GIF89a;
Direktori : /lib/modules/3.10.0-957.21.3.el7.centos.plus.x86_64/source/arch/s390/ |
Current File : //lib/modules/3.10.0-957.21.3.el7.centos.plus.x86_64/source/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 64BIT 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 select KEXEC_CORE config AUDIT_ARCH def_bool y config NO_IOPORT def_bool y config PCI_QUIRKS def_bool n config ARCH_SUPPORTS_UPROBES def_bool 64BIT config S390 def_bool y select ARCH_DISCARD_MEMBLOCK select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE select ARCH_HAS_ELF_RANDOMIZE 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_HAS_DEBUG_STRICT_USER_COPY_CHECKS select ARCH_SAVE_PAGE_KEYS if HIBERNATION select ARCH_USE_CMPXCHG_LOCKREF select ARCH_WANT_IPC_PARSE_VERSION select ARCH_USES_HIGH_VMA_FLAGS if 64BIT select BUILDTIME_EXTABLE_SORT select CLONE_BACKWARDS2 select DYNAMIC_FTRACE if FUNCTION_TRACER select GENERIC_CLOCKEVENTS select GENERIC_CPU_DEVICES if !SMP select GENERIC_CPU_VULNERABILITIES select GENERIC_SMP_IDLE_THREAD select GENERIC_TIME_VSYSCALL select HAVE_ALIGNED_STRUCT_PAGE if SLUB select HAVE_ARCH_JUMP_LABEL if !MARCH_G5 select HAVE_ARCH_SECCOMP_FILTER select HAVE_ARCH_TRACEHOOK select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT select HAVE_EBPF_JIT if 64BIT && PACK_STACK select HAVE_CMPXCHG_DOUBLE select HAVE_CMPXCHG_LOCAL select HAVE_C_RECORDMCOUNT select HAVE_DEBUG_KMEMLEAK select HAVE_DMA_API_DEBUG select HAVE_DYNAMIC_FTRACE select HAVE_DYNAMIC_FTRACE_WITH_REGS if 64BIT select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_TRACER select HAVE_KERNEL_BZIP2 select HAVE_KERNEL_GZIP select HAVE_KERNEL_LZMA select HAVE_KERNEL_LZO select HAVE_KERNEL_XZ select HAVE_KPROBES select HAVE_KRETPROBES select HAVE_KVM if 64BIT select HAVE_LIVEPATCH select HAVE_MEMBLOCK select HAVE_MEMBLOCK_NODE_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_UID16 if 32BIT select HAVE_VIRT_CPU_ACCOUNTING select VIRT_TO_BUS select KTIME_SCALAR if 32BIT select MODULES_USE_ELF_RELA select OLD_SIGSUSPEND3 select OLD_SIGACTION select SYSCTL_EXCEPTION_TRACE select USE_GENERIC_SMP_HELPERS if SMP select VIRT_CPU_ACCOUNTING config SCHED_OMIT_FRAME_POINTER def_bool y 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_G5 config MARCH_G5 bool "System/390 model G5 and G6" depends on !64BIT help Select this to build a 31 bit kernel that works on all ESA/390 and z/Architecture machines. config MARCH_Z900 bool "IBM zSeries model z800 and z900" select HAVE_MARCH_Z900_FEATURES if 64BIT 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 if 64BIT 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 if 64BIT 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 if 64BIT 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 if 64BIT 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 if 64BIT 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 if 64BIT 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_G5_TUNE def_bool TUNE_G5 || MARCH_G5 && TUNE_DEFAULT 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_G5 bool "System/390 model G5 and G6" 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 prompt "64 bit kernel" help Select this option if you have an IBM z/Architecture machine and want to use the 64 bit addressing mode. config 32BIT def_bool y if !64BIT config COMPAT def_bool y prompt "Kernel support for 31 bit emulation" depends on 64BIT select COMPAT_BINFMT_ELF if BINFMT_ELF select ARCH_WANT_OLD_COMPAT_IPC select COMPAT_OLD_SIGACTION 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 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 single 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, singleprocessor machines. On a singleprocessor 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 (2-256)" range 2 256 depends on SMP default "32" if !64BIT default "64" if 64BIT help This allows you to specify the maximum number of CPUs which this kernel will support. The maximum supported value is 256 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_DRAWER 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 select SCHED_DRAWER 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 config MATHEMU def_bool y prompt "IEEE FPU emulation" depends on MARCH_G5 help This option is required for IEEE compliant floating point arithmetic on older ESA/390 machines. Say Y unless you know your machine doesn't need this. source kernel/Kconfig.hz config ARCH_RANDOM def_bool y prompt "s390 architectural random number generation API" help Enable the s390 architectural random number generation API to provide random data for all consumers within the Linux kernel. When enabled the arch_random_* functions declared in linux/random.h are implemented. The implementation is based on the s390 CPACF instruction subfunction TRNG which provides a real true random number generator. If unsure, say Y. config KERNEL_NOBP def_bool n prompt "Enable modified branch prediction for the kernel by default" help If this option is selected the kernel will switch to a modified branch prediction mode if the firmware interface is available. The modified branch prediction mode improves the behaviour in regard to speculative execution. With the option enabled the kernel parameter "nobp=0" or "nospec" can be used to run the kernel in the normal branch prediction mode. With the option disabled the modified branch prediction mode is enabled with the "nobp=1" kernel parameter. If unsure, say N. config EXPOLINE def_bool n prompt "Avoid speculative indirect branches in the kernel" depends on 64BIT help Compile the kernel with the expoline compiler options to guard against kernel-to-user data leaks by avoiding speculative indirect branches. Requires a compiler with -mindirect-branch=thunk support for full protection. The kernel may run slower. If unsure, say N. choice prompt "Expoline default" depends on EXPOLINE default EXPOLINE_FULL config EXPOLINE_OFF bool "spectre_v2=off" config EXPOLINE_AUTO bool "spectre_v2=auto" config EXPOLINE_FULL bool "spectre_v2=on" endchoice endmenu menu "Memory setup" config ARCH_SPARSEMEM_ENABLE def_bool y select SPARSEMEM_VMEMMAP_ENABLE select SPARSEMEM_VMEMMAP select SPARSEMEM_STATIC if !64BIT 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_HAS_ADD_PAGES def_bool y depends on ARCH_ENABLE_MEMORY_HOTPLUG 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" depends on 64BIT 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. source "drivers/pci/Kconfig" endif # PCI config PCI_DOMAINS def_bool PCI config HAS_IOMEM def_bool PCI config IOMMU_HELPER def_bool PCI 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 depends on 64BIT 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 KEXEC_AUTO_RESERVE bool "automatically reserve memory for kexec kernel" depends on KEXEC default y ---help--- Automatically reserve memory for a kexec kernel, so that you don't need to specify numbers for the "crashkernel=X@Y" boot option, instead you can use "crashkernel=auto". This option works for systems that have at least 4 GiB memory. Then 128 MiB plus a small amount of additional memory that grows linearly with the 1st kernel memory size is reserved. When "crashkernel=auto" is used for systems with less than 4 GiB memory, no crashkernel memory will be reserved. config CRASH_DUMP bool "kernel crash dumps" depends on 64BIT && SMP select KEXEC select ZFCPDUMP 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. For more details see Documentation/kdump/kdump.txt config ZFCPDUMP def_bool n prompt "zfcpdump support" depends on SMP help Select this option if you want to build an zfcpdump enabled kernel. Refer to <file:Documentation/s390/zfcpdump.txt> for more details on this. 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 if 64BIT 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" depends on 64BIT 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. config S390_GUEST_OLD_TRANSPORT def_bool y prompt "Guest support for old s390 virtio transport (DEPRECATED)" depends on S390_GUEST help Enable this option to add support for the old s390-virtio transport (i.e. virtio devices NOT based on virtio-ccw). This type of virtio devices is only available on the experimental kuli userspace or with old (< 2.6) qemu. If you are running with a modern version of qemu (which supports virtio-ccw since 1.4 and uses it by default since version 2.4), you probably won't need this. endmenu