Messages in this thread | | | Date | Fri, 27 Jan 2006 17:37:48 +0100 | From | Bartlomiej Zolnierkiewicz <> | Subject | CD writing in future Linux try #2 [ was: Re: CD writing in future Linux (stirring up a hornets' nest) ] |
| |
Hi,
I'm stealing thread in hope of stopping flamewar and finally having some useful discussion.
I address this to everybody not only to Joerg:
[*] As this is my thread now discussing SG_IO on /dev/hd* vs /dev/sg* is BANNED. Please continue discussing this in the old thread. :-)
I'm sure thare are other important things that we can agree on.
If it doesn't work it will be my first and the last mail in this thread...
On 1/27/06, Joerg Schilling <schilling@fokus.fraunhofer.de> wrote: > Vojtech Pavlik <vojtech@suse.cz> wrote: > > > > The only integrative (and this useful for libscg) interface on Linux is /dev/sg* > > > > > > /dev/hd* may look nice if you only look skin-deep > > > > > > How do you e.g. like send SCSI commands to ATAPI tape drives on Linux? > > > > I see you asking this again and again, and you seem to want to hear this > > answer: "You don't." I haven't checked the code, but I guess the SG_IO > > interface isn't available there. And I don't think this is a problem, > > because a) if it was needed, it can be added trivially with minimum > > added code, b) ATAPI tapes are dead, much the way ATAPI floppies are. > > Nice to see that agree that sending SCSI via /dev/hd* is a hack with limited > benefit. > > Maybe (now that we did agree about the way to go) it makes sense to start > discussing which bugs in Linux need to be fixed in order to close e.g. > the Bugs in the Debian bug tracking system for cdrtools that are related to the > Linux kernel.
Yes, lets talk about other problems, do you have pointers bugs handy? I'm not very familiar with Debian bug tracking system and I see there more than 3 bugs for cdrtools.
> 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.
I'll take a look, it should be quite easy and I don't see a reason for this restriction.
> If we sum up the time spend on this discussoion, I really cannot > understand why this has not been fixed earlier.
Because nobody cared and flamewaring is easy in contrast to doing some real work.
> - /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.
What are the return values of SCSI_IOCTL_GET_IDLUN and SCSI_IOCTL_GET_BUS_NUMBER needed for?
Please elaborate as:
* SG_IO ioctl doesn't require lun and bus number for arguments * sg_io_hdr_t also doesn't contain/require these fields
so I simply cannot see why they are needed by kernel.
If lun and bus number are needed by cdrecord please explain why (if only for enumerating devices sorry but see [*]).
> - If sending SCSI sia ATAPI, Linux under certain unknown conditions > bastardizes the content of SCSI commands. A possible reason may be
Sorry but I can't do much about it without knowing more details.
Please provide some way to reproduce the problem ("certain unknown conditions" is not very useful).
> that it sends random data in the remainder between the actual > SCSI cdb size and the ATAPI SCSI cdb size.
It should send 0-s but I'll recheck this.
> ATAPI drives that verify SCSI cdb's for correctness fail in this > case.
Thanks, Bartlomiej - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |