[U-Boot-Users] How to specify the size of bin?

[Stefan Roese]

On Friday 16 May 2008, 甜瓜 wrote:
> > All Walnut boards have 512k of NOR FLASH. Do you really have an original
> > IBM/AMCC Walnut or a different custom 405GP board?
>
> Yes, my board is a custom board DHT-Walut with 32MB SDRAM and
> 512k of boot flash AMD 29LV040B. Details are listed in:
>     http://elinux.org/DHT-Walnut

OK.

> >> I wonder
> >> how to build a 512KB bin?
> >
> > Generally this is possible. You need to change CONFIG_MONITOR_LEN &
> > CFG_MONITOR_BASE in include/configs/walnut.h. And TEXT_BASE in
> > board/amcc/walnut/config.mk.
>
> Thank you very much. That's exact what I need!

Noooo! Please wait.

> >> Is there any OPTION/SETTING targeting this
> >> problem? Anything else
> >> I should take care?
> >
> > But please don't forget that the environment is also stored in the NOR
> > FLASH. And by changing the U-Boot size to 512k you leave no space for the
> > environment.
>
> Do you mean that environment settings (eg: ip_addr, ethaddr...) are
> stored sperately
> from the bin?

Most of the boards do it this way, yes.

> In my mind (with guess :p), env should be defined in bin 
> code or data
> section, and it will be compiled together with other codes to form a single
> bin.

This can be done too. But its not the case on Walnut.

> > So why exactly do you want to change the U-Boot image size?
>
> Well. The reason is:
> 1. Both default config of u-boot and a DHT-Walut-patched config
> generate 256KB bin,
> but the flash on board is 512KB. So I think I should get a 512KB bin
> for flash writing.

No. You definitely don't need a 512k image for this setup. You just need to 
flash the image at the "end" of the FLASH chip. So starting at 256k:

0...256k:	Free and environment
256k...512k:	U-Boot image

> 2. The contents in the flash on my board is totally corrupted by
> accident. It means
> the important last-4-bytes should be rewritten to a proper state.
> 3. Currenly, I have to use special hardware to write bin into flash.
> Therefore 256KB bin
> will only overwrite the first half. The last-4-bytes in the end of
> flash is still the old value.
> Booting will definitely fail.

See above. Don't increase the image size, but flash it with an offset of 256k.

Best regards,
Stefan

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