According to Juergen Hannken-Illjes:
>
>Please check if your `/sys/kern/subr_disk.c' is at least Rev 1.27 (Jan 28, 2000).
>

I have updated the source on my machine at home, built a kernel and
loaded it onto the laptop - it still hangs, the odd thing is that the
HD seems to shutdown, the disk stops spinning but the HD led stays
on.  I have done some digging around on the _old_ source (updating the
laptop source is risky, given the disk habit ;-) and I have noticed
there is a loop in wdc_exec_command in /usr/src/sys/kern/ic/wdc.c that
waits on AT_DONE and tsleep's if the status is not AT_DONE straight
away - I am suspicious of this loop, I tried putting a count into the
loop to break it out after a number of times around, this changed the
behaviour as I was able to do a "make depend" whereas before this
would lock the machine up.  The machine still locked when I tried
making a kernel with -j10 which makes be suspect there is some timing
sensitive problem that happens to be hit with the combination of
hardware I have at the moment :-(

-- 
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Brett Lymn, Computer Systems Administrator, BAE SYSTEMS
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