pxeboot with amd64 vs i386

[Robert Watson]

I have my first SMP amd64 box at the office now to work with, and thought it 
was all going to be easy.  Sadly not, or at least, not yet. :-)

I configured dhcpd, tftpd, and nfs to export the 6.1 install CD from my 
notebook.  All good so far.  The problem is as follows: if I insert the 6.1 
i386 release CD, it all works great.  If I insert the amd64 CD, then I get the 
following after pxeboot has been going for a bit:

(root at bloom.cse.buffalo.edu, Sun May  7 02:16:38 UTC 2006)
Can't work out which disk we are booting from.Guessed BIOS device 0xffffffff not found by probes, defaulting to 
disk0:
can't load 'kernel'

At that point, lsdev shows the disk devices, but not the pxeboot "disk", which 
leaves me without a kernel, etc.  So something is different between the i386 
and amd64 disks, or maybe there's a problem with my BIOS.  I was wondering if 
anyone else had set up a similar configuration and had it work?

Robert N M Watson