D-Bus interface to provide data to entity manager
Deepak Kodihalli
dkodihal at linux.vnet.ibm.com
Fri May 29 20:30:12 AEST 2020
On 29/05/20 3:49 pm, Deepak Kodihalli wrote:
> On 29/05/20 2:33 pm, Thomaiyar, Richard Marian wrote:
>>
>> On 5/29/2020 1:01 PM, Deepak Kodihalli wrote:
>>> On 29/05/20 12:47 pm, Thomaiyar, Richard Marian wrote:
>>>>
>>>> On 5/29/2020 10:39 AM, Deepak Kodihalli wrote:
>>>>> On 28/05/20 11:35 pm, Patrick Williams wrote:
>>>>>> On Thu, May 28, 2020 at 10:12:19PM +0530, Thomaiyar, Richard
>>>>>> Marian wrote:
>>>>>>>
>>>>>>> On 5/28/2020 5:54 PM, Deepak Kodihalli wrote:
>>>>>>>> On 28/05/20 5:33 pm, Patrick Williams wrote:
>>>>>>
>>>>>>> Why do we need to have 2 different interfaces to represent the same
>>>>>>> information for FRU-to-inventory transformational (say
>>>>>>> ProductName). This
>>>>>>> will make inventory manager to be updated for every FRU
>>>>>>> producer?. Many of
>>>>>>> the properties are common, and we can form a common interface for
>>>>>>> that, and
>>>>>>> rest can be maintained in it's specific interface. I understand
>>>>>>> that current
>>>>>>> FRU to Entity-manager interface seems to be private, but we must
>>>>>>> make a
>>>>>>> common interface to represent like Product Name, PartNumer,
>>>>>>> Serial Number
>>>>>>> etc. (instead of maintaining it in different interface saying
>>>>>>> IPMI / PLDM
>>>>>>> Source, with different types). How about?
>>>>>
>>>>> Richard, I have concerns with this approach. Like I mentioned in
>>>>> one my earlier emails, and Patrick also alludes to below, if you
>>>>> try to make this common (event if it's for a subset of the
>>>>> properties) then you basically arrive at the existing phosphor
>>>>> Inventory interfaces (eg Inventory.Decorator.Asset).
>>>>>
>>>>> My question in my earlier mail was, if you do such a thing, then
>>>>> why do you even need inventory producers? FruDevice and PLDM could
>>>>> have hosted inventory on their own. If they still rely on the
>>>>> inventory producers (EM and PIM) with this "common interface"
>>>>> approach, then it's basically re-implementation/duplications of the
>>>>> (Inventory.Decorator.Asset like) interface by two processes.
>>>
>>> Richard, what is your thought on the re-implementation/duplication
>>> concern above? I'm not sure if you answered that and I missed.
>> [Richard]: FRU Consumers must be aware about each and every Format
>> specifically, even though it conveys same meaning.
>
> I agree with that, but my question was about FRU producers.
>
>
>>>> [Richard]: Basically FRU information (either IPMI/PLDM) is needed
>>>> for the inventory producers to expose configuration, which FRU will
>>>> not have. Say, based on FRU Product name, either we will expose 4
>>>> temp sensor / 2 (Now along with this one, we need to inform the
>>>> product name through Inventory.Decorator.Asset). Now from Redfish
>>>> point of it, Inventory.Decorator is what it uses. This is what i was
>>>> asking with 2 options in earlier mail (whether to change or stick
>>>> with it (recommended)).
>>>
>>>>>
>>>>> The idea is for apps like FruDevice and PLDM, which are aware of a
>>>>> specific FRU format, to host data in *that* format, to be consumed
>>>>> *solely* by inventory producers (like EM and PIM).
>>>>>
>>>> [Richard]: Yes, but it doesn't need to expose those in that format?
>>>
>>> Why not?
>> [Richard]: What's the advantage in keeping it in that format itself?
>
> The advantage I see is basically what you said on the next line.
>
>> This is used only by EM / PIM, and not by redfish directly right?
>> Where the intelligence must reside in the producer or consumer (With
>> producer, consumers can be in common form)
>
>>>> Say Manufacturer Name, it doesn't mater whether it is coming from
>>>> PLDM FRU / IPMI FRU. Say we have a special handling for a particular
>>>> manufacture / product, then irrespective of inventory producers both
>>>> can handle the same.
>>>
>>> This is what the Inventory.Decorator.Asset interface is for.
>> [Richard]: Yes, That is exposed by EM / PIM in our case. Why EM / PIM
>> must rely on 2 different stuff, for common things is the question here.
>>>
>>>> If we have 2 different interface, then inventory producer may need
>>>> to be aware about both and probe it accordingly.
>>>
>>> No, the "FRU" properties producer needs to be concerned only about
>>> the format it understands.
>>
>> [Richard]: FRU property producer must know the format and produce the
>> interface with data (in common form as much as possible). E.g. IPMI
>> FRU Producer (say xyz.openbmc_project.FruDevice service) will read
>> device A FRU, and expose the Manufacturer name (It can read the EEPROM
>> content and decode it as per the IPMI FRU format, but the data it
>> produces is Manufacturer name). Simiarly PLDM FRU Producer (say
>> xyz.openbmc_project.PLDM.FruDevice service) will read the data using
>> PLDM FRU commands, and expose the Manufacturer name. Now why this 2
>> service need to have 2 different interface(one from
>> Inventory.Source.PLDM & another from Inventory.Source.IPMI, to expose
>> the Manufacturer name. ? Why Entity manager / PIM need to read the
>> same information from 2 different interface and expose it in
>> Inventory.Decorator.Asset. (It can do it with same interface).
>
> What is that interface?
@Richard - to elaborate further - on Gerrit you suggest moving things
like Serial Number and Part Number to Inventory.Decorator.Asset.
However, note that these are already present in
Inventory.Decorator.Asset. Hence the question - why do want FruDevice,
PLDM, EM, PIM to all implement Inventory.Decorator.Asset?
>> What Entity manager / PIM needs to do is using Object Mapper query all
>> the FruDevices (IPMI / PLDM FRU), and accordingly expose the Inventory
>>>> FRU producers code must be written in such a way that for these
>>>> common properties it does the necessary conversion (Say make
>>>> manufacturer as string, irrespective of any format it read through).
>>>> Note: Specific stuff, we need to create a separate interface (as
>>>> phosphor-dbus-interface at present doesn't support dynamic property
>>>> addition/deletion). (Tomorrow, if we have any other proprietary way
>>>> of producing FRU data, we can still work with this approach, with
>>>> less or no change for other layers).
>>>>
>>>>> Also note that (as James pointed out in his email), the IPMI FRU
>>>>> format distinguishes Board/Chassis/Product areas. PLDM FRU format
>>>>> does not. So there are differences. If a new FRU format is
>>>>> introduced, then yes we would expect a new interface to show up
>>>>> under Inventory/Source/<FruFormat>
>>>> [Richard]: Fru producers should do this conversion.
>>>
>>> I'm of the opinion that the inventory producer (like EM and PIM)
>>> should perform this conversion. Consider
>>> https://github.com/openbmc/entity-manager/blob/master/configurations/Intel%20Front%20Panel.json#L55
>>> for example. I don't think it's up to the FruDevice/PLDM kind of apps
>>> to decide that this is actually a Panel. You can design it that way,
>>> but like I said above that means the config knowledge moves into
>>> these apps, which I don't think we should head towards, since then
>>> every FRU producer app needs to do this. This is why we have apps
>>> like EM.
>> [Richard]: Exactly. What we need to make sure is create abstraction
>> between Entity manager and FRU Producers as much as possible. FRU
>> Producer responsibility is to read the FRU in decode the FRU data as
>> per the spec and expose it in common form which Entity-manager / PIM
>> will rely on.
>
> I don't see why the abstraction is necessary. There already is
> abstraction in terms of the phosphor interfaces.
>
>>>> Say Chassis Type (Irrespective of what area it comes from it is
>>>> same). PLDM FRU mostly represents the product as a whole, but
>>>> technically we can point it to all the needed using the Fru Record
>>>> set to the Entity type mapping in the PDR record. Accordingly it
>>>> needs to be exposed.
>>>>>
>>>>>
>>>>>> Yes, I am in favor of common interfaces for this where ever possible.
>>>>>>
>>>>>> Is there someone that knows the existing FruDevice implementation
>>>>>> well
>>>>>> enough that can be included in this work to propose common interfaces
>>>>>> where it is appropriate?
>>>>>>
>>>>>>> Inventory/Source/General/Fru (Maintain common things here Product
>>>>>>> Name.
>>>>>>> This can be used by Inventory manager to advertise it (instead of
>>>>>>> searching
>>>>>>> it in multiple interfaces/properties))
>>>>>>
>>>>>> Minor tweak here of 'Source/Common'? When we have an existing
>>>>>> Inventory
>>>>>> interface for this information should we mimic what is already in
>>>>>> Inventory? At some point are we trying to be too common that we're
>>>>>> effectively reimplementing Inventory instances under a different
>>>>>> name?
>>>>>>
>>>> [Richard]: Yes, currently, FRU to inventory and inventory to upper
>>>> layer is what used. If we want to change it, we need to go with
>>>> differnt option of using FRU to upper layer, but many of existing
>>>> code will require change.
>>>
>>>
>>>> Regards,
>>>>
>>>> Richard
>>>>
>>>
>
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