[syslinux] Stumped by extlinux After OS Upgrade

[John.Florian at dart.biz]

Hello fellow syslinux/extlinux users!  Please forgive the long post, but I 
believe my problem warrants the background info to understand the issue.

I've developed a specialized spin of Fedora that runs off CompactFlash. 
The spin is actually produced by the livecd-tools package and is then 
transferred to the CF card -- which has been formatted with ext3 -- using 
livecd-tools' livecd-iso-to-disk.  I have hundreds of embedded systems 
running this spin.  Every now and then we need to upgrade these systems 
and needless to say swapping CF cards is labor expensive.  Thus I 
developed an in-place upgrade which essentially downloads a new squashfs 
image and syslinux directory, both of which are obtained from a newer 
spin.  These downloads do not overwrite those of the running system; they 
get a name suffix of ".new".  Then a special initrd is booted into which 
looks for the new stuff and puts them in place after renaming the 
originals with an ".old" suffix.  Another reboot occurs and the new spin 
is then running.  Currently I'm trying to effect an upgrade that will take 
these systems from a Fedora 10 base to Fedora 13.

Now the fun part and my problem.  Before shipping CF cards out with F10 on 
them, I went through rigorous functional testing and one step was to 
verify that future upgrades would be successful as best that I could. 
Since F10 was the latest Fedora at the time it was only a pseudo-test that 
tried to upgrade the F10 spin to an alternate, distinguishable F10 spin. I 
made that work, but found it necessary to run "extlinux --update 
/sysroot/syslinux" after swapping in the replacement squashfs image and 
syslinux directory.  I don't recall exactly why it was necessary, but 
suffice it to say it solved the problem and I could reboot the system and 
be running the alternate F10 image.

Now I'm doing it for real but instead of that alternate F10 spin, the 
upgrade would bring F13 into place.  Everything works smoothly -- the 
extlinux update runs without error and has the expected message indicating 
"/sysroot/syslinux is device /dev/sda1" -- right up until that final 
reboot which should take us into F13.  What happens?  Well, I get a 
"boot:" prompt for a second or two and then it disappears and then repeats 
endlessly.

I've tried a variety of things and have learned much, but not enough to 
understand the problem and have become rather perplexed.  Inspecting the 
CF card on my desktop system, I find what I'd expect.  I can make notes of 
kernel parameters as found in extlinux.conf, return the card to the 
device, power up and provide those same parameters at the "boot:" prompt 
and the device will boot into F13 just fine.  Once there I can manually 
run "extlinux --update /mnt/live/syslinux" and the system will reboot fine 
thereafter w/o intervention.  (The path changes, but is effectively the 
same directory, it's just mounted differently between the initrd and the 
regular running system.)  I have also manually run the "extlinux --update" 
from my desktop system (also F13) and found that also will "repair" the CF 
card to good working order.

My hunch is that either extlinux cannot find it's conf file or maybe the 
path difference between initrd and regular somehow does matter.  Neither 
seems likely though since my F10-F10 test upgrade worked.  That makes me 
wonder about using "extlinux --update" from F10 on a syslinux directory 
that was already populated by a F13 system and some compatibility issue. 
I've noticed that my manually run "extlinux --update" makes extlinux.sys 
grow a bit too as if the run from the initrd may have left something out, 
but I really know nothing about that file (yet).  Lastly, there's been a 
change in the "root=" kernel parameter between F10 and F13 that maybe is 
at play here.  In F10, this read as "root=UUID=blablabla" but now reads as 
"root=live:UUID=blablabla".  When I provide the kernel parameters manually 
at the "boot:" prompt I must use the F13 form for a fully successful boot, 
but even if I use the F10 format it get's much further than on its own -- 
it fails around the pivot_root point.  Maybe the "live" bit is confusing 
the syslinux package in the initrd of F10?

Any ideas would be greatly appreciated!

--
John Florian