Date: Mon, 18 Sep 1995 18:30:56 +1000 From: Bruce Evans <bde@zeta.org.au> To: jehamby@lightside.com, sos@freebsd.org Cc: davidg@root.com, hackers@freebsd.org, vak@cronyx.ru Subject: Re: atapi.c and wcd.c missing.... Message-ID: <199509180830.SAA14431@godzilla.zeta.org.au>
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>> Has anyone reported bugs with the ATAPI support failing for IDE disks? >> If so, which version are you using? If these problems have been >> resolved, I would like to see IDE CD-ROMs supported in the GENERIC 2.1.0 >> kernel (you'll sell more Walnut Creek CD-ROMs for sure :-) Yes. All versions. Not resolved yet. >The 1.3 version is in -current (I committed the patches last week) >And yes it still has problems with some old IDE disks that gets >confused by the ATAPI probestuff. I'm not sure taht this is solvable >at this point... The probe begins with wdreset() which is already weakened (broken) to pass both IDE drives and IDE cdroms. The following bugs in wdreset() are known: 1) it doesn't do a drive select, so it may be reading the status register for a random drive. 2) it only looks at the status register for one drive. 3) if all drives and cdroms followed the specs, then it should be testing for (dk_status == 0x50) (which implies that a drive is attached) || (dk_status == 0x00) (which implies that a cdrom is attached). It actually tests for ((dk_status & 0x50) == 0x00) which passes drives, cdroms, and anything that sets the 0x50 bits to 0x10 or 0x40 and the other bits to 0x00. 4) some drives set the 0x02 bit in dk_status. There may be a problem when wdreset() is called from wdunwedge(). wdunwedge() knows to reset some internal state for drives. It doesn't know anything about cdroms. Bruce
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