[U-Boot] [PATCH] powerpc: add support for the Freescale P1022DS reference board

Scott Wood
2010-05-27T19:03:40Z

On Thu, May 27, 2010 at 01:25:38PM -0500, Timur Tabi wrote:
> Wolfgang Denk wrote:
>
> > Do you think this is an unreasonable request? A quick fix takes me
> > less than it takes to write this email (see following patch).
>
> Fixing get_ram_size() is not a quick fix. We would need to implement a
> temporary TLB mechanism for accessing memory above 2GB, and a machine check
> handler for handling memory access to non-existent RAM.

Passing the actual, known size of RAM (why guess when we know?) as "maxsize"
should eliminate the machine check problem[1] -- you'd just be using it as a
not particularly exhaustive memory tester. I don't see why it should be
mandatory.

It also doesn't handle non-power-of-two sized memory -- don't rely on the
value it returns.

-Scott

[1] It's worse than machine checks, what if some I/O device is mapped
directly after RAM? IIRC people have run into this sort of problem doing
this type of memory sizing on PCs.