I own an Acer Travelmate C100 tablet PC with the Silicon Motion SM720 Lynx3DM card that came with it. It is currently running Ubuntu 8.10. Or trying to, at least. I had once tried to run Fedora 9 on it, but it experienced issues with its X server. I didn't have time at the moment to sort that out, so I tried Ubuntu 8.04 again and things worked.
Now I've upgraded to Ubuntu 8.10 and I am experiencing the same issues. A laptop that used to work just fine now encounters the following error, and X refuses to start.
AddScreen/ScreenInit failed for driver 0
I initially tried a variety of difference changes to my Xorg.conf file which did not help my situation. So, I did some investigation, some toying with source code, filed bug 18816 at FreeDesktop.org and wrote to the Xorg mailing list. Franscisco Jerez took interest, indicating that the issue with my driver in Ubuntu 8.10 was probably fixed in git. It seems to have been, but other issues continued to exist. I also have to add the following to my /etc/X11/xorg.conf file:
Option "UseBIOS" "off"
After this, my screen displayed, but was out of centre and flickered. He provided another patch for that. Afterward, I could start X after a fresh power cycle or resume and have a fully functional X server again. Yay!
However, now that I'm using 8.10, I notice a bunch of lag. It seems that when some dialogues open, the screen freezes for 3 or 4 seconds and the content of the dialogue frequently remains just white. I tried disabling acceleration in my xorg.conf (using 'Option "NoAccel"') and in a brief session after this, I didn't get the pauses any more (but acceleration was missing in obvious situations, such as moving a translucent terminal window). I'll try to better test whether XAA acceleration is causing the slownes. Hopefully Francisco or another developer might take an interest in that problem too, if XAA seems the likely culprit :D
So, my upgrade to Ubuntu 8.10 has been fairly painful. My tablet's portable CD-ROM isn't very reliable for reading CDs for installation, and the tablet doesn't boot from USB, so I usually install Linux on it over the network. This makes it difficult to try a different distro. Oh, and my wireless doesn't work anymore. I historically use a Netgear prism2 USB wireless adapter. Try to figure that one out to. So, the moral of the story? Don't upgrade ;)
Francisco Jerez is awesome and I (and others) should totally buy him as much non-alcoholic beverage of his choice as he ever wants.