path: root/Documentation/CodingStyle
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authorDavid Brownell <>2007-07-13 16:32:09 -0700
committerGreg Kroah-Hartman <>2007-07-18 15:49:50 -0700
commit6b09448ab81e90e59c09cfbc6d0d612dc84a2b1d (patch)
tree6c2fc89767cb438dc168dc867c9931b5425c5f46 /Documentation/CodingStyle
parentaebdc3b450a3febf7d7d00cd2235509055ec7082 (diff)
dev_vdbg() documentation
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 <>
Diffstat (limited to 'Documentation/CodingStyle')
1 files changed, 18 insertions, 2 deletions
diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle
index a667eb1fc26e..7f1730f1a1ae 100644
--- a/Documentation/CodingStyle
+++ b/Documentation/CodingStyle
@@ -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 at OLS 2002:
-Last updated on 2006-December-06.
+Last updated on 2007-July-13.