Yocto Setup TFTP/NFS¶

Running Yocto rootfs on Variscite board using TFTP & NFS¶

On the Host¶

Prepare the rootfs folder:

cd ~/var-ti-yocto

sudo mkdir rootfs

cd rootfs

sudo tar --zstd -xvf ../build/deploy-ti/images/am62x-var-som/var-default-image-am62x-var-som.rootfs.tar.zst

Make sure the NFS server is installed:

sudo apt install nfs-kernel-server

Edit /etc/exports. E.g.

sudo nano /etc/exports

And add the following line to it (replace with the actual username):

/rootfs    *(rw,sync,no_root_squash,no_all_squash,no_subtree_check)

Restart the NFS server:

sudo /etc/init.d/nfs-kernel-server restart

Make sure the TFTP server is installed:

Ubuntu 24.04 and newer:

sudo apt install xinetd tftpd-hpa tftp-hpa

Ubuntu 22.04 and older:

sudo apt install xinetd tftpd tftp

Configure tftpd-hpa for Ubuntu 24.04 and newer:

sudo nano /etc/default/tftpd-hpa

TFTP_USERNAME="tftp"
TFTP_DIRECTORY="/tftpboot"
TFTP_ADDRESS=":69"
TFTP_OPTIONS="--secure"

Configure tftpd for Ubuntu 22.04 and older:

ls /usr/sbin/in.tftpd

sudo nano /etc/xinetd.d/tftp

service tftp
{
    protocol = udp
    port = 69
    socket_type = dgram
    wait = yes
    user = nobody
    server = /usr/sbin/in.tftpd
    server_args = /tftpboot
    disable = no
}

And run:

sudo mkdir /tftpboot

sudo chmod -R 777 /tftpboot

sudo systemctl restart xinetd

sudo systemctl restart tftpd-hpa

cd ~/var-ti-yocto/build/

sudo cp deploy-ti/images/am62x-var-som/Image /tftpboot

for f in deploy-ti/images/am62x-var-som/*.dtb; do if [[ -L $f ]] && [[ $f != *am62x-var-som.dtb ]]; then sudo cp $f /tftpboot; fi done

sudo rename 's/Image-//' /tftpboot/Image-*.dtb

Make adjustments to the rootfs:

When using NetworkManager on the target, configure NetworkManager not to manage the interface used for the NFS boot by adding the following to /rootfs/etc/NetworkManager/NetworkManager.conf:

[keyfile]
unmanaged-devices=interface-name:eth0

Enable DNS:

sudo ln -fs /proc/net/pnp /rootfs/etc/resolv.conf

On the Target¶

Update the U-Boot enviroment by adding the following lines to the uEnv.txt file on the SD card/eMMC boot partition:

svrip=<HOST_IP_ADDRESS>  (replace <HOST_IP_ADDRESS> with the actual IP address of your host - run 'ifconfig' on the host to get it)
ipaddr=<TARGET_IP_ADDRESS> (replace <TARGET_IP_ADDRESS> with the IP address for the target)
image=Image

rootpath=/home/<uname>/var-fslc-yocto/rootfs
fdtfile=k3-am62x-var-som-symphony.dtb

netargs=setenv bootargs console=${console} ${optargs} root=/dev/nfs nfsroot=${serverip}:${rootpath},nolock,v3 rw ip=${ipaddr}:::::eth0

netboot=tftp ${loadaddr} ${image}; tftp ${fdtaddr} ${fdtfile}; run netargs; booti ${loadaddr} - ${fdtaddr}

uenvcmd=setenv serverip ${svrip}; setenv ipaddr ${ipaddr}; run netboot

You are all set. Connect the target board to the same network as the host using an Ethernet cable, power cycle it and it should boot over NFS.