Set CONFIG_USELIB=n in Ubuntu kernels

[Christian Brauner]

We're currently planning to be more proactive in deprecating the uselib() syscall similar to how we deprecated the sysctl() syscall. This will be a long process of course but the starting point is to set CONFIG_USELIB=n in all new Ubuntu versions. I spoke to Eric and apparently RHEL 8 has it disabled too.

The regression potential is quite minimal as this interface should have very few users and libc hasn't used it since libc4 or libc5.

I was wondering what people's opinion on this were.

The thread is:
https://lore.kernel.org/lkml/20200518130251.zih2s32q2rxhxg6f@wittgenstein
https://lore.kernel<email address hidden>
https://lore.kernel.org/lkml/20200518144627.sv5nesysvtgxwkp7@wittgenstein
https://<email address hidden>

[Seth Forshee (sforshee)]

On the surface this seems like a reasonable thing to do. However I think someone from foundations should weigh in on the topic too.

[Christian Brauner (cbrauner)]

So I've gone through codesearch on Debian and there are no users apart from a bunch of defines for __NR_uselib when it isn't defined.