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    Subject[PATCH v4] kbuild: asm-generic support
    From 8546953f0c87d6b1c37c25df73511780c86ad89d Mon Sep 17 00:00:00 2001
    From: Sam Ravnborg <sam@ravnborg.org>
    Date: Fri, 22 Apr 2011 14:45:13 +0200
    Subject: [PATCH] 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.

    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>
    Cc: Arnd Bergmann <arnd@arndb.de>
    ---

    Changes v3 => v4
    Addressed feedback from Guan:
    - drop empty lines
    - fix line-too-long
    - add his Tested-by, Acked-by tags

    Sam


    .gitignore | 1 +
    Documentation/kbuild/makefiles.txt | 36 ++++++++++++++++++++++++++++++++++++
    Makefile | 16 ++++++++++++----
    scripts/Makefile.asm-generic | 23 +++++++++++++++++++++++
    scripts/Makefile.headersinst | 10 +++++++++-
    5 files changed, 81 insertions(+), 5 deletions(-)
    create mode 100644 scripts/Makefile.asm-generic

    diff --git a/.gitignore b/.gitignore
    index 5d56a3f..9dacde0 100644
    --- a/.gitignore
    +++ b/.gitignore
    @@ -57,6 +57,7 @@ modules.builtin
    include/config
    include/linux/version.h
    include/generated
    +arch/*/include/generated

    # stgit generated dirs
    patches-*
    diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
    index 5d145bb..7f2b8e7 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
    @@ -1209,6 +1211,14 @@ 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.
    @@ -1265,6 +1275,32 @@ 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

    diff --git a/Makefile b/Makefile
    index b967b96..9c67453 100644
    --- a/Makefile
    +++ b/Makefile
    @@ -349,7 +349,8 @@ CFLAGS_GCOV = -fprofile-arcs -ftest-coverage

    # Use LINUXINCLUDE when you must reference the include/ directory.
    # Needed to be compatible with the O= option
    -LINUXINCLUDE := -I$(srctree)/arch/$(hdr-arch)/include -Iinclude \
    +LINUXINCLUDE := -I$(srctree)/arch/$(hdr-arch)/include \
    + -Iarch/$(hdr-arch)/include/generated -Iinclude \
    $(if $(KBUILD_SRC), -I$(srctree)/include) \
    -include include/generated/autoconf.h

    @@ -416,6 +417,12 @@ ifneq ($(KBUILD_SRC),)
    $(srctree) $(objtree) $(VERSION) $(PATCHLEVEL)
    endif

    +# Support for using generic headers in asm-generic
    +PHONY += asm-generic
    +asm-generic:
    + $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.asm-generic \
    + obj=arch/$(SRCARCH)/include/generated/asm
    +
    # To make sure we do not include .config for any of the *config targets
    # catch them early, and hand them over to scripts/kconfig/Makefile
    # It is allowed to specify more targets when calling make, including
    @@ -947,7 +954,7 @@ ifneq ($(KBUILD_SRC),)
    endif

    # prepare2 creates a makefile if using a separate output directory
    -prepare2: prepare3 outputmakefile
    +prepare2: prepare3 outputmakefile asm-generic

    prepare1: prepare2 include/linux/version.h include/generated/utsrelease.h \
    include/config/auto.conf
    @@ -1021,7 +1028,7 @@ hdr-inst := -rR -f $(srctree)/scripts/Makefile.headersinst obj
    hdr-dst = $(if $(KBUILD_HEADERS), dst=include/asm-$(hdr-arch), dst=include/asm)

    PHONY += __headers
    -__headers: include/linux/version.h scripts_basic FORCE
    +__headers: include/linux/version.h scripts_basic asm-generic FORCE
    $(Q)$(MAKE) $(build)=scripts build_unifdef

    PHONY += headers_install_all
    @@ -1136,7 +1143,8 @@ CLEAN_FILES += vmlinux System.map \
    .tmp_kallsyms* .tmp_version .tmp_vmlinux* .tmp_System.map

    # Directories & files removed with 'make mrproper'
    -MRPROPER_DIRS += include/config usr/include include/generated
    +MRPROPER_DIRS += include/config usr/include include/generated \
    + arch/*/include/generated
    MRPROPER_FILES += .config .config.old .version .old_version \
    include/linux/version.h \
    Module.symvers tags TAGS cscope* GPATH GTAGS GRTAGS GSYMS
    diff --git a/scripts/Makefile.asm-generic b/scripts/Makefile.asm-generic
    new file mode 100644
    index 0000000..a687cb6
    --- /dev/null
    +++ b/scripts/Makefile.asm-generic
    @@ -0,0 +1,23 @@
    +# include/asm-generic contains a lot of files that are used
    +# verbatim by several architectures.
    +#
    +# This Makefile reads the file arch/$(SRCARCH)/include/asm/Kbuild
    +# and for each file listed in this file with generic-y creates
    +# a small wrapper file in $(obj) (arch/$(SRCARCH)/include/generated/asm)
    +
    +kbuild-file := $(srctree)/arch/$(SRCARCH)/include/asm/Kbuild
    +include $(kbuild-file)
    +
    +include scripts/Kbuild.include
    +
    +# Create output directory if not already present
    +_dummy := $(shell [ -d $(obj) ] || mkdir -p $(obj))
    +
    +quiet_cmd_wrap = WRAP $@
    +cmd_wrap = echo "\#include <asm-generic/$*.h>" >$@
    +
    +all: $(patsubst %, $(obj)/%, $(generic-y))
    +
    +$(obj)/%.h:
    + $(call cmd,wrap)
    +
    diff --git a/scripts/Makefile.headersinst b/scripts/Makefile.headersinst
    index f89cb87..a57f5bd 100644
    --- a/scripts/Makefile.headersinst
    +++ b/scripts/Makefile.headersinst
    @@ -27,8 +27,13 @@ header-y := $(filter-out %/, $(header-y))
    install-file := $(install)/.install
    check-file := $(install)/.check

    +# generic-y list all files an architecture uses from asm-generic
    +# Use this to build a list of headers which require a wrapper
    +wrapper-files := $(filter $(header-y), $(generic-y))
    +
    # all headers files for this dir
    -all-files := $(header-y) $(objhdr-y)
    +header-y := $(filter-out $(generic-y), $(header-y))
    +all-files := $(header-y) $(objhdr-y) $(wrapper-files)
    input-files := $(addprefix $(srctree)/$(obj)/,$(header-y)) \
    $(addprefix $(objtree)/$(obj)/,$(objhdr-y))
    output-files := $(addprefix $(install)/, $(all-files))
    @@ -47,6 +52,9 @@ quiet_cmd_install = INSTALL $(printdir) ($(words $(all-files))\
    cmd_install = \
    $(PERL) $< $(srctree)/$(obj) $(install) $(SRCARCH) $(header-y); \
    $(PERL) $< $(objtree)/$(obj) $(install) $(SRCARCH) $(objhdr-y); \
    + for F in $(wrapper-files); do \
    + echo "\#include <asm-generic/$$F>" > $(install)/$$F; \
    + done; \
    touch $@

    quiet_cmd_remove = REMOVE $(unwanted)
    --
    1.6.0.6


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