Finding: Promoting SeaBIOS Cloud Images to UEFI Secure Boot (Proxmox)

Discovery Legacy cloud templates often lack the partitioning and bootloader binaries required for UEFI Secure Boot. Attempting to switch such a VM to OVMF in Proxmox results in “not a bootable disk.” We discovered that a surgical promotion is possible by manipulating the block device and EFI variables from the hypervisor. The Problem Protective MBR […]