[U-Boot-Users] problem when running the bootm command

[Erez Koelewyn]

On 10/23/07, Jerry Van Baren <gerald.vanbaren at ge.com> wrote:
> It sounds like your linux image is scribbling in flash, messing up
> u-boot (but not fatally).  Do you have a flash file system configured in
> your linux image?  Any other reason your linux image would overwrite
> flash?  If you dump the end portion of the *flash* u-boot image before
> and after the successful linux boot, does it show corruption?

I never thoughtLinux might be corrupting FLASH memory for the following reasons:

1. When I load and run linux as a .bin file there is never any
problem. Ah! yes, another good test would be to run load and run a
linux .bin file (on a freshly programmed board) and after that try to
inflate a packaged linux image.
2. Flash memory sectors where U-Boot resides are protected (read
only). Could linux be removing the protection? I should check.
3. The problem occurs even when uncompressing from a RAM location to
another RAM location, before linux has a chance to run. But obviously
the corruption could still happen in the first run as you pointed out.

I will do as you suggest and compare the FLASH memory dump with my
U-Boot image, it's a very good idea.

> If that isn't the problem the follow up question is: what is the
> unexpected exception vector number 3, what is the meaning of the PC
> (where the exception occurred), what does the stack tell you when you
> dump it?

Yes, that's the hard part. I was hoping to aviod the hassle in case
someone already encountered this problem and provided a patch (I
couldn't find anything in previous postings though).

Thank you for your advice,

Erez