I experimented with different versions of the kernel. With versions 4.9.0 and 4.9.6 the freeze is followed by every GUI process segfaulting. With kernel 4.8.0, there are still freezes, but after a while the applications become responsive again.

Also, when installing a kernel, update-initramfs generates the following warnings:

W: Possible missing firmware /lib/firmware/i915/kbl_guc_ver9_14.bin for module i915
W: Possible missing firmware /lib/firmware/i915/bxt_guc_ver8_7.bin for module i915

I don't know if they are related to the freezes, though.

The guc is not needed for current hardware -- you can ignore that error.

Can you try with latest version of kernel from drm-tip (https://cgit.freedesktop.org/drm/drm-tip/), xf86-video-intel (https://cgit.freedesktop.org/xorg/driver/xf86-video-intel/) and latest Mesa (https://mesa.freedesktop.org/archive/).

Moreover, if this is still occurring, to confirm what is causing it, can you also try with modesetting driver (https://cgit.freedesktop.org/xorg/driver/xf86-video-modesetting) rather than Intel DDX (ie xf86-video-intel) and let us know the status? 

Provide your config and change current status to:
- RESOLVED/* if you cannot reproduce.
- REOPENED otherwise; attach fresh gpu error dump, kernel log & xorg log


* Details:
- Kernel: 4.9.0-040900-generic
- Platform: Skylake (PCI ID: 0x1916, PCI Revision: 0x07, PCI Subsystem: 103c:81a1)
- Mesa : [Please confirm your version]
- xf86-video-intel : [Please confirm your version]

(In reply to yann from comment #4)
> Can you try with latest version of kernel from drm-tip
> (https://cgit.freedesktop.org/drm/drm-tip/), xf86-video-intel
> (https://cgit.freedesktop.org/xorg/driver/xf86-video-intel/) and latest Mesa
> (https://mesa.freedesktop.org/archive/).
> 
> Moreover, if this is still occurring, to confirm what is causing it, can you
> also try with modesetting driver

Note that this was occurring with -modesetting.

(In reply to Chris Wilson from comment #5)
> (In reply to yann from comment #4)
> > Can you try with latest version of kernel from drm-tip
> > (https://cgit.freedesktop.org/drm/drm-tip/), xf86-video-intel
> > (https://cgit.freedesktop.org/xorg/driver/xf86-video-intel/) and latest Mesa
> > (https://mesa.freedesktop.org/archive/).
> > 
> > Moreover, if this is still occurring, to confirm what is causing it, can you
> > also try with modesetting driver
> 
> Note that this was occurring with -modesetting.

thanks Chris. 
just for my knowledge/curiosity, is it because this is default Ubuntu 16.10 configuration or is this info available else where here?

It is the type of batch buffer in the error state.

(In reply to Chris Wilson from comment #7)
> It is the type of batch buffer in the error state.

thank so much :)

(In reply to yann from comment #4)
> Can you try with latest version of kernel from drm-tip
> (https://cgit.freedesktop.org/drm/drm-tip/), xf86-video-intel
> (https://cgit.freedesktop.org/xorg/driver/xf86-video-intel/) and latest Mesa
> (https://mesa.freedesktop.org/archive/).
> 
> Moreover, if this is still occurring, to confirm what is causing it, can you
> also try with modesetting driver
> (https://cgit.freedesktop.org/xorg/driver/xf86-video-modesetting) rather
> than Intel DDX (ie xf86-video-intel) and let us know the status? 
> 
> Provide your config and change current status to:
> - RESOLVED/* if you cannot reproduce.
> - REOPENED otherwise; attach fresh gpu error dump, kernel log & xorg log
> 
> 
> * Details:
> - Kernel: 4.9.0-040900-generic
> - Platform: Skylake (PCI ID: 0x1916, PCI Revision: 0x07, PCI Subsystem:
> 103c:81a1)
> - Mesa : [Please confirm your version]
> - xf86-video-intel : [Please confirm your version]

I don't mind trying with the latest versions of the components that you mentioned, but I need some help with that. I am a developer, so I an not completely clueless, but I know nothing about installing drivers that are not already packaged :)
However, I am willing to learn. Can you indicate where I can find information on how to compile and install these components?

Thanks

So at this stage Antoine, the issue you are facing is probably linked to Mesa. So you may start to update first your mesa version to the lastest: check http://www.mesa3d.org/download.html

(In reply to yann from comment #10)
> So at this stage Antoine, the issue you are facing is probably linked to
> Mesa. So you may start to update first your mesa version to the lastest:
> check http://www.mesa3d.org/download.html

I'll try that and report back. Thanks

So, I tried compiling mesa and installing it, but I think that I used the wrong prefix on the configure script, because ldconfig still reported that it would resolve the libraries from a different location than /usr/local/lib.
Then I tried to install them using a ppa that supposedly offers the latest versions. After that, my desktop environment (unity) ceased to work. I fiddled a lot, reverted the packages from the ppa and uninstalled the libraries that I had compiled myself, but it was still broken. In the end, I reinstalled the OS :S

The good news are that since I did a fresh install, I won't loose anything more if I need to reinstall again :)

So, before I try again, I may need more information on how to install the libraries. On my setup - Ubuntu 16.10 - each of the libraries seems to be in a different directory. What arguments should I pass to ./configure to ensure that it installs properly ?
Also, after installing, how can I confirm that the libraries that are in use are indeed the ones that I compiled ?

Thanks

(In reply to Antoine Aubry from comment #12)
> So, I tried compiling mesa and installing it, but I think that I used the
> wrong prefix on the configure script, because ldconfig still reported that
> it would resolve the libraries from a different location than /usr/local/lib.
> Then I tried to install them using a ppa that supposedly offers the latest
> versions. After that, my desktop environment (unity) ceased to work. I
> fiddled a lot, reverted the packages from the ppa and uninstalled the
> libraries that I had compiled myself, but it was still broken. In the end, I
> reinstalled the OS :S
> 
> The good news are that since I did a fresh install, I won't loose anything
> more if I need to reinstall again :)
> 
> So, before I try again, I may need more information on how to install the
> libraries. On my setup - Ubuntu 16.10 - each of the libraries seems to be in
> a different directory. What arguments should I pass to ./configure to ensure
> that it installs properly ?

Please start with http://www.mesa3d.org/autoconf.html & https://01.org/linuxgraphics/documentation/build-guide-0

> Also, after installing, how can I confirm that the libraries that are in use
> are indeed the ones that I compiled ?
> 
> Thanks
v

here check glxinfo ;)
https://dri.freedesktop.org/wiki/glxinfo/

Thank you for trying the latest mesa.  I'm sorry that it was so painful for you.

You can use mesa in the installed path (/usr/local/lib) by setting environment variables before launching the app from the command line:

$ export LD_LIBRARY_PATH=/usr/local/lib
$ export LIBGL_DRIVERS_PATH=/usr/local/lib/dri
$ pcbnew 

This application works fine for me on debian testing with mesa's tip and linux 4.9.  Is there some activity in the app that provokes your hang?

Thanks for the information. I will try that.

The hangs seem to happen when some part of the schematic is repainted. They tend to happen more while scrolling the view. Their frequency also seems to increase with time. After a reboot, it usually takes 5 to 10 minutes for the screen to freeze. But after a few freezes, they start to become much more frequent. Maybe it is due to some kind of resource leak.

If you can provide a sample schematic, I can try to scroll around and make it happen.

Created attachment 129284 [details]
Sample kicad project that reproduces the problem

Includes the entire kicad project. The actual issue occurs when opening mainboard.kicad_pcb in pcbnew. The fastest way to cause a freeze is to zoom in and out repeatedly using the mouse wheel. After a few tens of zooms, I get freezes consistently.

I forgot to say in my previous comment that I found that zooming in and out is even more likely to cause the freeze.

I attempted again to build mesa 13.0.3, which I believe is the latest version. After installing the library with make install, I tried running pcbnew as instructed:

$ export LD_LIBRARY_PATH=/usr/local/lib
$ export LIBGL_DRIVERS_PATH=/usr/local/lib/dri
$ pcbnew 

I observed no changes, the GPU still hangs. Btw, that this made my system unusable again. After logging off, the desktop manager would no longer start, just as before. I attempted to uninstall with "make uninstall", but that did not help. I has to reinstall the OS again to fix it. This is certainly an easily fixable problem, but I could not find out what was the problem.

I opened your file on my sklgt2, and was able to scroll/zoom for a *long* time with no gpu hangs.  I'm using debian testing with linux 4.9, modesetting, mesa 13.

There seems to be something else going on with your system, because installing mesa to /usr/local/ can not disable your system.  Encountering a GPU Hang can sometimes generate unrecoverable errors that require a reboot, but you should never need to reinstall.

It's troubling that this wouldn't work properly on Ubuntu with the oibaf ppa.  It would be good for someone else who uses Ubuntu can reproduce this with your kicad project.

Humm, I did not use the ppa that you mentioned. It was someone else's and maybe it was broken. I'll try with that one and report.
Thanks for testing with my files. In the configuration that you mention, you refer to "modesetting". What does this mean ?

There are a few ways to accelerate 2D graphics.  For Intel hardware, you can use:

 - SNA: xf86-video-intel, which accelerates the 2D api for Intel GPUs
 - Glamor/modesetting: implements the 2D api in OpenGL

Different distributions choose different defaults.  A GPU hang caused by Xorg can be caused by SNA or Mesa's implementation of the GL commands sent by Glamor.

Some Mesa GPU hangs have been recently fixed by:
180653c357d19ca88f7895f59874a58fac99cc53
Author:     Topi Pohjolainen <topi.pohjolainen@intel.com>
i965/blorp: Make post draw flush more explicit

Some SNA GPU hangs have been recently fixed by:
4acd4a7d3d2f41227022fa7581cfb85a0b124eae 
author	Chris Wilson <chris@chris-wilson.co.uk>
sna/gen9: Emit a dummy primitive between VertexElements

Make sure you use versions that have those patches.

For information on how to switch between sna and modesetting, see
https://bugs.freedesktop.org/show_bug.cgi?id=98999

So I installed the drivers from the oibaf ppa, and since then I ceased experiencing hangs!

Thank you so much for the patience and helpfuless. I really appreciate the time that you all took to explain the concepts to me.