On Wed, Jul 6, 2022 at 10:13 AM James Hilliard <james.hilliard1@xxxxxxxxx> wrote: > > Note I'm testing with the following patches: > https://lore.kernel.org/bpf/20220706111839.1247911-1-james.hilliard1@xxxxxxxxx/ > https://lore.kernel.org/bpf/20220706140623.2917858-1-james.hilliard1@xxxxxxxxx/ > > It would appear there's some compatibility issues with bpftool gen and > GCC, not sure what side though is wrong here: > /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool > gen object src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o > src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.unstripped.o > libbpf: failed to find BTF info for global/extern symbol 'sd_restrictif_i' > Error: failed to link > 'src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.unstripped.o': > Unknown error -2 (-2) > > Relevant difference seems to be this: > GCC: > [55] FUNC 'sd_restrictif_i' type_id=47 linkage=static > Clang: > [27] FUNC 'sd_restrictif_i' type_id=26 linkage=global > GCC is wrong, clearly. This function is global ([0]) and libbpf expects it to be marked as such in BTF. https://github.com/systemd/systemd/blob/main/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.c#L42-L50 > GCC: > > [1] INT 'signed char' size=1 bits_offset=0 nr_bits=8 encoding=UNKN > [2] INT 'unsigned char' size=1 bits_offset=0 nr_bits=8 encoding=CHAR > [3] TYPEDEF '__u8' type_id=2 > [4] CONST '(anon)' type_id=3 [...]
