Hangbin Liu <haliu@xxxxxxxxxx> writes:
> On Wed, Oct 28, 2020 at 09:00:41PM -0600, David Ahern wrote:
>> >> nope. you need to be able to handle this. Ubuntu 20.10 was just
>> >> released, and it has a version of libbpf. If you are going to integrate
>> >> libbpf into other packages like iproute2, it needs to just work with
>> >> that version.
>> >
>> > OK, I can replace bpf_program__section_name by bpf_program__title().
>>
>> I believe this one can be handled through a compatability check. Looks
>> the rename / deprecation is fairly recent (78cdb58bdf15f from Sept 2020).
>
> Hi David,
>
> I just come up with another way. In configure, build a temp program and update
> the function checking every time is not graceful. How about just check the
> libbpf version, since libbpf has exported all functions in src/libbpf.map.
>
> Currently, only bpf_program__section_name() is added in 0.2.0, all other
> needed functions are supported in 0.1.0.
>
> So in configure, the new check would like:
Why is this easier than just checking for the function you need? In
xdp-tools configure we have a test like this:
check_perf_consume()
{
cat >$TMPDIR/libbpftest.c <<EOF
#include <bpf/libbpf.h>
int main(int argc, char **argv) {
perf_buffer__consume(NULL);
return 0;
}
EOF
libbpf_err=$($CC -o $TMPDIR/libbpftest $TMPDIR/libbpftest.c $LIBBPF_CFLAGS $LIBBPF_LDLIBS 2>&1)
if [ "$?" -eq "0" ]; then
echo "HAVE_LIBBPF_PERF_BUFFER__CONSUME:=y" >>"$CONFIG"
echo "yes"
else
echo "HAVE_LIBBPF_PERF_BUFFER__CONSUME:=n" >>"$CONFIG"
echo "no"
fi
}
Just do that for __section_name(), and you'll also be able to work with
custom libbpf versions using LIBBPF_DIR.
> static const char *get_bpf_program__section_name(const struct bpf_program *prog)
> {
> #ifdef HAVE_LIBBPF_SECTION_NAME
> return bpf_program__section_name(prog);
> #else
> return bpf_program__title(prog, false);
> #endif
> }
This bit is fine :)
-Toke
