You're right, but fsl-image-gui-sdk is working since 2hours now and it's not finished, I don't want to wait all this time every time I need to rebuild. I tried HOB which looks really great, but I am trying to select the imx6qsabresd machine, it says it can't find the recipe for udev, if I understood well, I think that's because it's done by meta-openembeded. If you know how to fix this it would be great since HOB should help me a lot.
Anyway, thanks for all your time dedicated to help me !
EDIT : never mind, both work so I will try them !