Subject: Custom Boot CD w/o Other NetBSD Boxes
To: None <>
From: Alex Kirk <>
List: netbsd-users
Date: 12/04/2003 16:58:23
Hello All,

After two days of research and testing, I'm finally breaking down and asking the
list what's likely a very obscure question: how I can make a bootable
NetBSD/i386 CD with a custom kernel without another NetBSD box laying around.
Basically, I'm trying to make a bootable CD for a machine without a drive, so I
need to customize the kernel on said CD at least far enough to specify "config
netbsd root on ? type nfs". Of course, if anyone reading this has already done
such a thing and has an image laying around, I'd *really* appreciate a link to it.

I saw the documentation that says you can make a bootable CD with boot-big.fs,
so I went to and grabbed a copy. I'd also seen notes on the
mailing list archives stating that I should be able to, roughly:

vnconfig -c vnd0 boot-big.fs
mount /dev/vnd0a /mnt/somewhere

And from there put in the new kernel. The problem is, on the *NIX boxes I have
access to, this doesn't work.

Under Linux, I'm told I've got no ffs support (probably could fix that with a
kernel recompile, but since I'm still new on the Linux way to do that, it'd be a
last resort). Under OpenBSD, this is what happens:

bash-2.04# vnconfig -c svnd0 boot-big.fs
bash-2.04# mount_ffs /dev/svnd0a /mnt
mount_ffs: /dev/svnd0c on /mnt: Inappropriate file type or format

What *really* killed me is the result when I dusted off my NetBSD/Dreamcast
system and tried it there:

root@dreamcast:/home/alex# vnconfig -c vnd0 boot-big.fs
root@dreamcast:/home/alex# mount /dev/vnd0a /mnt
mount_ffs: /dev/vnd0a on /mnt: incorrect super block

As best I can figure it, I won't be able to mount this image unless I've got a
NetBSD/i386 box somewhere. Hopefully someone here can either correct me, or
provide me with temprorary access long enough to do this.

All of this, of course, also presupposes that I had a clue on how to
cross-compile a NetBSD/i386 kernel off of NetBSD/Dreamcast or OpenBSD/i386.
Pointers there would also be greatly appreciated. :-)

Thanks in advance for your help.

Alex Kirk