Any reason to not just make that a semi-official image ?
…probably restricted to the edge channel if we do not want to officially support it … after all it doesnt make much sense to use a 1GB board with arm64 in production (you will quickly run out of ram due to the binaries occupying nearly twice the amount at runtime) but it is surely a good way to do arm64 development and test builds.
The Pi Foundation/Broadcom (upstream) does something similar in providing the 64bit boot firmware but not officially supporting it …
When i try using this json file for a build for a 64-bit Raspberry Pi image, i run the ‘snap sign’ cmd, etc, still, i get this error:
ubuntu-image -O rpi3_arm64.img --channel=edge pi3_arm64.model
Warning: for backwards compatibility, ubuntu-image falls back to ubuntu-image snap if no subcommand is given
error: cannot fetch and check prerequisites for the model assertion: cannot add assertion model (ubuntu-core-18-pi3-64; series:16 brand-id:kaiwan-billimoria): error finding matching public key for signature: found public key "DIST … " from "WJu … " but expected it from: kaiwan-billimoria
COMMAND FAILED: snap prepare-image --channel=edge pi3_arm64.model /tmp/tmp_a91rt83/unpack
the model assertions for Core images are stored next to the images at:
just grab ubuntu-core-18-arm64+raspi3.model-assertion from there …
if you want to roll your own model assertion. make sure that the assertion and the gadget you use use the same brand-id (and that it is associated with a valid login.ubuntu.com account)