[OpenBIOS] l440gx+ nvram writing ...

[David Christensen]

Ron,

In case you're not aware, the SMI is the System Management Interrupt.  When
an SMI is asserted, the CPU will enter SMM, System Management Mode.  It is a
special mode of the CPU that was originally designed to make it easier for
the BIOS to perform power management functions.  The SMI is completely
transparent to the OS and cannot be masked.  The code that is executed in
SMM is stored in a special memory area called SMRAM (generally mapped at
A0000h-BFFFFh) and cannot be accessed unless operating in SMM (there is
usually a lock bit in Intel chipsets that is set and cannot be cleared
without resetting the system, this is to protect the SMI handler from being
modified).  The only way to modify the code in the SMI handler is to write
your own BIOS.  If you have a good hardware ICE then you could step through
the SMI handler and find out where the FMUP signature, or you could try
reverse engineering the FMUP utility.  In either case you have a good deal
of work ahead of you.

Dave

-----Original Message-----
From: owner-openbios at elvis.informatik.uni-freiburg.de
[mailto:owner-openbios at elvis.informatik.uni-freiburg.de]On Behalf Of
Ronald G. Minnich
Sent: Monday, February 07, 2000 10:40 AM
To: openbios at elvis.informatik.uni-freiburg.de
Subject: [OpenBIOS] l440gx+ nvram writing ...


more.

You can enable/disable smi_l in the bios. I'm going to check that today.
If smi_l is disabled, your OS will never know that the BUD asserted an
interruptt when you tried to write the BIOS>


The remaining question, of course, is what you're supposed to do with that
interrupt, but that's next.

it's rather amazing, but intel is shipping a server motherboard that
REQUIRES DOS to be upgraded. You have to wonder sometimes, what are people
thinking? The only exisiting SMI_L interrupt handler is in the BIOS!

ron



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