File README.updates of Package Mesa
DRI Driver update mechanism --------------------------- If any corresponding DRI driver is found in "/usr/lib/dri/updates/" it will be favored over the one in "/usr/lib/dri/" and will be used for 32/64 bit applications. On 32/64 bit biarch platforms additionally a corresponding DRI driver in "/usr/lib64/dri/updates/" will be favored over the one in "/usr/lib64/dri/" and will be used for 64bit applications.