How to boot a board from a SD card
From RidgeRun Developer Connection
In this section it will be shown how to boot your file system directly from your SD card. For the tutorial it will be used the free SDK for the LeopardBoard DM355 but in the most of SDKs you will find similar options.
1. First you must get a SD Card and format it with a software tool like gParted with the EXT3 system type.
2. Introduce your SD card on your SD card reader and copy all the files allocated in fs/fs/ to it.
3. Start your SDK and go to File system configuration and select the Secure digital card from the File system image target item.
4. Run the make command.
5. Start your board and stop it on the U-Boot prompt. Type printenv and copy the bootargs line.
6. It will be the parameter root= without arguments, fill it with root=/dev/mmcblk0p1 and modify your bootargs line as is shown below
setenv bootargs 'console=ttyS0 [...] root=/dev/mmcblk0p1 rootdelay=2 rootfstype=ext3 [...]'
7. Execute the previous line on your U-Boot prompt and then type saveenv.
8. Run the boot command and wait while your board starts.