netdev - Re: [net-next PATCH 00/15] eth: fbnic: Add network driver for Meta Platforms Host Network Interface

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Date: Mon, 8 Apr 2024 12:50:07 -0700
From: Mina Almasry <almasrymina@...gle.com>
To: Alexander Duyck <alexander.duyck@...il.com>
Cc: Jason Gunthorpe <jgg@...dia.com>, Paolo Abeni <pabeni@...hat.com>, Jakub Kicinski <kuba@...nel.org>, 
	John Fastabend <john.fastabend@...il.com>, Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org, 
	bhelgaas@...gle.com, linux-pci@...r.kernel.org, 
	Alexander Duyck <alexanderduyck@...com>, davem@...emloft.net, Christoph Hellwig <hch@....de>, 
	Eric Dumazet <edumazet@...gle.com>, Willem de Bruijn <willemb@...gle.com>
Subject: Re: [net-next PATCH 00/15] eth: fbnic: Add network driver for Meta
 Platforms Host Network Interface

On Sat, Apr 6, 2024 at 9:05 AM Alexander Duyck
<alexander.duyck@...il.com> wrote:
> > > > You have an unavailable NIC, so we know it is only ever operated with
> > > > Meta's proprietary kernel fork, supporting Meta's proprietary
> > > > userspace software. Where exactly is the open source?
> > >
> > > It depends on your definition of "unavailable". I could argue that for
> > > many most of the Mellanox NICs are also have limited availability as
> > > they aren't exactly easy to get a hold of without paying a hefty
> > > ransom.
> >
> > And GNIC's that run Mina's series are completely unavailable right
> > now. That is still a big different from a temporary issue to a
> > permanent structural intention of the manufacturer.
>
> I'm assuming it is some sort of firmware functionality that is needed
> to enable it? One thing with our design is that the firmware actually
> has minimal functionality. Basically it is the liaison between the
> BMC, Host, and the MAC. Otherwise it has no role to play in the
> control path so when the driver is loaded it is running the show.
>

Sorry, I didn't realize our devmem TCP work was mentioned in this
context. Just jumping in to say, no, this is not the case, devmem TCP
does not require firmware functionality AFAICT. The selftest provided
with the devmem TCP series should work on any driver that:

1. supports header split/flow steering/rss/page pool (I guess this
support may need firmware changes...).

2. supports the new queue configuration ndos:
https://patchwork.kernel.org/project/netdevbpf/patch/20240403002053.2376017-2-almasrymina@google.com/

3. supports the new netmem page_pool APIs:
https://patchwork.kernel.org/project/netdevbpf/patch/20240403002053.2376017-8-almasrymina@google.com/

No firmware changes specific to devmem TCP are needed, AFAICT. All
these are driver changes. I also always publish a full branch with all
the GVE changes so reviewers can check if there is anything too
specific to GVE that we're doing, so far there are been no issues, and
to be honest I can't see anything specific that we do with GVE for
devmem TCP:

https://github.com/mina/linux/commits/tcpdevmem-v7/

In fact, GVE is IMO a relatively feature light driver, and the fact
that GVE can do devmem TCP IMO makes it easier for fancier NICs to
also do devmem TCP.

I'm working with folks interested in extending devmem TCP to their
drivers, and they may follow up with patches after the series is
merged (or before). The only reason I haven't implemented devmem TCP
for multiple different drivers is a logistical one. I don't have
access to hardware that supports all these prerequisite features other
than GVE.

-- 
Thanks,
Mina