In our multi-process prototype, we are using a recompiled libc in preload mode to ensure that we are handling all syscalls correctly. Ultimately, I don't think we want to require recompiling libc of users. Instead, I think we want to get all tests working without preloading the recompiled libc.

https://github.com/shadow/shadow/blob/dev/docs/using-recompiled-libc.md