Messages in this thread | | | Date | Sun, 31 Jul 2005 15:01:57 +0100 | From | Christoph Hellwig <> | Subject | Re: SCSI DVD-RAM partitions |
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On Tue, Jul 12, 2005 at 10:23:17AM +0200, Thomas Heinz wrote: > Hi Christoph > > You wrote: > >While adding support for partitions on sr is trivial it has a huge > >drawback: it's chaning the dev_t space by using up device numbers > >for partitions, so /dev/sr0 ff will have different device numbers > >with that change applied. I have an old patch that's supposed to > >enable support for partitioned scsi removable devices at > >http://rechner.lst.de/~hch/hacks/sr-parts.diff, I'm not sure it > >actually ever worked (but you should get the basic idea from it) > > Ok, thanks for your valuable input. In fact, I thought about making > the device available both as /dev/srX and /dev/sdX at the same time > in order to support partitions. In my case it would even suffice to > make it available as /dev/sdX instead of /dev/srX.
That doesn't make sense because sd is a very different driver from sd. Besides that aliasing different dev_ts to the same underlying blockdevice can't work, it's cause all sorts of aliasing problems.
> Since I have no expert knowledge about this topic, I would be > interested in the general attitude towards "partitions on SCSI > DVD-RAM media / SCSI removable devices": > - Are partitions intentionally not supported? If so, why?
Historical coincidence.
> - Does it usually work but not with my specific DVD-RAM model? > If so, why? > - Do you think that this should be fixed?
There's no nice way to fix it unfortunately.
> Please note that personally, I can live with the "losetup hack" > since it is easy enough to write a program which encapsulates > partition mounting. However, there might be people which would > prefer plugging in a (possibly pre-)partitioned medium and > having the partitions work out of the box in the expected way.
It would probably be better to use device-mapper than the loop device. I think there's already userland partition parsing code for dm, and having a simple command line tool to do that, and maybe even automatically run through udev and creating /dev/sr<num>p<partition> devices would be very nice to have as an almost invisible workaround.
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