On Friday, July 4, 2003, at 11:03  AM, Steve Woodford wrote:

> Making use of the first chunk of SDRAM on a RedBoot system will require
> some more work, however. Perhaps the easiest way would be to make the
> kernel self-relocating. Note that there may be issues associated with
> trashing the RedBoot area of SDRAM, with respect to rebooting, for
> example.
>
> Of course, this would all be moot if RedBoot reserved the top 2MB of 
> SDRAM
> instead. ;-)

It's not really RedBoot that's an issue.  Here's what the situation 
is...

The kernel needs to be loaded "somewhere out of the way" of RedBoot.  
Fine, we do that.  There is also the "gzboot" loader which may also 
run, which also needs to be out of the way of the kernel.

To make this easy on myself, I simply used the following rule:

	1. gzboot loads at RAM+1MB.

	2. kernel loads at RAM+2MB.

The kernel actually does reclaim a bunch of that memory -- it uses it 
for initial page tables, stacks, etc.  It could probably use more of 
it, but it's not like it's all going to waste.

         -- Jason R. Thorpe <thorpej@wasabisystems.com>