Re: [PATCH] of: unittest: Statically apply overlays using fdtoverlay

[Bill Mills]

On 1/12/21 3:37 AM, Viresh Kumar wrote:
> On 11-01-21, 20:22, Bill Mills wrote:
> > On 1/11/21 5:06 PM, Frank Rowand wrote:
> > > NACK to this specific patch, in its current form.
> > >
> > > There are restrictions on applying an overlay at runtime that do not apply
> > > to applying an overlay to an FDT that will be loaded by the kernel during
> > > early boot.  Thus the unittest overlays _must_ be applied using the kernel
> > > overlay loading methods to test the kernel runtime overlay loading feature.
> > >
> > > I agree that testing fdtoverlay is a good idea.  I have not looked at the
> > > parent project to see how much testing of fdtoverlay occurs there, but I
> > > would prefer that fdtoverlay tests reside in the parent project if practical
> > > and reasonable.  If there is some reason that some fdtoverlay tests are
> > > more practical in the Linux kernel repository then I am open to adding
> > > them to the Linux kernel tree.
>
> I wasn't looking to add any testing for fdtoverlay in the kernel, but
> then I stumbled upon unit-tests here and thought it would be a good
> idea to get this built using static tools as well, as we aren't
> required to add any new source files for this and the existing tests
> already cover a lot of nodes.
>
> And so I am fine if we don't want to do this stuff in kernel.
>
> > I thought we were aligned that any new overlays into the kernel today would
> > only be for boot loader applied case.  Applying overlays at kernel runtime
> > was out of scope at your request.
> >
> > Rob had requested that the overlays be test applied at build time.  I don't
> > think there is any way to test the kernel runtime method at build time
> > correct?
> >
> > Please clarify your concern and your suggested way forward.
>
> The kernel does some overlay testing currently (at kernel boot only,
> not later), to see if the overlays get applied correctly or not, these
> are the unit tests.
>
> What Frank is probably saying is that the unit-tests dtbs shouldn't
> get used for testing fdtoverlay stuff. He isn't asking to support
> runtime application of overlays, but to not do fdtoverlay testing in
> the kernel.

Thanks Viresh, that makes sense.  Sorry for the confusion Frank.

--
Bill Mills