How to create a cross compilation file that uses CC, CXX etc. from the environment?

[criatura2]

Hi, I want to cross compile on a build machine x86_64-linux-gnu to a host aarch64-poky-linux. For that I want to create a meson cross.ini file that should have as content something similar to

[binaries]
c = 'CC' # How to pass this properly?
cpp = 'CXX'
...

[host_machine]
system = 'linux'
cpu_family = 'VAR'

However, I don't know how to actually pass the CC, CXX and other environment variables to cross.ini. Is there a simple way of doing it or do I have to invent something e.g. using sed?

Thanks

[taozuhong]

meson env2mfile output file should give some tips to implement the cross compilation.