[U-Boot] T4QDS e6500 core and U-Boot 64-bit

[Wolfgang Denk]

Dear Danny,

In message <52E15BAD.1020400 at coloradoengineeringinc.com> you wrote:
> 
> > Yes - if you add support for 64 bit configurations in general, and
> > for powerpc64 in particular.
> I don't even have a sense for what would be involved here. How 
> fundamentally would the U-Boot code need to change?

It's probably heavy.  There is a ton of places where we assume we can
put an address in a "long" data type, etc.

> My reason for wanting to run 64-bit is that this system has 12 GB of 
> RAM. Will 32-bit U-Boot be able to access and test more than 4 GB of RAM?

No.  For the "access" part: usually this i not really needed.  U-Boot
is a boot loader, intended to load and start an OS.  for this, a 32
bit address space should be more than sufficient.  For the "test"
part, it is probably much easier to add a customized memory test (or
fix just the existing memory test such that it can be built for a 64
bit mode) and use this, then trying to run all of U-Boot in 64 bit
mode.

Best regards,

Wolfgang Denk

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