A few days ago, I installed the Windows 10 “April update”, and it broke my GRUB installation. What happened? My primary disk has an MBR partition table. (Apparently, booting from GPT requires using UEFI, which exposes a whole new exciting set of firmware bugs.) GRUB was installed in a small ext2 partition (primary partition #3), while primary partitions #1 and #2 were used by Windows 10. Installing the April update created another primary partition and moved my ext2 partition to slot #4 s...
