[RFC] net/vdev_netvsc: check for NetVSC device before auto-probe

[Stephen Hemminger]

On Sun, 22 Feb 2026 12:48:13 -0800
Stephen Hemminger <stephen at networkplumber.org> wrote:

> The custom scan callback unconditionally injects net_vdev_netvsc into
> the devargs list on any Hyper-V system without checking whether NetVSC
> interfaces actually exist. This causes the eal_flags_vdev_opt_autotest
> to fail on GitHub Actions runners (which are Azure/Hyper-V VMs) because
> the vdev bus probes both the test's intended vdev and the injected
> net_vdev_netvsc, which fails to initialize on systems without NetVSC
> interfaces.
> 
> Check whether at least one NetVSC interface exists (via the sysfs
> class_id check the driver already uses) before adding devargs in the
> scan callback.
> 
> Fixes: 56252de779a6 ("net/vdev_netvsc: add automatic probing")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
> ---

This is not sufficient to fix the github problem.
The container still has an interface, and cloud-init has given it
an address. But it has no route to outside (in container).

It looks like the whole automagic vdev_netvsc model is so brittle
it should be removed.