The ABI status of ELF hash tables

The GP most likely refers to CONFIG_LEGACY_VSYSCALL_NONE enabled in Debian Buster[1] and some other distros (and even WSL kernels on Windows[2]), which is indeed an ABI-breaking change (e.g. gettimeofday() crashes on older glibc, breaking use cases like running containers with older distros).

But it's important to understand that it's not the upstream kernel that broke the ABI (in the default configuration) in this case. On the contrary, they introduced a new mode to improve security while preserving (most of) ABI compatibility[3].

[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=852620
[2] https://github.com/microsoft/WSL/issues/4694
[3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/...