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SubjectRe: [VIA Support] Instruction timing and cache coherency issues
Hi!

> Started back in mid-May - long time and a lot of hours later...
>
> As suggested very early in this examination by others -
> It is a timing issue. My inserting "lock" for config_mviac7
> was just poking at the edges of the sore spot. ;)
>
> The "break through" came yesterday while running (or trying to run)
> FreeBSD-8.0-beta2 on the various machines at hand. . .
>
> Depending on the cpu model variation and the integrated chipset
> used with that cpu - -
> *) FB-8.0 will run
> *) FB-8.0 will only run in "safe mode"
> *) FB-8.0 panics
>
> And that pattern is similar to the 2.6.30 cpu model / chipset pattern.
> Scratches head, asking: "now how can that be" with two very different OS designs.
>
> Diddling with the things I have found that either "fix" or "work around"
> the various timing / cache coherency issues - - -
> Aw, so - found how to affect the timing issues sufficiently so that Linux
> would panic dump rather than deadlock on the troublesum combination - -
> *Functionally the same* panic backtrace that FreeBSD is showing.
>
> NOW I have a lead into making a "minimum invasive" change so that the
> kernel is happy - even on the flaky VIA combinations. Patch RSN, just any month.
> The FreeBSD project can fix their problems themselves. ;)
>
> @H.W. Download the FreeBSD-8.0-beta2 and try running it on your Cloudbook and HP-2133,
> you can see what is happening. Then you might have a word or two with the silicon growers.
>

So... you believe you have pinpointed bug in their cpu design?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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