x86: round_jiffies() for i386 and x86-64 non-critical/corrected MCE polling

[pandora-kernel.git] / Documentation / CodingStyle

diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle
index b49b92e..7f1730f 100644 (file)
--- a/Documentation/CodingStyle
+++ b/Documentation/CodingStyle
@@ -218,6 +218,18 @@ no space after the prefix increment & decrement unary operators:
 
 and no space around the '.' and "->" structure member operators.
 
+Do not leave trailing whitespace at the ends of lines.  Some editors with
+"smart" indentation will insert whitespace at the beginning of new lines as
+appropriate, so you can start typing the next line of code right away.
+However, some such editors do not remove the whitespace if you end up not
+putting a line of code there, such as if you leave a blank line.  As a result,
+you end up with lines containing trailing whitespace.
+
+Git will warn you about patches that introduce trailing whitespace, and can
+optionally strip the trailing whitespace for you; however, if applying a series
+of patches, this may make later patches in the series fail by changing their
+context lines.
+
 
                Chapter 4: Naming
 
@@ -621,12 +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
 
@@ -726,6 +753,33 @@ need them.  Feel free to peruse that header file to see what else is already
 defined that you shouldn't reproduce in your code.
 
 
+               Chapter 18:  Editor modelines and other cruft
+
+Some editors can interpret configuration information embedded in source files,
+indicated with special markers.  For example, emacs interprets lines marked
+like this:
+
+-*- mode: c -*-
+
+Or like this:
+
+/*
+Local Variables:
+compile-command: "gcc -DMAGIC_DEBUG_FLAG foo.c"
+End:
+*/
+
+Vim interprets markers that look like this:
+
+/* vim:set sw=8 noet */
+
+Do not include any of these in source files.  People have their own personal
+editor configurations, and your source files should not override them.  This
+includes markers for indentation and mode configuration.  People may use their
+own custom mode, or may have some other magic method for making indentation
+work correctly.
+
+
 
                Appendix I: References
 
@@ -751,4 +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.
+