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From:   Vegard Nossum <vegard.nossum@oracle.com>
To:     Masahiro Yamada <yamada.masahiro@socionext.com>
Cc:     Jens Axboe <axboe@kernel.dk>, LKML <linux-kernel@vger.kernel.org>,
        linux-kbuild@vger.kernel.org
Subject: single target builds are broken
Message-ID: <a5ce79eb-be9d-df97-0b58-5aee5a48f4d3@oracle.com>
Date:   Tue, 31 Mar 2020 11:16:30 +0200
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Hi,

I often run 'make foo/bar.o' as part of my workflow, even when bar.o is
not specified in any kernel makefile, and this has worked just fine for
years.

This is broken after commit 394053f4a4b3e3eeeaa67b67fc886a9a75bd9e4d
(kbuild: make single targets work more correctly) and just gives an error:

$ make kernel/test.o
   CALL    scripts/checksyscalls.sh
   CALL    scripts/atomic/check-atomics.sh
   DESCEND  objtool
make[2]: *** No rule to make target 'kernel/test.o'.  Stop.
scripts/Makefile.build:502: recipe for target '__build' failed
make[1]: *** [__build] Error 2
Makefile:1670: recipe for target 'kernel' failed
make: *** [kernel] Error 2

For top-level objects (e.g. 'make bar.o') the situation is even worse,
since make exits with status 0 without building anything :-/

Is there any chance we can get this back? It was super useful for me.


Vegard