The mhvtl tape library emulation package was originally based on the scsi_debug kernel driver, but has long since grown more complicated, with the mhvtl,ko kernel module now passing almost all SCSI commands to user-level daemons via a clunky device interface. It does this with an out-of-band driver, since the design is so bad it would never be accepted upstream.
And with the 4.20 kernel release, it has broken yet again, which is par for the course with out of band drivers.
I would like to get mhvtl working, and even better, replace the klunky kernel-user-space interface with netlink.
This project is one of its kind!