xorg-x11-drv-ati for Fedora 10 fails to setup DRI for 3520x1600x32 screen, is this normal?

[Alex Villací­s Lasso]

Alex Deucher escribió:
> On Thu, Feb 12, 2009 at 11:59 AM, Alex Villací­s Lasso
> <a_villacis at palosanto.com> wrote:
>
>   
>> As you can see, my primary (and only) screen is using a resolution of
>> 1440x1080, the maximum one it supports. But the DRI calculation is being
>> done on 3520 x 1600. Is this the normal behavior of the X server and the
>> radeon driver? I am not really sure, so I am asking here instead of
>> filing a bug. Is there any directive on xorg.conf I can use to reduce
>> the xrandr maximum so that it can fit within the DRI calculation for my
>> system?
>>     
>
> This is normal.  We can't dynamically resize the desktop yet, so we
> use the virtual parameter to pre-allocate a large enough buffer for
> for the maximum desktop size requested.  Use a smaller virtual line in
> your xorg.conf.
>
> Alex
>
>   
I have used the Virtual setting and it works (DRI is now enabled). 
However, I had no Virtual setting before, and the 1440x1080 mode was the 
biggest one configured in my xorg.conf :

Section "Screen"
        Identifier "Screen0"
        Device     "Videocard0"
        Monitor    "Monitor0"
#       DefaultDepth     24
        SubSection "Display"
                Virtual    1440 1080
                Viewport   0 0
                Depth     24
                Modes     "1440x1080" "1400x1050" "1440x1024" "1440x900" 
"1280x1024" "1280x960" "1280x800" "1152x864" "1152x768" "1024x768" 
"800x600" "640x480"
        EndSubSection
EndSection

The xorg.conf manpage states that the default for Virtual is supposed to 
accomodate all the screen modes defined. For my case, it should be set 
to 1440x1080, but chose those bogus values instead. Where did the 
xserver get those values from?

-- 
perl -e '$x=2.3;printf("%.0f + %.0f = %.0f\n",$x,$x,$x+$x);'