The new grub boot system has removed the ability to find out what kernel parameters are acceptable. There is a "help" option, but all it does is scroll rapidly through a text file and revert to the grub screen (I need more than half a second to read several pages of text). If the keyboard were attached during this process I might be able to use CTRL-S and -Q to page through the text.
*** This bug has been marked as a duplicate of bug 215799 ***