Re: efibootmgr help

On 08/27/2015 03:58 AM, Paul Cartwright wrote: A few things happen in sequence for Linux on UEFI systems. After the system powers on, it loads and runs the UEFI firmware. The firmware initializes hardware according to a local configuration, and then searches the UEFI boot list for the first available boot device. That list is what efibootmgr lists and edits. In the system you've shown, Fedora, Ubuntu, and Windows all have their own boot loaders installed in the list. You can select a boot loader from that list (typically) by hitting the F12 key on your keyboard during the UEFI boot sequence. UEFI then loads shim.efi, which loads grub2. In your case, it is loading the grub2 binary that Ubuntu installed, which searches for a configuration file in a different location than the grub2 binary that Fedora installed. You don't see your new Fedora kernel there, because Fedora is updating a different configuration file. You might have other options, but you should have at least these two: 1) you can manually edit the Ubuntu grub.cfg file and copy the kernel sections from Fedora there and 2) you can hit F12 to choose whether you want to load Fedora or Ubuntu's grub. After UEFI loads grub2, grub2 looks for its configuration file, parses it, and gives you a menu to select which kernel to boot. grub2 then loads the kernel and initrd into RAM, and passes execution there. The initrd contains a small filesystem in which /sbin/init is run, and the "real" root filesystem is mounted. The root filesystem is pivoted so that the real root filesystem is on /, and its /sbin/init is run. You don't need to use grub2-install on UEFI systems (and rarely on BIOS systems either). It would normally build a custom grubx64.efi, but doing so would break under Secure Boot. You could: # efibootmbr -o 0002,0004,0003,0000,0001 It does, as long as you've configured UEFI to use Fedora's grub.