mcelog client/server protocol
mcelog in daemon mode supports a simple client-server protocol. The server is normally queried from mcelog --client, but can be also queried by other agents.
Important: Before writing a query agent consider setting up triggers, that run custom scripts when specific error thresholds per hardware unit are crossed. For many problems these are the better answers.
Specification
The communication happens over a SOCK_STREAM AF_UNIX socket on the local host. The file name of the unix socket is configurable. The default is /var/run/mcelog-client. The client connects over the unix socket to the server.The protocol is an text based protocol. The client sends a command. The server answers with text. The protocol is case sensitive. Each line is finished with unix newline.
The following grammar is in EBNF
Valid commands
| Command | Semantics |
| ping | Server answers with pong |
| dump | Dump memory errors. Can be followed by modifiers. |
| pages | Dump errors per page |
dump command
The dump command can have the following modifiers separated by spaces: bios to dump BIOS DMI information and all to dump even errors that did not cross a threshold.DUMP = "dump" ["bios"] ["all"]
The reply format is a ASCII format that needs to be parsed by the client. The first line is "Memory errors". Then a list of object description follows.
REPLY = "Memory errors\n" { OBJECT }
OBJECT = IDENTIFIERS "\n" { ERRORTYPE "\n" }
IDENTIFIERS = IDENTIFIER { IDENTIFIER }
IDENTIFIER = ID number
ID = [a-zA-Z_][a-zA-Z0-9_]+
NUMBER = [0-9]+
ERRORTYPE = error-type ":" "\n" { "\t" NUMBER error-description "\n" }
dump example output
Memory errors SOCKET 0 CHANNEL any DIMM any corrected memory errors: 1 total 1 in 24h uncorrected memory errors: 0 total 0 in 24h SOCKET 0 CHANNEL 0 DIMM any corrected memory errors: 1 total 1 in 24h uncorrected memory errors: 0 total 0 in 24h
pages command
The pages command dumps a list of errors per memory page. The first line is "Per page corrected memory statistics". The each line consists of a hex number, followed by :, and a bucket description. The bucket description is of the form: total X seen in "Y". X is the number of errors seen in the time period of the bucket, Y is the string description of the bucket configuration. Followed by an offline or online string. Empty lines should be ignored.
PAGE-REPLY = description ":" "\n" { PAGE }
description = [a-fA-Z 0-9]+
PAGE = NUMBER ":" "total" NUMBER "seen" "in" "\"" description "\"" ["online" | "offline"]
pages example output
Per page corrected memory statistics: 2320000: total 1 seen "1 in 24h" online 3d8c000: total 1 seen "1 in 24h" online 75df000: total 1 seen "1 in 24h" online 7b15000: total 1 seen "1 in 24h" online