kbuild: enable 'make AFLAGS=...' to add additional options to AS

The variable AFLAGS is a wellknown variable and the usage by
kbuild may result in unexpected behaviour.
On top of that several people over time has asked for a way to
pass in additional flags to gcc.

This patch replace use of AFLAGS with KBUILD_AFLAGS all over
the tree.

Patch was tested on following architectures:
alpha, arm, i386, x86_64, mips, sparc, sparc64, ia64, m68k, s390

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 1ca535bcc8c7..f4779cd1542f 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -424,6 +424,7 @@ more details, with real examples.
         as-instr checks if the assembler reports a specific instruction
         and then outputs either option1 or option2
         C escapes are supported in the test instruction
+        Note: as-instr-option uses KBUILD_AFLAGS for $(AS) options
 
     cc-option
         cc-option is used to check if $(CC) supports a given option, and not
@@ -819,14 +820,14 @@ When kbuild executes, the following steps are followed (roughly):
         In this example, the binary $(obj)/image is a binary version of
         vmlinux. The usage of $(call if_changed,xxx) will be described later.
 
-    AFLAGS              $(AS) assembler flags
+    KBUILD_AFLAGS               $(AS) assembler flags
 
         Default value - see top level Makefile
         Append or modify as required per architecture.
 
         Example:
                 #arch/sparc64/Makefile
-                AFLAGS += -m64 -mcpu=ultrasparc
+                KBUILD_AFLAGS += -m64 -mcpu=ultrasparc
 
     KBUILD_CFLAGS               $(CC) compiler flags