How can I upgrade my current L4T 21.2 to L4T 21.3 without doing a complete reinstall.
Unfortunately there are no instructions for doing that. You would need to update at least the U-Boot, kernel, DTB and user-space binaries. The last three are easy but I’m not sure about the U-Boot. And I’m not sure either, if I’m missing a component here.
I updated from L4T 21.2 to 21.3 with following commands.
They don’t update U-Boot, but I can boot Ubuntu.
wget http://developer.download.nvidia.com/embedded/L4T/r21_Release_v3.0/Tegra124_Linux_R21.3.0_armhf.tbz2 sudo tar -vxjf Tegra124_Linux_R21.3.0_armhf.tbz2 cd Linux_for_Tegra sudo ./apply_binaries.sh -r / cp /boot/extlinux/jetson-tk1_extlinux.conf.[your boot device] /boot/extlinux/extlinux.conf
Check driver files
sha1sum -c /etc/nv_tegra_release
Reset Jetson TK1
Login to Jetson TK and check kernel version
Then, I installed “The Grinch” Custom Kernel 21.3.
It seems when jetson tk1 boots, U-Boot reads /boot/extlinux/extlinux.conf from the boot storage and load a kernel with parameters specified in that file.
So, I think you don’t need to update U-Boot unless your current U-Boot cannot read extlinux.conf from your storage or you want new futures in new U-Boot.