Commit be79505caf3f ("tools/runqslower: Install libbpf headers when
building") uses the target libbpf to build the host bpftool, which
doesn't work when cross-building:
make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -C tools/bpf/runqslower O=/tmp/runqslower
...
LINK /tmp/runqslower/bpftool/bpftool
/usr/bin/ld: /tmp/runqslower/libbpf/libbpf.a(libbpf-in.o): Relocations in generic ELF (EM: 183)
/usr/bin/ld: /tmp/runqslower/libbpf/libbpf.a: error adding symbols: file in wrong format
collect2: error: ld returned 1 exit status
When cross-building, the target architecture differs from the host. The
bpftool used for building runqslower is executed on the host, and thus
must use a different libbpf than that used for runqslower itself.
Remove the LIBBPF_OUTPUT and LIBBPF_DESTDIR parameters, so the bpftool
build makes its own library if necessary.
In the selftests, pass the host bpftool, already a prerequisite for the
runqslower recipe, as BPFTOOL_OUTPUT. The runqslower Makefile will use
the bpftool that's already built for selftests instead of making a new
one.
Fixes: be79505caf3f ("tools/runqslower: Install libbpf headers when building")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
---
tools/bpf/runqslower/Makefile | 3 +--
tools/testing/selftests/bpf/Makefile | 2 +-
2 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/tools/bpf/runqslower/Makefile b/tools/bpf/runqslower/Makefile
index bbd1150578f7..8791d0e2762b 100644
--- a/tools/bpf/runqslower/Makefile
+++ b/tools/bpf/runqslower/Makefile
@@ -88,5 +88,4 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(BPFOBJ_OU
$(DEFAULT_BPFTOOL): $(BPFOBJ) | $(BPFTOOL_OUTPUT)
$(Q)$(MAKE) $(submake_extras) -C ../bpftool OUTPUT=$(BPFTOOL_OUTPUT) \
- LIBBPF_OUTPUT=$(BPFOBJ_OUTPUT) \
- LIBBPF_DESTDIR=$(BPF_DESTDIR) CC=$(HOSTCC) LD=$(HOSTLD)
+ CC=$(HOSTCC) LD=$(HOSTLD)
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 54b0a41a3775..62fafbeb4672 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -187,7 +187,7 @@ DEFAULT_BPFTOOL := $(HOST_SCRATCH_DIR)/sbin/bpftool
$(OUTPUT)/runqslower: $(BPFOBJ) | $(DEFAULT_BPFTOOL) $(RUNQSLOWER_OUTPUT)
$(Q)$(MAKE) $(submake_extras) -C $(TOOLSDIR)/bpf/runqslower \
OUTPUT=$(RUNQSLOWER_OUTPUT) VMLINUX_BTF=$(VMLINUX_BTF) \
- BPFTOOL_OUTPUT=$(BUILD_DIR)/bpftool/ \
+ BPFTOOL_OUTPUT=$(HOST_BUILD_DIR)/bpftool/ \
BPFOBJ_OUTPUT=$(BUILD_DIR)/libbpf \
BPFOBJ=$(BPFOBJ) BPF_INCLUDE=$(INCLUDE_DIR) && \
cp $(RUNQSLOWER_OUTPUT)runqslower $@
--
2.33.1
