It seems like periodically someone posts patches to "fix"
header includes. The issue is that samples expect the
include path to have the uAPI headers (from usr/) first,
and then tools/ headers, so that locally installed uAPI
headers take precedence. This means that if users didn't
run headers_install they will see all sort of strange
compilation errors, e.g.:
HOSTCC samples/bpf/test_lru_dist
samples/bpf/test_lru_dist.c:39:8: error: redefinition of ‘struct list_head’
struct list_head {
^~~~~~~~~
In file included from samples/bpf/test_lru_dist.c:9:0:
../tools/include/linux/types.h:69:8: note: originally defined here
struct list_head {
^~~~~~~~~
Try to detect this situation, and print a helpful warning.
v2: just use HOSTCC (Jiong).
Signed-off-by: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
Reviewed-by: Quentin Monnet <quentin.monnet@xxxxxxxxxxxxx>
---
samples/bpf/Makefile | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 253e5a2856be..4074a66a70ca 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -206,6 +206,15 @@ HOSTCC = $(CROSS_COMPILE)gcc
CLANG_ARCH_ARGS = -target $(ARCH)
endif
+HDR_PROBE := $(shell echo "\#include <linux/types.h>\n struct list_head { int a; }; int main() { return 0; }" | \
+ $(HOSTCC) $(KBUILD_HOSTCFLAGS) -x c - -o /dev/null 2>/dev/null && \
+ echo okay)
+
+ifeq ($(HDR_PROBE),)
+$(warning WARNING: Detected possible issues with include path.)
+$(warning WARNING: Please install kernel headers locally (make headers_install).)
+endif
+
BTF_LLC_PROBE := $(shell $(LLC) -march=bpf -mattr=help 2>&1 | grep dwarfris)
BTF_PAHOLE_PROBE := $(shell $(BTF_PAHOLE) --help 2>&1 | grep BTF)
BTF_OBJCOPY_PROBE := $(shell $(LLVM_OBJCOPY) --help 2>&1 | grep -i 'usage.*llvm')
--
2.21.0
