Re: libata: CD and dvd devices not recognized

[Albert Lee <albertcc@tw.ibm.com>]

Alan Cox wrote:
>>We have two possible solutions here:
>>a. Patch Ubuntu, such that the incorrect INQUIRY is fixed.
>>b. Patch kernel, such that the AOpen drives are blacklisted.
>>   Each INQUIRY is inspected for the blacklisted drives.
>>   If the INQUIRY looks wrong, the INQUIRY is rejected.
>>
>>I guess a. is the preferred solution...
> 
> 
> We have two problems here
> 
> #1 Ubuntu got the inquiry command wrong
> 
> #2 Until now we considered "INQUIRY" a safe command for SG_IO passthrough.
> 
> We can't really take INQUIRY out of SG_IO so do we decide its the
> hardware vendors problem or do something cleverer in the filters ?
> 

Maybe the SG_IO author has better idea (ccing Doug)?

BTW, in addition to the AOpen "INQUIRY with EVPD" problem, we have
another imperfect ATAPI drive (TORiSAN) that freezes when "READ >= 128KB".
(http://bugzilla.kernel.org/show_bug.cgi?id=6710)

We can limit "dev->max_sectors" to workaround the TORiSAN problem.
But I don't know whether "dev->max_sectors" also works for SG_IO?
If no, some user space application, unaware of the problem,
might send a "correct" READ that locks the drive completely.

--
albert