Re: [dpdk-dev] [PATCH] net/vdev_netvsc: print warning if Mellanox devices are not configured

[Thomas Monjalon <thomas@monjalon.net>]

24/05/2019 19:11, Stephen Hemminger:
> On Fri, 24 May 2019 19:05:20 +0200
> Thomas Monjalon <thomas@monjalon.net> wrote:
> 
> > > > > device drivers on Hyper-V/Azure.  If the build system supported dependencies
> > > > > (like Linux kbuild) this would not be necessary. Meson only does dynamic dependencies
> > > > > so that doesn't help.
> > > > > 
> > > > > This is a warning and not fatal only because application will still at
> > > > > least run, and somebody may want to run with SR-IOV with Intel NIC's on Hyper-V.
> > > > > 
> > > > > 
> > > > > The warning is just to give users better immediate feedback rather than
> > > > > trying to diagnose poor performance or mystery device not found messages.    
> > > > 
> > > > 
> > > > It really looks strange to me.
> > > > What you need is to fail at compilation if requested PMD is not built.
> > > > I would advise to work on a script to configure meson.  
> > > 
> > > None of the people that ran into this were using meson build.
> > > For example, VPP doesn't use meson.  
> > 
> > They will use meson when makefile will be removed :)
> > 
> > Anyway, no matter the build system, what we want is a way
> > to guide users to a proper DPDK installation.
> > Your solution is to add some very specific logs.
> > My proposal is to guide the user with a script and some
> > specific parameters so it will fail if a required dependency is not met.
> 
> Not familiar enough with meson magic syntax to make vdev_netvsc not build
> without MLX. But that would just be pushing the mystery failure further
> down the road.

I think you did not understand my proposal.
Let's take an example. You give this instruction to build DPDK:
	buildtools/build-require.sh vdev_netvsc mlx4
If mlx4 is not built then it will fail with this message:
	librte_pmd_mlx4 failed to build
So the user knows what went wrong. No mystery.


> Another alternative would be to drop vdev_netvsc from the default Linux
> build. That way users would have to enable it manually.
> 
> My preferred solution would be to just kill vdev_netvsc and go to only netvsc PMD
> but that is a couple releases away.