kbuild, x86: Track generated headers with generated-y

Track generated header files which aren't already in genhdr-y, alongside
generic-y wrappers in the */include/generated/[uapi/]asm/ directories.
Currently only x86 generates extra headers in these directories, for the
purposes of enumerating system calls for different ABIs, and xen
hypercalls.

This will allow the asm-generic wrapper handling code to remove stale
wrappers when files are removed from generic-y, without also removing
these headers which are generated separately.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-kbuild@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: Michal Marek <mmarek@suse.com>
Link: http://lkml.kernel.org/r/1466808144-23209-2-git-send-email-james.hogan@imgtec.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 14 insertions, 0 deletions

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 13f888a02a3d..385a5ef41c17 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -47,6 +47,7 @@ This document describes the Linux kernel Makefiles.
                 --- 7.2 genhdr-y
                 --- 7.3 destination-y
                 --- 7.4 generic-y
+                --- 7.5 generated-y
 
         === 8 Kbuild Variables
         === 9 Makefile language
@@ -1319,6 +1320,19 @@ See subsequent chapter for the syntax of the Kbuild file.
                 Example: termios.h
                         #include <asm-generic/termios.h>
 
+        --- 7.5 generated-y
+
+        If an architecture generates other header files alongside generic-y
+        wrappers, and not included in genhdr-y, then generated-y specifies
+        them.
+
+        This prevents them being treated as stale asm-generic wrappers and
+        removed.
+
+                Example:
+                        #arch/x86/include/asm/Kbuild
+                        generated-y += syscalls_32.h
+
 === 8 Kbuild Variables
 
 The top Makefile exports the following variables: