[dpdk-users] CX4-Lx VF link status in Azure

[Benoit Ganne (bganne)]

> Pasting back this important info:
> "
> Note that ethtool and '/sys/class/net/<iface>/speed' also fails
> to report the link speed (but not the link status).
> "
> 
> 26/03/2020 19:27, Benoit Ganne (bganne):
> > Yes everything is initialized correctly. The netdev itself is configured
> and usable from Linux (ping etc.). Just removing the over-strict check in
> mlx5 PMD is enough for everything to work fine:
> https://gerrit.fd.io/r/c/vpp/+/26152/1/build/external/patches/dpdk_20.02/0
> 002-mlx5-azure-workaround.patch
> > The link speed is unknown but this is not issue, and link state and
> other link info are correctly reported.
> > Thomas, any input regarding this behavior in mlx5 PMD?
> 
> I am not aware about the lack of link speed info.
> It is probably not specific to ConnectX-4 Lx.
> I guess it happens only with Hyper-V?

For me there are 2 separate issues:
 1) Linux kernel driver does not report link speed in Azure for CX4-Lx in Ubuntu 18.04
 2) mlx5 PMD enforce that both link speed is defined and link is up to update interface state

If (1) is fixed, (2) should work, but to me (2) is too strict for no good reason: we do not really care about reported link speed, esp in a virtual environment it usually does not mean much, but we do care about link state.

ben