iMac12,1 does not show graphics on screen [with workaround]

iMac12,1 (the sort of hardware we'd really like to support well out of the box) with Radeon GPU plays the welcome sound but does not show graphics on the screen.

Thanks [__- CRYPTiCEXiLE -__ on YouTube](https://www.youtube.com/watch?v=UU-7Z7TkBT4).

__Workaround:__
At bootloader prompt, need to type:

```
load radeonkms
load drm
boot
```

It would be interesting to know whether it works out-of-the-box in NomadBSD.

In the installed system:

> edit the /etc/rc.conf where it has the .ko of the intel drivers at the end of the list just take that out and replace it with radeonkms.ko instead it should work