Wolfgang, Joakim, > I have to admit that I didn't believe our customer when he > reported that he has problems that were caused by the CPU15 > bug - I never saw this on any other 8xx processor before, and > as you say it has been mentioned in all errata sheets I > can remember. As far as I can tell it is only the MPC870/885 > duet family of processors where this CPU15 bug actually > hits. I have no idea why.
CPU15 is highly timing dependent. Even a single clock difference in the bus interface can make it (dis)appear. It can happen on Duet's as on any other 8xx ... or not. The simple workaround of invalidating the prev/next page is exactly that. Simple. It works, but for code with page locality it can hurt performance because you would get excessive reloads. A smarter workaround affecting only pages that need the workaround is preferrable, if it fits into the MMU table framework. Heinz
