Date: Sat, 20 Jun 1998 21:05:37 -0600 (MDT) From: "Kenneth D. Merry" <ken@plutotech.com> To: jonny@jonny.eng.br (Joao Carlos Mendes Luis) Cc: ken@plutotech.com, mjacob@feral.com, julian@whistle.com, jonny@jonny.eng.br, ckempf@enigami.com, freebsd-scsi@FreeBSD.ORG Subject: Re: Rolling CAM in, what is still needed? Message-ID: <199806210305.VAA20485@panzer.plutotech.com> In-Reply-To: <199806191742.OAA02683@roma.coe.ufrj.br> from Joao Carlos Mendes Luis at "Jun 19, 98 02:42:45 pm"
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Joao Carlos Mendes Luis wrote... > #define quoting(Kenneth D. Merry) > // - the problem is that with the old SCSI code, to send SCSI commands > // directly to a device, you opened the device itself (/dev/rcd0a or > // whatever) and did the SCIOCCOMMAND ioctl on that device. CAM does > // things differently, primarily because users may want to send > // commands to device, even though the device's open() routine may > // fail. For instance, you can't open a CD device if there is no > // media inserted. But the user may want to send an INQUIRY command > // to the drive, whether or not there's a CD in the drive. So, to > // solve this, you have two choices: (that I can think of offhand) > // - have a special control minor number for each device, and > // have the open call ignore failures in read capacity, test > // unit ready, etc. > // - have a separate passthrough driver that doesn't have to > // have any commands succeed to attach or open. > > Isn't this what /dev/xxx.ctl does ? My guess is that that is what it was supposed to do in theory, but in practice, I don't think it does. I looked at the open routines in the current cd, sd and st drivers, and none of them check to see if it was the control device that was opened. So if no media is in the drive, the open will fail. Ken -- Kenneth Merry ken@plutotech.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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