fatal: unable to access 'https://github.com/libbpf/libbpf.git/': Could not resolve host: github.com

[donghaiqiao]

The bcc source being pulled in by the yocto meta-observation layer is version of v0.20.0. When I built bcc with yocto, the build process hit an error "fatal error: libbpf/src/bpf.h: No such file or directory". Having debugged this problem further, I found out the problem was that the submodule src/cc/libbpf was not populated into the source tree. After I added a "COMMAND_ECHO STDOUT" to the end of the following command in the root CMakeLists.txt
execute_process(COMMAND git submodule update --init --recursive
WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} COMMAND_ECHO STDOUT)

then built again, this command printed an error:
fatal: unable to access 'https://github.com/libbpf/libbpf.git/': Could not resolve host: github.com

Now, if I manually do "git clone https://github.com/libbpf/libbpf.git" in the directory src/cc/libbpf, the libbpf repo can be successfully pulled in. So I don't think that there are any yocto and networking configurations problem on my build machine because the source of bcc can be successfully pulled in through its bcc_git.bb recipe. I suspect that problem was caused by the bcc make file. I wonder whether anyones in the community have ever encountered this problem ? Thanks in advance!