On 11/29/19 3:00 PM, Toke Høiland-Jørgensen wrote:
Daniel Borkmann <daniel@xxxxxxxxxxxxx> writes:
On 11/28/19 5:07 PM, Toke Høiland-Jørgensen wrote:
From: Jiri Olsa <jolsa@xxxxxxxxxx>
[...]
ifeq ($(srctree),)
srctree := $(patsubst %/,%,$(dir $(CURDIR)))
@@ -63,6 +72,19 @@ RM ?= rm -f
FEATURE_USER = .bpftool
FEATURE_TESTS = libbfd disassembler-four-args reallocarray zlib
FEATURE_DISPLAY = libbfd disassembler-four-args zlib
+ifdef LIBBPF_DYNAMIC
+ FEATURE_TESTS += libbpf
+ FEATURE_DISPLAY += libbpf
+
+ # for linking with debug library run:
+ # make LIBBPF_DYNAMIC=1 LIBBPF_DIR=/opt/libbpf
The Makefile already has BPF_DIR which points right now to
'$(srctree)/tools/lib/bpf/' and LIBBPF_PATH for the final one and
where $(LIBBPF_PATH)libbpf.a is expected to reside. Can't we improve
the Makefile to reuse and work with these instead of adding yet
another LIBBPF_DIR var which makes future changes in this area more
confusing? The libbpf build spills out libbpf.{a,so*} by default
anyway.
I see what you mean; however, LIBBPF_DIR is meant to be specifically an
override for the dynamic library, not just the path to libbpf.
Would it be less confusing to overload the LIBBPF_DYNAMIC variable
instead? I.e.,
make LIBBPF_DYNAMIC=1
would dynamically link against the libbpf installed in the system, but
make LIBBPF_DYNAMIC=/opt/libbpf
would override that and link against whatever is in /opt/libbpf instead?
WDYT?
Hm, given perf tool has similar LIB*_DIR vars in place for its libs, it probably
makes sense to stick with this convention as well then. Perhaps better in this
case to just rename s/BPF_DIR/BPF_SRC_DIR/, s/LIBBPF_OUTPUT/LIBBPF_BUILD_OUTPUT/,
and s/LIBBPF_PATH/LIBBPF_BUILD_PATH/ to make their purpose more clear.
One thing that would be good to do as well for this patch is to:
i) Document both LIBBPF_DYNAMIC and LIBBPF_DIR in the Makefile comment you
added at the top along with a simple usage example.
ii) Extend tools/testing/selftests/bpf/test_bpftool_build.sh with a dynamic
linking test case, e.g. building libbpf into a temp dir and pointing
LIBBPF_DIR to it for bpftool LIBBPF_DYNAMIC=1 build.
Thanks,
Daniel
