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authorLinus Torvalds <torvalds@linux-foundation.org>2019-11-25 18:07:36 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-11-25 18:07:36 -0800
commit9c91e6a5befb89d1494dd156dd4563f9e948a74f (patch)
tree8e3b4bf856d682c72b1b6c20f594a0763f044ddd /Documentation/admin-guide
parentMerge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm (diff)
parentEDAC/altera: Use the Altera System Manager driver (diff)
downloadlinux-dev-9c91e6a5befb89d1494dd156dd4563f9e948a74f.tar.xz
linux-dev-9c91e6a5befb89d1494dd156dd4563f9e948a74f.zip
Merge tag 'edac_for_5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras
Pull EDAC updates from Borislav Petkov: "A lot of changes this time around, details below. From the next cycle onwards, we'll switch the EDAC tree to topic branches (instead of a single edac-for-next branch) which should make the changes handling more flexible, hopefully. We'll see. Summary: - Rework error logging functions to accept a count of errors parameter (Hanna Hawa) - Part one of substantial EDAC core + ghes_edac driver cleanup (Robert Richter) - Print additional useful logging information in skx_* (Tony Luck) - Improve amd64_edac hw detection + cleanups (Yazen Ghannam) - Misc cleanups, fixes and code improvements" * tag 'edac_for_5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras: (35 commits) EDAC/altera: Use the Altera System Manager driver EDAC/altera: Cleanup the ECC Manager EDAC/altera: Use fast register IO for S10 IRQs EDAC/ghes: Do not warn when incrementing refcount on 0 EDAC/Documentation: Describe CPER module definition and DIMM ranks EDAC: Unify the mc_event tracepoint call EDAC/ghes: Remove intermediate buffer pvt->detail_location EDAC/ghes: Fix grain calculation EDAC/ghes: Use standard kernel macros for page calculations EDAC: Remove misleading comment in struct edac_raw_error_desc EDAC/mc: Reduce indentation level in edac_mc_handle_error() EDAC/mc: Remove needless zero string termination EDAC/mc: Do not BUG_ON() in edac_mc_alloc() EDAC: Introduce an mci_for_each_dimm() iterator EDAC: Remove EDAC_DIMM_OFF() macro EDAC: Replace EDAC_DIMM_PTR() macro with edac_get_dimm() function EDAC/amd64: Get rid of the ECC disabled long message EDAC/ghes: Fix locking and memory barrier issues EDAC/amd64: Check for memory before fully initializing an instance EDAC/amd64: Use cached data when checking for ECC ...
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/ras.rst31
1 files changed, 19 insertions, 12 deletions
diff --git a/Documentation/admin-guide/ras.rst b/Documentation/admin-guide/ras.rst
index 2b20f5f7380d..0310db624964 100644
--- a/Documentation/admin-guide/ras.rst
+++ b/Documentation/admin-guide/ras.rst
@@ -330,9 +330,12 @@ There can be multiple csrows and multiple channels.
.. [#f4] Nowadays, the term DIMM (Dual In-line Memory Module) is widely
used to refer to a memory module, although there are other memory
- packaging alternatives, like SO-DIMM, SIMM, etc. Along this document,
- and inside the EDAC system, the term "dimm" is used for all memory
- modules, even when they use a different kind of packaging.
+ packaging alternatives, like SO-DIMM, SIMM, etc. The UEFI
+ specification (Version 2.7) defines a memory module in the Common
+ Platform Error Record (CPER) section to be an SMBIOS Memory Device
+ (Type 17). Along this document, and inside the EDAC subsystem, the term
+ "dimm" is used for all memory modules, even when they use a
+ different kind of packaging.
Memory controllers allow for several csrows, with 8 csrows being a
typical value. Yet, the actual number of csrows depends on the layout of
@@ -349,12 +352,14 @@ controllers. The following example will assume 2 channels:
| | ``ch0`` | ``ch1`` |
+============+===========+===========+
| ``csrow0`` | DIMM_A0 | DIMM_B0 |
- +------------+ | |
- | ``csrow1`` | | |
+ | | rank0 | rank0 |
+ +------------+ - | - |
+ | ``csrow1`` | rank1 | rank1 |
+------------+-----------+-----------+
| ``csrow2`` | DIMM_A1 | DIMM_B1 |
- +------------+ | |
- | ``csrow3`` | | |
+ | | rank0 | rank0 |
+ +------------+ - | - |
+ | ``csrow3`` | rank1 | rank1 |
+------------+-----------+-----------+
In the above example, there are 4 physical slots on the motherboard
@@ -374,11 +379,13 @@ which the memory DIMM is placed. Thus, when 1 DIMM is placed in each
Channel, the csrows cross both DIMMs.
Memory DIMMs come single or dual "ranked". A rank is a populated csrow.
-Thus, 2 single ranked DIMMs, placed in slots DIMM_A0 and DIMM_B0 above
-will have just one csrow (csrow0). csrow1 will be empty. On the other
-hand, when 2 dual ranked DIMMs are similarly placed, then both csrow0
-and csrow1 will be populated. The pattern repeats itself for csrow2 and
-csrow3.
+In the example above 2 dual ranked DIMMs are similarly placed. Thus,
+both csrow0 and csrow1 are populated. On the other hand, when 2 single
+ranked DIMMs are placed in slots DIMM_A0 and DIMM_B0, then they will
+have just one csrow (csrow0) and csrow1 will be empty. The pattern
+repeats itself for csrow2 and csrow3. Also note that some memory
+controllers don't have any logic to identify the memory module, see
+``rankX`` directories below.
The representation of the above is reflected in the directory
tree in EDAC's sysfs interface. Starting in directory