path: root/Documentation
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authorSam Ravnborg <sam@ravnborg.org>2011-04-27 22:29:49 +0200
committerMichal Marek <mmarek@suse.cz>2011-04-28 18:01:41 +0200
commitd8ecc5cd8e227bc318513b5306ae88a474b8886d (patch)
treef05fe662c000b8219923b8c464c9c186b599190e /Documentation
parentkbuild: implement several W= levels (diff)
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>
Diffstat (limited to 'Documentation')
1 files changed, 36 insertions, 0 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 40e082bb8c52..835b64acf0b4 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -40,11 +40,13 @@ This document describes the Linux kernel Makefiles.
--- 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 @@ When kbuild executes, the following steps are followed (roughly):
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 @@ See subsequent chapter for the syntax of the Kbuild file.
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