KEXEC_FILE && SYSTEM_DATA_VERIFICATION
 542         help
 543           This option makes kernel signature verification mandatory for
 544           the kexec_file_load() syscall.
 545
 546           In addition to that option, you need to enable signature
 547           verification for the corresponding kernel image type being
 548           loaded in order for this to work.
 549
 550 config ARCH_RANDOM
 551         def_bool y
 552         prompt "s390 architectural random number generation API"
 553         help
 554           Enable the s390 architectural random number generation API
 555           to provide random data for all consumers within the Linux
 556           kernel.
 557
 558           When enabled the arch_random_* functions declared in linux/random.h
 559           are implemented. The implementation is based on the s390 CPACF
 560           instruction subfunction TRNG which provides a real true random
 561           number generator.
 562
 563           If unsure, say Y.
 564
 565 config KERNEL_NOBP
 566         def_bool n
 567         prompt "Enable modified branch prediction for the kernel by default"
 568         help
 569           If this option is selected the kernel will switch to a modified
 570           branch prediction mode if the firmware interface is available.
 571           The modified branch prediction mode improves the behaviour in
 572           regard to speculative execution.
 573
 574           With the option enabled the kernel parameter "nobp=0" or "nospec"
 575           can be used to run the kernel in the normal branch prediction mode.
 576
 577           With the option disabled the modified branch prediction mode is
 578           enabled with the "nobp=1" kernel parameter.
 579
 580           If unsure, say N.
 581
 582 config EXPOLINE
 583         def_bool n
 584         prompt "Avoid speculative indirect branches in the kernel"
 585         help
 586           Compile the kernel with the expoline compiler options to guard
 587           against kernel-to-user data leaks by avoiding speculative indirect
 588           branches.
 589           Requires a compiler with -mindirect-branch=thunk support for full
 590           protection. The kernel may run slower.
 591
 592           If unsure, say N.
 593
 594 choice
 595         prompt "Expoline default"
 596         depends on EXPOLINE
 597         default EXPOLINE_FULL
 598
 599 config EXPOLINE_OFF
 600         bool "spectre_v2=off"
 601
 602 config EXPOLINE_AUTO
 603         bool "spectre_v2=auto"
 604
 605 config EXPOLINE_FULL
 606         bool "spectre_v2=on"
 607
 608 endchoice
 609
 610 config RELOCATABLE
 611         bool "Build a relocatable kernel"
 612         select MODULE_REL_CRCS if MODVERSIONS
 613         default y
 614         help
 615           This builds a kernel image that retains relocation information
 616           so it can be loaded at an arbitrary address.
 617           The kernel is linked as a position-independent executable (PIE)
 618           and contains dynamic relocations which are processed early in the
 619           bootup process.
 620           The relocations make the kernel image about 15% larger (compressed
 621           10%), but are discarded at runtime.
 622
 623 config RANDOMIZE_BASE
 624         bool "Randomize the address of the kernel image (KASLR)"
 625         depends on RELOCATABLE
 626         default y
 627         help
 628           In support of Kernel Address Space Layout Randomization (KASLR),
 629           this randomizes the address at which the kernel image is loaded,
 630           as a security feature that deters exploit attempts relying on
 631           knowledge of the location of kernel internals.
 632
 633 endmenu
 634
 635 menu "Memory setup"
 636
 637 config ARCH_SPARSEMEM_ENABLE
 638         def_bool y
 639         select SPARSEMEM_VMEMMAP_ENABLE
 640         select SPARSEMEM_VMEMMAP
 641
 642 config ARCH_SPARSEMEM_DEFAULT
 643         def_bool y
 644
 645 config ARCH_ENABLE_MEMORY_HOTPLUG
 646         def_bool y if SPARSEMEM
 647
 648 config ARCH_ENABLE_MEMORY_HOTREMOVE
 649         def_bool y
 650
 651 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 652         def_bool y
 653
 654 config FORCE_MAX_ZONEORDER
 655         int
 656         default "9"
 657
 658 config MAX_PHYSMEM_BITS
 659         int "Maximum size of supported physical memory in bits (42-53)"
 660         range 42 53
 661         default "46"
 662         help
 663           This option specifies the maximum supported size of physical memory
 664           in bits. Supported is any size between 2^42 (4TB) and 2^53 (8PB).
 665           Increasing the number of bits also increases the kernel image size.
 666           By default 46 bits (64TB) are supported.
 667
 668 config PACK_STACK
 669         def_bool y
 670         prompt "Pack kernel stack"
 671         help
 672           This option enables the compiler option -mkernel-backchain if it
 673           is available. If the option is available the compiler supports
 674           the new stack layout which dramatically reduces the minimum stack
 675           frame size. With an old compiler a non-leaf function needs a
 676           minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
 677           -mkernel-backchain the minimum size drops to 16 byte on 31 bit
 678           and 24 byte on 64 bit.
 679
 680           Say Y if you are unsure.
 681
 682 config CHECK_STACK
 683         def_bool y
 684         depends on !VMAP_STACK
 685         prompt "Detect kernel stack overflow"
 686         help
 687           This option enables the compiler option -mstack-guard and
 688           -mstack-size if they are available. If the compiler supports them
 689           it will emit additional code to each function prolog to trigger
 690           an illegal operation if the kernel stack is about to overflow.
 691
 692           Say N if you are unsure.
 693
 694 config STACK_GUARD
 695         int "Size of the guard area (128-1024)"
 696         range 128 1024
 697         depends on CHECK_STACK
 698         default "256"
 699         help
 700           This allows you to specify the size of the guard area at the lower
 701           end of the kernel stack. If the kernel stack points into the guard
 702           area on function entry an illegal operation is triggered. The size
 703           needs to be a power of 2. Please keep in mind that the size of an
 704           interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
 705           The minimum size for the stack guard should be 256 for 31 bit and
 706           512 for 64 bit.
 707
 708 config WARN_DYNAMIC_STACK
 709         def_bool n
 710         prompt "Emit compiler warnings for function with dynamic stack usage"
 711         help
 712           This option enables the compiler option -mwarn-dynamicstack. If the
 713           compiler supports this options generates warnings for functions
 714           that dynamically allocate stack space using alloca.
 715
 716           Say N if you are unsure.
 717
 718 endmenu
 719
 720 menu "I/O subsystem"
 721
 722 config QDIO
 723         def_tristate y
 724         prompt "QDIO support"
 725         ---help---
 726           This driver provides the Queued Direct I/O base support for
 727           IBM System z.
 728
 729           To compile this driver as a module, choose M here: the
 730           module will be called qdio.
 731
 732           If unsure, say Y.
 733
 734 if PCI
 735
 736 config PCI_NR_FUNCTIONS
 737         int "Maximum number of PCI functions (1-4096)"
 738         range 1 4096
 739         default "128"
 740         help
 741           This allows you to specify the maximum number of PCI functions which
 742           this kernel will support.
 743
 744 endif # PCI
 745
 746 config HAS_IOMEM
 747         def_bool PCI
 748
 749 config CHSC_SCH
 750         def_tristate m
 751         prompt "Support for CHSC subchannels"
 752         help
 753           This driver allows usage of CHSC subchannels. A CHSC subchannel
 754           is usually present on LPAR only.
 755           The driver creates a device /dev/chsc, which may be used to
 756           obtain I/O configuration information about the machine and
 757           to issue asynchronous chsc commands (DANGEROUS).
 758           You will usually only want to use this interface on a special
 759           LPAR designated for system management.
 760
 761           To compile this driver as a module, choose M here: the
 762           module will be called chsc_sch.
 763
 764           If unsure, say N.
 765
 766 config SCM_BUS
 767         def_bool y
 768         prompt "SCM bus driver"
 769         help
 770           Bus driver for Storage Class Memory.
 771
 772 config EADM_SCH
 773         def_tristate m
 774         prompt "Support for EADM subchannels"
 775         depends on SCM_BUS
 776         help
 777           This driver allows usage of EADM subchannels. EADM subchannels act
 778           as a communication vehicle for SCM increments.
 779
 780           To compile this driver as a module, choose M here: the
 781           module will be called eadm_sch.
 782
 783 config VFIO_CCW
 784         def_tristate n
 785         prompt "Support for VFIO-CCW subchannels"
 786         depends on S390_CCW_IOMMU && VFIO_MDEV
 787         help
 788           This driver allows usage of I/O subchannels via VFIO-CCW.
 789
 790           To compile this driver as a module, choose M here: the
 791           module will be called vfio_ccw.
 792
 793 config VFIO_AP
 794         def_tristate n
 795         prompt "VFIO support for AP devices"
 796         depends on S390_AP_IOMMU && VFIO_MDEV_DEVICE && KVM
 797         help
 798                 This driver grants access to Adjunct Processor (AP) devices
 799                 via the VFIO mediated device interface.
 800
 801                 To compile this driver as a module, choose M here: the module
 802                 will be called vfio_ap.
 803
 804 endmenu
 805
 806 menu "Dump support"
 807
 808 config CRASH_DUMP
 809         bool "kernel crash dumps"
 810         select KEXEC
 811         help
 812           Generate crash dump after being started by kexec.
 813           Crash dump kernels are loaded in the main kernel with kexec-tools
 814           into a specially reserved region and then later executed after
 815           a crash by kdump/kexec.
 816           Refer to <file:Documentation/s390/zfcpdump.rst> for more details on this.
 817           This option also enables s390 zfcpdump.
 818           See also <file:Documentation/s390/zfcpdump.rst>
 819
 820 endmenu
 821
 822 config SECCOMP
 823         def_bool y
 824         prompt "Enable seccomp to safely compute untrusted bytecode"
 825         depends on PROC_FS
 826         help
 827           This kernel feature is useful for number crunching applications
 828           that may need to compute untrusted bytecode during their
 829           execution. By using pipes or other transports made available to
 830           the process as file descriptors supporting the read/write
 831           syscalls, it's possible to isolate those applications in
 832           their own address space using seccomp. Once seccomp is
 833           enabled via /proc/<pid>/seccomp, it cannot be disabled
 834           and the task is only allowed to execute a few safe syscalls
 835           defined by each seccomp mode.
 836
 837           If unsure, say Y.
 838
 839 menu "Power Management"
 840
 841 config ARCH_HIBERNATION_POSSIBLE
 842         def_bool y
 843
 844 source "kernel/power/Kconfig"
 845
 846 endmenu
 847
 848 config CCW
 849         def_bool y
 850
 851 config HAVE_PNETID
 852         tristate
 853         default (SMC || CCWGROUP)
 854
 855 menu "Virtualization"
 856
 857 config PROTECTED_VIRTUALIZATION_GUEST
 858         def_bool n
 859         prompt "Protected virtualization guest support"
 860         help
 861           Select this option, if you want to be able to run this
 862           kernel as a protected virtualization KVM guest.
 863           Protected virtualization capable machines have a mini hypervisor
 864           located at machine level (an ultravisor). With help of the
 865           Ultravisor, KVM will be able to run "protected" VMs, special
 866           VMs whose memory and management data are unavailable to KVM.
 867
 868 config PFAULT
 869         def_bool y
 870         prompt "Pseudo page fault support"
 871         help
 872           Select this option, if you want to use PFAULT pseudo page fault
 873           handling under VM. If running native or in LPAR, this option
 874           has no effect. If your VM does not support PFAULT, PAGEEX
 875           pseudo page fault handling will be used.
 876           Note that VM 4.2 supports PFAULT but has a bug in its
 877           implementation that causes some problems.
 878           Everybody who wants to run Linux under VM != VM4.2 should select
 879           this option.
 880
 881 config CMM
 882         def_tristate n
 883         prompt "Cooperative memory management"
 884         help
 885           Select this option, if you want to enable the kernel interface
 886           to reduce the memory size of the system. This is accomplished
 887           by allocating pages of memory and put them "on hold". This only
 888           makes sense for a system running under VM where the unused pages
 889           will be reused by VM for other guest systems. The interface
 890           allows an external monitor to balance memory of many systems.
 891           Everybody who wants to run Linux under VM should select this
 892           option.
 893
 894 config CMM_IUCV
 895         def_bool y
 896         prompt "IUCV special message interface to cooperative memory management"
 897         depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
 898         help
 899           Select this option to enable the special message interface to
 900           the cooperative memory management.
 901
 902 config APPLDATA_BASE
 903         def_bool n
 904         prompt "Linux - VM Monitor Stream, base infrastructure"
 905         depends on PROC_FS
 906         help
 907           This provides a kernel interface for creating and updating z/VM APPLDATA
 908           monitor records. The monitor records are updated at certain time
 909           intervals, once the timer is started.
 910           Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
 911           i.e. enables or disables monitoring on the Linux side.
 912           A custom interval value (in seconds) can be written to
 913           /proc/appldata/interval.
 914
 915           Defaults are 60 seconds interval and timer off.
 916           The /proc entries can also be read from, showing the current settings.
 917
 918 config APPLDATA_MEM
 919         def_tristate m
 920         prompt "Monitor memory management statistics"
 921         depends on APPLDATA_BASE && VM_EVENT_COUNTERS
 922         help
 923           This provides memory management related data to the Linux - VM Monitor
 924           Stream, like paging/swapping rate, memory utilisation, etc.
 925           Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
 926           APPLDATA monitor record, i.e. enables or disables monitoring this record
 927           on the z/VM side.
 928
 929           Default is disabled.
 930           The /proc entry can also be read from, showing the current settings.
 931
 932           This can also be compiled as a module, which will be called
 933           appldata_mem.o.
 934
 935 config APPLDATA_OS
 936         def_tristate m
 937         prompt "Monitor OS statistics"
 938         depends on APPLDATA_BASE
 939         help
 940           This provides OS related data to the Linux - VM Monitor Stream, like
 941           CPU utilisation, etc.
 942           Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
 943           APPLDATA monitor record, i.e. enables or disables monitoring this record
 944           on the z/VM side.
 945
 946           Default is disabled.
 947           This can also be compiled as a module, which will be called
 948           appldata_os.o.
 949
 950 config APPLDATA_NET_SUM
 951         def_tristate m
 952         prompt "Monitor overall network statistics"
 953         depends on APPLDATA_BASE && NET
 954         help
 955           This provides network related data to the Linux - VM Monitor Stream,
 956           currently there is only a total sum of network I/O statistics, no
 957           per-interface data.
 958           Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
 959           APPLDATA monitor record, i.e. enables or disables monitoring this record
 960           on the z/VM side.
 961
 962           Default is disabled.
 963           This can also be compiled as a module, which will be called
 964           appldata_net_sum.o.
 965
 966 config S390_HYPFS_FS
 967         def_bool y
 968         prompt "s390 hypervisor file system support"
 969         select SYS_HYPERVISOR
 970         help
 971           This is a virtual file system intended to provide accounting
 972           information in an s390 hypervisor environment.
 973
 974 source "arch/s390/kvm/Kconfig"
 975
 976 config S390_GUEST
 977         def_bool y
 978         prompt "s390 support for virtio devices"
 979         select TTY
 980         select VIRTUALIZATION
 981         select VIRTIO
 982         select VIRTIO_CONSOLE
 983         help
 984           Enabling this option adds support for virtio based paravirtual device
 985           drivers on s390.
 986
 987           Select this option if you want to run the kernel as a guest under
 988           the KVM hypervisor.
 989
 990 endmenu