But after setting up the sdcard, the board don't want to start.
I didn't have output on serial output with the u-boot.imx from the fedora minimal archive.
After build u-boot from the head of u-boot-imx repository (and apply this patch :
https://www.mail-archive.com/u-boot@lists.denx.de/msg167764.html), I was able to boot a fedora 21 minimal system.