Subject: Re: mkhybrid and/or vnconfig problem
To: None <port-i386@netbsd.org>
From: None <Federico_Lupi@mail.datasys.it>
List: port-i386
Date: 05/30/2001 10:19:54
Richard Rauch <rauch@eecs.ku.edu> wrote:
> A couple of comments:
>
>  * I have not needed to specify the 512/556/1/1 parameter to vnconfig.
>    Can you elaborate on a situation where this is required?

It's not always needed but on some occasions I found that you can't
read an image correctly if you don't specify the parameters.  When I
create NetBSD CDs, I create an image on the hard disk, mount it and
check every file (MD5 and gzip integrity) with a shell script.  I
noticed that sometimes the script would report a corrupted .gz file
but after writing the image to the CD the file was OK.  If you
specify the sizes to vnconfig you don't get the error.
Some time ago you could reproduce this creating an image of only
xsrc.tgz.  I'm not sure now...
See:
     http://mail-index.netbsd.org/netbsd-help/1999/11/12/0007.html

>                                                              No mention
>    of needing this is made on
>
>      http://www.netbsd.org/Documentation/bootcd.html#netbsd_mountimage
>
>  * You point to the URL
>    http://www.mclink.it/personal/MG2508/nbsdeng/chap-misc.html#AEN4052
>    in your message.  In talking about CD-ROM file systems, the page
>    says that a CD that is made with RR or Joliet extensions cannot
>    be shared.

It says that if you use _only_ RR or _only_ Joliet the CD will not be
readable an all systems.

>
>    In fact, I have made a sharable CD on which I have asked mkisofs
>    to use Rock Ridge & Joliet extensions (both), and on which I have
>    relaxed numerous restrictions in order to make the CD filesystem
>    behave more like a normal BSD/UNIX filesystem.

Mkhybrid is mentioned in the guide (now mkhybrid has been merged with
mkisofs, IIRC.)  Maybe it's not clearly explained that it's possible to
create sharable CDs with both RR and Joliet; I'll fix this and add an
example to the guide.

> If there are reasons why the NetBSD Guide says the things that it does,
> perhaps the author(s) of those sections could clarify the pages.  E.g.,
> when do you need to explicitly pass a geometry to vnconfig?  Why is it
> necessary (and why does it work for some of us without specifying the
> geometry)?

I wrote those pages :-)  I think that explaining this sort of
details is better left to the man pages, also because I don' know
_why_ and _if_ the geometry is always required.  I found that
sometimes it is required: I have received e-mails from users stating
that the "Unexpected end of file" error from gzip went away when
they added the geometry to vnconfig.  If someone knows why this
happens I'll be happy to add the technical reason to the guide
(although I don't know why a new NetBSD user would care about
this.)

I don't know why it works for some.  As I said, I use a script to check
the integrity (if possible) of every file on every CD image that I create
before writing the image to the CD; before I started doing this it worked
for me too :-)

If you browse the mailing lists you will find this problem mentioned
by other users.  Eg.
     http://mail-index.netbsd.org/port-i386/2000/01/17/0010.html

>
>
>   "I probably don't know what I'm talking about." --rauch@eecs.ukans.edu
>

Regards,

Federico