upslug2 man page

upslug2 — utility to upgrade the firmware of a NSLU2 via the network


upslug2 [options]


upslug2 is a command line program intended to allow the upgrade the firmware of a LinkSys NSLU2 (Network Storage Link for USB 2.0 Disk Drives) to new or different versions.  When a NSLU2 in the local network is put in upgrade mode, upslug2 can connect to it and upload a new firmware.

upslug2 will accept a full firmware image but it can also upgrade the flash from individual files holding the kernel, ramdisk and root filesystem. upslug2 provides status information during the upgrade process and verifies the written image after the upgrade.


-C, --Complete-reprogram

Reprogram the complete flash, including the RedBoot boot loader and the SysConf partition holding configuration information.  Using this option may result in the NSLU2 becoming permanently unusable!  By default, upslug2 will not touch these two partitions since this allows flashing a new firmware if an uploaded firmware does not work.  This is not possible if RedBoot itself is damaged.  Use with caution.

-d, --device

The network device on the host machine connected to the network on which the NSLU2 is located. (Default: eth0).

-e, --endian

The endianness of the files to be uploaded. upslug2 will usually detected the endianness automatically but this option can be used to force byte swapping to occur.  This option accepts three values, separated by comma: endianness of kernel, data and RedBoot FIS directory. Valid values are l (little endian), p (pdp endian) and b (big endian). (Default: ,b,b)

-f, --from

The MAC address of the host system.

-h, --help

Show summary of options.

-i, --image

The flash image to use.

-j, --rootfs

A root filesystem, usually of type jffs.

-k, --kernel

A compressed kernel zImage image.

-n, --no-reboot

Do not reboot after upgrade

-p, --payload

FIS directory payload.  There are about 140 Kb in the last block (between the FIS dir and the trailer at the end) which can be used for data.

-r, --ramdisk

A compressed ramdisk image.

-R, --ram-payload

A ram paylod (replaced ramdisk). (FIXME: if it replaced the ramdisk, why cannot you just use the -r option? What's the difference)

-t, --target

The MAC address of the NSLU2 to upgrade.  Without this option, upslug2 will only perform an upgrade if there is just one NSLU2 in upgrade mode.

-U, --no-verify

Do not verify the image, only upgrade.

-v, --verify

Do not write to flash, only verify the image.

Options to specify firmware information

The following options should be used when individual kernel, ramdisk and root filesystem files are specified rather than a firmware image.

-E, --extra-version

Extra version information, a 2 byte value. (Default: 0x90f7)

-F, --firmware-version

The firmware version, a 2 byte value. (Default: 0x2329)

-P, --product-id

The product ID, a 2 byte value. (Default: 1)

-T, --protocol-id

The protocol ID, a 2 byte value. (Default: 0)

Using Upslug2

In order to use upslug2 the NSLU2 which is to be upgraded has to be put in upgrade mode:

1. Disconnect any disks and/or devices from the USB ports.

2. Power off the NSLU2

3. Press and hold the reset button (accessible through the small hole on the back just above the power input).

4. Press and release the power button to power on the NSLU2.

5. Wait for 10 seconds watching the ready/status LED. After 10 seconds it will change from amber to red. Immediately release the reset button.

6. The NSLU2 ready/status LED will flash alternately red/green (there is a 1 second delay before the first green). The NSLU2 is now in upgrade mode.

If you decide not to flash the image the NSLU2 can be rebooted by disconnecting the power.  If the ready/status LED does not turn green after step four it will remain red for several seconds then flash amber. This happens if you do not release the reset button in time - pull the power, reconnect it and repeat from the second step.

Once the NSLU2 is in upgrade mode it will remain in this state until either the power is connected or a new image has been flashed. If the flash fails the NSLU2 will (eventually) return to upgrade mode


The most common use of upslug2 is the following:

upslug2 --image NSLU2_V23R63.bin

This specifies a firmware image which will be written to flash (with the exception of the RedBoot and SysConf partitions).

Alternatively, kernel, ramdisk and root filesystem can be specified individually:

upslug2 -k nslu2-zImage -r ramdisk -j root.jffs

In this case, the options -E, -F, -P and -T should typically be specified as well.

By default, upslug2 will search for the NSLU2 on the network on your eth0 network interface. If the network is on a different interface, you can easily specify it:

upslug2 -d eth1 --image NSLU2_V23R63.bin

If there are potentially more than one NSLU2 in your network which may be in upgrade mode, you can specify its MAC address:

upslug2 -t 00:11:85:12:34:56 --image NSLU2_V23R63.bin

See Also



John Bowler <>


January 2006