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[2a03:2880:30ff:74::face:b00c]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5cf03b7e9c1sm7150081a12.30.2024.11.13.07.11.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Nov 2024 07:11:18 -0800 (PST) From: Breno Leitao Date: Wed, 13 Nov 2024 07:10:54 -0800 Subject: [PATCH net-next 3/4] netconsole: docs: Add documentation for CPU number auto-population Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20241113-netcon_cpu-v1-3-d187bf7c0321@debian.org> References: <20241113-netcon_cpu-v1-0-d187bf7c0321@debian.org> In-Reply-To: <20241113-netcon_cpu-v1-0-d187bf7c0321@debian.org> To: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Jonathan Corbet , Shuah Khan Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, Breno Leitao , max@kutsevol.com, thepacketgeek@gmail.com, vlad.wing@gmail.com, davej@codemonkey.org.uk X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2825; i=leitao@debian.org; h=from:subject:message-id; bh=IpyXc0ozD1GMB+Il96IkWK5dAeJgnotpsHJ8YdD/teM=; b=owEBbQKS/ZANAwAIATWjk5/8eHdtAcsmYgBnNMGNzGRw6kxr2xG4dDZWgxH4YZ0MO8P17DbTm zuXW0wPnA6JAjMEAAEIAB0WIQSshTmm6PRnAspKQ5s1o5Of/Hh3bQUCZzTBjQAKCRA1o5Of/Hh3 bXu/D/9ZPm74waC8ijNe4fg4/CahtsYlyec/NF+SAZ9vDqSx4mlF5v9Z/qwc+Hp4lzlug3NTo1k MzvOCTWK+fn28Ny2ImckvQ3rrYgCFoHdRnvqGep6rC76ZVSiy1X9cAqJ9VyycvbDdGJdRsgh429 ZYu4nrTn3H2w/kYqt1xjhsIBKyabNY3oROeAMeFlmg4dnSy7QIdtocsdwIhEZs0vM+o+WzBHZCK VyiTURNjwKAgpt4kTVkli4yA+0ziwR97h4khTYoCUNqg8r8kXcArN6L7X88f8iQvg+h+dUBhSsp JVuUMK5aMAdote/BInKBMAJab60LcmY4jWq06qCmrs5GEffzN7Cja/ISyeGGN43af5l6O00P5zg eaPjcOt3Hes7byvM+6PZBuvqu2SZyaT3Bajj9bZCVbhVrxC1dGMfTYmg7lfJuxTWDq0Ai49pf0z O+9+SwHO+VE5T30RQAMEoQBL6J0KX4Zc+Hbd5UKY4qVghkR3IF6FrVUkfhvcPdmx/zTndqbRfY5 26Cr0ukcwtkUPK5wsuss1IDPo1XPJRMEHxXygq3MuLc4WjFRGS65K1j3v6tL2Y7GqbMRazfrXED DfEoCeVwoioYVL94BwVLOEV3zrFekhJ+xVfR/NGBbL16FcjLhFLFFnOIG1ws4nodvPu9cG+lPz1 U5hWPn8TV/mxb2w== X-Developer-Key: i=leitao@debian.org; a=openpgp; fpr=AC8539A6E8F46702CA4A439B35A3939FFC78776D Update the netconsole documentation to explain the new feature that allows automatic population of the CPU number in the userdata field. 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 --- Documentation/networking/netconsole.rst | 44 +++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/Documentation/networking/netconsole.rst b/Documentation/networking/netconsole.rst index d55c2a22ec7af0e687b76176c9171eb1b19013bd..a1b269196be390b5f88a6eca77f6676c67c05720 100644 --- a/Documentation/networking/netconsole.rst +++ b/Documentation/networking/netconsole.rst @@ -237,6 +237,50 @@ 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 +`populate_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 in the +userdata field. + +To enable the CPU number auto-population:: + + echo 1 > /sys/kernel/config/netconsole/target1/userdata/populate_cpu_nr + +When this option is enabled, the netconsole messages will include an additional +line in the userdata field with the format `cpu=`. 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: =================