From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tom Wimmenhove <tom.wimmenhove-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Subject: Re: Regression since 4.1
Date: Mon, 4 Apr 2016 17:06:11 +0000 (UTC)
Message-ID: <loom.20160404T185813-468@post.gmane.org>
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Joerg Roedel <joro@...> writes:

> 
> Hi Tobias,
> 
> On Thu, Dec 10, 2015 at 12:07:57AM +0100, Tobias Geiger wrote:
> > It all comes down to kernel > 4.1 && iommu=on = not working here
> > 
> > Hardware is:
> > Intel DX58SO, Intel CPU i7 920... all pretty solid running for years 
now, 
> > always with iommo=on.
> > 
> > I'd love to debug this further, just dont know how...
> 
> Sounds like only bisecting the issue will help here. You can find an
> introduction on bisecting here:
> 
> 	https://git-scm.com/book/en/v2/Git-Tools-Debugging-with-Git
> 
> Would be great if you can find the time to bisect the issue.
> 
> 	Joerg
> 
> 

I can confirm this bug with kernel "4.2.0-16-generic #19-Ubuntu" on an 
Intel DX58SO board with a W3520 Xeon CPU.
Before I was running 3.16.0 which did not lock up at boot but did have 
occasional DMAR issues with GPU passthrough while running a Windows 7 gues 
in Qemu. I don't know if the two are related.