[U-Boot] [PATCH 2/4] Use LINK_OFF to access global data

[Mike Frysinger]

On Sunday 03 January 2010 14:51:53 Wolfgang Denk wrote:
> If I try to see trends in the development of U-Boot I notice a
> growing number of systems that boot from NAND flash, DataFlash or
> that come with on-chip ROM code to load images from SDCard and other
> storage media. Such systems cannot make real benefit from the
> original design of U-Boot, as here U-Boot is inherently a
> second-stage boot loader which gets loaded by some other means. Even
> for NAND booting systems where we have the NAND boot code included
> within the U-Boot source tree we often cannot share much of the code
> between the primary and the secondary loader stages as there are
> usually tight restrictions on the maximum size for the primary loader
> image. Here a sharper separation of "primary" and "secondary" boot
> code within U-Boot would be benefical.
> 
> I feel (but this is really just a feeling, and I definitely would like
> to hear what others think about this!) your PIC changes would be (or
> have been) useful for the former usage mode, but they come at a pretty
> heavy cost as they are really invasive to the code.  For the second
> usage mode they are not usable, or at least not useful.  This makes me
> wonder if we really should continue to work in this direction.

the Blackfin processors are going the direction of an on-chip ROM handles 
loading from some storage (nor/nand/spi/usb/uart/sd/whatever) into RAM.  there 
really isnt any usage model of executing in NOR for some time before running 
out of RAM.  so generally, all this additional support is seen largely as 
overhead on Blackfin parts since there isnt any need/desire for them.
-mike
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