[U-Boot] environment variables crc

[Gerrit Van Damme <gvd@mgb-tech.com>]

Mike Frysinger wrote:
> On Monday 20 April 2009 11:46:22 Gerrit Van Damme wrote:
>   
>> I've copied a flash image of one board to another one and changed the
>> ethaddr (environment variable)
>> of course when I start Uboot now the system says: CRC bad, using default
>> environment variables.
>> Now what I would like to do is recalculate that CRC, change it in the
>> image and then copy it to the second board.
>> Can anyone tell me how I can calculate the CRC and where it is located.
>> I already understood that it's a CRC32.
>>     
>
> "saveenv".  the CRC is the first 4 bytes of the environment and is calculated 
> using the environment.
> -mike
>   
Hey Mike,

Thanks for your answer.

The saveenv command doesn't work for me because then the default env 
variables are stored and this is what I want to avoid.

It's already a good thing that I can see that the first 4 bytes really 
look like the CRC of the environment. So this was really helpfull info.
Now you tell me it's calculated using the environment. In the source 
code I found the env variables crc calculated for a size of ENV_SIZE, but
I was unable to see how it was defined. Do you have more info on this?

Is the environment data (for crc calculation) terminated by a certain 
char (or sequence of chars) ?

Thanks and regards,

Gerrit