From: Stephen Hemminger <stephen@networkplumber.org>
To: Xavier Guillaume <xavier.guillaume@ovhcloud.com>
Cc: <dev@dpdk.org>, <linville@tuxdriver.com>
Subject: Re: [PATCH v1 3/3] net/af_packet: support jumbo frames
Date: Mon, 9 Mar 2026 09:03:47 -0700 [thread overview]
Message-ID: <20260309090347.2fc2c74c@phoenix.local> (raw)
In-Reply-To: <20260306092013.2205076-4-xavier.guillaume@ovhcloud.com>
On Fri, 6 Mar 2026 10:20:13 +0100
Xavier Guillaume <xavier.guillaume@ovhcloud.com> wrote:
> Derive max_rx_pktlen and max_mtu from the actual TPACKET ring
> frame size rather than the static RTE_ETHER_MAX_LEN (1518).
> This allows jumbo frame support when the user specifies a
> larger framesz devarg at vdev creation time, for example:
>
> --vdev=net_af_packet0,iface=eth0,framesz=9216
>
> The advertised capabilities now accurately reflect what the
> configured ring can handle, avoiding both false limitations
> with large frames and false promises with small ones.
>
> Signed-off-by: Xavier Guillaume <xavier.guillaume@ovhcloud.com>
> ---
AI had this observation.
Patch 3: max_mtu subtracts RTE_ETHER_CRC_LEN, but the kernel
strips CRC before placing data in the TPACKET ring, so MTU is
understated by 4 bytes. This is conservative and safe, and
matches what af_xdp does, so probably fine as-is.
next prev parent reply other threads:[~2026-03-09 16:03 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-06 9:20 [PATCH v1 0/3] net/af_packet: fix MTU handling and add jumbo frame support Xavier Guillaume
2026-03-06 9:20 ` [PATCH v1 1/3] net/af_packet: fix MTU set data size calculation Xavier Guillaume
2026-03-06 9:20 ` [PATCH v1 2/3] net/af_packet: fix receive buffer overflow Xavier Guillaume
2026-03-06 9:20 ` [PATCH v1 3/3] net/af_packet: support jumbo frames Xavier Guillaume
2026-03-09 16:03 ` Stephen Hemminger [this message]
2026-03-09 16:10 ` [PATCH v2 0/3] net/af_packet: fix MTU handling and add jumbo frame support Xavier Guillaume
2026-03-09 16:10 ` [PATCH v2 1/3] net/af_packet: fix MTU set data size calculation Xavier Guillaume
2026-03-09 16:10 ` [PATCH v2 2/3] net/af_packet: fix receive buffer overflow Xavier Guillaume
2026-03-09 16:10 ` [PATCH v2 3/3] net/af_packet: support jumbo frames Xavier Guillaume
2026-03-10 23:31 ` Stephen Hemminger
2026-03-12 13:32 ` Xavier Guillaume
2026-03-12 16:20 ` Stephen Hemminger
2026-03-09 20:16 ` [PATCH v2 0/3] net/af_packet: fix MTU handling and add jumbo frame support Stephen Hemminger
2026-03-09 20:49 ` [PATCH] net/af_packet: add multi-segment mbuf support for jumbo frames Sriram Yagnaraman
2026-03-09 21:02 ` [PATCH v2] " Sriram Yagnaraman
2026-03-10 14:02 ` Stephen Hemminger
2026-03-10 20:02 ` Sriram Yagnaraman
2026-03-16 16:02 ` Stephen Hemminger
2026-03-19 9:25 ` Sriram Yagnaraman
2026-03-10 1:55 ` [PATCH v2 0/3] net/af_packet: fix MTU handling and add jumbo frame support Stephen Hemminger
2026-03-10 11:21 ` [PATCH v3 " Xavier Guillaume
2026-03-10 11:21 ` [PATCH v3 1/3] net/af_packet: fix MTU set data size calculation Xavier Guillaume
2026-03-10 11:21 ` [PATCH v3 2/3] net/af_packet: fix receive buffer overflow Xavier Guillaume
2026-03-10 11:21 ` [PATCH v3 3/3] net/af_packet: support jumbo frames Xavier Guillaume
2026-03-11 16:03 ` [PATCH v3 0/3] net/af_packet: fix MTU handling and add jumbo frame support Stephen Hemminger
2026-03-12 18:46 ` Stephen Hemminger
2026-03-16 15:59 ` Stephen Hemminger
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