Processing PLDM FRU information with entity manager

[Brad Bishop]

On Tue, 2020-05-19 at 09:10 +0530, Deepak Kodihalli wrote:

Hi Deepak

> I see there is provision for persistence, but it looks like
> applying the persisted information works only if "D-Bus probes"
> succeed.

This prompted me to take a closer look - as far as I can tell
system.json is for debugging purposes only.  Maybe James could confirm.

Given this we should probably have an application layer other than
entity-manager layer be responsible for maintaining the PLDM FRU
objects on the DBus at the correct time. 

> the BMC will no longer have the raw PLDM FRU information on D-Bus

I think we have to fix this.  It doesn't feel right that the PLDM FRU
DBus objects come and go off the bus as the system is powered on/off.

> How are hierarchical relationships between FRUs supposed to be 
> represented? Is that based on D-Bus pathnames? Or making use of 
> something like the D-Bus Associations interface? Any thoughts on how 
> representing such parent-child relation can be achieved via entity 
> manager configs?

I'm also hoping James or Richard will let us know what their thoughts
are for doing this.

-brad