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

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At 2013-11-12 03:15:50, "Andrey Borzenkov" <address@hidden> wrote:
>В Mon, 11 Nov 2013 18:58:20 +0100
>Jacek Konieczny <address@hidden> пишет:
>
>> 
>> 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.
>
>Do you mean - in addition to EFI boot image? Because EFI requires ESP
>in "no emulation" mode to boot.
>
>>                                                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.
>> 
>
>Why "msdos"? El-Torito CD does not have standard DOS label, so it would
>be wrong name. And if you place whole image of partitioned disk there,
>it becomes nested partition (dos label in El-Torito "partition").
>
>Something like (cd,eltorito0,msdos1) probably.
>
>> Is it a bug? Am I doing something wrong?
>> 
>
>No. As it stands currently grub does not expose El-Torito image as 
>partition of CD media. It is completely invisible unless you use hybrid
>CD which contains other partition labels referring to it.
>
>> 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.
>
>But you need to place image on CD either way. Are you using this image
>for anything else, like directly booting on non-EFI?
>
>>                                  GRUB should be able to see the El-Torito
>> contents, shouldn't it?
>> 
>
>So far there was not any use case. But yes, technically EFI does expose
>it as "partition" so grub probably should too.
>
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