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

[Jan Beulich <jbeulich@xxxxxxxx>]

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

Jan