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

Wolfgang Denk
2010-05-27T19:53:18Z

Dear Scott Wood,

In message <20100527190340.GA5915@schlenkerla.am.freescale.net> you wrote:
>
> 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.

Typically we chose "maxsize" to b twice the actual possible maximum
to allow for real testing.

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

Such configurations are usually set up of from several differently
sized banks of memory, and get_ram_size() is always run per bank. So
as long as chip manufacturers continue to make RAM chips with
power-of-two sizes only, everything should be fine.

> [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.

Well, let's call this a bug in setting up the memory map for the
system ;-)

Best regards,

Wolfgang Denk

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