On Thu, 2014-01-23 at 11:13 -0700, Danny Gale wrote:
Hi Wolfgang,
Thanks for your reply. My responses are inline below.
On 1/22/2014 2:06 AM, Wolfgang Denk wrote:
Dear Danny Gale,
In message 52DF18B3.1080904@coloradoengineeringinc.com you wrote:
The T4240 on the T4QDS board is a PPC e6500 core (64 bit), but it is configured in U-Boot as an e500 core, which is 32 bit. Why is this?
Becuase it simply works :-)
Can it be updated to e6500?
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?
The common U-Boot code should be more or less OK -- the armv8 target runs as 64-bit, and sandbox can as well. The PPC code is another matter, though. You'd need to hack up or replace a bunch of asm code at the least.
This leads directly into another question: can U-Boot be compiled and run 64-bit? So far, I have been unable to make it work with a 64-bit compiler. I'm running into these errors:
Not out of the box.
What is your actual reason for wanting to run a 64 bit boot loader?
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?
32-bit U-Boot can detect (or otherwise know about) and tell the OS about large amounts of RAM, but it can only directly access 2 GiB.
-Scott