> Hello, I use gcc 12.1.0 to compile a source file:
> t.c
> struct t {
> int a:2;
> int b:3;
> int c:2;
> } g;
> with gcc -c -gbtf t.c
> and try to use libbpf API btf__parse_split, bpf_object__open, and
> bpf_object__open to parse and load into the kernel, but it failed with
> "libbpf: elf: /path/to/t.o is not a valid eBPF object file".
>
> Is it wrong for me to do so? Due to some constraint, I cannot use
> clang but gcc. How to parse and load gcc compiled object file with
> libbpf?
It seems to me that you are most likely using a GCC targetted at your
local architecture (x86_64-linux-gnu perhaps?) instead of
bpf-unknown-none.
(Note that GCC can generate BTF for any target, not just BPF.)
So you need a bpf-unknown-none-gcc toolchain.
You can either:
a) Install a pre-compiled cross available in your distro.
Debian ships gcc-bpf, for example. See
https://gcc.gnu.org/wiki/BPFBackEnd for a list.
or,
b) Build crossed versions of binutils and gcc, configuring with
--target=bpf-unknown-none.
or,
c) Use crosstool-ng to build a GCC BPF cross. We recently added support
for bpf-unknown-none there.
Hope this helps.
