[U-Boot] [RFC] ARM: U-boot and 2 GiB of ram with get_ram_size only being long

[Wolfgang Denk]

Dear Scott Wood,

In message <1382114601.7979.843.camel at snotra.buserror.net> you wrote:
>
> Did you see my other mail in this thread?  This patch is sort of OK for
> raising the get_ram_size() limit from 1 GiB to 2 GiB (with an increased
> risk of false positives from I/O), but it can't go beyond that on
> 32-bit.  A better approach would be to get the RAM size from the memory
> controller, which is what we do on many Freescale PPC boards.

This is NOT a better approach.  Reading the memory controller just
tells you what is supposed to be there, i. e. what you programmed into
the controller.  get_ram_size() shows you what is _actually_ there,
which may be a totally different thing, for example when different RAM
chips can be fit on the board, or when the working area of the RAM is
not the same as the actual chip size, for example due to hardware
errors (shorts or interruptions on the address lines, etc.).

get_ram_size() is a very efficient memory test that detects 95% or
more of all RAM related hardware issues.

Best regards,

Wolfgang Denk

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