Build error of samples/bpf

Build error of samples/bpf

[Zeng, Oak]

Hello all,

I tried to build the latest samples/bpf following instructions in the README.rst in samples/bpf folder. I ran into various issue such as:

samples/bpf/Makefile:375: *** Cannot find a vmlinux for VMLINUX_BTF at any of "  /home/szeng/dii-tools/linux/vmlinux", build the kernel or set VMLINUX_BTF or VMLINUX_H variable

I was able to fix above issue by enable CONFIG_DEBUG_INFO_BTF in kernel .config file. 

But I eventually ran into other errors.  I had to fix those errors by install dwarves, updating my clang/llvm to version 10. 

I was able to build it if I comment out all the xdp programs from Makefile. It seems those xdp programs require advanced features such as data structure layout in vmlinux.h (dumped from vmlinux using bpftool) and this require special kernel config support.

So I thought instead of fixing those errors one by one, I should ask those who are working in this area, is there any instructions on how to build samples/bpf? The README.rst seems out-of-date, for example, it doesn't mention CONFIG_DEBUG_INFO_BTF. The required llvm/clang version in README.rst is also out-of-date.

More specifically, to build samples/bpf, is there an example kernel .config to use? I tried those config here https://github.com/torvalds/linux/blob/master/tools/testing/selftests/bpf/config but build errors persist.

Or is there any other tools I need to install/update on my system?

My whole build log is as below:

szeng@linux:~/dii-tools/linux$ make M=samples/bpf
readelf: Error: Missing knowledge of 32-bit reloc types used in DWARF sections of machine number 247
readelf: Warning: unable to apply unsupported reloc type 10 to section .debug_info
readelf: Warning: unable to apply unsupported reloc type 1 to section .debug_info
readelf: Warning: unable to apply unsupported reloc type 10 to section .debug_info make -C /home/szeng/dii-tools/linux/samples/bpf/../../tools/lib/bpf RM='rm -rf' EXTRA_CFLAGS="-Wall -O2 -Wmissing-prototypes -Wstrict-prototypes -I./usr/include -I./tools/testing/selftests/bpf/ -I/home/szeng/dii-tools/linux/samples/bpf/libbpf/include -I./tools/include -I./tools/perf -DHAVE_ATTR_TEST=0" \
        LDFLAGS= srctree=/home/szeng/dii-tools/linux/samples/bpf/../../ \
        O= OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/libbpf/ DESTDIR=/home/szeng/dii-tools/linux/samples/bpf/libbpf prefix= \
        /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a install_headers
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/nlattr.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_errno.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/str_error.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/netlink.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf_prog_linfo.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_probes.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/xsk.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/hashmap.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf_dump.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/ringbuf.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/strset.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/linker.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/gen_loader.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/relo_core.o
  LD      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf-in.o
  LINK    /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
  INSTALL headers
  CC  samples/bpf/test_lru_dist
  CC  samples/bpf/sock_example
  CC  samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.o
  CC  samples/bpf/../../tools/testing/selftests/bpf/trace_helpers.o
  CC  samples/bpf/cookie_uid_helper_example.o
  CC  samples/bpf/cpustat_user.o
  CC  samples/bpf/fds_example.o
  CC  samples/bpf/hbm.o
  CC  samples/bpf/i915_latency_hist_user.o
  CC  samples/bpf/i915_stat_user.o
  CC  samples/bpf/ibumad_user.o
  CC  samples/bpf/lathist_user.o
  CC  samples/bpf/lwt_len_hist_user.o
  CC  samples/bpf/map_perf_test_user.o
  CC  samples/bpf/offwaketime_user.o
  CC  samples/bpf/sampleip_user.o
  CC  samples/bpf/sockex1_user.o
  CC  samples/bpf/sockex2_user.o
  CC  samples/bpf/sockex3_user.o
  CC  samples/bpf/spintest_user.o
  CC  samples/bpf/syscall_tp_user.o
  CC  samples/bpf/task_fd_query_user.o
  CC  samples/bpf/tc_l2_redirect_user.o
  CC  samples/bpf/test_cgrp2_array_pin.o
  CC  samples/bpf/test_cgrp2_attach.o
  CC  samples/bpf/test_cgrp2_sock.o
  CC  samples/bpf/test_cgrp2_sock2.o
  CC  samples/bpf/test_current_task_under_cgroup_user.o
  CC  samples/bpf/test_map_in_map_user.o
  CC  samples/bpf/test_overhead_user.o
  CC  samples/bpf/test_probe_write_user_user.o
  CC  samples/bpf/trace_event_user.o
  CC  samples/bpf/trace_output_user.o
  CC  samples/bpf/tracex1_user.o
  CC  samples/bpf/tracex2_user.o
  CC  samples/bpf/tracex3_user.o
  CC  samples/bpf/tracex4_user.o
  CC  samples/bpf/tracex5_user.o
  CC  samples/bpf/tracex6_user.o
  CC  samples/bpf/tracex7_user.o
  CC  samples/bpf/xdp1_user.o
  CC  samples/bpf/xdp_adjust_tail_user.o
  CC  samples/bpf/xdp_fwd_user.o
make -C /home/szeng/dii-tools/linux/samples/bpf/../../tools/bpf/bpftool srctree=/home/szeng/dii-tools/linux/samples/bpf/../../ \
        OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/bpftool/ \
        LIBBPF_OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/libbpf/ \
        LIBBPF_DESTDIR=/home/szeng/dii-tools/linux/samples/bpf/libbpf/

Auto-detecting system features:
...                        libbfd: [ OFF ]
...        disassembler-four-args: [ OFF ]
...                          zlib: [ on  ]
...                        libcap: [ OFF ]
...               clang-bpf-co-re: [ on  ]


  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/nlattr.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_errno.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/str_error.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/netlink.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf_prog_linfo.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_probes.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/xsk.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/hashmap.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf_dump.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/ringbuf.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/strset.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/linker.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/gen_loader.o
  CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/relo_core.o
  LD      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf-in.o
  LINK    /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
  CLANG   /home/szeng/dii-tools/linux/samples/bpf/bpftool/profiler.bpf.o
  GEN     /home/szeng/dii-tools/linux/samples/bpf/bpftool/profiler.skel.h
  CC      /home/szeng/dii-tools/linux/samples/bpf/bpftool/prog.o
  CLANG   /home/szeng/dii-tools/linux/samples/bpf/bpftool/pid_iter.bpf.o
  GEN     /home/szeng/dii-tools/linux/samples/bpf/bpftool/pid_iter.skel.h
  CC      /home/szeng/dii-tools/linux/samples/bpf/bpftool/pids.o
  LINK    /home/szeng/dii-tools/linux/samples/bpf/bpftool/bpftool
  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.
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

Re: Build error of samples/bpf

[sdf]

On 07/12, Zeng, Oak wrote:
> Hello all,

> I tried to build the latest samples/bpf following instructions in the  
> README.rst in samples/bpf folder. I ran into various issue such as:

> samples/bpf/Makefile:375: *** Cannot find a vmlinux for VMLINUX_BTF at  
> any of "  /home/szeng/dii-tools/linux/vmlinux", build the kernel or set  
> VMLINUX_BTF or VMLINUX_H variable

> I was able to fix above issue by enable CONFIG_DEBUG_INFO_BTF in  
> kernel .config file.

> But I eventually ran into other errors.  I had to fix those errors by  
> install dwarves, updating my clang/llvm to version 10.

> I was able to build it if I comment out all the xdp programs from  
> Makefile. It seems those xdp programs require advanced features such as  
> data structure layout in vmlinux.h (dumped from vmlinux using bpftool)  
> and this require special kernel config support.

> So I thought instead of fixing those errors one by one, I should ask  
> those who are working in this area, is there any instructions on how to  
> build samples/bpf? The README.rst seems out-of-date, for example, it  
> doesn't mention CONFIG_DEBUG_INFO_BTF. The required llvm/clang version in  
> README.rst is also out-of-date.

> More specifically, to build samples/bpf, is there an example  
> kernel .config to use? I tried those config here  
> https://github.com/torvalds/linux/blob/master/tools/testing/selftests/bpf/config  
> but build errors persist.

> Or is there any other tools I need to install/update on my system?

In general, I'd say, samples/bpf tend to go stale. We mostly work on
the selftests and don't pay too much attention to the samples :-(
Ideally, the samples should be part of selftests so they get
exercised by the CI.

One thing I can suggest is to look at tools/testing/selftests/bpf/vmtest.sh
script. It builds the kernels with vetted configs capable of running
selftests. That should be, in theory, be enough to compile the samples.

> My whole build log is as below:

> szeng@linux:~/dii-tools/linux$ make M=samples/bpf
> readelf: Error: Missing knowledge of 32-bit reloc types used in DWARF  
> sections of machine number 247
> readelf: Warning: unable to apply unsupported reloc type 10 to  
> section .debug_info
> readelf: Warning: unable to apply unsupported reloc type 1 to  
> section .debug_info
> readelf: Warning: unable to apply unsupported reloc type 10 to  
> section .debug_info make -C  
> /home/szeng/dii-tools/linux/samples/bpf/../../tools/lib/bpf RM='rm -rf'  
> EXTRA_CFLAGS="-Wall -O2 -Wmissing-prototypes -Wstrict-prototypes  
> -I./usr/include -I./tools/testing/selftests/bpf/  
> -I/home/szeng/dii-tools/linux/samples/bpf/libbpf/include  
> -I./tools/include -I./tools/perf -DHAVE_ATTR_TEST=0" \
>          LDFLAGS= srctree=/home/szeng/dii-tools/linux/samples/bpf/../../ \
>          O= OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/libbpf/  
> DESTDIR=/home/szeng/dii-tools/linux/samples/bpf/libbpf prefix= \
>          /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a  
> install_headers
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf.o
>    CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/nlattr.o
>    CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_errno.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/str_error.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/netlink.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf_prog_linfo.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_probes.o
>    CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/xsk.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/hashmap.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf_dump.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/ringbuf.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/strset.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/linker.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/gen_loader.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/relo_core.o
>    LD       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf-in.o
>    LINK    /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
>    INSTALL headers
>    CC  samples/bpf/test_lru_dist
>    CC  samples/bpf/sock_example
>    CC  samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.o
>    CC  samples/bpf/../../tools/testing/selftests/bpf/trace_helpers.o
>    CC  samples/bpf/cookie_uid_helper_example.o
>    CC  samples/bpf/cpustat_user.o
>    CC  samples/bpf/fds_example.o
>    CC  samples/bpf/hbm.o
>    CC  samples/bpf/i915_latency_hist_user.o
>    CC  samples/bpf/i915_stat_user.o
>    CC  samples/bpf/ibumad_user.o
>    CC  samples/bpf/lathist_user.o
>    CC  samples/bpf/lwt_len_hist_user.o
>    CC  samples/bpf/map_perf_test_user.o
>    CC  samples/bpf/offwaketime_user.o
>    CC  samples/bpf/sampleip_user.o
>    CC  samples/bpf/sockex1_user.o
>    CC  samples/bpf/sockex2_user.o
>    CC  samples/bpf/sockex3_user.o
>    CC  samples/bpf/spintest_user.o
>    CC  samples/bpf/syscall_tp_user.o
>    CC  samples/bpf/task_fd_query_user.o
>    CC  samples/bpf/tc_l2_redirect_user.o
>    CC  samples/bpf/test_cgrp2_array_pin.o
>    CC  samples/bpf/test_cgrp2_attach.o
>    CC  samples/bpf/test_cgrp2_sock.o
>    CC  samples/bpf/test_cgrp2_sock2.o
>    CC  samples/bpf/test_current_task_under_cgroup_user.o
>    CC  samples/bpf/test_map_in_map_user.o
>    CC  samples/bpf/test_overhead_user.o
>    CC  samples/bpf/test_probe_write_user_user.o
>    CC  samples/bpf/trace_event_user.o
>    CC  samples/bpf/trace_output_user.o
>    CC  samples/bpf/tracex1_user.o
>    CC  samples/bpf/tracex2_user.o
>    CC  samples/bpf/tracex3_user.o
>    CC  samples/bpf/tracex4_user.o
>    CC  samples/bpf/tracex5_user.o
>    CC  samples/bpf/tracex6_user.o
>    CC  samples/bpf/tracex7_user.o
>    CC  samples/bpf/xdp1_user.o
>    CC  samples/bpf/xdp_adjust_tail_user.o
>    CC  samples/bpf/xdp_fwd_user.o
> make -C /home/szeng/dii-tools/linux/samples/bpf/../../tools/bpf/bpftool  
> srctree=/home/szeng/dii-tools/linux/samples/bpf/../../ \
>          OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/bpftool/ \
>          LIBBPF_OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/libbpf/ \
>          LIBBPF_DESTDIR=/home/szeng/dii-tools/linux/samples/bpf/libbpf/

> Auto-detecting system features:
> ...                        libbfd: [ OFF ]
> ...        disassembler-four-args: [ OFF ]
> ...                          zlib: [ on  ]
> ...                        libcap: [ OFF ]
> ...               clang-bpf-co-re: [ on  ]


>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf.o
>    CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/nlattr.o
>    CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_errno.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/str_error.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/netlink.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf_prog_linfo.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_probes.o
>    CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/xsk.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/hashmap.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf_dump.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/ringbuf.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/strset.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/linker.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/gen_loader.o
>    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/relo_core.o
>    LD       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf-in.o
>    LINK    /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
>    CLANG   /home/szeng/dii-tools/linux/samples/bpf/bpftool/profiler.bpf.o
>    GEN     /home/szeng/dii-tools/linux/samples/bpf/bpftool/profiler.skel.h
>    CC      /home/szeng/dii-tools/linux/samples/bpf/bpftool/prog.o
>    CLANG   /home/szeng/dii-tools/linux/samples/bpf/bpftool/pid_iter.bpf.o
>    GEN     /home/szeng/dii-tools/linux/samples/bpf/bpftool/pid_iter.skel.h
>    CC      /home/szeng/dii-tools/linux/samples/bpf/bpftool/pids.o
>    LINK    /home/szeng/dii-tools/linux/samples/bpf/bpftool/bpftool
>    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.
> 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

RE: Build error of samples/bpf

[Zeng, Oak]

Thank you sdf for the reply. 

It is news to me that samples/bpf tend to go stale. When I looked the samples/bpf folder git history, the last update is from only 2 months ago. And yes I can see samples/bfp is not actively updated recently. We are from Intel's GPU group and we are working on some bpf tools for GPU profiling purpose. We made our work based on the structure of samples/bpf because we can conveniently use libbpf. We chose bpf c frontend (vs python frontend) because python bpf program seems can't execute under non-root leading to some security concerns. This work is not yet upstream but we planned to upstream it.

Now if samples/bpf is going stale, we need to change our plan. Specifically I have a few questions for our future planning:

1. does bpf community accept more bpf samples such as using bpf to kprobe/tracepoint GPU activities? Is such work helpful/welcome to/by the community? I can see the existing samples and selftest are mainly for general linux profiling such as fs, network etc. Do you accept more samples for specific driver profiling - in our case it is profiling of Intel's i915 GPU driver.

2. Should we port our samples/bpf to tools/testing/selftests/bpf for upstream purpose? I am not sure whether tools/testing/selftests/bpf is a good place for our gpu profiling samples. If tools/testing/selftests/bpf is not a good place for gpu profilers, any suggestion where we can upstream our gpu profilers?

Cc other bpf reviewers. Thank you for your considerations!

Thanks,
Oak

> -----Original Message-----
> From: sdf@google.com <sdf@google.com>
> Sent: July 12, 2022 1:23 PM
> To: Zeng, Oak <oak.zeng@intel.com>
> Cc: bpf@vger.kernel.org
> Subject: Re: Build error of samples/bpf
> 
> On 07/12, Zeng, Oak wrote:
> > Hello all,
> 
> > I tried to build the latest samples/bpf following instructions in the
> > README.rst in samples/bpf folder. I ran into various issue such as:
> 
> > samples/bpf/Makefile:375: *** Cannot find a vmlinux for VMLINUX_BTF at
> > any of "  /home/szeng/dii-tools/linux/vmlinux", build the kernel or
> > set VMLINUX_BTF or VMLINUX_H variable
> 
> > I was able to fix above issue by enable CONFIG_DEBUG_INFO_BTF in
> > kernel .config file.
> 
> > But I eventually ran into other errors.  I had to fix those errors by
> > install dwarves, updating my clang/llvm to version 10.
> 
> > I was able to build it if I comment out all the xdp programs from
> > Makefile. It seems those xdp programs require advanced features such
> > as data structure layout in vmlinux.h (dumped from vmlinux using
> > bpftool) and this require special kernel config support.
> 
> > So I thought instead of fixing those errors one by one, I should ask
> > those who are working in this area, is there any instructions on how
> > to build samples/bpf? The README.rst seems out-of-date, for example,
> > it doesn't mention CONFIG_DEBUG_INFO_BTF. The required llvm/clang
> > version in README.rst is also out-of-date.
> 
> > More specifically, to build samples/bpf, is there an example kernel
> > .config to use? I tried those config here
> > https://github.com/torvalds/linux/blob/master/tools/testing/selftests/
> > bpf/config
> > but build errors persist.
> 
> > Or is there any other tools I need to install/update on my system?
> 
> In general, I'd say, samples/bpf tend to go stale. We mostly work on the
> selftests and don't pay too much attention to the samples :-( Ideally, the
> samples should be part of selftests so they get exercised by the CI.
> 
> One thing I can suggest is to look at tools/testing/selftests/bpf/vmtest.sh
> script. It builds the kernels with vetted configs capable of running selftests.
> That should be, in theory, be enough to compile the samples.
> 
> > My whole build log is as below:
> 
> > szeng@linux:~/dii-tools/linux$ make M=samples/bpf
> > readelf: Error: Missing knowledge of 32-bit reloc types used in DWARF
> > sections of machine number 247
> > readelf: Warning: unable to apply unsupported reloc type 10 to section
> > .debug_info
> > readelf: Warning: unable to apply unsupported reloc type 1 to section
> > .debug_info
> > readelf: Warning: unable to apply unsupported reloc type 10 to section
> > .debug_info make -C
> > /home/szeng/dii-tools/linux/samples/bpf/../../tools/lib/bpf RM='rm -rf'
> > EXTRA_CFLAGS="-Wall -O2 -Wmissing-prototypes -Wstrict-prototypes
> > -I./usr/include -I./tools/testing/selftests/bpf/
> > -I/home/szeng/dii-tools/linux/samples/bpf/libbpf/include
> > -I./tools/include -I./tools/perf -DHAVE_ATTR_TEST=0" \
> >          LDFLAGS= srctree=/home/szeng/dii-tools/linux/samples/bpf/../../ \
> >          O= OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/libbpf/
> > DESTDIR=/home/szeng/dii-tools/linux/samples/bpf/libbpf prefix= \
> >          /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
> > install_headers
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf.o
> >    CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/nlattr.o
> >    CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_errno.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/str_error.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/netlink.o
> >    CC
> > /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/bpf_prog_linfo.o
> >    CC
> > /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/libbpf_probes.o
> >    CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/xsk.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/hashmap.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf_dump.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/ringbuf.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/strset.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/linker.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/gen_loader.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/relo_core.o
> >    LD
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf-in.o
> >    LINK    /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
> >    INSTALL headers
> >    CC  samples/bpf/test_lru_dist
> >    CC  samples/bpf/sock_example
> >    CC  samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.o
> >    CC  samples/bpf/../../tools/testing/selftests/bpf/trace_helpers.o
> >    CC  samples/bpf/cookie_uid_helper_example.o
> >    CC  samples/bpf/cpustat_user.o
> >    CC  samples/bpf/fds_example.o
> >    CC  samples/bpf/hbm.o
> >    CC  samples/bpf/i915_latency_hist_user.o
> >    CC  samples/bpf/i915_stat_user.o
> >    CC  samples/bpf/ibumad_user.o
> >    CC  samples/bpf/lathist_user.o
> >    CC  samples/bpf/lwt_len_hist_user.o
> >    CC  samples/bpf/map_perf_test_user.o
> >    CC  samples/bpf/offwaketime_user.o
> >    CC  samples/bpf/sampleip_user.o
> >    CC  samples/bpf/sockex1_user.o
> >    CC  samples/bpf/sockex2_user.o
> >    CC  samples/bpf/sockex3_user.o
> >    CC  samples/bpf/spintest_user.o
> >    CC  samples/bpf/syscall_tp_user.o
> >    CC  samples/bpf/task_fd_query_user.o
> >    CC  samples/bpf/tc_l2_redirect_user.o
> >    CC  samples/bpf/test_cgrp2_array_pin.o
> >    CC  samples/bpf/test_cgrp2_attach.o
> >    CC  samples/bpf/test_cgrp2_sock.o
> >    CC  samples/bpf/test_cgrp2_sock2.o
> >    CC  samples/bpf/test_current_task_under_cgroup_user.o
> >    CC  samples/bpf/test_map_in_map_user.o
> >    CC  samples/bpf/test_overhead_user.o
> >    CC  samples/bpf/test_probe_write_user_user.o
> >    CC  samples/bpf/trace_event_user.o
> >    CC  samples/bpf/trace_output_user.o
> >    CC  samples/bpf/tracex1_user.o
> >    CC  samples/bpf/tracex2_user.o
> >    CC  samples/bpf/tracex3_user.o
> >    CC  samples/bpf/tracex4_user.o
> >    CC  samples/bpf/tracex5_user.o
> >    CC  samples/bpf/tracex6_user.o
> >    CC  samples/bpf/tracex7_user.o
> >    CC  samples/bpf/xdp1_user.o
> >    CC  samples/bpf/xdp_adjust_tail_user.o
> >    CC  samples/bpf/xdp_fwd_user.o
> > make -C
> > /home/szeng/dii-tools/linux/samples/bpf/../../tools/bpf/bpftool
> > srctree=/home/szeng/dii-tools/linux/samples/bpf/../../ \
> >          OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/bpftool/ \
> >          LIBBPF_OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/libbpf/ \
> >
> > LIBBPF_DESTDIR=/home/szeng/dii-tools/linux/samples/bpf/libbpf/
> 
> > Auto-detecting system features:
> > ...                        libbfd: [ OFF ]
> > ...        disassembler-four-args: [ OFF ]
> > ...                          zlib: [ on  ]
> > ...                        libcap: [ OFF ]
> > ...               clang-bpf-co-re: [ on  ]
> 
> 
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf.o
> >    CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/nlattr.o
> >    CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_errno.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/str_error.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/netlink.o
> >    CC
> > /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/bpf_prog_linfo.o
> >    CC
> > /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/libbpf_probes.o
> >    CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/xsk.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/hashmap.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf_dump.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/ringbuf.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/strset.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/linker.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/gen_loader.o
> >    CC
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/relo_core.o
> >    LD
> > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf-in.o
> >    LINK    /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
> >    CLANG   /home/szeng/dii-tools/linux/samples/bpf/bpftool/profiler.bpf.o
> >    GEN     /home/szeng/dii-tools/linux/samples/bpf/bpftool/profiler.skel.h
> >    CC      /home/szeng/dii-tools/linux/samples/bpf/bpftool/prog.o
> >    CLANG   /home/szeng/dii-tools/linux/samples/bpf/bpftool/pid_iter.bpf.o
> >    GEN     /home/szeng/dii-tools/linux/samples/bpf/bpftool/pid_iter.skel.h
> >    CC      /home/szeng/dii-tools/linux/samples/bpf/bpftool/pids.o
> >    LINK    /home/szeng/dii-tools/linux/samples/bpf/bpftool/bpftool
> >    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.
> > 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

Re: Build error of samples/bpf

[sdf]

On 07/13, Zeng, Oak wrote:
> Thank you sdf for the reply.

> It is news to me that samples/bpf tend to go stale. When I looked the  
> samples/bpf folder git history, the last update is from only 2 months  
> ago. And yes I can see samples/bfp is not actively updated recently. We  
> are from Intel's GPU group and we are working on some bpf tools for GPU  
> profiling purpose. We made our work based on the structure of samples/bpf  
> because we can conveniently use libbpf. We chose bpf c frontend (vs  
> python frontend) because python bpf program seems can't execute under  
> non-root leading to some security concerns. This work is not yet upstream  
> but we planned to upstream it.

I'm mostly talking from the following perspective:
http://vger.kernel.org/bpfconf2022_material/lsfmmbpf2022-bpf-ci.pdf

BPF maintainers have a CI that continuously builds and runs
tools/testing/selftests/bpf. I don't think it includes samples/bpf;
that's what I mean by "go stale". Eventually, people fix samples, but
there is no continuous system to verify they are healthy.

> Now if samples/bpf is going stale, we need to change our plan.  
> Specifically I have a few questions for our future planning:

> 1. does bpf community accept more bpf samples such as using bpf to  
> kprobe/tracepoint GPU activities? Is such work helpful/welcome to/by the  
> community? I can see the existing samples and selftest are mainly for  
> general linux profiling such as fs, network etc. Do you accept more  
> samples for specific driver profiling - in our case it is profiling of  
> Intel's i915 GPU driver.

> 2. Should we port our samples/bpf to tools/testing/selftests/bpf for  
> upstream purpose? I am not sure whether tools/testing/selftests/bpf is a  
> good place for our gpu profiling samples. If tools/testing/selftests/bpf  
> is not a good place for gpu profilers, any suggestion where we can  
> upstream our gpu profilers?

> Cc other bpf reviewers. Thank you for your considerations!

I'll let others chime in, but IMO it's a gray area. This can probably
go into samples, but if you want to have a profiler that you want others
to use, why not distribute it as part of real profiling tools like perf or
bpftrace?

> Thanks,
> Oak

> > -----Original Message-----
> > From: sdf@google.com <sdf@google.com>
> > Sent: July 12, 2022 1:23 PM
> > To: Zeng, Oak <oak.zeng@intel.com>
> > Cc: bpf@vger.kernel.org
> > Subject: Re: Build error of samples/bpf
> >
> > On 07/12, Zeng, Oak wrote:
> > > Hello all,
> >
> > > I tried to build the latest samples/bpf following instructions in the
> > > README.rst in samples/bpf folder. I ran into various issue such as:
> >
> > > samples/bpf/Makefile:375: *** Cannot find a vmlinux for VMLINUX_BTF at
> > > any of "  /home/szeng/dii-tools/linux/vmlinux", build the kernel or
> > > set VMLINUX_BTF or VMLINUX_H variable
> >
> > > I was able to fix above issue by enable CONFIG_DEBUG_INFO_BTF in
> > > kernel .config file.
> >
> > > But I eventually ran into other errors.  I had to fix those errors by
> > > install dwarves, updating my clang/llvm to version 10.
> >
> > > I was able to build it if I comment out all the xdp programs from
> > > Makefile. It seems those xdp programs require advanced features such
> > > as data structure layout in vmlinux.h (dumped from vmlinux using
> > > bpftool) and this require special kernel config support.
> >
> > > So I thought instead of fixing those errors one by one, I should ask
> > > those who are working in this area, is there any instructions on how
> > > to build samples/bpf? The README.rst seems out-of-date, for example,
> > > it doesn't mention CONFIG_DEBUG_INFO_BTF. The required llvm/clang
> > > version in README.rst is also out-of-date.
> >
> > > More specifically, to build samples/bpf, is there an example kernel
> > > .config to use? I tried those config here
> > > https://github.com/torvalds/linux/blob/master/tools/testing/selftests/
> > > bpf/config
> > > but build errors persist.
> >
> > > Or is there any other tools I need to install/update on my system?
> >
> > In general, I'd say, samples/bpf tend to go stale. We mostly work on the
> > selftests and don't pay too much attention to the samples :-( Ideally,  
> the
> > samples should be part of selftests so they get exercised by the CI.
> >
> > One thing I can suggest is to look at  
> tools/testing/selftests/bpf/vmtest.sh
> > script. It builds the kernels with vetted configs capable of running  
> selftests.
> > That should be, in theory, be enough to compile the samples.
> >
> > > My whole build log is as below:
> >
> > > szeng@linux:~/dii-tools/linux$ make M=samples/bpf
> > > readelf: Error: Missing knowledge of 32-bit reloc types used in DWARF
> > > sections of machine number 247
> > > readelf: Warning: unable to apply unsupported reloc type 10 to section
> > > .debug_info
> > > readelf: Warning: unable to apply unsupported reloc type 1 to section
> > > .debug_info
> > > readelf: Warning: unable to apply unsupported reloc type 10 to section
> > > .debug_info make -C
> > > /home/szeng/dii-tools/linux/samples/bpf/../../tools/lib/bpf RM='rm  
> -rf'
> > > EXTRA_CFLAGS="-Wall -O2 -Wmissing-prototypes -Wstrict-prototypes
> > > -I./usr/include -I./tools/testing/selftests/bpf/
> > > -I/home/szeng/dii-tools/linux/samples/bpf/libbpf/include
> > > -I./tools/include -I./tools/perf -DHAVE_ATTR_TEST=0" \
> > >          LDFLAGS=  
> srctree=/home/szeng/dii-tools/linux/samples/bpf/../../ \
> > >          O= OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/libbpf/
> > > DESTDIR=/home/szeng/dii-tools/linux/samples/bpf/libbpf prefix= \
> > >          /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
> > > install_headers
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf.o
> > >    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/nlattr.o
> > >    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf.o
> > >    CC
> > >  
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_errno.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/str_error.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/netlink.o
> > >    CC
> > > /home/szeng/dii-
> > tools/linux/samples/bpf/libbpf/staticobjs/bpf_prog_linfo.o
> > >    CC
> > > /home/szeng/dii-
> > tools/linux/samples/bpf/libbpf/staticobjs/libbpf_probes.o
> > >    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/xsk.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/hashmap.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf_dump.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/ringbuf.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/strset.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/linker.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/gen_loader.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/relo_core.o
> > >    LD
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf-in.o
> > >    LINK    /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
> > >    INSTALL headers
> > >    CC  samples/bpf/test_lru_dist
> > >    CC  samples/bpf/sock_example
> > >    CC  samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.o
> > >    CC  samples/bpf/../../tools/testing/selftests/bpf/trace_helpers.o
> > >    CC  samples/bpf/cookie_uid_helper_example.o
> > >    CC  samples/bpf/cpustat_user.o
> > >    CC  samples/bpf/fds_example.o
> > >    CC  samples/bpf/hbm.o
> > >    CC  samples/bpf/i915_latency_hist_user.o
> > >    CC  samples/bpf/i915_stat_user.o
> > >    CC  samples/bpf/ibumad_user.o
> > >    CC  samples/bpf/lathist_user.o
> > >    CC  samples/bpf/lwt_len_hist_user.o
> > >    CC  samples/bpf/map_perf_test_user.o
> > >    CC  samples/bpf/offwaketime_user.o
> > >    CC  samples/bpf/sampleip_user.o
> > >    CC  samples/bpf/sockex1_user.o
> > >    CC  samples/bpf/sockex2_user.o
> > >    CC  samples/bpf/sockex3_user.o
> > >    CC  samples/bpf/spintest_user.o
> > >    CC  samples/bpf/syscall_tp_user.o
> > >    CC  samples/bpf/task_fd_query_user.o
> > >    CC  samples/bpf/tc_l2_redirect_user.o
> > >    CC  samples/bpf/test_cgrp2_array_pin.o
> > >    CC  samples/bpf/test_cgrp2_attach.o
> > >    CC  samples/bpf/test_cgrp2_sock.o
> > >    CC  samples/bpf/test_cgrp2_sock2.o
> > >    CC  samples/bpf/test_current_task_under_cgroup_user.o
> > >    CC  samples/bpf/test_map_in_map_user.o
> > >    CC  samples/bpf/test_overhead_user.o
> > >    CC  samples/bpf/test_probe_write_user_user.o
> > >    CC  samples/bpf/trace_event_user.o
> > >    CC  samples/bpf/trace_output_user.o
> > >    CC  samples/bpf/tracex1_user.o
> > >    CC  samples/bpf/tracex2_user.o
> > >    CC  samples/bpf/tracex3_user.o
> > >    CC  samples/bpf/tracex4_user.o
> > >    CC  samples/bpf/tracex5_user.o
> > >    CC  samples/bpf/tracex6_user.o
> > >    CC  samples/bpf/tracex7_user.o
> > >    CC  samples/bpf/xdp1_user.o
> > >    CC  samples/bpf/xdp_adjust_tail_user.o
> > >    CC  samples/bpf/xdp_fwd_user.o
> > > make -C
> > > /home/szeng/dii-tools/linux/samples/bpf/../../tools/bpf/bpftool
> > > srctree=/home/szeng/dii-tools/linux/samples/bpf/../../ \
> > >          OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/bpftool/ \
> > >           
> LIBBPF_OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/libbpf/ \
> > >
> > > LIBBPF_DESTDIR=/home/szeng/dii-tools/linux/samples/bpf/libbpf/
> >
> > > Auto-detecting system features:
> > > ...                        libbfd: [ OFF ]
> > > ...        disassembler-four-args: [ OFF ]
> > > ...                          zlib: [ on  ]
> > > ...                        libcap: [ OFF ]
> > > ...               clang-bpf-co-re: [ on  ]
> >
> >
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf.o
> > >    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/nlattr.o
> > >    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf.o
> > >    CC
> > >  
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_errno.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/str_error.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/netlink.o
> > >    CC
> > > /home/szeng/dii-
> > tools/linux/samples/bpf/libbpf/staticobjs/bpf_prog_linfo.o
> > >    CC
> > > /home/szeng/dii-
> > tools/linux/samples/bpf/libbpf/staticobjs/libbpf_probes.o
> > >    CC       
> /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/xsk.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/hashmap.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf_dump.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/ringbuf.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/strset.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/linker.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/gen_loader.o
> > >    CC
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/relo_core.o
> > >    LD
> > > /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf-in.o
> > >    LINK    /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
> > >    CLANG    
> /home/szeng/dii-tools/linux/samples/bpf/bpftool/profiler.bpf.o
> > >    GEN      
> /home/szeng/dii-tools/linux/samples/bpf/bpftool/profiler.skel.h
> > >    CC      /home/szeng/dii-tools/linux/samples/bpf/bpftool/prog.o
> > >    CLANG    
> /home/szeng/dii-tools/linux/samples/bpf/bpftool/pid_iter.bpf.o
> > >    GEN      
> /home/szeng/dii-tools/linux/samples/bpf/bpftool/pid_iter.skel.h
> > >    CC      /home/szeng/dii-tools/linux/samples/bpf/bpftool/pids.o
> > >    LINK    /home/szeng/dii-tools/linux/samples/bpf/bpftool/bpftool
> > >    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.
> > > 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

Re: Build error of samples/bpf

[Daniel Müller]

On Wed, Jul 13, 2022 at 09:18:43AM -0700, sdf@google.com wrote:
> On 07/13, Zeng, Oak wrote:
> > Thank you sdf for the reply.
> 
> > It is news to me that samples/bpf tend to go stale. When I looked the
> > samples/bpf folder git history, the last update is from only 2 months
> > ago. And yes I can see samples/bfp is not actively updated recently. We
> > are from Intel's GPU group and we are working on some bpf tools for GPU
> > profiling purpose. We made our work based on the structure of
> > samples/bpf because we can conveniently use libbpf. We chose bpf c
> > frontend (vs python frontend) because python bpf program seems can't
> > execute under non-root leading to some security concerns. This work is
> > not yet upstream but we planned to upstream it.
> 
> I'm mostly talking from the following perspective:
> http://vger.kernel.org/bpfconf2022_material/lsfmmbpf2022-bpf-ci.pdf
> 
> BPF maintainers have a CI that continuously builds and runs
> tools/testing/selftests/bpf. I don't think it includes samples/bpf;
> that's what I mean by "go stale". Eventually, people fix samples, but
> there is no continuous system to verify they are healthy.

I am looking into some aspects of the CI. I will see what it would take to
build and/or test samples/bpf in an automated fashion there.

[...]

Thanks,
Daniel

Re: Build error of samples/bpf

[Daniel Müller]

On Wed, Jul 13, 2022 at 08:18:10PM +0000, Daniel Müller wrote:
> On Wed, Jul 13, 2022 at 09:18:43AM -0700, sdf@google.com wrote:
> > On 07/13, Zeng, Oak wrote:
> > > Thank you sdf for the reply.
> > 
> > > It is news to me that samples/bpf tend to go stale. When I looked the
> > > samples/bpf folder git history, the last update is from only 2 months
> > > ago. And yes I can see samples/bfp is not actively updated recently. We
> > > are from Intel's GPU group and we are working on some bpf tools for GPU
> > > profiling purpose. We made our work based on the structure of
> > > samples/bpf because we can conveniently use libbpf. We chose bpf c
> > > frontend (vs python frontend) because python bpf program seems can't
> > > execute under non-root leading to some security concerns. This work is
> > > not yet upstream but we planned to upstream it.
> > 
> > I'm mostly talking from the following perspective:
> > http://vger.kernel.org/bpfconf2022_material/lsfmmbpf2022-bpf-ci.pdf
> > 
> > BPF maintainers have a CI that continuously builds and runs
> > tools/testing/selftests/bpf. I don't think it includes samples/bpf;
> > that's what I mean by "go stale". Eventually, people fix samples, but
> > there is no continuous system to verify they are healthy.
> 
> I am looking into some aspects of the CI. I will see what it would take to
> build and/or test samples/bpf in an automated fashion there.

For what it's worth, we now [0] have samples/bpf built in BPF CI. Here is an
example run: https://github.com/kernel-patches/bpf/runs/7527372083 (it may not
be possible for folks not part of the organization to see detailed logs, but you
should be able to see the "Build samples" step)

Thanks,
Daniel

[0] https://github.com/kernel-patches/vmtest/pull/98

Re: Build error of samples/bpf

[Andrii Nakryiko]

On Wed, Jul 13, 2022 at 8:35 AM Zeng, Oak <oak.zeng@intel.com> wrote:
>
> Thank you sdf for the reply.

please don't top post in mailing list, reply inline instead

>
> It is news to me that samples/bpf tend to go stale. When I looked the samples/bpf folder git history, the last update is from only 2 months ago. And yes I can see samples/bfp is not actively updated recently. We are from Intel's GPU group and we are working on some bpf tools for GPU profiling purpose. We made our work based on the structure of samples/bpf because we can conveniently use libbpf. We chose bpf c frontend (vs python frontend) because python bpf program seems can't execute under non-root leading to some security concerns. This work is not yet upstream but we planned to upstream it.
>
> Now if samples/bpf is going stale, we need to change our plan. Specifically I have a few questions for our future planning:
>
> 1. does bpf community accept more bpf samples such as using bpf to kprobe/tracepoint GPU activities? Is such work helpful/welcome to/by the community? I can see the existing samples and selftest are mainly for general linux profiling such as fs, network etc. Do you accept more samples for specific driver profiling - in our case it is profiling of Intel's i915 GPU driver.
>

Generic BPF tools are generally put into BCC/libbpf-tools ([0]). If
they are very specialized and niche, it might not be accepted. But I'd
try there first.

As for samples/bpf, no we don't add any new things there. It should
either be a selftest-like and go into selftests/bpf, or it should be
outside of the kernel repo.

  [0] https://github.com/iovisor/bcc/tree/master/libbpf-tools

> 2. Should we port our samples/bpf to tools/testing/selftests/bpf for upstream purpose? I am not sure whether tools/testing/selftests/bpf is a good place for our gpu profiling samples. If tools/testing/selftests/bpf is not a good place for gpu profilers, any suggestion where we can upstream our gpu profilers?

If the BPF part of such profilers is complicated and stresses BPF
verifier, we can put those up as "BPF verifier scalability" tests (see
bpf_verif_scale.c in selftests/bpf), it's good to have real-world
complicated examples there to detect regressions. But tool itself
probably should be in libbpf-tools or in some dedicated repo.

>
> Cc other bpf reviewers. Thank you for your considerations!
>
> Thanks,
> Oak
>
> > -----Original Message-----
> > From: sdf@google.com <sdf@google.com>
> > Sent: July 12, 2022 1:23 PM
> > To: Zeng, Oak <oak.zeng@intel.com>
> > Cc: bpf@vger.kernel.org
> > Subject: Re: Build error of samples/bpf
> >
> > On 07/12, Zeng, Oak wrote:
> > > Hello all,
> >
> > > I tried to build the latest samples/bpf following instructions in the
> > > README.rst in samples/bpf folder. I ran into various issue such as:
> >
> > > samples/bpf/Makefile:375: *** Cannot find a vmlinux for VMLINUX_BTF at
> > > any of "  /home/szeng/dii-tools/linux/vmlinux", build the kernel or
> > > set VMLINUX_BTF or VMLINUX_H variable
> >
> > > I was able to fix above issue by enable CONFIG_DEBUG_INFO_BTF in
> > > kernel .config file.
> >
> > > But I eventually ran into other errors.  I had to fix those errors by
> > > install dwarves, updating my clang/llvm to version 10.
> >
> > > I was able to build it if I comment out all the xdp programs from
> > > Makefile. It seems those xdp programs require advanced features such
> > > as data structure layout in vmlinux.h (dumped from vmlinux using
> > > bpftool) and this require special kernel config support.
> >
> > > So I thought instead of fixing those errors one by one, I should ask
> > > those who are working in this area, is there any instructions on how
> > > to build samples/bpf? The README.rst seems out-of-date, for example,
> > > it doesn't mention CONFIG_DEBUG_INFO_BTF. The required llvm/clang
> > > version in README.rst is also out-of-date.
> >
> > > More specifically, to build samples/bpf, is there an example kernel
> > > .config to use? I tried those config here
> > > https://github.com/torvalds/linux/blob/master/tools/testing/selftests/
> > > bpf/config
> > > but build errors persist.
> >
> > > Or is there any other tools I need to install/update on my system?
> >
> > In general, I'd say, samples/bpf tend to go stale. We mostly work on the
> > selftests and don't pay too much attention to the samples :-( Ideally, the
> > samples should be part of selftests so they get exercised by the CI.
> >
> > One thing I can suggest is to look at tools/testing/selftests/bpf/vmtest.sh
> > script. It builds the kernels with vetted configs capable of running selftests.
> > That should be, in theory, be enough to compile the samples.
> >
> > > My whole build log is as below:
> >

[...]

Re: Build error of samples/bpf

[Kumar Kartikeya Dwivedi]

On Tue, 12 Jul 2022 at 16:10, Zeng, Oak <oak.zeng@intel.com> wrote:
>
> Hello all,
>
> I tried to build the latest samples/bpf following instructions in the README.rst in samples/bpf folder. I ran into various issue such as:
>
> samples/bpf/Makefile:375: *** Cannot find a vmlinux for VMLINUX_BTF at any of "  /home/szeng/dii-tools/linux/vmlinux", build the kernel or set VMLINUX_BTF or VMLINUX_H variable
>
> I was able to fix above issue by enable CONFIG_DEBUG_INFO_BTF in kernel .config file.
>
> But I eventually ran into other errors.  I had to fix those errors by install dwarves, updating my clang/llvm to version 10.
>
> I was able to build it if I comment out all the xdp programs from Makefile. It seems those xdp programs require advanced features such as data structure layout in vmlinux.h (dumped from vmlinux using bpftool) and this require special kernel config support.
>
> So I thought instead of fixing those errors one by one, I should ask those who are working in this area, is there any instructions on how to build samples/bpf? The README.rst seems out-of-date, for example, it doesn't mention CONFIG_DEBUG_INFO_BTF. The required llvm/clang version in README.rst is also out-of-date.
>
> More specifically, to build samples/bpf, is there an example kernel .config to use? I tried those config here https://github.com/torvalds/linux/blob/master/tools/testing/selftests/bpf/config but build errors persist.
>
> Or is there any other tools I need to install/update on my system?
>
> My whole build log is as below:
>
> szeng@linux:~/dii-tools/linux$ make M=samples/bpf
> readelf: Error: Missing knowledge of 32-bit reloc types used in DWARF sections of machine number 247
> readelf: Warning: unable to apply unsupported reloc type 10 to section .debug_info
> readelf: Warning: unable to apply unsupported reloc type 1 to section .debug_info
> readelf: Warning: unable to apply unsupported reloc type 10 to section .debug_info make -C /home/szeng/dii-tools/linux/samples/bpf/../../tools/lib/bpf RM='rm -rf' EXTRA_CFLAGS="-Wall -O2 -Wmissing-prototypes -Wstrict-prototypes -I./usr/include -I./tools/testing/selftests/bpf/ -I/home/szeng/dii-tools/linux/samples/bpf/libbpf/include -I./tools/include -I./tools/perf -DHAVE_ATTR_TEST=0" \
>         LDFLAGS= srctree=/home/szeng/dii-tools/linux/samples/bpf/../../ \
>         O= OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/libbpf/ DESTDIR=/home/szeng/dii-tools/linux/samples/bpf/libbpf prefix= \
>         /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a install_headers
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/nlattr.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_errno.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/str_error.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/netlink.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf_prog_linfo.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_probes.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/xsk.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/hashmap.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf_dump.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/ringbuf.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/strset.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/linker.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/gen_loader.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/relo_core.o
>   LD      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf-in.o
>   LINK    /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
>   INSTALL headers
>   CC  samples/bpf/test_lru_dist
>   CC  samples/bpf/sock_example
>   CC  samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.o
>   CC  samples/bpf/../../tools/testing/selftests/bpf/trace_helpers.o
>   CC  samples/bpf/cookie_uid_helper_example.o
>   CC  samples/bpf/cpustat_user.o
>   CC  samples/bpf/fds_example.o
>   CC  samples/bpf/hbm.o
>   CC  samples/bpf/i915_latency_hist_user.o
>   CC  samples/bpf/i915_stat_user.o
>   CC  samples/bpf/ibumad_user.o
>   CC  samples/bpf/lathist_user.o
>   CC  samples/bpf/lwt_len_hist_user.o
>   CC  samples/bpf/map_perf_test_user.o
>   CC  samples/bpf/offwaketime_user.o
>   CC  samples/bpf/sampleip_user.o
>   CC  samples/bpf/sockex1_user.o
>   CC  samples/bpf/sockex2_user.o
>   CC  samples/bpf/sockex3_user.o
>   CC  samples/bpf/spintest_user.o
>   CC  samples/bpf/syscall_tp_user.o
>   CC  samples/bpf/task_fd_query_user.o
>   CC  samples/bpf/tc_l2_redirect_user.o
>   CC  samples/bpf/test_cgrp2_array_pin.o
>   CC  samples/bpf/test_cgrp2_attach.o
>   CC  samples/bpf/test_cgrp2_sock.o
>   CC  samples/bpf/test_cgrp2_sock2.o
>   CC  samples/bpf/test_current_task_under_cgroup_user.o
>   CC  samples/bpf/test_map_in_map_user.o
>   CC  samples/bpf/test_overhead_user.o
>   CC  samples/bpf/test_probe_write_user_user.o
>   CC  samples/bpf/trace_event_user.o
>   CC  samples/bpf/trace_output_user.o
>   CC  samples/bpf/tracex1_user.o
>   CC  samples/bpf/tracex2_user.o
>   CC  samples/bpf/tracex3_user.o
>   CC  samples/bpf/tracex4_user.o
>   CC  samples/bpf/tracex5_user.o
>   CC  samples/bpf/tracex6_user.o
>   CC  samples/bpf/tracex7_user.o
>   CC  samples/bpf/xdp1_user.o
>   CC  samples/bpf/xdp_adjust_tail_user.o
>   CC  samples/bpf/xdp_fwd_user.o
> make -C /home/szeng/dii-tools/linux/samples/bpf/../../tools/bpf/bpftool srctree=/home/szeng/dii-tools/linux/samples/bpf/../../ \
>         OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/bpftool/ \
>         LIBBPF_OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/libbpf/ \
>         LIBBPF_DESTDIR=/home/szeng/dii-tools/linux/samples/bpf/libbpf/
>
> Auto-detecting system features:
> ...                        libbfd: [ OFF ]
> ...        disassembler-four-args: [ OFF ]
> ...                          zlib: [ on  ]
> ...                        libcap: [ OFF ]
> ...               clang-bpf-co-re: [ on  ]
>
>
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/nlattr.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_errno.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/str_error.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/netlink.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf_prog_linfo.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf_probes.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/xsk.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/hashmap.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf_dump.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/ringbuf.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/strset.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/linker.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/gen_loader.o
>   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/relo_core.o
>   LD      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf-in.o
>   LINK    /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
>   CLANG   /home/szeng/dii-tools/linux/samples/bpf/bpftool/profiler.bpf.o
>   GEN     /home/szeng/dii-tools/linux/samples/bpf/bpftool/profiler.skel.h
>   CC      /home/szeng/dii-tools/linux/samples/bpf/bpftool/prog.o
>   CLANG   /home/szeng/dii-tools/linux/samples/bpf/bpftool/pid_iter.bpf.o
>   GEN     /home/szeng/dii-tools/linux/samples/bpf/bpftool/pid_iter.skel.h
>   CC      /home/szeng/dii-tools/linux/samples/bpf/bpftool/pids.o
>   LINK    /home/szeng/dii-tools/linux/samples/bpf/bpftool/bpftool
>   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)?

> 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
>

RE: Build error of samples/bpf

[Zeng, Oak]

Thanks,
Oak

> -----Original Message-----
> From: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> Sent: July 13, 2022 2:21 PM
> To: Zeng, Oak <oak.zeng@intel.com>
> Cc: bpf@vger.kernel.org
> Subject: Re: Build error of samples/bpf
> 
> On Tue, 12 Jul 2022 at 16:10, Zeng, Oak <oak.zeng@intel.com> wrote:
> >
> > Hello all,
> >
> > I tried to build the latest samples/bpf following instructions in the
> README.rst in samples/bpf folder. I ran into various issue such as:
> >
> > samples/bpf/Makefile:375: *** Cannot find a vmlinux for VMLINUX_BTF at
> any of "  /home/szeng/dii-tools/linux/vmlinux", build the kernel or set
> VMLINUX_BTF or VMLINUX_H variable
> >
> > I was able to fix above issue by enable CONFIG_DEBUG_INFO_BTF in
> kernel .config file.
> >
> > But I eventually ran into other errors.  I had to fix those errors by install
> dwarves, updating my clang/llvm to version 10.
> >
> > I was able to build it if I comment out all the xdp programs from Makefile. It
> seems those xdp programs require advanced features such as data structure
> layout in vmlinux.h (dumped from vmlinux using bpftool) and this require
> special kernel config support.
> >
> > So I thought instead of fixing those errors one by one, I should ask those
> who are working in this area, is there any instructions on how to build
> samples/bpf? The README.rst seems out-of-date, for example, it doesn't
> mention CONFIG_DEBUG_INFO_BTF. The required llvm/clang version in
> README.rst is also out-of-date.
> >
> > More specifically, to build samples/bpf, is there an example kernel .config
> to use? I tried those config here
> https://github.com/torvalds/linux/blob/master/tools/testing/selftests/bpf/c
> onfig but build errors persist.
> >
> > Or is there any other tools I need to install/update on my system?
> >
> > My whole build log is as below:
> >
> > szeng@linux:~/dii-tools/linux$ make M=samples/bpf
> > readelf: Error: Missing knowledge of 32-bit reloc types used in DWARF
> sections of machine number 247
> > readelf: Warning: unable to apply unsupported reloc type 10 to
> section .debug_info
> > readelf: Warning: unable to apply unsupported reloc type 1 to
> section .debug_info
> > readelf: Warning: unable to apply unsupported reloc type 10 to
> section .debug_info make -C /home/szeng/dii-
> tools/linux/samples/bpf/../../tools/lib/bpf RM='rm -rf' EXTRA_CFLAGS="-
> Wall -O2 -Wmissing-prototypes -Wstrict-prototypes -I./usr/include -
> I./tools/testing/selftests/bpf/ -I/home/szeng/dii-
> tools/linux/samples/bpf/libbpf/include -I./tools/include -I./tools/perf -
> DHAVE_ATTR_TEST=0" \
> >         LDFLAGS= srctree=/home/szeng/dii-tools/linux/samples/bpf/../../ \
> >         O= OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/libbpf/
> DESTDIR=/home/szeng/dii-tools/linux/samples/bpf/libbpf prefix= \
> >         /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
> install_headers
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf.o
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf.o
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/nlattr.o
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/libbpf_errno.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/str_error.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/netlink.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/bpf_prog_linfo.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/libbpf_probes.o
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/xsk.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/hashmap.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/btf_dump.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/ringbuf.o
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/strset.o
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/linker.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/gen_loader.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/relo_core.o
> >   LD      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf-
> in.o
> >   LINK    /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
> >   INSTALL headers
> >   CC  samples/bpf/test_lru_dist
> >   CC  samples/bpf/sock_example
> >   CC  samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.o
> >   CC  samples/bpf/../../tools/testing/selftests/bpf/trace_helpers.o
> >   CC  samples/bpf/cookie_uid_helper_example.o
> >   CC  samples/bpf/cpustat_user.o
> >   CC  samples/bpf/fds_example.o
> >   CC  samples/bpf/hbm.o
> >   CC  samples/bpf/i915_latency_hist_user.o
> >   CC  samples/bpf/i915_stat_user.o
> >   CC  samples/bpf/ibumad_user.o
> >   CC  samples/bpf/lathist_user.o
> >   CC  samples/bpf/lwt_len_hist_user.o
> >   CC  samples/bpf/map_perf_test_user.o
> >   CC  samples/bpf/offwaketime_user.o
> >   CC  samples/bpf/sampleip_user.o
> >   CC  samples/bpf/sockex1_user.o
> >   CC  samples/bpf/sockex2_user.o
> >   CC  samples/bpf/sockex3_user.o
> >   CC  samples/bpf/spintest_user.o
> >   CC  samples/bpf/syscall_tp_user.o
> >   CC  samples/bpf/task_fd_query_user.o
> >   CC  samples/bpf/tc_l2_redirect_user.o
> >   CC  samples/bpf/test_cgrp2_array_pin.o
> >   CC  samples/bpf/test_cgrp2_attach.o
> >   CC  samples/bpf/test_cgrp2_sock.o
> >   CC  samples/bpf/test_cgrp2_sock2.o
> >   CC  samples/bpf/test_current_task_under_cgroup_user.o
> >   CC  samples/bpf/test_map_in_map_user.o
> >   CC  samples/bpf/test_overhead_user.o
> >   CC  samples/bpf/test_probe_write_user_user.o
> >   CC  samples/bpf/trace_event_user.o
> >   CC  samples/bpf/trace_output_user.o
> >   CC  samples/bpf/tracex1_user.o
> >   CC  samples/bpf/tracex2_user.o
> >   CC  samples/bpf/tracex3_user.o
> >   CC  samples/bpf/tracex4_user.o
> >   CC  samples/bpf/tracex5_user.o
> >   CC  samples/bpf/tracex6_user.o
> >   CC  samples/bpf/tracex7_user.o
> >   CC  samples/bpf/xdp1_user.o
> >   CC  samples/bpf/xdp_adjust_tail_user.o
> >   CC  samples/bpf/xdp_fwd_user.o
> > make -C /home/szeng/dii-tools/linux/samples/bpf/../../tools/bpf/bpftool
> srctree=/home/szeng/dii-tools/linux/samples/bpf/../../ \
> >         OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/bpftool/ \
> >         LIBBPF_OUTPUT=/home/szeng/dii-tools/linux/samples/bpf/libbpf/ \
> >         LIBBPF_DESTDIR=/home/szeng/dii-tools/linux/samples/bpf/libbpf/
> >
> > Auto-detecting system features:
> > ...                        libbfd: [ OFF ]
> > ...        disassembler-four-args: [ OFF ]
> > ...                          zlib: [ on  ]
> > ...                        libcap: [ OFF ]
> > ...               clang-bpf-co-re: [ on  ]
> >
> >
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf.o
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/bpf.o
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/nlattr.o
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/btf.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/libbpf_errno.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/str_error.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/netlink.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/bpf_prog_linfo.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/libbpf_probes.o
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/xsk.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/hashmap.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/btf_dump.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/ringbuf.o
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/strset.o
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/linker.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/gen_loader.o
> >   CC      /home/szeng/dii-
> tools/linux/samples/bpf/libbpf/staticobjs/relo_core.o
> >   LD      /home/szeng/dii-tools/linux/samples/bpf/libbpf/staticobjs/libbpf-
> in.o
> >   LINK    /home/szeng/dii-tools/linux/samples/bpf/libbpf/libbpf.a
> >   CLANG   /home/szeng/dii-tools/linux/samples/bpf/bpftool/profiler.bpf.o
> >   GEN     /home/szeng/dii-tools/linux/samples/bpf/bpftool/profiler.skel.h
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/bpftool/prog.o
> >   CLANG   /home/szeng/dii-tools/linux/samples/bpf/bpftool/pid_iter.bpf.o
> >   GEN     /home/szeng/dii-tools/linux/samples/bpf/bpftool/pid_iter.skel.h
> >   CC      /home/szeng/dii-tools/linux/samples/bpf/bpftool/pids.o
> >   LINK    /home/szeng/dii-tools/linux/samples/bpf/bpftool/bpftool
> >   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
  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
> >

Re: Build error of samples/bpf

[Jiri Olsa]

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
> > >

RE: Build error of samples/bpf

[Zeng, Oak]

Thanks,
Oak

> -----Original Message-----
> From: Jiri Olsa <olsajiri@gmail.com>
> Sent: July 15, 2022 4:26 AM
> To: Zeng, Oak <oak.zeng@intel.com>
> Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>; bpf@vger.kernel.org
> Subject: Re: Build error of samples/bpf
> 
> 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

Hi Jiri,

Thanks for your reply. Yes the problem was a old version of pahole (v 1.21). After installed pahole 1.23 above issue disappeared.

But when I build xdp samples, below error still persist even I updated llvm to version 12 or 14. Anyone had the same issue?

  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.
Error: failed to open BPF object file: Invalid argument
make[1]: *** [samples/bpf/Makefile:439: samples/bpf/xdp_monitor.skel.h] Error 255
make[1]: *** Deleting file 'samples/bpf/xdp_monitor.skel.h'
make: *** [Makefile:1868: samples/bpf] Error 2

> 
> 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
> > > >