This article provides a step-by-step guide on upgrading U-Boot from shell mode on Juniper SRX branch devices.

You can perform a U-Boot upgrade via the root user from the shell mode using the following command:

bootupgrade -u /boot/uboot -l /boot/loader

For example, in the scenario below, the device is running Junos OS 15.1X49-D210, with U-Boot version 3.6 as the available version and 3.9 as the current version.

root@srx> show system firmware

Part                       Type      Tag  Current   Available Status

                                                  version   version

Routing Engine 0 RE BIOS    0   3.9         3.6           OK

This indicates that the device was previously running a newer Junos OS version (e.g., 19.3), which installed U-Boot 3.9 and preserved it even after the downgrade to 15.1.

The bootupgrade command upgrades the U-Boot version that is bundled with the current Junos OS version. In this case, running the command would downgrade U-Boot from 3.9 to 3.6, since 3.6 is the available version.

The goal is to upgrade U-Boot to version 3.10. To achieve this, follow these steps:

• Obtain U-Boot 3.10 Files: Identify another SRX device running U-Boot 3.10.
• Verify U-Boot and Loader Files on Source Device:

root@srx> show system firmware

Part                      Type      Tag   Current  Available Status

                                                  version   version

Routing Engine 0 RE BIOS    0   3.10        3.12        OK

root@srx% ls

bios-autoupgrade.conf  loader.rc        uboot_siege

defaults        modules         ushell

loader <<<<<<<     support.4th       ushell_jsrxnle

loader.4th       uboot <<<<<<<      ushell_siege

loader.conf       uboot_jsrxnle

• Copy Files to the Target Device (DUT): Transfer the loader and uboot files to /boot/ directory on the target device.
• Run the U-Boot Upgrade Command:

root@srx> start shell

root@srx% bootupgrade -u /boot/uboot -l /boot/loader

Upgrading Loader...

#####################################

Verifying the loader image... OK

Upgrading U-Boot...

###############################################################################################################

Verifying the new U-Boot image... OK

WARNING: The new boot firmware will take effect when the system is rebooted.

root@srx% reboot

• Verify the Upgrade after reboot:

root@srx> show system firmware

Part                       Type        Tag    Current   Available   Status

                                                      version    version

Routing Engine 0 RE BIOS    0           3.10        3.6             OK