Rosenzweig: Writing an open source GPU driver – without the hardware

Here's a
war story from Alyssa Rosenzweig on the process of writing a free
driver for Arm's 'Valhall' GPUs without having the hardware to test it on.

In 2021, there were no Valhall devices running mainline
Linux. While a lack of devices poses an obvious obstacle to device
driver development, there is no better time to write drivers than
before hardware reaches end-users. Developing and distributing
production-quality drivers takes time, and we don’t want users to
be reliant on closed source blobs. If development doesn’t start
until a device hits shelves, that device could reach “end-of-life”
by the time there are mature open drivers. But with a head start,
we can have drivers ready by the time devices reach end users.