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Message-ID: <20090703082111.GD21833@elte.hu>
Date: Fri, 3 Jul 2009 10:21:11 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Pavel Machek <pavel@....cz>
Cc: Joseph Cihula <joseph.cihula@...el.com>,
linux-kernel@...r.kernel.org, arjan@...ux.intel.com, hpa@...or.com,
andi@...stfloor.org, chrisw@...s-sol.org, jmorris@...ei.org,
jbeulich@...ell.com, peterm@...hat.com, gang.wei@...el.com,
shane.wang@...el.com
Subject: Re: [RFC v6][PATCH 4/4] intel_txt: force IOMMU on for Intel(R) TXT
launch
* Pavel Machek <pavel@....cz> wrote:
>
> On Tue 2009-06-30 19:31:10, Joseph Cihula wrote:
> > The tboot module will DMA protect all of memory in order to ensure the that
> > kernel will be able to initialize without compromise (from DMA). Consequently,
> > the kernel must enable Intel(R) Virtualization Technology for Directed I/O
> > (VT-d or Intel IOMMU) in order to replace this broad protection with the
> > appropriate page-granular protection. Otherwise DMA devices will be unable
> > to read or write from memory and the kernel will eventually panic.
> >
> > Because runtime IOMMU support is configurable by command line options, this
> > patch will force it to be enabled regardless of the options specified, and will
> > log a message if it was required to force it on.
> >
> >
> > dmar.c | 7 +++++++
> > intel-iommu.c | 17 +++++++++++++++--
> > 2 files changed, 22 insertions(+), 2 deletions(-)
> >
> > Signed-off-by: Joseph Cihula <joseph.cihula@...el.com>
> > Signed-off-by: Shane Wang <shane.wang@...el.com>
>
> NAK. Breaks user expectations, misses docs updates.
What's your proposed solution? If an incompatible IOMMU option is
specified should the kernel to disable TXT and panic?
Ingo
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