linux/scripts/gen_ksymdeps.sh
Masahiro Yamada bbda5ec671 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>
2018-12-01 23:13:14 +09:00

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#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
set -e
# List of exported symbols
ksyms=$($NM $1 | sed -n 's/.*__ksym_marker_\(.*\)/\1/p' | tr A-Z a-z)
if [ -z "$ksyms" ]; then
exit 0
fi
echo
echo "ksymdeps_$1 := \\"
for s in $ksyms
do
echo $s | sed -e 's:^_*: $(wildcard include/ksym/:' \
-e 's:__*:/:g' -e 's/$/.h) \\/'
done
echo
echo "$1: \$(ksymdeps_$1)"
echo
echo "\$(ksymdeps_$1):"