Is there any guidance on how to make and load a bare metal or FreeRTOS system onto a Jetson TK1? Failing that, where can I get the source and build instructions for uboot for the TK1?
Have you checked the Jetson TK1 wiki - http://elinux.org/Jetson_TK1 to find the information you want?
u-boot and the source code can be found here :
As far as implementing bare metal or porting FreeRTOS goes, getting the system to ‘boot’ should be fairly easy (look at the asm code from u-boot and then the base port for any A15 core from FreeRTOS, if there is not an A15 core try any A core)
However, getting the rest of the Tegra-K1 to work eg the HDMI, SATA, etc interfaces will take a long time.
I do not think anyone has done a port for the Tegra-K1, Nvidia have not. FreeRTOS is meant for a small embedded system, the Tegra K1 is a ‘large’ (desktop) type system.
The Linux code is very different from the way RTOS is done, there is an extra abstraction layer in Linux. RTOS drivers work directly with the peripheral registers, Linux uses an abstraction layer to cope with multiple platforms.