Re: is it possible to add a new filter to detect unusable partition types

[Michael Chang]

On Wed, Dec 18, 2024 at 06:05:54PM +0100, Thomas Weißschuh wrote:
> On 2024-12-18 15:44:45+0100, Karel Zak wrote:
> > On Wed, Dec 18, 2024 at 11:12:59AM GMT, Zdenek Kabelac wrote:
> 
> [..]
> 
> > > And in the same way blkid should expose installed grub loader - currently
> > > the partition with installed grub looks 'empty' with blkid....
> > 
> > The issue I see is that boot loaders can coexist with filesystems on
> > the same device. This can lead to unexpected warnings when attempting
> > to view the contents of the device using mkfs tools.
> 
> Isn't this specifically about the grub second stage on GPT systems
> inside a dedicated partition?

Yes, GPT has no unallocated space similar to the MBR gap in the MSDOS
partition table that can be repurposed for grub second stage, therefore
a dedicated partition has to be defined and allocated. A similar scheme
is also used in PowerPC, where a dedicated firmware PReP boot partition
must be allocated for the boot code.

See Also:

https://www.gnu.org/software/grub/manual/grub/grub.html#BIOS-installation

> There should be no valid coexistence with a filesystem.
> 
> So having a probe in blkid looks reasonable to me.
> 
> Not that it helps in the specific case mentioned above, where everybody
> is using --force anyways.

That's the reason I think adding such a check in grub-install doesn't
help at all. After adding the check, I believe the tools managing the
bootloader installation will start to use wipefs or enforce --force to
grub-install to make sure no leftover can get in the way. In that sense,
it seems like unnecessary breaking change to the toolings.

Thanks,
Michael

> 
> 
> Thomas