On Fri, Nov 12, 2021 at 04:17:21PM +0000, Quentin Monnet wrote:
2021-11-12 15:51 UTC+0000 ~ Jean-Philippe Brucker jean-philippe@linaro.org
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@linaro.org
Reviewed-by: Quentin Monnet quentin@isovalent.com
I realised too late I should have cc-ed you on those patches, apologies for not doing so. Thank you for the fix!
No worries, I usually try to catch build issues in bpf-next but missed it this time. I'm still slowly working towards getting automated testing on Arm targets, which will catch regressions quicker.
Thanks, Jean