Why does the verification of hash value calculated on a file placed in tmp dir fail?

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Why does the verification of hash value calculated on a file placed in tmp dir fail?

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alex12
Contributor I

Hello,

We observe a phenomenon on a custom board that is equipped with an i.mx7d and 512MB lpddr2.

The verification of the hash value calculated on a file placed in tmp directory fails:
# dd if=/dev/urandom of=/tmp/testfile bs=1M count=50
50+0 records in
50+0 records out
#
#
# md5sum /tmp/testfile > /tmp/testmd5
# md5sum -c /tmp/testmd5
/tmp/testfile: FAILED
md5sum: WARNING: 1 of 1 computed checksums did NOT match
On the other hand a standard linux memory test succeeds on the same board:
# memtester 200 1
memtester version 4.3.0 (32-bit)
Copyright (C) 2001-2012 Charles Cazabon.
Licensed under the GNU General Public License version 2 (only).

pagesize is 4096
pagesizemask is 0xfffff000
want 200MB (209715200 bytes)
got  200MB (209715200 bytes), trying mlock ...locked.
Loop 1/1:
  Stuck Address       : ok
  Random Value        : ok
  Compare XOR         : ok
  Compare SUB         : ok
  Compare MUL         : ok
  Compare DIV         : ok
  Compare OR          : ok
  Compare AND         : ok
  Sequential Increment: ok
  Solid Bits          : ok
  Block Sequential    : ok
  Checkerboard        : ok
  Bit Spread          : ok
  Bit Flip            : ok
  Walking Ones        : ok
  Walking Zeroes      : ok
  8-bit Writes        : ok
  16-bit Writes       : ok

Done.

What could be the reason for this behavior?

Thanks and best regards

Alex

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alex12
Contributor I

Hi Yuri,

Thanks for your comments.

1. Yes, we ran the DDR Stress Test on corcerned boards overnight. The test passed.

2. We haven't tried to reproduce this issue on the i.MX7 SABRE board, but we ran the md5sum test on 100 custom boards. Three boards failed.

Could you please share your thoughts on my above statements.

Is there any specific verification strategy/test that targets the processor's cache memory?

Regards,

Alex

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Yuri
NXP TechSupport
NXP TechSupport

Hello,

 I've sent You message directly.

Regards,

Yuri.

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Yuri
NXP TechSupport
NXP TechSupport

Hello,

   Please look at my comments below.

1.

   Have You tried to check memory, using https://community.nxp.com/docs/DOC-105652?

2.

  Is the issue reproducible on the i.MX7 SABRE board?

Regards,

Yuri.

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