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diff --git a/Documentation/edac.txt b/Documentation/edac.txt index 79c53322376..8bc320467c6 100644 --- a/Documentation/edac.txt +++ b/Documentation/edac.txt @@ -6,6 +6,8 @@ Written by Doug Thompson <dougthompson@xmission.com> 7 Dec 2005 17 Jul 2007 Updated +(c) Mauro Carvalho Chehab <mchehab@redhat.com> +05 Aug 2009 Nehalem interface EDAC is maintained and written by: @@ -717,3 +719,111 @@ unique drivers for their hardware systems. The 'test_device_edac' sample driver is located at the bluesmoke.sourceforge.net project site for EDAC. +======================================================================= +NEHALEM USAGE OF EDAC APIs + +This chapter documents some EXPERIMENTAL mappings for EDAC API to handle +Nehalem EDAC driver. They will likely be changed on future versions +of the driver. + +Due to the way Nehalem exports Memory Controller data, some adjustments +were done at i7core_edac driver. This chapter will cover those differences + +1) On Nehalem, there are one Memory Controller per Quick Patch Interconnect + (QPI). At the driver, the term "socket" means one QPI. It should also be + associated with the CPU physical socket. + + Each MC have 3 physical read channels, 3 physical write channels and + 3 logic channels. The driver currenty sees it as just 3 channels. + Each channel can have up to 3 DIMMs. + + The minimum known unity is DIMMs. There are no information about csrows. + As EDAC API maps the minimum unity is csrows, the driver exports one + DIMM per csrow. + + Currently, it also exports the several memory controllers as just one. This + limit will be removed on future versions of the driver. + +2) Nehalem MC has the hability to generate errors. The driver implements this + functionality via some error injection nodes: + + For injecting a memory error, there are some sysfs nodes, under + /sys/devices/system/edac/mc/mc0/: + + inject_addrmatch: + Controls the error injection mask register. It is possible to specify + several characteristics of the address to match an error code: + dimm = the affected dimm. Numbers are relative to a channel; + rank = the memory rank; + channel = the channel that will generate an error; + bank = the affected bank; + page = the page address; + column (or col) = the address column. + each of the above values can be set to "any" to match any valid value. + + At driver init, all values are set to any. + + For example, to generate an error at rank 1 of dimm 2, for any channel, + any bank, any page, any column: + echo "dimm:2 rank:1" >/sys/devices/system/edac/mc/mc0/inject_addrmatch + + To return to the default behaviour of matching any, you can do: + echo "dimm:any rank:any" >/sys/devices/system/edac/mc/mc0/inject_addrmatch + + inject_eccmask: + specifies what bits will have troubles, + + inject_section: + specifies what ECC cache section will get the error: + 3 for both + 2 for the highest + 1 for the lowest + + inject_socket: + specifies what QPI (or processor socket) will generate the error. + on Xeon 35xx, it should be 0. + on Xeon 55xx, it should be 0 or 1. + + inject_type: + specifies the type of error, being a combination of the following bits: + bit 0 - repeat + bit 1 - ecc + bit 2 - parity + + inject_enable starts the error generation when something different + than 0 is written. + + All inject vars can be read. root permission is needed for write. + + Datasheet states that the error will only be generated after a write on an + address that matches inject_addrmatch. It seems, however, that reading will + also produce an error. + + For example, the following code will generate an error for any write access + at socket 0, on any DIMM/address on channel 2: + + echo "channel:2" > /sys/devices/system/edac/mc/mc0/inject_addrmatch + echo 2 >/sys/devices/system/edac/mc/mc0/inject_type + echo 64 >/sys/devices/system/edac/mc/mc0/inject_eccmask + echo 3 >/sys/devices/system/edac/mc/mc0/inject_section + echo 0 >/sys/devices/system/edac/mc/mc0/inject_socket + echo 1 >/sys/devices/system/edac/mc/mc0/inject_enable + dd if=/dev/mem of=/dev/null seek=16k bs=4k count=1 >& /dev/null + + The generated error message will look like: + + EDAC MC0: UE row 0, channel-a= 0 channel-b= 0 labels "-": NON_FATAL (addr = 0x0075b980, socket=0, Dimm=0, Channel=2, syndrome=0x00000040, count=1, Err=8c0000400001009f:4000080482 (read error: read ECC error)) + +3) Nehalem specific Corrected Error memory counters + + Nehalem have some registers to count memory errors, reporting it on a + way that it is different from what EDAC API allows. Due to that, a + separate sysfs note were created to handle such counters. + + They can be read by looking at the contents of "corrected_error_counts" + counter: + + $ cat /sys/devices/system/edac/mc/mc0/corrected_error_counts + dimm0: 15866 + dimm1: 0 + dimm2: 27285 |