1 files changed, 39 insertions, 0 deletions

diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle
index b49b92edb396..a667eb1fc26e 100644
--- 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
 
@@ -726,6 +738,33 @@ 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