Add an Asynchronous Process Loader

[bradjc]

Add an Asynchronous Process Loader

[alevy]

I agree with this proposal broadly, but just a nit:

This is somewhat historical: simple process loading only requires parsing flash, creating a Process struct, and iterating through flash. No split-phase operations are required and a synchronous function works fine.

I don't think this is purely "historical," in particular the most widely deployed use-case of Tock only has this exact model. Indeed, there is no credential checking, etc, for each process binary and everything should load before starting (or at least its perfectly fine to block starting to run until everything has loaded).

It is probably worth retaining the ability to do that simple version, even if many use-cases will only ever load things asynchronously.

[lschuermann]

As a side note, one cool new feature this could enable is loading processes from (external) flash into RAM for chips or architectures that do not have XIP flash. I'm not sure whether this is impossible with the current architecture, but it might just be something to consider if we were redesigning these interfaces.

[bradjc]

As a side note, one cool new feature this could enable is loading processes from (external) flash into RAM for chips or architectures that do not have XIP flash. I'm not sure whether this is impossible with the current architecture, but it might just be something to consider if we were redesigning these interfaces.

That would certainly require async, and having a framework for async process loading would make extending to that case much easier.