pahole starts to use libbpf definitions and APIs since v1.13 after the
commit 21507cd3e97b ("pahole: add libbpf as submodule under lib/bpf").
It works well with the git repository because the libbpf submodule will
use "git submodule update --init --recursive" to update.

Unfortunately, the default github release source code does not contain
libbpf submodule source code and this will cause build issues, the tarball
from https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ is same with
github, you can get the source tarball with corresponding libbpf submodule
codes from

https://fedorapeople.org/~acme/dwarves

This change documents the above issues to give more information so that
we can get the tarball from the right place, early discussion is here:

https://lore.kernel.org/bpf/2de4aad5-fa9e-1c39-3c92-9bb9229d0966@loongson.cn/ (local)

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
  Documentation/bpf/bpf_devel_QA.rst | 13 +++++++++++++
  1 file changed, 13 insertions(+)

diff --git a/Documentation/bpf/bpf_devel_QA.rst b/Documentation/bpf/bpf_devel_QA.rst
index d05e67e..253496a 100644
--- a/Documentation/bpf/bpf_devel_QA.rst
+++ b/Documentation/bpf/bpf_devel_QA.rst

@@ -449,6 +449,19 @@ from source at
  
  https://github.com/acmel/dwarves
  
+pahole starts to use libbpf definitions and APIs since v1.13 after the
+commit 21507cd3e97b ("pahole: add libbpf as submodule under lib/bpf").
+It works well with the git repository because the libbpf submodule will
+use "git submodule update --init --recursive" to update.
+
+Unfortunately, the default github release source code does not contain
+libbpf submodule source code and this will cause build issues, the tarball
+from https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ is same with
+github, you can get the source tarball with corresponding libbpf submodule
+codes from
+
+https://fedorapeople.org/~acme/dwarves
+