[libvirt] Opinions on removing the old, legacy libvirt Xen driver

[Jim Fehlig]

Hi All,

I briefly mentioned this at an evening event during the KVM Forum / Xen Dev 
Summit, but the list is certainly a better place to discuss such a topic. What 
do folks think about finally removing the old, legacy, xend-based driver from 
the libvirt sources?

The Xen community made xl/libxl the primary toolstack in Xen 4.1. In Xen 4.2, it 
was made the default toolstack. In Xen 4.5, xm/xend was completely removed from 
the Xen source tree. According to the Xen release support matrix [0], upstream 
maintenance of Xen 4.1-4.3 has been dropped for some time, including "long term" 
security support. Xen 4.4-4.5 no longer receive regular maintenance support, 
with security support ending in March for 4.4 and January 2018 for 4.5. In 
short, the fully maintained upstream Xen releases don't even contain xm/xend :-).

As for downstreams, I doubt anyone is interested in running the last several 
libvirt releases on an old Xen installition with xm/xend, let alone libvirt.git 
master. SUSE, which still supports Xen, has no interest in using a new libvirt 
on older (but still supported) SLES that uses the xm/xend toolstack. I struggle 
to find a good reason to keep any of the old cruft under src/xen/. I do think we 
should keep the xm/sexpr config parsing/formatting code src/xenconfig/ since it 
is useful for converting old xm and sexpr config to libvirt domXML.

Thanks for opinions and comments!

Regards,
Jim

[0] https://wiki.xenproject.org/wiki/Xen_Project_Release_Features