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From: Jakub Kicinski <jakub.kicinski@netronome.com>
To: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>, Parav Pandit <parav@mellanox.com>,
	Jiri Pirko <jiri@resnulli.us>, David M <david.m.ertman@intel.com>,
	"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Saeed Mahameed <saeedm@mellanox.com>,
	"kwankhede@nvidia.com" <kwankhede@nvidia.com>,
	"leon@kernel.org" <leon@kernel.org>,
	"cohuck@redhat.com" <cohuck@redhat.com>,
	Jiri Pirko <jiri@mellanox.com>,
	"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
	Or Gerlitz <gerlitz.or@gmail.com>
Subject: Re: [PATCH net-next 00/19] Mellanox, mlx5 sub function support
Date: Sun, 10 Nov 2019 19:46:01 -0800
Message-ID: <20191110194601.0d6ed1a0@cakuba> (raw)
In-Reply-To: <20191110091855.GE1435668@kroah.com>

On Sun, 10 Nov 2019 10:18:55 +0100, gregkh@linuxfoundation.org wrote:
> > What I'm missing is why is it so bad to have a driver register to
> > multiple subsystems.  
> 
> Because these PCI devices seem to do "different" things all in one PCI
> resource set.  Blame the hardware designers :)

See below, I don't think you can blame the HW designers in this
particular case :)

> > For the nfp I think the _real_ reason to have a bus was that it
> > was expected to have some out-of-tree modules bind to it. Something 
> > I would not encourage :)  
> 
> That's not ok, and I agree with you.
> 
> But there seems to be some more complex PCI devices that do lots of
> different things all at once.  Kind of like a PCI device that wants to
> be both a keyboard and a storage device at the same time (i.e. a button
> on a disk drive...)

The keyboard which is also a storage device may be a clear cut case
where multiple devices were integrated into one bus endpoint.

The case with these advanced networking adapters is a little different
in that they are one HW device which has oodles of FW implementing
clients or acceleration for various networking protocols.

The nice thing about having a fake bus is you can load out-of-tree
drivers to operate extra protocols quite cleanly.

I'm not saying that's what the code in question is doing, I'm saying 
I'd personally like to understand the motivation more clearly before
every networking driver out there starts spawning buses. The only
argument I've heard so far for the separate devices is reloading subset
of the drivers, which I'd rate as moderately convincing.

  reply index

Thread overview: 132+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-07 16:04 Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 01/19] net/mlx5: E-switch, Move devlink port close to eswitch port Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 02/19] net/mlx5: E-Switch, Add SF vport, vport-rep support Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 03/19] net/mlx5: Introduce SF table framework Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 04/19] net/mlx5: Introduce SF life cycle APIs to allocate/free Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 05/19] net/mlx5: E-Switch, Enable/disable SF's vport during SF life cycle Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 06/19] net/mlx5: Add support for mediated devices in switchdev mode Parav Pandit
2019-11-08 10:32     ` Jiri Pirko
2019-11-08 16:03       ` Parav Pandit
2019-11-08 16:22         ` Jiri Pirko
2019-11-08 16:29           ` Parav Pandit
2019-11-08 18:01             ` Jiri Pirko
2019-11-08 18:04             ` Jiri Pirko
2019-11-08 18:21               ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 07/19] vfio/mdev: Introduce sha1 based mdev alias Parav Pandit
2019-11-08 11:04     ` Jiri Pirko
2019-11-08 15:59       ` Parav Pandit
2019-11-08 16:28         ` Jiri Pirko
2019-11-08 11:10     ` Cornelia Huck
2019-11-08 16:03       ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 08/19] vfio/mdev: Make mdev alias unique among all mdevs Parav Pandit
2019-11-08 10:49     ` Jiri Pirko
2019-11-08 15:13       ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 09/19] vfio/mdev: Expose mdev alias in sysfs tree Parav Pandit
2019-11-08 13:22     ` Jiri Pirko
2019-11-08 18:03       ` Alex Williamson
2019-11-08 18:16         ` Jiri Pirko
2019-11-07 16:08   ` [PATCH net-next 10/19] vfio/mdev: Introduce an API mdev_alias Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 11/19] vfio/mdev: Improvise mdev life cycle and parent removal scheme Parav Pandit
2019-11-08 13:01     ` Cornelia Huck
2019-11-08 16:12       ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 12/19] devlink: Introduce mdev port flavour Parav Pandit
2019-11-07 20:38     ` Jakub Kicinski
2019-11-07 21:03       ` Parav Pandit
2019-11-08  1:17         ` Jakub Kicinski
2019-11-08  1:44           ` Parav Pandit
2019-11-08  2:20             ` Jakub Kicinski
2019-11-08  2:31               ` Parav Pandit
2019-11-08  9:46                 ` Jiri Pirko
2019-11-08 15:45                   ` Parav Pandit
2019-11-08 16:31                     ` Jiri Pirko
2019-11-08 16:43                       ` Parav Pandit
2019-11-08 18:11                         ` Jiri Pirko
2019-11-08 18:23                           ` Parav Pandit
2019-11-08 18:34                             ` Jiri Pirko
2019-11-08 18:56                               ` Parav Pandit
2019-11-08  9:30               ` Jiri Pirko
2019-11-08 15:41                 ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 13/19] net/mlx5: Register SF devlink port Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 14/19] net/mlx5: Share irqs between SFs and parent PCI device Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 15/19] net/mlx5: Add load/unload routines for SF driver binding Parav Pandit
2019-11-08  9:48     ` Jiri Pirko
2019-11-08 11:13       ` Jiri Pirko
2019-11-07 16:08   ` [PATCH net-next 16/19] net/mlx5: Implement dma ops and params for mediated device Parav Pandit
2019-11-07 20:42     ` Jakub Kicinski
2019-11-07 21:30       ` Parav Pandit
2019-11-08  1:16         ` Jakub Kicinski
2019-11-08  6:37     ` Christoph Hellwig
2019-11-08 15:29       ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 17/19] net/mlx5: Add mdev driver to bind to mdev devices Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 18/19] Documentation: net: mlx5: Add mdev usage documentation Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 19/19] mtty: Optionally support mtty alias Parav Pandit
2019-11-08  6:26     ` Leon Romanovsky
2019-11-08 10:45     ` Jiri Pirko
2019-11-08 15:08       ` Parav Pandit
2019-11-08 15:15         ` Jiri Pirko
2019-11-08 13:46     ` Cornelia Huck
2019-11-08 15:10       ` Parav Pandit
2019-11-08 15:28         ` Cornelia Huck
2019-11-08 15:30           ` Parav Pandit
2019-11-08 17:54             ` Alex Williamson
2019-11-08  9:51   ` [PATCH net-next 01/19] net/mlx5: E-switch, Move devlink port close to eswitch port Jiri Pirko
2019-11-08 15:50     ` Parav Pandit
2019-11-07 17:03 ` [PATCH net-next 00/19] Mellanox, mlx5 sub function support Leon Romanovsky
2019-11-07 20:10   ` Parav Pandit
2019-11-08  6:20     ` Leon Romanovsky
2019-11-08 15:01       ` Parav Pandit
2019-11-07 20:32 ` Jakub Kicinski
2019-11-07 20:52   ` Parav Pandit
2019-11-08  1:16     ` Jakub Kicinski
2019-11-08  1:49       ` Parav Pandit
2019-11-08  2:12         ` Jakub Kicinski
2019-11-08 12:12   ` Jiri Pirko
2019-11-08 14:40     ` Jason Gunthorpe
2019-11-08 15:40       ` Parav Pandit
2019-11-08 19:12         ` Jakub Kicinski
2019-11-08 20:12           ` Jason Gunthorpe
2019-11-08 20:20             ` Parav Pandit
2019-11-08 20:32               ` Jason Gunthorpe
2019-11-08 20:52                 ` gregkh
2019-11-08 20:34             ` Alex Williamson
2019-11-08 21:05               ` Jason Gunthorpe
2019-11-08 21:19                 ` gregkh
2019-11-08 21:52                 ` Alex Williamson
2019-11-08 22:48                   ` Parav Pandit
2019-11-09  0:57                     ` Jason Gunthorpe
2019-11-09 17:41                       ` Jakub Kicinski
2019-11-10 19:04                         ` Jason Gunthorpe
2019-11-10 19:48                       ` Parav Pandit
2019-11-11 14:17                         ` Jiri Pirko
2019-11-11 14:58                           ` Parav Pandit
2019-11-11 15:06                             ` Jiri Pirko
2019-11-19  4:51                               ` Parav Pandit
2019-11-09  0:12                   ` Jason Gunthorpe
2019-11-09  0:45                     ` Parav Pandit
2019-11-11  2:19                 ` Jason Wang
2019-11-08 21:45             ` Jakub Kicinski
2019-11-09  0:44               ` Jason Gunthorpe
2019-11-09  8:46                 ` gregkh
2019-11-09 11:18                   ` Jiri Pirko
2019-11-09 17:28                     ` Jakub Kicinski
2019-11-10  9:16                     ` gregkh
2019-11-09 17:27                 ` Jakub Kicinski
2019-11-10  9:18                   ` gregkh
2019-11-11  3:46                     ` Jakub Kicinski [this message]
2019-11-11  5:18                       ` Parav Pandit
2019-11-11 13:30                       ` Jiri Pirko
2019-11-11 14:14                         ` gregkh
2019-11-11 14:37                           ` Jiri Pirko
2019-11-10 19:37                   ` Jason Gunthorpe
2019-11-11  3:57                     ` Jakub Kicinski
2019-11-08 16:06     ` Parav Pandit
2019-11-08 19:06     ` Jakub Kicinski
2019-11-08 19:34       ` Parav Pandit
2019-11-08 19:48         ` Jakub Kicinski
2019-11-08 19:41       ` Jiri Pirko
2019-11-08 20:40         ` Parav Pandit
2019-11-08 21:21         ` Jakub Kicinski
2019-11-08 21:39           ` Jiri Pirko
2019-11-08 21:51             ` Jakub Kicinski
2019-11-08 22:21               ` Jiri Pirko
2019-11-07 23:57 ` David Miller

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