Date: Sun, 17 Feb 2008 18:12:27 +0100 From: Thomas Quinot <thomas@FreeBSD.ORG> To: Andriy Gapon <avg@icyb.net.ua> Cc: freebsd-gnome@freebsd.org Subject: Re: hal and "criss-crossed" atapicam Message-ID: <20080217171227.GA45284@melamine.cuivre.fr.eu.org> In-Reply-To: <47B86836.8090407@icyb.net.ua> References: <20080217144704.GA38221@melamine.cuivre.fr.eu.org> <47B86836.8090407@icyb.net.ua>
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* Andriy Gapon, 2008-02-17 : > On the other hand, is it possible for atapicam to somehow query > underlying ATA channel numbers and hard-derive unit numbers from that ? > Something like ATA layer does when ATA_STATIC_ID kernel option is given. > Well, maybe this is not applicable to atapi, so I might be just mumbling > nonsense here. Well the main issue here is that the unit numbers are not assigned by ATAPI/CAM but by the CAM subsystem, ATAPI/CAM just provides a transport layer, and it would be a violation of abstraction to special-case ATAPI devices in the CAM device drivers. > No, no :-) HAL actually sees 4 devices, but its default behavior is to > be smart and protective and to mark atapi devices as "ignored" if they > have atapicam partners. Well this sounds a bit questionable to me. If the user wants to take the responsibility of enabling both acd and cd in the same kernel, there is no reason to try to outguess him and disable half of the devices he configured his system for. Also note that what is specifically advised against in the atapicam man page is not enabling both interfaces (which can come in handy -- neither interface claims complete superiority over the other, each has merits of its own and a preferred domain of applicability), it's only *simultaneously* accessing the same device using the two interfaces. > As the manual page warns, it is indeed a bad thing to access the same > device via two interface simultaneously. And hald is very active at > tasting devices, so people experienced crashes and other weird things. You shouldn't count on inquiry data being consistent between ATA and ATAPI/CAM as some devices report different data for both. Example on this host: (root@melamine) ~ # atacontrol list|grep DVD Master: acd0 <PHILIPS DVD+/-RW DVD8701/5D24> ATA/ATAPI revision 0 (root@melamine) ~ # camcontrol inq cd0 pass4: <PHILIPS DVD+-RW DVD8701 5D24> Removable CD-ROM SCSI-0 device Thomas.
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