3D acceleration

I am still upgrading / downgrading components to try to figure out which one is failing.

Upgrade / downgrade game

Still going on this one. But after downgrading a few packages, and still seeing glxgears failing, I had to reboot the host (Firewall issue below) and hence the guest. And then glxgears started to work again. So this means a guest reboot is in order to validate the changes I do. Ugh.

After re-doing the filtering using the reboot procedure, I quickly zeroed on the problem being (unsuprisingly) mesa-dri-drivers. Tomorrow, will build from source and see if the problem is fixed on master.

Failing firewall

For some reason, I had to rearrange some network and power cables. I temporarily switched off my main physical switch. When it came back up, I was unable to connect to Muse with VNC.

The network was working OK. I could connect with ssh for example.

The VNC server was listening OK. I restarted it a couple of time, and checked that a telnet localhost 5900 on Muse worked. Similarly, netstat -tnlp | grep :5900 confirmed the port was alive locally. But a telnet muse 5900 from another machine was met with “connexion refused”. Running tcpdump -n host muse and port 5900 on Muse confirmed this was a firewall issue.

So I tried to reconfigure the firewall, change the port range to something smaller and back, restart the firewall, etc. Nothing would let the messages in. After half an hour of frustrating attempts, and since I had some other things to do after all, I restarted the machine, and I could VNC back in again.

I wonder what can trip the firewall like this.

Multi-monitor guest

I did some experiment with multi-monitor guests using Spice. Some things to remember:

  • It’s possible to connect directly to a guest with virt-viewer guest. Much easier than typing for example remote-viewer spice://localhost:5901.
  • If you still want to use remote-viewer, the domain display can be obtained with virsh domdisplay guest. In my case, this would output spice:// for example. As far as I know, this feature is still very poorly documented on-line, but it is in virsh help.

For now, I was unable to configure a multi-head guest that actually worked as I wanted. I tried two approaches:

  • Setting heads='4' in virsh edit guest. In that case, I can activate secondary displays in remote-viewer, but for some reason, all of my remote-viewer windows then switch to that secondary display, instead of staying on the first one.
  • Adding multiple QXL video devices. It looks like there is a somewhat shaky communication between xrandr and the QXL driver in that setup, the Gnome session dies and won’t let me log back in. xrandr did see multiple devices, though.

Updating Muse to latest Linux

Some of the virtual GPU code is only in the latest Linux kernel, 4.10, so I tried to update Muse to Linus Torvalds master, 37c85961c3f87f2141c84e53df31e59db072fd2e. That failed to boot for me. I did not spend too much time investigating, reverted to the Fedora 25 current kernel.



Author: Christophe de Dinechin

I try to change the world, but that's work in progress. If you want to know me, google "Christophe de Dinechin". Keywords: concept programming, virtualization, OS design, programming languages, video games, 3D, modern physics. Some stuff I did that I'm proud of: the first "true" 3D game for the PC, HP's big iron virtualization, real-time test systems for car electronics, some of the best games for the HP48 calculator, a theory of physics that makes sense (at least to me).

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