Guys i need to notice the RadeonSI boards work on quad g5,
i have tested a Sapphire RadeonHD 7750 (pcie 2.x board)
and it is working in FBdev mode without issue.
But if mesa glemouregl are call from xorg and radeon system freeze with gliches.

I fixed it renaming the glemourgl module of xorg in
it made xorg dont open it... in this way you will able to have radeon driver working for 2D accelerations.

Note: The Glamouregl crash in all ppc big endian world
hope someone will fix it.