Add requirement for plugin_is_GPL_compatible symbol in loaded objects.

1 files changed, 20 insertions, 0 deletions

diff --git a/doc/make.texi b/doc/make.texi
index e3e5135d..d1ceefb5 100644
--- a/doc/make.texi
+++ b/doc/make.texi
@@ -11058,6 +11058,24 @@ functions may make use of the @code{gmk_expand} and @code{gmk_eval}
 routines to perform their tasks, then optionally return a string as
 the result of the function expansion.
 
+@subsubheading Loaded Object Licensing
+@cindex loaded object licensing
+@cindex plugin_is_GPL_compatible
+
+Every dynamic extension should define the global symbol
+@code{plugin_is_GPL_compatible} to assert that it has been licensed
+under a GPL-compatible license.  If this symbol does not exist,
+@code{make} emits a fatal error and exits when it tries to load your
+extension.
+
+The declared type of the symbol should be @code{int}. It does not need
+to be in any allocated section, though.  The code merely asserts that
+the symbol exists in the global scope. Something like this is enough:
+
+@example
+int plugin_is_GPL_compatible;
+@end example
+
 @subsubheading Data Structures
 
 @table @code
@@ -11185,6 +11203,8 @@ function in a file @file{mk_temp.c}:
 
 #include <gnumake.h>
 
+int plugin_is_GPL_compatible;
+
 char *
 gen_tmpfile(const char *nm, int argc, char **argv)
 @{