How about this as an alternative/replacement for umsdos:
1) Under dos, create a large contiguous file--obviously this is a dos file
in a dos partition.
2) Convince Linux to use this file as if it were a linux partition.
3) Do the normal linux things to it--specifically: mkfs & mkswap.
There is such a thing; it's called the loop device. It's been around
for a long time, but it's only recently been integrated into the
main-line kernel. The newest mount comands will automatically use the
loop device to attach a file to the loop device, and then mount a
filesystem using the loop device.
What's missing for this to be a complete replacement for umsdos is the
ability to do this all at the kernel level at boot time, so that you can
use a file on a MS-DOS partition, mounted through the loop device, as a
root device, so you can boot a Linux system without needing need a mini
Linux partition to use as your root.
Andries.Brouwer@cwi.nl is the most recent hacker of the loop filesystem;
he's the one that finally gotten it integrated with the mainline kernel.
(I wrote the original version a long time ago, but I pursuaded another
developer outside of the U.S. take it over, so that people could add
interesting things like DES encryption to it.) I'd suggest that you
contact him and work with him if you're interested in trying to develop
a solution for using the loop filesystem to mount the root filesystem.
There are some interesting configuration details, and some changes would
be required if you wanted LILO to work from within the root loop
filesystem, but the technical problems should all be solvable.
Regards,
- Ted