On Wed, Nov 27, 2019 at 8:14 AM Stanislav Fomichev [off-list ref] wrote:

If vmlinux BTF generation fails, but CONFIG_DEBUG_INFO_BTF is set,
.BTF section of vmlinux is empty and kernel will prohibit
BPF loading and return "in-kernel BTF is malformed".

--dump-section argument to binutils' objcopy was added in version 2.25.
When using pre-2.25 binutils, BTF generation silently fails. Convert
to --only-section which is present on pre-2.25 binutils.

Documentation/process/changes.rst states that binutils 2.21+
is supported, not sure those standards apply to BPF subsystem.

v2:
* exit and print an error if gen_btf fails (John Fastabend)

v3:
* resend with Andrii's Acked-by/Tested-by tags

Cc: Andrii Nakryiko <redacted>
Cc: John Fastabend <john.fastabend@gmail.com>
Fixes: 341dfcf8d78ea ("btf: expose BTF info through sysfs")
Acked-by: Andrii Nakryiko <redacted>
Tested-by: Andrii Nakryiko <redacted>
Signed-off-by: Stanislav Fomichev <redacted>

Applied. Thanks