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/>
>>     >
>>     >
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