Re: Cannot reconfigure xserver-xorg after upgrade to testing (Etch)

[Florian Kulzer <florian@molphys.leidenuniv.nl>]

Chris Lale wrote:
> I upgraded from Sarge to Etch using apt-get dist-upgrade. Now I cannot
> reconfigure my xserver using dpkg-reconfigure xserver-xorg. The changed
> settings are remembered between dpkg-reconfigure sessions (ie saved to
> /etc/X11/XF86Config-4), but are not implemented. I cannot get a clean
> reinstall either. Here is the detail.
>
> 1. Purge xorg
> I have tried to reinstall xserver-xorg, but it will not purge cleanly -
> there are errors reported by the postrm script.
>
>    # apt-get --purge xserver-xorg
>
>    Removing xserver-xorg ...
>    xserver-xorg prerm warning: X server provided by xserver-xorg package is
>       being removed; setting /etc/X11/X to point to /bin/true
>    Purging configuration files for xserver-xorg ...
>    Removing any system startup links for /etc/init.d/xserver-xorg ...
>       /etc/rcS.d/S71xserver-xorg
>    dpkg: error processing xserver-xorg (--purge):
>      subprocess post-removal script returned error exit status 128
>    Errors were encountered while processing:
>      xserver-xorg
>    E: Sub-process /usr/bin/dpkg returned an error code (1)

That is a bug in the post-removal script:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=351326
I am not convinced that it is necessary for you to purge xorg, since
your problem seems to come from some "leftovers" of xfree86 or it is an
intrinsic problem with the configuration of xorg.

> 2. Install xorg
> During apt-get install xserver-xorg, xserver-xfree86 debconf values are
> migrated
>
>    # apt-get --purge install xserver-xorg
>    Preconfiguring packages ...
>    xserver-xorg config warning: Migrating xserver-xfree86 debconf values to
>       xserver-xorg.
>
> dpkg--reconfigure offers a choice of two xservers to configure (even
> though xserver-xfree86 is not installed). It does this twice, and no
> other configuration screens are offered. I chose xserver-xorg both times.
>
>    Select the desired default X server.
>    xserver-xorg
>    OK
>
>    Selecting previously deselected package xserver-xorg.
>    (Reading database ... 153676 files and directories currently installed.)
>    Unpacking xserver-xorg (from 
> .../xserver-xorg_6.9.0.dfsg.1-4_i386.deb) ...
>    Setting up xserver-xorg (6.9.0.dfsg.1-4) ...
>    xserver-xorg config warning: Migrating xserver-xfree86 debconf values to
>       xserver-xorg.
>
>    Select the desired default X server.
>    xserver-xorg
>    OK
>
>    Adding system startup for /etc/init.d/xserver-xorg ...
>       /etc/rcS.d/S71xserver-xorg -> ../init.d/xserver-xorg
>
> I now have a working xserver using the nv driver (I originally
> configured X for my Nvidia card in Sarge).

Maybe it would be better to purge xfree86; it is a bit worrying that
debconf offers it as an option if it is no longer installed. I still
would expect that dpkg-reconfigure xserver-xorg should work nonetheless.

> 3. Reconfigure
>
>    # dpkg-reconfigure xserver-xorg
>
> Video display defaults to vesa. (It is possible to select nv, but I
> still end up with a flickering vesa display.)
>
>    xserver-xorg postinst warning: overwriting possibly-customised 
> configuration
>       file; backup in /etc/X11/xorg.conf.200602271117
>    System startup links for /etc/init.d/xserver-xorg already exist.
>
> I cannot change the default vesa setting and get my nv setting back. I
> have tried
>    # md5sum /etc/X11/XF86Config-4 >| /var/lib/xfree86/XF86Config-4.md5sum
> before using dpkg-reconfigure, and

For xorg this should be done with /etc/X11/xorg.conf. As far as I know
this will only be relevant for automatic upgrades; dpkg-reconfigure will
always overwrite the file. (That also seems to be the case for you: You
get a warning, the original config file is saved under a different name
and the new settings replace the old ones.)

>    # dexconf -o /etc/X11/XF86Config-4
> after dpkg-reconfigure, without success.

First of all, if the automatic reconfiguration does not work as
expected, you can always edit the file /etc/X11/xorg.conf manually and
specify whatever driver you like. However, I would suggest that you
first check if you have the following packages installed: "discover",
"mdetect" and "xresprobe" (plus "laptop-detect" if we are talking about
a laptop). These packages help with the hardware detection and the
initial setup of xorg.conf. If one or more are missing on your computer,
install them and try "dpkg-reconfigure xserver-xorg" again. If you are
lucky this will fix your problem.

> Can anyone suggest how I could get a clean reinstall of X, without
> migrating my old xfree86 settings?

If everything else fails you can rename the file /etc/X11/XF86Config-4
so that Debian can no longer recognize it as the old configuration file.
I do not think this is the cause of your troubles, though; after all,
the original migrated configuration did use the nv module and worked,
right?

Regards,
          Florian