.. _ConfiguringTheBootloader-7: Configuring the Bootloader ========================== The Device Tree ---------------------- * Use the following command to list the available file's within the boot media's Boot partition (this is typically where binaries used for boot are stored): .. code-block:: none :caption: Target (U-Boot) ls mmc 0:1 .. code-block:: none :caption: Example Output => ls mmc 0:1 44 bootenv.txt 52270 imx7d-phyboard-zeta-1110110c.dtb 52286 imx7d-phyboard-zeta-2111101e.dtb 52262 imx7d-phyboard-zeta-2111111e.dtb 52286 imx7d-phyboard-zeta-2211101e.dtb 52262 imx7d-phyboard-zeta-2211111e.dtb 52238 imx7d-phyboard-zeta-kit.dtb 2126 imx7d-phyboard-zeta-m4.dtbo 240 imx7d-phyboard-zeta-peb-av-02-rev0.dtbo 4652 imx7d-phyboard-zeta-peb-av-02.dtbo 3577 imx7d-phyboard-zeta-peb-av-06.dtbo 3256 imx7d-phyboard-zeta-peb-d-rpi.dtbo 42848 imx7s-phyboard-zeta-kit.dtb 52238 oftree 9715904 zImage System Volume Information/ 15 file(s), 1 dir(s) Working with Overlays --------------------- The PHYTEC BSP also comes with some device tree overlays to help evaluate certain interfaces and accessory hardware. The table :ref:`Linux Device Tree Summary ` in the Release Notes shows an overview of all available overlays. Enable an Overlay ~~~~~~~~~~~~~~~~~ * U-boot has an extra environment variable called "overlays" to apply device tree overlay files. We can enable device tree overlays with it like so: .. code-block:: none :caption: Target (U-boot) setenv overlays imx7d-phyboard-zeta-peb-d-rpi.dtbo saveenv boot * Moreover, it's possible to enable multiple overlays by separating them with a space. .. code-block:: none :caption: Target (U-boot) setenv overlays imx7d-phyboard-zeta-peb-d-rpi.dtbo imx7d-phyboard-zeta-m4.dtbo saveenv boot The ``saveenv`` command stores the boot environment to non-volatile memory. If you would like temporarily adjust the boot environment, you can omit the ``saveenv`` command and the boot environment will go back to the previously saved settings on the next boot. Reset the U-Boot Environment to Default Settings ------------------------------------------------ * In order to revert the U-Boot environment back to its original settings, run the following: .. code-block:: none :caption: Target (U-Boot) env default -f -a saveenv boot