Commit d8ecc5cd authored by Sam Ravnborg's avatar Sam Ravnborg Committed by Michal Marek
Browse files

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: default avatarSam Ravnborg <sam@ravnborg.org>
Acked-by: default avatarGuan Xuetao <guanxuetao@mprc.pku.edu.cn>
Tested-by: default avatarGuan Xuetao <guanxuetao@mprc.pku.edu.cn>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Cc: Remis Lima Baima <remis.developer@googlemail.com>
Signed-off-by: default avatarMichal Marek <mmarek@suse.cz>
parent 28bc20dc

.gitignore

+1 −0
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ modules.builtin 
include/config

include/linux/version.h

include/generated

arch/*/include/generated



# stgit generated dirs

patches-*

Documentation/kbuild/makefiles.txt

+36 −0
Original line number Diff line number Diff line
@@ -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

Makefile

+12 −4
Original line number Diff line number Diff line
@@ -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
@@ -417,6 +418,12 @@ 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
@@ -954,7 +961,7 @@ 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
@@ -1028,7 +1035,7 @@ 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
@@ -1143,7 +1150,8 @@ 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

scripts/Makefile.asm-generic

0 → 100644
+23 −0
Original line number Diff line number Diff line 
# 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)

scripts/Makefile.headersinst

+9 −1
Original line number Diff line number Diff line
@@ -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)

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