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

Wolfgang Denk wd at denx.de
Fri Mar 18 00:17:45 CET 2005

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

>   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

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
A Stanford research group advertised for participants in a  study  of
obsessive-compulsive  disorder. They were looking for therapy clients
who had been diagnosed with this disorder. The  response  was  grati-
fying;  they  got  3,000 responses about three days after the ad came
out. All from the same person.

More information about the U-Boot mailing list