Re: Xorg tearing fix on Intel HD Graphics 4000

[Mark H Weaver <mhw@netris.org>]

Hi Roel,

Roel Janssen <roel@gnu.org> writes:

> Ricardo Wurmus writes:
>
>> Hi Roel,
>>
>>> With the following patch to the Xorg configuration file, I have a
>>> tear-free GuixSD experience.  I wonder if this is upstreameable in some
>>> way.  This patch is probably too broad in effect.  Can I change it so
>>> that only the graphics card I have will be affected by this patch?
>>
>> I’m not sure about this, but you can apply it only to your system by
>> changing the slim-service’s “startx” value like this:
>>
>> --8<---------------cut here---------------start------------->8---
>>     (modify-services %desktop-services
>>       (slim-service-type
>>        config => (slim-configuration
>>                   (inherit config)
>>                   (startx (xorg-start-command
>>                            #:configuration-file
>>                            (xorg-configuration-file
>>                             #:extra-config
>>                             (list your-fix)))))))
>> --8<---------------cut here---------------end--------------->8---
>>
>> But I suppose what you want is to apply it unconditionally in Guix and
>> have the X server ignore it for all but this one graphics card, right?
>
> No, not necessarily.  I could no longer do 'guix pull && guix system
> reconfigure ...', which I attempted to solve by upstreaming this patch.
>
> I wonder if anyone else is having the same problem on this hardware..  

I have the same problem on my Thinkpad X200.  For me, it mostly only
happens in Emacs graphical frames, and only within GNOME (and I suppose
maybe other compositing window managers, though I haven't tried), but
the problem for me is quite severe.  I've resorted to running Emacs in
text mode within GNOME Terminal, because otherwise I cannot trust my
editing at all (e.g. I'm not sure if I'm deleting the messages that I
intend to delete in Gnus).

However, your proposed workaround is not a proper fix, and I don't think
we should apply it system-wide in Guix.  I don't think it would be
accepted upstream.  I think there's a real bug somewhere, most likely in
Emacs itself, but possibly in the Intel graphics drivers.

It's good to have the workaround though.  I may apply it to my own
system and see how it affects graphics performance.  Thank you!

      Mark