pc386 BSP on board with UMA

Gedare Bloom gedare at gwu.edu
Thu Dec 10 10:31:54 CST 2009

On Wed, Dec 9, 2009 at 8:58 PM, Chris Johns <chrisj at rtems.org> wrote:
> Joel Sherrill wrote:
>> On 12/09/2009 06:16 PM, Chris Johns wrote:
>>> Joel Sherrill wrote:
>>> Interesting manual. Seems to assume you know what TSEG, SMM etc is.
>> I found SMM .. System Management Mode.  (I think)
> Yes found this. What about TSEG and CSEG ?
Hi, I've read a little bit about SMM in a paper about how to exploit
it, here is a link to a blog article by the author, where you can find
more details: http://theinvisiblethings.blogspot.com/2009/03/attacking-smm-memory-via-intel-cpu.html

>From the paper linked at that blog, there is the following explanation:
"TSEG is a region of memory above 1MB comprising the SMRAM (in fact
most of the SMM code is located in TSEG in today's systems). The start
of the TSEG region is indicated by the TSEGMB register in the
northbridge, on Intel systems."
Where SMRAM is the SMM memory, which has to be protected somehow,
since SMM runs at a very high privilege.

And from what I understand, CSEG just means "code segment".

Unfortunately, I don't have any insight on what you are trying to do.
Sounds like a pain though! :)


... (snipped)

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