> There are two major problems with using the DmaPort. First, I'd want to > send the interrupt -now- not when the DMA queuing latency, etc gets used > up. Second, DmaPort will fragment a packet which, while maybe necessary > in some cases, will break the atomicity requirements for the interrupt > messages and might even make the parts of it get there out of order. > While it may not -normally- fragment the message, if it does things will > be broken. I would rather not use something where such a large portion > of its functionality is either not needed or counterproductive.
Yes, you want to send the interrupt now, but in the real machine there is a propagation delay and things will have to arbitrate for the system bus. Nobody has dedicated interrupt pins anymore. So, it is much more realistic to use a DmaPort. Also, as Ali said, the DMA port will only fragment if it is longer than a cache line. We can add some sort of flag to a request that says "Don't Fragment" that will raise an assertion if somethign wants to cause fragmentation. Nate _______________________________________________ m5-dev mailing list m5-dev@m5sim.org http://m5sim.org/mailman/listinfo/m5-dev
