kbuild: asm-generic support
There is an increasing amount of header files
shared between individual architectures in asm-generic.
To avoid a lot of dummy wrapper files that just
include the corresponding file in asm-generic provide
some basic support in kbuild for this.
With the following patch an architecture can maintain
a list of files in the file arch/$(ARCH)/include/asm/Kbuild
To use a generic file just add:
generic-y += <name-of-header-file.h>
For each file listed kbuild will generate the necessary
wrapper in arch/$(ARCH)/include/generated/asm.
When installing userspace headers a wrapper is likewise created.
The original inspiration for this came from the unicore32
patchset - although a different method is used.
The patch includes several improvements from Arnd Bergmann.
Michael Marek contributed Makefile.asm-generic.
Remis Baima did an intial implementation along to achive
the same - see https://patchwork.kernel.org/patch/13352/
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Guan Xuetao <guanxuetao@mprc.pku.edu.cn>
Tested-by: Guan Xuetao <guanxuetao@mprc.pku.edu.cn>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Remis Lima Baima <remis.developer@googlemail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 40e082b..835b64a 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -40,11 +40,13 @@
--- 6.6 Commands useful for building a boot image
--- 6.7 Custom kbuild commands
--- 6.8 Preprocessing linker scripts
+ --- 6.9 Generic header files
=== 7 Kbuild syntax for exported headers
--- 7.1 header-y
--- 7.2 objhdr-y
--- 7.3 destination-y
+ --- 7.4 generic-y
=== 8 Kbuild Variables
=== 9 Makefile language
@@ -1214,6 +1216,14 @@
The kbuild infrastructure for *lds file are used in several
architecture-specific files.
+--- 6.9 Generic header files
+
+ The directory include/asm-generic contains the header files
+ that may be shared between individual architectures.
+ The recommended approach how to use a generic header file is
+ to list the file in the Kbuild file.
+ See "7.4 generic-y" for further info on syntax etc.
+
=== 7 Kbuild syntax for exported headers
The kernel include a set of headers that is exported to userspace.
@@ -1270,6 +1280,32 @@
In the example above all exported headers in the Kbuild file
will be located in the directory "include/linux" when exported.
+ --- 7.4 generic-y
+
+ If an architecture uses a verbatim copy of a header from
+ include/asm-generic then this is listed in the file
+ arch/$(ARCH)/include/asm/Kbuild like this:
+
+ Example:
+ #arch/x86/include/asm/Kbuild
+ generic-y += termios.h
+ generic-y += rtc.h
+
+ During the prepare phase of the build a wrapper include
+ file is generated in the directory:
+
+ arch/$(ARCH)/include/generated/asm
+
+ When a header is exported where the architecture uses
+ the generic header a similar wrapper is generated as part
+ of the set of exported headers in the directory:
+
+ usr/include/asm
+
+ The generated wrapper will in both cases look like the following:
+
+ Example: termios.h
+ #include <asm-generic/termios.h>
=== 8 Kbuild Variables
