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| author | Masahiro Yamada <yamada.masahiro@socionext.com> | 2018-11-30 10:05:26 +0900 |
|---|---|---|
| committer | Masahiro Yamada <yamada.masahiro@socionext.com> | 2018-12-01 23:13:14 +0900 |
| commit | bbda5ec671d3fe62faefa1cab7270aa586042a4b (patch) | |
| tree | a1d375f74ad25efd2797bffaadfb0dc5fc1f65fe /scripts/Kbuild.include | |
| parent | ee3e46b7efd2954479f87030d31fda3c22bbc763 (diff) | |
| download | linux-bbda5ec671d3fe62faefa1cab7270aa586042a4b.tar.bz2 | |
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/Kbuild.include')
| -rw-r--r-- | scripts/Kbuild.include | 28 |
1 files changed, 0 insertions, 28 deletions
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 6cf6a8b83b97..4b943f4d2226 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -260,39 +260,11 @@ if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ), \ @set -e; \ $(cmd_and_fixdep), @:) -ifndef CONFIG_TRIM_UNUSED_KSYMS - cmd_and_fixdep = \ $(echo-cmd) $(cmd_$(1)); \ scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;\ rm -f $(depfile); -else - -# Filter out exported kernel symbol names from the preprocessor output. -# See also __KSYM_DEPS__ in include/linux/export.h. -# We disable the depfile generation here, so as not to overwrite the existing -# depfile while fixdep is parsing it. -flags_nodeps = $(filter-out -Wp$(comma)-M%, $($(1))) -ksym_dep_filter = \ - case "$(1)" in \ - cc_*_c|cpp_i_c) \ - $(CPP) $(call flags_nodeps,c_flags) -D__KSYM_DEPS__ $< ;; \ - as_*_S|cpp_s_S) \ - $(CPP) $(call flags_nodeps,a_flags) -D__KSYM_DEPS__ $< ;; \ - boot*|build*|cpp_its_S|*cpp_lds_S|dtc|host*|vdso*) : ;; \ - *) echo "Don't know how to preprocess $(1)" >&2; false ;; \ - esac | tr ";" "\n" | sed -n 's/^.*=== __KSYM_\(.*\) ===.*$$/_\1/p' - -cmd_and_fixdep = \ - $(echo-cmd) $(cmd_$(1)); \ - $(ksym_dep_filter) | \ - scripts/basic/fixdep -e $(depfile) $@ '$(make-cmd)' \ - > $(dot-target).cmd; \ - rm -f $(depfile); - -endif - # Usage: $(call if_changed_rule,foo) # Will check if $(cmd_foo) or any of the prerequisites changed, # and if so will execute $(rule_foo). |