When X/kdm do not start properly

These problems go into the pile labeled, "duh, I should have tried that first." Inevitably when I make changes to the graphics hardware or complete a new install of gentoo I get to the final stage of starting X and am left with a black screen (the monitor is still receiving a signal, there's just nothing there). Usually I check Xorg.0.log and kdm.log and find that there were no issues. In this case it probably means I forgot to set the opengl renderer.

# eselect opengl set ati

After a reboot the system comes right up into kde.

The second variation is an old school X cursor, but nothing else resembling a gui (black screen), and Xorg.0.log whines about fglrx_dri.so. In this case I needed to switch the order of the graphics cards in my xorg.conf. The below command spits out the graphics adapters, and the first column is the information we want to put into xorg.conf. In this case I already had the correct pci-e device numbers, but I had them in the wrong order. A simple swap of 2:0:0 and 6:0:0 in xorg.conf (NOTE the syntax change when putting these into xorg.conf) and everything was back to functional. (SIDE NOTE: removing a graphics adapter can alter these numbers, in this rig with one card it sits at 05:00.0)

# lspci | grep -i vga

02:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Tahiti XT [Radeon HD 7970]

06:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Tahiti XT [Radeon HD 7970]

xorg.conf lines

Section "Device"

        Identifier  "aticonfig-Device[0]-0"

        Driver      "fglrx"

        BusID       "PCI:6:0:0"

EndSection

Section "Device"

        Identifier  "aticonfig-Device[1]-0"

        Driver      "fglrx"

        BusID       "PCI:2:0:0"

EndSection