strace reports x32 and 64 bit mode

Question

I am confused about this strace report on an ArchLinux, 64bit intel machine:

~ sudo strace -c -p 876
[sudo] password for pmatos: 
strace: Process 876 attached
strace: [ Process PID=876 runs in x32 mode. ]
strace: [ Process PID=876 runs in 64 bit mode. ]

Why does it say that the process runs in both x32 and 64bit mode? I assume x32 means 32 bit mode.

Answer 1

strace have a handful of heuristics to try to detect the mode of the binary (32bit, 64 bit, x32 and so on).

This logic is not accurate in all cases, so you're seeing a result of that. (This is also the consensus on the linux kernel mailing list)