E750 - how to access U-Boot console?

Technical Support for Routers
1

Hello,

I messed up my E750 and now it won't boot. I did the Debrick instructions and I can access the web interface where I could re-flash it.

However, I need to get some file off of the device before I reinstall... How can I get to an actual U-Boot console with text instead of web gui?

Wireshark shows the E750 is 192.168.1.1 and is doing ARP for 192.168.1.2 and I thought maybe I could tftp boot an image from 192.168.1.2 or something. But even when I set my computer IP to 192.168.1.2, the E750 doesn't care, it just keeps ARP requesting and ignoring my computer's ARP reply.

The original pepe2k U-Boot github says there is a Network Console but nothing happens when I try to communicate on UDP 6666. I can see in Wireshark my packets going out from the computer but the E750 does not reply.

Maybe I would need to set some U-Boot environment variable differently. but I cannot do that as I cannot get to a U-Boot console...

2

How did you messed it up?

3

I think I installed a bad driver.

Do you know if it is possible to get into U-Boot?

4

If Debrick via Uboot - GL.iNet Router Docs 4 does not work, I don't know what else you can do right now. :frowning:

5

This does work, but I don't want to do it because it will replace the filesystem and I want to get my files out of it. :frowning:

This is what happens when I have it in recovery mode. You can see the E750 looking for 192.168.1.2 and you can see my computer replying that it is 192.168.1.2 but then the E750 does not do anything, it just asks again and again...

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6

Did you install plain OpenWrt maybe?

Afaik Uboot isn't capable of providing access to your files anyway. It's just for opening the web interface to reflash the software.

7

You are right, U-Boot cannot directly provide access to my files (at least not easily).

But there is an option in U-Boot to do a net-boot with tftp. The device will download a bare-bones kernel image into memory without overwriting the flash, then boot into that.

Then I can mount the filesystem access my files. So that is what I need access to the real U-Boot console for.

On other devices with OpenWrt, you can usually access the real U-Boot with a UART serial cable, but as far as I am aware, there is no UART port on the E750.

Thus this question. The capability exists within the pepe2k U-Boot -- I am just having trouble getting it to work.

8

The Uboot environment used by GL is customized, afaik. I am not sure if the capability still exists - does not seem like it.

9

The GL.iNet version is posted on their github and I don't see any reason why this shouldn't work... The code is still there.

10

@alzhao Any ideas?

11

netconsole is not in the uboot.

In very early of routers we tried netconsole. Maybe 9 years ago. It is cool but not really useful.

12

I see, thanks for the information.
Do you know of any way that I can do a tftp boot with the E750 without getting a netconsole, then?

13

I don't think you can do it.

14

Darn.

Can you think of any other way that I can recover my data before I re-flash it?