This is the documentation for the latest (main) development branch of Zephyr. If you are looking for the documentation of previous releases, use the drop-down menu on the left and select the desired version.

Preparing the Boot Device¶

Prepare a USB flash drive to boot the Zephyr application image on a board.

Format the USB flash drive as FAT32.

On Windows, open File Explorer, and right-click on the USB flash drive. Select Format.... Make sure in File System, FAT32 is selected. Click on the Format button and wait for it to finish.

On Linux, graphical utilities such as gparted can be used to format the USB flash drive as FAT32. Alternatively, under terminal, find out the corresponding device node for the USB flash drive (for example, /dev/sdd). Execute the following command:
```
$ mkfs.vfat -F 32 <device-node>
```
Important

Make sure the device node is the actual device node for the USB flash drive. Or else you may erase other storage devices on your system, and will render the system unusable afterwards.
Copy the Zephyr EFI image file zephyr/zephyr.efi to the USB drive.

Booting Zephyr on a board¶

Boot the board to the EFI shell with USB flash drive connected.

Insert the prepared boot device (USB flash drive) into the board.
Connect the board to the host system using the serial cable and configure your host system to watch for serial data. See board’s website for more information.

Note

Use a baud rate of 115200.
Power on the board.
When the following output appears, press F7:
```
Press <DEL> or <ESC> to enter setup.
```
From the menu that appears, select the menu entry that describes that particular EFI shell.
From the EFI shell select Zephyr EFI image to boot.
```
Shell> fs0:zephyr.efi
```
When the boot process completes, you have finished booting the Zephyr application image.