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

[Bing Zhao]

Hi,

> -----Original Message-----
> From: Thomas Monjalon <thomas at monjalon.net>
> Sent: Thursday, May 13, 2021 12:04 AM
> To: Bing Zhao <bingz at nvidia.com>; Slava Ovsiienko
> <viacheslavo at nvidia.com>
> Cc: 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
> 
> External email: Use caution opening links or attachments
> 
> 
> 12/05/2021 17:48, 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.
> 
> OK this is what I thought, but it is not clear in the commit message.
> We could think it is the user switching a queue :) Please reword by
> comparing Verbs and DevX without saying "switch".
> 

Thanks you all for your comments. Patch v2 was sent.

> 
> > From: Thomas Monjalon <thomas at monjalon.net>
> > > 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.
> 
> 

BR. Bing