Re: Build error of samples/bpf

[Jiri Olsa <olsajiri@gmail.com>]

On Fri, Jul 15, 2022 at 03:54:42AM +0000, Zeng, Oak wrote:

SNIP

> > >   CC  samples/bpf/xdp_router_ipv4_user.o
> > >   CC  samples/bpf/xdp_rxq_info_user.o
> > >   CC  samples/bpf/xdp_sample_pkts_user.o
> > >   CC  samples/bpf/xdp_tx_iptunnel_user.o
> > >   CC  samples/bpf/xdpsock_ctrl_proc.o
> > >   CC  samples/bpf/xsk_fwd.o
> > >   CLANG-BPF  samples/bpf/xdp_sample.bpf.o
> > >   CLANG-BPF  samples/bpf/xdp_redirect_map_multi.bpf.o
> > >   CLANG-BPF  samples/bpf/xdp_redirect_cpu.bpf.o
> > >   CLANG-BPF  samples/bpf/xdp_redirect_map.bpf.o
> > >   CLANG-BPF  samples/bpf/xdp_monitor.bpf.o
> > >   CLANG-BPF  samples/bpf/xdp_redirect.bpf.o
> > >   BPF GEN-OBJ  samples/bpf/xdp_monitor
> > >   BPF GEN-SKEL samples/bpf/xdp_monitor
> > > libbpf: map 'rx_cnt': unexpected def kind var.
> > 
> > IIRC, this error is due to older clang. Can you try with a newer clang
> > (11 and above)?
> 
> Thank you Kumar.
> 
> I updated to llvm/clang to version 12, the issue persists. 
> 
> I also have another problem... To build those xdp samples, I need to enable CONFIG_DEBUG_INFO_BTF. But once this is enabled, I failed to build linux kernel with below errors. I was able to build on a 4.15 ubuntu machine but on a 5.11  ubuntu machine, I had below error to build the same kernel. Any one can give me some hint? I searched google but didn't figure out. I noticed somethings is killed during build of .bpf.vmlinux.bin.o, so I guess some of my tools is not updated?
> 
> 
> 
> szeng@szeng-develop:~/dii-tools/linux$ make -j$(nproc)
>   DESCEND objtool
>   DESCEND bpf/resolve_btfids
>   CALL    scripts/atomic/check-atomics.sh
>   CALL    scripts/checksyscalls.sh
>   CHK     include/generated/compile.h
>   UPD     include/generated/compile.h
>   CC      init/version.o
>   AR      init/built-in.a
>   CHK     kernel/kheaders_data.tar.xz
>   GEN     .version
>   CHK     include/generated/compile.h
>   UPD     include/generated/compile.h
>   CC      init/version.o
>   AR      init/built-in.a
>   LD      vmlinux.o
>   MODPOST vmlinux.symvers
>   MODINFO modules.builtin.modinfo
>   GEN     modules.builtin
>   LD      .tmp_vmlinux.btf
>   BTF     .btf.vmlinux.bin.o
> Killed

looks like something happened during BTF generation and that's
probably the reason why 'BTFIDS' is failing below

I'd double check with V=1 and if it's pahole that's killed,
I'd check that you can run it properly.. maybe some library
mismatch? or try to build and install the latest pahole

there was similar issue recently:
  https://lore.kernel.org/bpf/CAJQ9wQ-0UUAqzyB5P9Xy_0=hpxg9m+2OEzAmk2nWnoX9es9Gnw@mail.gmail.com/T/#t

jira


>   LD      .tmp_vmlinux.kallsyms1
>   KSYMS   .tmp_vmlinux.kallsyms1.S
>   AS      .tmp_vmlinux.kallsyms1.S
>   LD      .tmp_vmlinux.kallsyms2
>   KSYMS   .tmp_vmlinux.kallsyms2.S
>   AS      .tmp_vmlinux.kallsyms2.S
>   LD      vmlinux
>   BTFIDS  vmlinux
> FAILED: load BTF from vmlinux: No such file or directory
> make: *** [Makefile:1183: vmlinux] Error 255
> make: *** Deleting file 'vmlinux'
> 
> 
> Thanks,
> Oak
> 
> > 
> > > Error: failed to open BPF object file: Invalid argument
> > > samples/bpf/Makefile:430: recipe for target
> > 'samples/bpf/xdp_monitor.skel.h' failed
> > > make[1]: *** [samples/bpf/xdp_monitor.skel.h] Error 255
> > > make[1]: *** Deleting file 'samples/bpf/xdp_monitor.skel.h'
> > > Makefile:1868: recipe for target 'samples/bpf' failed
> > > make: *** [samples/bpf] Error 2
> > >
> > >
> > > Thanks,
> > > Oak
> > >