[maemo-developers] [maemo-developers] defective memory? (was: problem with dspmp3sink)

[From: Olivier ROLAND]

Siarhei Siamashka a écrit :
> On Sunday 10 September 2006 11:36, Olivier ROLAND wrote:
>
>   
>> Your test work fine on my device.
>> I see that you run it from /media/mmc1so I guess you format your memory
>> card with ext2.
>> Mine still vfat so I can't. If you got same error when running from
>> internal memory then your device is broken.
>>     
>
> Thanks a lot for finding time and running the test.
>
> Today in the morning I could not reproduce this bug. The device battery just
> was recharged during night. As nothing else was changed (I checked uptime to
> be sure that it did not reboot or something), I see three possible
> explanations (may be wrong, I'm not hardware expert):
> * page with the faulty memory bit was allocated to some other process
> * cpu or memory chip was just overheated because of heavy use and the
> bug disappeared as the temperature got back to normal
> * maybe the bug is somewhat related to low battery charge level, maybe the
> battery was unable to provide enough voltage or something for reliable
> operation
>
> I did some search and found this utility for testing memory on non-x86
> hardware: http://pyropus.ca/software/memtester/
> For those who are lazy to compile it, the binary is here:
> http://ufo2000.xcomufo.com/files/memtester.gz
>
> After playing with the device for some time, I got the same problem with lzma
> program this evening. And memtester also confirms that the memory 
> is really defective :(
>
> # ./memtester 20
> memtester version 4.0.5 (32-bit)
> Copyright (C) 2005 Charles Cazabon.
> Licensed under the GNU General Public License version 2 (only).
>
> pagesize is 4096
> pagesizemask is 0xfffff000
> want 20MB (20971520 bytes)
> got  20MB (20971520 bytes), trying mlock ...locked.
> Loop 1:
>   Stuck Address       : testing   0FAILURE: possible bad address line at 
> offset 0x0037e9a5.
> Skipping to next test...
>   Random Value        : FAILURE: 0xdeb98374 != 0xdeb90000 at offset 
> 0x000fe9a4.
> FAILURE: 0xd04629fc != 0xd046aa88 at offset 0x000fe9a4.
>   Compare XOR         : FAILURE: 0x50467c54 != 0x50460000 at offset 
> 0x000fe9a4.
>   Compare SUB         : FAILURE: 0xb069e1c0 != 0xdc200000 at offset 
> 0x000fe9a4.
> ...
>
> By the way, I have seen some reports about random device reboots, maybe 
> these people also suffer from defective memory problem. So maybe it is a 
> good idea for everyone to test their memory. Though use it at your own risk, I
> can't be sure that this test program is working correctly and always provides
> valid results (I only found it today).
>
> Well, as now the problem is identified, it is time to think how to solve it.
>
> The first task is making a proper memory testing utility. As memtester needs
> to allocate memory for testing and lots of memory is already taken by IT OS 
> software and libraries, we can only test a small part of memory (only ~1/3 in
> the test above). Maybe it is possible to patch kernel (or it already provides
> such functionality) to allocate any physical memory page for us (relocating
> its data to some other place if it is already occupied by some other process).
> If it is possible, we would be able to check all the physical memory except
> for probably the part occupied by the kernel itself.
>
> The next task would be to make some way to use BadRAM kernel patch on 
> Nokia 770: http://rick.vanrein.org/linux/badram/
> Preferably physical addresses of the defective parts of memory should be
> stored somewhere so that they survive reflashing (r&d mode and other flags 
> are stored in such a way, right?). If BadRAM patch becomes a part of 
> standard Nokia 770 kernel, it can help to make use of the memory chips that
> otherwise would have to be replaced. I wonder how much does Nokia 770 
> memory chip cost?
>
> By the way, maybe Nokia already has some utility for hardware diagnistics 
> and it could become available for download? There would be no need to 
> reinvent the wheel in this case.
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>   
Hum ... very interesting memtester give non reproductible result on my 
device.
and now lzma test failed also ...
Battery is low. We definitively need to investigate this a little more.
The good news is that your device is probably not broken. (or mine is 
also ;-) )
All this should definitively interest Nokia people ...


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