The 855GM-chipset flawlessly works if you're using kernel-version 2.6.38+, the Intel graphics driver 2.16 (without SNA) and Mesa 7.10.3+. Ubuntu 11.04 delivers two of these three things but can update the graphics driver to version 2.16 very easily.
Just because you're using Mesa 7.10.3, it doesn't mean you're using the i810 driver. Furthermore, even if you are, it doesn't mean that the i810 driver doesn't freeze on lots of other hardware/systems other than yours.
What are you talking about? The "i810"-DRI-module was used only for the i810 and i815-chipsets. All other chipsets newer than this use the "i915" (i830 - i945) or the "i965"-DRI-module (i965 and above).
Because of this excerpt from Michaels article:
The only one of these DRI1 hardware drivers that still might be missed by a small portion of users would be the i810 driver, which provides the Intel Mesa support for pre-i915 IGPs. This though shouldn't be a terrible shock. Intel engineers haven't given a damn about the i810/855 series for years since some of this old hardware was already fairly problematic just when it came to mode-setting and there was already a host of DDX issues when migrating to the GEM-enabled KMS-only stack.
Right. Just to be clear: the proposal is to remove support for the original i810, which uses a separate "i810" DRI1 driver. Ian did not propose removing support for i830/845/852/855/865, which uses the "i915" DRI2 driver.
Michael is correct in that all the 8xx chipsets are basically unsupported at this point, though...we might remove 3D support for those at some point in the future (but not today!).
Darn... Still using savage, tdfx and r128 here... I actually find it more satisfying to resurrect old systems than to participate in FPS bragging contests.
Oh well, there are a couple of distros aimed at old HW anyway, there's hoping legacy Mesa will be in maintenance mode through those.