Subject: Re: Disklabel oddity
To: Wolfgang Solfrank <>
From: Ken Hornstein <>
List: tech-kern
Date: 04/19/1996 11:13:02
>> So, I've been looking at adding multisession support to the SCSI cd
>> driver.  Doesn't look too hard - looks like the right thing to do is
>> read the TOC, generate a synthetic disklabel using the information from
>> the TOC, and then you can just access the the different sessions as different
>> partitions.
>But that's not what multisession CDs are about.
>On multisession CDs, you should only read the directory tree of the last
>session. This one will have pointers to files in previous sessions, too.

Hmmm, this is totally different that what I've been lead to believe, but
I have no doubt that you're more knowledgable than me.  But I have seen
cases where multiple sessions get mounted as different volumes on a
Macintosh desktop, but that's what is NOT known as multi-volume, right? :-)

>If you want to determine, whether some track is ISO-9660, or some other format,
>that's only distinguished by its contents. Like the difference between say
>tar and cpio format.

Yes, that's what I meant.

Hmmm, the more I think about it, the more I realize that using disklabel
perhaps isn't the right thing to do.  The block numbers in the ISO filesystem
are probably absolute, and shouldn't be offset-corrected by the disklabel

It almost sounds like it makes more sense to add functionality to
mount_cd9660 so you could specifiy a session number.  You could then have
it read the disklabel, figure out the start of the ISO filesystem, and pass
that to the mount system call.  What do people think of that idea?