Re: simple message under BIOS/CSM/LEGACY

[Pascal]

thanks for the track of the second active partition (as Ubuntu does
according to exchanges on the syslinux mailing list).
I'll try it, but I'm wondering if I'm not going to abandon GPT partitioning
in favor of DOS partitioning which remains fully operational under UEFI...

Le mer. 3 août 2022 à 20:25, Pascal Hambourg <pascal@plouf.fr.eu.org> a
écrit :

> Le 03/08/2022 à 16:11, Pascal a écrit :
> > *this is python biting its tail ;-)*
> >
> > here is what I plan to test :
> > leave the protective partition in place (1), mark it as active (2) and
> > change its first sector to zero (3).
> >
> > 1) its absence seems to be a problem (at least with qemu/ovmf),
>
> The GPT scheme is usually not recognized without a protective partition.
>
> > 2) gdisk does not activate it by default,
>
> As expected. Setting the boot flag on the protective partition is
> against the EFI specification.
>
> Also, some UEFI firmware refuse to boot in EFI mode if the protective
> partition has the boot flag set. Setting the boot flag on another (even
> empty) partition entry has given good results with both legacy and EFI
> boot.
>
> > the only point that seems contentious to me is whether a partition can
> have
> > its first sector set to zero ?
>
> In the MBR/DOS partition scheme, it should not because the first sector
> is reserved for the MBR (but in Sun/BSD disklabel, partition 'c' starts
> at sector 0 and covers the whole drive). But Debian installation images
> for x86 are set up this way :
>
> Device Boot Start     End Sectors  Size Id Type
> sdb1   *        0 1320959 1320960  645M  0 Empty
> sdb2         4288   13343    9056  4,4M ef EFI (FAT-12/16/32)
>
>
> > does the BIOS check this kind of thing ?
>
> Not in my experience, but I haven't used the Debian installer with all
> existing firmware.
>
>