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

[Long Li]

> Subject: [EXTERNAL] Re: [RFC] net/vdev_netvsc: check for NetVSC device before
> auto-probe
> 
> 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.

Can we set up a default config of not auto probing net_vdev_netvsc? Or some kind of flags that says a driver should not be auto loaded.

Most customers are running "vdev" arguments to load them in their DPDK application.