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

[Thomas Monjalon]

26/03/2020 21:09, Mark Bloch:
> 
> On 3/26/2020 12:00, Benoit Ganne (bganne) wrote:
> >> 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_20.02/0002-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?
> 
> Should be fixed by those 3 commits (last 1 one is just cosmetic):
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=dc392fc56f39a00a46d6db2d150571ccafe99734
> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=c268ca6087f553bfc0e16ffec412b983ffe32fd4
> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=2f5438ca0ee01a1b3a9c37e3f33d47c8122afe74

Thanks for the patches Mark.

> > 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

1 looks to be addressed with patches above.

> >  2) mlx5 PMD enforce that both link speed is defined and link is up to update interface state

Yes we can look at this issue.

> > 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,

I agree that link speed is less important than link status.

> > esp in a virtual environment it usually does not mean much,

Yes the link speed is shared between all VFs.

> > but we do care about link state.