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
