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diff --git a/Documentation/edac.txt b/Documentation/edac.txt index 79c5332..0b875e8 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 +719,153 @@ 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. This is + associated with a physical CPU 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 sequencially + maps channel/dimm into different csrows. + + For example, suposing the following layout: + Ch0 phy rd0, wr0 (0x063f4031): 2 ranks, UDIMMs + dimm 0 1024 Mb offset: 0, bank: 8, rank: 1, row: 0x4000, col: 0x400 + dimm 1 1024 Mb offset: 4, bank: 8, rank: 1, row: 0x4000, col: 0x400 + Ch1 phy rd1, wr1 (0x063f4031): 2 ranks, UDIMMs + dimm 0 1024 Mb offset: 0, bank: 8, rank: 1, row: 0x4000, col: 0x400 + Ch2 phy rd3, wr3 (0x063f4031): 2 ranks, UDIMMs + dimm 0 1024 Mb offset: 0, bank: 8, rank: 1, row: 0x4000, col: 0x400 + The driver will map it as: + csrow0: channel 0, dimm0 + csrow1: channel 0, dimm1 + csrow2: channel 1, dimm0 + csrow3: channel 2, dimm0 + +exports one + DIMM per csrow. + + Each QPI is exported as a different memory controller. + +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/mc?/: + + 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 2 >/sys/devices/system/edac/mc/mc0/inject_addrmatch/dimm + echo 1 >/sys/devices/system/edac/mc/mc0/inject_addrmatch/rank + + To return to the default behaviour of matching any, you can do: + echo any >/sys/devices/system/edac/mc/mc0/inject_addrmatch/dimm + echo any >/sys/devices/system/edac/mc/mc0/inject_addrmatch/rank + + 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_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 2 >/sys/devices/system/edac/mc/mc0/inject_addrmatch/channel + 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 1 >/sys/devices/system/edac/mc/mc0/inject_enable + dd if=/dev/mem of=/dev/null seek=16k bs=4k count=1 >& /dev/null + + For socket 1, it is needed to replace "mc0" by "mc1" at the above + commands. + + 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. The driver uses those + registers to report Corrected Errors on devices with Registered Dimms. + + However, those counters don't work with Unregistered Dimms. As the chipset + offers some counters that also work with UDIMMS (but with a worse level of + granularity than the default ones), the driver exposes those registers for + UDIMM memories. + + They can be read by looking at the contents of all_channel_counts/ + + $ for i in /sys/devices/system/edac/mc/mc0/all_channel_counts/*; do echo $i; cat $i; done + /sys/devices/system/edac/mc/mc0/all_channel_counts/udimm0 + 0 + /sys/devices/system/edac/mc/mc0/all_channel_counts/udimm1 + 0 + /sys/devices/system/edac/mc/mc0/all_channel_counts/udimm2 + 0 + + What happens here is that errors on different csrows, but at the same + dimm number will increment the same counter. + So, in this memory mapping: + csrow0: channel 0, dimm0 + csrow1: channel 0, dimm1 + csrow2: channel 1, dimm0 + csrow3: channel 2, dimm0 + The hardware will increment udimm0 for an error at the first dimm at either + csrow0, csrow2 or csrow3; + The hardware will increment udimm1 for an error at the second dimm at either + csrow0, csrow2 or csrow3; + The hardware will increment udimm2 for an error at the third dimm at either + csrow0, csrow2 or csrow3; + +4) Standard error counters + + The standard error counters are generated when an mcelog error is received + by the driver. Since, with udimm, this is counted by software, it is + possible that some errors could be lost. With rdimm's, they displays the + contents of the registers |
