TFTP is commonly used to load bootloader, kernel, and rootfs images to embedded targets (ARM boards, routers, IoT devices) during development or recovery. It's simple (no auth/encryption), fast on local networks, and supported by most bootloaders like U-Boot. Step 1 - Set Up a TFTP Server on the Host Edit /etc/default/tftpd-hpa : Create the directory and restart: Step 2 - Copy Images into /tftpboot bootloader ( u-boot.img ) kernel ( zImage or uImage ) device tree blob ( devicetree.dtb ) rootfs ( rootfs.ext4 or rootfs.tar.gz ) Step 3 - Configure Networking on the Board's U-Boot CLI On the embedded board's U-Boot CLI (via serial), configure networking: Step 4 - Load Images over TFTP into RAM Replace addresses based on your board's memory map: Step 5 - Boot from RAM Optional - Flash to NAND/eMMC Permanently After verifying a successful RAM boot, flash to NAND/eMMC permanently: Troubleshooting TFTP timeout - check firewall/network cable, verify tftpd-hpa is running.

Architecture and Core Concepts

File not found - confirm the file exists in /tftpboot with correct permissions. 'bad magic number' on bootz - wrong file type; use uImage or the bootz command matching zImage . Boots but hangs - verify the dtb matches and kernel/initrd addresses are correct.

Execution Syntax and Code Implementation

Terminalbash
sed to load bootloader, kernel, and rootfs images to embedded targets (ARM boards, routers, IoT devices) during development or recovery
Terminalbash
sed on your board's memory map: Step 5 - Boot from RAM Optional - Flash to NAND/eMMC Permanently After verifying a successful RAM boot, flash to NAND/eMMC permanently: Troubleshooting TFTP timeout - check firewall/network cable, verify tftpd-hpa is running

Gotchas and Troubleshooting Checklist

  • Permission & Access Control - verify user privilege level (sudo access or file ownership) before running commands.

  • Environment & Path Resolution - confirm environment variables and binary PATH entries match target software releases.

  • Log Diagnostics - inspect relevant system logs or application trace outputs to verify clean execution.

Following these steps provides a clean, reliable, and production-ready solution for load kernel, bootloader & filesystem images via tftp on embedded targets.