Original suggestion sent to mailing list on 11th April 2019:
I think that there should be a single entry point for any platform specific service request to the platform/ directory and each platform should/could list the specific features it supports. Then the specific function type would be encoded in an invec to the service request.
But I think a more detailed design proposal is needed with enough room for discussion before committing to a new pattern, and I'd prefer to avoid introducing platform dependencies in the services/ folder. That folder should ideally just have an indirection across HAL to a platform-specific service request arbiter.
Update on 25th April 2019:
I'm close to submitting a change on review containing a proposal. Sorry for the long delay.