[coreboot] coreboot_apc woes

Stefan Reinauer stepan at coresystems.de
Fri Feb 26 02:11:12 CET 2010

On 2/26/10 12:05 AM, Myles Watson wrote:
> Besides complicating the build system, how much work is it to fix?  My vote
> would be to fix it, since it worked in newconfig.

How much time did it actually safe us?

I'm not sure the AP handling on K8/FAM10 ever "worked" reliably... we
had some reports of PCI access race conditions for example.
Then there is the output locking problem in romstage that hasn't really
been fixed.

So, there is more than one reason not to keep the other CPUs doing stuff
before RAM is up.. Dropping this facility will certainly increase
reliability of coreboot significantly.

Just fixing it up so it works as well as it did before is easy.

Fixing it in the sense of the word is a lot more work and I'd love to
see if it's worth it. i945 does a similar thing like DQS (called rcven)
and it  takes a few ms at best. Sure, milli seconds are evil and slow,
but if we have to do decent inter-cpu-locking in romstage, it sure won't
fly either, just get a whole lot more complicated.

So... who knows actual numbers...?

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