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.
