The instructions in the manual from Purdue discuss only the Galileo Gen 1, but they run the same image on the Gen 2 (as I do also). The Gen 2 has hardware differences in the gpio, pwm, and adc hardware, but as yet Xinu does not support those, so this is not an issue.
Note that the Gen2 uses a different serial cable. It is a 6 pin inline cable using 3.3 voltage levels. In fact the exact same cable as used by the Beaglebone Black and other such boards. A nice change, especially since I have several such cables ready at hand.The best bet for getting Xinu for the Galileo is the real-xinu project on Github. Avoid getting the sources from Purdue that are intended to accompany the book. They are fine for that purpose (having source code identical to what is discussed in the book), but if you actually want to run Xinu, you should get the latest files from Github and build them.
Tom's Computer Info / tom@mmto.org