On 1/15/25 5:35 AM, Breno Leitao wrote: > Update the netconsole documentation to explain the new feature that > allows automatic population of the CPU number. > > The key changes include introducing a new section titled "CPU number > auto population in userdata", explaining how to enable the CPU number > auto-population feature by writing to the "populate_cpu_nr" file in the > netconsole configfs hierarchy. > > This documentation update ensures users are aware of the new CPU number > auto-population functionality and how to leverage it for better > demultiplexing and visibility of parallel netconsole output. > > Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx> > --- > Documentation/networking/netconsole.rst | 45 +++++++++++++++++++++++++++++++++ > 1 file changed, 45 insertions(+) > > diff --git a/Documentation/networking/netconsole.rst b/Documentation/networking/netconsole.rst > index 94c4680fdf3e7e1a0020d11b44547acfd68072a5..bc9ccebdae7adadd7c57aef20a726536d7ab3173 100644 > --- a/Documentation/networking/netconsole.rst > +++ b/Documentation/networking/netconsole.rst > @@ -17,6 +17,8 @@ Release prepend support by Breno Leitao <leitao@xxxxxxxxxx>, Jul 7 2023 > > Userdata append support by Matthew Wood <thepacketgeek@xxxxxxxxx>, Jan 22 2024 > > +Sysdata append support by Breno Leitao <leitao@xxxxxxxxxx>, Jan 15 2025 > + > Please send bug reports to Matt Mackall <mpm@xxxxxxxxxxx> > Satyam Sharma <satyam.sharma@xxxxxxxxx>, and Cong Wang <xiyou.wangcong@xxxxxxxxx> > > @@ -238,6 +240,49 @@ Delete `userdata` entries with `rmdir`:: > > It is recommended to not write user data values with newlines. > > +CPU number auto population in userdata > +-------------------------------------- > + > +Inside the netconsole configfs hierarchy, there is a file called > +`cpu_nr` under the `userdata` directory. This file is used to enable or disable > +the automatic CPU number population feature. This feature automatically > +populate the CPU number that is sending the message. populates > + > +To enable the CPU number auto-population:: > + > + echo 1 > /sys/kernel/config/netconsole/target1/userdata/cpu_nr > + > +When this option is enabled, the netconsole messages will include an additional > +line in the userdata field with the format `cpu=<cpu_number>`. This allows the > +receiver of the netconsole messages to easily differentiate and demultiplex > +messages originating from different CPUs, which is particularly useful when > +dealing with parallel log output. > + > +Example:: > + > + echo "This is a message" > /dev/kmsg > + 12,607,22085407756,-;This is a message > + cpu=42 > + > +In this example, the message was sent by CPU 42. > + > +.. note:: > + > + If the user has set a conflicting `cpu` key in the userdata dictionary, > + both keys will be reported, with the kernel-populated entry appearing after > + the user one. For example:: > + > + # User-defined CPU entry > + mkdir -p /sys/kernel/config/netconsole/target1/userdata/cpu > + echo "1" > /sys/kernel/config/netconsole/target1/userdata/cpu/value > + > + Output might look like:: > + > + 12,607,22085407756,-;This is a message > + cpu=1 > + cpu=42 # kernel-populated value > + > + > Extended console: > ================= > > -- ~Randy
