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| author | Sam Ravnborg <sam@ravnborg.org> | 2011-04-27 22:29:49 +0200 |
|---|---|---|
| committer | Michal Marek <mmarek@suse.cz> | 2011-04-28 18:01:41 +0200 |
| commit | d8ecc5cd8e227bc318513b5306ae88a474b8886d (patch) | |
| tree | f05fe662c000b8219923b8c464c9c186b599190e /Documentation/kbuild | |
| parent | 28bc20dccadc610c56e27255aeef2938141a0cd3 (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/kbuild')
| -rw-r--r-- | Documentation/kbuild/makefiles.txt | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 40e082bb8c5..835b64acf0b 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 |