El Torito booting on older machine

[Christian Jones]

I've been playing with^H^H^H^Htesting El Torito booting with a CVS 
version I checked out yesterday.  I've got it working nicely, except on 
one older Packard Bell Pentium MMX 233MHz (yeah, I'm a bit of a packrat).

That machine does seem to work with ISOLINUX (as indicated by booting 
Slackware 9.1 installation CDs).  However, I seem to have some problems 
getting it to work with grub.  For testing, I followed precisely the 
steps in the manual:

mkdir iso &&
mkdir -p iso/boot/grub &&
cp /usr/share/grub/i386-pc/stage2_eltorito iso/boot/grub &&
cp /boot/{vmlinux,System.map} iso/boot &&
mkisofs -R -b boot/grub/stage2_eltorito -no-emul-boot \
-boot-load-size 1 -boot-info-table -o grub.iso

All worked fine without warning or error.  Recorded to cd;  boots and 
works as expected on all other (read: more modern) computers I have. 
However, on this one:

grub> root
(hd31): Filesystem type unknown, using whole disk

grub> root (cd)
Error 23: Error while parsing number

grub> root (hd31)
Error 12: Invalid device requested

grub> root (<TAB>
grub> root (hd0, [backspaced over, didn't press enter]

grub> kernel (<TAB>
Error 12: Invalid device requested

grub> kernel (cd)/<TAB>
Error 23: Error while parsing number

grub> kernel (hd31)/<TAB>
Error 12: Invalid device requested

grub> kernel (hd1)/<TAB>
Error 21: Selected disk does not exist

And similar variations on that theme.  Interestingly, though other 
machines booted appropriately enough with it, there was no change after 
adding a menu.lst (presumably because grub couldn't locate root and 
therefore just went to the prompt).  Other minor changes didn't help, 
either (there have been reports of broken BIOSes needing -boot-load-size 
4, which didn't make things worse or better, and leaving -boot-load-size 
off, which implies in this case -boot-load-size 156, leaves the disc 
completely unbootable, as in stage2_eltorito doesn't even load).  Adding 
grub stage1, stage2, etc. doesn't make a difference.

As I said, I'd be willing to just strike this up to "This BIOS is broken 
and has no El Torito support"---except that it *does* boot CDs.  I was 
unable to get it to work with floppy emulation (not surprising), but it 
works with Slackware, which used:
mkisofs -R -J -V ... -hide-rr-moved -v -d -N -no-emul-boot \
-boot-load-size 4 -boot-info-table -sort isolinux/iso.sort \
-b isolinux/isolinux.bin -c isolinux/isolinux.boot -p ... -P ... -A ...
(I purposely left out the ...s).

Phew.  Any other info I can give which might help sort out the problem?
Thanks for all the work---El Torito support in grub is a wonderful addition!
CDJ