* H. J. Lu: > On Tue, Jul 15, 2025 at 8:47 AM 'Florian Weimer' via X86-64 System V > Application Binary Interface <x86-64-...@googlegroups.com> wrote: >> >> * H. J. Lu: >> >> > Compilers will never know since the build-time glibc is independent of >> > the run-time glibc. If compilers want to be 100% sure that the run-time >> > is GNU2 TLS bug-free, they can require linkers which generate the >> > GLIBC_ABI_GNU2_TLS dependency. >> >> (Such a linker requirement could be enforced by requiring that the >> linker recognizes a command option specific to GLIBC_ABI_GNU2_TLS, and >> that current linkers treat as an error.) >> >> Would such an unconditional requirement be acceptable to GCC 16? I >> don't think so. So we'd still have to design a configure option for it. >> And that requires further compiler changes. It's also not entirely >> clear how this would interact with -fuse-ld. >> >> I just don't think option (b) is trivial from a compiler perspective. >> > > It depends on what we want. If we want 100% guarantee of glibc > run-time GNU2 TLS bug-free, GCC can pass -z gnu2-tls to linker > whenever GNU2 TLS is used with glibc. It is an error if the linker > doesn't support -z gnu2-tls. We can provide a GCC option to disable > -z gnu2-tls.
Unknown -z options are ignored by default: $ ld -z gnu2-tls ld: warning: -z gnu2-tls ignored It would have to be a regular option. But that's just a minor detail. Thanks, Florian
