Custom core20 image: boot error: file '/kernel.efi' not found

device
3

Yes, that works very well, thank you for your answer!

The next step would be to create a custom image with a custom kernel, for that I cloned the ubuntu-focal kernel repository (https://kernel.ubuntu.com/git/ubuntu/ubuntu-focal.git) and built the kernel snap. Now the model assertion uses the grade “dangerous” and contains a local rebuilt kernel snap, it looks like:

{
    "type": "model",
    "series": "16",
    "authority-id": "my-id",
    "brand-id": "my-id",
    "model": "custom-ubuntu-core-20-amd64",
    "architecture": "amd64",
    "timestamp": "2021-02-17T20:33:40+00:00",
    "base": "core20",
    "grade": "dangerous",
    "snaps": [
        {
            "name": "pc",
            "type": "gadget",
            "default-channel": "20/stable",
            "id": "UqFziVZDHLSyO3TqSWgNBoAdHbLI4dAH"
        },
        {
            "name": "ubuntu-focal-kernel",
            "type": "kernel"
        },
        {
            "name": "core20",
            "type": "base",
            "default-channel": "latest/stable",
            "id": "DLqre5XGLbDqg9jPtiAhRRjDuPVa5X1q"
        },
         {
            "name": "snapd",
            "type": "snapd",
            "default-channel": "latest/stable",
            "id": "PMrrV4ml8uWuEUDBT8dSGnKUYbevVhc4"
        },
        {
            "name": "htop",
            "type": "app",
            "default-channel": "latest/stable",
            "id": "hJmReLmgXSUj4SF7WhyTVRV6IzUa4QUZ"
        }
    ]
}

But after creating and booting the image, the same error happens:

error: file '/kernel.efi' not found.

It seems that only the kernel snap from the track 20 works well, if another kernel snap is used it fails booting.

What configuration could be missing in the kernel snap that could help fixing this error?

Thanks.