kbuild: introduce ld-option

ld-option is used to check if $(LD) supports a specific option.

Based on patch from Andi Kleen.

Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
First use is to check if option -X is supported (upcoming patch).
Theis is ne

1 files changed, 14 insertions, 0 deletions

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 7847fce13bd6..71c602d61680 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -18,6 +18,7 @@ This document describes the Linux kernel Makefiles.
            --- 3.9 Dependency tracking
            --- 3.10 Special Rules
            --- 3.11 $(CC) support functions
+           --- 3.12 $(LD) support functions
 
         === 4 Host Program support
            --- 4.1 Simple Host Program
@@ -570,6 +571,19 @@ more details, with real examples.
                         endif
                 endif
 
+--- 3.12 $(LD) support functions
+
+    ld-option
+        ld-option is used to check if $(LD) supports the supplied option.
+        ld-option takes two options as arguments.
+        The second argument is an optional option that can be used if the
+        first option is not supported by $(LD).
+
+        Example:
+                #Makefile
+                LDFLAGS_vmlinux += $(call really-ld-option, -X)
+
+
 === 4 Host Program support
 
 Kbuild supports building executables on the host for use during the