Re: [RFC] libibverbs IB device hotplug support

[Alex Rosenbaum <rosenbaumalex-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Wed, Mar 1, 2017 at 2:10 AM, ira.weiny <ira.weiny-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:
> After the call it occurred to me that we may be missing a bigger picture with
> this discussion.  In the past we have discussed in the past what exactly a
> "struct ib_device" is within the context of the kernel.
>
> Should we also consider "port hotplug"?
>
> For example what happens if a Mellanox port is unplugged from an IB port and
> plugged into an Ethernet port?  Is that considered a "device" hot plug?

Yes, this fis a 'device' hotplug.
Reconfiguring a ConnectX3 port from one link layer to another requires
full device plugout & plugin. And this needs to be done by the sys
admin.


> What happens if this is a dual port device and only one of the 2 IB ports are
> changed?  So many things like AH, Path Records, etc are tied to the "device"
> but really they should be tied to the port.

The newer ConnectX4 (and forward) devices expose a pci function per
port, so reconfiguring a port link layer will hotplug only that pci
function.

Alex
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