A recent OS on the old Asus C201P

There are people that easily sell and swap computers. I get somewhat attached to them, which explains why I have a growing collection of old gear. Even my first beige PC with a Cyrix CPU has been restored and boots!

The Asus C201P is special because it came from the US via a friend. Because Chromebooks were a niche product and you could barely find them 10 years ago. Kinda like today.

It is a very old machine now and can barely browse the web because there are no ChromeOS updates for it anymore. But... it's a functional laptop with a working battery!

So it needed a Linux on it.

There are quite a few blogs and articles about getting this to work and if you would open it up you could even flash Libreboot on it easily (with the risk of bricking it).

For starters, booting from an SDCard seems sufficient and thus I went about getting proper Debian to work on this little fellow.

The main problem has been that the Chromebook wants a specific partition layout and a modern kernel with all the modules wouldn't fit in the small boot partition. The other problem is that the kernel needs to be signed, so a kernel update on the Linux side would break unless you re-sign it.

My solution to this was to sign an U-Boot bootloader and then launch Linux. This way Debian kernel updates don't need any work.

Of course, this does break the security chain the Chromebooks had. Which is not a big problem for an old laptop and it's comparable with a normal PC.

So, here it is: https://github.com/emilianbold/c201p . A very small project that builds the signed U-Boot as well as the ARM Debian 13 image.

This makes the C201P a normal computer again. There's Firefox and a terminal and everything one needs works.

Interestingly, the machine has a Hantro G1 Video Processing Unit (VPU) which supports some video formats. But out of the box, neither Firefox (for Youtube) nor VLC use it. Decoding is all done on CPU and a normal video uses about 70% of it.

This VPU does have a working driver though and I could find a gstreamer command that explicitly uses the right hardware based decoder. With this decoder, a video playback is only 10% CPU and the VPU takes care of the rest.

Which goes to show how important dedicated hardware is and how little we use of it.