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JTAG with broken serial Rx

Posted by nielsek 
JTAG with broken serial Rx
February 20, 2011 04:50AM

During bricking my Dockstar, I was somehow able to break serail Rx (input). After booting with JTAG into uboot (uboot-original-mtd0.kwb) I can see status through serial cable, but it's offline (not accepting commands).
The same cable and same configuration works with my other dockstar.
What do you think, it this end for this dockstar, or are there any chances to send commands through JTAG/telnet 4444? At least so far, that I could get the eth interface up?

Thanks in advance!
Re: JTAG with broken serial Rx
February 21, 2011 12:54PM
Just an idea, maybe someone can give me thoughts, if it's possible.
Jeff's uboot can be accessed by netconsole. For this with (fw_)setenv some values have to be set.
I made this on my other dockstar, and made a backup of mtd0 with nanddump. Then I loaded this image through openocd to the broken dockstar. Somehow still I wasn't able to access the uboot through netconsole. Is this idea practically right? Are the environment values in mtd0?

Thanks in advance,
John Doe
Re: JTAG with broken serial Rx
February 21, 2011 01:21PM
The boot loader itself and its configuration (as well as the configuration of the original boot loader) are in MTD0, which is the first megabyte of flash memory.

Note that the Ethernet hardware address (MAC address) is part of the boot loader configuration. If you clone the MTD0 area, you end up with two identical Ethernet interfaces on your network, which isn't going to work. Other than that, I'd expect it to work.

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