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Commit 6b09448a authored by David Brownell's avatar David Brownell Committed by Greg Kroah-Hartman
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dev_vdbg() documentation 



Update CodingStyle to talk about "-DDEBUG" message conventions and the
new "-DVERBOSE_DEBUG" convention.

Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent aebdc3b4

Documentation/CodingStyle

+18 −2
Original line number Diff line number Diff line
@@ -633,12 +633,27 @@ covers RTL which is used frequently with assembly language in the kernel. 


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 <linux/device.h>

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, <linux/kernel.h> 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 OLS 2002: 
http://www.kroah.com/linux/talks/ols_2002_kernel_codingstyle_talk/html/



--

Last updated on 2006-December-06.
 
Last updated on 2007-July-13.