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March 14, 2010 09:07 AM

Categories: WNR3500L

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Member Avatar

latdna

Member
Joined: 01/15/2010

If you backup cfe with this command: 

dd if=/dev/mtd/0 of=/tmp/cfe.bin

Open the file with hex editor, you can find this from it:

boot_wait=off wait_time=3, would it be possible change it to this: boot_wait=on and wait_time=10 for easyer recovery?

like with Linksys WRT54GL.

My cfe: http://dl.dropbox.com/u/2880566/cfe.rar

Links about CFE: 

http://www.dd-wrt.com/wiki/index.php/CFE_backup#Restoring_the_CFE

http://oldwiki.openwrt.org/OpenWrtDocs%282f%29Customizing%282f%29Firmware%282f%29CFE.html

Someone who has JTAG cable could maybe try this and if it works make some guide, i have no jtag cable or ttl header so if i crash the CFE even shortcuting those two pins on router to enable tftpd won't work.

Discussion:    Add a Comment | Comments 1-13 of 13 | Latest Comment

Tathagata Das Avatar
NETGEAR
March 16, 2010 5:32 AM

Through nvram command you possibly can change boot_wait and wait_time variables.

Generic Member Avatar
Member
March 16, 2010 5:43 AM

Well i have tryed that, not working. It won't either change it to cfe.

Tathagata Das Avatar
NETGEAR
March 16, 2010 7:01 AM

Where did you change it , from bootloader prompt or from console prompt ?
What were those commands that you executed ?

Generic Member Avatar
Member
March 16, 2010 7:10 AM

I enabled it like this:
nvram set boot_wait=on
nvram set boot_time=10
nvram commit

so its only on linux firmware nvram not on the cfe bootloader, i have no jtag so i don't know how i would enable it to there.

Tathagata Das Avatar
NETGEAR
March 16, 2010 8:17 AM

Execute those three commands in CFE prompt.

Generic Member Avatar
Member
March 16, 2010 8:24 AM

How i can get to CFE prompt without jtag cable?

Tathagata Das Avatar
NETGEAR
March 16, 2010 9:00 AM

You dont need to have jtag cable for that. All you need is a serial cable.
Through serial console (in linux it is minicom) press CTRL+c while power on. It will go to CFE prompt.

Generic Member Avatar
Member
March 16, 2010 9:17 AM

If you mean this: http://www.myopenrouter.com/article/13859/How-To-Debrick-Your-NETGEAR-WNR3500...

i have no TTL header where to connect it and soldering one would be hard and if i would have ttl header and that cable it would be kinda useless to enable tftp boot_wait :)

Evil.2000 Avatar
Member
March 23, 2010 8:35 AM

It is useless to enable boot_wait because the WNR3500L does NOT act like a Linksys WRT54G with starting a tftp server and waiting for a firmware. The WNR3500L tries to connect to a tftp server on 192.168.1.2 and requests an image called vmlinuz.

This looks to me like booting from network but not like grabbing a firmware and writing to the flash.

If you want to write a flash image to the device from CFE prompt you really need a serial cable. There's no way around this from my point of view.

Generic Member Avatar
Member
March 23, 2010 8:48 AM

Ok did you try enable boot_wait to cfe? not just only nvram? Well this is not anything very important since there is that shortcut pins method to get tftpd started and accept new firmware.

Evil.2000 Avatar
Member
March 23, 2010 8:55 AM

I enabled boot_wait like you in nvram.
Then the router acted like i described above...

Generic Member Avatar
Member
March 23, 2010 9:03 AM

Ok, well i talked about CFE(bootloader) it has option for boot_wait already but it's off. I think it has no support for reading it from nvram but if you get it enabled to CFE(bootloader) it would work and wait. Open it with hex editor and find boot_wait. http://dl.dropbox.com/u/2880566/cfe.rar

Evil.2000 Avatar
Member
March 23, 2010 10:09 AM updated: March 23, 2010 10:10 AM

I suppose the boot_wait that you see in the CFE partition is only a default value if the one in nvram is missing. The CFE bootloader is nvram capable and reads the boot_wait variable from nvram.

So changing the boot_wait flag in CFE will not change the behavior of the bootloader until the nvram partition is corrupted or empty.

See http://oldwiki.openwrt.org/OpenWrtDocs%282f%29Customizing%282f%29Firmware%282... under "Checking it"

Discussion:    Add a Comment | Back to Top | Comments 1-13 of 13 | Latest Comment

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