arch/s390/Kconfig

   1 config MMU
   2         def_bool y
   3
   4 config ZONE_DMA
   5         def_bool y
   6
   7 config LOCKDEP_SUPPORT
   8         def_bool y
   9
  10 config STACKTRACE_SUPPORT
  11         def_bool y
  12
  13 config HAVE_LATENCYTOP_SUPPORT
  14         def_bool y
  15
  16 config RWSEM_GENERIC_SPINLOCK
  17         bool
  18
  19 config RWSEM_XCHGADD_ALGORITHM
  20         def_bool y
  21
  22 config ARCH_HAS_ILOG2_U32
  23         def_bool n
  24
  25 config ARCH_HAS_ILOG2_U64
  26         def_bool n
  27
  28 config GENERIC_HWEIGHT
  29         def_bool y
  30
  31 config GENERIC_BUG
  32         def_bool y if BUG
  33
  34 config GENERIC_BUG_RELATIVE_POINTERS
  35         def_bool y
  36
  37 config NO_IOMEM
  38         def_bool y
  39
  40 config NO_DMA
  41         def_bool y
  42
  43 config ARCH_DMA_ADDR_T_64BIT
  44         def_bool 64BIT
  45
  46 config GENERIC_LOCKBREAK
  47         def_bool y if SMP && PREEMPT
  48
  49 config PGSTE
  50         def_bool y if KVM
  51
  52 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
  53         def_bool y
  54
  55 config KEXEC
  56         def_bool y
  57
  58 config AUDIT_ARCH
  59         def_bool y
  60
  61 config S390
  62         def_bool y
  63         select USE_GENERIC_SMP_HELPERS if SMP
  64         select GENERIC_CPU_DEVICES if !SMP
  65         select HAVE_SYSCALL_WRAPPERS
  66         select HAVE_FUNCTION_TRACER
  67         select HAVE_FUNCTION_TRACE_MCOUNT_TEST
  68         select HAVE_FTRACE_MCOUNT_RECORD
  69         select HAVE_C_RECORDMCOUNT
  70         select HAVE_SYSCALL_TRACEPOINTS
  71         select SYSCTL_EXCEPTION_TRACE
  72         select HAVE_DYNAMIC_FTRACE
  73         select HAVE_FUNCTION_GRAPH_TRACER
  74         select HAVE_REGS_AND_STACK_ACCESS_API
  75         select HAVE_OPROFILE
  76         select HAVE_KPROBES
  77         select HAVE_KRETPROBES
  78         select HAVE_KVM if 64BIT
  79         select HAVE_ARCH_TRACEHOOK
  80         select INIT_ALL_POSSIBLE
  81         select HAVE_IRQ_WORK
  82         select HAVE_PERF_EVENTS
  83         select ARCH_HAVE_NMI_SAFE_CMPXCHG
  84         select HAVE_DEBUG_KMEMLEAK
  85         select HAVE_KERNEL_GZIP
  86         select HAVE_KERNEL_BZIP2
  87         select HAVE_KERNEL_LZMA
  88         select HAVE_KERNEL_LZO
  89         select HAVE_KERNEL_XZ
  90         select HAVE_ARCH_MUTEX_CPU_RELAX
  91         select HAVE_ARCH_JUMP_LABEL if !MARCH_G5
  92         select HAVE_BPF_JIT if 64BIT && PACK_STACK
  93         select ARCH_SAVE_PAGE_KEYS if HIBERNATION
  94         select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
  95         select HAVE_MEMBLOCK
  96         select HAVE_MEMBLOCK_NODE_MAP
  97         select HAVE_CMPXCHG_LOCAL
  98         select HAVE_CMPXCHG_DOUBLE
  99         select HAVE_VIRT_CPU_ACCOUNTING
 100         select VIRT_CPU_ACCOUNTING
 101         select ARCH_DISCARD_MEMBLOCK
 102         select BUILDTIME_EXTABLE_SORT
 103         select ARCH_INLINE_SPIN_TRYLOCK
 104         select ARCH_INLINE_SPIN_TRYLOCK_BH
 105         select ARCH_INLINE_SPIN_LOCK
 106         select ARCH_INLINE_SPIN_LOCK_BH
 107         select ARCH_INLINE_SPIN_LOCK_IRQ
 108         select ARCH_INLINE_SPIN_LOCK_IRQSAVE
 109         select ARCH_INLINE_SPIN_UNLOCK
 110         select ARCH_INLINE_SPIN_UNLOCK_BH
 111         select ARCH_INLINE_SPIN_UNLOCK_IRQ
 112         select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE
 113         select ARCH_INLINE_READ_TRYLOCK
 114         select ARCH_INLINE_READ_LOCK
 115         select ARCH_INLINE_READ_LOCK_BH
 116         select ARCH_INLINE_READ_LOCK_IRQ
 117         select ARCH_INLINE_READ_LOCK_IRQSAVE
 118         select ARCH_INLINE_READ_UNLOCK
 119         select ARCH_INLINE_READ_UNLOCK_BH
 120         select ARCH_INLINE_READ_UNLOCK_IRQ
 121         select ARCH_INLINE_READ_UNLOCK_IRQRESTORE
 122         select ARCH_INLINE_WRITE_TRYLOCK
 123         select ARCH_INLINE_WRITE_LOCK
 124         select ARCH_INLINE_WRITE_LOCK_BH
 125         select ARCH_INLINE_WRITE_LOCK_IRQ
 126         select ARCH_INLINE_WRITE_LOCK_IRQSAVE
 127         select ARCH_INLINE_WRITE_UNLOCK
 128         select ARCH_INLINE_WRITE_UNLOCK_BH
 129         select ARCH_INLINE_WRITE_UNLOCK_IRQ
 130         select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
 131         select HAVE_UID16 if 32BIT
 132         select ARCH_WANT_IPC_PARSE_VERSION
 133         select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT
 134         select GENERIC_SMP_IDLE_THREAD
 135         select GENERIC_TIME_VSYSCALL_OLD
 136         select GENERIC_CLOCKEVENTS
 137         select KTIME_SCALAR if 32BIT
 138         select HAVE_ARCH_SECCOMP_FILTER
 139         select GENERIC_KERNEL_THREAD
 140         select HAVE_MOD_ARCH_SPECIFIC
 141         select MODULES_USE_ELF_RELA
 142
 143 config SCHED_OMIT_FRAME_POINTER
 144         def_bool y
 145
 146 source "init/Kconfig"
 147
 148 source "kernel/Kconfig.freezer"
 149
 150 menu "Processor type and features"
 151
 152 config HAVE_MARCH_Z900_FEATURES
 153         def_bool n
 154
 155 config HAVE_MARCH_Z990_FEATURES
 156         def_bool n
 157         select HAVE_MARCH_Z900_FEATURES
 158
 159 config HAVE_MARCH_Z9_109_FEATURES
 160         def_bool n
 161         select HAVE_MARCH_Z990_FEATURES
 162
 163 config HAVE_MARCH_Z10_FEATURES
 164         def_bool n
 165         select HAVE_MARCH_Z9_109_FEATURES
 166
 167 config HAVE_MARCH_Z196_FEATURES
 168         def_bool n
 169         select HAVE_MARCH_Z10_FEATURES
 170
 171 choice
 172         prompt "Processor type"
 173         default MARCH_G5
 174
 175 config MARCH_G5
 176         bool "System/390 model G5 and G6"
 177         depends on !64BIT
 178         help
 179           Select this to build a 31 bit kernel that works
 180           on all ESA/390 and z/Architecture machines.
 181
 182 config MARCH_Z900
 183         bool "IBM zSeries model z800 and z900"
 184         select HAVE_MARCH_Z900_FEATURES if 64BIT
 185         help
 186           Select this to enable optimizations for model z800/z900 (2064 and
 187           2066 series). This will enable some optimizations that are not
 188           available on older ESA/390 (31 Bit) only CPUs.
 189
 190 config MARCH_Z990
 191         bool "IBM zSeries model z890 and z990"
 192         select HAVE_MARCH_Z990_FEATURES if 64BIT
 193         help
 194           Select this to enable optimizations for model z890/z990 (2084 and
 195           2086 series). The kernel will be slightly faster but will not work
 196           on older machines.
 197
 198 config MARCH_Z9_109
 199         bool "IBM System z9"
 200         select HAVE_MARCH_Z9_109_FEATURES if 64BIT
 201         help
 202           Select this to enable optimizations for IBM System z9 (2094 and
 203           2096 series). The kernel will be slightly faster but will not work
 204           on older machines.
 205
 206 config MARCH_Z10
 207         bool "IBM System z10"
 208         select HAVE_MARCH_Z10_FEATURES if 64BIT
 209         help
 210           Select this to enable optimizations for IBM System z10 (2097 and
 211           2098 series). The kernel will be slightly faster but will not work
 212           on older machines.
 213
 214 config MARCH_Z196
 215         bool "IBM zEnterprise 114 and 196"
 216         select HAVE_MARCH_Z196_FEATURES if 64BIT
 217         help
 218           Select this to enable optimizations for IBM zEnterprise 114 and 196
 219           (2818 and 2817 series). The kernel will be slightly faster but will
 220           not work on older machines.
 221
 222 endchoice
 223
 224 config 64BIT
 225         def_bool y
 226         prompt "64 bit kernel"
 227         help
 228           Select this option if you have an IBM z/Architecture machine
 229           and want to use the 64 bit addressing mode.
 230
 231 config 32BIT
 232         def_bool y if !64BIT
 233
 234 config COMPAT
 235         def_bool y
 236         prompt "Kernel support for 31 bit emulation"
 237         depends on 64BIT
 238         select COMPAT_BINFMT_ELF if BINFMT_ELF
 239         select ARCH_WANT_OLD_COMPAT_IPC
 240         help
 241           Select this option if you want to enable your system kernel to
 242           handle system-calls from ELF binaries for 31 bit ESA.  This option
 243           (and some other stuff like libraries and such) is needed for
 244           executing 31 bit applications.  It is safe to say "Y".
 245
 246 config SYSVIPC_COMPAT
 247         def_bool y if COMPAT && SYSVIPC
 248
 249 config KEYS_COMPAT
 250         def_bool y if COMPAT && KEYS
 251
 252 config SMP
 253         def_bool y
 254         prompt "Symmetric multi-processing support"
 255         ---help---
 256           This enables support for systems with more than one CPU. If you have
 257           a system with only one CPU, like most personal computers, say N. If
 258           you have a system with more than one CPU, say Y.
 259
 260           If you say N here, the kernel will run on single and multiprocessor
 261           machines, but will use only one CPU of a multiprocessor machine. If
 262           you say Y here, the kernel will run on many, but not all,
 263           singleprocessor machines. On a singleprocessor machine, the kernel
 264           will run faster if you say N here.
 265
 266           See also the SMP-HOWTO available at
 267           <http://www.tldp.org/docs.html#howto>.
 268
 269           Even if you don't know what to do here, say Y.
 270
 271 config NR_CPUS
 272         int "Maximum number of CPUs (2-64)"
 273         range 2 64
 274         depends on SMP
 275         default "32" if !64BIT
 276         default "64" if 64BIT
 277         help
 278           This allows you to specify the maximum number of CPUs which this
 279           kernel will support.  The maximum supported value is 64 and the
 280           minimum value which makes sense is 2.
 281
 282           This is purely to save memory - each supported CPU adds
 283           approximately sixteen kilobytes to the kernel image.
 284
 285 config HOTPLUG_CPU
 286         def_bool y
 287         prompt "Support for hot-pluggable CPUs"
 288         depends on SMP
 289         select HOTPLUG
 290         help
 291           Say Y here to be able to turn CPUs off and on. CPUs
 292           can be controlled through /sys/devices/system/cpu/cpu#.
 293           Say N if you want to disable CPU hotplug.
 294
 295 config SCHED_MC
 296         def_bool n
 297
 298 config SCHED_BOOK
 299         def_bool y
 300         prompt "Book scheduler support"
 301         depends on SMP
 302         select SCHED_MC
 303         help
 304           Book scheduler support improves the CPU scheduler's decision making
 305           when dealing with machines that have several books.
 306
 307 source kernel/Kconfig.preempt
 308
 309 config MATHEMU
 310         def_bool y
 311         prompt "IEEE FPU emulation"
 312         depends on MARCH_G5
 313         help
 314           This option is required for IEEE compliant floating point arithmetic
 315           on older ESA/390 machines. Say Y unless you know your machine doesn't
 316           need this.
 317
 318 source kernel/Kconfig.hz
 319
 320 endmenu
 321
 322 menu "Memory setup"
 323
 324 config ARCH_SPARSEMEM_ENABLE
 325         def_bool y
 326         select SPARSEMEM_VMEMMAP_ENABLE
 327         select SPARSEMEM_VMEMMAP
 328         select SPARSEMEM_STATIC if !64BIT
 329
 330 config ARCH_SPARSEMEM_DEFAULT
 331         def_bool y
 332
 333 config ARCH_SELECT_MEMORY_MODEL
 334         def_bool y
 335
 336 config ARCH_ENABLE_MEMORY_HOTPLUG
 337         def_bool y if SPARSEMEM
 338
 339 config ARCH_ENABLE_MEMORY_HOTREMOVE
 340         def_bool y
 341
 342 config FORCE_MAX_ZONEORDER
 343         int
 344         default "9"
 345
 346 source "mm/Kconfig"
 347
 348 config PACK_STACK
 349         def_bool y
 350         prompt "Pack kernel stack"
 351         help
 352           This option enables the compiler option -mkernel-backchain if it
 353           is available. If the option is available the compiler supports
 354           the new stack layout which dramatically reduces the minimum stack
 355           frame size. With an old compiler a non-leaf function needs a
 356           minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
 357           -mkernel-backchain the minimum size drops to 16 byte on 31 bit
 358           and 24 byte on 64 bit.
 359
 360           Say Y if you are unsure.
 361
 362 config SMALL_STACK
 363         def_bool n
 364         prompt "Use 8kb for kernel stack instead of 16kb"
 365         depends on PACK_STACK && 64BIT && !LOCKDEP
 366         help
 367           If you say Y here and the compiler supports the -mkernel-backchain
 368           option the kernel will use a smaller kernel stack size. The reduced
 369           size is 8kb instead of 16kb. This allows to run more threads on a
 370           system and reduces the pressure on the memory management for higher
 371           order page allocations.
 372
 373           Say N if you are unsure.
 374
 375 config CHECK_STACK
 376         def_bool y
 377         prompt "Detect kernel stack overflow"
 378         help
 379           This option enables the compiler option -mstack-guard and
 380           -mstack-size if they are available. If the compiler supports them
 381           it will emit additional code to each function prolog to trigger
 382           an illegal operation if the kernel stack is about to overflow.
 383
 384           Say N if you are unsure.
 385
 386 config STACK_GUARD
 387         int "Size of the guard area (128-1024)"
 388         range 128 1024
 389         depends on CHECK_STACK
 390         default "256"
 391         help
 392           This allows you to specify the size of the guard area at the lower
 393           end of the kernel stack. If the kernel stack points into the guard
 394           area on function entry an illegal operation is triggered. The size
 395           needs to be a power of 2. Please keep in mind that the size of an
 396           interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
 397           The minimum size for the stack guard should be 256 for 31 bit and
 398           512 for 64 bit.
 399
 400 config WARN_DYNAMIC_STACK
 401         def_bool n
 402         prompt "Emit compiler warnings for function with dynamic stack usage"
 403         help
 404           This option enables the compiler option -mwarn-dynamicstack. If the
 405           compiler supports this options generates warnings for functions
 406           that dynamically allocate stack space using alloca.
 407
 408           Say N if you are unsure.
 409
 410 endmenu
 411
 412 menu "I/O subsystem"
 413
 414 config QDIO
 415         def_tristate y
 416         prompt "QDIO support"
 417         ---help---
 418           This driver provides the Queued Direct I/O base support for
 419           IBM System z.
 420
 421           To compile this driver as a module, choose M here: the
 422           module will be called qdio.
 423
 424           If unsure, say Y.
 425
 426 config CHSC_SCH
 427         def_tristate m
 428         prompt "Support for CHSC subchannels"
 429         help
 430           This driver allows usage of CHSC subchannels. A CHSC subchannel
 431           is usually present on LPAR only.
 432           The driver creates a device /dev/chsc, which may be used to
 433           obtain I/O configuration information about the machine and
 434           to issue asynchronous chsc commands (DANGEROUS).
 435           You will usually only want to use this interface on a special
 436           LPAR designated for system management.
 437
 438           To compile this driver as a module, choose M here: the
 439           module will be called chsc_sch.
 440
 441           If unsure, say N.
 442
 443 config SCM_BUS
 444         def_bool y
 445         depends on 64BIT
 446         prompt "SCM bus driver"
 447         help
 448           Bus driver for Storage Class Memory.
 449
 450 config EADM_SCH
 451         def_tristate m
 452         prompt "Support for EADM subchannels"
 453         depends on SCM_BUS
 454         help
 455           This driver allows usage of EADM subchannels. EADM subchannels act
 456           as a communication vehicle for SCM increments.
 457
 458           To compile this driver as a module, choose M here: the
 459           module will be called eadm_sch.
 460
 461 endmenu
 462
 463 menu "Dump support"
 464
 465 config CRASH_DUMP
 466         bool "kernel crash dumps"
 467         depends on 64BIT && SMP
 468         select KEXEC
 469         help
 470           Generate crash dump after being started by kexec.
 471           Crash dump kernels are loaded in the main kernel with kexec-tools
 472           into a specially reserved region and then later executed after
 473           a crash by kdump/kexec.
 474           For more details see Documentation/kdump/kdump.txt
 475
 476 config ZFCPDUMP
 477         def_bool n
 478         prompt "zfcpdump support"
 479         select SMP
 480         help
 481           Select this option if you want to build an zfcpdump enabled kernel.
 482           Refer to <file:Documentation/s390/zfcpdump.txt> for more details on this.
 483
 484 endmenu
 485
 486 menu "Executable file formats / Emulations"
 487
 488 source "fs/Kconfig.binfmt"
 489
 490 config SECCOMP
 491         def_bool y
 492         prompt "Enable seccomp to safely compute untrusted bytecode"
 493         depends on PROC_FS
 494         help
 495           This kernel feature is useful for number crunching applications
 496           that may need to compute untrusted bytecode during their
 497           execution. By using pipes or other transports made available to
 498           the process as file descriptors supporting the read/write
 499           syscalls, it's possible to isolate those applications in
 500           their own address space using seccomp. Once seccomp is
 501           enabled via /proc/<pid>/seccomp, it cannot be disabled
 502           and the task is only allowed to execute a few safe syscalls
 503           defined by each seccomp mode.
 504
 505           If unsure, say Y.
 506
 507 endmenu
 508
 509 menu "Power Management"
 510
 511 config ARCH_HIBERNATION_POSSIBLE
 512         def_bool y if 64BIT
 513
 514 source "kernel/power/Kconfig"
 515
 516 endmenu
 517
 518 source "net/Kconfig"
 519
 520 config PCMCIA
 521         def_bool n
 522
 523 config CCW
 524         def_bool y
 525
 526 source "drivers/Kconfig"
 527
 528 source "fs/Kconfig"
 529
 530 source "arch/s390/Kconfig.debug"
 531
 532 source "security/Kconfig"
 533
 534 source "crypto/Kconfig"
 535
 536 source "lib/Kconfig"
 537
 538 menu "Virtualization"
 539
 540 config PFAULT
 541         def_bool y
 542         prompt "Pseudo page fault support"
 543         help
 544           Select this option, if you want to use PFAULT pseudo page fault
 545           handling under VM. If running native or in LPAR, this option
 546           has no effect. If your VM does not support PFAULT, PAGEEX
 547           pseudo page fault handling will be used.
 548           Note that VM 4.2 supports PFAULT but has a bug in its
 549           implementation that causes some problems.
 550           Everybody who wants to run Linux under VM != VM4.2 should select
 551           this option.
 552
 553 config SHARED_KERNEL
 554         bool "VM shared kernel support"
 555         depends on !JUMP_LABEL
 556         help
 557           Select this option, if you want to share the text segment of the
 558           Linux kernel between different VM guests. This reduces memory
 559           usage with lots of guests but greatly increases kernel size.
 560           Also if a kernel was IPL'ed from a shared segment the kexec system
 561           call will not work.
 562           You should only select this option if you know what you are
 563           doing and want to exploit this feature.
 564
 565 config CMM
 566         def_tristate n
 567         prompt "Cooperative memory management"
 568         help
 569           Select this option, if you want to enable the kernel interface
 570           to reduce the memory size of the system. This is accomplished
 571           by allocating pages of memory and put them "on hold". This only
 572           makes sense for a system running under VM where the unused pages
 573           will be reused by VM for other guest systems. The interface
 574           allows an external monitor to balance memory of many systems.
 575           Everybody who wants to run Linux under VM should select this
 576           option.
 577
 578 config CMM_IUCV
 579         def_bool y
 580         prompt "IUCV special message interface to cooperative memory management"
 581         depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
 582         help
 583           Select this option to enable the special message interface to
 584           the cooperative memory management.
 585
 586 config APPLDATA_BASE
 587         def_bool n
 588         prompt "Linux - VM Monitor Stream, base infrastructure"
 589         depends on PROC_FS
 590         help
 591           This provides a kernel interface for creating and updating z/VM APPLDATA
 592           monitor records. The monitor records are updated at certain time
 593           intervals, once the timer is started.
 594           Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
 595           i.e. enables or disables monitoring on the Linux side.
 596           A custom interval value (in seconds) can be written to
 597           /proc/appldata/interval.
 598
 599           Defaults are 60 seconds interval and timer off.
 600           The /proc entries can also be read from, showing the current settings.
 601
 602 config APPLDATA_MEM
 603         def_tristate m
 604         prompt "Monitor memory management statistics"
 605         depends on APPLDATA_BASE && VM_EVENT_COUNTERS
 606         help
 607           This provides memory management related data to the Linux - VM Monitor
 608           Stream, like paging/swapping rate, memory utilisation, etc.
 609           Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
 610           APPLDATA monitor record, i.e. enables or disables monitoring this record
 611           on the z/VM side.
 612
 613           Default is disabled.
 614           The /proc entry can also be read from, showing the current settings.
 615
 616           This can also be compiled as a module, which will be called
 617           appldata_mem.o.
 618
 619 config APPLDATA_OS
 620         def_tristate m
 621         prompt "Monitor OS statistics"
 622         depends on APPLDATA_BASE
 623         help
 624           This provides OS related data to the Linux - VM Monitor Stream, like
 625           CPU utilisation, etc.
 626           Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
 627           APPLDATA monitor record, i.e. enables or disables monitoring this record
 628           on the z/VM side.
 629
 630           Default is disabled.
 631           This can also be compiled as a module, which will be called
 632           appldata_os.o.
 633
 634 config APPLDATA_NET_SUM
 635         def_tristate m
 636         prompt "Monitor overall network statistics"
 637         depends on APPLDATA_BASE && NET
 638         help
 639           This provides network related data to the Linux - VM Monitor Stream,
 640           currently there is only a total sum of network I/O statistics, no
 641           per-interface data.
 642           Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
 643           APPLDATA monitor record, i.e. enables or disables monitoring this record
 644           on the z/VM side.
 645
 646           Default is disabled.
 647           This can also be compiled as a module, which will be called
 648           appldata_net_sum.o.
 649
 650 config S390_HYPFS_FS
 651         def_bool y
 652         prompt "s390 hypervisor file system support"
 653         select SYS_HYPERVISOR
 654         help
 655           This is a virtual file system intended to provide accounting
 656           information in an s390 hypervisor environment.
 657
 658 source "arch/s390/kvm/Kconfig"
 659
 660 config S390_GUEST
 661         def_bool y
 662         prompt "s390 support for virtio devices (EXPERIMENTAL)"
 663         depends on 64BIT && EXPERIMENTAL
 664         select VIRTUALIZATION
 665         select VIRTIO
 666         select VIRTIO_CONSOLE
 667         help
 668           Enabling this option adds support for virtio based paravirtual device
 669           drivers on s390.
 670
 671           Select this option if you want to run the kernel as a guest under
 672           the KVM hypervisor.
 673
 674 endmenu