When Fedora is installed on an UEFI system, existing boot loaders (for example, the code found in the Master Boot Record) are not overwritten. Therefore, Fedora has considerably less control over the boot process. In some cases, systems cannot dual-boot between Fedora and other operating systems. Even if Fedora is selected manually in the firmware boot loader selection dialog (choose a temporary startup device in Figure 2.1, “Firmware activation instructions”), the other operating system is started. This is not a problem with UEFI Secure Boot; on the affected systems, it also happens with Secure Boot disabled.

UEFI Secure Boot (and its Microsoft variant) require secure firmware updates. Typically, this is implemented by writing a signed update to a staging area, where the firmware picks it up during the next boot, verifies it, and then proceeds to overwrite the actual firmware. However, this process is still far from foolproof and firmware updates still can make devices unusable, requiring a firmware replacement.