System lockup during dump()

[Richard Earnshaw <rearnsha%buzzard.freeserve.co.uk@localhost>]

I'm trying to track down why a Cats box just freezes when trying to do a 
panic dump.  Turning on the wdcdebug code shows the following activity:

db> sync                                                                   

boot: howto=00000100 curlwp=0x0                                            

syncing disks... done                                                      

__wdcwait aceride0:0 (timeout:1)                                           

wdcintr                                                                    

__wdccommand_intr aceride0:0:0                                             

__wdcwait aceride0:0 (timeout:0)                                           

                                                                           

dumping to dev 16,1 offset 789199                                          

__wdcwait aceride0:0 (timeout:1)                                           

wdcintr                                                                    

__wdccommand_intr aceride0:0:0                                             

__wdcwait aceride0:0 (timeout:0)                                           


after which the machine just goes catatonic until the reset button is 
pressed.

What gives?  I thought that the dump was supposed to be done with POLL 
operations, so why is wdcintr being called?

R.