bpftool builds a bootstrap libbpf with HOSTCC, but the libbpf submake can still inherit target build flags through CFLAGS. This can break cross builds when host objects are compiled with target-only options.
Since HOST_CFLAGS contains warning options that are not suitable for building libbpf, use LIBBPF_BOOTSTRAP_CFLAGS with the warning options removed to build the bootstrap libbpf. Clear EXTRA_CFLAGS so target extra flags are not mixed into the host bootstrap libbpf build. Signed-off-by: Leo Yan <[email protected]> --- tools/bpf/bpftool/Makefile | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index 0febf60e1b64656035dfe93cd15cba090015587a..1f033e578f90a2d6b93168ab41399de758bdf659 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -47,7 +47,8 @@ $(LIBBPF_INTERNAL_HDRS): $(LIBBPF_HDRS_DIR)/%.h: $(BPF_DIR)/%.h | $(LIBBPF_HDRS_ $(LIBBPF_BOOTSTRAP): $(wildcard $(BPF_DIR)/*.[ch] $(BPF_DIR)/Makefile) | $(LIBBPF_BOOTSTRAP_OUTPUT) $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_BOOTSTRAP_OUTPUT) \ DESTDIR=$(LIBBPF_BOOTSTRAP_DESTDIR:/=) prefix= \ - ARCH= CROSS_COMPILE= CC="$(HOSTCC)" LD="$(HOSTLD)" AR="$(HOSTAR)" $@ install_headers + ARCH= CROSS_COMPILE= CC="$(HOSTCC)" LD="$(HOSTLD)" AR="$(HOSTAR)" \ + CFLAGS="$(LIBBPF_BOOTSTRAP_CFLAGS)" EXTRA_CFLAGS= $@ install_headers $(LIBBPF_BOOTSTRAP_INTERNAL_HDRS): $(LIBBPF_BOOTSTRAP_HDRS_DIR)/%.h: $(BPF_DIR)/%.h | $(LIBBPF_BOOTSTRAP_HDRS_DIR) $(call QUIET_INSTALL, $@) @@ -92,6 +93,9 @@ HOST_CFLAGS := $(subst -I$(LIBBPF_INCLUDE),-I$(LIBBPF_BOOTSTRAP_INCLUDE),\ $(subst $(CLANG_CROSS_FLAGS),,$(CFLAGS))) HOST_LDFLAGS := $(LDFLAGS) +# Remove warnings for libbpf bootstrap build +LIBBPF_BOOTSTRAP_CFLAGS := $(filter-out -W -Wall -Wextra -Wformat -Wformat-signedness,$(HOST_CFLAGS)) + INSTALL ?= install RM ?= rm -f -- 2.34.1
