Major freezing issues with Uburmix 3.0 on Acer Travelmate B115 (WORKAROUND tho)

[NickT]

I recently installed Ubermix 3.0 on my Acer B115 and it quickly started suffering from complete freezes where nothing (including mouse cursor) would do anything, forcing a restart of the computer using the power button. The freezes would occur between 5 minutes and an hour of booting up the machine - generally closer to 5 minutes.

After some research and failed attempts to fix the problem by installing a new kernel, I came across the workaround that works. Turns out the problem has affected many people and is well documented, but there is a workaround - not a fix, as it causes the machine to be much less power efficient.

The issue is that many Intel Bay Trail machines with kernels newer than Linxu 3.16 have been suffering these system freezes. I see Urku flagged this in comments under the Ubermix 3.0 arrival blog with this link:
https://www.phoronix.com/scan.php?page=news_item&px=Intel-Linux-Bay-Trail-Fail

The workaround is to alter the grub.cfg by adding "intel_idle.max_cstate=1". I found the most useful guide to doing this (although pressing "SHIFT" to acces the POST didn't work - I needed to use "ESCAPE") was this:
http://andylinuxblog.blogspot.co.at/2016/05/asus-aspire-ubuntu-freezing-issue.html

With the workaround, it appears my machine is now working happily, but thought I better share to save others the big headaches I've been suffering trying to fix the issue.





   

[urkomasse]

Hi,


I am running my Asus TP200SA (or E205SA) laptops with standard Ubuntu for this reason. By applying the latest kernel 4.7.2 from the Ubuntu Mainline Kernel PPA, I have managed to get very stable machines, without the cstate parameter.


That parameter turns off powersaving features of the processor, which can increase heat and shortens battery life.
So... I guess it would be great if Jim could make a kernel for Ubermix based on 4.7.2

[urkomasse]

I am testing today with the latest standard kernel of Ubuntu 16.04, 4.4.0-34, and it seems very stable. I think the Ubuntu kernel developers may have backported the fixes.

This is great news for a lot of people out there


EDIT: Looks like I spoke too soon. According to the kernel bug report, people are still experiencing the freezes with kernel 4.4.0-34.
I am going to test kernel 4.6.7 (I am having a separate issue with ath10k_pci wifi and kernel 4.7.2, so I am hunting for a better kernel).
According to the bug report kernel 4.6.3 or higher has solved the issue as well.

[urkomasse]

I may have found a really really really good solution:
https://bugzilla.kernel.org/show_bug.cgi?id=109051#c436


Two scripts are provided by the author of that post, a couple of posts above (and again right below).
One of them disables all C6 power-saving states, and enables the C7 states. Apparently Bay Trail Intel CPUs have a bug with C6 states.
Using this script from /etc/rc.local, you should be able to run Bay Trail devices with standard kernels, without any parameters, and still with battery saving.
I will test later, but it sounds really good!