linux-kernel - Re: 2.6.27-rc8-git8: oops in process hald-addon-dell-backlight (intel iommu related?)

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Date:	Sat, 25 Oct 2008 01:25:54 +0200
From:	Frederik Himpe <fhimpe@...enet.be>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: 2.6.27-rc8-git8: oops in process hald-addon-dell-backlight
 (intel iommu related?)

On vr, 2008-10-24 at 23:49 +0200, Rafael J. Wysocki wrote:
> On Wednesday, 8 of October 2008, Frederik Himpe wrote:
> > On Wed, 08 Oct 2008 20:15:37 +0000, Frederik Himpe wrote:
> > 
> > > On my Dell Latitude E6400 system with Intel chipset and graphics, I get
> > > this oops in my 2.6.27-rc8-git8 based kernel, which probably happens
> > > when hald-addon-dell-backlight is started.
> > > 
> > > Complete dmesg and lspci info:
> > > https://qa.mandriva.com/show_bug.cgi?id=44711
> > 
> > Booting with intel_iommu=off seems to fix this issue, and seems to make my 
> > e1000e based network card stop from giving "transmit timed out" errors 
> > after which it stopped working.
> 
> Is it necessary to boot 2.6.27 final on this box with intel_iommu=off, and if
> so, is it still necessary in mainline?

I just tested stock 2.6.27.3 and this machine (Dell Latitude E6400) is
totally unusable without intel_iommu=off if Intel VT is enabled in the
BIOS. During the boot process, stack traces start scrolling over the
screen. In the end, it goes on starting X, and from that moment, the
machine locks up completely. Booting in runlevel 3, I see lots of stack
traces (too much to even be able to read them).

In the past (with Mandriva's 2.6.27-rc) it would at least succeed in
booting (with one or a few backtraces), but even then the e1000e network
card would timeout a few seconds after when starting to transfer some
data, after which the network was totally unusable until a reboot. A
reader of my blog confirmed having the same problem on this same type of
laptop and also solving it by using intel_iommu=off.

I entered some more information here:
http://bugzilla.kernel.org/show_bug.cgi?id=11821

-- 
Frederik Himpe <fhimpe@...enet.be>

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