netlink ?
The missing netlink has been found. The problem was that the box was booting via BOOTP and used nfs root. Net initialization seems to have been deferred and a whole bunch of network related stuff built into the kernel just did not come up right.
Now that I'm booting off the local /dev/sda with the same kernel, things seem much improved. /proc/net has about twice the entries now and netlink works.
Thanks for the excellent kernel port, folks !
cheers, Andy