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authorMasahiro Yamada <masahiroy@kernel.org>2022-05-27 19:01:53 +0900
committerMasahiro Yamada <masahiroy@kernel.org>2022-06-01 23:07:29 +0900
commitc6031b1dbbbfec03891bf1baefa2e0803d705601 (patch)
tree173a64a7a43628e63041a824f6879811838b3460 /scripts/Makefile.build
parentcd968b97c49214e6557381bddddacbd0e0fb696e (diff)
kbuild: make *.mod rule robust against too long argument error
Like built-in.a, the command length of the *.mod rule scales with the depth of the directory times the number of objects in the Makefile. Add $(obj)/ by the shell command (awk) instead of by Make's builtin function. In-tree modules still have some room to the limit (ARG_MAX=2097152), but this is more future-proof for big modules in a deep directory. For example, you can build i915 as a module (CONFIG_DRM_I915=m) and compare drivers/gpu/drm/i915/.i915.mod.cmd with/without this commit. The issue is more critical for external modules because the M= path can be very long as Jeff Johnson reported before [1]. [1] https://lore.kernel.org/linux-kbuild/4c02050c4e95e4cb8cc04282695f8404@codeaurora.org/ Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
Diffstat (limited to 'scripts/Makefile.build')
-rw-r--r--scripts/Makefile.build6
1 files changed, 4 insertions, 2 deletions
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 3c1e20e4a4fc..a1edbfe4310b 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -275,8 +275,10 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
$(call if_changed_rule,cc_o_c)
$(call cmd,force_checksrc)
-cmd_mod = echo $(addprefix $(obj)/, $(call real-search, $*.o, .o, -objs -y -m)) | \
- $(AWK) -v RS='( |\n)' '!x[$$0]++' > $@
+# To make this rule robust against "Argument list too long" error,
+# ensure to add $(obj)/ prefix by a shell command.
+cmd_mod = echo $(call real-search, $*.o, .o, -objs -y -m) | \
+ $(AWK) -v RS='( |\n)' '!x[$$0]++ { print("$(obj)/"$$0) }' > $@
$(obj)/%.mod: FORCE
$(call if_changed,mod)