However, when building a uefi crate, the RUSTFLAGS don't work.
$ cargo build -Z build-std=core --target=x86_64-unknown-uefi
error: cannot produce proc-macro for `uefi-macros v0.2.1` as the target `x86_64-unknown-linux-musl` does not support these crate types
Programs on musl target normally statically link to musl libc, but can dynamically link using
see: https://github.com/rust-lang/rust/issues/59302
However, when building a uefi crate, the RUSTFLAGS don't work.