Bug 388712

Summary: Highly unstable default Intel HD driver xorg-video-intel-modesetting
Product: [KDE Neon] neon Reporter: Mahendra Tallur <mahen>
Component: Packages User EditionAssignee: Neon Bugs <neon-bugs>
Status: RESOLVED FIXED    
Severity: crash CC: jr, neon-bugs, sitter
Priority: NOR    
Version First Reported In: unspecified   
Target Milestone: ---   
Platform: Neon   
OS: Linux   
Latest Commit: Version Fixed In:
Sentry Crash Report:

Description Mahendra Tallur 2018-01-09 09:09:28 UTC 
Hi ! 

Using a Kaby Lake machine (Intel HD 630), Neon (user) uses by default the xserver-xorg-video-intel-modesetting driver for Intel HD Graphics. It was I think backported by the Neon team to get better performance than the default Ubuntu HD graphics driver.

However, I figured out this driver would make my machine EXTREMELY unstable : several X crashes per day. 

On the same machine I had no crash at all within a year with an Nvidia card. I switched back to the Ubuntu driver xserver-xorg-video-intel-hwe which is based on a March GIT version (contrary to the Neon default one  which is from the September GIT version) and have a perfectly stable desktop.

Please note that before completely freezing the X server, strange phenomenoms begin to appear that could make one think there is something wrong with kwin. (black flickering, windows resizing themselves or not reacting properly to events). But as it only happens with this specific driver  and leads to a complete freeze, I think it's way lower in the stack. 

I also run Neon on other machines using other Intel HD graphics (HD 3000 or 4000). They do not seem to suffer from the instability.

Do other people use this driver with a Kaby Lake Intel Graphics ? Would you consider switching back to a safer / more supported driver by default ?

NOTE 1 : I made also tons of tests : clean install, X edgers PPA, updated Intel microcode, etc. No difference at all. The crash even occurs when just using Thunderbird / Firefox with no special configuration (no accelerated layers). OIn the contrary, with the HWE driver, I can stress the GPU a lot (Steam games etc) and get no crash.

NOTE 2 : ALL intel drivers (the Neon native modesetting of the Ubuntu HWE) ALSO suffer from slow performance, even when compositing is disabled, in many games. Phenomenon that doesn't occur under the Wayland session where all simple games are fast & smooth. I didn't test the stability under Neon but as I guess it doesn't use the X driver, it's not supposed to crash :-)
Comment 1 Mahendra Tallur 2018-01-09 09:13:19 UTC 
(My NOTE 2 is related to Kaby Lake HD Graphics performance ; some games ran much better on my 5+ y.o HD 3000 than my 1 y.o HD 630. But this is just a remark, my bug is about stability.)
Comment 2 Mahendra Tallur 2018-01-09 20:13:05 UTC 
My initial bugreport contains a big mistake. 

The xserver-xorg-video-intel-modesetting driver is a dummy package. So when this one is selected, X actually makes use of the i915 driver and forces kernel mode-setting driver, so, theorically, this should be the driver built into the Ubuntu HWE kernel.

However I get the crashes whatever kernel version I use : 4.10 HWE or 4.13 HWE.

It would be logical the "xserver-xorg-video-intel-hwe" packages also made use of the aforementioned driver but without the kernel mode-setting, but it's apparently a different one (the package does contain some .so files)

To sum up I don't know if the crashes are due to driver versions or the use of KMS.
Comment 3 Mahendra Tallur 2018-01-16 10:09:47 UTC 
The instability now constantly occurs whatever package I use. It seems related to the fact Ubuntu LTS jumped from kernel 4.10 to 4.13 to apply the Meltdown fix... (?) Maybe modesetting is now always on ? To work around this I temporarily put back my Nvidia card.

MEANWHILE I figured out my wife's laptop, which also is a Kaby Lake one (HD 520), doesn't suffer at all from the instability issue (very same software stack).
Comment 4 Mahendra Tallur 2018-10-21 21:20:05 UTC 
Well, I cannot reproduce it anymore with newer kernels / Intel drivers (HWE in KDE Neon 16.04 or current Neon 18.04). I guess it can be considered as resolved :)