Linux : 32 bit only what is the trick

Hi, Linux is 32 bit OS and 32 bit only. I ran across this statement today. Although it also says that there are some project going on to port Linux to 16 bit processor, pretty much Linux is 32 bit only.

This puzzles me a bit. Contrary to Windows which only runs on Intel processor, Linux is across so many processors. So theoritically it should be faily straightforward to support a new processor.

I know I am "looking from outside the door", so this thing does not seems a very daunting task. In the kernel there should be a very low layer function which pretty much is in processor dependent buttembly. Although the layer provides some universal function to the upper layer, the kernel for Intel, PowerPC and MISP are in different ISA buttembly.

Then if all these imagination is true, then to port Linux to a 16 bit processor is basically saying to re-write that layer using 16 bit ISA. And if the port is, say, to Intel 8086 from Intel80386, I would imagine it is easier than to port from 80386 to 32 bit PowerPC.

Then what is the real trick?