following this guide
https://doc.rust-lang.org/rustc/targets/custom.html
rustc +nightly -Z unstable-options --target=x86_64-unknown-linux-gnu --print target-spec-json
https://doc.rust-lang.org/rustc/targets/custom.html
rustc +nightly -Z unstable-options --target=x86_64-unknown-linux-gnu --print target-spec-json