Peter Stuge wrote:
The MBR is irrelevant in the above scenario, it is never read.
..
The payload directly reads the filesystem from disk, no boot sector is used.
To clarify, I mean code here. No code is read/loaded/used from MBR.
The partition table is read, but I expect that GRUB2 supports both GPT and MBR partition tables, so MBR is not a requirement, and can likely be changed at will, without needing to modify coreboot or GRUB2 in boot flash, as long as the GRUB2 config file correctly reflects system configuration.
//Peter