i found a workaround here, its ok : https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-sis/+bug/301958/comments/43
-- sis 771/671 graphics board only works in vesa mode https://bugs.launchpad.net/bugs/332140 You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-sis in ubuntu. _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp
