RE: Cannot boot from dual bios/uefi boot CD

[John Frankish]

> > > At which point I have to remind you that I never told you to use 
> > >--modules in the first place :) You somehow insist on it, for reasons I do 
> > >not understand.
> > 
> > The reason is that, if I don't do this, mkrescue writes 4mb of modules to 
> > /boot/grub/{i386-pc, x86_64-efi},
> > most of which are not required.
>
>      --install-modules=MODULES   install only MODULES and their dependencies
>                              [default=all]

We're saying the same thing - but the problem with this is that it only works 
if the same modules exist for i386-pc and x86_64-efi. Since efi_gop does not 
exist for i386-pc, this approach does not work for me :)

> > 
> > If I manually edit the iso to remove the modules that are not required, 
> > then the iso refuses to boot complaining that
> > the modules I removed are missing (even though they are not required to 
> > boot the cd).
> >
> Yes, I have reproduced it now. The reason is, grub-mkrescue adds commands to 
> load all partition drivers to embedded
> config and if some of them (or may be the last one) is missing it sets error 
> indication.
> Later grub misinterprets this error indication when loading normal module; 
> loading it manually succeeds
> (insmod normal; normal). If I add code to reset error indication before 
> trying to load normal it works.
> 
> So it still works for your purposes, albeit with manual workaround :)

Indeed - but I could hardly make it available to others like this :)
 
> > What I am trying to do is make an iso that, when burned to cd, will boot in 
> > legacy-bios and uefi mode to a console prompt.
> > In the case of legacy-bios, this is easy. In the case of uefi, I need to 
> > load gop_efi and unicode fonts in order to have a
> > display at the console prompt.
>
> This works for me also without gop_efi and unicode. I'm on QEMU with OVMF, so 
> may be it makes difference, could be that
> real hardware is different. Of course you will probably need efi_gop to avoid 
> "blind booting" but then it is far beyond "boot
> to a console prompt" :)

Real hardware is different - after blind booting completes, I'm still blind.

> > 
> > 1. Embed only the required modules for both legacy-bios and uefi to boot.
> > 
> > Or
> > 
> > 2. Copy only those modules required to boot to the iso under 
> > /boot/grub/{i386-pc, x86_64-efi}
>
> Should I repeat --install-modules yet again? :)

Please do, but see above ;)

> > 
> > This doesn't seem unreasonable :)
> > 
>
> Yes, and there is at least one bug here that needs to be fixed.
>

Will you take care of the bug report?