Yes it is possible.
If there is network then you can always use tftpboot.
If no network you can use UART to load the changed boot loader binaries to RAM.
For example:
Boot to u-boot prompt. Then on U-boot prompt enter command loady. You will see something like below:
Then transfer your new binaries using the YMODEM interface in Teraterm:
You should pick your binary and send:
It will take some time and it completes.
## Ready for binary (ymodem) download to 0x82000000 at 115200 bps...
CCxyzModem - CRC mode, 1(SOH)/1029(STX)/0(CAN) packets, 5 retries
## Total Size = 0x00101378 = 1053560 Bytes
The Binary would be loaded to ${loadaddr}.
You can just verify by doing:
md ${loadaddr}
Now we have the new u-boot.img in RAM at location ${loadaddr} need to write a file to FAT i.e the boot partition of SD card using:
fatwrite mmc 1 ${loadaddr} u-boot.img 101378
Note; The size should always be given in Hex. U-boot takes size in hex so i am using 101378 in hex instead of 1053560 in decimal.
Similar approach can be used to update any binary on the SD card.
Best Regards,
Keerthy
