linux-kernel - Re: [PATCH net-next v4 4/4] Documentation: netconsole: add support for cmdline targets

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Message-ID: <ZSs4gvm8fx+BpfcQ@google.com>
Date:   Sat, 14 Oct 2023 17:55:30 -0700
From:   Joel Becker <jlbec@...lplan.org>
To:     Breno Leitao <leitao@...ian.org>
Cc:     kuba@...nel.org, davem@...emloft.net, pabeni@...hat.com,
        Eric Dumazet <edumazet@...gle.com>,
        Jonathan Corbet <corbet@....net>, hch@....de,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        horms@...nel.org,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>
Subject: Re: [PATCH net-next v4 4/4] Documentation: netconsole: add support
 for cmdline targets

On Thu, Oct 12, 2023 at 04:14:01AM -0700, Breno Leitao wrote:
> With the previous patches, there is no more limitation at modifying the
> targets created at boot time (or module load time).
> 
> Document the way on how to create the configfs directories to be able to
> modify these netconsole targets.
> 
> The design discussion about this topic could be found at:
> https://lore.kernel.org/all/ZRWRal5bW93px4km@gmail.com/
> 
> Signed-off-by: Breno Leitao <leitao@...ian.org>
Reviewed-by: Joel Becker <jlbec@...lplan.org>

> ---
>  Documentation/networking/netconsole.rst | 22 +++++++++++++++++++---
>  1 file changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/networking/netconsole.rst b/Documentation/networking/netconsole.rst
> index 7a9de0568e84..390730a74332 100644
> --- a/Documentation/networking/netconsole.rst
> +++ b/Documentation/networking/netconsole.rst
> @@ -99,9 +99,6 @@ Dynamic reconfiguration:
>  Dynamic reconfigurability is a useful addition to netconsole that enables
>  remote logging targets to be dynamically added, removed, or have their
>  parameters reconfigured at runtime from a configfs-based userspace interface.
> -[ Note that the parameters of netconsole targets that were specified/created
> -from the boot/module option are not exposed via this interface, and hence
> -cannot be modified dynamically. ]
>  
>  To include this feature, select CONFIG_NETCONSOLE_DYNAMIC when building the
>  netconsole module (or kernel, if netconsole is built-in).
> @@ -155,6 +152,25 @@ You can also update the local interface dynamically. This is especially
>  useful if you want to use interfaces that have newly come up (and may not
>  have existed when netconsole was loaded / initialized).
>  
> +Netconsole targets defined at boot time (or module load time) with the
> +`netconsole=` param are assigned the name `cmdline<index>`.  For example, the
> +first target in the parameter is named `cmdline0`.  You can control and modify
> +these targets by creating configfs directories with the matching name.
> +
> +Let's suppose you have two netconsole targets defined at boot time::
> +
> + netconsole=4444@...0.0.1/eth1,9353@...0.0.2/12:34:56:78:9a:bc;4444@...0.0.1/eth1,9353@...0.0.3/12:34:56:78:9a:bc
> +
> +You can modify these targets in runtime by creating the following targets::
> +
> + mkdir cmdline0
> + cat cmdline0/remote_ip
> + 10.0.0.2
> +
> + mkdir cmdline1
> + cat cmdline1/remote_ip
> + 10.0.0.3
> +
>  Extended console:
>  =================
>  
> -- 
> 2.34.1
> 

-- 

	f/8 and be there.

			http://www.jlbec.org/
			jlbec@...lplan.org