From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Abeni <pabeni@redhat.com>
Subject: Re: [PATCH] IB/ipoib: move back the IB LL address into the hard
 header
Date: Tue, 11 Oct 2016 19:37:32 +0200
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         <20161011173216.GA16892@obsidianresearch.com>
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Cc: linux-rdma@vger.kernel.org, Doug Ledford <dledford@redhat.com>,
        Sean Hefty <sean.hefty@intel.com>,
        Hal Rosenstock <hal.rosenstock@gmail.com>,
        netdev@vger.kernel.org
To: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
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On Tue, 2016-10-11 at 11:32 -0600, Jason Gunthorpe wrote:
> On Tue, Oct 11, 2016 at 07:15:44PM +0200, Paolo Abeni wrote:
> 
> > Also the connected mode maximum mtu is reduced by 16 bytes to
> > cope with the increased hard header len.
> 
> Changing the MTU is going to cause annoying interop problems, can you
> avoid this?

I don't like changing the maximum MTU value, too, but I was unable to
find an alternative solution. The PMTU detection should protect against
such issues.