6.0 kernel will not boot past atkbd0

[Pete French]

Having successfully upgraded one system in-place from 5.4 to 6.0 I had a go
at the second system today. This is an old Compaq proliant 1600R with
two 500mhz pentium3's in it. Currently running 5.4 quite happily.

so I buildworld, buildkernel, insall kernel and rebooot to check that
the kernel works...

...and the new kernel will not boot past the point where it says
atkdb0: [GIANT LOCKED]

(under 5.4 the next thing I get is psm0 for the mouse.)

My kernel is (almost) a generic SMP one - the only changes are that I
have removed INET6 and all CPU's apart from I686_CPU.

I have tried booting this in 'safe' mode, and sevarl other options from
the beatsie menu, but no dice. I havent yet tried a straight 'GENERIC'
kernel, and given the time of night wont be able to until tomorrow, but
am very puzzled as I havent seen anything like this before.

Does anyone have any hints or suggestions as to what I might try ?

-pcf.