Tagged Queueing and Dque Bit

[Doug Ledford]

On 06-Jan-98 Mike Bilow wrote:
> DME> If a fix is to be made for this, it belongs in the mid-level
> DME> SCSI code.
>
>That makes some sense, but I see no reason we could not at least perform a
>sanity check and warn about any inconsistency.  We're in the middle: if the
>mid-level SCSI code is telling us to do tagged queueing and the device is
>telling us it has tagged queueing disabled, it seems we are in a good
>position
>to notice this and do something about it.

That's a nightmarish prospect, peeking into command request buffers after
completion but before returning it to the mid level code.  No, I don't think
that's a real option.  On the other hand, the latest version of the
seqeuncer and kernel code code that I'm working on from FreeBSD includes
support for detecting drives that claim to do tagged queueing but then blow
up when you send tagged commands.  In that case, the driver disables tagged
queueing internally for that device and sends everything as untagged
commands.  This should be sufficient to solve the problem people are seeing
from these devices.

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E-Mail: Doug Ledford <dledford at dialnet.net>
Date: 06-Jan-98
Time: 13:56:43
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