[Feature]: Provide a simple component that demonstrates common C module functionality

[makubacki]

Feature Overview

Ideally new Rust code should be written as components. Most code can be but may still need to install global structures like protocols or manipulate global stores like the PCD database. A simple component should demonstrate how to do these actions, so it is available as a reference to new component writers that also need their component to interact with C code.

Solution Overview

Demonstate:

• Install, locate, uninstall protocol
• Hook on and produce a status code
• Get and set a UEFI variable with variable policy
• Get and set a PCD
• Register an event notification callback
• Publish an event notification
• Consume a HOB

Alternatives Considered

No response

Urgency

Low

Are you going to implement the feature request?

I will implement the feature

Do you need maintainer feedback?

No maintainer feedback needed

Anything else?

No response

[rogurr]

Can I request to bump up this task priority?

In a meeting with an OEM today, it was mentioned they are on a path that requires a driver like this to showcase how to transition existing C code to Rust.

Once this is finished, they would like to explore on their own if it is feasible to use the new code in both a UEFI build using the Tiano C based core and a build based on the Patina core.

[Javagedes]

Hi @rogurr I'll write up some different monolithic component examples today to complete this :)

[Javagedes]

@rogurr I wrote some hob usage examples in #586. Most of this issue is currently blocked while #593 completes, as it is going to create a final user interface for these things.

I do want to say that all of this is currently possible by using the StandardRuntimeServices and StandardBootServices types in your component interface, which provides an API very similar to the current C implementation. I could theoretically write examples for of this right now. However, I would just re-write it once #593 completes. Here is a short example:

fn my_component_interface(bs: &StandardBootServices, rt: &StandardRuntimeServices) -> Result<()> {
  // bs.some_boot_services_function(...)?'
  // rt.some_runtime_services_function(...)?;
}

Request	Status
Install, locate, uninstall protocol	On hold for #593
Hook on and produce a status code	On hold for #468
Get and set a UEFI variable with variable policy	On hold for #593
Get and set a PCD	PCDs not supported. Most PCD types are statically compiled via the EDKII build system on a per-module basis.
Register an event notification callback	On hold for #593
Publish an event notification	On hold for #593
Consume a HOB	Completed in #586

[rogurr]

Copy of comment from #593

This enhancement is marked with urgency:medium and is blocked by #593 that is marked urgency:low. Can we proceed with this assuming the RFC is valid?