Improve documentation of Xref

* doc/emacs/maintaining.texi (Looking Up Identifiers): Document
xref-etags-mode.

diff --git a/doc/emacs/maintaining.texi b/doc/emacs/maintaining.texi
index 8f71b12b81fbd475748ba3a7bc9793298b5569fb..6ee2f2cc59779b7a58ad2f41b4df3b748e63c8ec 100644 (file)
--- a/doc/emacs/maintaining.texi
+++ b/doc/emacs/maintaining.texi
@@ -1812,6 +1812,8 @@ Find definition of identifier, and display it in a new frame
 @item M-,
 Go back to where you previously invoked @kbd{M-.} and friends
 (@code{xref-pop-marker-stack}).
+@item M-x xref-etags-mode
+Switch @code{xref} to use the @code{etags} backend.
 @end table
 
 @kindex M-.
@@ -1871,6 +1873,18 @@ where you were with @kbd{M-,}.  @kbd{M-,} allows you to retrace your
 steps to a depth determined by the variable
 @code{xref-marker-ring-length}, which defaults to 16.
 
+@findex xref-etags-mode
+  Some major modes install @code{xref} support facilities that might
+fail to find certain identifiers.  For example, in Emacs Lisp mode
+(@pxref{Lisp Eval}) @kbd{M-.} will by default find only functions and
+variables from Lisp packages that are loaded into the current Emacs
+session.  To find more identifiers, turn on the Xref Etags minor mode
+with @w{@kbd{M-x xref-etags-mode}}.  This command forces @code{xref}
+to use the @code{etags} backend (@pxref{Xref}).  (For this to work,
+you should first run @command{etags} to create the tags table, see
+@ref{Create Tags Table}.)
+
+
 @node Xref Commands
 @subsubsection Commands Available in the @file{*xref*} Buffer
 @cindex commands in @file{*xref*} buffers