The issue
On “desktop” linux installations there are limited options for the graphics stack, and most systems will run with the “open” Mesa graphics drivers and/or Nvidia drivers.
The IoT world is a bit more varied, often with device specific drivers provided by the board manufacturer. Ubuntu Frame is designed to work with graphics stacks that provide KMS, libgbm and an EGL supporting EGL_WL_bind_wayland_display.
It does this by using a Snap “content interface”, graphics-core20, that allows alternative drivers providing the facilities to be used. By default, Ubuntu Frame will use the mesa-core20 implementation of this interface which provides the Mesa drivers from the Ubuntu 20.04LTS Archive.
The example
The default provider can be overridden in a number of ways. Manufacturers will ideally do this through a brand store; but, it can also be done “by hand” on a device and that’s what we will describe here.
First we need an alternative graphics-core20 provider. As you won’t have access to a brand store we will use a test snap: kisak-core20. This is actually just a backport of a more recent version of Mesa, but it serves the purpose of illustrating this functionality.
Packaging graphics drivers as a snap isn’t something we discuss here. There’s details of the requirements in The graphics-core20 Snap interface, and the mesa-core20 and kisak-core20 snaps can be used as reference examples.
Setup
For this example, I’m going to show the steps using a desktop Linux installation. If you are working on an Ubuntu Core device it is actually simpler as the snaps involved will be running automatically.
First install the following:
snap install ubuntu-frame
snap install wpe-webkit-mir-kiosk
snap connect wpe-webkit-mir-kiosk:wayland
snap install --edge kisak-core20
Now (on desktop only) install Frame-it
snap install --classic frame-it
Frame-it is a utility to make it simpler running Ubuntu Frame from a desktop environment.
How to
You can see what’s connected to the graphics-core20 interface as follows:
snap interfaces | grep graphics-core20
kisak-core20:graphics-core20 -
mesa-core20:graphics-core20 ubuntu-frame,wpe-webkit-mir-kiosk
First check that things are working by running:
frame-it snap run wpe-webkit-mir-kiosk.cog
You can close this.
Next we can change switch the graphics provider:
snap disconnect ubuntu-frame:graphics-core20
snap disconnect wpe-webkit-mir-kiosk:graphics-core20
snap connect ubuntu-frame:graphics-core20 kisak-core20
snap connect wpe-webkit-mir-kiosk:graphics-core20 kisak-core20
And show the changes:
$ snap interfaces | grep graphics-core20
kisak-core20:graphics-core20 ubuntu-frame,wpe-webkit-mir-kiosk
mesa-core20:graphics-core20 -
And prove that it still all works:
frame-it snap run wpe-webkit-mir-kiosk.cog
