I have to run a XFP module under Linux with a JDSU XFP Evaluation kit (http://www.jdsu.com/product-literature/xfptxevalkit_tn_cms_ae.pdf). The problem is to communicate with PC via USBXpress protocol under Linux system (Ubuntu). After some research, I see that's not so simple to make it work under Linux.
As I'm quite a beginner in USB development, I required your help.

I found some solutions for my problem, but I don't know which one is the best and require less time (it's a very important part of my project and it has to be resolved rapidly).

1. to find a version of USBXpress driver for Linux : it seems that it doesn't exist yet
2. to develop my own driver for Linux (by modifying libusb ?)
3. last resort : communicate via RS232 by adding a component between the JDSU card and the computer which converts RS232 to USBXpress.