On 2008-08-14, Timothy Normand Miller wrote: > Another goofy thing that we're going to have to think about... > > The S3, when doing memory access, relies on reads being in even > numbers of 32-bit words. So if we turn caching off, but HQ is not > running, then a memory read will turn into a single-word request, > which the S3 won't handle correctly. I think I may not try to fix > that, though. > > Basically, we can only turn off memory caching if HQ is intercepting > traffic. If HQ gets a single word read request from memory (and it > doesn't have it cached somewhere), then it must make at least a 2-word > request to the S3 and then return the correct half of what comes back.
I was just about to start the assembly for target read when I got your message, but for simplicity I ignored this and put a comment in the source for the time being. Does this also mean the address sent to the bridge must always be even for reads? Another goofy thing: It seems tricky at best to unroll the transfer-loop for target write. The reason is that we only know the number of queued commands, but what we need is the number of queued write-data commands. Any idea? _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
