"Auto Graphics API for Linux" is broken or at least misleading

"Auto Graphics API for Linux" is broken or at least misleading, because it seems to result in "Use OpenGL Core and if the GPU driver doesn't have the necessary OpenGL feature level, crash."
It leads to predictably instant-crashing with X-related errors on my Intel Skylake GPU which has a moderate but not exciting OpenGL "3.3 (Core Profile)" support according to glxinfo.
Forcing the OpenGL2 legacy backend makes it launch just fine.

If this is instead a driver issue, then it might be worth informing bugzilla.freedesktop.org over it..

 

I attached the full glxinfo output of the affected Intel GPU

 

What does the crash look like? Is it failing to create an opengl core context, or is it crashing for some other reason?

 

Player.log attached. It shows some crash backtrace things that will hopefully answer your question

 

Hm, we're trying to create a glx context, your driver is calling into X, then xcb is hard-aborting because it thinks it received some requests out of sequence. It'll take more investigation to determine whether the driver is at fault or we are, and to nail down the proper fix or workaround.

Does running in glcore mode with -force-gfx-direct produce the same behavior?

 

Yes, -force-gfx-redirect seems to lead to a windowed mode startup but then the same crash (also Assertion `!xcb_xlib_threads_sequence_lost' failed. in the Player.log)

For what it's worth, I tested another machine which is a laptop, also with Intel Skylake-generation graphics (i5-6200U) and Fedora Linux 23, and it shows the same issue as my Desktop with Intel Skylake-generation graphics (i7-6700) and Fedora 23 where I initially tested this on. So whatever it is, it seems to reproduce more or less consistently on at least Intel Skylake graphics machines (haven't tested other Intel generations) and Fedora 23 x86_64 with the Gnome 3 Window Manager. (in case that helps you possibly reproducing this issue if you want to try that)

 

Did you run with -force-gfx-redirect or -force-gfx-direct ? -force-gfx-direct is the correct argument.

 

Just to make sure I tried again, and still the same:

 

Hello, I have the same problem here, the application closes at launch with a "SIGABRT" signal.

The only way to make it work is starting the application with "-force-opengl" but it causes the application to look really bad.

 

I ran into the same issue. I have Intel HD 3000, whose official Linux drivers cap at OpenGL 3.1 (just below the Unity requirements for the OpenGL Core backend). If I generate a standalone Linux binary in Unity 5.4.0b15, it only works when launched with the `-force-opengl` option or when I put OpenGL2 above OpenGLCore in the Graphical APIs part of Player settings.

This does not seem to be a problem specific to the experimental Linux editor. The current version of Stephen's Sausage Roll on Steam, for example, crashes on startup as well, unless I use `-force-opengl`.

Is the intended behavior of standalone Linux builds running on machines with older GPUs to crash on startup when not using the `-force-opengl` option (I have seen people on this forum being told to use `-force-opengl` but I did not find any open issue in the bug tracker)? Is support for the OpenGL2 backend being discontinued?

If this is not intended behavior and since it is not tied to the Linux Editor, should we post a new issue? The only relevant issues on the tracker have already been marked as solved in previous versions:

https://issuetracker.unity3d.com/is...0-fails-with-unsupported-opengl-version-error
https://issuetracker.unity3d.com/is...-startup-after-screen-dialog-in-32bit-machine

 

There is some sort of race condition.

For Stephen's Sausage Roll, if I run it with gdb and put a breakpoint on glXCreateContextAttribsARB (even if I just continue immediately), the game works correctly. If I run with gdb without any breakpoints, the game fails with the X error (which I found is BadMatch).

 

Facing same problem