[U-Boot-Users] Re: Moving u-boot location in ram to do full mem-test?

Martin Egholm Nielsen martin at egholm-nielsen.dk
Wed Nov 23 10:46:25 CET 2005

Hi Wolfgang,

>>But couldn't there be an error for a specific address segment - say 
>>"0x3ff0000"-"0x3ff00ff", which contains u-boot data never being used in 
>>u-boot, and not possible to test with mtest?
> In theory there could be such a problem. But 99% of  all  RAM  memory
> errors fall into different patterns - at least from what I've seen.
I have a specific board acting strange, so I was for starters suspecting 
memory. But I will solder in a new memory chip to see if that indeed was 
the problem...

>>>Linux  with  root  file  system  mounted over NFS and compile a Linux
>>>kernel on the target. No smiley here, I really mean it.
>>Yes, but that would take days, if at all possible, on my 133 Mhz 
>>PPC405EP with 32 megs.
> No. It takes 2...3 hours on a MPC860 with 50 MHz,  so  you  might  be
> done with approx. one hour or so (assuming a 2.4 kernel tree). And of
> course  you  can  stop any time you like - as long as the system does
> not crash you are fine.

>>Then, I would rather have a "similar" memory exhausting test-application 
>>for Linux...
> It's not just "memory exhaustion". It's the  combination  of  context
> switches,  code fetching, DMA going on all simultaneously. I have yet
> to find any other test code that  produces  back-to-back  burst  mode
> accesses  in  such a density. It's really difficult to come up with a
> similar strong memory test.
I see your point...

> And bythe way - if you're testing your memory you *want* to have this
> test  running  for  a  long  time,  probably   changing   operational
> parameters like temperature, voltages, ... while runnign the test. Or
> injecting EM "noise" if you're testing for EMC...
Sure - but this is really too extensive for the individual board.
We're doing EMC test for a couple of units to the see the general 
picture, but all units will run a 24h burnin test at 50 degrees Celcius...

Ok, for now I'll abandon the idea of expanding the mtest area, and 
change the chip on the board that is causing me headaches...


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