Date: Tue, 23 Jun 1998 15:43:34 +0930 From: Greg Lehey <grog@lemis.com> To: "Kenneth D. Merry" <ken@plutotech.com>, Joao Carlos Mendes Luis <jonny@jonny.eng.br> Cc: mjacob@feral.com, julian@whistle.com, ckempf@enigami.com, freebsd-scsi@FreeBSD.ORG Subject: Re: Rolling CAM in, what is still needed? Message-ID: <19980623154334.A392@freebie.lemis.com> In-Reply-To: <199806210305.VAA20485@panzer.plutotech.com>; from Kenneth D. Merry on Sat, Jun 20, 1998 at 09:05:37PM -0600 References: <199806191742.OAA02683@roma.coe.ufrj.br> <199806210305.VAA20485@panzer.plutotech.com>
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On Sat, 20 June 1998 at 21:05:37 -0600, Kenneth D. Merry wrote: > 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. This matches my experience. Greg -- See complete headers for address and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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