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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/Kbuild.include
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/Kbuild.include')
-rw-r--r--scripts/Kbuild.include28
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).