Ok, the workaround works, I had troubles because I tried the ppa xorg-edgers dirvers to see if they fix the thing...
So with the Ubuntu's official repositories, and disabling the modesetting with the kernel parameter options (I am not sure wether the ForceEnablePipeA option is required) seems very effective.
However this bug is still problematic because :
* It makes KMS unusable
* The newer releases of xorg intel driver seem to require KMS, so if this is not fixed upstream there will be a problem with no workaround for future Ubuntu releases...
Ok, the workaround works, I had troubles because I tried the ppa xorg-edgers dirvers to see if they fix the thing...
So with the Ubuntu's official repositories, and disabling the modesetting with the kernel parameter options (I am not sure wether the ForceEnablePipeA option is required) seems very effective.
However this bug is still problematic because :
* It makes KMS unusable
* The newer releases of xorg intel driver seem to require KMS, so if this is not fixed upstream there will be a problem with no workaround for future Ubuntu releases...