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authorQuentin Monnet <quentin@isovalent.com>2021-10-06 12:10:49 +0100
committerAndrii Nakryiko <andrii@kernel.org>2021-10-06 12:34:02 -0700
commit929bef467771d4d5a22b9edb51a2025dc0e49113 (patch)
treee33de0738babed1771644a310480924107c8efdc /samples/bpf/Makefile
parent90982e13561e0d8df91d49658d3bf068ae9f2dff (diff)
bpf: Use $(pound) instead of \# in Makefiles
Recent-ish versions of make do no longer consider number signs ("#") as comment symbols when they are inserted inside of a macro reference or in a function invocation. In such cases, the symbols should not be escaped. There are a few occurrences of "\#" in libbpf's and samples' Makefiles. In the former, the backslash is harmless, because grep associates no particular meaning to the escaped symbol and reads it as a regular "#". In samples' Makefile, recent versions of make will pass the backslash down to the compiler, making the probe fail all the time and resulting in the display of a warning about "make headers_install" being required, even after headers have been installed. A similar issue has been addressed at some other locations by commit 9564a8cf422d ("Kbuild: fix # escaping in .cmd files for future Make"). Let's address it for libbpf's and samples' Makefiles in the same fashion, by using a "$(pound)" variable (pulled from tools/scripts/Makefile.include for libbpf, or re-defined for the samples). Reference for the change in make: https://git.savannah.gnu.org/cgit/make.git/commit/?id=c6966b323811c37acedff05b57 Fixes: 2f3830412786 ("libbpf: Make libbpf_version.h non-auto-generated") Fixes: 07c3bbdb1a9b ("samples: bpf: print a warning about headers_install") Signed-off-by: Quentin Monnet <quentin@isovalent.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20211006111049.20708-1-quentin@isovalent.com
Diffstat (limited to 'samples/bpf/Makefile')
-rw-r--r--samples/bpf/Makefile4
1 files changed, 3 insertions, 1 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 4dc20be5fb96..a5783749ec15 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -3,6 +3,8 @@
BPF_SAMPLES_PATH ?= $(abspath $(srctree)/$(src))
TOOLS_PATH := $(BPF_SAMPLES_PATH)/../../tools
+pound := \#
+
# List of programs to build
tprogs-y := test_lru_dist
tprogs-y += sock_example
@@ -232,7 +234,7 @@ endif
# Don't evaluate probes and warnings if we need to run make recursively
ifneq ($(src),)
-HDR_PROBE := $(shell printf "\#include <linux/types.h>\n struct list_head { int a; }; int main() { return 0; }" | \
+HDR_PROBE := $(shell printf "$(pound)include <linux/types.h>\n struct list_head { int a; }; int main() { return 0; }" | \
$(CC) $(TPROGS_CFLAGS) $(TPROGS_LDFLAGS) -x c - \
-o /dev/null 2>/dev/null && echo okay)