[mythtv-users] Upgrade old or cut my losses and buy new?

Yan-Fa Li yanfali at gmail.com
Wed Mar 7 23:28:25 UTC 2007

On 3/7/07, Yan Seiner <yan at seiner.com> wrote:
> Yan Seiner wrote:
> > The non-working machine, the one with the Sempron, locks up when trying
> > to use agpgart; I have to set option "nvagp" "0" or "1".
> >
> > On looking at the modules, the working machine loads the agpgart and the
> > via_agp modules; it has a KT400 chipset.
> >
> > The non-working machine loads agpgart and amd64_agp.  The kernel docs
> > say:
> >
> > This option gives you AGP support for the GLX component of X using the
> > on-CPU northbridge of the AMD Athlon64/Opteron CPUs.  You still need an
> > external AGP bridge like the AMD 8151, VIA K8T400M, SiS755.
> >
> > So.... First of all, do Semprons have an on-CPU northbridge?  Second of
> > all, should I be loading the via_agp module as well?
> >

AFAIK, all AMD64 based Semprons have a northbridge.  The old Athlon-XP
based ones definitely don't.

> > Or should I be loading *just* the via_agp?
> >
> OK, a bit of testing last night and some changes (not really improvement...)
> If I load the amd64_apg module, I get a hard lock on trying to use AGP
> (nvagp = "2|3").  If I leave that module out, or load the via_agp
> module, I get agp usage, and the stuttering is gone.
> Unfortunately, the video runs in slow motion for a second or two, then
> breaks up slightly, gets caught up, runs in slow motion....
> One other thing I've noticed is that my logfile shows an agp aperature
> of 32 MB even though I have the bios configured for 64 (or 128 or256)
> MB.  Are there any known problems with the Asus K8V SE mobo or the
> K8T800 chipset?

Well there is the well known, "VIA is bad at PCI bus transfers"
problem.  Intel and Nvidia based southbridges appear to be much less
problematic.  For whatever reason VIA has never gotten it's stuff
together and you regularly see people complain about random lock ups
and timing issues with ivtv cards and VIA motherboards.  I wouldn't be
surprised if their AGP is suspect too.

On the other hand I've had good luck with SiS based boards, my
mythbackend has been running an AMD64 Socket 754 on SiS for nearly 2
years.  After a particularly bad experience a few years ago I now run
screaming from VIA based mainboards when I see them in the stores.
They might be okay for running windows, so you *could* load MCE on
there.  Just kidding.

> More and more it feels like a problem with the CPU <-> AGP data flow....
> --Yan
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