Re: CD-RW as a normal hard disk?

Rogier Wolff (R.E.Wolff@BitWizard.nl)
Fri, 13 Nov 1998 10:41:06 +0100 (MET)

David Woodhouse wrote:
>
> mandree@dosis.uni-dortmund.de said:
> > Please note that CD-RW don't have as many read/write cycles per block
> > as hard disks have, you will probably very soon lose your
> > administration blocks on your CD - which is basically why you don't
> > use ext2/fat/whatever is normally used on hard disks. CD-RW is
> > probably not meant as a hard drive replacement anyways.
>
> Nonetheless, it should be possible, shouldn't it?
>
> Does that the Linux SCSI code has to be tricked into presenting it as a DASD,
> rather than as a CD-ROM? Or can it just be done with 'mkfs.ext2 /dev/sr0'?

mke2fs crashes when it first tries to write the superblock, because there
is a "if (open_mode & FLAGS_WRITE) return -EROFS;" in sr_open.

And I just found:
case WRITE:
SCpnt = end_scsi_request(SCpnt, 0, SCpnt->request.nr_sectors);
goto repeat;
break;
Which is the "error abort" in case of a write.

For my DVD-RAM, I added:
if ((vendor == MY_VENDOR) &&
(device == MY_DEVICE) &&
(devtype == CDROM)) devtype = HARDDISK;

to SCSI.c , but this should be extended to use a table-based
"correction table".

Still, the question is why do we still have a "sr" driver? It seems
that harddisks can be "changed" now, and have doorlock support. My
guess is that only the audio ioctls are unique to cdroms.

The sr driver seems to have a lot in common with the "sd" driver.
But also a lot of stuff that looks like bugfixes are in one but
not the other.

Roger.

-- 
| Most people would die sooner than think....  |    R.E.Wolff@BitWizard.nl 
| in fact, most do.  -- Bertrand Russsell      |     phone: +31-15-2137555 
We write Linux device drivers for any device you may have! fax: ..-2138217


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