What happend when a texture rendered with the frame buffer object extension get kick out of video memory (not used for long time + many other textures loaded in video memory )? What happend to its content? Does the driver save it automatically in system memory or the texture data is just lost.
To me, it is not possible to loose a texture due to lack of video memory, instead you won’t be able to create more textures.
If this happens it should be copied to system memory, the results will be totally transparent to you, (this is OpenGL, not D3D), you won’t be able to tell although too many copies to and from system memory may hurt performance so you should be wary of oversubscribing memory. The details are entirely implementation dependent, it’s up to the driver writers. Some drivers have been caught behaving badly though.