Changing Between Infiniband Connected Mode and Datagram Mode at Runtime on FreeBSD 12.2

Hans Petter Selasky hps at
Thu Mar 4 10:14:02 UTC 2021

On 3/4/21 3:49 AM, Foster, Greg wrote:
> Hello FreeBSD IB,
> What is the procedure to change between Infiniband Connected Mode and Datagram Mode
> at runtime on FreeBSD 12.2?
> I've seen different references on the WEB, but the procedure still seems unclear.
> In one reference
> refers to the Linux procedure, which is not applicable on FreeBSD.
> Another reference,, implies the driver must be recompiled
> to change modes.
> Yet another,
> Suggests it can be done at runtime to add a tuneable/sysctl but doesn't specify any details...
> Is the solution to maybe compile the drivers twice, once for CM and once for DM, keeping both around
> and loading the desired one?


For IPoIB there is an option you need to set at compile time for this 
feature to be activated:

sys/conf/options:IPOIB_CM	opt_ofed.h


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