[U-Boot] [PATCH 0/4] Convert MPC85xx platforms to a single linker script

[Trent Piepho]

On Tue, 14 Oct 2008, Wolfgang Denk wrote:
> Dear Trent,
>
> In message <Pine.LNX.4.64.0810131610000.3399 at t2.domain.actdsltmp> you wrote:
>>
>> At this point all the mpc85xx linker scripts are exactly the same, except for
>> one line that defines the flash bank size, so they are combined into one
>> script in cpu/mpc85xx/u-boot.lds.  A common flash bank size that will work for
>> all boards is used.  If a board in the future needs something different
>
> Umm... This is not how it should be done.
>
> U-Boot should *never* assume  static  flash  bank  sizes.  The  whole
> design  is  based  on  the idea to automatically determine the actual
> size of flash and RAM that  is  fit  on  a  specific  board,  and  to
> auto-adjust for this.

The bank size here is only used for linking u-boot.  The actual u-boot code is
no different that it is now.

In order to boot on mpc85xx, the u-boot image must be linked to locate the
boot page as the last page in the flash bank.  There is no way to do this at
run time, it's the boot page.  All existing 85xx platforms hard code the
location of the boot page in the u-boot image one way or another.  I'm just
changing the linker script to do it in a way where the same script will work
on all 85xx boards.

Right now changing the u-boot image size and/or the boot flash bank mapping
requires changes to the linker script.  Since not all boards have the same
image size and/or flash bank mapping, they can't use the same script.