I try to build a program for x32 model (that is, using gcc with -mx32 flag). A simple "hello" x32 program builds and works fine. But my program uses libreadline.so (and other libs), and I cannot find them for x32 model.

For the older i386 model (using gcc -m32 ...), I install the i386 version of libreadline by command

apt install libreadline-dev:i386

How do I install the x32 version of libreadline?