Re: Possible critical VIA vt82c686a chip bug

From: Vojtech Pavlik (vojtech@suse.cz)
Date: Thu Oct 26 2000 - 09:01:46 EST


On Thu, Oct 26, 2000 at 03:58:21PM +0200, Yoann Vandoorselaere wrote:

> > I've found a bug in my VIA SuperSouth (vt82c686a) chip (ISA bridge
> > revision 0x12, silicon rev CD) on my FIC VA-503A rev 1.2:
> >
> > When there is heavy disk activity (several tars running concurrently on
> > UDMA66 drive, or tar'ing from one UDMA66 drive to another over two
> > channels), the system time, namely gettimeofday() goes crazy - now and
> > then it advances the time about 1:20 for a fraction of a second and then
> > changes back to normal time.
> >
> > This causes X to blank the screen when it should not,
>
> Really strange, I'm getting exactly the same problem on a machine
> with the same chipset...

Could you send me your 'lspci -vvxxx' to confirm it's the very same
chip?

> > Now I'd like to know if I have a faulty chip, faulty motherboard or
> > whether this problem exists in more chips as well.
>
> I've changed my motherboard thinking it was a default of it.
> it is not.

Ok, so this means it's not the motherboard and it's not just my chip.

> > If anyone owning a motherboard with the vt82c686a chip (VIA with UDMA66
> > and audio), could test this, I'd appreciate that.
>
> I've this kind of motherboard without audio.

Well, the audio function is integrated in the chip, possibly just disabled.

> > Attached is a patch that makes the problems go away by reprogramming the
> > chip in the problematic case.
>
> I'll try it ASAP, then do a feedback.

Ok, thanks.

-- 
Vojtech Pavlik
SuSE Labs
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