On Tue, Dec 15, 2020 at 10:20 AM Kamal Mostafa wrote:
>
> If Makefile cannot find any of the vmlinux's in its VMLINUX_BTF_PATHS list,
> it tries to run btftool incorrectly, with VMLINUX_BTF unset:
>
> bpftool btf dump file $(VMLINUX_BTF) format c
>
> Such that the keyword 'format' is misinterpreted as the path to vmlinux.
> The resulting build error message is fairly cryptic:
>
> GEN vmlinux.h
> Error: failed to load BTF from format: No such file or directory
>
> This patch makes the failure reason clearer by yielding this instead:
>
> Makefile:...: *** cannot find a vmlinux for VMLINUX_BTF at any of
> "{paths}". Stop.
>
> Fixes: acbd06206bbb ("selftests/bpf: Add vmlinux.h selftest exercising
> tracing of syscalls")
> Cc: sta...@vger.kernel.org # 5.7+
> Signed-off-by: Kamal Mostafa
> ---
Applied to bpf tree, thanks. This conflicted with a67079b03165
("selftests/bpf: fix bpf_testmod.ko recompilation logic"), I resolved
the conflict and capitalized "Cannot" in the error message.
>
> [v2] moves the check to right after the VMLINUX_BTF definition.
>
> tools/testing/selftests/bpf/Makefile | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/Makefile
> b/tools/testing/selftests/bpf/Makefile
> index 542768f5195b..7ba631f495f7 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -146,6 +146,9 @@ VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux)
> \
> /sys/kernel/btf/vmlinux\
> /boot/vmlinux-$(shell uname -r)
> VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS
> +ifeq ($(VMLINUX_BTF),)
> +$(error cannot find a vmlinux for VMLINUX_BTF at any of
> "$(VMLINUX_BTF_PATHS)")
> +endif
>
> DEFAULT_BPFTOOL := $(SCRATCH_DIR)/sbin/bpftool
>
> --
> 2.17.1
>
