# How to explain rehosting and retargeting with T-diagrams?

I'm currently learning for an exam about compilers and found the following question:

(3 p.) Bootstrapping: Explain the concepts of rehosting and retargeting. Use T-diagrams.

As far as I understand, rehosting means to compile a compiler for another platform (host), so it should look like this:

-------------
| a       b |     --------------
-----   -----     | a        b |
| c |-------------    ------
-----| c       x || x |
-----   ----------
| ? |
-----


Is this correct? And what does retargeting mean?

-
? should be replaced by x, see these lecture notes.