On Mon, Nov 22, 2021 at 11:23 AM Jean-Philippe Brucker jean-philippe@linaro.org wrote:
Cross-building using clang requires passing the "-target" flag rather than using the CROSS_COMPILE prefix. Makefile.include transforms CROSS_COMPILE into CLANG_CROSS_FLAGS, and adds that to CFLAGS. Filter out the cross flags for the bootstrap bpftool, and erase the CROSS_COMPILE flag for the bootstrap libbpf.
Signed-off-by: Jean-Philippe Brucker jean-philippe@linaro.org
tools/bpf/bpftool/Makefile | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index 42eb8eee3d89..b0f3e17d981a 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -57,7 +57,7 @@ $(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=$(LIBBPF_BOOTSTRAP_DESTDIR) prefix= \
ARCH= CC=$(HOSTCC) LD=$(HOSTLD) $@ install_headers
ARCH= CROSS_COMPILE= CC=$(HOSTCC) LD=$(HOSTLD) $@ install_headers$(LIBBPF_BOOTSTRAP_INTERNAL_HDRS): $(LIBBPF_BOOTSTRAP_HDRS_DIR)/%.h: $(BPF_DIR)/%.h | $(LIBBPF_BOOTSTRAP_HDRS_DIR) $(call QUIET_INSTALL, $@) @@ -152,6 +152,9 @@ CFLAGS += -DHAVE_LIBBFD_SUPPORT SRCS += $(BFD_SRCS) endif
+HOST_CFLAGS = $(subst -I$(LIBBPF_INCLUDE),-I$(LIBBPF_BOOTSTRAP_INCLUDE),\
$(filter-out $(CLANG_CROSS_FLAGS),$(CFLAGS)))
Isn't this dangerous? CLANG_CROSS_FLAGS are treated as space-separated array of values, so if you have something like '-I whatever' it will actually filter out unrelated -Is from CFLAGS, no? I'd rather subst into empty string instead, just like we do for LIBBPF_INCLUDE.
BPFTOOL_BOOTSTRAP := $(BOOTSTRAP_OUTPUT)bpftool
BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o xlated_dumper.o btf_dumper.o disasm.o) @@ -202,7 +205,7 @@ endif CFLAGS += $(if $(BUILD_BPF_SKELS),,-DBPFTOOL_WITHOUT_SKELETONS)
$(BOOTSTRAP_OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c
$(QUIET_CC)$(HOSTCC) $(CFLAGS) -c -MMD $< -o $@
$(QUIET_CC)$(HOSTCC) $(HOST_CFLAGS) -c -MMD $< -o $@$(OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c $(QUIET_CC)$(CC) $(CFLAGS) -c -MMD $< -o $@ @@ -213,15 +216,13 @@ ifneq ($(feature-zlib), 1) endif
$(BPFTOOL_BOOTSTRAP): $(BOOTSTRAP_OBJS) $(LIBBPF_BOOTSTRAP)
$(QUIET_LINK)$(HOSTCC) $(CFLAGS) $(LDFLAGS) $(BOOTSTRAP_OBJS) $(LIBS_BOOTSTRAP) -o $@
$(QUIET_LINK)$(HOSTCC) $(HOST_CFLAGS) $(LDFLAGS) $(BOOTSTRAP_OBJS) $(LIBS_BOOTSTRAP) -o $@$(OUTPUT)bpftool: $(OBJS) $(LIBBPF) $(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $(OBJS) $(LIBS) -o $@
$(BOOTSTRAP_OUTPUT)%.o: %.c $(LIBBPF_BOOTSTRAP_INTERNAL_HDRS) | $(BOOTSTRAP_OUTPUT)
$(QUIET_CC)$(HOSTCC) \$(subst -I$(LIBBPF_INCLUDE),-I$(LIBBPF_BOOTSTRAP_INCLUDE),$(CFLAGS)) \-c -MMD $< -o $@
$(QUIET_CC)$(HOSTCC) $(HOST_CFLAGS) -c -MMD $< -o $@$(OUTPUT)%.o: %.c $(QUIET_CC)$(CC) $(CFLAGS) -c -MMD $< -o $@ -- 2.33.1