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Diffstat (limited to 'Documentation/admin-guide/ras.rst')
| -rw-r--r-- | Documentation/admin-guide/ras.rst | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/Documentation/admin-guide/ras.rst b/Documentation/admin-guide/ras.rst index 0310db624964..7b481b2a368e 100644 --- a/Documentation/admin-guide/ras.rst +++ b/Documentation/admin-guide/ras.rst @@ -156,11 +156,11 @@ the labels provided by the BIOS won't match the real ones. ECC memory ---------- -As mentioned on the previous section, ECC memory has extra bits to be -used for error correction. So, on 64 bit systems, a memory module -has 64 bits of *data width*, and 74 bits of *total width*. So, there are -8 bits extra bits to be used for the error detection and correction -mechanisms. Those extra bits are called *syndrome*\ [#f1]_\ [#f2]_. +As mentioned in the previous section, ECC memory has extra bits to be +used for error correction. In the above example, a memory module has +64 bits of *data width*, and 72 bits of *total width*. The extra 8 +bits which are used for the error detection and correction mechanisms +are referred to as the *syndrome*\ [#f1]_\ [#f2]_. So, when the cpu requests the memory controller to write a word with *data width*, the memory controller calculates the *syndrome* in real time, @@ -212,7 +212,7 @@ EDAC - Error Detection And Correction purposes. When the subsystem was pushed upstream for the first time, on - Kernel 2.6.16, for the first time, it was renamed to ``EDAC``. + Kernel 2.6.16, it was renamed to ``EDAC``. Purpose ------- @@ -351,15 +351,17 @@ controllers. The following example will assume 2 channels: +------------+-----------+-----------+ | | ``ch0`` | ``ch1`` | +============+===========+===========+ - | ``csrow0`` | DIMM_A0 | DIMM_B0 | - | | rank0 | rank0 | - +------------+ - | - | + | |**DIMM_A0**|**DIMM_B0**| + +------------+-----------+-----------+ + | ``csrow0`` | rank0 | rank0 | + +------------+-----------+-----------+ | ``csrow1`` | rank1 | rank1 | +------------+-----------+-----------+ - | ``csrow2`` | DIMM_A1 | DIMM_B1 | - | | rank0 | rank0 | - +------------+ - | - | - | ``csrow3`` | rank1 | rank1 | + | |**DIMM_A1**|**DIMM_B1**| + +------------+-----------+-----------+ + | ``csrow2`` | rank0 | rank0 | + +------------+-----------+-----------+ + | ``csrow3`` | rank1 | rank1 | +------------+-----------+-----------+ In the above example, there are 4 physical slots on the motherboard |