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diff --git a/Documentation/edac.txt b/Documentation/edac.txt deleted file mode 100644 index f89cfd85ae13..000000000000 --- a/Documentation/edac.txt +++ /dev/null @@ -1,812 +0,0 @@ -EDAC - Error Detection And Correction -===================================== - -"bluesmoke" was the name for this device driver when it -was "out-of-tree" and maintained at sourceforge.net - -bluesmoke.sourceforge.net. That site is mostly archaic now and can be -used only for historical purposes. - -When the subsystem was pushed into 2.6.16 for the first time, it was -renamed to 'EDAC'. - -PURPOSE -------- - -The 'edac' kernel module's goal is to detect and report hardware errors -that occur within the computer system running under linux. - -MEMORY ------- - -Memory Correctable Errors (CE) and Uncorrectable Errors (UE) are the -primary errors being harvested. These types of errors are harvested by -the 'edac_mc' device. - -Detecting CE events, then harvesting those events and reporting them, -*can* but must not necessarily be a predictor of future UE events. With -CE events only, the system can and will continue to operate as no data -has been damaged yet. - -However, preventive maintenance and proactive part replacement of memory -DIMMs exhibiting CEs can reduce the likelihood of the dreaded UE events -and system panics. - -OTHER HARDWARE ELEMENTS ------------------------ - -A new feature for EDAC, the edac_device class of device, was added in -the 2.6.23 version of the kernel. - -This new device type allows for non-memory type of ECC hardware detectors -to have their states harvested and presented to userspace via the sysfs -interface. - -Some architectures have ECC detectors for L1, L2 and L3 caches, -along with DMA engines, fabric switches, main data path switches, -interconnections, and various other hardware data paths. If the hardware -reports it, then a edac_device device probably can be constructed to -harvest and present that to userspace. - - -PCI BUS SCANNING ----------------- - -In addition, PCI devices are scanned for PCI Bus Parity and SERR Errors -in order to determine if errors are occurring during data transfers. - -The presence of PCI Parity errors must be examined with a grain of salt. -There are several add-in adapters that do *not* follow the PCI specification -with regards to Parity generation and reporting. The specification says -the vendor should tie the parity status bits to 0 if they do not intend -to generate parity. Some vendors do not do this, and thus the parity bit -can "float" giving false positives. - -There is a PCI device attribute located in sysfs that is checked by -the EDAC PCI scanning code. If that attribute is set, PCI parity/error -scanning is skipped for that device. The attribute is: - - broken_parity_status - -and is located in /sys/devices/pci<XXX>/0000:XX:YY.Z directories for -PCI devices. - - -VERSIONING ----------- - -EDAC is composed of a "core" module (edac_core.ko) and several Memory -Controller (MC) driver modules. On a given system, the CORE is loaded -and one MC driver will be loaded. Both the CORE and the MC driver (or -edac_device driver) have individual versions that reflect current -release level of their respective modules. - -Thus, to "report" on what version a system is running, one must report -both the CORE's and the MC driver's versions. - - -LOADING -------- - -If 'edac' was statically linked with the kernel then no loading -is necessary. If 'edac' was built as modules then simply modprobe -the 'edac' pieces that you need. You should be able to modprobe -hardware-specific modules and have the dependencies load the necessary -core modules. - -Example: - -$> modprobe amd76x_edac - -loads both the amd76x_edac.ko memory controller module and the edac_mc.ko -core module. - - -SYSFS INTERFACE ---------------- - -EDAC presents a 'sysfs' interface for control and reporting purposes. It -lives in the /sys/devices/system/edac directory. - -Within this directory there currently reside 2 components: - - mc memory controller(s) system - pci PCI control and status system - - - -Memory Controller (mc) Model ----------------------------- - -Each 'mc' device controls a set of DIMM memory modules. These modules -are laid out in a Chip-Select Row (csrowX) and Channel table (chX). -There can be multiple csrows and multiple channels. - -Memory controllers allow for several csrows, with 8 csrows being a -typical value. Yet, the actual number of csrows depends on the layout of -a given motherboard, memory controller and DIMM characteristics. - -Dual channels allows for 128 bit data transfers to/from the CPU from/to -memory. Some newer chipsets allow for more than 2 channels, like Fully -Buffered DIMMs (FB-DIMMs). The following example will assume 2 channels: - - - Channel 0 Channel 1 - =================================== - csrow0 | DIMM_A0 | DIMM_B0 | - csrow1 | DIMM_A0 | DIMM_B0 | - =================================== - - =================================== - csrow2 | DIMM_A1 | DIMM_B1 | - csrow3 | DIMM_A1 | DIMM_B1 | - =================================== - -In the above example table there are 4 physical slots on the motherboard -for memory DIMMs: - - DIMM_A0 - DIMM_B0 - DIMM_A1 - DIMM_B1 - -Labels for these slots are usually silk-screened on the motherboard. -Slots labeled 'A' are channel 0 in this example. Slots labeled 'B' are -channel 1. Notice that there are two csrows possible on a physical DIMM. -These csrows are allocated their csrow assignment based on the slot into -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 1 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. - -The representation of the above is reflected in the directory -tree in EDAC's sysfs interface. Starting in directory -/sys/devices/system/edac/mc each memory controller will be represented -by its own 'mcX' directory, where 'X' is the index of the MC. - - - ..../edac/mc/ - | - |->mc0 - |->mc1 - |->mc2 - .... - -Under each 'mcX' directory each 'csrowX' is again represented by a -'csrowX', where 'X' is the csrow index: - - - .../mc/mc0/ - | - |->csrow0 - |->csrow2 - |->csrow3 - .... - -Notice that there is no csrow1, which indicates that csrow0 is composed -of a single ranked DIMMs. This should also apply in both Channels, in -order to have dual-channel mode be operational. Since both csrow2 and -csrow3 are populated, this indicates a dual ranked set of DIMMs for -channels 0 and 1. - - -Within each of the 'mcX' and 'csrowX' directories are several EDAC -control and attribute files. - - -'mcX' directories ------------------ - -In 'mcX' directories are EDAC control and attribute files for -this 'X' instance of the memory controllers. - -For a description of the sysfs API, please see: - Documentation/ABI/testing/sysfs-devices-edac - - - -'csrowX' directories --------------------- - -When CONFIG_EDAC_LEGACY_SYSFS is enabled, sysfs will contain the csrowX -directories. As this API doesn't work properly for Rambus, FB-DIMMs and -modern Intel Memory Controllers, this is being deprecated in favor of -dimmX directories. - -In the 'csrowX' directories are EDAC control and attribute files for -this 'X' instance of csrow: - - -Total Uncorrectable Errors count attribute file: - - 'ue_count' - - This attribute file displays the total count of uncorrectable - errors that have occurred on this csrow. If panic_on_ue is set - this counter will not have a chance to increment, since EDAC - will panic the system. - - -Total Correctable Errors count attribute file: - - 'ce_count' - - This attribute file displays the total count of correctable - errors that have occurred on this csrow. This count is very - important to examine. CEs provide early indications that a - DIMM is beginning to fail. This count field should be - monitored for non-zero values and report such information - to the system administrator. - - -Total memory managed by this csrow attribute file: - - 'size_mb' - - This attribute file displays, in count of megabytes, the memory - that this csrow contains. - - -Memory Type attribute file: - - 'mem_type' - - This attribute file will display what type of memory is currently - on this csrow. Normally, either buffered or unbuffered memory. - Examples: - Registered-DDR - Unbuffered-DDR - - -EDAC Mode of operation attribute file: - - 'edac_mode' - - This attribute file will display what type of Error detection - and correction is being utilized. - - -Device type attribute file: - - 'dev_type' - - This attribute file will display what type of DRAM device is - being utilized on this DIMM. - Examples: - x1 - x2 - x4 - x8 - - -Channel 0 CE Count attribute file: - - 'ch0_ce_count' - - This attribute file will display the count of CEs on this - DIMM located in channel 0. - - -Channel 0 UE Count attribute file: - - 'ch0_ue_count' - - This attribute file will display the count of UEs on this - DIMM located in channel 0. - - -Channel 0 DIMM Label control file: - - 'ch0_dimm_label' - - This control file allows this DIMM to have a label assigned - to it. With this label in the module, when errors occur - the output can provide the DIMM label in the system log. - This becomes vital for panic events to isolate the - cause of the UE event. - - DIMM Labels must be assigned after booting, with information - that correctly identifies the physical slot with its - silk screen label. This information is currently very - motherboard specific and determination of this information - must occur in userland at this time. - - -Channel 1 CE Count attribute file: - - 'ch1_ce_count' - - This attribute file will display the count of CEs on this - DIMM located in channel 1. - - -Channel 1 UE Count attribute file: - - 'ch1_ue_count' - - This attribute file will display the count of UEs on this - DIMM located in channel 0. - - -Channel 1 DIMM Label control file: - - 'ch1_dimm_label' - - This control file allows this DIMM to have a label assigned - to it. With this label in the module, when errors occur - the output can provide the DIMM label in the system log. - This becomes vital for panic events to isolate the - cause of the UE event. - - DIMM Labels must be assigned after booting, with information - that correctly identifies the physical slot with its - silk screen label. This information is currently very - motherboard specific and determination of this information - must occur in userland at this time. - - - -SYSTEM LOGGING --------------- - -If logging for UEs and CEs is enabled, then system logs will contain -information indicating that errors have been detected: - -EDAC MC0: CE page 0x283, offset 0xce0, grain 8, syndrome 0x6ec3, row 0, -channel 1 "DIMM_B1": amd76x_edac - -EDAC MC0: CE page 0x1e5, offset 0xfb0, grain 8, syndrome 0xb741, row 0, -channel 1 "DIMM_B1": amd76x_edac - - -The structure of the message is: - the memory controller (MC0) - Error type (CE) - memory page (0x283) - offset in the page (0xce0) - the byte granularity (grain 8) - or resolution of the error - the error syndrome (0xb741) - memory row (row 0) - memory channel (channel 1) - DIMM label, if set prior (DIMM B1 - and then an optional, driver-specific message that may - have additional information. - -Both UEs and CEs with no info will lack all but memory controller, error -type, a notice of "no info" and then an optional, driver-specific error -message. - - -PCI Bus Parity Detection ------------------------- - -On Header Type 00 devices, the primary status is looked at for any -parity error regardless of whether parity is enabled on the device or -not. (The spec indicates parity is generated in some cases). On Header -Type 01 bridges, the secondary status register is also looked at to see -if parity occurred on the bus on the other side of the bridge. - - -SYSFS CONFIGURATION -------------------- - -Under /sys/devices/system/edac/pci are control and attribute files as follows: - - -Enable/Disable PCI Parity checking control file: - - 'check_pci_parity' - - - This control file enables or disables the PCI Bus Parity scanning - operation. Writing a 1 to this file enables the scanning. Writing - a 0 to this file disables the scanning. - - Enable: - echo "1" >/sys/devices/system/edac/pci/check_pci_parity - - Disable: - echo "0" >/sys/devices/system/edac/pci/check_pci_parity - - -Parity Count: - - 'pci_parity_count' - - This attribute file will display the number of parity errors that - have been detected. - - - -MODULE PARAMETERS ------------------ - -Panic on UE control file: - - 'edac_mc_panic_on_ue' - - An uncorrectable error will cause a machine panic. This is usually - desirable. It is a bad idea to continue when an uncorrectable error - occurs - it is indeterminate what was uncorrected and the operating - system context might be so mangled that continuing will lead to further - corruption. If the kernel has MCE configured, then EDAC will never - notice the UE. - - LOAD TIME: module/kernel parameter: edac_mc_panic_on_ue=[0|1] - - RUN TIME: echo "1" > /sys/module/edac_core/parameters/edac_mc_panic_on_ue - - -Log UE control file: - - 'edac_mc_log_ue' - - Generate kernel messages describing uncorrectable errors. These errors - are reported through the system message log system. UE statistics - will be accumulated even when UE logging is disabled. - - LOAD TIME: module/kernel parameter: edac_mc_log_ue=[0|1] - - RUN TIME: echo "1" > /sys/module/edac_core/parameters/edac_mc_log_ue - - -Log CE control file: - - 'edac_mc_log_ce' - - Generate kernel messages describing correctable errors. These - errors are reported through the system message log system. - CE statistics will be accumulated even when CE logging is disabled. - - LOAD TIME: module/kernel parameter: edac_mc_log_ce=[0|1] - - RUN TIME: echo "1" > /sys/module/edac_core/parameters/edac_mc_log_ce - - -Polling period control file: - - 'edac_mc_poll_msec' - - The time period, in milliseconds, for polling for error information. - Too small a value wastes resources. Too large a value might delay - necessary handling of errors and might loose valuable information for - locating the error. 1000 milliseconds (once each second) is the current - default. Systems which require all the bandwidth they can get, may - increase this. - - LOAD TIME: module/kernel parameter: edac_mc_poll_msec=[0|1] - - RUN TIME: echo "1000" > /sys/module/edac_core/parameters/edac_mc_poll_msec - - -Panic on PCI PARITY Error: - - 'panic_on_pci_parity' - - - This control file enables or disables panicking when a parity - error has been detected. - - - module/kernel parameter: edac_panic_on_pci_pe=[0|1] - - Enable: - echo "1" > /sys/module/edac_core/parameters/edac_panic_on_pci_pe - - Disable: - echo "0" > /sys/module/edac_core/parameters/edac_panic_on_pci_pe - - - -EDAC device type ----------------- - -In the header file, edac_core.h, there is a series of edac_device structures -and APIs for the EDAC_DEVICE. - -User space access to an edac_device is through the sysfs interface. - -At the location /sys/devices/system/edac (sysfs) new edac_device devices will -appear. - -There is a three level tree beneath the above 'edac' directory. For example, -the 'test_device_edac' device (found at the bluesmoke.sourceforget.net website) -installs itself as: - - /sys/devices/systm/edac/test-instance - -in this directory are various controls, a symlink and one or more 'instance' -directories. - -The standard default controls are: - - log_ce boolean to log CE events - log_ue boolean to log UE events - panic_on_ue boolean to 'panic' the system if an UE is encountered - (default off, can be set true via startup script) - poll_msec time period between POLL cycles for events - -The test_device_edac device adds at least one of its own custom control: - - test_bits which in the current test driver does nothing but - show how it is installed. A ported driver can - add one or more such controls and/or attributes - for specific uses. - One out-of-tree driver uses controls here to allow - for ERROR INJECTION operations to hardware - injection registers - -The symlink points to the 'struct dev' that is registered for this edac_device. - -INSTANCES ---------- - -One or more instance directories are present. For the 'test_device_edac' case: - - test-instance0 - - -In this directory there are two default counter attributes, which are totals of -counter in deeper subdirectories. - - ce_count total of CE events of subdirectories - ue_count total of UE events of subdirectories - -BLOCKS ------- - -At the lowest directory level is the 'block' directory. There can be 0, 1 -or more blocks specified in each instance. - - test-block0 - - -In this directory the default attributes are: - - ce_count which is counter of CE events for this 'block' - of hardware being monitored - ue_count which is counter of UE events for this 'block' - of hardware being monitored - - -The 'test_device_edac' device adds 4 attributes and 1 control: - - test-block-bits-0 for every POLL cycle this counter - is incremented - test-block-bits-1 every 10 cycles, this counter is bumped once, - and test-block-bits-0 is set to 0 - test-block-bits-2 every 100 cycles, this counter is bumped once, - and test-block-bits-1 is set to 0 - test-block-bits-3 every 1000 cycles, this counter is bumped once, - and test-block-bits-2 is set to 0 - - - reset-counters writing ANY thing to this control will - reset all the above counters. - - -Use of the 'test_device_edac' driver should enable any others to create their own -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 is 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 currently 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 sequentially - maps channel/dimm into different csrows. - - For example, supposing 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 ability 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 display the - contents of the registers - -AMD64_EDAC REFERENCE DOCUMENTS USED ------------------------------------ -amd64_edac module is based on the following documents -(available from http://support.amd.com/en-us/search/tech-docs): - -1. Title: BIOS and Kernel Developer's Guide for AMD Athlon 64 and AMD - Opteron Processors - AMD publication #: 26094 - Revision: 3.26 - Link: http://support.amd.com/TechDocs/26094.PDF - -2. Title: BIOS and Kernel Developer's Guide for AMD NPT Family 0Fh - Processors - AMD publication #: 32559 - Revision: 3.00 - Issue Date: May 2006 - Link: http://support.amd.com/TechDocs/32559.pdf - -3. Title: BIOS and Kernel Developer's Guide (BKDG) For AMD Family 10h - Processors - AMD publication #: 31116 - Revision: 3.00 - Issue Date: September 07, 2007 - Link: http://support.amd.com/TechDocs/31116.pdf - -4. Title: BIOS and Kernel Developer's Guide (BKDG) for AMD Family 15h - Models 30h-3Fh Processors - AMD publication #: 49125 - Revision: 3.06 - Issue Date: 2/12/2015 (latest release) - Link: http://support.amd.com/TechDocs/49125_15h_Models_30h-3Fh_BKDG.pdf - -5. Title: BIOS and Kernel Developer's Guide (BKDG) for AMD Family 15h - Models 60h-6Fh Processors - AMD publication #: 50742 - Revision: 3.01 - Issue Date: 7/23/2015 (latest release) - Link: http://support.amd.com/TechDocs/50742_15h_Models_60h-6Fh_BKDG.pdf - -6. Title: BIOS and Kernel Developer's Guide (BKDG) for AMD Family 16h - Models 00h-0Fh Processors - AMD publication #: 48751 - Revision: 3.03 - Issue Date: 2/23/2015 (latest release) - Link: http://support.amd.com/TechDocs/48751_16h_bkdg.pdf - -CREDITS: -======== - -Written by Doug Thompson <dougthompson@xmission.com> -7 Dec 2005 -17 Jul 2007 Updated - -(c) Mauro Carvalho Chehab -05 Aug 2009 Nehalem interface - -EDAC authors/maintainers: - - Doug Thompson, Dave Jiang, Dave Peterson et al, - Mauro Carvalho Chehab - Borislav Petkov - original author: Thayne Harbaugh |