GRUB doesn't recognize partitions on El-Torito image during EFI boot from CD

[Jacek Konieczny]

Hi,

I have a system as a disk image. It can be booted directly from an USB
stick both via legacy BIOS and EFI. I wanted the same image to be usable
on a CD.

For EFI boot it should be straightforward – use the disk image as
a hard-disk-emulation El-Torito EFI boot image. I have done that with
other EFI boot loaders and it worked right.

With GRUB there is a problem – it is unable to find the boot partition.
In rescue mode I can see only:

(hd0) (cd0)

however, I would expect too see (hd0,msdos1) too – with the first
partition of the El-Torito image.

Is it a bug? Am I doing something wrong?

I made a workaround by using GRUB loopback in the embedded config for
the EFI loader:

echo "starting grub"
search.fs_uuid 8101-917C root
set prefix=($root)/grub
configfile $prefix/go_normal.cfg
echo "boot partition not found falling back to loopback device"
search.fs_uuid 2013-11-11-18-32-41-96 cd
loopback loop ($cd)/pld-nr-32.img
set root=(loop,msdos1)
set prefix=($root)/grub

It works, but I don't like this. GRUB should be able to see the El-Torito
contents, shouldn't it?

Greets,
        Jacek