kldload amdgpu on Vega64 halts the system

[amiramix]

I know about the issue with drm-kfbsd12.0-kmod on 12.1. I found it when I tried to fix the issue I am seeing.

I am using one system to build the kernel, world and packages and another, a desktop, to install them.

The build system is running AMD Phenom and NVidia graphics card. I am using poudriere to compile packages. The build system and the poudriere jail are running FreeBSD-12.1-RELEASE-p3. On the build system I have also compiled a new kernel and world from FBSD-12.1-RELEASE-p3 sources.

On the desktop where I am loading the module I have used FreeBSD-base packages to install the kernel and world compiled on the build system. The desktop is running on AMD Ryzen with Vega 64 graphics card.

Initially the desktop was running a stock version of FreeBSD-12.1-RELEASE-p3 with Generic kernel and the drm-kfbsd12.0-kmod build on the build system. The behaviour is the same regardless if I am using GENERIC kernel/world or my own.

I am logging in either as single or multi user into the command line. Then

kldload amdgpu

On the screen I see a bunch of drivers being loaded. There is a few loaded for vega_10... then the screen goes blank. The system is halted. Any SSH session are now defunct. Only power off/on is able to restart it.

I am happy to collect some debug information if you tell me how.