Comment # 30 on bug 1018741 from Gary Ching-Pang Lin

(In reply to lists dev from comment #28)
> > startup.nsh is for UEFI shell, and it only works when BDS boots UEFI shell.
> ...
> > For the one-time boot, enter the "Boot Maintenance Manager" and choose "Boot
> > From File" to find the specific efi image. To create a permanent boot
> > option, choose "Boot Options" -> "Add Boot Option". You can change the boot
> > order with "Boot Options" -> "Change Boot Order". But it seems your guest
> > has problem to save NvVars correctly, I'm not sure if the boot option will
> > be saved.
> 
> 
> In Dom0, I can (still) easily set 'EFI Shell' to Boot Order == 0000.
> 
> With startup.nsh in place, on boot it does -- as you explain -- fall through
> to startup.nsh after ~4 sec delay.  Works well if needed.
> 
> In the Guest, I am not able to get the boot option to stick.
> 
> Is it possible, from within chroot, to write a correct set of NvVars
> directly, and get the guest-boot process to use them?
>

AFAIK, there is no such tool.

> I can certainly use efibootmgr to write to file, but am not clear if that's
> sufficient, or what the recommended options should be.

If the guest can boot to OS, efibootmgr is recommended to change the boot
options and boot order.