From: Jakub Kicinski <kuba@kernel.org>
To: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: netdev@vger.kernel.org,
Zefir Kurtisi <zefir.kurtisi@westermo.com>,
Claudiu Manoil <claudiu.manoil@nxp.com>,
Wei Fang <wei.fang@nxp.com>, Clark Wang <xiaoning.wang@nxp.com>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
Ioana Ciornei <ioana.ciornei@nxp.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Jesper Dangaard Brouer <hawk@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Stanislav Fomichev <sdf@fomichev.me>,
Simon Horman <horms@kernel.org>,
bpf@vger.kernel.org, imx@lists.linux.dev,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net 2/3] net: enetc: pad short frames in software
Date: Thu, 2 Apr 2026 08:37:47 -0700 [thread overview]
Message-ID: <20260402083747.4f496c9a@kernel.org> (raw)
In-Reply-To: <20260401172246.1075883-3-vladimir.oltean@nxp.com>
On Wed, 1 Apr 2026 20:22:45 +0300 Vladimir Oltean wrote:
> The ENETC does not support BUF_LEN or FRM_LEN in TX buffer descriptors
> less than 16. This is written in the reference manual of all SoCs
> supported by the driver: LS1028A, i.MX943, i.MX95 etc.
>
> Frames must not have a FRM_LEN that is less than 16 bytes. Frames of
> 0-15 bytes are not supported.
> (...)
> The first descriptor in a chain must not have a BUFF_LEN that is less
> than 16 bytes.
>
> I don't think proper attention was paid to this during development, we
> found the text at the end of a bug investigation. Therefore, the driver
> does not enforce this.
AI points out that the frame may be longer than 16B but fragmented.
Only the Ethernet header is guaranteed to be in the linear part.
So you may need to also toss something like pskb_may_pull(16) after
that padding call.
--
pw-bot: cr
next prev parent reply other threads:[~2026-04-02 15:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-01 17:22 [PATCH net 0/3] Fix short frame transmission in enetc Vladimir Oltean
2026-04-01 17:22 ` [PATCH net 1/3] net: enetc: fix bogus TX ring consumer index after reinitialization Vladimir Oltean
2026-04-01 17:22 ` [PATCH net 2/3] net: enetc: pad short frames in software Vladimir Oltean
2026-04-02 15:37 ` Jakub Kicinski [this message]
2026-04-01 17:22 ` [PATCH net 3/3] net: enetc: pad short XDP frames coming from devmap Vladimir Oltean
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