well, today i (partially) realized why my basic drivers don’t work: the preinstalled packages amdgpu and amdgpu-dkms seem to not work due to amdgpu-dkms being unconfigured. tried configuring it and got the same error. around about there my system stopped using even the iGPU and i had to uninstall some other drivers (thanks @[email protected] )
The R9 380 was a rebrand of the R9 285, which was the first card to require the use of the new amdgpu driver. The R9 390 was a rebrand of the R9 290, which did not force the use of amdgpu, but optionally supports it through a kernel flag.
Source: I have an R9 380.
Ah, makes a lot of sense.