path: root/samples
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authorJakub Kicinski <>2019-06-05 16:47:22 -0700
committerDaniel Borkmann <>2019-06-06 02:15:14 +0200
commit07c3bbdb1a9b2046631a2a2950a0c16e10cfcab3 (patch)
treed00d4c0e183e8d2bec44f7c88e745349f394fc97 /samples
parent6685699e4ef5e9903d5c8bc6c2e6e13b931c98e1 (diff)
samples: bpf: print a warning about headers_install
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 <> Reviewed-by: Quentin Monnet <> Acked-by: Martin KaFai Lau <> Signed-off-by: Daniel Borkmann <>
Diffstat (limited to 'samples')
1 files changed, 9 insertions, 0 deletions
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
+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).)
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')