Re: [Suit] Propose to add suit-uninstall in Multiple Trust Domains draft

[Dave Thaler <[e-mail]>]

Ken Takayama writes:
> # Proposal
> Add suit-uninstall to the Multiple Trust Domains document
> because it is useful functionality when updating depending components in some situations.
...
> ## Issue
> The library-a is no more required and should be uninstalled,
> but how to uninstall it when updating the application?

>From a TEEP perspective, I think this is important to say how to do.  I run into this issue in my TEEP implementation too.

The TEEP protocol used to have a field in the Update message (in addition to any SUIT manifests) that identified which components to remove.  Recently the TEEP protocol was updated to just list manifests, under an assumption that the manifest would contain deletion instructions. 

The TAM (an update server) sends manifests or references to them, to a TEEP Agent (a device on which to install/update/uninstall components with SUIT manifests).
So to do a deletion, the TAM needs a way to indicate that without it being the component author.   It could do that by the TAM creating the SUIT manifests themselves, and incrementing the sequence number to do a deletion but that would require generating manifests on the fly rather than having one manifest for all TEEP Agents, some of which might have the component installed and some not.

It could also do it by not using a newer SUIT manifest but having the uninstall directives included in the installation manifest as Ken proposed, in which case the original TEEP mechanism might make sense to put back in.

Dave