Re: Make 4.3 rebuilds .o files when unnecessary

[Tommaso Fonda]

Thank you for your reply. I will definitely try what you suggested in a few
days, and I'll report back my findings.
Regards,
--
Tommaso Fonda

Il giorno mer 18 nov 2020 alle ore 20:04 Paul Smith <psmith@gnu.org> ha
scritto:

> On Wed, 2020-11-18 at 16:38 +0100, Tommaso Fonda wrote:
> > When using make 4.3, as packaged in OpenSUSE Tumbleweed and Ubuntu
> > 20.10, running "make" always rebuilds the whole kernel tree, even
> > when no files have changed since the last time I completed a build.
> > As soon as I roll back to make 4.2, the behaviour goes back to
> > normal. Is this a bug?
>
> Well, since it's not the behavior you want there's clearly a bug
> SOMEWHERE.  If what you mean is it a bug in GNU make, there's no way we
> can know that based on the info provided.  It could also be a bug in
> your makefiles, that just happened to work OK for older versions of GNU
> make.
>
> Unfortunately I don't have the resources to check out your source tree
> and try to reproduce it, so someone else will have to do some
> investigation to narrow down the problem.
>
> The best way to do that is first, reduce the problem as much as
> possible; for example see if you can pass arguments to make so that it
> builds just one object file (the equivalent of "make foo.o" for
> example), where when you run that make command it doesn't rebuild with
> 4.2 but always rebuilds with 4.3.
>
> Then, run that command adding the --trace option to make and it should
> show you information on why it decided to rebuild.  You can compare
> that between the 4.2 and 4.3 releases, and if it's not clear what the
> problem is please feel free to ask here again.
>
>