Re: [PATCH 3/3] drivers: always enable the null net driver [RFC]

Bruce Richardson
2026-01-22T14:59:34Z

On Thu, Jan 22, 2026 at 02:40:45PM +0100, Morten Brørup wrote:
> > From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> > Sent: Thursday, 22 January 2026 14.32
> >
> > On Thu, Jan 22, 2026 at 02:13:06PM +0100, Morten Brørup wrote:
> > > > From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> > > > Sent: Thursday, 22 January 2026 13.24
> > > >
> > > > Having the net_null driver always available can be convenient and
> > > > allows
> > > > use by unit tests, so add this trivial driver to the always-enable
> > > > list.
> > > >
> > > > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > > >
> > > > ---
> > > > I'm not sure if we want this to be always enabled or not, so
> > sending
> > > > this as an RFC. I can see definite advantages to doing so, but I
> > also
> > > > dislike having too many components on the always-enable list.
> > > >
> > > > Since I'm ambivilent myself, including this patch so the community
> > can
> > > > decide.
> > >
> > > I don't think real applications use this.
> > > If they do, they can include it manually.
> > >
> > > My main objection is:
> > > We are setting the wrong precedence if we make stuff like this
> > mandatory for convenience.
> > >
> > > But I agree with the reason you are suggesting it.
> > >
> > > Is there some other way it can be enabled for unit tests?
> > > Maybe the null driver can depend on the unit tests being built?
> > >
> > > I don't mind that the driver is being built.
> > > I just don't want it included by default when statically linking a
> > monolithic application.
> > >
> > > I'm flexible on this RFC, so it's a very soft NAK from me.
> > > If it can be disabled at build time, I'm OK with it. (But still
> > concerned about setting the wrong precedence.)
> > >
> > Yes, I agree.
> >
> > Why I'm proposing this is because, in order to give me faster rebuilds
> > and
> > because of the hardware I have available to me, I generally set up my
> > builds with "-Denable_drivers=net/intel/*", since that really speeds up
> > my
> > dev-build-test cycle. In doing so, though, I do miss out on having some
> > unit tests available when I run the fast-test suite, which is why I
> > suggested this addition in case there are others who limit the builds
> > to
> > just the hardware they are using.
>
> You can build with "-Denable_drivers=net/intel/*,net/null".
>
> Then I'll suggest an alternative to this patch:
> Change the fast-test application, so it emits an informational message about which tests are being skipped because the net/null driver is missing.
>
That is sadly non-trivial, and if we do so for net-null, we should also do
so for a bunch of other components where we disable tests if they are
missing. But the idea of just informing the user rather than force-enabling
the driver is a good one.