From: utzoo!decvax!ucbvax!info-vax
Newsgroups: fa.info-vax
Title: overlapped seeks
Article-I.D.: ucbvax.7912
Posted: Mon Jul  5 23:51:20 1982
Received: Tue Jul  6 04:17:35 1982

>From dove@mit-dspg@mit-mc Mon Jul  5 23:50:55 1982
On an old emulex controller we had a problem with overlapped seeks.  The
problem was that the controller could interrupt due to seek completion
even when a different drive was busy with a transfer.  Since the driver
assumed dec hardware which blocked such seek interrupts for the duration of
the transfer, when it got the seek interrupt, it assumed that the transfer
had completed, and everything broke!  Our fix was to check in the interrupt
routine for controller ready.  If not, go to the end of the interrupt
routine where the rmustart routine is called for each drive with as set.