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Date: Wed, 29 Apr 2026 19:01:50 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Marc Harvey <marcharvey@google.com>
Cc: Saeed Mahameed <saeedm@nvidia.com>, Leon Romanovsky <leon@kernel.org>,
 Tariq Toukan <tariqt@nvidia.com>, Mark Bloch <mbloch@nvidia.com>, Andrew
 Lunn <andrew+netdev@lunn.ch>, "David S. Miller" <davem@davemloft.net>, Eric
 Dumazet <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>,
 netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
 linux-kernel@vger.kernel.org, Kuniyuki Iwashima <kuniyu@google.com>
Subject: Re: [PATCH net-next] net/mlx5: Add MLX5_VXLAN config option
Message-ID: <20260429190150.417b0302@kernel.org>
In-Reply-To: <CANkEMgkBnuRfurKcFEUAZcJcX1XYSnHbBozZGP8DpnKq--tWbw@mail.gmail.com>
References: <20260428-mlx5_vxlan-v1-1-cf666d042618@google.com>
	<20260428184631.40f1f1b7@kernel.org>
	<CANkEMgkBnuRfurKcFEUAZcJcX1XYSnHbBozZGP8DpnKq--tWbw@mail.gmail.com>
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On Wed, 29 Apr 2026 17:46:36 -0700 Marc Harvey wrote:
> On Tue, Apr 28, 2026 at 6:46=E2=80=AFPM Jakub Kicinski <kuba@kernel.org> =
wrote:
> >
> > On Tue, 28 Apr 2026 22:44:34 +0000 Marc Harvey wrote: =20
> > > Currently, there is no way to disable mlx5 vxlan offloading if vxlan
> > > is enabled. We've (possibly) seen some minor udp rr and udp stream
> > > regressions when enabling vxlan, and want a way to disable this
> > > offloading. Also coupling vxlan offloading with vxlan enablement
> > > generally limits the flexability of vxlan setups.
> > >
> > > Add a new config option for mlx5 vxlan offloading specifically, so
> > > that users can use vxlan without automatically opting in to the
> > > offloading.
> > >
> > > To keep the same behavior as before, the new config option is enabled
> > > by default if vxlan is enabled. =20
> >
> > Can we delay init of whatever makes the device slow down until the
> > first vxlan port is registered? A kconfig level optimization of this
> > sort will have rather limited applicability. =20
>=20
> There would still be the problem of wanting to use vxlan without vxlan
> offload. Agree that a kconfig might not be ideal, but it is currently
> guarded by a kconfig that offers no choice to opt out.

Are you aware of NETIF_F_RX_UDP_TUNNEL_PORT ?
I haven't checked it does exactly what we need, but I recall there was=20
a ethtool feature for this..