Re: kern/38643: [dM] st tape drive loses data

[der Mouse <mouse%Rodents-Montreal.ORG@localhost>]

I tried (a) rolling back my concurrency change to physio and (b) making
stread and stwrite use statically allocated structs buf for their calls
to physio.

The results: the same as the concurrency change to physio.  That is, it
loses one tape record, instead of 15, when reading.  (I found a scratch
tape, so I was able to do a proper test, which also confirmed the
behaviour with the concurrency override in physio.)

In my Copious Spare Time, I hope to be able to try this with some of
the debugging printfs I see scattered around the st and scsipi code
turned on.  If-&-when I manage that, I'll report back.

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