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Subject: Re: [PATCH] netpoll: support sending over raw IP interfaces
From: Mark <mark@yotsuba.nl>
In-Reply-To: <20240314113455.152cebc9@kernel.org>
Date: Mon, 18 Mar 2024 12:47:46 +0100
Cc: netdev@vger.kernel.org,
 Hans de Goede <hdegoede@redhat.com>,
 Eric Dumazet <edumazet@google.com>,
 Breno Leitao <leitao@debian.org>,
 Ingo Molnar <mingo@redhat.com>,
 "David S. Miller" <davem@davemloft.net>,
 Paolo Abeni <pabeni@redhat.com>,
 linux-kernel@vger.kernel.org
Content-Transfer-Encoding: quoted-printable
Message-Id: <93E237FA-9F0B-48E4-8A89-B9C2619B90A5@yotsuba.nl>
References: <20240313124613.51399-1-mark@yotsuba.nl>
 <20240314113455.152cebc9@kernel.org>
To: Jakub Kicinski <kuba@kernel.org>

Hi Jakub,

> Op 14 mrt 6 Reiwa, om 19:34 heeft Jakub Kicinski <kuba@kernel.org> het =
volgende geschreven:
>=20
> On Wed, 13 Mar 2024 13:46:13 +0100 Mark Cilissen wrote:
>> Currently, netpoll only supports interfaces with an =
ethernet-compatible
>> link layer. Certain interfaces like SLIP do not have a link layer
>> on the network interface level at all and expect raw IP packets,
>> and could benefit from being supported by netpoll.
>>=20
>> This commit adds support for such interfaces by using the network =
device's
>> `hard_header_len` field as an indication that no link layer is =
present.
>> If that is the case we simply skip adding the ethernet header, =
causing
>> a raw IP packet to be sent over the interface. This has been =
confirmed
>> to add netconsole support to at least SLIP and WireGuard interfaces.
>=20
> Would be great if this could come with a simple selftest under
> tools/testing/selftests/net. Preferably using some simple tunnel
> device, rather than wg to limit tooling dependencies ;)

Yes, that makes a lot of sense. I wrote a selftest that tests netconsole
using IPIP and GRE tunnels, and they too seem to work correctly and pass =
(and
more importantly, fail without the patch ;-). Would you prefer me to =
submit
a v2 with that test now, or when net-next reopens in a week?

Thanks and regards,
Mark=