[PATCH linux dev-4.7 7/8] ipmi: maintain a request expiry list

[Cédric Le Goater]

On 11/04/2016 02:55 AM, Patrick Williams wrote:
> On Thu, Nov 03, 2016 at 07:46:28PM +0100, Cédric Le Goater wrote:
>> On 11/03/2016 07:23 PM, Patrick Williams wrote:
>>> On Thu, Nov 03, 2016 at 11:26:09AM +1100, Cyril Bur wrote:
>>>> On Wed, 2016-10-26 at 08:57 +0200, Cédric Le Goater wrote:
>>>>> Regarding the response expiration handling, the IPMI spec says :
>>>>>
>>>>>    The BMC must not return a given response once the corresponding
>>>>>    Request-to-Response interval has passed. The BMC can ensure this
>>>>>    by maintaining its own internal list of outstanding requests
>>>>> through
>>>>>    the interface. The BMC could age and expire the entries in the
>>>>> list
>>>>>    by expiring the entries at an interval that is somewhat shorter
>>>>> than
>>>>>    the specified Request-to-Response interval....
>>>>>
>>>>> To handle such case, we maintain list of received requests using the
>>>>> seq number of the BT message to identify them. The list is updated
>>>>> each time a request is received and a response is sent. The
>>>>> expiration
>>>>> of the reponses is handled at each updates but also with a timer.
>>>>>
>>>>
>>>> I agree that the BMC kernel is most logical place to do this, at the
>>>> moment btbridged does attempt something similar no?
>>>>
>>>> Should we patch btbridged to not? Should I least remove duplicated
>>>> logic? 
>>>>
>>>
>>> Brendan,
>>>
>>> Are you paying attention to this discussion?  I think you had some
>>> opposition to the kernel doing any additional work in this space because
>>> you wanted to run a non-IPMI protocol over the IPMI bridge.
>>
>> We will then need a new kernel driver for the non-IPMI interface. 
>> This one is for the iBT interface which is IPMI oriented. 
>>
>> I am sure we can find some common points though. Hopefully, the 
>> userspace interface would be the same. For the moment we only
>> have an ioctl for the SMS ATN interrupt but we should be adding
>> some more.
>>
> 
> I believe Brendan was keeping the IPMI protocol but implementing
> different flow control on top of it.  That means, specifically, that
> having the kernel track commands and timeouts would not be what he
> wanted.

ok. I have lost track of this. May be we could start a wiki on 
btbridge to hold all these ideas, development progress, etc. 
Like we have done for qemu and u-boot ?

Thanks,

C.