[PATCH 0/6] Ancillary bus implementation and SOF multi-client support

[Parav Pandit]

> From: gregkh at linuxfoundation.org <gregkh at linuxfoundation.org>
> Sent: Thursday, October 1, 2020 6:25 PM
> 
> On Thu, Oct 01, 2020 at 09:49:00AM -0300, Jason Gunthorpe wrote:
> > On Thu, Oct 01, 2020 at 12:59:25PM +0200, gregkh at linuxfoundation.org
> wrote:
> > > We don't add infrastructure without users.  And the normal rule of
> > > thumb of "if we have 3 users, then it is a semi-sane api" really applies
> here.
> >
> > Based on recent discussions I'm expecting:
> >  - Intel SOF
> >  - New Intel RDMA driver
> >  - mlx5 RDMA driver conversion
> >  - mlx4 RDMA driver conversion
> >  - mlx5 subdevice feature for netdev
> >  - Intel IDXD vfio-mdev
> >  - Habana Labs Gaudi netdev driver
> >
> > Will use this in the short term.
> >
> > I would like, but don't expect too see, the other RDMA RoCE drivers
> > converted - cxgb3/4, i40iw, hns, ocrdma, and qedr. It solves an
> > annoying module loading problem we have.
> >
> > We've seen the New Intel RDMA driver many months ago, if patch 1 is
> > going to stay the same we should post some of the mlx items next week.
> >
> > It is hard to co-ordinate all of this already, having some general
> > agreement that there is nothing fundamentally objectionable about
> > ancillary bus will help alot.
> 
> I agree, but with just one user (in a very odd way I do have to say, more on
> that on the review of that specific patch), it's hard to judge if this is useful are
> not, right?
> 

As Jason mentioned above, mlx5 subdevice feature, I like to provide more context before posting the patches.

I have rebased and tested mlx5 subfunction devices for netdev to use ancillary device as per the RFC posted at [1].
These subdevices are created dynamically on user request. Typically then are in range of hundreds.
Please grep for virtbus to see its intended use in [1].

To refresh the memory, before working on the RFC [1], mlx5 subfunction use is also discussed further with Greg at [2].
Recently I further discussed ancillary bus (virtbus) intended use for mlx5 subfunction with netdev community at [3] and summarized in [4] , jump to last slide 22.

mlx5 series is bit long and waiting for mainly ancillary bus to be available apart from some internal reviews to finish.

[1] https://lore.kernel.org/netdev/20200519092258.GF4655@nanopsycho/
[2] https://patchwork.kernel.org/patch/11280547/#23056985
[3] https://netdevconf.info/0x14/pub/papers/45/0x14-paper45-talk-paper.pdf
[4] https://netdevconf.info/0x14/pub/slides/45/sf_mgmt_using_devlink_netdevconf_0x14.pdf

> So, what happened to at least the Intel SOF driver usage?  That was the
> original user of this bus (before it was renamed), surely that patchset should
> be floating around somewhere in Intel, right?
> 
> thanks,
> 
> greg k-h