I still have not figured out why the OpenChrome DRM drm-next-4.20 branch is not working. Looked at I2C bus subsystem related code commit, but could not really find a commit that will cause a crash like what I observed. As an experiment, played around with Linux 4.18 rc6 to see how it will perform. The good news is that this version is working, and in fact, I am writing this post from the computer I used to compile the code (VIA Embedded EPIA-M830 with VIA Nano 1 GHz). I will test Linux 4.18 rc7 shortly. Since I went back to performing full compilation, it might take a few hours to compile the code and test it.
I moved the OpenChrome DRM development into drm-next-4.20 branch more than a week ago, but I discovered that when OpenChrome DRM is being used, it can no longer boot the OS.
The reason for this is due to a strange bug introduced by I2C bus subsystem device driver between Linux 4.18 rc4 and rc7. The matter was not resolved by upgrading to Linux 4.19 rc1. I have tried to find the offending commit of I2C bus subsystem, but I am not able to find the bad commit so far. I contacted the I2C bus subsystem maintainer, but he denied that “core” I2C bus subsystem device driver has changed recently. Generally speaking, the I2C bus subsystem maintainer did not show much interest in the issue when I reported the issue to him directly via e-mail. I guess I will have to go bisect the issue myself.