On Thu, 23 Feb 2017, Arnd Bergmann wrote:
I would suggest to not allow building support for 64-bit time_t on a glibc with old kernel headers because of this, but I don't know how hard that is to do in glibc. It is probably safe to
Increasing the minimum kernel headers version globally in glibc is easy (just change LIBC_LINUX_VERSION in sysdeps/unix/sysv/linux/configure.ac). It's also probably less controversial than increasing the minimum runtime version (we require 3.2 or later headers unconditionally, but still allow 2.6.32 kernels at runtime on x86_64 and x86).
Increasing the minimum just for architectures that currently have 32-bit time_t, without changing the runtime minimum, would be trickier.