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3. Upgrading the firmware

This chapter explains how to upgrade the firmware to a newer version. To determine which version of the firmware you have, watch the screen when you power up your machine. There are three major releases of firmware currently `out there': the present series (2.0.x), the old stuff (1.3), and the really old stuff (less than 1.3). Anything pre-2.0 should be updated immediately. Depending on the existing firmware version number, the process for updating will vary slightly: consult the appropriate section below.

3.1 Obligatory warning

Please note that reprogramming the firmware is an inherently dangerous activity that could potentially render your NetWinder completely inoperative. Without the firmware, a NetWinder will not be able to boot itself. Before attempting to reprogram the firmware, back up all important files and prepare yourself for the possibility of having to return your machine for repair. Needless to say, firmware upgrades are done entirely at your own risk!

In practice the flash updating process is really quite safe. Follow the directions given here and things should work out fine. If this is your first attempt to update the firmware, please read this chapter completely before you begin. If you still have problems, you can ask for help on the mailing lists or newsgroups ( news:// Statistically speaking, the likelyhood of toasting your machine is less than 1%, based on the number of units returned with dead flashes in the last year.

3.2 Obtaining new firmware

New versions of the firmware can be obtained anonymously from and have filenames of the form nettrom-X.Y.Z.bin where X.Y.Z is the version number. Be sure to use binary mode when downloading the file. At the time of this writing, the current stable nettrom version is 2.1.24. More recent development versions can also be found elsewhere on the ftp site (hint: look in Rod Stewart's or Andrew Mileski's directory), but beware that these may not have been extensively tested - and you probably don't own JTAG equipment (just thought I'd remind you).

Some of the nettrom binaries are available with an attached `rescue' filesystem. Especially for those people with small hard disks in their NetWinders, this rescue filesystem is helpful for restoring or updating the disk image. Therefore it is recommended that you use a nettrom+rescue image when one is available. The only times you'd really want to use a non-rescue image is when you plan to create your own flashroot filesystem (see the `Advanced booting' chapter for details).

Checksum verification

You may wish to use the md5sum command to generate a checksum of the nettrom image you've downloaded to ensure there were no errors in the process. This is important because the flash writing program has no way of knowing if the nettrom binary is valid or not - it simply copies the file into the flash memory. To compute the checksum, issue the command

        md5sum nettrom-2.0.X.bin

where nettrom-2.0.X.bin should be replaced with the name of the file you've downloaded. Very old NetWinders may not have the md5sum program, in which case you cross your fingers and hope for the best. Otherwise, the computed checksum should be compared against those listed in If the checksums don't match exactly, delete the nettrom.bin and transfer it again. Check that your FTP client is doing a binary transfer, not an ASCII or text transfer.

3.3 Writing the flash

The next step is to transfer the nettrom.bin to the actual flash memory chip. This is done using a program called flashwrite, which in turn depends on a kernel module called nwflash.o (on older systems, it was called flash.o). The exact process varies slightly depending on the age of the software on your machine; consult the appropriate sub-section.

You must be logged in as root to reprogram the flash, and should not be running any unecessary programs at the time. The flash writing process is very sensitive to timing and might fail if an interrupt occurs at the wrong moment. Before you begin, it is suggested that you unplug any network cables or peripherals, and terminate any active tasks. In other words, the machine should be loaded as lightly as possible.

Once the flash writing process has been started, it should not be interrupted. Should an error be detected, it is important that you do not reboot the machine under any circumstances, since the contents of the flash memory are uncertain. Repeat the flash writing process until it succeeds. Consult the troubleshooting section, below, if any errors are encountered.

Recent machines

Recent disk images already contain all the tools necessary to update the flash memory. Simply download a nettrom binary from the ftp site and then run the following commands to update the flash memory:

        insmod nwflash
        flashwrite -base64 nettrom-2.0.X.bin 0

Replace nettrom-2.0.X.bin with the name of the nettrom file you downloaded. By convention, the nettrom binary is normally stored in the /boot directory but you can put it wherever you wish - you'll have to specify the path accordingly in the flashwrite command. Remember that once the flashwrite has started, it must complete successfully before you reboot the machine.

Also note that the final character in the flashwrite command line is a zero, not the letter `o'. This parameter specifies the offset from the beginning of the flash memory - in this case, the data is being written to the beginning of the flash.

Older machines

The process for older machines is pretty similar to that of recent machines (see preceeding section), except the nwflash driver is called flash and it uses different major/minor numbers. The commands to be typed are therefore:

        insmod flash
        flashwrite -base64 nettrom-2.0.X.bin 0

The older flash driver is more susceptible to failure, so be sure to repeat the flashwrite command if it fails to write the whole nettrom image. Consult the troubleshooting section below if you have any problems.

Really old machines

On really old machines, the flashwrite program and the flash driver are not included, since they were changing so often at that time. In this case, it is recommened that you download nettrom-1.3pl4.tar.gz in addition to the nettrom-2.0.X.bin file. The tar.gz file contains all the necessary programs for writing the flash, along with the 1.3pl4 version of nettrom. This old nettrom should be deleted and the 2.0.X version used in its place:

        tar zxvf nettrom-1.3pl4.tar.gz
        cd nettrom-1.3pl4
        rm nettrom
        cp ../nettrom-2.0.X.bin nettrom.bin

Now the flash can be written in much the same manner as before. The only difference really is that the commands are not on the normal search path, so they must be preceded with `./' so they can be found:

        ./insmod flash.o
        ./flashwrite -base64 nettrom.bin 0

As in the case for `older machines', this version of flashwrite is not very rubust and several tries may be necessary until the entire flash image is successfully written.

3.4 Troubleshooting

Problems during the flash writing process can be attributed to either the insmod or the flashwrite commands. Obviously, a failure in the former command will also lead to failure of the latter. If the error message doesn't make it clear, you can use the lsmod command to verify what modules are loaded. If the nwflash or flash device is not listed, then the insmod failed. Otherwise, check the flashwrite command.

insmod problems

Problems with insmod fall in two categories: either the executable cannot be found, or the flash module can't be found. In the former case, try including the full path, ie. /sbin/insmod. Otherwise, the problem is with the flash module. Try both flash and nwflash as the module name. Failing that, try looking for the flash module with a command like find /lib/modules -name '*flash.o' and then use the resulting full path name as the module name.

It's also possible to get an error from insmod about a kernel version mismatch. This means that the specified flash module is not compatible with the kernel. Check to see if any other flash modules are available, using the find command described above. If not, you can try using the -f flag to insmod, to force loading of the module. If all else fails, download the nettrom-1.3pl4.tar.gz file and consult the instructions for `Really old machines' above.

flashwrite problems

The most common problem with flashwrite is typing in the command incorrectly, or not specifying the name of the nettrom.bin file correctly. If the nettrom.bin file is not in the current directory, then the relative or absolute pathname must be specified. And following the filename, there must be a zero (as shown in the previous section's examples).

An error message along the lines of `Can't open /dev/flash' indicates that either the flash module wasn't loaded correctly (you can check this with the lsmod command), or there is a problem with the device entries. The proper value for the device entries depends on which module you are using: for flash the major/minor numbers are 101 and 0, whereas for nwflash the numbers are 10 and 160. To set the device nodes up, use the following commands, substituting the appropriate numbers for MAJOR and MINOR, respectively.

        cd /dev
        rm *flash
        mknod -m644 flash c MAJOR MINOR
        ln -s nwflash flash

Any other errors from flashwrite indicate a real problem writing to the flash memory. If this condition persists, try loading the flash driver with debugging turned on: first do rmmod flash, then repeat the insmod command with flashdebug=1 suffixed on.

3.5 After writing the flash

Once the flashwrite program completes, the update is pretty much done. Ensure that the number of bytes written matches the size of the nettrom.bin file you were writing. If the numbers do not match, repeat the flashwrite process again. Otherwise, it is safe to shut down the machine (using CTRL-ALT-DEL for example) and upon reboot the new firmware will be active.

If you are paranoid, you can perform one more test before you reboot. The data can be read back from the flash memory and be compared with the original nettrom.bin file. It's pretty unlikely for any discrepancies to turn up, since flashwrite already performs such checking, but it doesn't hurt either. You need to know the size in bytes of the nettrom.bin file you just flashed.

        dd if=/dev/nwflash of=actual.nettrom bs=1 count=BYTESIZE
        cmp nettrom-2.0.X.bin actual.nettrom

Replace /dev/nwflash with /dev/flash if you've got an `older' system, and substitute the actual file size for BYTESIZE. There should be no output from the cmp command; if there is, go back and repeat the entire flash writing process. Keep in mind that this test only verifies that the file was written correctly to the flash, but it cannot protect against having an invalid file in the first place.

3.6 The first reboot

Now it's time to perform ancient tribal rituals (or just cross your fingers) and reboot your machine. With luck, you'll see the white banner screen with the new firmware version number displayed. Shortly thereafter you should see the `Press any key to abort autoboot' message. Getting that far indicates that your flash reprogramming was successful.

The first time you boot a new version of firmware, it is a good idea to issue the commands load-defaults followed by save-all. If you don't do this, your old settings will be preserved, but you may see a warning message whenever you enter the firmware menu, and it is possible for there to be some odd side-effects.

Upgrading from pre-2.0 firmware

If you've just upgraded from pre-2.0 firmware, then some special considerations apply. The default parameters in 2.0 firmware assume that the disk is partitioned with /dev/hda1 as the root filesystem, and that the kernel is also contained on that partition. However, the 1.3 firmware used a different setup - /dev/hda1 was a dedicated kernel partition, and the root filesystem resided on /dev/hda2. It is recommeded to update to the new layout, but that is outside the scope of this document. In order to boot the old-style layout with 2.0 firmware, the following command sequence should be issued the first time you boot up:

        setenv kernconfig partition
        setenv rootdev /dev/hda2

It is recommended that you stop using this partition-based boot method, since it is difficult to recover from a bad kernel. If you don't want to repartition and re-install your whole system, you can still switch to the new boot method. Simply install a NetWinder kernel into the /boot directory on your system and instruct the firmware to boot it:

        setenv kernconfig fs
        setenv kerndev /dev/hda2
        setenv kernfile /boot/vmlinux
        setenv rootdev /dev/hda2

With this setup, you can install many different kernels in /boot and switch between them by changing the kernfile parameter.

3.7 If it doesn't work...

... Don't panic! In some cases you may still be able to rescue the machine. If the first 32 kB of flash are still intact, then it is possible to serially download a kernel and boot it. Then the flash memory can be reprogrammed again, hopefully with a working image this time!

A second computer is required, along with a null-modem cable. Such a cable can be had at most computer stores, or you can make your own (see the Serial-HOWTO for details). The cable should connect between the serial port on the NetWinder and the serial port on the rescue system.

Next, a terminal program should be launched on the rescue system. It should be configured for 19200 bps, 8 data bits, no parity, and 1 stop bit (For firmware 2.0.8h and beyond, the speed is 115200 bps). Be sure to turn off any handshaking, both hardware and software. Then turn on or reboot the NetWinder - a number of diagnostic messages should be printed on the serial terminal. If you see nothing, check the cables and the COM port settings. If you really don't get any output, then you flash is truly wrecked, and you'll have to return your machine for repair. Sorry.

Otherwise, you should see the message `Press * TWICE to abort autoboot' or similar. Some older versions of the firmware used ALT-D instead of an asterisk character. Press the appropriate key, and a Nettrom control menu will appear. You can press `?' for a brief listing of available commands.

The next step is to obtain a NetWinder kernel and put it on the rescue system. If you have older firmware and a 2.0 kernel, please skip down to the next sub-section for further instructions. The "z" option described below is also available in newer firmware versions, but the new "x" option is considerably nicer.

        x c000

The firmware is now expecting a kernel to be transmitted in Xmodem format. Use your terminal program to transmit the file (in minicom the command is ALT-S). You may have to repeat the x command since it times out after a short period.

The kernel should download in about 2 minutes at 115200 bps. Once it is done, use the command j c000 to start the kernel. If you wish to change the root device from the default of /dev/hda1 (major 3, minor 1), it must be done before the "j" command. Use d 100 and note that location 110 contains 0301. Change this to the value you want using the e 110 command.

Older firmware and 2.0 kernels

The official 2.0.x kernels from the ftp site cannot be used directly because they are in ELF format - but the firmware only knows how to deal with an a.out kernel. The vmelf utility program ( can be used to convert an ELF kernel into a.out form (well, close enough anyways). Just type make vmelf to build an executable from the vmelf.c source code. It's a hack.

Record the size of the kernel file - it will typically be somewhere between 870000 and 1250000 bytes. Convert the size from decimal into hexadecimal (sorry, that's all the nettrom menu knows about) and write it down. Now, at the Nettrom prompt, use the `z' command to load the kernel. The arguments are two hexadecimal numbers - the first is always c000, and the second should be the size in hex of the kernel file. Don't include the `0x' or `$' symbols in the size value.

        z c000 HEXSIZE

Use the `upload' feature of your terminal program to actually transmit the kernel file. Notice that the file must be transmitted `plain binary', meaning that there is no protocol (like xmodem, zmodem, or kermit). It just a raw stream of bytes. This also means there is no error checking. Note that as of firmware 2.0.8, Xmodem is supported; see above for details.

The transmission will take about 10 minutes at 19200 baud. A series of asterisks will be printed as the transfer proceeds. (Yes, there is an option to change the baud rate, but it doesn't work as you would expect. It's best just to stick with the standard rate and wait. After all you should only ever need to do this once). Upon completion of the download, the Nettrom prompt should re-appear. If there is no prompt, or there are lots of extra characters after the Nettrom prompt, then something got out-of-sync during the download. In this case, you'll probably have to repeat the whole process. But it doesn't hurt to try to boot the kernel anyhow - you might get lucky. The following command will boot the kernel:

        j c000

Hopefully your machine should boot up fine now, and you can go and reprogram the firmware properly. There is no way to pass a command line to the kernel, so the compiled-in default values will be used. Usually the defaults are 16 megs of RAM and a root device of /dev/hda1 - this should boot most machines. If your setup differs, you can hack different values into the kernel file before you send it down the serial cable. Kernels as of 990121 use a param_struct (defined in include/asm-arm/setup.h) for passing in the various boot-time parameters. It is possible to modify this structure using the Nettrom debugger commands (type `?' for help at the nettrom prompt). The structure is stored at memory location 0x100.

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