As an endless subject, we need to modernize Xen hypervisor code for future (and current !) needs. This ranges from performance to security including software/hardware compatibility, ability to use modern CPU features, … We need to know agree on what to improve in Xen, and eventually how to plan to work on it (in a actionable way) and priorities, discuss on designs …
Some topics :
(note that some subjects are intertwined and inter-dependant)