Posts: 9
Joined: Wed Dec 06, 2017 3:57 am

Want to try out the latest Anholt kms driver

Sun Dec 10, 2017 10:40 am

... but I don't know where to get started.

I'm currently running the official 4.14 beta kernel. I would like to stay with 4.14 and not go back to 4.9.

I have a full development environment and am comfortable building kernels and anything else that needs to be built, so I shouldn't need too much hand-holding, but I don't know which pieces I need. In particular...

1) I know the github where he keeps his work is here, but I don't know which branch is the "right" one, or in general what the different branches mean.
2) Is the driver entirely contained within a kernel source tree or are there other pieces to it?
3) Do I need any special firmware, device-tree files or other magic bits that aren't included in the latest Stretch?
4) Which version of the KMS driver is included with the 4.14 beta?

Posts: 3
Joined: Sat Dec 02, 2017 7:10 pm

Re: Want to try out the latest Anholt kms driver

Sun Dec 10, 2017 5:23 pm

There is a step-by-step guide here:

https://github.com/anholt/mesa/wiki/VC4 ... an-upgrade

Now if you're trying this, it is nice to have the serial port connected. Otherwise you might be left with a Pi that for all purposes appears dead after changing the kernel. If you plan on doing a lot of development and testing, it's worthwhile to setup the uboot bootloader and an NFS share so you can do network boot. This also makes cross compiling much easier as you can just install the files to the NFS share on your computer instead of trying to get them onto the SD card.

Specifically to your question:
1) The branches there are really just for development, testing ideas. They are not meant as releases to be used. If you want the latest version as such, you can just use torvalds/linux master and then maybe apply individual patches you want to try.
2) There is a kernel part which does the low-level HW interaction and the mode setting stuff, and then there is the userland part in Mesa (https://www.mesa3d.org/) that does shader compilation and all the OpenGL (and GLES) stuff.
3) If you follow the guide from above, there isn't anything else you should need. Remember to deactivate any overlays, those really only apply to the RPi foundation kernel.
4) Whatever version was in the official 4.14 kernel when they branched off. Notice the driver itself isn't really versioned.

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