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Date:      Wed, 26 Mar 2003 16:22:09 EST
From:      BelletJr@aol.com
To:        current@FreeBSD.ORG
Subject:   Re: "READ_BIG command timeout" on CDROM drive
Message-ID:  <157.1d8b9c29.2bb37401@aol.com>

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>> Hi all!
>> 
>> When I read cdroms with fbsd 5.0, the following message appears in the 
>> console very often (it seems to happen with every cdrom I try):
>> 
>>>acd0: READ_BIG command timeout - resetting
>>>ata0: resetting devices ..
>>>done
>> 
>> 
>> It is repeated indefinitely and I can't kill -9 the process that is trying 
to 
>> read the cdrom.
>> "umount -f /cdrom" also gets stuck and doesn't write any error messages.
>> 
>> The driver in use is cd9660: RockRidge Extension.
>> 
>> I have to reboot to have access to the cdrom drive again. And besides, the 
>> shutdown process does not end every time when the system is in this state.
>> 
>> Is there a means to have access to the cdrom drive again without rebooting?
>> I have not seen any bug report for this problem; am I right?
>
>Just wanted to report that I fixed this problem by adding:
>
>hw.ata.atapi_dma="1"    # Run the CD-ROM/DVD in DMA mode
>
>to /boot/loader.conf.  The system was trying to access the drive using 
>PIO4 rather than DMA and crapping out.  I got the idea from another 
>thread today with the subject "playing mp3's and burning a cd".  Just an 
>FYI.
>
>-Scott

Thanks for the tip, Scott.

I added the line to loader.conf, rebooted and verified the value with sysctl. 
After plenty of successful read accesses to cdroms, I was about to think it 
corrected the problem on my box too. But unfortunately, it occured again.
It does not happen as often as before; it seems it happens only with cdroms 
holding errors. But the symptoms and the solution (shutdown and reboot) 
remain the same :-(





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