Endless log spam _CGXGLDisplayContextForDisplayDevice: No matching context for device

[BMT]

Disregard.

[mcousins]

I seem to have stopped the log spam by adding this to my asl.conf in /etc at the top of the file

? [= Sender WindowServer] ignore

And then performing the sudo kill -HUP [PID of process]

Not sure if that's OK, I tried the other way of creating a file under the asl folder and that did nothing for me.

Hope this helps, even if its just towards finding a better answer!

[ehendrix]

I changed it a little bit to:

# WindowServer messages about display context (caused by DisplayLink driver)
? [= Sender WindowServer] [= Level Warning] [A= Message _CGXGLDisplayContextForDisplayDevice] claim only

Seems to be working and ensures that any other messages from WindowServer are still going in.

[ehendrix]

No more messages since I've put this in. Interesting that with all the complaining about this within the forums that DisplayLink was never able to provide this as a solution.
Is it perfect? No.
Is it something Apple should fix? yes
Does the work-around work? Heck yes.
Could DisplayLink provide the work-around? Don't see why not.

[Carlo]

Hi ehendrix,

Sorry for going quiet on this one. Yes we think this is a good workaround, we could apply it at install time.

We'd use
? [= Sender WindowServer] [=S Message_CGXGLDisplayContextForDisplayDevice] ignore

Unless anyone can spot any issue with the approach?

Cheers,
Carlo

[jb510]

Originally Posted by Carlo

Hi ehendrix,

Sorry for going quiet on this one. Yes we think this is a good workaround, we could apply it at install time.

We'd use
? [= Sender WindowServer] [=S Message_CGXGLDisplayContextForDisplayDevice] ignore

Unless anyone can spot any issue with the approach?

Cheers,
Carlo

Note that the above declaration is missing a space between Message and _CGX... should be

? [= Sender WindowServer] [=S Message _CGXGLDisplayContextForDisplayDevice] ignore

[BMT]

Originally Posted by Carlo

Hi ehendrix,

Sorry for going quiet on this one. Yes we think this is a good workaround, we could apply it at install time.

We'd use
? [= Sender WindowServer] [=S Message_CGXGLDisplayContextForDisplayDevice] ignore

Unless anyone can spot any issue with the approach?

Cheers,
Carlo

Hi Carlo, the string you proposed is formatted incorrectly, it would need to be as follows instead else it won't work:
? [= Sender WindowServer] [S= Message _CGXGLDisplayContextForDisplayDevice] ignore

I've confirmed the above works as intended.

PS. Make sure to put the string at the top of asl.conf else it won't work! (Due to other rules taking priority over it and cancelling out the effect). I'm not sure if S= or =S (as you proposed) makes any difference, but I've only ever seen it as S= which is why I put it that way round.

Also, if you're thinking of doing this automatically you should make sure to check there's not already a string containing _CGXGLDisplayContextForDisplayDevice OR WindowServer in asl.conf, as people may have already added the same or a different string to stop it from happening already.

Edit: Looks like someone else beat me to it, I've been trying to post this for the past few days but kept getting forum errors each time I did. The 4th page of the topic wasn't even showing up until I posted my message! Weird.

[Carlo]

Thank you BMT and others,

Will take your advice, hopefully won't find issues with this change.

Cheers,
Carlo

[jb8748]

Originally Posted by ehendrix

I changed it a little bit to:

# WindowServer messages about display context (caused by DisplayLink driver)
? [= Sender WindowServer] [= Level Warning] [A= Message _CGXGLDisplayContextForDisplayDevice] claim only

Seems to be working and ensures that any other messages from WindowServer are still going in.

Thank you ehendrix. That does look like a better command - I'm no expert on the logging so I was finding things that worked. I've updated my blog post.

James

[ehendrix]

Originally Posted by jb8748

Thank you ehendrix. That does look like a better command - I'm no expert on the logging so I was finding things that worked. I've updated my blog post.

James

As I see it, this was all team work. I would have never come to this if it weren't for your blog post and postings from others. :-)