[U-Boot] powerpc/mpc85xx: Increase image size

[Scott Wood]

On Fri, 2013-10-11 at 11:29 -0700, York Sun wrote:
> Scott, et al.
> 
> I'd like to start the discussion to increase u-boot image size for some
> mpc85xx targets. As we all know the reset vector is at the very end and
> linking process start from the top. This gives us no good choice but to
> use fixed image size. While we have more and more features, the size
> increases inevitably. It's time to adjust the arbitrary size. We are now
> using 512KB. Shall we go with 768KB, or even 1MB?

768K would affect fewer existing partition maps (many of which leave 1M
for U-Boot and environment combined), but 1M might be better for new
boards.  And of course it would be nice if someone could spare some time
to try to slim things down (finer-grained compile-time config,
speed/size tradeoffs, etc).

> For the first step, I think we don't have to increase size for all
> targets. We can adjust those with CONFIG_SYS_TEXT_BASE=0xeff80000. Those
> are the most recent used. There are other targets which don't use NOR
> flash boot method. They should be considered as well.
> 
> It is per board configuration. But it may be better if we keep them
> consistent.

I don't think it's worth trying to keep them consistent.  Leave alone
old boards that are not pushing the limit, and where testing and user
education would be a hassle, and let newer boards where more features
are wanted not be constrained by the past.

-Scott