What is the difference between vdso32 amd vdsox32?

Question

I apologize if the answer to this question is apparent, but why are there two versions^[1] of the vdso for 32-bit executables on linux systems, and what is the criteria used to select among them?

_{* as can be found in /lib/modules/KERNEL_NAME/vdso}

Answer 1

x32 is a Linux ABI which is kind of a mix between x86 and x64. It uses 32-bit address size but runs in full 64-bit mode, including all 64-bit instructions and registers available.