Re: CD writing in future Linux (stirring up a hornets' nest)

From: James Courtier-Dutton
Date: Fri Jan 27 2006 - 11:42:35 EST


Joerg Schilling wrote:
This are the three most important Linux kernel bugs:

- ide-scsi does not do DMA if the DMAsize is not a multiple of 512
A person who knows internal Linux structures shoule be able
to fix this (and allow any multiple of 4) in less than one hour.
If we sum up the time spend on this discussoion, I really cannot
understand why this has not been fixed earlier.

- /dev/hd* artificially prevents the ioctls SCSI_IOCTL_GET_IDLUN
SCSI_IOCTL_GET_BUS_NUMBER from returning useful values.
As long as this bug is present, there is no way to see SG_IO via /dev/hd* as integral part of the Linux SCSI transport concept.

- If sending SCSI sia ATAPI, Linux under certain unknown conditions
bastardizes the content of SCSI commands. A possible reason may be
that it sends random data in the remainder between the actual SCSI cdb size and the ATAPI SCSI cdb size.

ATAPI drives that verify SCSI cdb's for correctness fail in this
case.

Jörg
Would you be able to add the appropriate kernel bugzilla numbers?

I think it might also be useful to make a list of all the SCSI commands that cdrecord uses. Including all the vendor specific ones. One could then verify that the Linux kernel is passing them onto the device correctly.

James


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