K8 northbridge f1 behaviour.

Stefan Reinauer stepan at suse.de
Thu Jan 8 16:40:01 CET 2004

* ron minnich <rminnich at lanl.gov> [040108 18:22]:
> What I don't understand is this: if, after booting, I use setpci to set
> c0.b to 0, the system as a whole continues to work fine. If I set c0.l AND
> c4.l to 0, then the system works. I would expect the system to die as I/O 
> no longer would be routed to HT link #2. 
> What am I missing? This is a system booted nosmp, so all I/O should be 
> going through cpu 0 and 0:18.1 settings should control I/O. Is there some 
> 'magic' to make these settings really set into the chip? 
Do these registers maybe want an LDTSTOP_L or a reset asserted to become

Are you sure your other operations do access the VGA ports at all and
don't operate on the graphics device directly?

> I've run into this as we are trying to get vga to work under linuxbios
> using the emulation code (freebios/util/vgabios/testbios). We have
> actually got this code close to working on the normal bios, and have even
> made an nvidia card come up correctly in the agp slot, but we can't get
> vga enables set up so that I/O to the legacy VGA ports works under
> linuxbios.
I got an S2880 up with VGA by using the ATI biosless patch for 2.4.x
done by some SGI guy. That is not really flexible, but it helped me to
see light for the first time in LinuxBIOS


     Stefan Reinauer, SUSE LINUX AG
Teamleader Architecture Development

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