Dear Danny,
In message 52E15BAD.1020400@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