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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