From: Grant Grundler <grundler@parisc-linux.org>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Ray Lee <ray-lk@madrabbit.org>,
torvalds@linux-foundation.org,
Andrew Morton <akpm@linux-foundation.org>,
Faidon Liambotis <paravoid@debian.org>,
Matt Domsch <Matt_Domsch@dell.com>,
"Siddha, Suresh B" <suresh.b.siddha@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Jesse Barnes <jbarnes@virtuousgeek.org>,
bugzilla-daemon@bugzilla.kernel.org,
bugme-daemon@bugzilla.kernel.org, bero@arklinux.org,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] intel-iommu: Work around yet another BIOS bug
Date: Thu, 20 Aug 2009 15:47:12 -0600 [thread overview]
Message-ID: <20090820214712.GA26360@lackof.org> (raw)
In-Reply-To: <1250796740.3311.2.camel@macbook.infradead.org>
On Thu, Aug 20, 2009 at 08:32:20PM +0100, David Woodhouse wrote:
> On Thu, 2009-08-20 at 12:29 -0700, Ray Lee wrote:
> > Think about changing this to a warning that "Your IOMMU appears to be
> > disabled." All ones is, after all, the traditional hint that the
> > device is turned off.
>
> Hints are all very well, but the BIOS provided an ACPI table explicitly
> telling us that there was an active IOMMU at this location.
Could that be to reserve address space that the "disabled" IOMMU
might still be responding to?
Ie the BIOS hides the control registers so the OS won't talk to the
device but the IOMMU might still attempt to lookup certain address ranges.
I'm more inclined to believe it's sloppiness on the part of the BIOS
writers but thought this might be an alternative explanation.
thanks,
grant
next prev parent reply other threads:[~2009-08-20 21:47 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-14003-10286@http.bugzilla.kernel.org/>
2009-08-19 21:26 ` [Bugme-new] [Bug 14003] New: Infinite loop on bootup while handling DMAR Andrew Morton
2009-08-20 1:15 ` Suresh Siddha
2009-08-20 7:52 ` David Woodhouse
2009-08-20 8:01 ` [PATCH] intel-iommu: Work around yet another BIOS bug David Woodhouse
2009-08-20 9:44 ` Andrew Morton
2009-08-20 11:14 ` David Woodhouse
2009-08-20 18:48 ` Andrew Morton
2009-08-20 12:36 ` Matthew Wilcox
2009-08-20 19:29 ` Ray Lee
2009-08-20 19:32 ` David Woodhouse
2009-08-20 21:47 ` Grant Grundler [this message]
2009-08-20 21:54 ` David Woodhouse
2009-08-31 13:15 ` Carl-Daniel Hailfinger
2009-08-20 8:40 ` [Bugme-new] [Bug 14003] New: Infinite loop on bootup while handling DMAR Faidon Liambotis
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