搞定

用file看一下a.out里写的loader是/lib/ld-musl-x86_64.so.1，建立符号链接，指向musl目录下的libc.so即可。

appy@ubuntu:~$ file ./a.out
./a.out: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib/ld-musl-x86_64.so.1, not stripped
happy@ubuntu:~$ ls -la /lib/ld-musl-x86_64.so.1
lrwxrwxrwx 1 root root 52 Jan  6 18:43 /lib/ld-musl-x86_64.so.1 -> /opt/cross/x86_64-linux-musl/lib/ld-musl-x86_64.so.1
happy@ubuntu:~$ ls -la /opt/cross/x86_64-linux-musl/lib/ld-musl-x86_64.so.1
lrwxrwxrwx 1 root root 7 Jan  6 18:49 /opt/cross/x86_64-linux-musl/lib/ld-musl-x86_64.so.1 -> libc.so
happy@ubuntu:~$ ./a.out
hello world.
--
FROM 222.130.137.*