They're using a fork of musl for compatibility that omits some things: https://fuchsia.dev/fuchsia-src/concepts/system/libc https://fuchsia.dev/fuchsia-src/conc

They're using a fork of musl for compatibility that omits some things: https://fuchsia.dev/fuchsia-src/concepts/system/libc https://fuchsia.dev/fuchsia-src/concepts/system/libc >Fuchsia does not require that programs use libc's ABI. Programs are free to use their own libc, or to do without. As has been said in other comments, it's not much different from Wine or Linux emulation in FreeBSD.