So we produced a build with buildroot which includes rootfs.tar, rootfs.ext2 , u-boot, uImage and zImage. According to pdf you added we didn't change any files in profiles>linux>firmware but changed the files in profiles>linux>files with rootfs.tar.bz2, u-boot-imx6qsabreauto_sd.imx, uImage, zImage-imx6q-sabreauto.dtb (by putting same names.)
We started mfg tool again(from mfgtool2-yocto-mx-sabreauto-sdcard-sd3). It worked to some degree then gave error on pushing mksdcard.sh .
What shoud we do now?
Update : We managed to send our rootfs to board with this way. But we aren't sure that board got our kernel since every qt demo comes with installation in it gives segmentation fault. So how we can test it?