# Linux sg and sense codes

Matto Marjanovic (maddog@mir.com)
Fri, 17 Dec 1999 02:49:33 -0500

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Hiya, given all the new development in the Linux scsi architecture, I
figured I'd ask about an old thorn in my side (which seems to have
started poking me again recently).

Older Microtek scanners, despite setting the "valid" bit of the first
byte of the sense buffer, return sense codes which bear no relation
to the SCSI-2 standard. A couple of years ago I figured out that
this tended to really confuse the scsi system, which would sometimes
retry commands on its own, and would inevitably *not* return the
sense data to the backend without munging it up in some way.

This is a real nuisance because some scanners try and need to report
that they are busy in certain circumstances, but the message is
always lost. The fact that the scsi system retries the commands on
its own volition just compounds the problem.

Do you know if anything has changed in this regard, or if there are
any ways to circumvent this snag?

Thanks,
Matt M.
(author of the microtek backend)

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