On Mon, 16 Oct 2023 13:59:48 -0700 Joshua Washington <joshw...@google.com> 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 <joshw...@google.com> This seems wrong and is not what other drivers do. Other drivers give the absolute maximum in the dev_info so that application can size accordingly.
