Discrete Sensors in OpenBMC

[Ed Tanous]

On Tue, Jan 19, 2021 at 6:23 AM Wludzik, Jozef
<jozef.wludzik at linux.intel.com> wrote:
>
> Does anyone use or implement discrete sensor in OpenBMC? Redfish defines
> discrete triggers that use discrete values to detect that threshold is
> crossed and trigger action should be commited. Redfish does not mention
> about discrete sensor/values in other topics/schemes than Telemetry
> (e.g. MetricDefinition, MetricReportDefinition and MetricReport). I am
> asking about it because we are trying to find an example of discrete
> sensor to proceed with DiscreteTriggers implementation (aka Discrete
> thresholds) from Triggers scheme.

A "discrete" sensor is terminology that's only used in IPMI.  The
equivalent in Redfish would be an enum type property, of which there
are many examples.  The most obvious discrete-like sensor that we have
an example of today would be the Systems PowerState parameter, which
changes state based on the power state of the system.

If you're looking to stream events through redfish, generally you
would implement some kind of property, then you would implement a
Resource Changed event that someone could subscribe to from here:
https://redfish.dmtf.org/registries/ResourceEvent.1.0.3.json

We don't have the subscription part implemented yet, but there was
some talk about getting that going.

>
> Ref.:
>
> Redfish Telemetry White Paper -
> https://www.dmtf.org/sites/default/files/standards/documents/DSP2051_1.0.0.pdf
>
> Thanks,
> Jozef
>