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Date:      Wed, 29 Jan 1997 12:55:07 -0800 (PST)
From:      Simon Shapiro <Shimon@i-Connect.Net>
To:        freebsd-scsi@freebsd.org
Subject:   XXXminpys question
Message-ID:  <XFMail.970129132302.Shimon@i-Connect.Net>

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When/how is the minphys entry point in an HBA driver called?

All we see in the bt and ahc drivers is a comparison between a buf and a
constant.

In the driver we are writing now, mulltiple controllers, all run with the
same driver, can EACH have their own minphys.  Actually, like others, it is
limited by the scatter-gather DMA engine.  The cheapest HBA can have 16
segments in the DBA S/G.  The largest can have 8192 currently.  May grow
larger.

What we need, in addition to the clarification above is these answers:

a.  Does minphys get called for each I/O request, with that I/O's own buf?
b.  Does minphys get called, at initialization time, once per HBA?
c.  Does minphys get called only once for ``the driver''?

If A is true, we can (nasty) extract the HBA from the device data in buf.
If B is true, we need some indication in calling minphys as to which HBA.
Ic C is true, we have a problem.  In that case, can we manipilate the buf
structure when the SCSI command is called in and do only partial I/O by
manipulating the b_count and b_resid fields?

This is sort of a stalling stump for us so soon response will be
appreciated...

Thanx!

Simon



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