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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.


Background:

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 (--diet and --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.

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An better alternative to all in one boot floppy is probably to use BCDL. The bootable CD loader automaticaly boots the first CDROM. The problem is that its CD driver is no longer up to date, so you need to upgrade VIDE-CDD.SYS on the floppy with e.g. XCDROM.SYS taken from here.

(Only tried with a virtual machine, not with a real FDD).

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  • I tried this and this worked very well (from a virtualdisk as well, I still need to transfer the image and burn a real floppy with it). The compressed floppy image is only 15K! – Anthon Dec 2 '13 at 14:03
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Have you looked at The All In One Boot Floppy? It can boot a CD with a few menu selections.

It using Smart Boot Manager underneath so you can look at that to make something without (or with less) interaction.

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For motherboards made prior to 2002, their BIOS's will neither see nor boot from CD. Between 2002 and 2005, the BIOS can at least see the CD. If you have the newer mobo, then you can get GRUB to boot the CD. An easy way is to put GRUB4DOS on a system DOS disk and edit the MENU.LST file to create a menu. If you have an older mobo, like mine, you will need to boot Linux from the floppy to access the CD. Some of the options are TOMSRTBT (aged but can fit in an oversized disk (1.7MB), or Basic Linux (2 floppies). The best solution, which requires work, is make your own kernel and initrd from a recent distro release with only the stuff you need. You may get them small enough to fit on a standard floppy.

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