The AWK code was added to deduplicate modules.order in case $(obj-m)
contains the same module multiple times, but it is actually unneeded
since commit
b2c885549122 ("kbuild: update modules.order only when
contained modules are updated").
The list is already deduplicated before being processed by AWK because
$^ is the deduplicated list of prerequisites.
(Please note the real-prereqs macro uses $^)
Yet, modules.order will contain duplication if two different Makefiles
build the same module:
foo/Makefile:
obj-m += bar/baz.o
foo/bar/Makefile:
obj-m += baz.o
However, the parallel builds cannot properly handle this case in the
first place. So, it is better to let it fail (as already done by
scripts/modules-check.sh).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
# Build modules
#
-# A module can be listed more than once in obj-m resulting in
-# duplicate lines in modules.order files. Those are removed
-# using awk while concatenating to the final file.
PHONY += modules
modules: $(if $(KBUILD_BUILTIN),vmlinux) modules_check modules_prepare
-cmd_modules_order = $(AWK) '!x[$$0]++' $(real-prereqs) > $@
+cmd_modules_order = cat $(real-prereqs) > $@
modules.order: $(subdir-modorder) FORCE
$(call if_changed,modules_order)
cmd_modules_order = { $(foreach m, $(real-prereqs), \
$(if $(filter %/modules.order, $m), cat $m, echo $(patsubst %.o,%.ko,$m));) :; } \
- | $(AWK) '!x[$$0]++' - > $@
+ > $@
$(obj)/modules.order: $(obj-m) FORCE
$(call if_changed,modules_order)