Table of Contents
The ccw bus typically contains the majority of devices available to a s390 system. Named after the channel command word (ccw), the basic command structure used to address its devices, the ccw bus contains so-called channel attached devices. They are addressed via I/O subchannels, visible on the css bus. A device driver for channel-attached devices, however, will never interact with the subchannel directly, but only via the I/O device on the ccw bus, the ccw device.
Some hardware structures have been translated into C structures for use by the common I/O layer and device drivers. For more information on the hardware structures represented here, please consult the Principles of Operation.