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Re: [Xen-devel] [RFC][PATCH][0/4] Intel(R) Trusted Execution Technologys

To: "Joseph Cihula" <joseph.cihula@xxxxxxxxx>
Subject: Re: [Xen-devel] [RFC][PATCH][0/4] Intel(R) Trusted Execution Technologysupport: Overview
From: "Jan Beulich" <jbeulich@xxxxxxxxxx>
Date: Wed, 29 Aug 2007 09:09:09 +0100
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Edwin Zhai <edwin.zhai@xxxxxxxxx>, James Xu <james.xu@xxxxxxxxx>, Shane Wang <shane.wang@xxxxxxxxx>, xense-devel@xxxxxxxxxxxxxxxxxxx, Gang Wei <gang.wei@xxxxxxxxx>
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>o  Xen's command line must include the 'no-real-mode' option to prevent
>Xen from reading the e820 table from BIOS.  The TXT code makes
>modifications to the table passed via GRUB that the Xen portions of the
>code need.

This doesn't sound like something that is only a temporary workaround.
However, suppressing real mode execution has its own issues:
- There are known issues with GrUB properly passing the E820 table, meaning
  that Xen would use incorrect (truncated) memory information if it is prevented
  from getting the information from the BIOS directly.
- There is more than just the E820 information retrieved while in real mode,
  and this information is known to be required in certain cases for proper
  functioning of Dom0.
So I think this needs to be addressed in some way.


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