uboot for overlay in

U-Boot supports overlay functionality, which allows dynamically loading and applying device tree overlays at runtime. Device tree overlays are used to modify the device tree without modifying the base device tree file. This feature is useful for adding or removing devices, enabling or disabling certain features, or making configuration changes without modifying the original device tree file.

To use overlays in U-Boot, you need to enable the CONFIG_OF_OVERLAY option in your U-Boot configuration. Once enabled, you can load and apply overlays using the "fdt" command in U-Boot's command-line interface.

Here's an example of how to load and apply an overlay in U-Boot:

1. Load the base device tree:

   fatload mmc 0:1 ${fdt_addr_r} base.dtb

2. Load the overlay:

   fatload mmc 0:1 ${fdt_overlay_addr_r} overlay.dtbo

3. Apply the overlay to the base device tree:

   fdt apply ${fdt_overlay_addr_r}

4. Boot the kernel with the modified device tree:

   bootm ${kernel_addr_r} - ${fdt_addr_r}

Make sure to replace "mmc 0:1" with the appropriate storage device and partition where your device tree files are located.

Note that the exact commands and syntax may vary depending on your U-Boot version and configuration. Please refer to the U-Boot documentation or consult your board's manufacturer for more specific instructions on using overlays with U-Boot.