This probably isn't too far off... basically we will need either a separate address space or a partition of the current space for these messages, and given that we have 64 bits to play with a partition doesn't seem unreasonable. I think I was reacting more to the ad-hoc appearance of the code than to the conceptual approach.
Steve On Jan 29, 2011 3:24 PM, "Gabe Black" <[email protected]> wrote: > This, plus the patches I fixed up for Joel and Brad, plus the reviews I > just sent out (and some new stats and a new disk image) get X86 FS > regressions going. It didn't sound like we had really reached consensus > on whether what I was doing here was a good idea, though, or if there > was a better idea. Any comments? Basically the unique issue here is that > messages need to be able to pass back up from the IO subsystem to the > CPUs for MSI-esque interrupts, so there needs to be a path for those > through the bridge/small cache thing attaching the IO bus to the memory > bus. If all that was needed is a comment then that's easy, but it > sounded like you weren't in favor of the general approach, Steve. > > Gabe > > > Gabe Black wrote: >> A number of prefixes can be stuck into the top nibble of a physical >> address to put it into a partition set aside for a certain purpose. This >> is something I'm doing in M5 that isn't directly analogous to a real >> system, but I suppose it would be similar to extra signals on the bus >> for the same purpose. The CPU can only generate so many physical address >> lines (less than 64) so there shouldn't be any collision. The partition >> with prefix 0 is normal memory, devices, etc. so they don't have to be >> treated specially, and one of the others is for the APICs to talk to >> each other. And yes, a comment would be a good idea. I didn't want to >> put on all the trimmings if this was a dead end. >> >> Gabe >> >> Steve Reinhardt wrote: >> >>> My initial reaction is "even if this works, this can't possibly be the >>> best way to do it"... where do APIC messages live in the address >>> space? How does 'Addr.max >> 4' let them through? Did you really >>> think this change didn't need a comment? ;-) >>> >>> On Tue, Nov 23, 2010 at 3:39 AM, Gabe Black <[email protected] >>> <mailto:[email protected]>> wrote: >>> >>> This seems to get APIC messages back to the CPU, but I really >>> don't know >>> if it's the right way to do this. I have the feeling there are >>> forces at >>> work in this code I don't fully appreciate. >>> >>> Gabe >>> >>> Gabe Black wrote: >>> > This is an automatically generated e-mail. To reply, visit: >>> > http://reviews.m5sim.org/r/323/ >>> > >>> > >>> > Review request for Default. >>> > By Gabe Black. >>> > >>> > >>> > Description >>> > >>> > Mem,X86: Make the IO bridge pass APIC messages back towards the CPU. >>> > >>> > >>> > Diffs >>> > >>> > * configs/example/fs.py (865e37d507c7) >>> > >>> > View Diff <http://reviews.m5sim.org/r/323/diff/> >>> > >>> > >>> ------------------------------------------------------------------------ >>> > >>> > _______________________________________________ >>> > m5-dev mailing list >>> > [email protected] <mailto:[email protected]> >>> > http://m5sim.org/mailman/listinfo/m5-dev >>> > >>> >>> _______________________________________________ >>> m5-dev mailing list >>> [email protected] <mailto:[email protected]> >>> http://m5sim.org/mailman/listinfo/m5-dev >>> >>> >>> ------------------------------------------------------------------------ >>> >>> _______________________________________________ >>> m5-dev mailing list >>> [email protected] >>> http://m5sim.org/mailman/listinfo/m5-dev >>> >>> >> >> _______________________________________________ >> m5-dev mailing list >> [email protected] >> http://m5sim.org/mailman/listinfo/m5-dev >> > > _______________________________________________ > m5-dev mailing list > [email protected] > http://m5sim.org/mailman/listinfo/m5-dev
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