Date: Mon, 21 Jul 1997 11:23:35 -0600 From: "Justin T. Gibbs" <gibbs@plutotech.com> To: Michael Smith <msmith@atrad.adelaide.edu.au> Cc: hlew@www2.shoppersnet.com (Howard Lew), rb@gid.co.uk, hackers@FreeBSD.ORG Subject: Re: Iomega Zip Message-ID: <199707211723.LAA12093@pluto.plutotech.com> In-Reply-To: Your message of "Sat, 19 Jul 1997 14:11:36 %2B0930." <199707190441.OAA12625@genesis.atrad.adelaide.edu.au>
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>Howard Lew stands accused of saying: >> >> The probe doesn't look right, but it works: > >The probe is _exactly_ right. > >> sd0 at scbus0 target 5 lun 0 >> sd0: Direct-Access >> sd0: ILLEGAL REQUEST asc:24,0 Invalid field in CDB >> sd0 could not mode sense (4). Using ficticious geometry > >The drive has refused a MODE SENSE command, so it's not possible to >establish its geometry. Geometry is only (really) relevant for >processing the MBR. Instead, the driver will fake some sensible >falues. Actually, the probe is what you should expect from the current SCSI code, but the current SCSI code isn't really right. It should be using the READ CAPACITY command in order to determine the size of the disk and not even bothering to attempt to get the geometry from the mode pages. In the case of a PC, you want the controller to tell you the geometry to use, based on the size of the device, since the one the drive will give you (assuming it supports that mode page) is quite useless. On other architectures, you may not need a specific geometry as specified by the controller (in PC land, this is only required in order to setup the partition table so you can find the boot block), but it would be trivial to have a generic and efficient geometry placed in the disklabel. In general, it would be nice if no layer above the device driver cared about the geometry of the device and that all BSD partitioning could be performed on arbitrary sector boundaries. >-- >]] Mike Smith, Software Engineer msmith@gsoft.com.au [[ >]] Genesis Software genesis@gsoft.com.au [[ >]] High-speed data acquisition and (GSM mobile) 0411-222-496 [[ >]] realtime instrument control. (ph) +61-8-8267-3493 [[ >]] Unix hardware collector. "Where are your PEZ?" The Tick [[ > -- Justin T. Gibbs =========================================== FreeBSD: Turning PCs into workstations ===========================================
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