diff options
Diffstat (limited to 'lib/Kconfig.debug')
| -rw-r--r-- | lib/Kconfig.debug | 33 |
1 files changed, 21 insertions, 12 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 6777153f18f3..e11934177030 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -3,12 +3,16 @@ config PRINTK_TIME bool "Show timing information on printks" depends on PRINTK help - Selecting this option causes timing information to be - included in printk output. This allows you to measure - the interval between kernel operations, including bootup - operations. This is useful for identifying long delays - in kernel startup. Or add printk.time=1 at boot-time. - See Documentation/kernel-parameters.txt + Selecting this option causes time stamps of the printk() + messages to be added to the output of the syslog() system + call and at the console. + + The timestamp is always recorded internally, and exported + to /dev/kmsg. This flag just specifies if the timestamp should + be included, not that the timestamp is recorded. + + The behavior is also controlled by the kernel command line + parameter printk.time=1. See Documentation/kernel-parameters.txt config DEFAULT_MESSAGE_LOGLEVEL int "Default message log level (1-7)" @@ -1205,8 +1209,13 @@ config DYNAMIC_DEBUG otherwise be available at runtime. These messages can then be enabled/disabled based on various levels of scope - per source file, function, module, format string, and line number. This mechanism - implicitly enables all pr_debug() and dev_dbg() calls. The impact of - this compile option is a larger kernel text size of about 2%. + implicitly compiles in all pr_debug() and dev_dbg() calls, which + enlarges the kernel text size by about 2%. + + If a source file is compiled with DEBUG flag set, any + pr_debug() calls in it are enabled by default, but can be + disabled at runtime as below. Note that DEBUG flag is + turned on by many CONFIG_*DEBUG* options. Usage: @@ -1223,16 +1232,16 @@ config DYNAMIC_DEBUG lineno : line number of the debug statement module : module that contains the debug statement function : function that contains the debug statement - flags : 'p' means the line is turned 'on' for printing + flags : '=p' means the line is turned 'on' for printing format : the format used for the debug statement From a live system: nullarbor:~ # cat <debugfs>/dynamic_debug/control # filename:lineno [module]function flags format - fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012" - fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012" - fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012" + fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" + fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" + fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" Example usage: |