Commit 6b09448a authored by David Brownell's avatar David Brownell Committed by Greg Kroah-Hartman

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
...@@ -633,12 +633,27 @@ covers RTL which is used frequently with assembly language in the kernel. ...@@ -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 Kernel developers like to be seen as literate. Do mind the spelling
of kernel messages to make a good impression. Do not use crippled 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. Kernel messages do not have to be terminated with a period.
Printing numbers in parentheses (%d) adds no value and should be avoided. 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 Chapter 14: Allocating memory
...@@ -790,4 +805,5 @@ Kernel CodingStyle, by greg@kroah.com at OLS 2002: ...@@ -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/ http://www.kroah.com/linux/talks/ols_2002_kernel_codingstyle_talk/html/
-- --
Last updated on 2006-December-06. Last updated on 2007-July-13.
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