Created attachment 373982 [details]
Xorg.log

Description of problem:

Black screen in X with F12                                                                                                                                                           
                                                                                                                                                                                     
Environment:                                                                                                                                                                         
                                                                                                                                                                                     
Matrox G550                                                                                                                                                                          
TFT with 1280x1024 resolution at DVI connector                                                                                                                                       
                                                                                                                                                                                     
How to reproduce:                                                                                                                                                                    
                                                                                                                                                                                     
Boot Fedora-12-i686-Live-KDE                                                                                                                                                         
Display ends up with black screen and parameter out of range info.                                                                                                                   
Switching to text console with ALT-F2 seems to work but new output                                                                                                                   
corrupts the display. Toggling between ALT-F1 and ALT-F2 restores                                                                                                                    
temporary the console display till next output.                                                                                                                                      
                                                                                                                                                                                     
Observations:                                                                                                                                                                        
                                                                                                                                                                                     
The default mode of the matroxfb kernel driver seems to be the culprit.                                                                                                              
In dmesg is this:                                                                                                                                                                    
                                                                                                                                                                                     
matroxfb 0000:01:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16                                                                                                                    
matroxfb: Matrox G550 detected                                                                                                                                                       
matroxfb: MTRR's turned on                                                                                                                                                           
matroxfb: 640x480x8bpp (virtual: 640x26214)                                                                                                                                          
matroxfb: framebuffer at 0xFA000000, mapped to 0xf8000000, size 33554432                                                                                                             
fbcon: MATROX (fb0) is primary device                                                                                                                                                
fb0: MATROX frame buffer device                                                                                                                                                      
                                                                                                                                                                                     
"video=matroxfb:vesa:0x11B" from kernel doc matroxfb.txt on the                                                                                                                      
kernel command line seems to have no effect because matroxfb_base is                                                                                                                 
loaded as a module. But "matroxfb_base.vesa=0x11B" does the trick.                                                                                                                   
                                                                                                                                                                                     
In dmesg is this:                                                                                                                                                                    
                                                                                                                                                                                     
matroxfb 0000:01:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16                                                                                                                    
matroxfb: Matrox G550 detected                                                                                                                                                       
matroxfb: MTRR's turned on                                                                                                                                                           
matroxfb: 1280x1024x32bpp (virtual: 1280x3276)                                                                                                                                       
matroxfb: framebuffer at 0xFA000000, mapped to 0xf8000000, size 33554432                                                                                                             
fbcon: MATROX (fb0) is primary device                                                                                                                                                
fb0: MATROX frame buffer device                                                                                                                                                      
                                                                                                                                                                                     
The text console and X are now working as expected.                                                                                                                                  
Xorg.log is identical with and without "matroxfb_base.vesa=0x11B"                                                                                                                    
"vga=795" on the kernel command line is also working.                                                                                                                                
But this involves kernel vesafb and kernel matroxfb fails to start.