Regarding Mellanox bifurcated driver on Azure

Regarding Mellanox bifurcated driver on Azure

[Prashant Upadhyaya]

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Hi,

I am having a VM on Azure where I have got two 'accelerated networking'
interfaces of Mellanox
# lspci -nn|grep -i ether
6561:00:02.0 Ethernet controller [0200]: Mellanox Technologies MT27710
Family [ConnectX-4 Lx Virtual Function] [15b3:1016] (rev 80)
f08c:00:02.0 Ethernet controller [0200]: Mellanox Technologies MT27710
Family [ConnectX-4 Lx Virtual Function] [15b3:1016] (rev 80)

I have a DPDK application which needs to obtain 'all' packets from the NIC.
I installed the drivers, compiled DPDK24.11 (Ubuntu20.04), my app starts
and is able to detect the NIC's.
Everything looks good
myapp.out -c 0x07 -a f08c:00:02.0 -a 6561:00:02.0
EAL: Detected CPU lcores: 8
EAL: Detected NUMA nodes: 1
EAL: Detected shared linkage of DPDK
EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'PA'
EAL: VFIO support initialized
mlx5_net: Default miss action is not supported.
mlx5_net: Default miss action is not supported.
All Ports initialized
Port 0 is UP (50000 Mbps)
Port 1 is UP (50000 Mbps)

The trouble is that the ARP packets are not being picked up by my DPDK
application, I see them being delivered to the kernel via the eth interface
corresponding to the port (MLX is a bifurcated driver, you don't really
bind to the NIC, so you still see the eth interfaces at linux level and can
run tcpdump on those, I see ARP packets in the tcpdump there on the
interface)
I can receive UDP packets in my DPDK app though.

My application is not setting any rte_flow rules etc. so I was expecting
that by default my dpdk app would get all the packets as is normally the
case with other NIC's
Is there something I need to configure for Mellanox NIC somewhere such that
I get 'all' the packets including ARP packets in my DPDK app ?

Regards
-Prashant

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Re: Regarding Mellanox bifurcated driver on Azure

[Stephen Hemminger]

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Short answer Accelerated networking on Azure is not designed to support
bifurcated VF usage

On Fri, Apr 25, 2025, 10:47 Prashant Upadhyaya <praupadhyaya@gmail.com>
wrote:

> Hi,
>
> I am having a VM on Azure where I have got two 'accelerated networking'
> interfaces of Mellanox
> # lspci -nn|grep -i ether
> 6561:00:02.0 Ethernet controller [0200]: Mellanox Technologies MT27710
> Family [ConnectX-4 Lx Virtual Function] [15b3:1016] (rev 80)
> f08c:00:02.0 Ethernet controller [0200]: Mellanox Technologies MT27710
> Family [ConnectX-4 Lx Virtual Function] [15b3:1016] (rev 80)
>
> I have a DPDK application which needs to obtain 'all' packets from the NIC.
> I installed the drivers, compiled DPDK24.11 (Ubuntu20.04), my app starts
> and is able to detect the NIC's.
> Everything looks good
> myapp.out -c 0x07 -a f08c:00:02.0 -a 6561:00:02.0
> EAL: Detected CPU lcores: 8
> EAL: Detected NUMA nodes: 1
> EAL: Detected shared linkage of DPDK
> EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
> EAL: Selected IOVA mode 'PA'
> EAL: VFIO support initialized
> mlx5_net: Default miss action is not supported.
> mlx5_net: Default miss action is not supported.
> All Ports initialized
> Port 0 is UP (50000 Mbps)
> Port 1 is UP (50000 Mbps)
>
> The trouble is that the ARP packets are not being picked up by my DPDK
> application, I see them being delivered to the kernel via the eth interface
> corresponding to the port (MLX is a bifurcated driver, you don't really
> bind to the NIC, so you still see the eth interfaces at linux level and can
> run tcpdump on those, I see ARP packets in the tcpdump there on the
> interface)
> I can receive UDP packets in my DPDK app though.
>
> My application is not setting any rte_flow rules etc. so I was expecting
> that by default my dpdk app would get all the packets as is normally the
> case with other NIC's
> Is there something I need to configure for Mellanox NIC somewhere such
> that I get 'all' the packets including ARP packets in my DPDK app ?
>
> Regards
> -Prashant
>
>

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