arch/s390/Kconfig

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