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 <lei...@debian.org>
> ---
> 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
> <lei...@debian.org>, Jul 7 2023
>
> Userdata append support by Matthew Wood <thepacketg...@gmail.com>, Jan 22
> 2024
>
> +Sysdata append support by Breno Leitao <lei...@debian.org>, Jan 15 2025
> +
> Please send bug reports to Matt Mackall <m...@selenic.com>
> Satyam Sharma <satyam.sha...@gmail.com>, and Cong Wang
> <xiyou.wangc...@gmail.com>
>
> @@ -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
