[U-Boot-Users] 5282 u-boot shadowing

Zachary Landau kapheine at gmail.com
Tue Mar 15 19:33:40 CET 2005

On Tue, 15 Mar 2005 11:50:34 -0600, NZG <ngustavson at emacinc.com> wrote:
> I'm working on getting u-boot up and running, pre-loader less, for the 5282.
> I've run into a few issues with the way things are currently done and I wanted
> to run some alternatives past the list to make sure I'm not violating any
> u-boot standards.

Maybe you didn't get my previous email to you about this.  I got the
5282 running pre-loader less in u-boot.  Some of the necessary changes
I have posted as patches to the mailing list.  A few of the changes
(like for the FLASH support) required some changes that changed u-boot
too much, so they still need to be reworked.  It still has some
issues, so don't expect all of this to work right away.   My webspace
isn't working properly, so I'll put the code up there a bit later.

> 1. The m68k code currently copies it's flash to DRAM at it's final location,
> then jumps to DRAM.
> To do it this way, the DRAM cannot be located at 0, as initializing the RAM
> there will shadow the Flash before the code has been copied.

I have the linker setup the flash at 0xf0000000.  When booting up,
before setting the FLASHBAR, the flash is seen as being at 0x0.  So,
first, I jump to 0x400 instead of 0xf000400.  I then copy into the
internal SRAM code to set the flash bar and then jump to the proper
location.  There may be a cleaner way, but that worked for me.  I'll
attach cpu/mcf52x2/start.S so you can see how I did it.

Zachary P. Landau <kapheine at gmail.com>
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