On Thu, May 12, 2022 at 05:08:29PM -0700, Andrii Nakryiko wrote:
> On Thu, May 12, 2022 at 4:44 PM Daniel Müller <deso@xxxxxxxxxx> wrote:
> >
> > Two of the BPF selftests hardcode the path to /sys/kernel/btf/vmlinux.
> > The kernel image could potentially exist at a different location.
> > libbpf_find_kernel_btf(), as introduced by commit fb2426ad00b1 ("libbpf:
> > Expose bpf_find_kernel_btf as a LIBBPF_API"), knows about said
> > locations.
> >
> > This change switches these two tests over to using this function
> > instead, making the tests more likely to be runnable when
> > /sys/kernel/btf/vmlinux may not be present and setting better precedent.
> >
> > Signed-off-by: Daniel Müller <deso@xxxxxxxxxx>
> > ---
> > tools/testing/selftests/bpf/prog_tests/libbpf_probes.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c b/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c
> > index 9f766dd..61c81a9 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c
> > @@ -11,8 +11,8 @@ void test_libbpf_probe_prog_types(void)
> > const struct btf_enum *e;
> > int i, n, id;
> >
> > - btf = btf__parse("/sys/kernel/btf/vmlinux", NULL);
>
> Selftests go hand in hand with kernel and generally assume specific
> kernel features enabled (like BTF and sysfs) and having very recent
> (if not latest) kernel. So there is nothing bad about loading
> /sys/kernel/btf/vmlinux, I think, it's actually more straightforward
> to follow the code when it is used explicitly. Libbpf's logic for
> finding kernel BTF in other places is for older systems. So I'd leave
> it as is.
Sounds good to me. Feel free to ignore the patch then.
Daniel
