[syslinux] floppy disk emulation boot regression

[Robert Haas]

I am in the process of trying to update a bootable Linux CD that I
initally built some time ago using RedHat 7.3 and syslinux 1.x (I
believe that x = 52, but this doesn't seem to be relevant).  In order
to do this, I first built a floppy disk image and made it bootable by
running "syslinux -s" on the image; then I incorporated this image
into a CD using "mkisofs -b boot.img -c boot.cat -o cd.iso boot.img
<other contents of CD>".  It worked great.

Last week, when I repeated these steps under Fedora Core 4 (running
syslinux-3.08), the CD would not boot - instead, I got the single line
"Boot failed", and that was all.  Experimentation revealed that the
floppy image, if copied to an actual floppy disk, would still boot,
but the same image, on CD, would not.  My first thought was that my
machine might be flaky, so I tried it on another machine with the same
results.

Then I thought this might be the result of a bug fixed in the latest
version of syslinux, so I got the source RPM for 3.11 from the
syslinux web site and built it; same problem.  I then repeated the
process using the latest RPM from the 1.xx series, which turned out to
be 1.76, and the latest 2.xx RPM, 2.13.  Both of those worked as
expected.  So it appears that sometime between 2.13 and 3.08, a
regression was introduced that affects the ability to use a boot a CD
using floppy emulation with a floppy image made bootable through
"syslinux -s", although the floppy itself will boot.

I realize that I should perhaps catch up with the times and use
ISOLINUX, but wanted to change as little as possible from the previous
version of the CD, so for now I'm using 2.13. I'm not sure whether
anyone is interested in fixing this (or whether anyone else still
makes CDs that boot using floppy emulation) but thought I would pass
along what I discovered.

Thanks,

...Robert