[dpdk-stable] [PATCH] net/mlx5: fix loopback for DV queue

[Slava Ovsiienko]

Hi, Thomas

> How do we switch?

Historically mlx5 created Queues and other HW objects with Verbs.
Now we are migrating ("switched") to DevX - queues are being created with DevX calls.
If there is no E-Switch - the new DevX approach is engaged,
for E-Switch configurations we still use Verbs.

With best regards,
Slava

> -----Original Message-----
> From: Thomas Monjalon <thomas at monjalon.net>
> Sent: Wednesday, May 12, 2021 18:31
> To: Bing Zhao <bingz at nvidia.com>
> Cc: Slava Ovsiienko <viacheslavo at nvidia.com>; Matan Azrad
> <matan at nvidia.com>; dev at dpdk.org; Ori Kam <orika at nvidia.com>; Raslan
> Darawsheh <rasland at nvidia.com>; stable at dpdk.org
> Subject: Re: [PATCH] net/mlx5: fix loopback for DV queue
> 
> 12/05/2021 16:51, Bing Zhao:
> > From: Thomas Monjalon <thomas at monjalon.net>
> > > 12/05/2021 16:36, Bing Zhao:
> > > > When switching to the Devx interface, the kernel driver behavior
> > > may
> > >
> > > What do you mean by "switching"?
> >
> > I mean when changing the Rxq from Verbs API to Devx API.
> 
> 
> > > > be different from using Verbs. The Tx loopback cannot work
> > > properly
> > > > even if the Tx and Rx queues are configured with loopback
> > > attribute.
> > > > To support self loopback for Tx, a Verbs dummy queue pair needs to
> > > be
> > > > created to trigger the kernel to enable the loopback.
> > > >
> > > > This is only required when TIR is created for Rx and loopback is
> > > > needed. Only CQ and QP are needed for this case, no WQ(RQ) needs
> > > to be
> > > > created.
> 
>