This is to support booting from vfio-ccw dasd devices. We basically implement
the real hardware ipl procedure. This allows for booting Linux guests on
vfio-ccw devices.
vfio-ccw's channel program prefetch algorithm complicates ipl because most ipl
channel programs dynamically modify themselves. Details on the ipl process and
how we worked around this issue can be found in docs/devel/s390-dasd-ipl.txt.
This version brings better error handling, namely retrying I/O operations in the
event of some transient failure conditions. I've also renamed the sense data
structures and error output to indicate that they are for eckd dasd only. A few
other fixups as well, see changelog for details.