[ofw] RE: [PATCH] umad - add missing item from latest management tree

[Hal Rosenstock]

On Fri, Oct 16, 2009 at 5:29 PM, Hal Rosenstock
<hal.rosenstock at gmail.com> wrote:
> On Fri, Oct 16, 2009 at 12:23 AM, Sean Hefty <sean.hefty at intel.com> wrote:
>>>> Can you explain again why this is needed?
>>>>
>>>> Windows has no restriction on the number of MAD agents, so this
>>>> should be set to something huge, like 4 billion.  If the user is
>>>> assuming that this is a small value, then I think we need to fix that
>>>> code.
>>>
>>>Opensm 3.2.2
>>
>> That doesn't really explain anything.  How is opensm using this value, and what
>> assumptions does it make about its size?
>
> I'm not sure why that define was added to umad.h. I don't see it used
> anywhere within libibumad itself. It is used by the OpenSM umad vendor
> layer to size an array to simplify things there. It's used to track
> the umad registrations in the OpenSM umad vendor layer. 32 is plenty
> as only a few are used but the number could be changed or the scheme
> could also be changed to not have such a limit.

I remember now: The number comes from drivers/infiniband/user_mad.c
where IB_UMAD_MAX_AGENTS = 32 so it's the current Linux limitation on
this. As you said, Windows could be very different in terms of this.

-- Hal

>
> -- Hal
>
>> We should make sure that we have the
>> right fix here.
>>
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>