Re: [PATCH] perf data: Fix babeltrace detection

[Andi Kleen]

On Tue, Oct 08, 2019 at 01:52:40PM +0200, Jiri Olsa wrote:
> On Mon, Oct 07, 2019 at 10:41:20AM -0700, Andi Kleen wrote:
> > From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> > 
> > The symbol the feature file checks for is now actually in -lbabeltrace,
> > not -lbabeltrace-ctf, at least as of libbabeltrace-1.5.6-2.fc30.x86_64
> > 
> > Always add both libraries to fix the feature detection.
> 
> well, we link with libbabeltrace-ctf.so which links with libbabeltrace.so
> 
> I guess we can link it as well, but where do you see it fail?

On FC30 the .so file is just a symlink, so it doesn't pull
in the other library.

$ gcc test-libbabeltrace.c -lbabeltrace-ctf
/usr/bin/ld:
/usr/lib/gcc/x86_64-redhat-linux/9/../../../../lib64/libbabeltrace-ctf.so:
undefined reference to `bt_packet_seek_get_error'
/usr/bin/ld:
/usr/lib/gcc/x86_64-redhat-linux/9/../../../../lib64/libbabeltrace-ctf.so:
undefined reference to `bt_packet_seek_set_error'
collect2: error: ld returned 1 exit status

$ ls -l /usr/lib64/libbabeltrace-ctf.so
lrwxrwxrwx 1 root root 26 Jan 31  2019 /usr/lib64/libbabeltrace-ctf.so
-> libbabeltrace-ctf.so.1.0.0

$ rpm -qf /usr/lib64/libbabeltrace-ctf.so
libbabeltrace-devel-1.5.6-2.fc30.x86_64

-Andi