Re: [PATCH] build/xen: fail to rebuild if Kconfig fails

[Jan Beulich <jbeulich@xxxxxxxx>]

On 15.02.2024 12:04, Roger Pau Monné wrote:
> On Thu, Feb 15, 2024 at 11:43:02AM +0100, Jan Beulich wrote:
>> On 15.02.2024 11:28, Roger Pau Monné wrote:
>>> Without the reordering the include of include/config/auto.conf will
>>> always succeed on rebuilds, because the include is done before
>>> executing the include/config/%.conf.cmd target that does the `rm`.
>>
>> That's a dual target: It also handles include/config/%.conf. I.e.
>> because of this ...
>>
>>> With the current order the include of include/config/%.conf.cmd that
>>> triggers the re-build of auto.conf happens after having included the
>>> file already.
>>
>> ... either include would trigger this same rule. IOW I'm afraid I'm still
>> not seeing what is gained by the re-ordering. I'm also unconvinced that
>> "triggers" in the sense you use it is actually applicable. Quoting make
>> doc again: "Once it has finished reading makefiles, make will try to
>> remake any that are out of date or don’t exist." To me this means that
>> first all makefile reading will finish, and then whichever included files
>> need re-making will be re-made.
> 
> Without the re-ordering the execution is not stopped on failure to
> generate include/config/auto.conf:
> 
> # gmake -j8 xen clang=y
> gmake -C xen install
> gmake[1]: Entering directory '/root/src/xen/xen'
> rm -rf include/config/auto.conf
> tools/kconfig/conf  --syncconfig Kconfig
> common/Kconfig:2: syntax error
> common/Kconfig:1: invalid statement
> gmake[2]: *** [tools/kconfig/Makefile:73: syncconfig] Error 1
> gmake[1]: Failed to remake makefile 'include/config/auto.conf'.
>   UPD     include/xen/compile.h
>  Xen 4.19-unstable
> gmake[3]: Nothing to be done for 'all'.
> [...]
> 
> With the re-ordering:
> 
> # gmake -j8 xen clang=y
> gmake -C xen install
> gmake[1]: Entering directory '/root/src/xen/xen'
> rm -rf include/config/auto.conf
> tools/kconfig/conf  --syncconfig Kconfig
> common/Kconfig:2: syntax error
> common/Kconfig:1: invalid statement
> gmake[2]: *** [tools/kconfig/Makefile:73: syncconfig] Error 1
> gmake[1]: *** [Makefile:379: include/config/auto.conf] Error 2
> gmake[1]: Leaving directory '/root/src/xen/xen'
> gmake: *** [Makefile:143: install-xen] Error 2
> #
> 
> So the re-ordering is meaningful.

Hmm, I was about to say "no, it isn't" but then remembered to try newer
make. With 3.81 all is working as intended with no re-ordering. I wonder
if this isn't something with make, rather than our makefiles ...

Jan