Also on Debian based systems [LWN.net]

Also on Debian based systems

Posted Jul 31, 2020 21:23 UTC (Fri) by anselm (subscriber, #2796)
In reply to: Also on Debian based systems by kreijack
Parent article: Grub2 updates for Red Hat systems are making some unbootable

In fact both GPT and MBR partition can co-exist together (and say the same thing or different thing ! more often the latter).

Theoretically, GPT-partitioned disks have a fake MBR with one huge untouchable “partition” that covers all the space within the GPT partitions. (This only gets you so far if your disk is bigger than MBR will support.)

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Also on Debian based systems

Posted Aug 2, 2020 6:05 UTC (Sun) by kreijack (guest, #43513) [Link]

> Theoretically, GPT-partitioned disks have a fake MBR with one huge untouchable “partition” that covers all the space within the GPT
> partitions. (This only gets you so far if your disk is bigger than MBR will support.)

Correct.

To complete the answer, I have to point out that below of the "MBR" label there are two kind if information:
- the partition table
- the boot loader

Both are stored in the first sector. Grub-install change only the latter. So in any case grub-installer can't change nor damage the GPT table. However installing a MBR boot loader, could start the bios in legacy mode (and not uefi one).