* INSTALL: Describe installation of source and debug packages. (Bug#37527)

INSTALL

@@ -206,7 +206,7 @@ need to compile it.  For example, to compile Emacs with support for X
 and graphics libraries, you may need to install the X development
 package(s), and development versions of the jpeg, png, etc. packages.
 
-The names of the packages that you need varies according to the
+The names of the packages that you need vary according to the
 GNU/Linux distribution that you use, and the options that you want to
 configure Emacs with.  On Debian-based systems, you can install all the
 packages needed to build the installed version of Emacs with a command
@@ -214,6 +214,42 @@ like 'apt-get build-dep emacs' (on older systems, replace 'emacs' with
 eg 'emacs25').  On Red Hat-based systems, the corresponding command is
 'dnf builddep emacs' (on older systems, use 'yum-builddep' instead).
 
+* GNU/Linux source and debug packages
+
+Many GNU/Linux systems provide separate packages containing the
+sources and debug symbols of Emacs.  They are useful if you want to
+check the source code of Emacs primitive functions or debug Emacs on
+the C level.
+
+The names of the packages that you need vary according to the
+GNU/Linux distribution that you use.  On Debian-based systems, you can
+install a source package of Emacs with a command like 'apt-get source
+emacs' (on older systems, replace 'emacs' with eg 'emacs25').  The
+target directory for unpacking the source tree is the current
+directory.  On Red Hat-based systems, the corresponding command is
+'dnf install emacs-debugsource', with target directory /usr/src/debug
+(this requires to add the *-debuginfo repositories first, via 'dnf
+config-manager --set-enabled fedora-debuginfo updates-debuginfo').
+
+Once you have installed the source package, for example at
+/path/to/emacs-26.1, add the following line to your startup file:
+
+     (setq find-function-C-source-directory
+           "/path/to/emacs-26.1/src")
+
+The installation directory of the Emacs source package will contain
+the exact package name and version number Emacs is installed on your
+system.  If a new Emacs package is installed, the source package must
+be reinstalled as well, and the setting in your startup file must be
+updated.
+
+Emacs debugging symbols are distributed by a debug package.  It does
+not exist for every released Emacs package, this depends on the
+distribution.  On Debian-based systems, you can install a debug
+package of Emacs with a command like 'apt-get install emacs-dbg' (on
+older systems, replace 'emacs' with eg 'emacs25').  On Red Hat-based
+systems, the corresponding command is 'dnf debuginfo-install emacs'.
+
 
 DETAILED BUILDING AND INSTALLATION: