Tyan S3950 and amd64 FreeBSD fails on bootup

[Adrian Gschwend]

Dear group,

I got a problem with a new AMD Opteron box, when I bot FreeBSD 6.1
(amd64) I get this:

fBSD/i386 bootstrap  revision 1.1
kernel text=....  data=.... sym=....
at-xy not found
[regdump]
BTX halted

I've put a (very bad) screenshot online here:
http://www.hta-bi.bfh.ch/~gea2/freebsdamd.jpg

It's a Tyan S3950 Mainboard which is on the list of devices that work at
least for some people:

http://www.freebsd.org/cgi/query-pr.cgi?pr=104661

Specs of the machine:
*  CPU: AMD Dual Core A64 X2 4200+ / 2x2200MHz / 2x512KB Cache
* Motherboard: TYAN 3950 AM2 with VGA / 2x Gbit Intel LAN (4 DIMM)

I use a 3ware SATA RAID controller, the onboard one does not have to
work and is on PATA compatibility mode already for the CDROM.

I've booted this CD image: 6.1-RELEASE-amd64-bootonly.iso

I couldn't find anything useful with google or in the release
notes/errata. Interestingly I can't find *anything* useful for the
"at-xy not found" error message (which is really happening like this).

The vendor ships a SUSE Linux with this box which works fine, also
Fedora 6 amd64 boots just fine on it.

I'm a bit lost now, especially because I cannot even disable anything in
the kernel like this. So any hints would be appreciated.

cu

Adrian