forked from ~ljy/RK356X_SDK_RELEASE
blame | history | patch | commit | commitdiff
hc
2024-10-09 244b2c5ca8b14627e4a17755e5922221e121c771 
 kernel/Documentation/admin-guide/ras.rst
....@@ -54,7 +54,7 @@
5454 Types of errors
5555 ---------------
5656 
57
-Most mechanisms used on modern systems use use technologies like Hamming
57
+Most mechanisms used on modern systems use technologies like Hamming
5858 Codes that allow error correction when the number of errors on a bit packet
5959 is below a threshold. If the number of errors is above, those mechanisms
6060 can indicate with a high degree of confidence that an error happened, but
....@@ -156,11 +156,11 @@
156156 ECC memory
157157 ----------
158158 
159
-As mentioned on the previous section, ECC memory has extra bits to be
160
-used for error correction. So, on 64 bit systems, a memory module
161
-has 64 bits of *data width*, and 74 bits of *total width*. So, there are
162
-8 bits extra bits to be used for the error detection and correction
163
-mechanisms. Those extra bits are called *syndrome*\ [#f1]_\ [#f2]_.
159
+As mentioned in the previous section, ECC memory has extra bits to be
160
+used for error correction. In the above example, a memory module has
161
+64 bits of *data width*, and 72 bits of *total width*.  The extra 8
162
+bits which are used for the error detection and correction mechanisms
163
+are referred to as the *syndrome*\ [#f1]_\ [#f2]_.
164164 
165165 So, when the cpu requests the memory controller to write a word with
166166 *data width*, the memory controller calculates the *syndrome* in real time,
....@@ -199,7 +199,7 @@
199199   mode).
200200 
201201 .. [#f3] For more details about the Machine Check Architecture (MCA),
202
-  please read Documentation/x86/x86_64/machinecheck at the Kernel tree.
202
+  please read Documentation/x86/x86_64/machinecheck.rst at the Kernel tree.
203203 
204204 EDAC - Error Detection And Correction
205205 *************************************
....@@ -212,7 +212,7 @@
212212    purposes.
213213 
214214    When the subsystem was pushed upstream for the first time, on
215
-   Kernel 2.6.16, for the first time, it was renamed to ``EDAC``.
215
+   Kernel 2.6.16, it was renamed to ``EDAC``.
216216 
217217 Purpose
218218 -------
....@@ -330,9 +330,12 @@
330330 
331331 .. [#f4] Nowadays, the term DIMM (Dual In-line Memory Module) is widely
332332   used to refer to a memory module, although there are other memory
333
-  packaging alternatives, like SO-DIMM, SIMM, etc. Along this document,
334
-  and inside the EDAC system, the term "dimm" is used for all memory
335
-  modules, even when they use a different kind of packaging.
333
+  packaging alternatives, like SO-DIMM, SIMM, etc. The UEFI
334
+  specification (Version 2.7) defines a memory module in the Common
335
+  Platform Error Record (CPER) section to be an SMBIOS Memory Device
336
+  (Type 17). Along this document, and inside the EDAC subsystem, the term
337
+  "dimm" is used for all memory modules, even when they use a
338
+  different kind of packaging.
336339 
337340 Memory controllers allow for several csrows, with 8 csrows being a
338341 typical value. Yet, the actual number of csrows depends on the layout of
....@@ -348,13 +351,17 @@
348351 	+------------+-----------+-----------+
349352 	|            |  ``ch0``  |  ``ch1``  |
350353 	+============+===========+===========+
351
-	| ``csrow0`` |  DIMM_A0  |  DIMM_B0  |
352
-	+------------+           |           |
353
-	| ``csrow1`` |           |           |
354
+	|            |**DIMM_A0**|**DIMM_B0**|
354355 	+------------+-----------+-----------+
355
-	| ``csrow2`` |  DIMM_A1  | DIMM_B1   |
356
-	+------------+           |           |
357
-	| ``csrow3`` |           |           |
356
+	| ``csrow0`` |   rank0   |   rank0   |
357
+	+------------+-----------+-----------+
358
+	| ``csrow1`` |   rank1   |   rank1   |
359
+	+------------+-----------+-----------+
360
+	|            |**DIMM_A1**|**DIMM_B1**|
361
+	+------------+-----------+-----------+
362
+	| ``csrow2`` |    rank0  |  rank0    |
363
+	+------------+-----------+-----------+
364
+	| ``csrow3`` |    rank1  |  rank1    |
358365 	+------------+-----------+-----------+
359366 
360367 In the above example, there are 4 physical slots on the motherboard
....@@ -374,11 +381,13 @@
374381 Channel, the csrows cross both DIMMs.
375382 
376383 Memory DIMMs come single or dual "ranked". A rank is a populated csrow.
377
-Thus, 2 single ranked DIMMs, placed in slots DIMM_A0 and DIMM_B0 above
378
-will have just one csrow (csrow0). csrow1 will be empty. On the other
379
-hand, when 2 dual ranked DIMMs are similarly placed, then both csrow0
380
-and csrow1 will be populated. The pattern repeats itself for csrow2 and
381
-csrow3.
384
+In the example above 2 dual ranked DIMMs are similarly placed. Thus,
385
+both csrow0 and csrow1 are populated. On the other hand, when 2 single
386
+ranked DIMMs are placed in slots DIMM_A0 and DIMM_B0, then they will
387
+have just one csrow (csrow0) and csrow1 will be empty. The pattern
388
+repeats itself for csrow2 and csrow3. Also note that some memory
389
+controllers don't have any logic to identify the memory module, see
390
+``rankX`` directories below.
382391 
383392 The representation of the above is reflected in the directory
384393 tree in EDAC's sysfs interface. Starting in directory