[U-Boot] [RFC] arm926ejs: fix jump to RAM nand_boot

[Wolfgang Denk <wd@denx.de>]

Dear Albert ARIBAUD,

In message <4CCFDE45.3060306@free.fr> you wrote:
>
> These is a valid point that the SPL isn't necessarily rebuilt and 
> flashed every time u-boot itself is built and flashed, so whatever 
> constant the SPL would carry would only be valid for the u-boot that was 
> built alongside.

I have to admit that I was not aware that there are systems were SPL
and U-Boot itself are not bundled into a single image, but handled
separately. [I have to admit that I don;t like such a setup; it cries
for incompatibilities and other trouble.]

> Now a solution would be that the actual u-boot size be flashed along 
> with it, for instance as a literal defined as '.word _end - _start' 
> right after the vectors. The SPL could load a first NAND block, read the 
> literal, round it to a multiple of NAND blocks by default, and then read 
> this quantity.
> 
> That would remove the dependency at the cost of extra code in the SPL, 
> though, and not all boards might be able to afford it.

Indeed. Maybe be can combine several approaches:

- In case SPL and U-Boot are combined into a single image anyway, we
  can use a compile-time compution of the needed length, without
  additional code in the SPL.
- Where this is not prossible (i. e. SPL and U-Boot are separate), we
  can try and optionally provide the solution you suggest.
- Where memory is toot ight to allow for that code, the old style of a
  static #define will be used as a fallback.

Best regards,

Wolfgang Denk

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