path: root/samples/seccomp/.gitignore
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authorMasahiro Yamada <yamada.masahiro@socionext.com>2017-11-08 01:31:46 +0900
committerMasahiro Yamada <yamada.masahiro@socionext.com>2017-11-18 11:38:58 +0900
commitf7adc3124da019878186f1ebe98a13a1af041afd (patch)
tree5519de53ba24c13fd6591efb49b861756178238c /samples/seccomp/.gitignore
parent16f8259ca77d04f95e5ca90be1b1894ed45816c0 (diff)
kbuild: create built-in.o automatically if parent directory wants it
"obj-y += foo/" syntax requires Kbuild to visit the "foo" subdirectory and link built-in.o from that directory. This means foo/Makefile is responsible for creating built-in.o even if there is no object to link (in this case, built-in.o is an empty archive). We have had several fixups like commit 4b024242e8a4 ("kbuild: Fix linking error built-in.o no such file or directory"), then ended up with a complex condition as follows: ifneq ($(strip $(obj-y) $(obj-m) $(obj-) $(subdir-m) $(lib-target)),) builtin-target := $(obj)/built-in.o endif We still have more cases not covered by the above, so we need to add obj- := dummy.o in several places just for creating empty built-in.o. A key point is, the parent Makefile knows whether built-in.o is needed or not. If a subdirectory needs to create built-in.o, its parent can tell the fact when descending. If non-empty $(need-builtin) flag is passed from the parent, built-in.o should be created. $(obj-y) should be still checked to support the single target "%/". All of ugly tricks will go away. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
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