What you should know about the z/VM unit record device driver

7.1 z/VM guest

When the vmur module is loaded, it registers a character device with dynamic major number and a minor number region from 0x0 to 0xffff.

The minor number corresponds to the virtual device number of the virtual unit record device. A mechanism like udev is needed to automatically generate the respective device nodes. The default udev rules create the following device nodes:

  • Reader: /dev/vmrdr-0.0.<device_number>
  • Punch: /dev/vmpun-0.0.<device_number>
  • Printer: /dev/vmprt-0.0.<device_number>