Date: Sat, 19 Nov 2011 19:11:06 +0100
From: =?utf-8?B?VG9tw6HFoSBKYW5vdcWhZWs=?= <tomi@nomi.cz>
To: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: linux-kernel@vger.kernel.org, Wey-Yi Guy <wey-yi.w.guy@intel.com>,
	linux-wireless@vger.kernel.org
Subject: Re: iwlagn: memory corruption with WPA enterprise
Message-ID: <20111119181106.GA5515@nomi.cz> (sfid-20111119_191116_730685_0AAFD68E)
References: <20111109155411.GA1669@nomi.cz> <20111109165158.GA2254@redhat.com> <20111110091816.GA2247@nomi.cz> <20111110114732.GA2217@redhat.com> <20111110125347.GA29415@nomi.cz> <20111110160703.GA2775@redhat.com> <20111110163051.GA24533@nomi.cz> <20111111054731.GA2292@redhat.com> <20111111150105.GA25437@nomi.cz> <20111114140714.GD2513@redhat.com>
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In-Reply-To: <20111114140714.GD2513@redhat.com>
Sender: linux-wireless-owner@vger.kernel.org

Hello,

On Mon, Nov 14, 2011 at 03:07:15PM +0100, Stanislaw Gruszka wrote:
> On Fri, Nov 11, 2011 at 04:01:05PM +0100, Tomáš Janoušek wrote:
> > Could you please elaborate on that thing with enabling IOMMU? The only thing I
> > know about IOMMU is that it is somehow related to VT-d (passing whole PCI
> > devices to virtual guests), and that I have to pass intel_iommu=off to kernel
> > command line, otherwise the machine doesn't even boot. Is that a problem?
> Yes. That mean iommu software or hardware is broken on your system.
>
> I have no other ideas how to track this down. I think now, this is
> a firwmare issue. BTW, you suspected that from very beginning :-)
> This could be also a driver issue, but AFAICT programing DMA do not
> differ on 6205 from other devices, so bug in firmware is much more
> probable reason of corruption.

I have some news. I got IOMMU to work, because I identified the problem [1]
and disabled firewire-ohci for the time being completely, but I'm not sure
what do I need to do to make it catch the problem. I assumed that all I need
is to intel_iommu=on and then all devices do DMA stuff in isolation, but I can
still reproduce the issue without the smallest hint of an error in dmesg. Does
it tell us anything, or shall I enable some more debugging stuff?

[1] http://thread.gmane.org/gmane.linux.kernel.pci/8765/focus=1217800

Anyway, I didn't get to trying 2.6.38/39 yet, but I will do that soon. It is
also safe to say now that x86_64 is completely unaffected, as I was running
various 64bit kernels the whole week without a single failure.

Regards,
-- 
Tomáš Janoušek, a.k.a. Liskni_si, http://work.lisk.in/