[ofa-general] Receiving 24-byte remnant header on bad umad_recv?

[Joseph L Greathouse]

>> I am building a program that sometimes sends MADs from device A to
>> device B, and device B should (by design) silently ignore these
>> packets.,
>>
>> Device A is using OFED 1.3.1's libibumad-1.1.7, and I am sending
>> these MADs using a regular umad_send() method. When B responds,
>> the subsequent umad_recv() works just fine.  However, when B is
>> supposed to silently ignores the MAD, device A's subsequent
>> umad_recv() receives a strange  packet rather than timing out.
>> It receives a 24-byte packet that looks like a MAD Header. All of
>> its fields except for TID are the same as the original send's MAD
>> Header.
>>
>This is expected... the small packet is showing that device A's
>request is timing out (and you should see the status field in the
>packet showing a timeout error -- I forget the exact details but you
>can look at the user_mad.c source in the kernel to see what happens
>in this case).

Aha!  That makes a lot more sense now.  Thank you.

-Joe Greathouse