[coreboot] AMD CAR quiz question

Rudolf Marek r.marek at assembler.cz
Sun Jun 6 17:01:16 CEST 2010


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Hello,

It makes me wonder why CAR on APs use same stack? How does this can work? I
thought CPUs somehow keep caches coherent between them. 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.

In principle is correct that all CPUs once after CAR stage share the cache contents?

Thanks,
Rudolf
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