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

[J Mo <jmomo@jmomo.net>]

I played around with this issue a little bit more. This is what I learned:

I booted from a fresh drive I installed Debian Testing on and it does 
not seem to be affected by this issue. That's notable.

I was not able to revert to EXA on the ZBox/Radeon HD 8250 system. The 
xorg log says that mode is not supported on this hardware.

I also tried enabling glamor on the NVida GTX 970 and that failed, 
saying something like "glamor initialization failed" in the log. I 
didn't think glamor was supported there anyway, so I'm not surprised.

I moved this installation to a system which has an Radeon HD 5770 in it 
and I am not seeing any similar issues here.

Finally, I probably won't be able to test this again in the future as I 
am planning on putting that ZBox to use and won't have access to it for 
awhile.



On 04/25/2016 04:09 AM, J Mo wrote:
> Thanks for the advice. I had tried putting a config snip very similar 
> to this into /etc/X11/xorg.conf.d, but now that I think about it, I 
> think I included the Driver line, which might have broken it. I'll try 
> it again exactly as you specified.
>
>
>
>
> On 04/25/2016 02:53 AM, Julien Cristau wrote:
> > 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.