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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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