test_maps in ubuntu_bpf failed to build on B-hwe-edge 5.3 (BTF is required, but is missing or corrupted.)

[Po-Hsu Lin]

Issue found on 5.3 Bionic hwe:
 Running './test_maps'
 libbpf: BTF is required, but is missing or corrupted.
 Failed to load SK_SKB verdict prog

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1845860

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Po-Hsu Lin (cypressyew)]

It looks like we need clang-9 for this, quoted from upstream discussion:
  You need at least clang-9.0.0 (not yet released) to run some of these
  tests successfully, as they rely on Clang's support for
  BTF_KIND_VAR/BTF_KIND_DATASEC.

https://lore.kernel<email address hidden>/T/

[Paolo Pisati (p-pisati)]

FWIW, i'm having a similar problem on Focal 5.4:

https://paste.ubuntu.com/p/CdFBr9QmHp/

...
libbpf: Error loading .BTF into kernel: -22.
Failed to load SK_SKB verdict prog

but i have clang-10:

ii clang 1:10.0-50~exp1 amd64 C, C++ and Objective-C compiler (LLVM based)
ii clang-10 1:10.0.0-2ubuntu2 amd64 C, C++ and Objective-C compiler
ii libclang-common-10-dev 1:10.0.0-2ubuntu2 amd64 Clang library - Common development package
ii libclang-cpp10 1:10.0.0-2ubuntu2 amd64 C++ interface to the Clang library
ii libclang1-10 1:10.0.0-2ubuntu2 amd64 C interface to the Clang library

[Po-Hsu Lin (cypressyew)]

Test passed with Bionic 5.3 Oracle

[Po-Hsu Lin (cypressyew)]

Test passed with 5.4.0-42.46~18.04.1
(not failing with this issue anymore, but with some other issues)