Hi Daniel, There must be something else funny about your system. I just took a CEI-TK1_SOM, flashed it with Colorado's images from their FTP site (if you don't already have access to these, you should ask Colorado Engineering --- they give it freely to customers), and checked it could boot. I then flashed the current upstream U-Boot, and attempted to boot, with bootm_boot_mode set to `sec' -- and Linux Ubuntu booted. I then set the variable to `nonsec' and see: ... Jetson-TK1 eMMC boot options Enter choice: 1 1: primary kernel Retrieving file: /boot/zImage 5995744 bytes read in 156 ms (36.7 MiB/s) append: console=ttyS0,115200n8 console=tty1 no_console_suspend=1 lp0_vec=2064@0t Retrieving file: /boot/tegra124-tk1-som-pm375-000-c00-00.dtb 59720 bytes read in 11 ms (5.2 MiB/s) ## Flattened Device Tree blob at 82000000 Booting using the fdt blob at 0x82000000 Using Device Tree in place at 82000000, end 82011947 couldn't find /cpus ERROR: arch-specific fdt fixup failed - must RESET the board to recover. ... which is what I expect. My guess is that something on the eMMC has become corrupted, and you may be best off reflashing the entire board using Colorado's image. -- Dr Peter Chubb Tel: +61 2 9490 5852 http://ts.data61.csiro.au/ Trustworthy Systems Group Data61, CSIRO (formerly NICTA)