[Flightgear-devel] FSAA frustration continues (Nvidia forum post)

[Dave Perry]

I posted the following note to the Nvidia linux forum. The issue seems to be an interaction between fgfs and the Nvidia driver.


NVIDIA linux foum post:

I am a FlightGear enthusiast. Over the past year I have run various kernels with all the released nvidia linux drivers and various versions of FlightGear. My experience separates into two categories:
1. No FSAA affect no matter what value for __GL_FSAA_MODE is exported. In this case, Flight Gear runs with no system lock ups.
2. FSAA affect follows the value of __GL_FSAA_MODE while running FlightGear for some versions but not others. But the system ocasionally locks up when changing active windows or active resolutions.

On page 52 of the Nvida Release 25 Notes, the second note indicates that "When FSAA is enabled ... the rendering may be corrupted when resizing the window." This is not a minor inconvenience, for it appears to be the cause of complete system lock ups that force hard resets.

I can run FlightGear from my Windows XP partition (compiled under Cygwin) at all resolutions and all FSAA settings. So why can't Nvidia get this stability in their Linux drivers.

My system is an Athlon XP 1800+ with an Asus A7M266 mother board, 512MB of PC2100 memory and 3 Seagate Baracuda IV (80GB each). My GF3 is an Asus V8200 Deluxe. My Linux is a RH7.3 with recent up2date, but I am running a 2.4.19 kernel compiled from tarball. This kernel has the patch for the speculative cache conflict also mentioned in the Nvidia docs. The behavior described is similar for either the 1.0-3123 or the 1.0-2960 drivers. I always install Nvidia drivers from the source RPMS using the --rebuild switch so that they for sure match the current kernel headers, etc.

What is wierd is that FlightGear 8.0 (recent stable release) runs with no FSAA no matter what value I export for __GL_FSAA_MODE and therfore runs w/o crash. However, the CVS version 0.9.0 runs with FSAA ok with depth 16 and 1600x1200 or 1280x1024. With depth 24, there is no FSAA at 1600x1200 (thus stable runs), but there is FSAA at 1280x1024 resolution. In order to switch from the default 800x600 startup window to a 1600x1200 window, I first must cycle the resolutions (ctrl-alt-"+") and then resize the window. When I use the normal exit option from fgfs, occaionally the system hard locks when i click on the "yes" box.

With depth 16, and any resolution, (1600x1200, or 1280x1024), I must disable the splash screen, or the system locks up 100% of the time when running FlightGear with FSAA enabled.

This is clearly an Nvidia driver bug! Are others having similar issues with complex applications?
- Frustrated Dave



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