On Thu, 30 Oct 2003, Ljubomir Bozic Jr. wrote:

On Monday 27 October 2003 18:43, Peter Osterlund wrote:

...

- Removed unnecessary FLUSH_CACHE command from ide-cd.c. It is not necessary, and some broken LG CD-ROM units get damaged by the FLUSH_CACHE command. (Apparently they interpret the command as a firmware upgrade command.)

I would like to ask you if you could explain FLUSH_CACHE a little bit more. What exactly is the FLUSH_CACHE function and for what purpose was it used by You/Mandrake? Why is it not necessary to have it any more?

The purpose of the FLUSH_CACHE command is to make sure all data has been written to the disc before the user has a chance to eject the disc. This is necessary when writing to the disc but doesn't do anything useful if the disc is only being read. The old code issued FLUSH_CACHE commands from two places. It did it in the pktcdvd module when closing the device if it was opened for writing. It also did it from the generic cdrom code (ide-cd.c), but this generic code did the flush even if the device was only opened for reading. The new code simply drops the FLUSH_CACHE command from ide-cd.c, which is ok because the flush in pktcdvd is still present. -- Peter Osterlund - petero2@telia.com http://w1.894.telia.com/~u89404340

On Fri, 31 Oct 2003, Ljubomir Bozic Jr. wrote:

On Thursday 30 October 2003 19:26, Peter Osterlund wrote:

...

The new code simply drops the FLUSH_CACHE command from ide-cd.c, which is ok because the flush in pktcdvd is still present.

Does it mean that it is still possible to fry firmware on a faulty LG drive by using pktcdvd?

Only if you load the pktcdvd module, run pktsetup for the LG drive and open the drive for writing. I don't think this would even be possible on a CD-ROM unit. -- Peter Osterlund - petero2@telia.com http://w1.894.telia.com/~u89404340

On Friday 31 October 2003 11:45, Peter Osterlund wrote:

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Only if you load the pktcdvd module, run pktsetup for the LG drive and open the drive for writing. I don't think this would even be possible on a CD-ROM unit.

So, for CD-RW's that are affected, and if pktcdvd is used, the only hope is new firmware from LG?

I think CD-RWs are not affected. As writers they interpret the FLUSH command the right way (I guess).

Jens Axboe wrote that he observed same problem on some Compaq machines year or two ago. Do you know the reason why it happend now on a massive number of LG drives and not before or on some other distro than Mandrake?

As I see it it is just a bad luck for Mandrake and LG should at least fix their firmware if not apologize for all the inconvenience.

Thanks!

Best regards, Ljubomir Bozic Jr.

Regards, Ingo