[U-Boot] Support required for loading U-boot on SDRAM

[Stefan Roese <sr@denx.de>]

Hi Sadashiv,

On 28.03.2013 16:11, Sadashiva Reddy wrote:
> I am using AMCC PPC440Gx processor for our project presently the board
> is working fine with vxWorks(BSP + OS + Application).
> But our customer new requirement is same board should be ported with linux.
> 
> 
> 1. We are using BDI2000 JTAG tool for porting u-boot and kernel.
> 
> 2. We are not able to load the u-boot or u-boot.bin file directly
> to SDRAM location.

Yes, this will not work. In general "u-boot.bin" is a binary only for
programming into flash. Some 4xx variants support an RAMbooting build
target though (e.g. 440EPx). Please take a look at this define
CONFIG_SYS_RAMBOOT. This is not ported to 440GX though at the moment.

> 3. When we try to load its load to the flash loaction i.e what ever we mention in the macro  
>     CONFIG_SYS_TEXT_BASE from board.h file its loads to that location and when we 
>     give go command it throws an error called JTAG instruction overrun.
> 
> 4. When we build the u-boot code the file size of u-boot.bin is always created with the macro 
>     initialized by CONFIG_SYS_TEXT_BASE from the board.h file.
> 
> 5. We are able to load u-boot.bin to a flash location directly but u-boot is not coming up.
>     So to debug the u-boot we are trying to load directly to SDRAM location. VxWorks is 
>     coming up when we load directly to SDRAM location. 
>     
> 6. I think the u-boot is creating a u-boot.bin file to load for flash loaction. How to create an 
>     image or bin file to load on SDRAM location directly.

Please see my comment above. You either need to create a real U-Boot
port for your custom 440GX board to program into flash. Or you can also
port the CONFIG_SYS_RAMBOOT feature to 440GX to support RAMbooting. But
this would only help for test purposes. I suggest that you port the
"real" U-Boot to your board.

Thanks,
Stefan