Messages in this thread | | | Subject | Re: PROBLEM: Impossible to read files from a CD-Rom | From | Daniel Pittman <> | Date | Sat, 13 Sep 2003 17:34:57 +1000 |
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On Fri, 12 Sep 2003, Jens Axboe wrote: > On Mon, Sep 08 2003, Samuel Thibault wrote: >> On Mon 18 aug 2003 18:35:22 GMT, Sébastien Hinderer wrote: >> > I'm using a vanila linux-2.6.0-test3. When I try to use a CD-Rom, >> > the mount is successful, so are the calls to ls. However, as soon >> > as I try to read a file, I get a lot of messages such as :
[...]
>> We dug a little bit this Monday with Sebastien, and found out some >> troubles: the call to set_capacity at the end of cdrom_read_toc() >> writes a strange value, which is not always the same, even for the >> same reinserted CD-ROM, seemingly because it came from >> cdrom_get_last_written():
[...]
> I'd be more interested in fixing the real bug: why does your drive > return zero length, and only sporadically?
This sounds somewhat like a problem I have playing DVD-R discs on one DVD drive (Pioneer slot-loader), using Xine and the RAW device.
Basically, for some discs, the raw device cannot read any block, as the capacity of the disc is reported as zero blocks.
I don't have trouble accessing the content on any other machine, though, and can access the files through a mounted filesystem.
/proc/ide/hdc/capacity contains zero in these cases.
Occasionally, for a disc that does this, I get a valid (looking) size, but not very often -- one time in twenty, at most.
I am happy to work on debugging this, if there is anything that can be done to help identify the problem.
This only seems to occur with DVD-R discs, and without any predictable pattern.
Daniel
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