From akpm@linux-foundation.org Fri Jul 13 16:32:19 2007 From: David Brownell Date: Fri, 13 Jul 2007 16:32:09 -0700 Subject: dev_vdbg() documentation To: mm-commits@vger.kernel.org Cc: david-b@pacbell.net, dbrownell@users.sourceforge.net, greg@kroah.com Message-ID: <200707132332.l6DNW9iX028676@imap1.linux-foundation.org> From: David Brownell Update CodingStyle to talk about "-DDEBUG" message conventions and the new "-DVERBOSE_DEBUG" convention. Signed-off-by: David Brownell Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- Documentation/CodingStyle | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) --- a/Documentation/CodingStyle +++ b/Documentation/CodingStyle @@ -633,12 +633,27 @@ covers RTL which is used frequently with Kernel developers like to be seen as literate. Do mind the spelling of kernel messages to make a good impression. Do not use crippled -words like "dont" and use "do not" or "don't" instead. +words like "dont"; use "do not" or "don't" instead. Make the messages +concise, clear, and unambiguous. Kernel messages do not have to be terminated with a period. Printing numbers in parentheses (%d) adds no value and should be avoided. +There are a number of driver model diagnostic macros in +which you should use to make sure messages are matched to the right device +and driver, and are tagged with the right level: dev_err(), dev_warn(), +dev_info(), and so forth. For messages that aren't associated with a +particular device, defines pr_debug() and pr_info(). + +Coming up with good debugging messages can be quite a challenge; and once +you have them, they can be a huge help for remote troubleshooting. Such +messages should be compiled out when the DEBUG symbol is not defined (that +is, by default they are not included). When you use dev_dbg() or pr_debug(), +that's automatic. Many subsystems have Kconfig options to turn on -DDEBUG. +A related convention uses VERBOSE_DEBUG to add dev_vdbg() messages to the +ones already enabled by DEBUG. + Chapter 14: Allocating memory @@ -790,4 +805,5 @@ Kernel CodingStyle, by greg@kroah.com at http://www.kroah.com/linux/talks/ols_2002_kernel_codingstyle_talk/html/ -- -Last updated on 2006-December-06. +Last updated on 2007-July-13. +