create_module.2, delete_module.2, init_module.2, query_module.2: Clarify glibc header file declaration/ABI wrapper details

create_module(), delete_module(), init_module(), and
query_module() are not declared in header files, but
through an accident of history glibc provides an ABI
for them that it continues to maintain, for
compatibility reasons.

Reported-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/create_module.2

@@ -16,8 +16,11 @@ create_module \- create a loadable module entry
 .sp
 .BI "caddr_t create_module(const char *" name ", size_t " size );
 .fi
+
+.IR Note :
+No declaration of this function is provided in glibc headers; see NOTES.
 .SH DESCRIPTION
-.BR Note :
+.IR Note :
 This system call is present only in kernels before Linux 2.6.
 
 .BR create_module ()
@@ -62,6 +65,16 @@ it was removed in Linux 2.6.
 .SH CONFORMING TO
 .BR create_module ()
 is Linux-specific.
+.SH NOTES
+The
+.BR create_module ()
+system call is not suported by glibc.
+No declaration is provided in glibc headers, but,
+through a quirk of history, glibc does export an ABI for this system call.
+Therefore, in order to employ this system call,
+it is sufficient to manually declare the interface in your code;
+alternatively, you can invoke the system call using
+.BR syscall (2).
 .SH SEE ALSO
 .BR delete_module (2),
 .BR init_module (2),

man2/delete_module.2

@@ -31,7 +31,7 @@ delete_module \- unload a kernel module
 .fi
 
 .IR Note :
-There is no glibc wrapper for this system call; see NOTES.
+No declaration of this function is provided in glibc headers; see NOTES.
 .SH DESCRIPTION
 The
 .BR delete_module ()
@@ -173,7 +173,14 @@ was not specified in
 .BR delete_module ()
 is Linux-specific.
 .SH NOTES
-Glibc does not provide a wrapper for this system call; call it using
+The
+.BR delete_module ()
+system call is not suported by glibc.
+No declaration is provided in glibc headers, but,
+through a quirk of history, glibc does export an ABI for this system call.
+Therefore, in order to employ this system call,
+it is sufficient to manually declare the interface in your code;
+alternatively, you can invoke the system call using
 .BR syscall (2).
 
 The uninterruptible sleep that may occur if

man2/init_module.2

@@ -37,7 +37,11 @@ init_module, finit_module \- load a kernel module
 .fi
 
 .IR Note :
-There are no glibc wrappers for these system calls; see NOTES.
+glibc provides no header file declaration of
+.BR init_module ()
+and no wrapper function for
+.BR finit_module ();
+see NOTES.
 .SH DESCRIPTION
 .BR init_module ()
 loads an ELF image into kernel space,
@@ -258,7 +262,19 @@ and
 .BR finit_module ()
 are Linux-specific.
 .SH NOTES
-Glibc does not provide a wrapper for these system calls; call them using
+The
+.BR init_module ()
+system call is not suported by glibc.
+No declaration is provided in glibc headers, but,
+through a quirk of history, glibc does export an ABI for this system call.
+Therefore, in order to employ this system call,
+it is sufficient to manually declare the interface in your code;
+alternatively, you can invoke the system call using
+.BR syscall (2).
+
+Glibc does not provide a wrapper for
+.BR finit_module ();
+call it using
 .BR syscall (2).
 
 Information about currently loaded modules can be found in

man2/query_module.2

@@ -19,9 +19,9 @@ query_module \- query the kernel for various bits pertaining to modules
 .fi
 
 .IR Note :
-There is no glibc wrapper for this system call; see NOTES.
+No declaration of this function is provided in glibc headers; see NOTES.
 .SH DESCRIPTION
-.BR Note :
+.IR Note :
 This system call is present only in kernels before Linux 2.6.
 
 .BR query_module ()
@@ -181,8 +181,14 @@ can be obtained from
 and the files under the directory
 .IR /sys/module .
 
-Glibc does not provide a wrapper for this system call;
-in the unlikely event that you need to use it on an old kernel, use
+The
+.BR query_module ()
+system call is not suported by glibc.
+No declaration is provided in glibc headers, but,
+through a quirk of history, glibc does export an ABI for this system call.
+Therefore, in order to employ this system call,
+it is sufficient to manually declare the interface in your code;
+alternatively, you can invoke the system call using
 .BR syscall (2).
 .SH SEE ALSO
 .BR create_module (2),