Re: [TCLUG:19968] Bootable Image Lilo and CDRW

[Mike Hicks <hick0088@tc.umn.edu>]

Charles Clifton Fulton wrote:
> 
> You don't want to use mkisofs on the file if you are trying to make a
> bootable CD.

This makes sense.

> Just burn the floppy image directly.

This doesn't.

From what I understand, a floppy disk image is placed in a special
location on the disc.  The system BIOS is able to read that section of
the CD and load it into memory.  If you burn the floppy image directly
to a CD, it is no longer what I would call a `true' CD.  It doesn't
follow any of the standards at all and wouldn't be recognizeable as a CD
by anything trying to read it.  You wouldn't be able to put anything
else on the CD (well, I suppose you could read it back with `dd', but
that's a suboptimal option).  Also, as it would (at most) only the boot
block of the floppy image would be read, you wouldn't be able to boot
off of it.

Now, I should point out that mkisofs is only one of several different
programs out there for making CDs.  Unfortunately, I can't name any off
the top of my head.

(/me goes and throws Google at that problem..)

There's a linux-kernel mailing list thread here:
[http://www.uwsg.iu.edu/hypermail/linux/kernel/9908.3/0765.html]

Hmm..  I'm not finding much.  There is a modified version of mkisofs
called `mkhybrid', which is mostly for creating bootable CDs for the
Macintosh.  I am wondering what the `-G' generic bootable image option
is, though. (for mkisofs and mkhybrid)

There's a patch to mkisofs at http://www.colonel-panic.com/linux/ that
was referenced in the above lkml thread, which might help for certain
things, but I'm not sure.

Again from the kernel thread, H. Peter Anvin is apparently working on a
boot loader named `lbcon'.  However, I'm not sure if it's any better or
worse than the other boot loaders out there (GRUB is good, for
instance), and he hasn't show any code that I'm aware of.


Well, that's all getting a bit complicated.  If you had a while to go
write a new bootloader, this stuff might start getting really
interesting, but that's probably only going to hurt things.

Getting back to what John said about 1.7MB recovery floppies, I wonder
if you could get one of those to work by just using dd to bring them up
to 2.88MB.  I don't really know much about filesystem layouts, so I
don't know if that would be really bad or no problem at all.  Also, with
CDs, you don't need to have much on the initial floppy image anyway. 
I'd just have a kernel and an initial ramdisk with enough intelligence
to search around for the CD and mount it as the root filesystem (which
is essentially what the LinuxCare BBC does, though it mounts a
compressed image of a filesystem that is on an iso9660 filesystem..)

-- 
 _  _  _  _ _  ___    _ _  _  ___ _ _  __   In the carpool lane to 
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[ Mike Hicks | http://umn.edu/~hick0088/ | mailto:hick0088@tc.umn.edu ]