From: gram@aim1.aztec.co.za (Graham Wheeler)
Newsgroups: comp.unix.sysv386
Subject: CD-ROMs/New file systems (summary)
Date: 23 Jul 92 15:34:50 GMT
Organization: Aztec Information Management

A couple of weeks ago I posted queries about using a CD-ROM drive under 
Dell SVR4. Our problem was that we could dd the info in with a raw device,
but we could not mount the disc. I posted an initial query about this, and
then a second query about how easy it would be to create the file system
support. The following is a summary of the responses I received.

>From: jack@admin.mport.COM (Jack Craig)

given that microport and dell get their src from the same usl and that 
we got no cdrom filesystem either, the truth is there isnt one yet. 
i hope to start soon.

in the meantime, the portable filesystem(pfs) from young minds(714-335-1350)
has been used by several of our customers. some with autochanger cdroms.
note a limit of 8 units in the stock release. beware as we(i) fixed this for
microports os.

email me direct for more specifics.

jack...
=============================================================================
 Jack Craig               Aptos, California, 95003  
 Software Horizons,Inc.   408-684-1375    uunet!sco.com!blznrzn!jack    SVR32
 Microport                800-FOR-UNIX    uunet!mport.com!jack          SVR40
=============================================================================

The next message comes from a contact at Dell, whose name I have removed
as he is effectively our sole `technical support' from Dell (we don't use
Dell hardware...), and I would hate him to either get into trouble over this
or get flooded with questions from all the other non-supported Dell UNIX
users (wouldn't it be nice if Dell took their UNIX as seriously as most of
us do?).

> yaturner@picard.agames.com (D'arc Angel) writes:
> 
> >I called Dell and asked them about this, I was told that you could mount
> >the CD and access the "native" file system (the ISO format itself) but
> >that there was no unix file system "overlay" for CD's. Maybe in the new
> >release, I'm told that it's RSN.....
> 
> I don't understand how you can mount a device if there is no file system
> type. We tried doing mounts with every file system type that is listed in
> /etc/conf/mfsys.d, and they all failed. We have not been able to do anything
> better than a `dd' (which isn't much use 8-( ).

You can only access the device in raw mode.  You can't mount it becuase
there is no filesystem support.  There is a device driver for CD-ROM's, but
no filesystem support.  There will not be any filesystem support in the
next release initially, although we have been looking at some possibilities
for the filesystem support.  No set plans for it yet, though.
==========================================================================
From: steve@nuchat.sccsi.com (Steve Nuchia)

I attended the V.4 internals tutorial at the recent Usenix and
asked specifically whether there was enough information available,
in any form, without a source license to write file systems.

The answer was no.
==========================================================================
From: Mitchell.Erblich@EBay.Sun.COM (Mitchell Erblich)

I am not sure, but I think the HSFS (High Sierra File System) is ISO9660 compatible.
Ask Dell if it is on your release.  It is the standard CD-ROM FS on SVR4 OS.

Mitchell Erblich
Software Engineer
Sun Microsystems
=========================================================================
Mitchell is quite correct about the compatibility, but it seems that support
for this file system type was one of the things that was *not* incorporated
into SVR4 from SunOS.
=========================================================================
From: Peter Wemm <Peter-Wemm@zeus.dialix.oz.au>

In comp.unix.internals you write:

>We have some CD Roms that we would like to read under Dell SVR4. Unfortunately,
>although Dell provide a device driver to access SCSI CD Rom drives, they don't
>provide an ISO9660 file system type. I have a copy of recently posted (on
>alt.sources) BSD386  source code for this.

Join the club... :-)

>* how compatible is a BSD VFS type with an SVR4 one? In other words, just
>	how resuseable is the BSD386 code under SVR4?

They are remotly similar, but that's it..  If you see the vfsops and vnops
tables in the BSD code..  Well the great big list of functions there are
ALL DIFFERENT in SVR4.  I ahve not been able to get any real documentation
on these, but if you find any **please** let me know!

>* what are the requirements of a VFS device? Are there any unusual entry 
>	points? Are these STREAMS devices, or conventional?

They are neither..  And they have real funny entry points..

>* is there any documentation available on how to go about this?

Easy:  Spent US$100,000, and buy a source license!  That's the usual answer
I get when I ask for DOCS.

>* is there any existing PD SVR4 code for this? (saves me a lot of work!)

No..  Not that I have seen..
==========================================================================
>From: terry@thisbe.npd.Novell.COM (Terry Lambert)

|> * how compatible is a BSD VFS type with an SVR4 one? In other words, just
|> 	how resuseable is the BSD386 code under SVR4?

	Not very.  The top layer (VFS-to-FS) is fairly explicit; the bottom
(FS-to-memory-management) isn't.

|> 
|> * what are the requirements of a VFS device? Are there any unusual entry 
|> 	points? Are these STREAMS devices, or conventional?

The entry points are documented in the files /usr/include/sys/vnode.h and
/usr/include/sys/vfs.h.  They are not devices, per se, they are a set of entry
points which are added to the VFS switch.  They are formulated as "Driver.o"
files on SVR4 to enable idbuild to deal with "Y"/"N" on whether to include them.

Warning:  Dell UNIX uses the table offset into the VFS switch table to identify
the file system, rather than the string name (as documented by AT&T).  This
means that you won't be able to use existing file systems that occur later in
the collating sequence (ie: lofs would come before ufs, then blow up any ufs
file system).  Fix this by editing /etc/conf/cf.d/fsconf.c in the middle of
idbuild (unless you are damn fast, this will require putting a "read x" before it
is used to build fsconf.o 8-).

|> * is there any documentation available on how to go about this?
AT&T has some documentation that you can get if you are a source license.  IBM
has a manual, "Writeng a Device Driver for AIX Version 3.2" that comes with a
disk with a demonstration VFS for AIX.  Pub number is GG24-3629-01, and it costs
extra (doen't come with the standard manual set).

|> * is there any existing PD SVR4 code for this? (saves me a lot of work!)

Yes, but I'm currently beta-ing it, and won't release it for a while...

					Terry Lambert
					terry_lambert@gateway.novell.com
					terry@icarus.weber.edu
=============================================================================
Well, it seems like Terry is going to save the day. BTW Terry, I tried mailing
you unsuccessfully. If you have any need for additional testers, we are quite
prepared to do so.
=============================================================================

-- 
Graham Wheeler                     | "That which is weak conquers the strong,
Software Systems Engineer/Student  | that which is soft conquers the hard."
Aztec Information Management/UCT   | 		Lao Tzu - Tao Te Ching Ch. 78
gram@aim1.aztec.co.za / gram@cs.uct.ac.za