SCSI direct
7 messages in this thread
What's SCSI "autosense", and what does it have to do with SCSI direct
programming?
John,
When a program issues a SCSI-direct command, there is a flag-bit that
can be set for autosense – what this means is that if there is an error
encountered, the device driver will automatically issue a SENSE command and
return that information into the buffer provided. Without auto-sense,
there is a possibility of "missing" the SENSE data (particularly in a
multi-tasking environment), since it is forgotten by the SCSI device as
soon as the next SCSI command in encountered.
In the little SCSI-direct hacking I've done, I've not used autosense.
This meant that I had to issue the SENSE command myself when I received an
error return from the "main" SCSI command. The original error doesn't
really tell you much – it's the SENSE bits that really tell what the error
is.
Does this make any sense?
– BobR
It sounds like like it could be handy for detecting errors… Which
references have you consulted for your SCSI direct endeavors?
References? Who needs references? <grin>
Actually, I'm not aware of any references for SCSI direct, other than
what's in the include files (devices/scsidisk.h), which is not a heck of a
lot of information. I started with other people's code that implemented
some SCSI-direct stuff along with the documentation that I got with my
tape drive, which spec'd the SCSI commands that it supported. Just
started hacking away and began to 'see the light'.
I later picked up a copy of the SCSI-II spec (which I converted to Amiga
text format from the awful WordStar format that it was distributed in and
uploaded to the Libs in this forum).
Hope this helps….
– BobR
(Motorola Inside!)
Hee hee… a week or two ago, I was at a bachelor party for a friend, we
started talking about tattoos and we thought we'd get our friend drunk and
get him a little green "Intel Inside" tattoo. He has about as much
affection for it as, say, Ben does. 🙂
With friends like you, who needs enemies?
Bob,
Try the latest Devices RKM. It has a chapter describing the SCSI/SCSI
direct information. There really isn't much there, but it's more than what
you get out of the includes.
Dean
DKB Software