Hello!
I try to your Gentoo image. But, not working my Galileo. My Galileo firmware is newest version.
Please look following URL gist. This is Galileo Serial Console boot-log. last result is "Error 17 Cannot mount selected partition"
I have experience same error, this situation is "Newest Galileo Yoct kernel + Debian" "Previous Galileo Yoct Kernel + Debian" is good.
if you can open the "image-full-clamton.ext3" gentoo image, can I Download?
I try to previous Kernel image on test the Galileo.
Regards,