Re: UEFI/"BIOS" booting

[Pascal Hambourg <pascal@plouf.fr.eu.org>]

Le 16/05/2018 à 00:10, Pascal Hambourg a écrit :
> Le 15/05/2018 à 08:51, Thomas Schmitt a écrit :
> > Summary:
> > - Boot flag on MBR partition of type 0xEE is bad on several EFI
> >    implementations.
> > - No MBR partition with boot flag is bad on some very few BIOS
> >    implementations.
>
> Not so few in my experience.
>
> > - Compromise is to set the boot flag on a dummy partition of type 0x00.
> >    This is barely UEFI-compliant because the specs say that a 
> > partition of
> >    type 0x00 shall be regarded as non-existent.
>
> I never thought about this. It may be a workaround with my old UEFI 
> motherboard. Thanks for the tip, I will try it and report.

The trick indeed worked with my old motherboard ! Good to know, thanks.

However there are some caveats :
- I had to use the old fdisk version from Wheezy because newer versions 
and other partition editors would not allow to set the boot flag on an 
empty partition entry.
- parted silently erased the flag when I used it to edit the GPT table. 
I expected it, because parted had already reset a hybrid MBR I had set 
up with gdisk to a standard protective MBR.