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authorMasahiro Yamada <masahiroy@kernel.org>2020-05-25 00:42:15 +0900
committerMasahiro Yamada <masahiroy@kernel.org>2020-05-29 03:08:49 +0900
commite9e81b634303b215e83beced03f04f02f7893442 (patch)
treec1ba8052b8020f6e3affb3e8b6e085933db7e4f1 /Makefile
parent454753d9f67ae40b6a2142ddb6b4dbdcc9654aa9 (diff)
downloadlinux-e9e81b634303b215e83beced03f04f02f7893442.tar.bz2
kbuild: disallow multi-word in M= or KBUILD_EXTMOD
$(firstword ...) in scripts/Makefile.modpost was added by commit 3f3fd3c05585 ("[PATCH] kbuild: allow multi-word $M in Makefile.modpost") to build multiple external module directories. It was a solution to resolve symbol dependencies when an external module depends on another external module. Commit 0d96fb20b7ed ("kbuild: Add new Kbuild variable KBUILD_EXTRA_SYMBOLS") introduced another solution by passing symbol info via KBUILD_EXTRA_SYMBOLS, then broke the multi-word M= support. include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \ $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile) ... does not work if KBUILD_EXTMOD contains multiple words. This feature has been broken for more than a decade. Remove the bitrotten code, and stop parsing if M or KBUILD_EXTMOD contains multiple words. As Documentation/kbuild/modules.rst explains, if your module depends on another one, there are two solutions: - add a common top-level Kbuild file - use KBUILD_EXTRA_SYMBOLS Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'Makefile')
-rw-r--r--Makefile3
1 files changed, 3 insertions, 0 deletions
diff --git a/Makefile b/Makefile
index 72eb55a36545..48a2dfaf3bf3 100644
--- a/Makefile
+++ b/Makefile
@@ -218,6 +218,9 @@ ifeq ("$(origin M)", "command line")
KBUILD_EXTMOD := $(M)
endif
+$(if $(word 2, $(KBUILD_EXTMOD)), \
+ $(error building multiple external modules is not supported))
+
export KBUILD_CHECKSRC KBUILD_EXTMOD
extmod-prefix = $(if $(KBUILD_EXTMOD),$(KBUILD_EXTMOD)/)