[adding libvirt] On 05/09/2014 05:54 AM, Gerd Hoffmann wrote:
Hi,
virt-manager/libvirt seems to default to 9 MByte of Vram for cirrus, so this would break a lot of setups.
It wouldn't. libvirt sticks that into the xml, but it doesn't set any qemu parameters. The libvirt parameter actually predates the qemu property for setting the size.
Then we should probably re-evaluate what libvirt does with the parameters, which avoids breaking any guest that happens to be pre-existing with the odd 9MB sizing in the XML.
Looking at datasheets on the web seems to say the chips actually went down to 1 MB or less.
I have my doubts we emulate that correctly (register telling the guest how much memory is actually there etc.). Also it is pretty much useless these days, even the 4MB imply serious constrains when FullHD displays are commonplace. Newer cirrus drivers such as the kernel's drm driver are specifically written to qemu's cirrus cards, I have my doubs that they are prepared to handle 1MB cirrus cards correctly.
Bottom line: Allowing less than 4MB is asking for trouble for no good reason ;)
cheers, Gerd
-- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org