Apparently glibc can be compiled with
--enable-kernel to support older kernel versions. However, I haven't been able to find information on what kernel versions are supported on a particular glibc version. Ideally, I want to see a compatibility matrix for every glibc (2.x) and kernel (2.6.x) releases. Does it exist?
If it doesn't exist, perhaps it's because every glibc versions (in the last 5 years or so) supports all kernels since 2.6.0?
(Arch = x86-64, if that matters)