Edited from work by Jim Moy, thanks Jim!

There's a 256 char limit on the syslinux.cfg kernel params line. Go and do this:

$ cat /proc/cmdline

and if it looks like your module list is getting truncated, well, there's the problem. If yours looks right then you haven't hit the limit yet, so you're fine As you add more functionality to your leaf, you might hit this limit. If you want to fix it, go look for the line in /linuxrc that looks like this:

ROOTMAP="`sed 's/.*LRP=/\1/; s/ .*//1' /proc/cmdline`"

and replace it with this:

pkglist=`cat /boot/etc/lrppkgs.cfg`
ROOTMAP=`echo $pkglist | sed 's/ /,/g'`

then put all your module names in /boot/etc/lrppkgs.cfg in a simple list, one per line. Backup the root module. Actually, I'm probably going to move it to somewhere in /etc, the root module takes longer to backup :-P From then on, it ignores the LRP= value in syslinux.cfg.