Entity Manager questions

Srinivasan, Usha usha.srinivasan at cornelisnetworks.com
Wed May 5 07:06:15 AEST 2021

I'm working on my first full OpenBMC project.   I watched James' Entity Manager presentation on YouTube and it explained quite a lot.  However, I still have questions that I'm hoping someone can answer.

1) In my setup, FruDevice fails looking for /etc/fru/baseboard.fru.bin.
Q:  I am guessing that a baseboard eeprom is one at i2c bus 0.  What if your platform doesn't have such an eeprom?

Q: Who is responsible for creating the /etc/fru/baseboard.fru.bin file and what are its contents?

2) Q: My understanding is when using FruDevice with EntityManager, during platform setup/manufacturing all the FRU eeproms will have to be initialized with data formatted as described by this Intel document.  Is this correct?
Q:  Is there a python script and/or application that can be used to initialize an eeprom using textual data provided as input?

3) Q: My understand is this: by using Entity Manager & JSON configuration files, I no longer need these kinds of YAML files:

4) Q: However, I assume I will still need to create fans, gpios, leds, power & sensor conf files like these. Is this correct?
Q: I ask the previous question because, I see these errors. What am I missing?
Failed to introspect object / of service xyz.openbmc_project.Hwmon.external: Unknown object '/'.
Failed to introspect object / of service xyz.openbmc_project.State.FanCtrl: Unknown object '/'.
5) Q: I see a createHwSensor field in devices.hpp in Entity Manager but I was not able to figure out what effect it has.  For example, TMP421 has createHwSensor set to true while an eeprom doesn't.

6) Q: Overall, all I am monitoring on my platform are power supplies, fans, temp sensors, voltage regulators.  If the drivers for the devices on my platform are already exist in linux and the devices adhere to standards such as PMBus, I am assuming there will be little need to develop new drivers and/or monitoring daemons.  Is this correct?  I ask this question because in a very much older version of OpenBmc the vendor developed their own fand to monitor temperatures & adjust fan speeds.



Usha Srinivasan
Embedded Software Engineer
Cornelis Networks
1500 Liberty Ridge Dr
Chesterbrook, PA, 19087
610-703-8475 (cell)

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