xref: /linux-4.1.27/arch/s390/Kconfig

config MMU
	def_bool y

config ZONE_DMA
	def_bool y

config LOCKDEP_SUPPORT
	def_bool y

config STACKTRACE_SUPPORT
	def_bool y

config HAVE_LATENCYTOP_SUPPORT
	def_bool y

config RWSEM_GENERIC_SPINLOCK
	bool

config RWSEM_XCHGADD_ALGORITHM
	def_bool y

config ARCH_HAS_ILOG2_U32
	def_bool n

config ARCH_HAS_ILOG2_U64
	def_bool n

config GENERIC_HWEIGHT
	def_bool y

config GENERIC_BUG
	def_bool y if BUG

config GENERIC_BUG_RELATIVE_POINTERS
	def_bool y

config ARCH_DMA_ADDR_T_64BIT
	def_bool y

config GENERIC_LOCKBREAK
	def_bool y if SMP && PREEMPT

config PGSTE
	def_bool y if KVM

config ARCH_SUPPORTS_DEBUG_PAGEALLOC
	def_bool y

config KEXEC
	def_bool y

config AUDIT_ARCH
	def_bool y

config NO_IOPORT_MAP
	def_bool y

config PCI_QUIRKS
	def_bool n

config ARCH_SUPPORTS_UPROBES
	def_bool y

config S390
	def_bool y
	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
	select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
	select ARCH_HAS_ELF_RANDOMIZE
	select ARCH_HAS_GCOV_PROFILE_ALL
	select ARCH_HAS_SG_CHAIN
	select ARCH_HAVE_NMI_SAFE_CMPXCHG
	select ARCH_INLINE_READ_LOCK
	select ARCH_INLINE_READ_LOCK_BH
	select ARCH_INLINE_READ_LOCK_IRQ
	select ARCH_INLINE_READ_LOCK_IRQSAVE
	select ARCH_INLINE_READ_TRYLOCK
	select ARCH_INLINE_READ_UNLOCK
	select ARCH_INLINE_READ_UNLOCK_BH
	select ARCH_INLINE_READ_UNLOCK_IRQ
	select ARCH_INLINE_READ_UNLOCK_IRQRESTORE
	select ARCH_INLINE_SPIN_LOCK
	select ARCH_INLINE_SPIN_LOCK_BH
	select ARCH_INLINE_SPIN_LOCK_IRQ
	select ARCH_INLINE_SPIN_LOCK_IRQSAVE
	select ARCH_INLINE_SPIN_TRYLOCK
	select ARCH_INLINE_SPIN_TRYLOCK_BH
	select ARCH_INLINE_SPIN_UNLOCK
	select ARCH_INLINE_SPIN_UNLOCK_BH
	select ARCH_INLINE_SPIN_UNLOCK_IRQ
	select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE
	select ARCH_INLINE_WRITE_LOCK
	select ARCH_INLINE_WRITE_LOCK_BH
	select ARCH_INLINE_WRITE_LOCK_IRQ
	select ARCH_INLINE_WRITE_LOCK_IRQSAVE
	select ARCH_INLINE_WRITE_TRYLOCK
	select ARCH_INLINE_WRITE_UNLOCK
	select ARCH_INLINE_WRITE_UNLOCK_BH
	select ARCH_INLINE_WRITE_UNLOCK_IRQ
	select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
	select ARCH_SAVE_PAGE_KEYS if HIBERNATION
	select ARCH_SUPPORTS_ATOMIC_RMW
	select ARCH_USE_CMPXCHG_LOCKREF
	select ARCH_WANT_IPC_PARSE_VERSION
	select BUILDTIME_EXTABLE_SORT
	select CLONE_BACKWARDS2
	select DYNAMIC_FTRACE if FUNCTION_TRACER
	select GENERIC_CLOCKEVENTS
	select GENERIC_CPU_DEVICES if !SMP
	select GENERIC_FIND_FIRST_BIT
	select GENERIC_SMP_IDLE_THREAD
	select GENERIC_TIME_VSYSCALL
	select HAVE_ALIGNED_STRUCT_PAGE if SLUB
	select HAVE_ARCH_AUDITSYSCALL
	select HAVE_ARCH_JUMP_LABEL
	select HAVE_ARCH_SECCOMP_FILTER
	select HAVE_ARCH_TRACEHOOK
	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
	select HAVE_BPF_JIT if PACK_STACK && HAVE_MARCH_Z196_FEATURES
	select HAVE_CMPXCHG_DOUBLE
	select HAVE_CMPXCHG_LOCAL
	select HAVE_DEBUG_KMEMLEAK
	select HAVE_DYNAMIC_FTRACE
	select HAVE_DYNAMIC_FTRACE_WITH_REGS
	select HAVE_FTRACE_MCOUNT_RECORD
	select HAVE_FUNCTION_GRAPH_TRACER
	select HAVE_FUNCTION_TRACER
	select HAVE_FUTEX_CMPXCHG if FUTEX
	select HAVE_KERNEL_BZIP2
	select HAVE_KERNEL_GZIP
	select HAVE_KERNEL_LZ4
	select HAVE_KERNEL_LZMA
	select HAVE_KERNEL_LZO
	select HAVE_KERNEL_XZ
	select HAVE_KPROBES
	select HAVE_KRETPROBES
	select HAVE_KVM
	select HAVE_LIVEPATCH
	select HAVE_MEMBLOCK
	select HAVE_MEMBLOCK_NODE_MAP
	select HAVE_MEMBLOCK_PHYS_MAP
	select HAVE_MOD_ARCH_SPECIFIC
	select HAVE_OPROFILE
	select HAVE_PERF_EVENTS
	select HAVE_REGS_AND_STACK_ACCESS_API
	select HAVE_SYSCALL_TRACEPOINTS
	select HAVE_VIRT_CPU_ACCOUNTING
	select MODULES_USE_ELF_RELA
	select NO_BOOTMEM
	select OLD_SIGACTION
	select OLD_SIGSUSPEND3
	select SYSCTL_EXCEPTION_TRACE
	select TTY
	select VIRT_CPU_ACCOUNTING
	select VIRT_TO_BUS

config SCHED_OMIT_FRAME_POINTER
	def_bool y

config PGTABLE_LEVELS
	int
	default 4 if 64BIT
	default 2

source "init/Kconfig"

source "kernel/Kconfig.freezer"

source "kernel/livepatch/Kconfig"

menu "Processor type and features"

config HAVE_MARCH_Z900_FEATURES
	def_bool n

config HAVE_MARCH_Z990_FEATURES
	def_bool n
	select HAVE_MARCH_Z900_FEATURES

config HAVE_MARCH_Z9_109_FEATURES
	def_bool n
	select HAVE_MARCH_Z990_FEATURES

config HAVE_MARCH_Z10_FEATURES
	def_bool n
	select HAVE_MARCH_Z9_109_FEATURES

config HAVE_MARCH_Z196_FEATURES
	def_bool n
	select HAVE_MARCH_Z10_FEATURES

config HAVE_MARCH_ZEC12_FEATURES
	def_bool n
	select HAVE_MARCH_Z196_FEATURES

config HAVE_MARCH_Z13_FEATURES
	def_bool n
	select HAVE_MARCH_ZEC12_FEATURES

choice
	prompt "Processor type"
	default MARCH_Z900

config MARCH_Z900
	bool "IBM zSeries model z800 and z900"
	select HAVE_MARCH_Z900_FEATURES
	help
	  Select this to enable optimizations for model z800/z900 (2064 and
	  2066 series). This will enable some optimizations that are not
	  available on older ESA/390 (31 Bit) only CPUs.

config MARCH_Z990
	bool "IBM zSeries model z890 and z990"
	select HAVE_MARCH_Z990_FEATURES
	help
	  Select this to enable optimizations for model z890/z990 (2084 and
	  2086 series). The kernel will be slightly faster but will not work
	  on older machines.

config MARCH_Z9_109
	bool "IBM System z9"
	select HAVE_MARCH_Z9_109_FEATURES
	help
	  Select this to enable optimizations for IBM System z9 (2094 and
	  2096 series). The kernel will be slightly faster but will not work
	  on older machines.

config MARCH_Z10
	bool "IBM System z10"
	select HAVE_MARCH_Z10_FEATURES
	help
	  Select this to enable optimizations for IBM System z10 (2097 and
	  2098 series). The kernel will be slightly faster but will not work
	  on older machines.

config MARCH_Z196
	bool "IBM zEnterprise 114 and 196"
	select HAVE_MARCH_Z196_FEATURES
	help
	  Select this to enable optimizations for IBM zEnterprise 114 and 196
	  (2818 and 2817 series). The kernel will be slightly faster but will
	  not work on older machines.

config MARCH_ZEC12
	bool "IBM zBC12 and zEC12"
	select HAVE_MARCH_ZEC12_FEATURES
	help
	  Select this to enable optimizations for IBM zBC12 and zEC12 (2828 and
	  2827 series). The kernel will be slightly faster but will not work on
	  older machines.

config MARCH_Z13
	bool "IBM z13"
	select HAVE_MARCH_Z13_FEATURES
	help
	  Select this to enable optimizations for IBM z13 (2964 series).
	  The kernel will be slightly faster but will not work on older
	  machines.

endchoice

config MARCH_Z900_TUNE
	def_bool TUNE_Z900 || MARCH_Z900 && TUNE_DEFAULT

config MARCH_Z990_TUNE
	def_bool TUNE_Z990 || MARCH_Z990 && TUNE_DEFAULT

config MARCH_Z9_109_TUNE
	def_bool TUNE_Z9_109 || MARCH_Z9_109 && TUNE_DEFAULT

config MARCH_Z10_TUNE
	def_bool TUNE_Z10 || MARCH_Z10 && TUNE_DEFAULT

config MARCH_Z196_TUNE
	def_bool TUNE_Z196 || MARCH_Z196 && TUNE_DEFAULT

config MARCH_ZEC12_TUNE
	def_bool TUNE_ZEC12 || MARCH_ZEC12 && TUNE_DEFAULT

config MARCH_Z13_TUNE
	def_bool TUNE_Z13 || MARCH_Z13 && TUNE_DEFAULT

choice
	prompt "Tune code generation"
	default TUNE_DEFAULT
	help
	  Cause the compiler to tune (-mtune) the generated code for a machine.
	  This will make the code run faster on the selected machine but
	  somewhat slower on other machines.
	  This option only changes how the compiler emits instructions, not the
	  selection of instructions itself, so the resulting kernel will run on
	  all other machines.

config TUNE_DEFAULT
	bool "Default"
	help
	  Tune the generated code for the target processor for which the kernel
	  will be compiled.

config TUNE_Z900
	bool "IBM zSeries model z800 and z900"

config TUNE_Z990
	bool "IBM zSeries model z890 and z990"

config TUNE_Z9_109
	bool "IBM System z9"

config TUNE_Z10
	bool "IBM System z10"

config TUNE_Z196
	bool "IBM zEnterprise 114 and 196"

config TUNE_ZEC12
	bool "IBM zBC12 and zEC12"

config TUNE_Z13
	bool "IBM z13"

endchoice

config 64BIT
	def_bool y

config COMPAT
	def_bool y
	prompt "Kernel support for 31 bit emulation"
	select COMPAT_BINFMT_ELF if BINFMT_ELF
	select ARCH_WANT_OLD_COMPAT_IPC
	select COMPAT_OLD_SIGACTION
	depends on MULTIUSER
	help
	  Select this option if you want to enable your system kernel to
	  handle system-calls from ELF binaries for 31 bit ESA.  This option
	  (and some other stuff like libraries and such) is needed for
	  executing 31 bit applications.  It is safe to say "Y".

config SYSVIPC_COMPAT
	def_bool y if COMPAT && SYSVIPC

config KEYS_COMPAT
	def_bool y if COMPAT && KEYS

config SMP
	def_bool y
	prompt "Symmetric multi-processing support"
	---help---
	  This enables support for systems with more than one CPU. If you have
	  a system with only one CPU, like most personal computers, say N. If
	  you have a system with more than one CPU, say Y.

	  If you say N here, the kernel will run on uni- and multiprocessor
	  machines, but will use only one CPU of a multiprocessor machine. If
	  you say Y here, the kernel will run on many, but not all,
	  uniprocessor machines. On a uniprocessor machine, the kernel
	  will run faster if you say N here.

	  See also the SMP-HOWTO available at
	  <http://www.tldp.org/docs.html#howto>.

	  Even if you don't know what to do here, say Y.

config NR_CPUS
	int "Maximum number of CPUs (2-512)"
	range 2 512
	depends on SMP
	default "64"
	help
	  This allows you to specify the maximum number of CPUs which this
	  kernel will support. The maximum supported value is 512 and the
	  minimum value which makes sense is 2.

	  This is purely to save memory - each supported CPU adds
	  approximately sixteen kilobytes to the kernel image.

config HOTPLUG_CPU
	def_bool y
	prompt "Support for hot-pluggable CPUs"
	depends on SMP
	help
	  Say Y here to be able to turn CPUs off and on. CPUs
	  can be controlled through /sys/devices/system/cpu/cpu#.
	  Say N if you want to disable CPU hotplug.

config SCHED_SMT
	def_bool n

config SCHED_MC
	def_bool n

config SCHED_BOOK
	def_bool n

config SCHED_TOPOLOGY
	def_bool y
	prompt "Topology scheduler support"
	depends on SMP
	select SCHED_SMT
	select SCHED_MC
	select SCHED_BOOK
	help
	  Topology scheduler support improves the CPU scheduler's decision
	  making when dealing with machines that have multi-threading,
	  multiple cores or multiple books.

source kernel/Kconfig.preempt

source kernel/Kconfig.hz

endmenu

menu "Memory setup"

config ARCH_SPARSEMEM_ENABLE
	def_bool y
	select SPARSEMEM_VMEMMAP_ENABLE
	select SPARSEMEM_VMEMMAP

config ARCH_SPARSEMEM_DEFAULT
	def_bool y

config ARCH_SELECT_MEMORY_MODEL
	def_bool y

config ARCH_ENABLE_MEMORY_HOTPLUG
	def_bool y if SPARSEMEM

config ARCH_ENABLE_MEMORY_HOTREMOVE
	def_bool y

config ARCH_ENABLE_SPLIT_PMD_PTLOCK
	def_bool y

config FORCE_MAX_ZONEORDER
	int
	default "9"

source "mm/Kconfig"

config PACK_STACK
	def_bool y
	prompt "Pack kernel stack"
	help
	  This option enables the compiler option -mkernel-backchain if it
	  is available. If the option is available the compiler supports
	  the new stack layout which dramatically reduces the minimum stack
	  frame size. With an old compiler a non-leaf function needs a
	  minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
	  -mkernel-backchain the minimum size drops to 16 byte on 31 bit
	  and 24 byte on 64 bit.

	  Say Y if you are unsure.

config CHECK_STACK
	def_bool y
	prompt "Detect kernel stack overflow"
	help
	  This option enables the compiler option -mstack-guard and
	  -mstack-size if they are available. If the compiler supports them
	  it will emit additional code to each function prolog to trigger
	  an illegal operation if the kernel stack is about to overflow.

	  Say N if you are unsure.

config STACK_GUARD
	int "Size of the guard area (128-1024)"
	range 128 1024
	depends on CHECK_STACK
	default "256"
	help
	  This allows you to specify the size of the guard area at the lower
	  end of the kernel stack. If the kernel stack points into the guard
	  area on function entry an illegal operation is triggered. The size
	  needs to be a power of 2. Please keep in mind that the size of an
	  interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
	  The minimum size for the stack guard should be 256 for 31 bit and
	  512 for 64 bit.

config WARN_DYNAMIC_STACK
	def_bool n
	prompt "Emit compiler warnings for function with dynamic stack usage"
	help
	  This option enables the compiler option -mwarn-dynamicstack. If the
	  compiler supports this options generates warnings for functions
	  that dynamically allocate stack space using alloca.

	  Say N if you are unsure.

endmenu

menu "I/O subsystem"

config QDIO
	def_tristate y
	prompt "QDIO support"
	---help---
	  This driver provides the Queued Direct I/O base support for
	  IBM System z.

	  To compile this driver as a module, choose M here: the
	  module will be called qdio.

	  If unsure, say Y.

menuconfig PCI
	bool "PCI support"
	select HAVE_DMA_ATTRS
	select PCI_MSI
	help
	  Enable PCI support.

if PCI

config PCI_NR_FUNCTIONS
	int "Maximum number of PCI functions (1-4096)"
	range 1 4096
	default "64"
	help
	  This allows you to specify the maximum number of PCI functions which
	  this kernel will support.

config PCI_NR_MSI
	int "Maximum number of MSI interrupts (64-32768)"
	range 64 32768
	default "256"
	help
	  This defines the number of virtual interrupts the kernel will
	  provide for MSI interrupts. If you configure your system to have
	  too few drivers will fail to allocate MSI interrupts for all
	  PCI devices.

source "drivers/pci/Kconfig"
source "drivers/pci/pcie/Kconfig"
source "drivers/pci/hotplug/Kconfig"

endif	# PCI

config PCI_DOMAINS
	def_bool PCI

config HAS_IOMEM
	def_bool PCI

config IOMMU_HELPER
	def_bool PCI

config HAS_DMA
	def_bool PCI
	select HAVE_DMA_API_DEBUG

config NEED_SG_DMA_LENGTH
	def_bool PCI

config NEED_DMA_MAP_STATE
	def_bool PCI

config CHSC_SCH
	def_tristate m
	prompt "Support for CHSC subchannels"
	help
	  This driver allows usage of CHSC subchannels. A CHSC subchannel
	  is usually present on LPAR only.
	  The driver creates a device /dev/chsc, which may be used to
	  obtain I/O configuration information about the machine and
	  to issue asynchronous chsc commands (DANGEROUS).
	  You will usually only want to use this interface on a special
	  LPAR designated for system management.

	  To compile this driver as a module, choose M here: the
	  module will be called chsc_sch.

	  If unsure, say N.

config SCM_BUS
	def_bool y
	prompt "SCM bus driver"
	help
	  Bus driver for Storage Class Memory.

config EADM_SCH
	def_tristate m
	prompt "Support for EADM subchannels"
	depends on SCM_BUS
	help
	  This driver allows usage of EADM subchannels. EADM subchannels act
	  as a communication vehicle for SCM increments.

	  To compile this driver as a module, choose M here: the
	  module will be called eadm_sch.

endmenu

menu "Dump support"

config CRASH_DUMP
	bool "kernel crash dumps"
	depends on SMP
	select KEXEC
	help
	  Generate crash dump after being started by kexec.
	  Crash dump kernels are loaded in the main kernel with kexec-tools
	  into a specially reserved region and then later executed after
	  a crash by kdump/kexec.
	  Refer to <file:Documentation/s390/zfcpdump.txt> for more details on this.
	  This option also enables s390 zfcpdump.
	  See also <file:Documentation/s390/zfcpdump.txt>

endmenu

menu "Executable file formats / Emulations"

source "fs/Kconfig.binfmt"

config SECCOMP
	def_bool y
	prompt "Enable seccomp to safely compute untrusted bytecode"
	depends on PROC_FS
	help
	  This kernel feature is useful for number crunching applications
	  that may need to compute untrusted bytecode during their
	  execution. By using pipes or other transports made available to
	  the process as file descriptors supporting the read/write
	  syscalls, it's possible to isolate those applications in
	  their own address space using seccomp. Once seccomp is
	  enabled via /proc/<pid>/seccomp, it cannot be disabled
	  and the task is only allowed to execute a few safe syscalls
	  defined by each seccomp mode.

	  If unsure, say Y.

endmenu

menu "Power Management"

config ARCH_HIBERNATION_POSSIBLE
	def_bool y

source "kernel/power/Kconfig"

endmenu

source "net/Kconfig"

config PCMCIA
	def_bool n

config CCW
	def_bool y

source "drivers/Kconfig"

source "fs/Kconfig"

source "arch/s390/Kconfig.debug"

source "security/Kconfig"

source "crypto/Kconfig"

source "lib/Kconfig"

menu "Virtualization"

config PFAULT
	def_bool y
	prompt "Pseudo page fault support"
	help
	  Select this option, if you want to use PFAULT pseudo page fault
	  handling under VM. If running native or in LPAR, this option
	  has no effect. If your VM does not support PFAULT, PAGEEX
	  pseudo page fault handling will be used.
	  Note that VM 4.2 supports PFAULT but has a bug in its
	  implementation that causes some problems.
	  Everybody who wants to run Linux under VM != VM4.2 should select
	  this option.

config SHARED_KERNEL
	bool "VM shared kernel support"
	depends on !JUMP_LABEL
	help
	  Select this option, if you want to share the text segment of the
	  Linux kernel between different VM guests. This reduces memory
	  usage with lots of guests but greatly increases kernel size.
	  Also if a kernel was IPL'ed from a shared segment the kexec system
	  call will not work.
	  You should only select this option if you know what you are
	  doing and want to exploit this feature.

config CMM
	def_tristate n
	prompt "Cooperative memory management"
	help
	  Select this option, if you want to enable the kernel interface
	  to reduce the memory size of the system. This is accomplished
	  by allocating pages of memory and put them "on hold". This only
	  makes sense for a system running under VM where the unused pages
	  will be reused by VM for other guest systems. The interface
	  allows an external monitor to balance memory of many systems.
	  Everybody who wants to run Linux under VM should select this
	  option.

config CMM_IUCV
	def_bool y
	prompt "IUCV special message interface to cooperative memory management"
	depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
	help
	  Select this option to enable the special message interface to
	  the cooperative memory management.

config APPLDATA_BASE
	def_bool n
	prompt "Linux - VM Monitor Stream, base infrastructure"
	depends on PROC_FS
	help
	  This provides a kernel interface for creating and updating z/VM APPLDATA
	  monitor records. The monitor records are updated at certain time
	  intervals, once the timer is started.
	  Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
	  i.e. enables or disables monitoring on the Linux side.
	  A custom interval value (in seconds) can be written to
	  /proc/appldata/interval.

	  Defaults are 60 seconds interval and timer off.
	  The /proc entries can also be read from, showing the current settings.

config APPLDATA_MEM
	def_tristate m
	prompt "Monitor memory management statistics"
	depends on APPLDATA_BASE && VM_EVENT_COUNTERS
	help
	  This provides memory management related data to the Linux - VM Monitor
	  Stream, like paging/swapping rate, memory utilisation, etc.
	  Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
	  APPLDATA monitor record, i.e. enables or disables monitoring this record
	  on the z/VM side.

	  Default is disabled.
	  The /proc entry can also be read from, showing the current settings.

	  This can also be compiled as a module, which will be called
	  appldata_mem.o.

config APPLDATA_OS
	def_tristate m
	prompt "Monitor OS statistics"
	depends on APPLDATA_BASE
	help
	  This provides OS related data to the Linux - VM Monitor Stream, like
	  CPU utilisation, etc.
	  Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
	  APPLDATA monitor record, i.e. enables or disables monitoring this record
	  on the z/VM side.

	  Default is disabled.
	  This can also be compiled as a module, which will be called
	  appldata_os.o.

config APPLDATA_NET_SUM
	def_tristate m
	prompt "Monitor overall network statistics"
	depends on APPLDATA_BASE && NET
	help
	  This provides network related data to the Linux - VM Monitor Stream,
	  currently there is only a total sum of network I/O statistics, no
	  per-interface data.
	  Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
	  APPLDATA monitor record, i.e. enables or disables monitoring this record
	  on the z/VM side.

	  Default is disabled.
	  This can also be compiled as a module, which will be called
	  appldata_net_sum.o.

config S390_HYPFS_FS
	def_bool y
	prompt "s390 hypervisor file system support"
	select SYS_HYPERVISOR
	help
	  This is a virtual file system intended to provide accounting
	  information in an s390 hypervisor environment.

source "arch/s390/kvm/Kconfig"

config S390_GUEST
	def_bool y
	prompt "s390 support for virtio devices"
	select TTY
	select VIRTUALIZATION
	select VIRTIO
	select VIRTIO_CONSOLE
	help
	  Enabling this option adds support for virtio based paravirtual device
	  drivers on s390.

	  Select this option if you want to run the kernel as a guest under
	  the KVM hypervisor.

endmenu