New project: Non-JTAG CFE replacement on the WRT54G v5

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PostPosted: Sat Jun 17, 2006 5:44    Post subject: New project: Non-JTAG CFE replacement on the WRT54G v5 Reply with quote
http://www.bitsum.com/openwiking/owbase/ow.asp?WRT54G5%5FCFE

I've mentioned this idea at OpenWrt and Sveasoft, and now I'm mentioning it here. I am prepared to do the work myself, if there is any interest in it. I have no use for it myself, but I'd love to see all these people with v5's have a viable option -- perhaps then they'd quit filling the forums with their horrifying discovery that they have an incompatible router Wink.

Summary: This project is about creating a 'CFE Replacement Firmware' that is compatible with the VxWorks bootstrap. This CFE Replacement Firmeware, as its name suggests, would flash a new CFE on to the unit , then put the new CFE into failsafe mode, waiting for TFTP transfer of an appropriate linux distribution.

There is risk involved. If power is lost during the few seconds it takes to flash the new CFE, then the unit will be bricked and recoverable only by JTAG. However, as long as user's don't lose power (or pull the plug) in that very small window, all should be fine. Most users should be willing to take this risk.

To those who feel the v5 is worthless due to its lower ROM and RAM sizes: please refrain from posting your opinion in this thread. I've found my v5 with DD-WRT micro to be a quite cable device, but this thread is about this project, and not whether or not the v5 is a piece of junk or not. For those who do think its a piece of junk, consider that most/all of its problems are due to the buggy firmware ... not its limited ROM/RAM.
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PostPosted: Sat Jun 17, 2006 10:23    Post subject: need vxworks bootloader.. Reply with quote
I took the time to install permanent/proper JTAG and RS232 ports on my v5 to prepare for this project, in case it starts to go somewhere.

UPDATE: I found my old whole flash backup of the original WRT54Gv5 VxWorks bootstrap and OS. Provided it's in-tact, I'll be able to begin work when I get a chance.

Now, does anyone care?
BrainSlayer
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PostPosted: Sat Jun 17, 2006 11:42    Post subject: Reply with quote
i could show you how todo it just with the serial.
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BrainSlayer
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PostPosted: Sat Jun 17, 2006 11:44    Post subject: Reply with quote
i dont know who created this site. but the openwrt developers are interested too in it and in general we have all informations todo this task. we know how the checksum works, we know how the vxworks bootloaders works. but currently no one has the time to spend some days in a overtaking firmware
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Matthiaz
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PostPosted: Sat Jun 17, 2006 11:44    Post subject: Reply with quote
Well, you go ahead. If it works that'll be cool. But I have serious doubts about it...

Besides, as you already mentioned: there are far better routers on the market as the v5, so I'd presume that this is a senseless piece of work.
BrainSlayer
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PostPosted: Sat Jun 17, 2006 11:46    Post subject: Reply with quote
this is true too. personally i want more to force the people to buy better products which even forces the industry to buy linux compatible routers. the micro for the v5 was more or less a gift, created in less than a day
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effojyaj
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PostPosted: Sat Jun 17, 2006 17:21    Post subject: reason to make v5 dd-wrt able Reply with quote
Linksys has started substituting v5 in rma replacements for all other versions. I believe they've even "neglected" to put a line item for the gl in the rma page, meaning they're going to replace wrt54gl with gv5, the bastards.

Given how often the damn things break, I might end up with 10 v5s.

I have taken brainslayer's advice and will not be buying any more linksys products until they make this THEIR problem and not mine.

Jay Joffe
mahenry
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PostPosted: Sat Jun 17, 2006 22:01    Post subject: Reply with quote
Yes. I, too, have taken BS's advice, and purchased a Buffalo router (whr-g54s). I agree whole-heartedly that Linksys should not be rewarded for effectively gutting out their routers with the advent of version 5 of the wrt54g(s) line.

Still, I have a v5 on my shelf collecting dust right now, and I would definitely flash it to the dd-wrt micro if there became a way to do so that did not require the use of a jtag cable. So if db90h is willing to spend the time to do so, I say go for it--and many thanks, in advance!

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PostPosted: Sat Jun 17, 2006 22:12    Post subject: Reply with quote
I created that site, so I'll update it to refect what you told me about the OpenWrt developers' interest. They had seemed so anti-v5 with their "its a waste of time to try" comments that I just assumed they had no interest, but perhaps that isn't a homogenous opinion Wink.

Brainslayer, so you guys already know the image format of the VxWorks HTTP firmware upgrade is expecting? Where are you at? Are you working on creating a firmware to replace the CFE, or creating a firmware compatible with the VxWorks bootstrap?

I'll search around for information already compiled on this subject, but if you have any information you would like to post to/for me, please do Wink. I would hate to avoid duplication of work, and also hate to go to more trouble than I have to ;p.

I'll revert to VxWorks tonight and begin playing around.

Thanks Wink.




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PostPosted: Sun Jun 18, 2006 4:58    Post subject: Reply with quote
I've learned a lot about what's needed for this project. It's totally feasible.

@Brainslayer: Yes, I figured out how to load kernels through serial initiated TFTP transfer, it'll be helpful during testing for sure.

I've looked into the format of the HTTP based firmware images. They are a fairly simple header, followed by an ELF. I suppose simply creating an appropriate header and appending it to the vmlinux ELF ought to do the trick.. though I am still researching this. Keeping in mind that I'm still relatively new to linux development, there's bound to be some mis-steps I take here.

Fortunately, much work has already been done by OpenWrt, ala the WGT624.

Now.. I must discover the header format and checksum locations and algorithms. Brainslayer, do you know these already?




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PostPosted: Sun Jun 18, 2006 6:55    Post subject: whoop Reply with quote
The 512 byte header seems very simple. I'm still playing with it now.




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PostPosted: Sun Jun 18, 2006 9:55    Post subject: ah... Reply with quote
Finally, found a reference to the checksum ... dunno if it's accurate, but just knowing the algorithm is all I needed. I can figure out the rest.

"The firmware format itself seems rather trivial. It's just an elf file with a few bytes of version info and a checksum before it. The checksum is the same as the one used in TRX (offset 0x100 or 0x200, iirc).
Since the boot loader does not do real 'boot_wait', it would probably be best to construct a 'takeover' image that - on first flash - will read the mac address and replace the VxWorks boot loader with a working CFE version.
The whole process doesn't seem that hard to do, and I would probably already have ported OpenWrt to it, if i had the hardware..."

.. and now I see what to call this project, a 'takeover firmware' ;p.




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PostPosted: Sun Jun 18, 2006 11:55    Post subject: Reply with quote
Ok.. now I've reached my the point where I need some guidance, else I'll be on this task for much, much longer:

* Is the vmlinux ELF output by the OpenWrt build ok to use (assuming enough stuff has been clipped out of the build)?
* If so.. should I sstrip the vmlinux? Otherwise, its ending up too big.
* I think the ELF following the header is a vmlinuz image.. am I right? Do I need to compress this vmlinux into vmlinuz?
* Any other guidance?

Thanks
BrainSlayer
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PostPosted: Sun Jun 18, 2006 20:03    Post subject: Reply with quote
standard vmlinux elf will work yes and stripping of the image is usefull too. keep me up to date with it. it would be a nice help. if you wrote a takeover image i will take this work to construct a real working dd-wrt based on the vxworks bootloader. any help is welcome since i'm busy with rb532 development in the last days
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Skywave
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PostPosted: Sun Jun 18, 2006 20:28    Post subject: Reply with quote
Just wanna say guys. KEEP UP THE GOOD WORK

Btw can someone confirm that they don't RMA WRT54GL but give you back a V5? If this true, then i will never buy Linksys again! In live in the Netherlands
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