Date: Thu, 25 Feb 1999 18:39:30 +0200 From: Sheldon Hearn <sheldonh@iafrica.com> To: Pierre Beyssac <beyssac@enst.fr> Cc: Greg Lehey <grog@lemis.com>, freebsd-current@FreeBSD.ORG Subject: Re: IDE CDROM not found with PIIX4 chipset, -current kernel Message-ID: <6749.919960770@axl.noc.iafrica.com> In-Reply-To: Your message of "Thu, 25 Feb 1999 17:16:53 %2B0100." <19990225171653.A846@enst.fr>
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On Thu, 25 Feb 1999 17:16:53 +0100, Pierre Beyssac wrote: > I tried to find out why it worked with a Linux kernel by comparing > our IDE code and theirs, but it was way beyond my comprehension. > I'm not trained for the black magic of IDE probing. I used this particular issue for the launch of my first adventure into serial console kernel debugging. Multo fun. I can offer you two interesting points: 1) I have an ATAPI drive that FreeBSD 2.2-STABLE won't detect on boot if it contains a disc. 2) I found that stepping through the kernel caused exactly the same problems I was having with accessing my one ATAPI drive that I experience just running normally with my other drive. So it looks like at least one problem regarding ATAPI has to do with timings. So far, the conversations I've had with clueful FreeBSD hackers have led me to accept the following: A) The ATAPI standard is weak and the variety of implimentations thereof is even worse. B) The odds that your ATAPI CDROM drive will behave predictably in accordance with said standards are directly proportional to its age. It seems that newer (24xspeed+) drives suck. C) The ATAPI code in FreeBSD is about as good as our hackers care to make it, given the demotivating impact of A and B above. I spent a good few days stepping around my kernel over serial connection, using a "working" 4xspeed drive and a "broken" 36xspeed drive and testing a reproducible fault with cdcontrol. I'm a pretty stubborn guy, but I gave up. Ciao, Sheldon. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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