RE: [PATCH 1/2] kbuild: asm-generic support

[Guan Xuetao]

Sam:
There is a big problem in previous patch set.
When re-compile kernel image, almost all source files will be re-compiled since
arch/*/include/generated/asm/* being re-created.
So I add a judgment before auto-generation, as following:

commit 03e63f75b37a4d6e5668bc07ae385a174efd6e8c
Author: GuanXuetao <gxt@xxxxxxxxxxxxxxx>
Date:   Sun Jan 9 22:35:24 2011 +0800

    unicore32: adjust auto-generated asm-generic headers method
    	solve the problem:
    		former method will re-generate headers each compile processing
    	attention for new method:
    		when add new auto-generated asm-generic header
    		"make mrproper" is needed first

diff --git a/arch/unicore32/Makefile b/arch/unicore32/Makefile
index 0be046d..de1ce7d 100644
--- a/arch/unicore32/Makefile
+++ b/arch/unicore32/Makefile
@@ -76,11 +76,13 @@ ASM_GENERIC_HEADERS	+= ucontext.h unaligned.h user.h
 ASM_GENERIC_HEADERS	+= vga.h
 ASM_GENERIC_HEADERS	+= xor.h
 
-%.h:
+archprepare:
+ifneq ($(ASM_GENERATED_DIR), $(wildcard $(ASM_GENERATED_DIR)))
 	$(Q)mkdir -p $(ASM_GENERATED_DIR)/asm
-	$(Q)echo '#include <asm-generic/$(notdir $@)>' > $(ASM_GENERATED_DIR)/asm/$@
-
-archprepare: $(ASM_GENERIC_HEADERS)
+	$(Q)$(foreach a, $(ASM_GENERIC_HEADERS),	\
+		echo '#include <asm-generic/$a>'	\
+			> $(ASM_GENERATED_DIR)/asm/$a; )
+endif
 
 boot			:= arch/unicore32/boot

> -----Original Message-----
> From: Sam Ravnborg [mailto:sam@xxxxxxxxxxxx]
> Sent: Monday, January 10, 2011 3:29 AM
> To: lkml; linux-kbuild; linux arch; Arnd Bergmann; Guan Xuetao; Michal Marek
> Subject: [PATCH 1/2] kbuild: asm-generic support
> 
> >From 1c33973f2e4a099eadfb1a37cd3a28a3c8d3202f Mon Sep 17 00:00:00 2001
> From: Sam Ravnborg <sam@xxxxxxxxxxxx>
> Date: Sun, 9 Jan 2011 19:45:40 +0100
> Subject: [PATCH 1/2] 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 is used a different method.
> 
> The patch includes several improvements from Arnd Bergmann.
> 
> Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
> Cc: Guan Xuetao <guanxuetao@xxxxxxxxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> ---
>  .gitignore                         |    1 +
>  Documentation/kbuild/makefiles.txt |   36 ++++++++++++++++++++++++++++++++++++
>  Makefile                           |   15 +++++++++++----
>  scripts/Makefile.headersinst       |   18 +++++++++++++++---
>  scripts/asm-generic.sh             |   33 +++++++++++++++++++++++++++++++++
>  5 files changed, 96 insertions(+), 7 deletions(-)
>  create mode 100644 scripts/asm-generic.sh
> 
> diff --git a/.gitignore b/.gitignore
> index 8faa6c0..e3cfd57 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -56,6 +56,7 @@ 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 0ef00bd..bc79a3d 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
> @@ -1194,6 +1196,14 @@ 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.
> @@ -1250,6 +1260,32 @@ 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 74b2555..263eb65 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -344,7 +344,8 @@ 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
> 
> @@ -411,6 +412,11 @@ ifneq ($(KBUILD_SRC),)
>  	    $(srctree) $(objtree) $(VERSION) $(PATCHLEVEL)
>  endif
> 
> +# Support for using generic headers in asm-generic
> +PHONY += asm-generic
> +asm-generic:
> +	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/asm-generic.sh $(SRCARCH)
> +
>  # To make sure we do not include .config for any of the *config targets
>  # catch them early, and hand them over to scripts/kconfig/Makefile
>  # It is allowed to specify more targets when calling make, including
> @@ -942,7 +948,7 @@ ifneq ($(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
> @@ -1016,7 +1022,7 @@ 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 scripts/unifdef
> 
>  PHONY += headers_install_all
> @@ -1131,7 +1137,8 @@ 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*
> diff --git a/scripts/Makefile.headersinst b/scripts/Makefile.headersinst
> index f89cb87..7960b19 100644
> --- a/scripts/Makefile.headersinst
> +++ b/scripts/Makefile.headersinst
> @@ -14,6 +14,7 @@ kbuild-file := $(srctree)/$(obj)/Kbuild
>  include $(kbuild-file)
> 
>  _dst := $(if $(destination-y),$(destination-y),$(_dst))
> +_src := $(srctree)/$(obj)
> 
>  include scripts/Kbuild.include
> 
> @@ -27,10 +28,16 @@ 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)
> -input-files   := $(addprefix $(srctree)/$(obj)/,$(header-y)) \
> +header-y      := $(filter-out $(generic-y), $(header-y))
> +all-files     := $(header-y) $(objhdr-y) $(wrapper-files)
> +input-files   := $(addprefix $(_src)/,$(header-y)) \
>                   $(addprefix $(objtree)/$(obj)/,$(objhdr-y))
> +
>  output-files  := $(addprefix $(install)/, $(all-files))
> 
>  # Work out what needs to be removed
> @@ -47,8 +54,12 @@ 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)
>        cmd_remove = rm -f $(unwanted-file)
> 
> @@ -69,7 +80,8 @@ __headersinst: $(subdirs) $(install-file)
>  	@:
> 
>  targets += $(install-file)
> -$(install-file): scripts/headers_install.pl $(input-files) FORCE
> +$(install-file): scripts/headers_install.pl \
> +                 $(input-files) FORCE
>  	$(if $(unwanted),$(call cmd,remove),)
>  	$(if $(wildcard $(dir $@)),,$(shell mkdir -p $(dir $@)))
>  	$(call if_changed,install)
> diff --git a/scripts/asm-generic.sh b/scripts/asm-generic.sh
> new file mode 100644
> index 0000000..d28127f
> --- /dev/null
> +++ b/scripts/asm-generic.sh
> @@ -0,0 +1,33 @@
> +#!/bin/sh
> +#
> +# include/asm-generic contains a lot of files that are used
> +# verbatim by several architectures.
> +#
> +# This scripts read the file arch/$(ARCH)/include/asm/Kbuild
> +# and for each file listed in this file with generic-y create
> +# a small wrapper file in arch/$(ARCH)/include/generated/
> +
> +# read list of header files form Kbuild
> +# The file has make syntax which looks like this:
> +#
> +# generic-y += <filename>
> +
> +srcdir=${srctree}/arch/$1/include/asm
> +gendir=arch/$1/include/generated/asm
> +
> +# Read the list of files (note that the list uses make syntax)
> +files=$( cat ${srcdir}/Kbuild | \
> +          grep -v ^# | grep generic-y | cut -d '=' -f 2)
> +
> +mkdir -p ${gendir}
> +
> +# create include files for each file used form asm-generic
> +for F in ${files}; do
> +	if [ -f ${srcdir}/$F ]; then
> +		echo "ERROR: ${srcdir}/$F exists"
> +		echo "$F is also listed as generic-y in ${srcdir}/Kbuild"
> +		echo "Did you forget to remove the file?"
> +		exit 1
> +	fi
> +	echo "#include <asm-generic/$F>" > ${gendir}/$F
> +done
> --
> 1.6.0.6

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