R3.2-rc2: random reboots on Lenovo T520 (workaround)

[yaqu]

After upgrade from R3.0 to R3.2-rc2, my T520 started rebooting randomly
a few times a day. Sometimes after 10 minutes of running, sometimes
after 12 hours, but always with nothing in logs.

After a long and boring investigation I have found out it was triggered
by connecting external monitor and it can be fixed by disabling the
Intel i915 RC6 feature (some power saving stuff).

Since I've added i915.enable_rc6=0 as a kernel parameter
(GRUB_CMDLINE_LINUX in /etc/default/grub) I have a 50 hours of uptime
and counting :-)

Affected hardware:
Lenovo ThinkPad T520
cpu: Intel(R) Core(TM) i5-2520M CPU @ 2.50GHz
chipset: Mobile Intel QM67 Express
gpu: Intel HD Graphics 3000

Relevant results from lspci:
00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor
Family DRAM Controller (rev 09)
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation
Core Processor Family Integrated Graphics Controller (rev 09)

Qubes 3.2-rc2, kernel 4.4.14-11

Does anyone else have similar issue with i915?

--
yaqu

[Simon]

Hello Yaqu,

> Does anyone else have similar issue with i915?

I have the impression that latest Qubes OS hardly supports i915
chipsets.

On my side, on a Lenovo T500 after a normal boot process when the X
server
should start the screen goes blank and there is no more disk activity
(no log
either) letting me think of some deep crash / freeze somewhere.
Hopefully this
laptop offers a second ATI based graphical chipset, so once I solved
Qubes/Fedora over-heating issue with this one (`radeon.dpm=1' for those
interested) I managed to install an use Qubes.

It can be worth to noting that on the same laptop I had no issue to use
Qubes 2
with Intel i915 graphical chipset (this was actually my first workaround
against the afore mentioned ATI over-heating issue), and that latest
Fedora
Live CD does not cause any issue either. So this i915 issue is really a
Qubes
or Xen specific issue.

Moreover, if you check the issue list, you will find yet another issue
still
related to i915 handling, "Graphic woes / i915 - Intel Graphics 5500 on
T450s":

https://github.com/QubesOS/qubes-issues/issues/2232

Good luck...

Simon.

[yaqu]

On Fri, 23 Sep 2016 09:48:29 +0200, Simon
<qubes...@whitewinterwolf.com> wrote:

> Hello Yaqu,
>
> > Does anyone else have similar issue with i915?
>
> I have the impression that latest Qubes OS hardly supports i915
> chipsets.

I'm not sure if these problems are really Xen/Qubes specific - there
is a lot of bug reports for various issues (GPU hangs, system freezes,
reboots) with i915 on Linux (miscellaneous distros and kernel versions).

> It can be worth to noting that on the same laptop I had no issue to
> use Qubes 2

Same for me - no serious hardware related issues while using R2 and
R3.0.

> Moreover, if you check the issue list, you will find yet another
> issue still
> related to i915 handling, "Graphic woes / i915 - Intel Graphics 5500
> on T450s":
>
> https://github.com/QubesOS/qubes-issues/issues/2232
>
> Good luck...

Luckily, it looks like disabling RC6 has fixed my problems. Right
now, after 3 days of uptime and multiple suspend/resume cycles, I've had
no reboots and I can use external monitor again :-)

Setting i915.enable_rc6=0 works for me.

--
yaqu