[U-Boot-Users] why the "rm der" instructions before and after erase flash?

[Wolfgang Denk]

In message <Pine.LNX.4.61.0503171405050.26401 at localhost.localdomain> you wrote:
> 
>   the only thing i'm unsure of in the instructions are the two
> commands:

Ignore those unless you are using a really old version of the BDI2000
firmware.

>   rm der 0x2006000f
>   ... erase and flash ...
>   rm der 0x2002000f
> 
> assuming this means modify debug enable register, what does the above
> represent?  i've flashed the PC loader a zillion times without ever
> having to modify this register.  is this something i'd only need with
> u-boot?

These instructions enable / disable the SYSIE bit in the  DER,  which
means  they  change  the  behaviour of the BDI if it traps into debug
mode on systemcall interrupts or not. The fast flash programming code
of the BDI (when using WORKSPACE) uses systemcalls to  terminate  and
re-enter  debug  mode.  Current  versions of the BDI2000 firmware set
this bit internally as needed for flash programming, but if you  test
firmware  that is older than March 2001 you may find that this is not
the case. Then you will NEED these "rm  der"  instructions.  [If  you
don't  need  them,  they  don't hurt either, so they were left in the
documentation.]

Best regards,

Wolfgang Denk

-- 
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