Re: Xorg tearing fix on Intel HD Graphics 4000

[Roel Janssen <roel@gnu.org>]

Mark H Weaver writes:

> 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.

Thanks for your response! I look forward to finding out what this bug
is.  If you do, please let us know.

>
> 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!

FWIW, I get equal frames per second in SuperTuxKart and Armagetron.
Anyway, there's nothing like experiencing it yourself of course.

Kind regards,
Roel Janssen