I have a case where a linux distribution defaults to creating GPT disks, on BIOS based hardware. Subsequent re-partitioning by Windows Vista or 7 causes the GPT structures to remain untouched and intact, with only LBA 0 modified such that a valid legacy MBR is created. This condition is also reproducible by util-linux fdisk.
When a disk contains a valid legacy MBR *and* an otherwise valid GPT, which does GRUB2 honor? >From UEFI 2.3.1 Errata A. 5.3.2 says:If a GPT formatted disk is reformatted to >the legacy MBR format by legacy software, the last logical block might not be >overwritten and might still contain a stale GPT. If GPT-cognizant software >then accesses the disk and honors the stale GPT, it will misinterpret the >contents of the disk. Software may detect this scenario if the legacy MBR >contains valid partitions rather than a protective MBR (see Section 5.2.1). So it seems clear that the valid legacy MBR should be honored, and the GPT ignored. Chris Murphy _______________________________________________ Grub-devel mailing list [email protected] https://lists.gnu.org/mailman/listinfo/grub-devel
