On Mon, Dec 03, 2012 at 03:17:26PM -0500, Peter Gavin wrote: > Another problem is that l.nop REPORT requires that register 3 be read by > the pipeline. That's not possible without heavily altering the pipeline > design--the register addresses accessed by any given instruction need to be > available immediately without any decoding overhead. So if we introduce a > debug UART we need to rethink the instructions used to output to it. I > would suggest adding a separate instruction just for that purpose.
How is that any different than any other instruction that is using registers as source for their data? I agree that there will be some overhead if actually implemented in hardware, but so would any other instruction outputting to a debug uart. Or am I completely missing your point here? Stefan _______________________________________________ OpenRISC mailing list [email protected] http://lists.openrisc.net/listinfo/openrisc
