I try to switch from nvidia to nouveau driver via script:

!/bin/bash

stop gdm

rmmod nvidia

sed -i "s/nouveau/nvidia/" /etc/modprobe.d/blacklist-nvidia-nouveau.conf

update-alternatives --set gl_conf /usr/lib/mesa/ld.so.conf ldconfig

modprobe nouveau

cp /etc/X11/xorg.conf{.nouveau,}

start gdm

and driver is loaded and X started but compiz it doesn't. In .xsession-errors I see:

Compiz (opengl) - Fatal: Root visual is not a GL visual compiz (opengl) - Error: initScreen failed compiz (core) - Error: Couldn't activate plugin 'opengl' Compiz (opengl) - Fatal: Root visual is not a GL visual Compiz (opengl) - Fatal: Root visual is not a GL visual Compiz (opengl) - Fatal: Root visual is not a GL visual Compiz (opengl) - Fatal: Root visual is not a GL visual Compiz (opengl) - Fatal: Root visual is not a GL visual Compiz (opengl) - Fatal: Root visual is not a GL visual Compiz (opengl) - Fatal: Root visual is not a GL visual Compiz (opengl) - Fatal: Root visual is not a GL visual gnome-session[19075]: WARNING: App 'compiz.desktop' respawning too quickly gnome-session[19075]: WARNING: Application 'compiz.desktop' killed by signal gnome-session[19075]: WARNING: App 'compiz.desktop' respawning too quickly

what I'm doing wrong??