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2025-06-18docs: netconsole: document msgid featureGustavo Luiz Duarte
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> Signed-off-by: David S. Miller <davem@davemloft.net>
2025-03-21docs: netconsole: document release featureBreno Leitao
Add documentation explaining the kernel release auto-population feature in netconsole. This feature appends kernel version information to the userdata dictionary in every message sent when enabled via the `release_enabled` file in the configfs hierarchy. Signed-off-by: Breno Leitao <leitao@debian.org> Reviewed-by: Simon Horman <horms@kernel.org> Link: https://patch.msgid.link/20250314-netcons_release-v1-6-07979c4b86af@debian.org Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-19netconsole: allow selection of egress interface via MAC addressUday Shankar
Currently, netconsole has two methods of configuration - module parameter and configfs. The former interface allows for netconsole activation earlier during boot (by specifying the module parameter on the kernel command line), so it is preferred for debugging issues which arise before userspace is up/the configfs interface can be used. The module parameter syntax requires specifying the egress interface name. This requirement makes it hard to use for a couple reasons: - The egress interface name can be hard or impossible to predict. For example, installing a new network card in a system can change the interface names assigned by the kernel. - When constructing the module parameter, one may have trouble determining the original (kernel-assigned) name of the interface (which is the name that should be given to netconsole) if some stable interface naming scheme is in effect. A human can usually look at kernel logs to determine the original name, but this is very painful if automation is constructing the parameter. For these reasons, allow selection of the egress interface via MAC address when configuring netconsole using the module parameter. Update the netconsole documentation with an example of the new syntax. Selection of egress interface by MAC address via configfs is far less interesting (since when this interface can be used, one should be able to easily convert between MAC address and interface name), so it is left unimplemented. Signed-off-by: Uday Shankar <ushankar@purestorage.com> Reviewed-by: Breno Leitao <leitao@debian.org> Tested-by: Breno Leitao <leitao@debian.org> Reviewed-by: Simon Horman <horms@kernel.org> Link: https://patch.msgid.link/20250312-netconsole-v6-2-3437933e79b8@purestorage.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-04netconsole: docs: document the task name featureBreno Leitao
Add documentation for the netconsole task name feature in Documentation/networking/netconsole.rst. This explains how to enable task name via configfs and demonstrates the output format. The documentation includes: - How to enable/disable the feature via taskname_enabled - The format of the task name in the output - An example showing the task name appearing in messages Signed-off-by: Breno Leitao <leitao@debian.org> Reviewed-by: Simon Horman <horms@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-02-10netconsole: docs: Add documentation for CPU number auto-populationBreno Leitao
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@debian.org> Reviewed-by: Simon Horman <horms@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2024-12-04netcons: Add udp send fail statistics to netconsoleMaksym Kutsevol
Enhance observability of netconsole. Packet sends can fail. Start tracking at least two failure possibilities: ENOMEM and NET_XMIT_DROP for every target. Stats are exposed via an additional attribute in CONFIGFS. The exposed statistics allows easier debugging of cases when netconsole messages were not seen by receivers, eliminating the guesswork if the sender thinks that messages in question were sent out. Stats are not reset on enable/disable/change remote ip/etc, they belong to the netcons target itself. Reported-by: Breno Leitao <leitao@debian.org> Closes: https://lore.kernel.org/all/ZsWoUzyK5du9Ffl+@gmail.com/ Signed-off-by: Maksym Kutsevol <max@kutsevol.com> Link: https://patch.msgid.link/20241202-netcons-add-udp-send-fail-statistics-to-netconsole-v5-2-70e82239f922@kutsevol.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-11net: netconsole: Add continuation line prefix to userdata messagesMatthew Wood
Add a space (' ') prefix to every userdata line to match docs for dev-kmsg. To account for this extra character in each userdata entry, reduce userdata entry names (directory name) from 54 characters to 53. According to the dev-kmsg docs, a space is used for subsequent lines to mark them as continuation lines. > A line starting with ' ', is a continuation line, adding > key/value pairs to the log message, which provide the machine > readable context of the message, for reliable processing in > userspace. Testing for this patch:: cd /sys/kernel/config/netconsole && mkdir cmdline0 cd cmdline0 mkdir userdata/test && echo "hello" > userdata/test/value mkdir userdata/test2 && echo "hello2" > userdata/test2/value echo "message" > /dev/kmsg Outputs:: 6.8.0-rc5-virtme,12,493,231373579,-;message test=hello test2=hello2 And I confirmed all testing works as expected from the original patchset Fixes: df03f830d099 ("net: netconsole: cache userdata formatted string in netconsole_target") Signed-off-by: Matthew Wood <thepacketgeek@gmail.com> Reviewed-by: Breno Leitao <leitao@debian.org> Link: https://lore.kernel.org/r/20240308002525.248672-1-thepacketgeek@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-02-09net: netconsole: add docs for appending netconsole user dataMatthew Wood
Add a new User Data section to the netconsole docs to describe the appending of user data capability (for netconsole dynamic configuration) with usage and netconsole output examples. Co-developed-by: Breno Leitao <leitao@debian.org> Signed-off-by: Breno Leitao <leitao@debian.org> Signed-off-by: Matthew Wood <thepacketgeek@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-10-13Documentation: netconsole: add support for cmdline targetsBreno Leitao
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@debian.org> Link: https://lore.kernel.org/r/20231012111401.333798-5-leitao@debian.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-07-18netconsole: Append kernel version to messageBreno Leitao
Create a new netconsole runtime option that prepends the kernel version in the netconsole message. This is useful to map kernel messages to kernel version in a simple way, i.e., without checking somewhere which kernel version the host that sent the message is using. If this option is selected, then the "<release>," is prepended before the netconsole message. This is an example of a netconsole output, with release feature enabled: 6.4.0-01762-ga1ba2ffe946e;12,426,112883998,-;this is a test Cc: Dave Jones <davej@codemonkey.org.uk> Signed-off-by: Breno Leitao <leitao@debian.org> Link: https://lore.kernel.org/r/20230714111330.3069605-1-leitao@debian.org Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2023-01-31Documentation: networking: correct spellingRandy Dunlap
Correct spelling problems for Documentation/networking/ as reported by codespell. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-doc@vger.kernel.org Cc: Jiri Pirko <jiri@nvidia.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: netdev@vger.kernel.org Link: https://lore.kernel.org/r/20230129231053.20863-5-rdunlap@infradead.org Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2020-04-30docs: networking: convert netconsole.txt to ReSTMauro Carvalho Chehab
- add SPDX header; - add a document title; - mark code blocks and literals as such; - mark tables as such; - add notes markups; - adjust identation, whitespaces and blank lines; - add to networking/index.rst. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>