• M
    kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS · bbda5ec6
    Masahiro Yamada 提交于
    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: NMasahiro Yamada <yamada.masahiro@socionext.com>
    Reviewed-by: NNicolas Pitre <nico@linaro.org>
    bbda5ec6
gen_ksymdeps.sh 399 字节
#!/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):"
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