memtest help

[Bojan Prtvar <bojan.prtvar@rt-rk.com>]

Hello everyone,

I need to test all RAM cells on a linux ARM embedded system. My use case 
is very similar to the one described in [1] expect the fact I also have 
strong requirements on minimizing the boot time impact.
Instead of doing that from the bootloader, I decided to evaluate the 
linux memtest feature introduced with [2].

My questions are:

1)
Does the  early_memtest() as called in [3] really covers *all* RAM cells?

2)
As memtest happens very early in boot stage, what primitives I can use 
to measure duration of early_memtest()? Are there any known heuristics? 
I need to test ~2GB of RAM.
This is my major concern.

3)
It seems reasonable to expose the number of detected bad cells to user 
space. I was thinking about sysfs. Are the patches welcomed?

[1]
http://www.linuxforums.org/forum/newbie/173847-how-do-memory-ram-test-when-linux-running.html
[2]
http://lkml.iu.edu/hypermail/linux/kernel/1503.1/00566.html
[3]
http://lxr.free-electrons.com/source/arch/arm/mm/init.c#L291

Thanks,
Bojan

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