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

It is now possible to assign options to AS, CC and LD
on the command line - which is only used when building modules.

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

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

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

Note: Previously we had a MODFLAGS variable for both
AS and CC. But in favour of consistency this was dropped.
So in some cases arch Makefile has one assignmnet replaced by
two assignmnets.

Note2: MODFLAGS was not documented and is dropped
without any notice. I do not expect much/any breakage
from this.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Chen Liqin <liqin.chen@sunplusct.com>
Acked-by: Mike Frysinger <vapier@gentoo.org> [blackfin]
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> [avr32]
Signed-off-by: Michal Marek <mmarek@suse.cz>

2 files changed, 29 insertions, 5 deletions

diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index 634c625da8ce..d9c655433ec6 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -22,11 +22,23 @@ building C files and assembler files.
 
 KAFLAGS
 --------------------------------------------------
-Additional options to the assembler.
+Additional options to the assembler (for built-in and modules).
+
+AFLAGS_MODULE
+--------------------------------------------------
+Addtional module specific options to use for $(AS).
 
 KCFLAGS
 --------------------------------------------------
-Additional options to the C compiler.
+Additional options to the C compiler (for built-in and modules).
+
+CFLAGS_MODULE
+--------------------------------------------------
+Addtional module specific options to use for $(CC).
+
+LDFLAGS_MODULE
+--------------------------------------------------
+Additional options used for $(LD) when linking modules.
 
 KBUILD_VERBOSE
 --------------------------------------------------
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 71c602d61680..802341abf702 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -928,11 +928,23 @@ When kbuild executes, the following steps are followed (roughly):
         $(CFLAGS_KERNEL) contains extra C compiler flags used to compile
         resident kernel code.
 
-    CFLAGS_MODULE       $(CC) options specific for modules
+    KBUILD_AFLAGS_MODULE   Options for $(AS) when building modules
 
-        $(CFLAGS_MODULE) contains extra C compiler flags used to compile code
-        for loadable kernel modules.
+        $(KBUILD_AFLAGS_MODULE) is used to add arch specific options that
+        are used for $(AS).
+        From commandline AFLAGS_MODULE shall be used (see kbuild.txt).
 
+    KBUILD_CFLAGS_MODULE   Options for $(CC) when building modules
+
+        $(KBUILD_CFLAGS_MODULE) is used to add arch specific options that
+        are used for $(CC).
+        From commandline CFLAGS_MODULE shall be used (see kbuild.txt).
+
+    KBUILD_LDFLAGS_MODULE   Options for $(LD) when linking modules
+
+        $(KBUILD_LDFLAGS_MODULE) is used to add arch specific options
+        used when linking modules. This is often a linker script.
+        From commandline LDFLAGS_MODULE shall be used (see kbuild.txt).
 
 --- 6.2 Add prerequisites to archprepare: