Seems like several packages missed in sl-source repo:

bfa-firmware-3.0.3.1-1.el6.src.rpm
libX11-1.5.0-4.el6.src.rpm
libXau-1.0.6-4.el6.src.rpm
libXaw-1.0.11-2.el6.src.rpm
libxcb-1.8.1-1.el6.src.rpm
libXcomposite-0.4.3-4.el6.src.rpm
libXcursor-1.1.13-2.el6.src.rpm
libXdamage-1.1.3-4.el6.src.rpm
libXdmcp-1.1.1-3.el6.src.rpm
libXevie-1.0.3-4.el6.src.rpm
libXext-1.3.1-2.el6.src.rpm
libXfixes-5.0-3.el6.src.rpm
libXfont-1.4.5-2.el6.src.rpm
libXft-2.3.1-2.el6.src.rpm
libXi-1.6.1-3.el6.src.rpm
libXinerama-1.1.2-2.el6.src.rpm
libXmu-1.1.1-2.el6.src.rpm
libXpm-3.5.10-2.el6.src.rpm
libXrandr-1.4.0-1.el6.src.rpm
libXrender-0.9.7-2.el6.src.rpm
libXres-1.0.6-2.el6.src.rpm
libXScrnSaver-1.2.2-2.el6.src.rpm
libXt-1.1.3-1.el6.src.rpm
libXtst-1.2.1-2.el6.src.rpm
libXv-1.0.7-2.el6.src.rpm
libXvMC-1.0.7-2.el6.src.rpm
libXxf86dga-1.1.3-2.el6.src.rpm
libXxf86misc-1.0.3-4.el6.src.rpm
libXxf86vm-1.1.2-2.el6.src.rpm
mesa-9.0-0.7.el6.src.rpm
mesa-dri1-drivers-7.11-8.el6.src.rpm
xcb-proto-1.7-2.el6.src.rpm
xorg-x11-drv-geode-2.11.13-1.el6.src.rpm
xorg-x11-drv-neomagic-1.2.7-3.el6.src.rpm

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Best regards,
Elena