It appears that the problem discussed below results from having
both udma and non-udma devices on the same wdc channel.  An immediate
workaround is to set the 0x0f00 flag on your wd(4) device to
disable fUDMA.  This is the line you would change in your config file:
	wd*	at wdc? channel ? drive ? flags 0x0f00

I am in the process of testing a patch which should fix this
problem in a better way.

Darrin

dbj@netbsd.org writes:

> I have a 500 Mhz dual usb ibook with the combo dvd/cd-rw drive.
> Both the 20011111-1.5Y snapshot and -current sources from the
> 20011210 tarballs exhibit the same behavior which prevents
> me from using the CD drive.
> 
> Accessing the cd drive with either the disklabel or mount command
> results in the following console message and then a hung system:
> 
>  # disklabel cd0
>  wdc:0:0:1: lost interrupt
>           type: atapi tc_bcount: 32 tc_skip: 0
> 
> I can access wd0 fine and have been able to install over the
> network interface and use the rest of the system normally.
> 
> I have included the dmesg output below taken from
> booting the 20011111-1.5Y snapshot.
> 
> Darrin
> 
> : Subject: Re: 1.5.2 hangs on iBook2 when mounting cdrom
> : To: Laurent de Segur <ldesegur@mac.com>
> : From: Nathan J. Williams <nathanw@wasabisystems.com>
> : List: port-macppc
> : Date: 12/07/2001 13:09:01 
> : 
> : Laurent de Segur <ldesegur@mac.com> writes:
> : 
> : > The machine is the iBook2001 first gen (500/66) and before it dies the
> : > kernel spits a message stating that it missed an interrupt. That can't
> : > be good.
> : 
> : This is the ATA timing issue in wdc_obio.c that was fixed by Manuel
> : Bouyer in August (rev 1.16 of wdc_obio.c is the crucial one). 
> : 
> : > Has anyone seen that? Is the snapshot dated 111101 works better? I am
> : > going to try that after. Thanks for letting me know,
> : 
> : This should work fine in the 11 November snapshot, yes.
> : 
> :         - Nathan