how to get a well debuggable busybox binary ?
whenever i try to debug busybox, gdb (7.6.2) is completely clueless,
especially upon entering applet_main. for example in ping.c, after
breaking on ping_main, gdb lists the BSD copyright header at the end of
the file as the actual sourceline. stepping with "n" just makes the
program run through.
so in the end i end up extracting all the needed code and stuff it into
a standalone C file so i can manage to build it with my own debug
CFLAGS, without -fomit-framepointer, FAST_FUNC, MAIN_EXTERNALLY_VISIBLE,
and all the weird microoptimization c/ldflags/macros that are hardcoded
everywhere, as well as the multiple levels of main() indirection. the
trylink script is also completely useless for debugging as it uses
dozens of exotic and untested ld flags to shave off a byte or 2.
i use the following to build busybox in "debug mode"
if [ ! -z "$DEBUGBUILD" ] ; then
debugcflags="-O0 -g"
sed -i 's/# CONFIG_DEBUG is not set/CONFIG_DEBUG=y/' .config
sed -i 's/# CONFIG_DEBUG_PESSIMIZE is not
set/CONFIG_DEBUG_PESSIMIZE=y/' .config
sed -i 's/CONFIG_NO_DEBUG_LIB=y/# CONFIG_NO_DEBUG_LIB is not
set/' .config
fi
make V=1 LDFLAGS=-static HOSTLDFLAGS=-static \
CFLAGS_busybox="$debugcflags -Wl,-z,muldefs
-Werror-implicit-function-declaration" \
HOSTCC="$CC -static" CC="$CC -static" HOSTCFLAGS=-D_GNU_SOURCE
and then use busybox_unstripped.
i'm pretty sure there must be a better way as i cant imagine anyone
debugging busybox copy/pasting for hours. any tips are welcome.
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