inferiors and services

["Todor Kondić" <tk.code@protonmail.com>]

Dear guixians,

During the operating system instantiation -- either through `reconfigure`, or various `image` procedures) -- is the only possible way of controlling which version of services and the packages installable by those services to specify a particular commit in the channel config?

Inferiors help isolate a package manifest together with an user-controlled guix commit, so I was wondering if anything such is possible with the system itself (for example, during building of an image). In pseudocode:

(define inferior (inferior-from-channels ...))
(with-inferior inferior (reconfigure (operating-system ...)))

I am almost certain there is some gexp mumbo-jumbo-derivation-of-the-whole-system one can use, but not yet entirely comfortable with them.

T