[openib-general] [PATCH] [CM] 1/6 core kernel changes to bind cm_id's to a device

[Sean Hefty]

Roland Dreier wrote:
> Now that cm_id's are per-IB-device, does it make sense to have the
> userspace CM create a charcter node for each IB device?  It seems that
> might simplify the interface.

I've modified the patch to have the uCM create a character node for each IB device.

> uverbs handles up to 32 IB devices with minors 192...223, so using the
> minors 224...255 for 32 ucm devices would make sense.  Unfortunately
> uat is using minor 254, so we would have to do some rejiggering.  I
> guess minor numbers shouldn't be driving this -- we should just pick
> the right interface, whatever it is.

I did go with base minor 224, requiring that uat move its minor.

For the userspace portion, I'm still trying to decide what the correct API 
should be.  I'd like to avoid apps from having to call something like 
ib_cm_get_devices(), which would mirror the verbs call.  I was thinking of 
having ib_cm_create_id() still take a struct ibv_context* as input, opening the 
corresponding CM node, and managing that internally.  Thoughts?

- Sean