U-Boot

 

• Stop the beagleboard from booting by pressing any key

• printenv

1. print all the environment variables

• print bootcmd

1. print the individual command value

• setenv → change any variable

1. setenv ipaddr 192.168.1.11

2. when we print the ipaddr using printenv, it displays

1. printenv ipaddr

• 192.168.1.11

3. To remove the value to ipaddr, use the above but without argument

1. setenv ipaddr

• saveenv

1. update the variable that are changed to flash.

• boot

1. runs the default boot command

• help or ?

1. Displays the available command

• To erase the variables saved in nand

1. Nand erase 26000 2000

• tftp

1. Loads a file from the network to ram

• bootargs

1. It is the parameter passed to the Kernel during booting. Important parameter is the location of the rootfilesystem.

2. For finding the rootfs in the SD card 2nd partition it is given as 

1. root=/dev/mmcblk0p2

3. If the rootfs is to be nfs mounted then

1. root=/dev/nfs

4. Which console you are going to use

1. console=ttyO0,115200n8

• bootdelay

1. Time delay for booting the Kernel

• bootm ${addr}

1. Address from which we can boot the uImage.

• bootz ${addr}

1. Address from which we can boot the zImage.

• imi {addr}

1. Gives the information at location 80000000

• reset → Reboot the cpu.