As my understanding, I can compile my C code into 32bit binary or 64bit easily, but, some open source projects sais "We don't support 32bit CPU", so why? what makes the code source 64bit only?

I already checked many topics, questions & responses, but all are related to the OS, CPU, and the compiled binary files. While my question is related to the code source itself.

CodePudding user response：

The instruction sets of CPUs will vary, and the instructions available will vary depending on the mode it's running in. The program might rely on larger integers provided in 64-bit mode, or it might have assembler that uses 64-bit instructions.

The different modes of operation also have different memory models. For example, a 32-bit Windows program can address 4 GiB of memory (a huge chunk of which it can't even use). On the other hand, a 64-bit Windows program can access virtually unlimited memory.