I have a xilinx Picozed devkit and am using Petalinux 2016.3
The source dirtectory of u-boot contains an example hello_world.c in build/linux/u-boot/src/u-boot-plnx/examples/standalone
Compilation goes through and even creates an appropriate .o and executable file.
But how is this in u-boot included?
And how can i execute it in u-boot.
The u-boot.map doesn't even show anything relating to example or hello_world.
These examples are not specific or targeted to Xilinx's platforms. This is shipped with open source uboot also.
If you want to run this applications, you may give a try to load it through either tftp or serial loadb commands, and run it, which is explained in the above link.
These applications are not developed by Xilinx.