Bug#822523: xorg: Xorg -configure fails: "Number of created screens does not match number of detected devices."

[Julien Cristau <jcristau@debian.org>]

On Sun, Apr 24, 2016 at 21:55:12 -0700, J Mo wrote:

> Package: xorg
> Version: 1:7.7+15
> Severity: normal
> 
> I have Zotac ZBox Nano CA320 which uses an AMD APU with a Radeon HD 8250. It's an Intel NUC-like system, and this chip is commonly found on laptops.
> 
> I have X running KDE5 (sddm) successfully but am troubleshooting another video bug. I wanted to turn off AccelMethod glamor (the default) to find out if the admgpu/radeon driver was causing some artifacts when glamor mode was active (as opposed to EXA).
> 
> I tried shutting down sddm and then running "Xorg -configure", but that fails with the "Number of created screens does not match number of detected devices." error. I have attached the log from that session. The output Xorg.conf.new file looks fairly complete, but no configuration that I've tried works. The only thing that will get X working successfully is no manual configuration.
> 
> I've also tried just dropping config bits into /etc/X11/xorg.conf.d/ and anything short of a blank file causes Xorg to fail.
> 
> If we read here:
> https://wiki.debian.org/Xorg#What_if_I_do_not_have_an_xorg_config_file.3F
> 
> This is apparently a fairly common and well-known problem, but there doesn't seem to be any resolution that I was able to find. The advice on the wiki link above is non-helpful.
> 
> So, what now?
> 
Yes, Xorg -configure is known broken.  Don't use that.  Just write

Section "Device"
        Identifier "glamor"
        Option "AccelMethod" "glamor"
EndSection

to /etc/X11/xorg.conf.