Re: RFC: ProtocolLib for cross DXE and SMM Protocol and Handle Services

["Cohen, Eugene" <eugene@hp.com>]

Mike,
 
> Can you provide examples in EDK II today where the same GUID Value
> and Structure definition
> are used in both the UEFI Handle Database and the SMM Handle
> Database.

The example exists in our internal code right now.  We have two platform families: one with SMM and one without.  We have a library, originally developed as a DXE library, that use a protocol to determine a secure boot policy setting.  This library is linked against our variable driver.  In our non-SMM system the variable driver runs as a Runtime DXE component and the policy protocol referenced is published in the Boot Services protocol DB.  In our SMM system the variable driver runs in SMM and the policy protocol is published in the SMM protocol DB.  The protocol is identical and uses the same GUID.  So in this scenario we don't install the protocol simultaneously in both environments, rather we have different platforms where the protocol resides on one side or the other.  Since this protocol is really simple (it's not using events, TPL or depending on UEFI boot services stuff) it works well for this model.
 
> I am aware of cases where an SMM Driver looks for protocols in the
> DXE Handle database,
> but I don't think your proposed lib would cover that case.

Correct - in our usage we are trying to discourage the cross-pollination of SMM and DXE in this way since security minded people get nervous when SMM executes outside of the secure sandbox.

Thanks,

Eugene