Weston on Raspberry Pi

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2023-03-18 10:00:04

One of the platforms we’ve been working on for a while at Collabora is the Raspberry Pi. Obviously the $25 pricepoint makes it hugely appealing to a lot of people — including free software developers who up until now have managed to avoid the agonyjoy we experience on a daily basis working on embedded and mobile platforms — but there are a couple of aspects which speak specifically to us as a company.

Firstly, we did quite a bit of work on OLPC through the years, which had a similar, very laudable, educational mission encouraging not just deep computer literacy in children, but also open source involvement. The Raspberry Pi has broadly the same aims, a very education-friendly pricepoint, and has seen huge success.

Less loftily, it’s a great example of a number of architectures we’ve been quietly working on for quite some time, where hugely powerful special-purpose (i.e. not OpenGL ES) graphics hardware goes nearly unused, in favour of heavily loading the less powerful CPU, or pushing everything through GL.

The Raspberry Pi has a Broadcom BCM2385 SoC in it, containing an extremely beefy (roughly set-top-box-grade) video, media and graphics processor called the VideoCore (somewhat akin to a display controller, GPU and DSP hybrid), and a … somewhat less beefy general-purpose ARMv61 CPU. The ARM side does everything you’d expect, whereas the VideoCore is a multi-functional beast, acting as the GPU for OpenGL ES, the display engine for outputs/overlays/etc, and also any general-purpose processing (e.g. accelerated JPEG decode).