Let's remove some redundant descriptions in the usage documentation of the logger, and make it clear.

Signed-off-by: Lianbo Jiang lijiang@redhat.com --- kexec-kdump-howto.txt | 65 ++++++++++++++++++++++++------------------- 1 file changed, 37 insertions(+), 28 deletions(-)

diff --git a/kexec-kdump-howto.txt b/kexec-kdump-howto.txt index 5f57a8428e4f..d2dba492ed60 100644 --- a/kexec-kdump-howto.txt +++ b/kexec-kdump-howto.txt @@ -888,35 +888,44 @@ Debugging Tips

- Using the logger to output kdump log messages

- Currently, kdump messages are printed with the 'echo' command or redirect - to console, and which does not support to output kdump messages according - to the log level. - - That is not convenient to debug kdump issues, we usually need to capture - additional debugging information via the modification of the options or the - scripts like kdumpctl, mkdumprd, etc. Because there is no complete debugging - messages, which could waste valuable time. - - To cope with this challenging, we introduce the logger to output the kdump - messages according to the log level, and provide a chance to save logs to - the journald if the journald service is available, and then dump all logs - to a file, otherwise dump the logs with the dmesg to a file. - - Logging is controlled by following global variables: - - @var kdump_stdloglvl - logging level to standard error (console output) - - @var kdump_sysloglvl - logging level to syslog (by logger command) - - @var kdump_kmsgloglvl - logging level to /dev/kmsg (only for boot-time) - If any of the variables is not set, this function set it to default: - - @var kdump_stdloglvl=4 (info) - - @var kdump_sysloglvl=4 (info) - - @var kdump_kmsgloglvl=0 (no logging) + You can configure the kdump log level in the /etc/sysconfig/kdump. + For example: + + kdump_sysloglvl=4 + kdump_stdloglvl=4 + + The above configurations indicate that kdump messages will be printed to the + console and journald if the journald service is enabled, and the log level is + set to 4(info). This is also the current default log level.

Logging levels: fatal(1),error(2),warn(3),info(4),debug(5),trace(6)

- We can easily configure the above variables in the /etc/sysconfig/kdump. For - example: - kdump_sysloglvl=5 - kdump_stdloglvl=5 + The FATAL level designates very severe error events that will presumably lead + the application to abort.

- The above configurations indicate that kdump messages will be printed to the - console and journald if the journald service is enabled. + The ERROR level designates error events that might still allow the application + to continue running. + + The WARN level designates potentially harmful situations. + + The INFO level designates informational messages that highlight the progress + of the application at coarse-grained level. + + The DEBUG level designates fine-grained informational events that are most + useful to debug an application. + + The TRACE level designates finer-grained informational events than the DEBUG. + + Currently, the logger works in both the first kernel(kdump service debugging) + and the second kernel. + + In the first kernel, you can find the historical logs in the /var/log/messages + or use the journalctl command to check kdump service debugging information. In + addition, the 'kexec -d' debugging messages are also saved to /var/log/kdump.log + in the first kernel. + + In the second kernel, put the kexec-dmesg.log to a same directory with the + vmcore, the log file includes the debugging messages like dmesg and journald + logs. + + For more details, please refer to the /etc/sysconfig/kdump.