Radeon HD 6790 not booting LMDE 201109

[GerMulvey]

Issue: LMDE gnome 64 will not boot to live desktop (RC did same)
Hardware: amd athlon 2 x4, 4gb ddr3, Radeon HD 6790

The process stops at garbled colors to the bottom third of the screen. It is probably the desktop at a wacky setting.
I have tried

put “– radeon.modeset=0″ in the kernel line without quotes, it’ll boot smoothly. Suggested by manmath sahu

But the result was the same only a more uniform color lol. In both normal and compatibility modes. "nomodeset" has no effect either.
Any ideas please?

Update: seems I run into the same issue in Kubuntu 11.10
I have now managed to get kubuntu to install but then get the same issue again and still can not get to the desktop. Also using an nvidia card all works fine!
Also tried - http://www.x.org/wiki/radeonBuildHowTo#Troubleshooting - no change (although I feel this is where the issue is most likely)
This seems to also be affecting other current distros like opensuse 12.1 m5, Kubuntu 11.10 beta

[GerMulvey]

I have identified the cause as the radeonhd driver....

in other distros it is now possible to get to an install or desktop

adding nomodeset blacklist=radeon 3 to the boot will allow the ubuntu 11.10 livecd to boot to a tty at which adding flgrx then startx gets you to the desktop. Install and repeat above gets you up and running with a working install.

This may be relevent in Mint 12 when it becomes available.