[coreboot] [PATCH] [sort of] multiplex console output from each core

xdrudis xdrudis at tinet.cat
Sun Jan 30 22:29:55 CET 2011


On Sun, Jan 30, 2011 at 01:05:54PM -0700, Marc Jones wrote:
> 
> I think that the locking can be added via the BSPs cache. All
> multicore should use CAR and it is a matter of adding it where it
> won't get stepped on by the normal use of CAR. For AMD fam10, the
> sysinfo setup would need to be fixed up.
> 
> Marc

That is a little over my head, I believe. I thought in general the
cache was a different memory for each core (let alone each node).  My
phenom has L3 cache common to all cores but I thought romstage is not
using it.

And I guess the functionality is slightly different :

with muxing you get the node number in the output so you can format
things in columns, etc. And it is not dependent on the architecture
(except to find out the core number to use as buffer id).  With
locking you just separate output but don't know which core it comes
from (but it becomes feasible to include the core number in the
messages where appropiate, and you don't need demuxing, get less
serial traffic...).

locking in romstage might be useful for other things beyond console 
output, though. 

So both approaches have advantages. I'm just not sure how to implement
locking. That's the main reason I didn't, even if some comment
suggested it somewhere. Secondary excuses were that it seemed less
alteration of the runtime behaviour not to lock, and that I could also
set it up to filter out some output.




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