I am having trouble figuring out how to have grub installed on a floppy in a way that it automatically boots a modified Ubuntu 12.04 CD on startup. I will settle for knowing some commands at the grub prompt if automation is asking for the impossible.
The CD is bootable, but the system this is made for doesn't have a BIOS option to boot from CD (or USB), it can only boot from floppy or hard drive.
This is a system located remotely, and I would like to have something where I can tell the owner if there are problems: insert floppy and CD and reboot. The modifications to the CDs are such that openssh-server is installed, my public ssh key in /root/.ssh/authorized_keys2, ssh is listening on an additional port number as those < 1024 are blocked by the local provider and the system retrieves a page on my server (so I can find the IP address to connect to for remote maintenance). The CD works fine when testing in a VirtualMachine. There is a keyboard and monitor and I can ask the owner to type in a few commands.
I first looked at using grub2 but there are many incorrect how-to about them and the command-line options for grub2 seem to have been changed a lot of times (
--overlay, often mentioned, are no longer there).
There is a bug report about grub2 output not fitting on floppy and that was closed recently. So I build grub2 from the repository (version 2.0) including the required new version of xorriso. The result of
grub-mkrescue --compress=xz -o grub-rescue.vfd
is a 4.4Mb Image, which of course does not fit on a floppy at all, so I dropped that as a viable path to explore.
I have tried a grub legacy on floppy (0.97), but cannot use
find from the grub prompt to find anything on the CD, nor use something
chainloader (hd1). The grub (0.9x) manual has nothing to say about booting an iso image.
I rather not install something on the hard drive and go the boot route FD -> HD -> CD as this whole setup is needed in the first place if the hard drive has problems.