[coreboot] AMD CAR quiz question

Stefan Reinauer stefan.reinauer at coresystems.de
Sun Jun 6 17:28:46 CEST 2010

On 6/6/10 5:01 PM, Rudolf Marek wrote:
> Hello,
> It makes me wonder why CAR on APs use same stack?
Maybe it is not coherent?
Or maybe it doesn't really work?
> I see that Fam10h CAR
> code allocates 1KB for each AP. But not pre Fam10h.
> How this can work?
> Rationale for question is to have some kind of mutex for serial console
> printouts and for Network over console. Secret plan is to print
> outputs from
> different CPUs on different UDP port ;)
> Second reason is that we really need some inter CPU mutex for PCI access.

Or we need to stop doing PCI accesses and console output in SMP before
we have RAM.

I somehow can't imagine that the speed improvements we get from doing
concurrent PCI config space accesses to some 100 registers really make
up for the trouble we get ourselves into by trying to wildly spread
configuration tasks among CPUs (and doing it differently on basically
every mainboard that uses K8 or K10)


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