On Sat, May 22, 2021 at 9:09 PM gansteed <gansteed@gmail.com> wrote:

Hello:
I'm using kvm to host a windows 7 guest vm, I've install the latest spice guest tools from https://spice-space.org/download/windows/spice-guest-tools/spice-guest-tools-latest.exe, and I've set video section like this:

<video>
<model type="qxl" ram="262144" vram="262144" vram64="262144" vgamem="131072" heads="1" primary="yes"/>
<alias name="video0"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x01" function="0x0"/>
</video>

but the graphics in windows guest is laggy, I' found that the guest have only use 16MB as vram:

How can I increase the real usage of vram in the windows guest vm?

There is no libvirt API or QEMU qmp to update video devices when a VM is live.

You should shut off the VM and then edit the VM xml to update the values of ram or vram in the qxl video element.

For the meaning of ram or vram, see https://libvirt.org/formatdomain.html#video-devices