I see a problem here.  If a node receives an SMInfo MAD (which is SMI -- 
LID-Route or Direct-Route classes), it would look bizarre to indicate that an 
entire SMI class is not supported, when fact OpenSM is simply not answering a 
"get" on the SMInfo **attribute** .  In this case, #3 is correct (and #1 is NOT 
correct -- the HCA's SMA would still support SMI mads!).

In other cases, where an entire class is not supported (e.g., dev_mgt or SNMP), 
we can still probably return #3, since the attributes tend not to overlap 
between classes (i.e., each class has a mostly unique set of attributes).  
Since it would be a nightmare to differentiate between returning #1 and #3 (if 
this is at all possible -- I believe that in real time it is impossible to tell 
if an entire class has just gone missing (or was never supported), or just the 
specific attribute, such as SM_INFO, for a given class), I suggest we return #3.

-Jack

-----Original Message-----
From: Jason Gunthorpe [mailto:[email protected]]
Sent: Wednesday, January 18, 2012 8:57 PM
To: Hefty, Sean
Cc: Roland Dreier; Swapna Thete; Or Gerlitz; [email protected]; Jack 
Morgenstein
Subject: Re: [PATCH 2/2] IB/mad: Return unsupported for MADs as appropriate

On Wed, Jan 18, 2012 at 05:20:13PM +0000, Hefty, Sean wrote:
> > Surely we should be picking the response status based on the IB spec
> > rather than on the error message that some arbitrary tool prints?
>
> agreed - these are the basic choices:
>
> Code for invalid field
> 0 - no invalid fields
> 1 - Bad version. Either the base version, or the class version, or the
> combination of the two is not supported.
> 2 - The method specified is not supported
> 3 - The method/attribute combination is not supported
>
> none of which seem that great...  IMO, unsupported class version seems
> as good as any.

Figure 169 specifies the validation flow. 1 is the correct reply for 
'Management class is not supported on this port'.

Jason
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