Programming the gpu on nanoPI M1

Hi,

I am attempting to software render some gui for a custom OS on nanoPi M1.

The reference manual gives me the gpu address, but not how to give a buffer
I would like it to draw on screen.

For example, on raspberry pi, there are some mailboxes (addresses the gpu
monitors) we write into.

If someone has an idea, please don't keep it for yourself :)

Thanks,

Bye