Read-Only IPMI sensors

Read-Only IPMI sensors

[Adriana Kobylak]

There are a couple IPMI sensors that are not yet included in the 
data-driven design of IPMI because they're intended to be read-only 
(example: https://github.com/openbmc/openbmc/issues/2154).

Some options to implement these:

1. Add support in sdbusplus for read-only properties and map these 
sensors to a read-only d-bus property.

2. Have a (json?) file with the sensor settings and have IPMI and any 
other interested apps read the file directly to retrieve the sensor 
values.

3. Add read-only sensors to a d-bus object and override the "setter" 
function to be a no-op to prevent the value from being modified.

4. Combination of above / other options.

Thoughts?

Re: Read-Only IPMI sensors

[James Feist]

On 08/13/2018 11:33 AM, Adriana Kobylak wrote:
> There are a couple IPMI sensors that are not yet included in the 
> data-driven design of IPMI because they're intended to be read-only 
> (example: https://github.com/openbmc/openbmc/issues/2154).
> 
> Some options to implement these:
> 
> 1. Add support in sdbusplus for read-only properties and map these 
> sensors to a read-only d-bus property.
> 

sdbusplus-asio already has support for read-only properties that you 
might be interested in using / duplicating: 
https://github.com/openbmc/sdbusplus/blob/master/sdbusplus/asio/object_server.hpp#L123 



> 2. Have a (json?) file with the sensor settings and have IPMI and any 
> other interested apps read the file directly to retrieve the sensor values.
> 
> 3. Add read-only sensors to a d-bus object and override the "setter" 
> function to be a no-op to prevent the value from being modified.
> 
> 4. Combination of above / other options.
> 
> Thoughts?
> 

Re: Read-Only IPMI sensors

[Emily Shaffer]

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host-ipmid also already supports read-only, in fact, adding writable
support was a pretty big work item last year. When you say data-driven
design do you mean the automatic discovery? I guess I'm a little confused
as to what exactly is missing for you.

On Mon, Aug 13, 2018 at 11:32 AM James Feist <james.feist@linux.intel.com>
wrote:

> On 08/13/2018 11:33 AM, Adriana Kobylak wrote:
> > There are a couple IPMI sensors that are not yet included in the
> > data-driven design of IPMI because they're intended to be read-only
> > (example: https://github.com/openbmc/openbmc/issues/2154).
> >
> > Some options to implement these:
> >
> > 1. Add support in sdbusplus for read-only properties and map these
> > sensors to a read-only d-bus property.
> >
>
> sdbusplus-asio already has support for read-only properties that you
> might be interested in using / duplicating:
>
> https://github.com/openbmc/sdbusplus/blob/master/sdbusplus/asio/object_server.hpp#L123
>
>
>
> > 2. Have a (json?) file with the sensor settings and have IPMI and any
> > other interested apps read the file directly to retrieve the sensor
> values.
> >
> > 3. Add read-only sensors to a d-bus object and override the "setter"
> > function to be a no-op to prevent the value from being modified.
> >
> > 4. Combination of above / other options.
> >
> > Thoughts?
> >
>

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Re: Read-Only IPMI sensors

[Adriana Kobylak]

On 2018-08-13 19:03, Emily Shaffer wrote:
> host-ipmid also already supports read-only, in fact, adding writable
> support was a pretty big work item last year. When you say data-driven
> design do you mean the automatic discovery? I guess I'm a little
> confused as to what exactly is missing for you.
> 

Yeah, by data-driven I mean the 
phosphor-ipmi-sensor-inventory%/config.yaml files in the openbmc repo 
where a sensor is matched to a D-Bus object. For example if we create a 
property under the Settings D-Bus object for the derating factor sensor, 
and add this object to the ipmi config.yaml file, a Set Sensor would be 
able to change its value, unless the host-ipmid read-only support 
prevents this. What is the read-only support in ipmi?

> On Mon, Aug 13, 2018 at 11:32 AM James Feist
> <james.feist@linux.intel.com> wrote:
> 
>> sdbusplus-asio already has support for read-only properties that
>> you
>> might be interested in using / duplicating:
>> 
> https://github.com/openbmc/sdbusplus/blob/master/sdbusplus/asio/object_server.hpp#L123
>> [2]
>> 

Thanks, will take a look, since we want read-only properties in 
sdbusplus regardless if they'll be used by ipmi.