[U-Boot-Users] Porting u-boot, using emulator, run from SDRAM

Wolfgang Denk wd at denx.de
Mon Feb 24 23:03:58 CET 2003

In message <3E5A1DB4.5040909 at esk.fhg.de> you wrote:
> we try to get u-boot running on an Infineon Switch Evaluation Board
> (MXU rev.B, MPC850). There is a VxWorks image in FLASH which is starting
> and running correct.

make a backup, erase it, and install U-Boot in it's place.

> We would like to stop the start of the VxWorks image with our Lauterbach
> Emulator and then laod the u-boot bootloader into SDRAM and start
> u-boot. This is already done (our script for Lauterbach works).

If you want to use U-Boot, there is no reason  to  keep  the  VxWorks
bootloader; U-Boot can boot VxWorks images, too.

> We started with the tqm850L configuration (u-boot 0.2.0), successively
> changing/ commenting things. We already managed to modify the u-boot
> code, so that we get to the u-boot command prompt, where we can enter
> commands. Unfortunately we just hacked around and didn't really
> understand well how the u-boot code could be adapted to our board.

Then restart from scratch, and do it properly this time.

> Commenting out some RAM/FLASH size check routines and clock
> discovery routines leads to not properly filled structures.

Among other potential problems.

> - Is there a simple #define switch to support u-boot running from SDRAM,
>    loaded into RAM with an emulator? - I think this would be a nice

No there is not.

>    feature in order to port the u-boot code to a new board.

This is a matter of style. I always find it much easier to get things
working in the same sequence as they  happen  in  reality.  And  this
means  to  start  it from the boot device as addressed by /CS0, i. e.
usually from flash.

> - E.g. reading manufacturer ID of FLASH doesn't work at all. We also
>    didn't manage to read this ID with issuing FLASH writes/reads from
>    Emulator. But using the VxWorks boot prompt commands it works.

Seems your (modified?) version of the flash driver does not atch your
hardware. Fix it.

> Maybe someone has some suggestions on how to go on.

As mentioned above: restart from scratch, and do it  again  properly,
step  by step. Don't focus on getting a "running system" with command
prompt and everything first - solve the problems in the sequence they
pop up. The rest will automatically fall in place.

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
Too much of anything, even love, isn't necessarily a good thing.
	-- Kirk, "The Trouble with Tribbles", stardate 4525.6

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