Comment 3 for bug 1853906

Machines managed by MAAS are always configured to boot off of the network. When an image is deployed MAAS sends grub, which was loaded over the network, a configuration file[1] which searches for the local boot loader to chain boot to. As per 13.3.1.3 of the UEFI spec[2] MAAS first tries the default location for a local boot loader, \EFI\BOOT\BOOTX64.EFI. If that is not found or fails to load a number of known vendor directories are searched and attempted. If everything fails GRUB exists so the firmware tries the next boot device.

If I keep a close eye on the UEFI machine booting I can see that \EFI\BOOT\BOOTX64.EFI is being loaded but fails to chain load \EFI\BOOT\GRUBX64.EFI. On UEFI QEMU as well as our CI machines GRUB continues, finds /EFI/ubuntu/shimx64.efi and booting succeeds.

Do you have secure boot enabled? If so can you try deploying with it disabled? It may be causing the boot process to lock when BOOTX64.EFI fails to load.

I'm adding GRUB and shim as \EFI\BOOT\BOOTX64.EFI should chain load to the locally installed GRUB. I'm also not sure why GRUB isn't trying the other alternatives its given.

[1] https://git.launchpad.net/maas/tree/src/provisioningserver/templates/uefi/config.local.amd64.template
[2] https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_final.pdf