[RFC] VariablePolicy - Protocol, Libraries, and Implementation for VariableLock Alternative

Bret Barkelew <bret.barkelew@...>


VariablePolicy is our proposal for an expanded “VarLock-like” interface to constrain and govern platform variables.
I brought this up back in May to get initial comments on the interface and implications of the interface and the approach. We implemented it in Mu over the summer and it is not our defacto variable solution. It plugs in easily to the existing variable infrastructure, but does want to control some of the things that are currently managed by VarLock.

There are also some tweaks that would be needed if this were desired to be 100% optional code, but that’s no different than the current VarLock implementation which has implementation code directly tied to some of the common variable code.

I’ve structured this RFC in two pieces:

* The Core piece represents the minimum changes needed to implement Variable Policy and integrate it into Variable Services. It contains core driver code, central libraries and headers, and DXE driver for the protocol interface.
* The Extras piece contains recommended code for a full-feature implementation including a replacement for the VarLock protocol that enables existing code to continue functioning as-is. It also contains unit and integration tests. And as a bonus, it has a Rust implementation of the core business logic for Variable Policy.

The code can be found in the following two branches:

A convenient way to see all the changes in one place is to look at a comparison:

There’s additional documentation in the PPT and DOC files in the core branch:
https://github.com/corthon/edk2/blob/personal/brbarkel/var_policy_rfc_core/RFC%20VariablePolicy%20Proposal%20Presentation.pptx https://github.com/corthon/edk2/blob/personal/brbarkel/var_policy_rfc_core/RFC%20VariablePolicy%20Whitepaper.docx
(You’d need to download those to view.)

My ultimate intention for this is to submit it as a series of patches for acceptance into EDK2 as a replacement for VarLock. For now, I’m just looking for initial feedback on any broad changes that might be needed to get this into shape for more detailed code review on the devel list.


- Bret

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