Add documentation explaining the msgid feature in netconsole.
This feature appends unique id to the userdata dictionary. The message ID is populated from a per-target 32 bit counter which is incremented for each message sent to the target. This allows a target to detect if messages are dropped before reaching the target.
Signed-off-by: Gustavo Luiz Duarte gustavold@gmail.com --- Documentation/networking/netconsole.rst | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)
diff --git a/Documentation/networking/netconsole.rst b/Documentation/networking/netconsole.rst index a0076b542e9c..42a0acf2eb5e 100644 --- a/Documentation/networking/netconsole.rst +++ b/Documentation/networking/netconsole.rst @@ -340,6 +340,28 @@ In this example, the message was sent by CPU 42. cpu=42 # kernel-populated value
+Message ID auto population in userdata +-------------------------------------- + +Within the netconsole configfs hierarchy, there is a file named `msgid_enabled` +located in the `userdata` directory. This file controls the message ID +auto-population feature, which assigns a unique id to each message sent to a +given target and appends the ID to userdata dictionary in every message sent. + +The message ID is built from a per-target 32 bit counter that is incremented +for every message sent to the target. This ID can be used by the target to +detect if messages were dropped before reaching the target. + +Example:: + + echo "This is message #1" > /dev/kmsg + echo "This is message #2" > /dev/kmsg + 13,434,54928466,-;This is message #1 + msgid=1 + 13,435,54934019,-;This is message #2 + msgid=2 + + Extended console: =================