The flash.sh script of L4T runs mkbootimg, and outputs /boot/vmlinux.uimg. It looks as if this is not necessary when using u-boot, but the file is always generated.
zImage is used in u-boot…can anyone tell me if vmlinux.uimg is obsolete under u-boot? I tend to wonder if even fastboot uses this, as the -k 6 partition is used under fastboot, and /boot is probably not even considered. Perhaps this is for uefi?