From 82caf3da8a7048a9268fc58ec5647ae969fab688 Mon Sep 17 00:00:00 2001 From: Viacheslav Ovsiienko Date: Mon, 28 Oct 2024 16:45:09 +0200 Subject: [PATCH] doc: clarify PCI Virtual Function MTU behavior in mlx5 The mlx5 NIC has a limitation regarding MTU configuration for PCI Virtual Functions (VFs), setting the MTU on a VF has no effect on the actual maximum packet size that can be received. Instead, the maximum receivable packet size for a VF is determined by the MTU configured on its associated Physical Function (PF). DPDK applications using VFs should be prepared to handle packets up to the size of the PF's configured MTU, regardless of any MTU settings applied to the VF itself. Signed-off-by: Viacheslav Ovsiienko --- doc/guides/nics/mlx5.rst | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst index 145c01fbda..2d753dd870 100644 --- a/doc/guides/nics/mlx5.rst +++ b/doc/guides/nics/mlx5.rst @@ -191,6 +191,14 @@ Limitations - IPv4/TCP with CVLAN filtering - L4 steering rules for port RSS of UDP, TCP and IP +- PCI Virtual Function MTU: + + MTU settings on PCI Virtual Functions have no effect. + The maximum receivable packet size for a VF is determined by the MTU + configured on its associated Physical Function. + DPDK applications using VFs must be prepared to handle packets + up to the maximum size of this PF port. + - For secondary process: - Forked secondary process not supported.