On 2023/10/17 23:15, Daniel Borkmann wrote:
On 10/16/23 3:03 PM, Akihiko Odaki wrote:
When linking statically, libraries may require other dependencies to be
included to ld flags. In particular, libelf may require libzstd. Use
pkg-config to determine such dependencies.
Signed-off-by: Akihiko Odaki <akihiko.odaki@xxxxxxxxxx>
---
V3 -> V4: Added "2> /dev/null".
V2 -> V3: Added missing "echo".
V1 -> V2: Implemented fallback, referring to HOSTPKG_CONFIG.
tools/testing/selftests/bpf/Makefile | 4 +++-
tools/testing/selftests/bpf/README.rst | 2 +-
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/bpf/Makefile
b/tools/testing/selftests/bpf/Makefile
index caede9b574cb..009e907a8abe 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -4,6 +4,7 @@ include ../../../scripts/Makefile.arch
include ../../../scripts/Makefile.include
CXX ?= $(CROSS_COMPILE)g++
+PKG_CONFIG ?= $(CROSS_COMPILE)pkg-config
CURDIR := $(abspath .)
TOOLSDIR := $(abspath ../../..)
@@ -31,7 +32,8 @@ CFLAGS += -g -O0 -rdynamic -Wall -Werror $(GENFLAGS)
$(SAN_CFLAGS) \
-I$(CURDIR) -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR) \
-I$(TOOLSINCDIR) -I$(APIDIR) -I$(OUTPUT)
LDFLAGS += $(SAN_LDFLAGS)
-LDLIBS += -lelf -lz -lrt -lpthread
+LDLIBS += $(shell $(PKG_CONFIG) --libs libelf zlib 2> /dev/null ||
echo -lelf -lz) \
+ -lrt -lpthread
ifneq ($(LLVM),)
# Silence some warnings when compiled with clang
Staring at tools/bpf/resolve_btfids/Makefile, I'm trying to understand
why we
cannot replicate something similar for BPF selftests?
For example, with your patch, why is it necessary to now have PKG_CONFIG
and
another HOSTPKG_CONFIG var?
It's because at least Debian does have wrappers of pkg-config for cross
compile targets. You can find them below:
https://packages.debian.org/search?searchon=contents&keywords=pkg-config&mode=path&suite=stable&arch=any
What about the below?
diff --git a/tools/testing/selftests/bpf/Makefile
b/tools/testing/selftests/bpf/Makefile
index 4225f975fce3..62166d2f937d 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -29,13 +29,17 @@ SAN_CFLAGS ?=
SAN_LDFLAGS ?= $(SAN_CFLAGS)
RELEASE ?=
OPT_FLAGS ?= $(if $(RELEASE),-O2,-O0)
+
+LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
+LIBELF_LIBS := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null
|| echo -lelf)
Having dedicated variables and checking --cflags are a good idea.
