I have a Radeon HD 4350.
I have KMS and 3D working, but there are still some issues and don't know if they are bugs and/or how to deal with them.
My main monitor runs with a 1920x1200 resolution on the DVI port.
When I start a 3D application in 3D mode, my monitor turns blank and I have to restart xorg to see anything again.
Recently I added a second Monitor on the VGA port with 1280x1024 resolution. Now I see that I do indeed get 3D fullscreen, just on the wrong monitor.
Usually, when I start Xorg, I get my output on the main monitor and "input not supported" on the secondary.
If I start a fullscreen 3D app, my primary monitor switches off, the secondary on gets the output. When I stop the application, my secondary monitor gets "input not supported" again but my primary monitor doesn't switch on again. I have to restart Xorg.
Then I start both monitors using the following command:
Everything works as it should, as far as I can see.
xrandr --output VGA-0 --mode 1280x1024 --output DVI-0 --mode 1920x1200 --left-of VGA-0
If I now start a 3D fullscreen app, I get the output on the secondary monitor and the primary stays on, I just can't access it with my mouse.
But when I stop the application, my primary monitor turns off!
I can use the command above to get both working again. Only once did I get some sort of bug, when I started an application using the XV extension. The performance got horrible, I could hardly move my windows. But this only happened once.
My second problem is probably much easier and concerns KMS.
My console is only relatively small, occupying a part of my big screen.
I see the message
Can I configure KMS to give my my full 1920x1200 screen? That would be nice!
TV-9: set mode 800x600 30
Despite these problems I am amazed how stable everything is. Even using the XV extension and 3D I have not yet provoked a single hang. I could always switch consoles and to and from X without any problems.