Here are proper stage 1, and stage 2 uEnv.txt files. From:
debian@beaglebone:~$ cat /etc/dogtag
BeagleBoard.org Debian Image 2016-06-19
debian@beaglebone:~$ cat /uEnv.txt /* stage 1*/
##These are needed to be compliant with Angstrom’s 2013.06.20 u-boot.
loadaddr=0x82000000
fdtaddr=0x88000000
rdaddr=0x88080000
initrd_high=0xffffffff
fdt_high=0xffffffff
##These are needed to be compliant with Debian 2014-05-14 u-boot.
loadximage=echo debug: [/boot/vmlinuz-${uname_r}] … ; load mmc 0:1 ${loadaddr} /boot/vmlinuz-${uname_r}
loadxfdt=echo debug: [/boot/dtbs/${uname_r}/${fdtfile}] … ;load mmc 0:1 ${fdtaddr} /boot/dtbs/${uname_r}/${fdtfile}
loadxrd=echo debug: [/boot/initrd.img-${uname_r}] … ; load mmc 0:1 ${rdaddr} /boot/initrd.img-${uname_r}; setenv rdsize ${filesize}
loaduEnvtxt=load mmc 0:1 ${loadaddr} /boot/uEnv.txt ; env import -t ${loadaddr} ${filesize};
check_dtb=if test -n ${dtb}; then setenv fdtfile ${dtb};fi;
loadall=run loaduEnvtxt; run check_dtb; run loadximage; run loadxrd; run loadxfdt;
mmcargs=setenv bootargs console=tty0 console=${console} ${optargs} ${cape_disable} ${cape_enable} root=/dev/mmcblk0p1 rootfstype=${mmcrootfstype} ${cmdline}
uenvcmd=run loadall; run mmcargs; echo debug: [${bootargs}] … ; echo debug: [bootz ${loadaddr} ${rdaddr}:${rdsize} ${fdtaddr}] … ; bootz ${loadaddr} ${rdaddr}:${rdsize} ${fdtaddr};
debian@beaglebone:~$ cat /boot/uEnv.txt /* stage 2*/
#Docs: http://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0
uname_r=4.1.17-bone-rt-r18
#uuid=
#dtb=
##BeagleBone Black/Green dtb’s for v4.1.x (BeagleBone White just works…)
##BeagleBone Black: HDMI (Audio/Video) disabled:
dtb=am335x-boneblack-emmc-overlay.dtb
##BeagleBone Black: eMMC disabled:
#dtb=am335x-boneblack-hdmi-overlay.dtb
##BeagleBone Black: HDMI Audio/eMMC disabled:
#dtb=am335x-boneblack-nhdmi-overlay.dtb
##BeagleBone Black: HDMI (Audio/Video)/eMMC disabled:
#dtb=am335x-boneblack-overlay.dtb
##BeagleBone Black: wl1835
#dtb=am335x-boneblack-wl1835mod.dtb
##BeagleBone Green: eMMC disabled
#dtb=am335x-bonegreen-overlay.dtb
cmdline=coherent_pool=1M quiet cape_universal=enable ipv6.disable=1
#cmdline=ipv6.disable=1
#In the event of edid real failures, uncomment this next line:
#cmdline=coherent_pool=1M quiet cape_universal=enable video=HDMI-A-1:1024x768@60e
##Example v3.8.x
#cape_disable=capemgr.disable_partno=
#cape_enable=capemgr.enable_partno=
##Example v4.1.x
#cape_disable=bone_capemgr.disable_partno=
cape_enable=bone_capemgr.enable_partno=univ-all
##enable Generic eMMC Flasher:
##make sure, these tools are installed: dosfstools rsync
#cmdline=init=/opt/scripts/tools/eMMC/init-eMMC-flasher-v3.sh