[ofa-general] [PATCH] IB/ipath - don't allow the QP path MTU to be set higher than port MTU

[Ralph Campbell]

On Tue, 2008-08-12 at 11:40 -0700, Roland Dreier wrote:
> > This patch fixes the problem by returning an error when attempting
>  > to set the QP path MTU greater than the port MTU.
> 
> I don't believe this is correct according to the IB spec -- modify QP is
> supposed to return an error only when the requested MTU is bigger than
> the MTUcap of the port.  Even if we do have this patch, it seems there
> could still be trouble if an intermediate hop has a smaller MTU.
> 
> Why is Open MPI trying to set a path MTU bigger than what the fabric
> actually supports?

Because at one point it didn't check the portinfo, it only relied on the
config file. I did send email about this some time ago so it may be
fixed in newer versions.