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authorMasahiro Yamada <yamada.masahiro@socionext.com>2018-11-30 04:05:26 +0300
committerMasahiro Yamada <yamada.masahiro@socionext.com>2018-12-01 17:13:14 +0300
commitbbda5ec671d3fe62faefa1cab7270aa586042a4b (patch)
treea1d375f74ad25efd2797bffaadfb0dc5fc1f65fe /scripts/Makefile.build
parentee3e46b7efd2954479f87030d31fda3c22bbc763 (diff)
downloadlinux-bbda5ec671d3fe62faefa1cab7270aa586042a4b.tar.xz
kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS
My main motivation of this commit is to clean up scripts/Kbuild.include and scripts/Makefile.build. Currently, CONFIG_TRIM_UNUSED_KSYMS works with a tricky gimmick; possibly exported symbols are detected by letting $(CPP) replace EXPORT_SYMBOL* with a special string '=== __KSYM_*===', which is post-processed by sed, and passed to fixdep. The extra preprocessing is costly, and hacking cmd_and_fixdep is ugly. I came up with a new way to find exported symbols; insert a dummy symbol __ksym_marker_* to each potentially exported symbol. Those dummy symbols are picked up by $(NM), post-processed by sed, then appended to .*.cmd files. I collected the post-process part to a new shell script scripts/gen_ksymdeps.sh for readability. The dummy symbols are put into the .discard.* section so that the linker script rips them off the final vmlinux or modules. A nice side-effect is building with CONFIG_TRIM_UNUSED_KSYMS will be much faster. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Nicolas Pitre <nico@linaro.org>
Diffstat (limited to 'scripts/Makefile.build')
-rw-r--r--scripts/Makefile.build7
1 files changed, 7 insertions, 0 deletions
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index cdb25d163b42..23ebf2508234 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -254,9 +254,15 @@ objtool_dep = $(objtool_obj) \
$(wildcard include/config/orc/unwinder.h \
include/config/stack/validation.h)
+ifdef CONFIG_TRIM_UNUSED_KSYMS
+cmd_gen_ksymdeps = \
+ $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd;
+endif
+
define rule_cc_o_c
$(call echo-cmd,checksrc) $(cmd_checksrc) \
$(call cmd_and_fixdep,cc_o_c) \
+ $(cmd_gen_ksymdeps) \
$(cmd_checkdoc) \
$(call echo-cmd,objtool) $(cmd_objtool) \
$(cmd_modversions_c) \
@@ -265,6 +271,7 @@ endef
define rule_as_o_S
$(call cmd_and_fixdep,as_o_S) \
+ $(cmd_gen_ksymdeps) \
$(call echo-cmd,objtool) $(cmd_objtool) \
$(cmd_modversions_S)
endef