Archive for December, 2008

Xserver issues: 96 dpi vs. 133 dpi, nv vs. nvidia

December 22, 2008

Since some weeks I occasionally run Intrepid Ibex on my Lifebook (booting from my test partition). I installed the box with defaults only. Having
lulu:/home/bav> lspci | grep -i nvidia
01:00.0 VGA compatible controller: nVidia Corporation GeForce 8400M G (rev a1)

Intrepid used the free nv-Driver:

lulu:/home/bav> less /var/log/Xorg.0.log
...
(II) LoadModule: "nv"
(II) Loading /usr/lib/xorg/modules/drivers//nv_drv.so
...

This worked, but surprisingly I got


(==) NV(0): DPI set to (96, 96)

which is simply wrong. The Lifebook has 133 dpi.

As I could not fix this, I quickly installed the nonfree NVIDIA binary Xorg driver, package nvidia-glx-177.

With this driver, I got correctly 133 dpi. Everything seemed fine …

I then realized, that changing the screen’s brightness no longer worked. It worked fine as long as I used the free nv driver. Now with the nonfree NVIDIA driver, the screen did not change brightness any longer.

Unfortunately there are situations, where the Lifebook’s screen stays dark (e.g. maybe after disconnecting from docking station). As I was not able to switch the screen brighter I had to reboot in this situation 😦

I uninstalled nvidia-glx-177 and started over with nv. Changing values in /proc/acpi/video/VGA/LCD/brightness worked as seen before but I was not able to find the right place to start X with 133 dpi.

Finally I got the tip to use Xfce 4 Settings Manager | User Interface | DPI. It had the value System Default. After I changed it all XFCE and Gnome applications were fine. Firefox and Thunderbird too.
Some other (e.g. emacs) still need some fine tuning.

I have no idea what xfce does here behind the scenes. Obviously the X-Server stills runs with 96dpi …

Complex systems tend to appear full of mystery …

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