make: *** [.output/minimal.skel.h] Error 139 about libbpf-bootstrap HOT 9 CLOSED

Try using a newer version of LLVM.

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make sure you are compiling BPF source code with -g compiler flag, which will make Clang generate BTF information.

But crash shouldn't happen anyway, so can you share object file you are using to generate skeleton?

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@RuchiSaluja8 #92 should help with bpftool building issues

as for no .o, make clean and try again (but with older Clang to reproduce it)

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@RuchiSaluja8 actually, I think your original crash issue will be solved by #93, bpftool had issue with .bpf.o files that don't have BTF and it was fixed, but libbpf-bootstrap didn't have that fix in its bpftool submodule yet. I've updated bpftool to latest.

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It is necessary to generate skeletons with bpftool. The steps you provide work for me. Could you run bpftool manually to see what will happen? It is even better to get a stack trace with gdb.

By the way, you will see the command of GEN_SKEL with make V=1 minimal.

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I am not sure if this is what you meant by running bpftool manually.. I am fairly new to libbpf and bpftool. Based on my understanding till now, I tried running this bpftool command : bpftool --debug prog load /home/imgadmin/libbpf-bootstrap/examples/c/.output/minimal.bpf.o /home/imgadmin/Desktop/libbpf-test-dir/minimal.skel.h and got an error:

root@l156311423:~# bpftool --debug prog load /home/imgadmin/libbpf-bootstrap/examples/c/.output/minimal.bpf.o /home/imgadmin/Desktop/libbpf-test-dir/minimal.skel.h
libbpf: loading /home/imgadmin/libbpf-bootstrap/examples/c/.output/minimal.bpf.o
libbpf: section(1) .text, size 0, link 0, flags 6, type=1
libbpf: skip section(1) .text
libbpf: section(2) tp/syscalls/sys_enter_write, size 104, link 0, flags 6, type=1
libbpf: found program tp/syscalls/sys_enter_write
libbpf: section(3) license, size 13, link 0, flags 3, type=1
libbpf: license of /home/imgadmin/libbpf-bootstrap/examples/c/.output/minimal.bpf.o is Dual BSD/GPL
libbpf: section(4) .bss, size 4, link 0, flags 3, type=8
libbpf: section(5) .rodata, size 28, link 0, flags 2, type=1
libbpf: section(6) .symtab, size 192, link 8, flags 0, type=2
libbpf: section(7) .reltp/syscalls/sys_enter_write, size 32, link 6, flags 0, type=9
libbpf: section(8) .strtab, size 126, link 0, flags 0, type=3
libbpf: skip section(8) .strtab
libbpf: Corrupted ELF file: index of strtab invalid
Error: failed to open object file

Seems like there is an issue with the object file itself.

Can you tell me if I should try some other bpftool command manually?

Also, I could see the command of GEN_SKEL even without specifying V=1.

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Thanks for the suggestion @chenhengqi. I have installed the latest version of LLVM (after following the steps given here and adding the build directory's path to environment).
But I still see the same error when running make command.

PS I also have other versions of LLVM and clang installed for other software. Will removing those versions solve this issue?

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Also, I could see the command of GEN_SKEL even without specifying V=1.
If you run make V=1 minimal, you should see that GEN_SKEL is expanded to XXXXX /bpftool gen skeleton .output/minimal.bpf.o > .output/minimal.skel.h.
The issue here is that bpftool fails to generate the skeleton. libbpf-bootstrap builds its bpftool instead of using the system one.
It may help if you generate the skeleton manually with the bpftool that is built by libbpf-bootstrap. It would be even better to have a stactrace.

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Thanks for the suggestion @chenhengqi. I have installed the latest version of LLVM (after following the steps given here and adding the build directory's path to environment). But I still see the same error when running make command.

PS I also have other versions of LLVM and clang installed for other software. Will removing those versions solve this issue?

After updating LLVM and CLang, I cloned this repository again and got different errors on running make minimal:
https://gist.github.com/RuchiSaluja8/739b91f05169b0bc1ff108e514da3f25

@ThinkerYzu1 There is no gen skeleton output for minimal this time, only for profiler. The output for make V=1 minimal is also in the gist link mentioned above.
@anakryiko BPF code compilation is done with -g flag. There was no .o file generated for minimal this time.

However, running CLANG=Nope make -j8 minimal worked to resolve the errors I was getting.

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