IPMI Sensor Name limitation of 16 bytes

[Rohit Pai]

Hello,



In our current system we use both Redfish and IPMI for reading sensor values from the BMC.

The sensors are populated over dbus by different bmc internal components and aggregated by bmcweb and ipmid stacks.

The name of the dbus sensor is picked from the dbus object path.

In our system some of the sensor names are very long and have a common platform (or associated entity prefix) which is common for sensor belonging to an entity (parent chassis).



Redfish has no limitation on name of the sensor however ipmid/ipmi tools will only consider the first 16 bytes of the sensor name.

The limitation of IPMI is coming from the spec and the length is restricted to 16 bytes.

[cid:image001.png at 01D981F8.F632D7E0]


So when we query sensor list from over many sensors names appear as same/duplicate entries because many of them have same first 16 chars.
Example showing the issue.

IPMI ------------------------------------------------------------------------------------------------------------------------------------------

FREQ_MEMCNTL_MEM | 0xff              | ok

FREQ_MEMCNTL_MEM | 0xff              | ok

FREQ_MEMCNTL_MEM | 0xff              | ok

FREQ_MEMCNTL_MEM | 0xff              | ok



Redfish -----------------------------------------------------------------------------------------------------------------------------------------

/redfish/v1/Chassis/CG1_Module_PG530_1: FREQ_MEMCNTL_MEM_00_00_176_1

/redfish/v1/Chassis/CG1_Module_PG530_2: FREQ_MEMCNTL_MEM_00_01_4272_1

/redfish/v1/Chassis/CG1_Module_PG530_3: FREQ_MEMCNTL_MEM_00_02_8368_1

/redfish/v1/Chassis/CG1_Module_PG530_4: FREQ_MEMCNTL_MEM_00_03_12464_1

Since there is nothing much we can do about IPMI spec and we also don't want impose limitation of 16 bytes on redfish, I was thinking of adding some sort of auto short name conversion in ipmid to avoid names coming as duplicates.
Would like to receive feedback about this solution and any alternative that may exist to solve this problem. Any pointers on existing patch also would be helpful.

Thanks
Rohit PAI
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