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 ARCH_DMA_ADDR_T_64BIT
  39         def_bool y
  40
  41 config GENERIC_LOCKBREAK
  42         def_bool y if SMP && PREEMPT
  43
  44 config PGSTE
  45         def_bool y if KVM
  46
  47 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
  48         def_bool y
  49
  50 config KEXEC
  51         def_bool y
  52         select KEXEC_CORE
  53
  54 config AUDIT_ARCH
  55         def_bool y
  56
  57 config NO_IOPORT_MAP
  58         def_bool y
  59
  60 config PCI_QUIRKS
  61         def_bool n
  62
  63 config ARCH_SUPPORTS_UPROBES
  64         def_bool y
  65
  66 config S390
  67         def_bool y
  68         select ARCH_BINFMT_ELF_STATE
  69         select ARCH_HAS_DEVMEM_IS_ALLOWED
  70         select ARCH_HAS_ELF_RANDOMIZE
  71         select ARCH_HAS_FORTIFY_SOURCE
  72         select ARCH_HAS_GCOV_PROFILE_ALL
  73         select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
  74         select ARCH_HAS_KCOV
  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_DEFERRED_STRUCT_PAGE_INIT
 112         select ARCH_SUPPORTS_NUMA_BALANCING
 113         select ARCH_USE_BUILTIN_BSWAP
 114         select ARCH_USE_CMPXCHG_LOCKREF
 115         select ARCH_WANTS_DYNAMIC_TASK_STRUCT
 116         select ARCH_WANTS_PROT_NUMA_PROT_NONE
 117         select ARCH_WANTS_UBSAN_NO_NULL
 118         select ARCH_WANT_IPC_PARSE_VERSION
 119         select BUILDTIME_EXTABLE_SORT
 120         select CLONE_BACKWARDS2
 121         select DYNAMIC_FTRACE if FUNCTION_TRACER
 122         select GENERIC_CLOCKEVENTS
 123         select GENERIC_CPU_AUTOPROBE
 124         select GENERIC_CPU_DEVICES if !SMP
 125         select GENERIC_CPU_VULNERABILITIES
 126         select GENERIC_FIND_FIRST_BIT
 127         select GENERIC_SMP_IDLE_THREAD
 128         select GENERIC_TIME_VSYSCALL
 129         select HAVE_ALIGNED_STRUCT_PAGE if SLUB
 130         select HAVE_ARCH_AUDITSYSCALL
 131         select HAVE_ARCH_JUMP_LABEL
 132         select CPU_NO_EFFICIENT_FFS if !HAVE_MARCH_Z9_109_FEATURES
 133         select HAVE_ARCH_SECCOMP_FILTER
 134         select HAVE_ARCH_SOFT_DIRTY
 135         select HAVE_ARCH_TRACEHOOK
 136         select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 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_API_DEBUG
 143         select HAVE_DMA_CONTIGUOUS
 144         select DMA_NOOP_OPS
 145         select HAVE_DYNAMIC_FTRACE
 146         select HAVE_DYNAMIC_FTRACE_WITH_REGS
 147         select HAVE_EFFICIENT_UNALIGNED_ACCESS
 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_XZ
 159         select HAVE_KPROBES
 160         select HAVE_KRETPROBES
 161         select HAVE_KVM
 162         select HAVE_LIVEPATCH
 163         select HAVE_PERF_REGS
 164         select HAVE_PERF_USER_STACK_DUMP
 165         select HAVE_MEMBLOCK
 166         select HAVE_MEMBLOCK_NODE_MAP
 167         select HAVE_MEMBLOCK_PHYS_MAP
 168         select HAVE_MOD_ARCH_SPECIFIC
 169         select HAVE_OPROFILE
 170         select HAVE_PERF_EVENTS
 171         select HAVE_REGS_AND_STACK_ACCESS_API
 172         select HAVE_SYSCALL_TRACEPOINTS
 173         select HAVE_VIRT_CPU_ACCOUNTING
 174         select MODULES_USE_ELF_RELA
 175         select NO_BOOTMEM
 176         select OLD_SIGACTION
 177         select OLD_SIGSUSPEND3
 178         select SPARSE_IRQ
 179         select SYSCTL_EXCEPTION_TRACE
 180         select THREAD_INFO_IN_TASK
 181         select TTY
 182         select VIRT_CPU_ACCOUNTING
 183         select ARCH_HAS_SCALED_CPUTIME
 184         select VIRT_TO_BUS
 185         select HAVE_NMI
 186
 187
 188 config SCHED_OMIT_FRAME_POINTER
 189         def_bool y
 190
 191 config PGTABLE_LEVELS
 192         int
 193         default 5
 194
 195 source "init/Kconfig"
 196
 197 source "kernel/Kconfig.freezer"
 198
 199 source "kernel/livepatch/Kconfig"
 200
 201 menu "Processor type and features"
 202
 203 config HAVE_MARCH_Z900_FEATURES
 204         def_bool n
 205
 206 config HAVE_MARCH_Z990_FEATURES
 207         def_bool n
 208         select HAVE_MARCH_Z900_FEATURES
 209
 210 config HAVE_MARCH_Z9_109_FEATURES
 211         def_bool n
 212         select HAVE_MARCH_Z990_FEATURES
 213
 214 config HAVE_MARCH_Z10_FEATURES
 215         def_bool n
 216         select HAVE_MARCH_Z9_109_FEATURES
 217
 218 config HAVE_MARCH_Z196_FEATURES
 219         def_bool n
 220         select HAVE_MARCH_Z10_FEATURES
 221
 222 config HAVE_MARCH_ZEC12_FEATURES
 223         def_bool n
 224         select HAVE_MARCH_Z196_FEATURES
 225
 226 config HAVE_MARCH_Z13_FEATURES
 227         def_bool n
 228         select HAVE_MARCH_ZEC12_FEATURES
 229
 230 config HAVE_MARCH_Z14_FEATURES
 231         def_bool n
 232         select HAVE_MARCH_Z13_FEATURES
 233
 234 choice
 235         prompt "Processor type"
 236         default MARCH_Z196
 237
 238 config MARCH_Z900
 239         bool "IBM zSeries model z800 and z900"
 240         select HAVE_MARCH_Z900_FEATURES
 241         help
 242           Select this to enable optimizations for model z800/z900 (2064 and
 243           2066 series). This will enable some optimizations that are not
 244           available on older ESA/390 (31 Bit) only CPUs.
 245
 246 config MARCH_Z990
 247         bool "IBM zSeries model z890 and z990"
 248         select HAVE_MARCH_Z990_FEATURES
 249         help
 250           Select this to enable optimizations for model z890/z990 (2084 and
 251           2086 series). The kernel will be slightly faster but will not work
 252           on older machines.
 253
 254 config MARCH_Z9_109
 255         bool "IBM System z9"
 256         select HAVE_MARCH_Z9_109_FEATURES
 257         help
 258           Select this to enable optimizations for IBM System z9 (2094 and
 259           2096 series). The kernel will be slightly faster but will not work
 260           on older machines.
 261
 262 config MARCH_Z10
 263         bool "IBM System z10"
 264         select HAVE_MARCH_Z10_FEATURES
 265         help
 266           Select this to enable optimizations for IBM System z10 (2097 and
 267           2098 series). The kernel will be slightly faster but will not work
 268           on older machines.
 269
 270 config MARCH_Z196
 271         bool "IBM zEnterprise 114 and 196"
 272         select HAVE_MARCH_Z196_FEATURES
 273         help
 274           Select this to enable optimizations for IBM zEnterprise 114 and 196
 275           (2818 and 2817 series). The kernel will be slightly faster but will
 276           not work on older machines.
 277
 278 config MARCH_ZEC12
 279         bool "IBM zBC12 and zEC12"
 280         select HAVE_MARCH_ZEC12_FEATURES
 281         help
 282           Select this to enable optimizations for IBM zBC12 and zEC12 (2828 and
 283           2827 series). The kernel will be slightly faster but will not work on
 284           older machines.
 285
 286 config MARCH_Z13
 287         bool "IBM z13s and z13"
 288         select HAVE_MARCH_Z13_FEATURES
 289         help
 290           Select this to enable optimizations for IBM z13s and z13 (2965 and
 291           2964 series). The kernel will be slightly faster but will not work on
 292           older machines.
 293
 294 config MARCH_Z14
 295         bool "IBM z14 ZR1 and z14"
 296         select HAVE_MARCH_Z14_FEATURES
 297         help
 298           Select this to enable optimizations for IBM z14 ZR1 and z14 (3907
 299           and 3906 series). The kernel will be slightly faster but will not
 300           work on older machines.
 301
 302 endchoice
 303
 304 config MARCH_Z900_TUNE
 305         def_bool TUNE_Z900 || MARCH_Z900 && TUNE_DEFAULT
 306
 307 config MARCH_Z990_TUNE
 308         def_bool TUNE_Z990 || MARCH_Z990 && TUNE_DEFAULT
 309
 310 config MARCH_Z9_109_TUNE
 311         def_bool TUNE_Z9_109 || MARCH_Z9_109 && TUNE_DEFAULT
 312
 313 config MARCH_Z10_TUNE
 314         def_bool TUNE_Z10 || MARCH_Z10 && TUNE_DEFAULT
 315
 316 config MARCH_Z196_TUNE
 317         def_bool TUNE_Z196 || MARCH_Z196 && TUNE_DEFAULT
 318
 319 config MARCH_ZEC12_TUNE
 320         def_bool TUNE_ZEC12 || MARCH_ZEC12 && TUNE_DEFAULT
 321
 322 config MARCH_Z13_TUNE
 323         def_bool TUNE_Z13 || MARCH_Z13 && TUNE_DEFAULT
 324
 325 config MARCH_Z14_TUNE
 326         def_bool TUNE_Z14 || MARCH_Z14 && TUNE_DEFAULT
 327
 328 choice
 329         prompt "Tune code generation"
 330         default TUNE_DEFAULT
 331         help
 332           Cause the compiler to tune (-mtune) the generated code for a machine.
 333           This will make the code run faster on the selected machine but
 334           somewhat slower on other machines.
 335           This option only changes how the compiler emits instructions, not the
 336           selection of instructions itself, so the resulting kernel will run on
 337           all other machines.
 338
 339 config TUNE_DEFAULT
 340         bool "Default"
 341         help
 342           Tune the generated code for the target processor for which the kernel
 343           will be compiled.
 344
 345 config TUNE_Z900
 346         bool "IBM zSeries model z800 and z900"
 347
 348 config TUNE_Z990
 349         bool "IBM zSeries model z890 and z990"
 350
 351 config TUNE_Z9_109
 352         bool "IBM System z9"
 353
 354 config TUNE_Z10
 355         bool "IBM System z10"
 356
 357 config TUNE_Z196
 358         bool "IBM zEnterprise 114 and 196"
 359
 360 config TUNE_ZEC12
 361         bool "IBM zBC12 and zEC12"
 362
 363 config TUNE_Z13
 364         bool "IBM z13"
 365
 366 config TUNE_Z14
 367         bool "IBM z14"
 368
 369 endchoice
 370
 371 config 64BIT
 372         def_bool y
 373
 374 config COMPAT
 375         def_bool y
 376         prompt "Kernel support for 31 bit emulation"
 377         select COMPAT_BINFMT_ELF if BINFMT_ELF
 378         select ARCH_WANT_OLD_COMPAT_IPC
 379         select COMPAT_OLD_SIGACTION
 380         depends on MULTIUSER
 381         help
 382           Select this option if you want to enable your system kernel to
 383           handle system-calls from ELF binaries for 31 bit ESA.  This option
 384           (and some other stuff like libraries and such) is needed for
 385           executing 31 bit applications.  It is safe to say "Y".
 386
 387 config SYSVIPC_COMPAT
 388         def_bool y if COMPAT && SYSVIPC
 389
 390 config SMP
 391         def_bool y
 392         prompt "Symmetric multi-processing support"
 393         ---help---
 394           This enables support for systems with more than one CPU. If you have
 395           a system with only one CPU, like most personal computers, say N. If
 396           you have a system with more than one CPU, say Y.
 397
 398           If you say N here, the kernel will run on uni- and multiprocessor
 399           machines, but will use only one CPU of a multiprocessor machine. If
 400           you say Y here, the kernel will run on many, but not all,
 401           uniprocessor machines. On a uniprocessor machine, the kernel
 402           will run faster if you say N here.
 403
 404           See also the SMP-HOWTO available at
 405           <http://www.tldp.org/docs.html#howto>.
 406
 407           Even if you don't know what to do here, say Y.
 408
 409 config NR_CPUS
 410         int "Maximum number of CPUs (2-512)"
 411         range 2 512
 412         depends on SMP
 413         default "64"
 414         help
 415           This allows you to specify the maximum number of CPUs which this
 416           kernel will support. The maximum supported value is 512 and the
 417           minimum value which makes sense is 2.
 418
 419           This is purely to save memory - each supported CPU adds
 420           approximately sixteen kilobytes to the kernel image.
 421
 422 config HOTPLUG_CPU
 423         def_bool y
 424         prompt "Support for hot-pluggable CPUs"
 425         depends on SMP
 426         help
 427           Say Y here to be able to turn CPUs off and on. CPUs
 428           can be controlled through /sys/devices/system/cpu/cpu#.
 429           Say N if you want to disable CPU hotplug.
 430
 431 # Some NUMA nodes have memory ranges that span
 432 # other nodes.  Even though a pfn is valid and
 433 # between a node's start and end pfns, it may not
 434 # reside on that node.  See memmap_init_zone()
 435 # for details. <- They meant memory holes!
 436 config NODES_SPAN_OTHER_NODES
 437         def_bool NUMA
 438
 439 config NUMA
 440         bool "NUMA support"
 441         depends on SMP && SCHED_TOPOLOGY
 442         default n
 443         help
 444           Enable NUMA support
 445
 446           This option adds NUMA support to the kernel.
 447
 448           An operation mode can be selected by appending
 449           numa=<method> to the kernel command line.
 450
 451           The default behaviour is identical to appending numa=plain to
 452           the command line. This will create just one node with all
 453           available memory and all CPUs in it.
 454
 455 config NODES_SHIFT
 456         int "Maximum NUMA nodes (as a power of 2)"
 457         range 1 10
 458         depends on NUMA
 459         default "4"
 460         help
 461           Specify the maximum number of NUMA nodes available on the target
 462           system. Increases memory reserved to accommodate various tables.
 463
 464 menu "Select NUMA modes"
 465         depends on NUMA
 466
 467 config NUMA_EMU
 468         bool "NUMA emulation"
 469         default y
 470         help
 471           Numa emulation mode will split the available system memory into
 472           equal chunks which then are distributed over the configured number
 473           of nodes in a round-robin manner.
 474
 475           The number of fake nodes is limited by the number of available memory
 476           chunks (i.e. memory size / fake size) and the number of supported
 477           nodes in the kernel.
 478
 479           The CPUs are assigned to the nodes in a way that partially respects
 480           the original machine topology (if supported by the machine).
 481           Fair distribution of the CPUs is not guaranteed.
 482
 483 config EMU_SIZE
 484         hex "NUMA emulation memory chunk size"
 485         default 0x10000000
 486         range 0x400000 0x100000000
 487         depends on NUMA_EMU
 488         help
 489           Select the default size by which the memory is chopped and then
 490           assigned to emulated NUMA nodes.
 491
 492           This can be overridden by specifying
 493
 494           emu_size=<n>
 495
 496           on the kernel command line where also suffixes K, M, G, and T are
 497           supported.
 498
 499 endmenu
 500
 501 config SCHED_SMT
 502         def_bool n
 503
 504 config SCHED_MC
 505         def_bool n
 506
 507 config SCHED_BOOK
 508         def_bool n
 509
 510 config SCHED_DRAWER
 511         def_bool n
 512
 513 config SCHED_TOPOLOGY
 514         def_bool y
 515         prompt "Topology scheduler support"
 516         depends on SMP
 517         select SCHED_SMT
 518         select SCHED_MC
 519         select SCHED_BOOK
 520         select SCHED_DRAWER
 521         help
 522           Topology scheduler support improves the CPU scheduler's decision
 523           making when dealing with machines that have multi-threading,
 524           multiple cores or multiple books.
 525
 526 source kernel/Kconfig.preempt
 527
 528 source kernel/Kconfig.hz
 529
 530 config ARCH_RANDOM
 531         def_bool y
 532         prompt "s390 architectural random number generation API"
 533         help
 534           Enable the s390 architectural random number generation API
 535           to provide random data for all consumers within the Linux
 536           kernel.
 537
 538           When enabled the arch_random_* functions declared in linux/random.h
 539           are implemented. The implementation is based on the s390 CPACF
 540           instruction subfunction TRNG which provides a real true random
 541           number generator.
 542
 543           If unsure, say Y.
 544
 545 config KERNEL_NOBP
 546         def_bool n
 547         prompt "Enable modified branch prediction for the kernel by default"
 548         help
 549           If this option is selected the kernel will switch to a modified
 550           branch prediction mode if the firmware interface is available.
 551           The modified branch prediction mode improves the behaviour in
 552           regard to speculative execution.
 553
 554           With the option enabled the kernel parameter "nobp=0" or "nospec"
 555           can be used to run the kernel in the normal branch prediction mode.
 556
 557           With the option disabled the modified branch prediction mode is
 558           enabled with the "nobp=1" kernel parameter.
 559
 560           If unsure, say N.
 561
 562 config EXPOLINE
 563         def_bool n
 564         prompt "Avoid speculative indirect branches in the kernel"
 565         help
 566           Compile the kernel with the expoline compiler options to guard
 567           against kernel-to-user data leaks by avoiding speculative indirect
 568           branches.
 569           Requires a compiler with -mindirect-branch=thunk support for full
 570           protection. The kernel may run slower.
 571
 572           If unsure, say N.
 573
 574 choice
 575         prompt "Expoline default"
 576         depends on EXPOLINE
 577         default EXPOLINE_FULL
 578
 579 config EXPOLINE_OFF
 580         bool "spectre_v2=off"
 581
 582 config EXPOLINE_AUTO
 583         bool "spectre_v2=auto"
 584
 585 config EXPOLINE_FULL
 586         bool "spectre_v2=on"
 587
 588 endchoice
 589
 590 endmenu
 591
 592 menu "Memory setup"
 593
 594 config ARCH_SPARSEMEM_ENABLE
 595         def_bool y
 596         select SPARSEMEM_VMEMMAP_ENABLE
 597         select SPARSEMEM_VMEMMAP
 598
 599 config ARCH_SPARSEMEM_DEFAULT
 600         def_bool y
 601
 602 config ARCH_SELECT_MEMORY_MODEL
 603         def_bool y
 604
 605 config ARCH_ENABLE_MEMORY_HOTPLUG
 606         def_bool y if SPARSEMEM
 607
 608 config ARCH_ENABLE_MEMORY_HOTREMOVE
 609         def_bool y
 610
 611 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 612         def_bool y
 613
 614 config FORCE_MAX_ZONEORDER
 615         int
 616         default "9"
 617
 618 source "mm/Kconfig"
 619
 620 config MAX_PHYSMEM_BITS
 621         int "Maximum size of supported physical memory in bits (42-53)"
 622         range 42 53
 623         default "46"
 624         help
 625           This option specifies the maximum supported size of physical memory
 626           in bits. Supported is any size between 2^42 (4TB) and 2^53 (8PB).
 627           Increasing the number of bits also increases the kernel image size.
 628           By default 46 bits (64TB) are supported.
 629
 630 config PACK_STACK
 631         def_bool y
 632         prompt "Pack kernel stack"
 633         help
 634           This option enables the compiler option -mkernel-backchain if it
 635           is available. If the option is available the compiler supports
 636           the new stack layout which dramatically reduces the minimum stack
 637           frame size. With an old compiler a non-leaf function needs a
 638           minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
 639           -mkernel-backchain the minimum size drops to 16 byte on 31 bit
 640           and 24 byte on 64 bit.
 641
 642           Say Y if you are unsure.
 643
 644 config CHECK_STACK
 645         def_bool y
 646         prompt "Detect kernel stack overflow"
 647         help
 648           This option enables the compiler option -mstack-guard and
 649           -mstack-size if they are available. If the compiler supports them
 650           it will emit additional code to each function prolog to trigger
 651           an illegal operation if the kernel stack is about to overflow.
 652
 653           Say N if you are unsure.
 654
 655 config STACK_GUARD
 656         int "Size of the guard area (128-1024)"
 657         range 128 1024
 658         depends on CHECK_STACK
 659         default "256"
 660         help
 661           This allows you to specify the size of the guard area at the lower
 662           end of the kernel stack. If the kernel stack points into the guard
 663           area on function entry an illegal operation is triggered. The size
 664           needs to be a power of 2. Please keep in mind that the size of an
 665           interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
 666           The minimum size for the stack guard should be 256 for 31 bit and
 667           512 for 64 bit.
 668
 669 config WARN_DYNAMIC_STACK
 670         def_bool n
 671         prompt "Emit compiler warnings for function with dynamic stack usage"
 672         help
 673           This option enables the compiler option -mwarn-dynamicstack. If the
 674           compiler supports this options generates warnings for functions
 675           that dynamically allocate stack space using alloca.
 676
 677           Say N if you are unsure.
 678
 679 endmenu
 680
 681 menu "I/O subsystem"
 682
 683 config QDIO
 684         def_tristate y
 685         prompt "QDIO support"
 686         ---help---
 687           This driver provides the Queued Direct I/O base support for
 688           IBM System z.
 689
 690           To compile this driver as a module, choose M here: the
 691           module will be called qdio.
 692
 693           If unsure, say Y.
 694
 695 menuconfig PCI
 696         bool "PCI support"
 697         select PCI_MSI
 698         select IOMMU_SUPPORT
 699         help
 700           Enable PCI support.
 701
 702 if PCI
 703
 704 config PCI_NR_FUNCTIONS
 705         int "Maximum number of PCI functions (1-4096)"
 706         range 1 4096
 707         default "128"
 708         help
 709           This allows you to specify the maximum number of PCI functions which
 710           this kernel will support.
 711
 712 source "drivers/pci/Kconfig"
 713
 714 endif   # PCI
 715
 716 config PCI_DOMAINS
 717         def_bool PCI
 718
 719 config HAS_IOMEM
 720         def_bool PCI
 721
 722 config IOMMU_HELPER
 723         def_bool PCI
 724
 725 config NEED_SG_DMA_LENGTH
 726         def_bool PCI
 727
 728 config NEED_DMA_MAP_STATE
 729         def_bool PCI
 730
 731 config CHSC_SCH
 732         def_tristate m
 733         prompt "Support for CHSC subchannels"
 734         help
 735           This driver allows usage of CHSC subchannels. A CHSC subchannel
 736           is usually present on LPAR only.
 737           The driver creates a device /dev/chsc, which may be used to
 738           obtain I/O configuration information about the machine and
 739           to issue asynchronous chsc commands (DANGEROUS).
 740           You will usually only want to use this interface on a special
 741           LPAR designated for system management.
 742
 743           To compile this driver as a module, choose M here: the
 744           module will be called chsc_sch.
 745
 746           If unsure, say N.
 747
 748 config SCM_BUS
 749         def_bool y
 750         prompt "SCM bus driver"
 751         help
 752           Bus driver for Storage Class Memory.
 753
 754 config EADM_SCH
 755         def_tristate m
 756         prompt "Support for EADM subchannels"
 757         depends on SCM_BUS
 758         help
 759           This driver allows usage of EADM subchannels. EADM subchannels act
 760           as a communication vehicle for SCM increments.
 761
 762           To compile this driver as a module, choose M here: the
 763           module will be called eadm_sch.
 764
 765 config VFIO_CCW
 766         def_tristate n
 767         prompt "Support for VFIO-CCW subchannels"
 768         depends on S390_CCW_IOMMU && VFIO_MDEV
 769         help
 770           This driver allows usage of I/O subchannels via VFIO-CCW.
 771
 772           To compile this driver as a module, choose M here: the
 773           module will be called vfio_ccw.
 774
 775 endmenu
 776
 777 menu "Dump support"
 778
 779 config CRASH_DUMP
 780         bool "kernel crash dumps"
 781         depends on SMP
 782         select KEXEC
 783         help
 784           Generate crash dump after being started by kexec.
 785           Crash dump kernels are loaded in the main kernel with kexec-tools
 786           into a specially reserved region and then later executed after
 787           a crash by kdump/kexec.
 788           Refer to <file:Documentation/s390/zfcpdump.txt> for more details on this.
 789           This option also enables s390 zfcpdump.
 790           See also <file:Documentation/s390/zfcpdump.txt>
 791
 792 endmenu
 793
 794 menu "Executable file formats / Emulations"
 795
 796 source "fs/Kconfig.binfmt"
 797
 798 config SECCOMP
 799         def_bool y
 800         prompt "Enable seccomp to safely compute untrusted bytecode"
 801         depends on PROC_FS
 802         help
 803           This kernel feature is useful for number crunching applications
 804           that may need to compute untrusted bytecode during their
 805           execution. By using pipes or other transports made available to
 806           the process as file descriptors supporting the read/write
 807           syscalls, it's possible to isolate those applications in
 808           their own address space using seccomp. Once seccomp is
 809           enabled via /proc/<pid>/seccomp, it cannot be disabled
 810           and the task is only allowed to execute a few safe syscalls
 811           defined by each seccomp mode.
 812
 813           If unsure, say Y.
 814
 815 endmenu
 816
 817 menu "Power Management"
 818
 819 config ARCH_HIBERNATION_POSSIBLE
 820         def_bool y
 821
 822 source "kernel/power/Kconfig"
 823
 824 endmenu
 825
 826 source "net/Kconfig"
 827
 828 config PCMCIA
 829         def_bool n
 830
 831 config CCW
 832         def_bool y
 833
 834 source "drivers/Kconfig"
 835
 836 source "fs/Kconfig"
 837
 838 source "arch/s390/Kconfig.debug"
 839
 840 source "security/Kconfig"
 841
 842 source "crypto/Kconfig"
 843
 844 source "lib/Kconfig"
 845
 846 menu "Virtualization"
 847
 848 config PFAULT
 849         def_bool y
 850         prompt "Pseudo page fault support"
 851         help
 852           Select this option, if you want to use PFAULT pseudo page fault
 853           handling under VM. If running native or in LPAR, this option
 854           has no effect. If your VM does not support PFAULT, PAGEEX
 855           pseudo page fault handling will be used.
 856           Note that VM 4.2 supports PFAULT but has a bug in its
 857           implementation that causes some problems.
 858           Everybody who wants to run Linux under VM != VM4.2 should select
 859           this option.
 860
 861 config CMM
 862         def_tristate n
 863         prompt "Cooperative memory management"
 864         help
 865           Select this option, if you want to enable the kernel interface
 866           to reduce the memory size of the system. This is accomplished
 867           by allocating pages of memory and put them "on hold". This only
 868           makes sense for a system running under VM where the unused pages
 869           will be reused by VM for other guest systems. The interface
 870           allows an external monitor to balance memory of many systems.
 871           Everybody who wants to run Linux under VM should select this
 872           option.
 873
 874 config CMM_IUCV
 875         def_bool y
 876         prompt "IUCV special message interface to cooperative memory management"
 877         depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
 878         help
 879           Select this option to enable the special message interface to
 880           the cooperative memory management.
 881
 882 config APPLDATA_BASE
 883         def_bool n
 884         prompt "Linux - VM Monitor Stream, base infrastructure"
 885         depends on PROC_FS
 886         help
 887           This provides a kernel interface for creating and updating z/VM APPLDATA
 888           monitor records. The monitor records are updated at certain time
 889           intervals, once the timer is started.
 890           Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
 891           i.e. enables or disables monitoring on the Linux side.
 892           A custom interval value (in seconds) can be written to
 893           /proc/appldata/interval.
 894
 895           Defaults are 60 seconds interval and timer off.
 896           The /proc entries can also be read from, showing the current settings.
 897
 898 config APPLDATA_MEM
 899         def_tristate m
 900         prompt "Monitor memory management statistics"
 901         depends on APPLDATA_BASE && VM_EVENT_COUNTERS
 902         help
 903           This provides memory management related data to the Linux - VM Monitor
 904           Stream, like paging/swapping rate, memory utilisation, etc.
 905           Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
 906           APPLDATA monitor record, i.e. enables or disables monitoring this record
 907           on the z/VM side.
 908
 909           Default is disabled.
 910           The /proc entry can also be read from, showing the current settings.
 911
 912           This can also be compiled as a module, which will be called
 913           appldata_mem.o.
 914
 915 config APPLDATA_OS
 916         def_tristate m
 917         prompt "Monitor OS statistics"
 918         depends on APPLDATA_BASE
 919         help
 920           This provides OS related data to the Linux - VM Monitor Stream, like
 921           CPU utilisation, etc.
 922           Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
 923           APPLDATA monitor record, i.e. enables or disables monitoring this record
 924           on the z/VM side.
 925
 926           Default is disabled.
 927           This can also be compiled as a module, which will be called
 928           appldata_os.o.
 929
 930 config APPLDATA_NET_SUM
 931         def_tristate m
 932         prompt "Monitor overall network statistics"
 933         depends on APPLDATA_BASE && NET
 934         help
 935           This provides network related data to the Linux - VM Monitor Stream,
 936           currently there is only a total sum of network I/O statistics, no
 937           per-interface data.
 938           Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
 939           APPLDATA monitor record, i.e. enables or disables monitoring this record
 940           on the z/VM side.
 941
 942           Default is disabled.
 943           This can also be compiled as a module, which will be called
 944           appldata_net_sum.o.
 945
 946 config S390_HYPFS_FS
 947         def_bool y
 948         prompt "s390 hypervisor file system support"
 949         select SYS_HYPERVISOR
 950         help
 951           This is a virtual file system intended to provide accounting
 952           information in an s390 hypervisor environment.
 953
 954 source "arch/s390/kvm/Kconfig"
 955
 956 config S390_GUEST
 957         def_bool y
 958         prompt "s390 support for virtio devices"
 959         select TTY
 960         select VIRTUALIZATION
 961         select VIRTIO
 962         select VIRTIO_CONSOLE
 963         help
 964           Enabling this option adds support for virtio based paravirtual device
 965           drivers on s390.
 966
 967           Select this option if you want to run the kernel as a guest under
 968           the KVM hypervisor.
 969
 970 endmenu
 971
 972 config KMSG_IDS
 973         def_bool y
 974         prompt "Kernel message numbers"
 975         help
 976           Select this option if you want to include a message number to the
 977           prefix for kernel messages issued by the s390 architecture and
 978           driver code. See "Documentation/s390/kmsg.txt" for more details.