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1 memtester is a utility for testing the memory subsystem in a computer to
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2 determine if it is faulty.
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3
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4 Usage is simple for the basic case. As root, run the resulting memtester binary
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5 with the following commandline:
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6
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7 memtester <memory> [runs]
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8
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9 where `<memory>` is the amount of memory to test, in megabytes by default. You
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10 can optionally include a suffix of B, K, M, or G (for bytes, kilobytes,
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11 megabytes, and gigabytes respectively).
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12
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13 `[runs]` is an optional limit to the number of runs through all tests.
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14
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15 An optional `-p physaddr` argument available to cause memtester to test memory
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16 starting at a specific physical memory address (by mmap(2)ing a device file
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17 representing physical memory (/dev/mem by default, but can be specified with the
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18 `-d device` option) starting at an offset of `physaddr`, which is given in hex).
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19
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20 Note: the memory specified will be overwritten during testing; you therefore
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21 *cannot* specify a region belonging to the kernel or other applications without
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22 causing the other process or entire system to crash). If you use this option, it
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23 is up to you to ensure the specified memory is safe to overwrite. That makes
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24 this option mostly of use for testing memory-mapped I/O devices and similar.
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25 Thanks to Allon Stern for the idea behind this feature. For example, if you want
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26 to test a bank of RAM or device which is 64kbytes in size and starts at physical
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27 address 0x0C0000 through the normal /dev/mem, you would run memtester as
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28 follows:
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29
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30 memtester -p 0x0c0000 64k [runs]
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31
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32 If instead that device presented its memory as /dev/foodev at offset 0, you
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33 would run memtester instead as follows:
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34
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35 memtester -p 0 -d /dev/foodev 64k [runs]
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36
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37 Note that the `-d` option can only be specified in combination with `-p`.
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38
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39 memtester must run as user root so that it can lock its pages into memory. If
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40 memtester fails to lock its pages, it will issue a warning and continue
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41 regardless. Testing without the memory being locked is generally very slow and
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42 not particularly accurate, as you'll end up testing the same memory over and
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43 over as the system swaps the larger region.
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