In Rockbox we’ve seen the gcc 4.2.x series introduce warnings on C code that really is perfectly fine, and also compiles warning-less on all other versions of gcc. (We use the 4.2.x series in Rockbox only for the simulator, built for running on host.)
In the linux-mips project, they’ve found gcc 4.2.2 to not even be able to build their kernel…It has been suggested that perhaps the best thing is to just skip to 4.3. Bugzilla entry.
MrH updated his Semi-Independent DMA Interface docs for the PortalPlayer PP5024, now at 0.6.