Gerd Hoffmann 2017-05-24 06:20:36 EDT (In reply to Ademar Reis from ) >(In reply to Frediano Ziglio from ) >>Fixed by 0.17 version of the driver. >>If virtualization team want to allow migration to work even if resources are >>in Bar1 they should change Qemu code to allow that. >>Note that wddm dod is not officially supported by RHEL. Hmm, we can support that in qemu but requires a update to the live migration format, so it would come with quite some overhead for backward compatibility, such as requiring a new machine type.
Which implies backporting limitations (no z-stream). Also the guest driver can't just expect this to work as there will be old qemu versions not supporting this deployed for quite a while. Is there a compelling reason to place ressources in bar 1? Dell M4600 Mass Storage Controller Driver Windows 10.
Gerd Hoffmann 2017-05-24 07:11:17 EDT (In reply to Frediano Ziglio from ) >There are no reason like there are no reasons Qemu doing this limitation >beside implementation details. The reason why this limitation in qemu exists basically is 'historical reasons', dating back to the days where bar1 didn't exist.
Yes, from a design point of view it doesn't make sense. Likewise having the bar0 / bar1 split in the first place doesn't make sense. When re-designing qxl today with the lessons learned in the last years there a quite a few things I would do in a different way. But you have the memory in bar0, it makes sense to use it, so why not simply continue to place the commands there? You have to do that anyway to support older qemu versions. Either unconditionally (which would be the simplest and IMHO best way), or by detecting support and running different code paths in the driver depending on the qemu version you are running on. Which just increases your test matrix for no good reason.