Re: [PATCH] build: make sure build fails when running kconfig fails

[Anthony PERARD <anthony.perard@xxxxxxxxx>]

On Tue, Feb 20, 2024 at 01:20:16PM +0100, Jan Beulich wrote:
> On 20.02.2024 12:18, Anthony PERARD wrote:
> > On Tue, Feb 20, 2024 at 09:43:56AM +0100, Jan Beulich wrote:
> >> Because of using "-include", failure to (re)build auto.conf (with
> >> auto.conf.cmd produced as a secondary target) won't stop make from
> >> continuing the build. Arrange for it being possible to drop the - from
> >> Rules.mk, requiring that the include be skipped for tools-only targets.
> >> Note that relying on the inclusion in those cases wouldn't be correct
> >> anyway, as it might be a stale file (yet to be rebuilt) which would be
> >> included, while during initial build, the file would be absent
> >> altogether.
> >>
> >> Fixes: 8d4c17a90b0a ("xen/build: silence make warnings about missing 
> >> auto.conf*")
> >> Reported-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> >> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> > 
> > Just to make sure, this patch is a workaround to a harmless bug in older
> > version of GNU Make which print spurious error messages, and said bug as
> > been fixed in GNU Make 4.2, right? Bug report:
> > 
> >     bug #102: Make prints an incorrect error for missing includes
> >     https://savannah.gnu.org/bugs/?func=detailitem&item_id=102
> 
> Assuming you mean the change referenced in Fixes: - yes, that's my
> understanding. (Whether the referenced make bug is the one I can't tell,
> though. But it looks like it is.)
> 
> >> --- a/xen/Makefile
> >> +++ b/xen/Makefile
> >> @@ -375,6 +375,7 @@ $(KCONFIG_CONFIG): tools_fixdep
> >>  # This exploits the 'multi-target pattern rule' trick.
> >>  # The syncconfig should be executed only once to make all the targets.
> >>  include/config/%.conf include/config/%.conf.cmd: $(KCONFIG_CONFIG)
> >> +  $(Q)rm -f include/config/$*.conf
> > 
> > Maybe this should say "include/config/auto.conf" instead of using "$*".
> > "syncconfig" is going to generate "auto.conf" and not "$*.conf". And it
> > would make easier to find the "rm" command via "grep".
> 
> Generally I advocate for using $* wherever possible in pattern rules. If,

Well, it might look like a pattern rule, but it isn't one. It's a
"groupes targets" rule that works on version of Make that doesn't have
this brand new feature. It would be written as:
    include/config/auto.conf include/config/auto.conf.cmd&: $(KCONFIG_CONFIG)

Second, the other command in the recipe doesn't use "$*", so it's not
possible to use this rule with a value of $* other than "auto".

> however, replacing that is the only way to get an ack for this change, then
> I would (hesitantly) do so.

Yes please, even if I don't like the patch. I hope it isn't going to
byte us later if something in "tools/" happens to start depending on
Kconfig (only fixdep and kconfig need to not depend on kconfig at the
moment). But the patch currently works and looks ok. So, with "$*"
replace by "auto", you can add my "Reviewed-by: Anthony PERARD
<anthony.perard@xxxxxxxxxx>".

Thanks,

-- 
Anthony PERARD