kbuild: allow assignment to {A,C}FLAGS_KERNEL on the command line

It is now possible to assign options to AS and CC
on the command line - which is only used for built-in code.

{A,C}FLAGS_KERNEL was used both in the top-level Makefile
in the arch makefiles, thus users had no way to specify
additional options to AS, CC without overriding
the original value.

Introduce a new set of variables KBUILD_{A,C}FLAGS_KERNEL
that is used by arch specific files and free up
{A,C}FLAGS_KERNEL so they can be assigned on
the command line.

All arch Makefiles that used the old variables has been updated.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>

2 files changed, 17 insertions, 2 deletions

diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index d9c655433ec6..e903f20077cf 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -28,10 +28,20 @@ AFLAGS_MODULE
 --------------------------------------------------
 Addtional module specific options to use for $(AS).
 
+AFLAGS_KERNEL
+--------------------------------------------------
+Addtional options for $(AS) when used for assembler
+code for code that is compiled as built-in.
+
 KCFLAGS
 --------------------------------------------------
 Additional options to the C compiler (for built-in and modules).
 
+CFLAGS_KERNEL
+--------------------------------------------------
+Addtional options for $(CC) when used to compile
+code that is compiled as built-in.
+
 CFLAGS_MODULE
 --------------------------------------------------
 Addtional module specific options to use for $(CC).
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 802341abf702..5c878cc6c0b4 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -923,9 +923,9 @@ When kbuild executes, the following steps are followed (roughly):
         The first example utilises the trick that a config option expands
         to 'y' when selected.
 
-    CFLAGS_KERNEL       $(CC) options specific for built-in
+    KBUILD_AFLAGS_KERNEL        $(AS) options specific for built-in
 
-        $(CFLAGS_KERNEL) contains extra C compiler flags used to compile
+        $(KBUILD_AFLAGS_KERNEL) contains extra C compiler flags used to compile
         resident kernel code.
 
     KBUILD_AFLAGS_MODULE   Options for $(AS) when building modules
@@ -934,6 +934,11 @@ When kbuild executes, the following steps are followed (roughly):
         are used for $(AS).
         From commandline AFLAGS_MODULE shall be used (see kbuild.txt).
 
+    KBUILD_CFLAGS_KERNEL        $(CC) options specific for built-in
+
+        $(KBUILD_CFLAGS_KERNEL) contains extra C compiler flags used to compile
+        resident kernel code.
+
     KBUILD_CFLAGS_MODULE   Options for $(CC) when building modules
 
         $(KBUILD_CFLAGS_MODULE) is used to add arch specific options that