Bureaucrats, dave_user, Administrators
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After system power-up, U-Boot prints some information about itself and about the system it is running on. Once the bootstrap sequence is completed, the prompt is printed and U-Boot is ready to accept user's commands. U-Boot manages an environment space where several variables can be stored. These variables are extremely useful to permanently save system settings (such as ethernet MAC address) and to automate boot procedures. This environment is redundantly stored in two physical sectors of boot flash memory; the default variables set is hard-coded in the source code itself. User can modify these variables and add new ones in order to create his/her own custom set of configurations. The commands used to do that are <code>setenv</code> and <code>saveenv</code>. This process allows the user to easily set up the required configuration. Once U-Boot prompt is available, it is possible to print the whole environment by issuing the command <code>printenv</code>.
For further information on the use of U-Boot, please refer to http://www.denx.de/wiki/view/DULG/UBoot.
===Kernel===
Linux kernel for Zynq processors is maintained primarily by Xilinx, that constantly works in close cooperation with Linux community in order to push all the released drivers into mainstream kernel.
Kernels released within BELK derive directly from Xilinx Zynq kernels, with patches added by DAVE Embedded Systems to support the BORA and BORAX hardware platforms.
===Target root file system===
The Linux kernel running on the target needs to mount a root file system. Building a root file system from scratch is definitively a complex task because several well known directories must be created and populated with a lot of files that must follow some standard rules. Again we will use pre-packaged root file systems that make this task much easier. <u>Please note that using a pre-packaged root file system can lead to conflicts with the application binaries obtained using the pre-built cross-toolchain: as a general rule, dynamically linking an application against libraries built with a different toolchain can cause malfunctioning.</u>
