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 RWSEM_GENERIC_SPINLOCK
  18         bool
  19
  20 config RWSEM_XCHGADD_ALGORITHM
  21         def_bool y
  22
  23 config ARCH_HAS_ILOG2_U32
  24         def_bool n
  25
  26 config ARCH_HAS_ILOG2_U64
  27         def_bool n
  28
  29 config GENERIC_HWEIGHT
  30         def_bool y
  31
  32 config GENERIC_BUG
  33         def_bool y if BUG
  34
  35 config GENERIC_BUG_RELATIVE_POINTERS
  36         def_bool y
  37
  38 config GENERIC_LOCKBREAK
  39         def_bool y if SMP && PREEMPT
  40
  41 config PGSTE
  42         def_bool y if KVM
  43
  44 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
  45         def_bool y
  46
  47 config AUDIT_ARCH
  48         def_bool y
  49
  50 config NO_IOPORT_MAP
  51         def_bool y
  52
  53 config PCI_QUIRKS
  54         def_bool n
  55
  56 config ARCH_SUPPORTS_UPROBES
  57         def_bool y
  58
  59 config KASAN_SHADOW_OFFSET
  60         hex
  61         depends on KASAN
  62         default 0x18000000000000 if KASAN_S390_4_LEVEL_PAGING
  63         default 0x30000000000
  64
  65 config S390
  66         def_bool y
  67         select ARCH_BINFMT_ELF_STATE
  68         select ARCH_HAS_DEVMEM_IS_ALLOWED
  69         select ARCH_HAS_ELF_RANDOMIZE
  70         select ARCH_HAS_FORTIFY_SOURCE
  71         select ARCH_HAS_GCOV_PROFILE_ALL
  72         select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
  73         select ARCH_HAS_KCOV
  74         select ARCH_HAS_PTE_SPECIAL
  75         select ARCH_HAS_SET_MEMORY
  76         select ARCH_HAS_SG_CHAIN
  77         select ARCH_HAS_STRICT_KERNEL_RWX
  78         select ARCH_HAS_STRICT_MODULE_RWX
  79         select ARCH_HAS_UBSAN_SANITIZE_ALL
  80         select ARCH_HAVE_NMI_SAFE_CMPXCHG
  81         select ARCH_INLINE_READ_LOCK
  82         select ARCH_INLINE_READ_LOCK_BH
  83         select ARCH_INLINE_READ_LOCK_IRQ
  84         select ARCH_INLINE_READ_LOCK_IRQSAVE
  85         select ARCH_INLINE_READ_TRYLOCK
  86         select ARCH_INLINE_READ_UNLOCK
  87         select ARCH_INLINE_READ_UNLOCK_BH
  88         select ARCH_INLINE_READ_UNLOCK_IRQ
  89         select ARCH_INLINE_READ_UNLOCK_IRQRESTORE
  90         select ARCH_INLINE_SPIN_LOCK
  91         select ARCH_INLINE_SPIN_LOCK_BH
  92         select ARCH_INLINE_SPIN_LOCK_IRQ
  93         select ARCH_INLINE_SPIN_LOCK_IRQSAVE
  94         select ARCH_INLINE_SPIN_TRYLOCK
  95         select ARCH_INLINE_SPIN_TRYLOCK_BH
  96         select ARCH_INLINE_SPIN_UNLOCK
  97         select ARCH_INLINE_SPIN_UNLOCK_BH
  98         select ARCH_INLINE_SPIN_UNLOCK_IRQ
  99         select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE
 100         select ARCH_INLINE_WRITE_LOCK
 101         select ARCH_INLINE_WRITE_LOCK_BH
 102         select ARCH_INLINE_WRITE_LOCK_IRQ
 103         select ARCH_INLINE_WRITE_LOCK_IRQSAVE
 104         select ARCH_INLINE_WRITE_TRYLOCK
 105         select ARCH_INLINE_WRITE_UNLOCK
 106         select ARCH_INLINE_WRITE_UNLOCK_BH
 107         select ARCH_INLINE_WRITE_UNLOCK_IRQ
 108         select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
 109         select ARCH_SAVE_PAGE_KEYS if HIBERNATION
 110         select ARCH_SUPPORTS_ATOMIC_RMW
 111         select ARCH_SUPPORTS_NUMA_BALANCING
 112         select ARCH_USE_BUILTIN_BSWAP
 113         select ARCH_USE_CMPXCHG_LOCKREF
 114         select ARCH_WANTS_DYNAMIC_TASK_STRUCT
 115         select ARCH_WANT_IPC_PARSE_VERSION
 116         select BUILDTIME_EXTABLE_SORT
 117         select CLONE_BACKWARDS2
 118         select DYNAMIC_FTRACE if FUNCTION_TRACER
 119         select GENERIC_CLOCKEVENTS
 120         select GENERIC_CPU_AUTOPROBE
 121         select GENERIC_CPU_DEVICES if !SMP
 122         select GENERIC_CPU_VULNERABILITIES
 123         select GENERIC_FIND_FIRST_BIT
 124         select GENERIC_SMP_IDLE_THREAD
 125         select GENERIC_TIME_VSYSCALL
 126         select HAVE_ALIGNED_STRUCT_PAGE if SLUB
 127         select HAVE_ARCH_AUDITSYSCALL
 128         select HAVE_ARCH_JUMP_LABEL
 129         select HAVE_ARCH_JUMP_LABEL_RELATIVE
 130         select HAVE_ARCH_KASAN
 131         select CPU_NO_EFFICIENT_FFS if !HAVE_MARCH_Z9_109_FEATURES
 132         select HAVE_ARCH_SECCOMP_FILTER
 133         select HAVE_ARCH_SOFT_DIRTY
 134         select HAVE_ARCH_TRACEHOOK
 135         select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 136         select HAVE_ARCH_VMAP_STACK
 137         select HAVE_EBPF_JIT if PACK_STACK && HAVE_MARCH_Z196_FEATURES
 138         select HAVE_CMPXCHG_DOUBLE
 139         select HAVE_CMPXCHG_LOCAL
 140         select HAVE_COPY_THREAD_TLS
 141         select HAVE_DEBUG_KMEMLEAK
 142         select HAVE_DMA_CONTIGUOUS
 143         select DMA_DIRECT_OPS
 144         select HAVE_DYNAMIC_FTRACE
 145         select HAVE_DYNAMIC_FTRACE_WITH_REGS
 146         select HAVE_EFFICIENT_UNALIGNED_ACCESS
 147         select HAVE_FENTRY
 148         select HAVE_FTRACE_MCOUNT_RECORD
 149         select HAVE_FUNCTION_GRAPH_TRACER
 150         select HAVE_FUNCTION_TRACER
 151         select HAVE_FUTEX_CMPXCHG if FUTEX
 152         select HAVE_GCC_PLUGINS
 153         select HAVE_KERNEL_BZIP2
 154         select HAVE_KERNEL_GZIP
 155         select HAVE_KERNEL_LZ4
 156         select HAVE_KERNEL_LZMA
 157         select HAVE_KERNEL_LZO
 158         select HAVE_KERNEL_UNCOMPRESSED
 159         select HAVE_KERNEL_XZ
 160         select HAVE_KPROBES
 161         select HAVE_KRETPROBES
 162         select HAVE_KVM
 163         select HAVE_LIVEPATCH
 164         select HAVE_PERF_REGS
 165         select HAVE_PERF_USER_STACK_DUMP
 166         select HAVE_MEMBLOCK_NODE_MAP
 167         select HAVE_MEMBLOCK_PHYS_MAP
 168         select HAVE_MOD_ARCH_SPECIFIC
 169         select HAVE_NOP_MCOUNT
 170         select HAVE_OPROFILE
 171         select HAVE_PERF_EVENTS
 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 MODULES_USE_ELF_RELA
 177         select OLD_SIGACTION
 178         select OLD_SIGSUSPEND3
 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         depends on MULTIUSER
 378         help
 379           Select this option if you want to enable your system kernel to
 380           handle system-calls from ELF binaries for 31 bit ESA.  This option
 381           (and some other stuff like libraries and such) is needed for
 382           executing 31 bit applications.  It is safe to say "Y".
 383
 384 config SYSVIPC_COMPAT
 385         def_bool y if COMPAT && SYSVIPC
 386
 387 config SMP
 388         def_bool y
 389         prompt "Symmetric multi-processing support"
 390         ---help---
 391           This enables support for systems with more than one CPU. If you have
 392           a system with only one CPU, like most personal computers, say N. If
 393           you have a system with more than one CPU, say Y.
 394
 395           If you say N here, the kernel will run on uni- and multiprocessor
 396           machines, but will use only one CPU of a multiprocessor machine. If
 397           you say Y here, the kernel will run on many, but not all,
 398           uniprocessor machines. On a uniprocessor machine, the kernel
 399           will run faster if you say N here.
 400
 401           See also the SMP-HOWTO available at
 402           <http://www.tldp.org/docs.html#howto>.
 403
 404           Even if you don't know what to do here, say Y.
 405
 406 config NR_CPUS
 407         int "Maximum number of CPUs (2-512)"
 408         range 2 512
 409         depends on SMP
 410         default "64"
 411         help
 412           This allows you to specify the maximum number of CPUs which this
 413           kernel will support. The maximum supported value is 512 and the
 414           minimum value which makes sense is 2.
 415
 416           This is purely to save memory - each supported CPU adds
 417           approximately sixteen kilobytes to the kernel image.
 418
 419 config HOTPLUG_CPU
 420         def_bool y
 421         prompt "Support for hot-pluggable CPUs"
 422         depends on SMP
 423         help
 424           Say Y here to be able to turn CPUs off and on. CPUs
 425           can be controlled through /sys/devices/system/cpu/cpu#.
 426           Say N if you want to disable CPU hotplug.
 427
 428 # Some NUMA nodes have memory ranges that span
 429 # other nodes.  Even though a pfn is valid and
 430 # between a node's start and end pfns, it may not
 431 # reside on that node.  See memmap_init_zone()
 432 # for details. <- They meant memory holes!
 433 config NODES_SPAN_OTHER_NODES
 434         def_bool NUMA
 435
 436 config NUMA
 437         bool "NUMA support"
 438         depends on SMP && SCHED_TOPOLOGY
 439         default n
 440         help
 441           Enable NUMA support
 442
 443           This option adds NUMA support to the kernel.
 444
 445           An operation mode can be selected by appending
 446           numa=<method> to the kernel command line.
 447
 448           The default behaviour is identical to appending numa=plain to
 449           the command line. This will create just one node with all
 450           available memory and all CPUs in it.
 451
 452 config NODES_SHIFT
 453         int "Maximum NUMA nodes (as a power of 2)"
 454         range 1 10
 455         depends on NUMA
 456         default "4"
 457         help
 458           Specify the maximum number of NUMA nodes available on the target
 459           system. Increases memory reserved to accommodate various tables.
 460
 461 menu "Select NUMA modes"
 462         depends on NUMA
 463
 464 config NUMA_EMU
 465         bool "NUMA emulation"
 466         default y
 467         help
 468           Numa emulation mode will split the available system memory into
 469           equal chunks which then are distributed over the configured number
 470           of nodes in a round-robin manner.
 471
 472           The number of fake nodes is limited by the number of available memory
 473           chunks (i.e. memory size / fake size) and the number of supported
 474           nodes in the kernel.
 475
 476           The CPUs are assigned to the nodes in a way that partially respects
 477           the original machine topology (if supported by the machine).
 478           Fair distribution of the CPUs is not guaranteed.
 479
 480 config EMU_SIZE
 481         hex "NUMA emulation memory chunk size"
 482         default 0x10000000
 483         range 0x400000 0x100000000
 484         depends on NUMA_EMU
 485         help
 486           Select the default size by which the memory is chopped and then
 487           assigned to emulated NUMA nodes.
 488
 489           This can be overridden by specifying
 490
 491           emu_size=<n>
 492
 493           on the kernel command line where also suffixes K, M, G, and T are
 494           supported.
 495
 496 endmenu
 497
 498 config SCHED_SMT
 499         def_bool n
 500
 501 config SCHED_MC
 502         def_bool n
 503
 504 config SCHED_BOOK
 505         def_bool n
 506
 507 config SCHED_DRAWER
 508         def_bool n
 509
 510 config SCHED_TOPOLOGY
 511         def_bool y
 512         prompt "Topology scheduler support"
 513         depends on SMP
 514         select SCHED_SMT
 515         select SCHED_MC
 516         select SCHED_BOOK
 517         select SCHED_DRAWER
 518         help
 519           Topology scheduler support improves the CPU scheduler's decision
 520           making when dealing with machines that have multi-threading,
 521           multiple cores or multiple books.
 522
 523 source kernel/Kconfig.hz
 524
 525 config KEXEC
 526         def_bool y
 527         select KEXEC_CORE
 528
 529 config KEXEC_FILE
 530         bool "kexec file based system call"
 531         select KEXEC_CORE
 532         select BUILD_BIN2C
 533         depends on CRYPTO
 534         depends on CRYPTO_SHA256
 535         depends on CRYPTO_SHA256_S390
 536         help
 537           Enable the kexec file based system call. In contrast to the normal
 538           kexec system call this system call takes file descriptors for the
 539           kernel and initramfs as arguments.
 540
 541 config ARCH_HAS_KEXEC_PURGATORY
 542         def_bool y
 543         depends on KEXEC_FILE
 544
 545 config ARCH_RANDOM
 546         def_bool y
 547         prompt "s390 architectural random number generation API"
 548         help
 549           Enable the s390 architectural random number generation API
 550           to provide random data for all consumers within the Linux
 551           kernel.
 552
 553           When enabled the arch_random_* functions declared in linux/random.h
 554           are implemented. The implementation is based on the s390 CPACF
 555           instruction subfunction TRNG which provides a real true random
 556           number generator.
 557
 558           If unsure, say Y.
 559
 560 config KERNEL_NOBP
 561         def_bool n
 562         prompt "Enable modified branch prediction for the kernel by default"
 563         help
 564           If this option is selected the kernel will switch to a modified
 565           branch prediction mode if the firmware interface is available.
 566           The modified branch prediction mode improves the behaviour in
 567           regard to speculative execution.
 568
 569           With the option enabled the kernel parameter "nobp=0" or "nospec"
 570           can be used to run the kernel in the normal branch prediction mode.
 571
 572           With the option disabled the modified branch prediction mode is
 573           enabled with the "nobp=1" kernel parameter.
 574
 575           If unsure, say N.
 576
 577 config EXPOLINE
 578         def_bool n
 579         prompt "Avoid speculative indirect branches in the kernel"
 580         help
 581           Compile the kernel with the expoline compiler options to guard
 582           against kernel-to-user data leaks by avoiding speculative indirect
 583           branches.
 584           Requires a compiler with -mindirect-branch=thunk support for full
 585           protection. The kernel may run slower.
 586
 587           If unsure, say N.
 588
 589 choice
 590         prompt "Expoline default"
 591         depends on EXPOLINE
 592         default EXPOLINE_FULL
 593
 594 config EXPOLINE_OFF
 595         bool "spectre_v2=off"
 596
 597 config EXPOLINE_AUTO
 598         bool "spectre_v2=auto"
 599
 600 config EXPOLINE_FULL
 601         bool "spectre_v2=on"
 602
 603 endchoice
 604
 605 endmenu
 606
 607 menu "Memory setup"
 608
 609 config ARCH_SPARSEMEM_ENABLE
 610         def_bool y
 611         select SPARSEMEM_VMEMMAP_ENABLE
 612         select SPARSEMEM_VMEMMAP
 613
 614 config ARCH_SPARSEMEM_DEFAULT
 615         def_bool y
 616
 617 config ARCH_SELECT_MEMORY_MODEL
 618         def_bool y
 619
 620 config ARCH_ENABLE_MEMORY_HOTPLUG
 621         def_bool y if SPARSEMEM
 622
 623 config ARCH_ENABLE_MEMORY_HOTREMOVE
 624         def_bool y
 625
 626 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 627         def_bool y
 628
 629 config FORCE_MAX_ZONEORDER
 630         int
 631         default "9"
 632
 633 config MAX_PHYSMEM_BITS
 634         int "Maximum size of supported physical memory in bits (42-53)"
 635         range 42 53
 636         default "46"
 637         help
 638           This option specifies the maximum supported size of physical memory
 639           in bits. Supported is any size between 2^42 (4TB) and 2^53 (8PB).
 640           Increasing the number of bits also increases the kernel image size.
 641           By default 46 bits (64TB) are supported.
 642
 643 config PACK_STACK
 644         def_bool y
 645         prompt "Pack kernel stack"
 646         help
 647           This option enables the compiler option -mkernel-backchain if it
 648           is available. If the option is available the compiler supports
 649           the new stack layout which dramatically reduces the minimum stack
 650           frame size. With an old compiler a non-leaf function needs a
 651           minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
 652           -mkernel-backchain the minimum size drops to 16 byte on 31 bit
 653           and 24 byte on 64 bit.
 654
 655           Say Y if you are unsure.
 656
 657 config CHECK_STACK
 658         def_bool y
 659         depends on !VMAP_STACK
 660         prompt "Detect kernel stack overflow"
 661         help
 662           This option enables the compiler option -mstack-guard and
 663           -mstack-size if they are available. If the compiler supports them
 664           it will emit additional code to each function prolog to trigger
 665           an illegal operation if the kernel stack is about to overflow.
 666
 667           Say N if you are unsure.
 668
 669 config STACK_GUARD
 670         int "Size of the guard area (128-1024)"
 671         range 128 1024
 672         depends on CHECK_STACK
 673         default "256"
 674         help
 675           This allows you to specify the size of the guard area at the lower
 676           end of the kernel stack. If the kernel stack points into the guard
 677           area on function entry an illegal operation is triggered. The size
 678           needs to be a power of 2. Please keep in mind that the size of an
 679           interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
 680           The minimum size for the stack guard should be 256 for 31 bit and
 681           512 for 64 bit.
 682
 683 config WARN_DYNAMIC_STACK
 684         def_bool n
 685         prompt "Emit compiler warnings for function with dynamic stack usage"
 686         help
 687           This option enables the compiler option -mwarn-dynamicstack. If the
 688           compiler supports this options generates warnings for functions
 689           that dynamically allocate stack space using alloca.
 690
 691           Say N if you are unsure.
 692
 693 endmenu
 694
 695 menu "I/O subsystem"
 696
 697 config QDIO
 698         def_tristate y
 699         prompt "QDIO support"
 700         ---help---
 701           This driver provides the Queued Direct I/O base support for
 702           IBM System z.
 703
 704           To compile this driver as a module, choose M here: the
 705           module will be called qdio.
 706
 707           If unsure, say Y.
 708
 709 menuconfig PCI
 710         bool "PCI support"
 711         select PCI_MSI
 712         select IOMMU_HELPER
 713         select IOMMU_SUPPORT
 714         select NEED_DMA_MAP_STATE
 715         select NEED_SG_DMA_LENGTH
 716
 717         help
 718           Enable PCI support.
 719
 720 if PCI
 721
 722 config PCI_NR_FUNCTIONS
 723         int "Maximum number of PCI functions (1-4096)"
 724         range 1 4096
 725         default "128"
 726         help
 727           This allows you to specify the maximum number of PCI functions which
 728           this kernel will support.
 729
 730 source "drivers/pci/Kconfig"
 731
 732 endif   # PCI
 733
 734 config PCI_DOMAINS
 735         def_bool PCI
 736
 737 config HAS_IOMEM
 738         def_bool PCI
 739
 740 config CHSC_SCH
 741         def_tristate m
 742         prompt "Support for CHSC subchannels"
 743         help
 744           This driver allows usage of CHSC subchannels. A CHSC subchannel
 745           is usually present on LPAR only.
 746           The driver creates a device /dev/chsc, which may be used to
 747           obtain I/O configuration information about the machine and
 748           to issue asynchronous chsc commands (DANGEROUS).
 749           You will usually only want to use this interface on a special
 750           LPAR designated for system management.
 751
 752           To compile this driver as a module, choose M here: the
 753           module will be called chsc_sch.
 754
 755           If unsure, say N.
 756
 757 config SCM_BUS
 758         def_bool y
 759         prompt "SCM bus driver"
 760         help
 761           Bus driver for Storage Class Memory.
 762
 763 config EADM_SCH
 764         def_tristate m
 765         prompt "Support for EADM subchannels"
 766         depends on SCM_BUS
 767         help
 768           This driver allows usage of EADM subchannels. EADM subchannels act
 769           as a communication vehicle for SCM increments.
 770
 771           To compile this driver as a module, choose M here: the
 772           module will be called eadm_sch.
 773
 774 config VFIO_CCW
 775         def_tristate n
 776         prompt "Support for VFIO-CCW subchannels"
 777         depends on S390_CCW_IOMMU && VFIO_MDEV
 778         help
 779           This driver allows usage of I/O subchannels via VFIO-CCW.
 780
 781           To compile this driver as a module, choose M here: the
 782           module will be called vfio_ccw.
 783
 784 config VFIO_AP
 785         def_tristate n
 786         prompt "VFIO support for AP devices"
 787         depends on S390_AP_IOMMU && VFIO_MDEV_DEVICE && KVM
 788         help
 789                 This driver grants access to Adjunct Processor (AP) devices
 790                 via the VFIO mediated device interface.
 791
 792                 To compile this driver as a module, choose M here: the module
 793                 will be called vfio_ap.
 794
 795 endmenu
 796
 797 menu "Dump support"
 798
 799 config CRASH_DUMP
 800         bool "kernel crash dumps"
 801         depends on SMP
 802         select KEXEC
 803         help
 804           Generate crash dump after being started by kexec.
 805           Crash dump kernels are loaded in the main kernel with kexec-tools
 806           into a specially reserved region and then later executed after
 807           a crash by kdump/kexec.
 808           Refer to <file:Documentation/s390/zfcpdump.txt> for more details on this.
 809           This option also enables s390 zfcpdump.
 810           See also <file:Documentation/s390/zfcpdump.txt>
 811
 812 endmenu
 813
 814 config SECCOMP
 815         def_bool y
 816         prompt "Enable seccomp to safely compute untrusted bytecode"
 817         depends on PROC_FS
 818         help
 819           This kernel feature is useful for number crunching applications
 820           that may need to compute untrusted bytecode during their
 821           execution. By using pipes or other transports made available to
 822           the process as file descriptors supporting the read/write
 823           syscalls, it's possible to isolate those applications in
 824           their own address space using seccomp. Once seccomp is
 825           enabled via /proc/<pid>/seccomp, it cannot be disabled
 826           and the task is only allowed to execute a few safe syscalls
 827           defined by each seccomp mode.
 828
 829           If unsure, say Y.
 830
 831 menu "Power Management"
 832
 833 config ARCH_HIBERNATION_POSSIBLE
 834         def_bool y
 835
 836 source "kernel/power/Kconfig"
 837
 838 endmenu
 839
 840 config PCMCIA
 841         def_bool n
 842
 843 config CCW
 844         def_bool y
 845
 846 config HAVE_PNETID
 847         tristate
 848         default (SMC || CCWGROUP)
 849
 850 menu "Virtualization"
 851
 852 config PFAULT
 853         def_bool y
 854         prompt "Pseudo page fault support"
 855         help
 856           Select this option, if you want to use PFAULT pseudo page fault
 857           handling under VM. If running native or in LPAR, this option
 858           has no effect. If your VM does not support PFAULT, PAGEEX
 859           pseudo page fault handling will be used.
 860           Note that VM 4.2 supports PFAULT but has a bug in its
 861           implementation that causes some problems.
 862           Everybody who wants to run Linux under VM != VM4.2 should select
 863           this option.
 864
 865 config CMM
 866         def_tristate n
 867         prompt "Cooperative memory management"
 868         help
 869           Select this option, if you want to enable the kernel interface
 870           to reduce the memory size of the system. This is accomplished
 871           by allocating pages of memory and put them "on hold". This only
 872           makes sense for a system running under VM where the unused pages
 873           will be reused by VM for other guest systems. The interface
 874           allows an external monitor to balance memory of many systems.
 875           Everybody who wants to run Linux under VM should select this
 876           option.
 877
 878 config CMM_IUCV
 879         def_bool y
 880         prompt "IUCV special message interface to cooperative memory management"
 881         depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
 882         help
 883           Select this option to enable the special message interface to
 884           the cooperative memory management.
 885
 886 config APPLDATA_BASE
 887         def_bool n
 888         prompt "Linux - VM Monitor Stream, base infrastructure"
 889         depends on PROC_FS
 890         help
 891           This provides a kernel interface for creating and updating z/VM APPLDATA
 892           monitor records. The monitor records are updated at certain time
 893           intervals, once the timer is started.
 894           Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
 895           i.e. enables or disables monitoring on the Linux side.
 896           A custom interval value (in seconds) can be written to
 897           /proc/appldata/interval.
 898
 899           Defaults are 60 seconds interval and timer off.
 900           The /proc entries can also be read from, showing the current settings.
 901
 902 config APPLDATA_MEM
 903         def_tristate m
 904         prompt "Monitor memory management statistics"
 905         depends on APPLDATA_BASE && VM_EVENT_COUNTERS
 906         help
 907           This provides memory management related data to the Linux - VM Monitor
 908           Stream, like paging/swapping rate, memory utilisation, etc.
 909           Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
 910           APPLDATA monitor record, i.e. enables or disables monitoring this record
 911           on the z/VM side.
 912
 913           Default is disabled.
 914           The /proc entry can also be read from, showing the current settings.
 915
 916           This can also be compiled as a module, which will be called
 917           appldata_mem.o.
 918
 919 config APPLDATA_OS
 920         def_tristate m
 921         prompt "Monitor OS statistics"
 922         depends on APPLDATA_BASE
 923         help
 924           This provides OS related data to the Linux - VM Monitor Stream, like
 925           CPU utilisation, etc.
 926           Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
 927           APPLDATA monitor record, i.e. enables or disables monitoring this record
 928           on the z/VM side.
 929
 930           Default is disabled.
 931           This can also be compiled as a module, which will be called
 932           appldata_os.o.
 933
 934 config APPLDATA_NET_SUM
 935         def_tristate m
 936         prompt "Monitor overall network statistics"
 937         depends on APPLDATA_BASE && NET
 938         help
 939           This provides network related data to the Linux - VM Monitor Stream,
 940           currently there is only a total sum of network I/O statistics, no
 941           per-interface data.
 942           Writing 1 or 0 to /proc/appldata/net_sum 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_net_sum.o.
 949
 950 config S390_HYPFS_FS
 951         def_bool y
 952         prompt "s390 hypervisor file system support"
 953         select SYS_HYPERVISOR
 954         help
 955           This is a virtual file system intended to provide accounting
 956           information in an s390 hypervisor environment.
 957
 958 source "arch/s390/kvm/Kconfig"
 959
 960 config S390_GUEST
 961         def_bool y
 962         prompt "s390 support for virtio devices"
 963         select TTY
 964         select VIRTUALIZATION
 965         select VIRTIO
 966         select VIRTIO_CONSOLE
 967         help
 968           Enabling this option adds support for virtio based paravirtual device
 969           drivers on s390.
 970
 971           Select this option if you want to run the kernel as a guest under
 972           the KVM hypervisor.
 973
 974 endmenu