From: Ferruh Yigit <ferruh.yigit@amd.com>
To: Joshua Washington <joshwash@google.com>,
Junfeng Guo <junfeng.guo@intel.com>,
Jeroen de Borst <jeroendb@google.com>,
Rushil Gupta <rushilg@google.com>
Cc: dev@dpdk.org
Subject: Re: [PATCH] net/gve: Update max_rx_pktlen to be based on MTU
Date: Thu, 26 Oct 2023 18:38:07 +0100 [thread overview]
Message-ID: <2d4b3aa4-bebc-4f04-87f8-b75f38e0558e@amd.com> (raw)
In-Reply-To: <20231016205948.2252342-1-joshwash@google.com>
On 10/16/2023 9:59 PM, Joshua Washington wrote:
> Before this patch, max_rx_pktlen was always set to UINT16_MAX. This, in
> conjunction with the MTU fix, causes problems with testpmd, as setting the
> packet length with the --max-pkt-len flag causes the MTU to be set
> higher than possible due to underflow.
>
> As an example, setting --max-pkt-len=1460 (the default MTU on Google
> Cloud VMs) causes testpmd to set the following:
> mtu = 1460 - eth_overhead,
>
> where eth_overhead = dev->max_rx_pktlen - dev->max_mtu = 65535 - 1460.
>
> Thus, mtu = 1460 - 65535 + 1460 = 2921 due to underflow.
>
> Signed-off-by: Joshua Washington <joshwash@google.com>
>
> Fixes: 030025b74202 ("net/gve: fix max MTU limit")
> Cc: joshwash@google.com
>
Cc: stable@dpdk.org
Applied to dpdk-next-net/main, thanks.
prev parent reply other threads:[~2023-10-26 17:38 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-16 20:59 Joshua Washington
2023-10-16 21:20 ` Stephen Hemminger
2023-10-16 22:58 ` Stephen Hemminger
2023-10-26 17:38 ` Ferruh Yigit [this message]
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