path: root/lib/Kconfig.debug

menu "printk and dmesg options"

config PRINTK_TIME
	bool "Show timing information on printks"
	depends on PRINTK
	help
	  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)"
	range 1 7
	default "4"
	help
	  Default log level for printk statements with no specified priority.

	  This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
	  that are auditing their logs closely may want to set it to a lower
	  priority.

config BOOT_PRINTK_DELAY
	bool "Delay each boot printk message by N milliseconds"
	depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
	help
	  This build option allows you to read kernel boot messages
	  by inserting a short delay after each one.  The delay is
	  specified in milliseconds on the kernel command line,
	  using "boot_delay=N".

	  It is likely that you would also need to use "lpj=M" to preset
	  the "loops per jiffie" value.
	  See a previous boot log for the "lpj" value to use for your
	  system, and then set "lpj=M" before setting "boot_delay=N".
	  NOTE:  Using this option may adversely affect SMP systems.
	  I.e., processors other than the first one may not boot up.
	  BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
	  what it believes to be lockup conditions.

config DYNAMIC_DEBUG
	bool "Enable dynamic printk() support"
	default n
	depends on PRINTK
	depends on DEBUG_FS
	help

	  Compiles debug level messages into the kernel, which would not
	  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 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:

	  Dynamic debugging is controlled via the 'dynamic_debug/control' file,
	  which is contained in the 'debugfs' filesystem. Thus, the debugfs
	  filesystem must first be mounted before making use of this feature.
	  We refer the control file as: <debugfs>/dynamic_debug/control. This
	  file contains a list of the debug statements that can be enabled. The
	  format for each line of the file is:

		filename:lineno [module]function flags format

	  filename : source file of the debug statement
	  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
          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"

	  Example usage:

		// enable the message at line 1603 of file svcsock.c
		nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
						<debugfs>/dynamic_debug/control

		// enable all the messages in file svcsock.c
		nullarbor:~ # echo -n 'file svcsock.c +p' >
						<debugfs>/dynamic_debug/control

		// enable all the messages in the NFS server module
		nullarbor:~ # echo -n 'module nfsd +p' >
						<debugfs>/dynamic_debug/control

		// enable all 12 messages in the function svc_process()
		nullarbor:~ # echo -n 'func svc_process +p' >
						<debugfs>/dynamic_debug/control

		// disable all 12 messages in the function svc_process()
		nullarbor:~ # echo -n 'func svc_process -p' >
						<debugfs>/dynamic_debug/control

	  See Documentation/dynamic-debug-howto.txt for additional information.

endmenu # "printk and dmesg options"

menu "Compile-time checks and compiler options"

config DEBUG_INFO
	bool "Compile the kernel with debug info"
	depends on DEBUG_KERNEL
	help
          If you say Y here the resulting kernel image will include
	  debugging info resulting in a larger kernel image.
	  This adds debug symbols to the kernel and modules (gcc -g), and
	  is needed if you intend to use kernel crashdump or binary object
	  tools like crash, kgdb, LKCD, gdb, etc on the kernel.
	  Say Y here only if you plan to debug the kernel.

	  If unsure, say N.

config DEBUG_INFO_REDUCED
	bool "Reduce debugging information"
	depends on DEBUG_INFO
	help
	  If you say Y here gcc is instructed to generate less debugging
	  information for structure types. This means that tools that
	  need full debugging information (like kgdb or systemtap) won't
	  be happy. But if you merely need debugging information to
	  resolve line numbers there is no loss. Advantage is that
	  build directory object sizes shrink dramatically over a full
	  DEBUG_INFO build and compile times are reduced too.
	  Only works with newer gcc versions.

config ENABLE_WARN_DEPRECATED
	bool "Enable __deprecated logic"
	default y
	help
	  Enable the __deprecated logic in the kernel build.
	  Disable this to suppress the "warning: 'foo' is deprecated
	  (decl