So you're afraid you will ever need to use a backup of your CFE (bootloader) in case you brick your router sooner or later.
If you own a Linksys WRT54G/GL/GS and your CFE is already screwed, you could try the Skynet repairkit to make yourself a new one. CFEs for these and other various models may also be found at CFE collection project.
There are several methods to backup the CFE, as follows:
by web interface
this is working with dd-wrt post RC5 svn8428
backing up your cfe is easy, all you need to do is to point your browser to:
this maybe works on other 3rd party firmwares, too. connect to the router via telnet or ssh (SSH must be enabled!)
just enter the following command for all, except dd-wrt micro builds:
dd if=/dev/mtd/0 of=/tmp/cfe.bin
With v24 (mini and mega), paste that line into the Commands box on the Administration/Commands tab (Diagnostics.asp), and click the Run Commands button.
Then get the cfe.bin file from the /tmp directory with FTP, SFTP or SCP (using, for example, WinSCP).
On micro builds it's little more tricky:
cat /dev/mtd/0 > /tmp/www/cfe.jpg
Then point your browser to http://routerip/user/cfe.jpg and do a "save page as" cfe.bin to your disk drive. The resulting file should be 256K in size for a cfe.bin file.
Note: "/user/cfe.jpg" points to "/tmp/www/cfe.jpg"
You could do the same for mtd/1 (kernel, firmware), mtd/2 (jffs part if any) and mtd/3 (nvram)
this assumes you already have a JTAG-Adapter cable ready to use on your router, use the following command:
you can do the same with the nvram, kernel, etc.
Restoring the CFE
WARNING: Do not attempt to restore the CFE by telnet/SSH unless you know what you are doing and why you are doing it. If done incorrectly, this could render your router unbootable!
The following was tested and working on wl-500gp:
First copy your CFE into router's /tmp directory (using something like WinSCP or wget), then
mtd unlock cfe
mtd write -f /tmp/cfe_new.bin cfe
Use JTAG to restore the unit's CFE. For example,
CFE compressors available for some neutered Linksys units
Many ask about the Micro_Plus builds. Check here for past discussion.
We now have the CFE compression routine finished for the following units. (more to follow in this thread...this top post will include updates as they come online)
[NOTE] - It has been found that if you run the compressor on the V5.X units...that you can NOT revert to Linksys BSP and Firmware using the Bitsum process for reversion. The only way to revert back to vxworks is to use JTAG to manually flash it back.....You have been warned!!! (02/06/09)
WRT54G2v1 - A compressor will not be available for the G2v1 - after installing dd-wrt, it already has a 128K CFE...it can run micro+ without updating the CFE
- Follow steps exactly as if you had a V8 model. The RAM settings will be automatically set for your 16M of RAM.
- this is NOT for the GSV7.0...this model is still untested and the CFE is different from the GSV7.2 so it may not work on a GSV7 model
- at this time...only a single GSv7.2 has been updated...use with caution...Brickage is still possible...please report any successes on the GSv7.2 units. (I'll then remove this message as more become updated)
Check back here for updates as we get them tested and made available.
[NOTE:] If using Mac/Linux for the tftp flash read this
[EDIT] - please don't ask about a specific model's availability...we will get them posted as we get them tested.