Commit 052ad274 authored by H. Peter Anvin's avatar H. Peter Anvin
Browse files

kbuild: Add support for an "archheaders" target 



Add support for an "archheaders" target.  This target can generate
files that need to be installed for user space by "make
headers_install" or "make headers_install_all".

In order to support "make headers_install_all", it must be able to run
without the tree having to be configured first.

Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent cb97914b

Documentation/kbuild/makefiles.txt

+32 −18
Original line number Diff line number Diff line
@@ -33,14 +33,15 @@ This document describes the Linux kernel Makefiles. 


	=== 6 Architecture Makefiles

	   --- 6.1 Set variables to tweak the build to the architecture

	   --- 6.2 Add prerequisites to archprepare:

	   --- 6.3 List directories to visit when descending

	   --- 6.4 Architecture-specific boot images

	   --- 6.5 Building non-kbuild targets

	   --- 6.6 Commands useful for building a boot image

	   --- 6.7 Custom kbuild commands

	   --- 6.8 Preprocessing linker scripts

	   --- 6.9 Generic header files

	   --- 6.2 Add prerequisites to archheaders:

	   --- 6.3 Add prerequisites to archprepare:

	   --- 6.4 List directories to visit when descending

	   --- 6.5 Architecture-specific boot images

	   --- 6.6 Building non-kbuild targets

	   --- 6.7 Commands useful for building a boot image

	   --- 6.8 Custom kbuild commands

	   --- 6.9 Preprocessing linker scripts

	   --- 6.10 Generic header files



	=== 7 Kbuild syntax for exported headers

		--- 7.1 header-y
@@ -252,7 +253,7 @@ more details, with real examples. 
	This will create a library lib.a based on delay.o. For kbuild to

	actually recognize that there is a lib.a being built, the directory

	shall be listed in libs-y.

	See also "6.3 List directories to visit when descending".

	See also "6.4 List directories to visit when descending".



	Use of lib-y is normally restricted to lib/ and arch/*/lib.
@@ -974,7 +975,20 @@ When kbuild executes, the following steps are followed (roughly): 
	$(KBUILD_ARFLAGS) set by the top level Makefile to "D" (deterministic

	mode) if this option is supported by $(AR).



--- 6.2 Add prerequisites to archprepare:

--- 6.2 Add prerequisites to archheaders:



	The archheaders: rule is used to generate header files that

	may be installed into user space by "make header_install" or

	"make headers_install_all".  In order to support

	"make headers_install_all", this target has to be able to run

	on an unconfigured tree, or a tree configured for another

	architecture.



	It is run before "make archprepare" when run on the

	architecture itself.





--- 6.3 Add prerequisites to archprepare:



	The archprepare: rule is used to list prerequisites that need to be

	built before starting to descend down in the subdirectories.
@@ -990,7 +1004,7 @@ When kbuild executes, the following steps are followed (roughly): 
	generating offset header files.





--- 6.3 List directories to visit when descending

--- 6.4 List directories to visit when descending



	An arch Makefile cooperates with the top Makefile to define variables

	which specify how to build the vmlinux file.  Note that there is no
@@ -1019,7 +1033,7 @@ When kbuild executes, the following steps are followed (roughly): 
		drivers-$(CONFIG_OPROFILE)  += arch/sparc64/oprofile/





--- 6.4 Architecture-specific boot images

--- 6.5 Architecture-specific boot images



	An arch Makefile specifies goals that take the vmlinux file, compress

	it, wrap it in bootstrapping code, and copy the resulting files
@@ -1070,7 +1084,7 @@ When kbuild executes, the following steps are followed (roughly): 


	When "make" is executed without arguments, bzImage will be built.



--- 6.5 Building non-kbuild targets

--- 6.6 Building non-kbuild targets



    extra-y
@@ -1090,7 +1104,7 @@ When kbuild executes, the following steps are followed (roughly): 
	shall be built, but shall not be linked as part of built-in.o.





--- 6.6 Commands useful for building a boot image

--- 6.7 Commands useful for building a boot image



	Kbuild provides a few macros that are useful when building a

	boot image.
@@ -1112,7 +1126,7 @@ When kbuild executes, the following steps are followed (roughly): 
	always be built.

	Assignments to $(targets) are without $(obj)/ prefix.

	if_changed may be used in conjunction with custom commands as

	defined in 6.7 "Custom kbuild commands".

	defined in 6.8 "Custom kbuild commands".



	Note: It is a typical mistake to forget the FORCE prerequisite.

	Another common pitfall is that whitespace is sometimes
@@ -1171,7 +1185,7 @@ When kbuild executes, the following steps are followed (roughly): 
		$(obj)/%.dtb: $(src)/%.dts

			$(call cmd,dtc)



--- 6.7 Custom kbuild commands

--- 6.8 Custom kbuild commands



	When kbuild is executing with KBUILD_VERBOSE=0, then only a shorthand

	of a command is normally displayed.
@@ -1198,7 +1212,7 @@ When kbuild executes, the following steps are followed (roughly): 
	will be displayed with "make KBUILD_VERBOSE=0".





--- 6.8 Preprocessing linker scripts

--- 6.9 Preprocessing linker scripts



	When the vmlinux image is built, the linker script

	arch/$(ARCH)/kernel/vmlinux.lds is used.
@@ -1228,7 +1242,7 @@ 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

--- 6.10 Generic header files



	The directory include/asm-generic contains the header files

	that may be shared between individual architectures.

Makefile

+6 −3
Original line number Diff line number Diff line
@@ -442,7 +442,7 @@ asm-generic: 


no-dot-config-targets := clean mrproper distclean \

			 cscope gtags TAGS tags help %docs check% coccicheck \

			 include/linux/version.h headers_% \

			 include/linux/version.h headers_% archheaders \

			 kernelversion %src-pkg



config-targets := 0
@@ -979,7 +979,7 @@ prepare1: prepare2 include/linux/version.h include/generated/utsrelease.h \ 
                   include/config/auto.conf

	$(cmd_crmodverdir)



archprepare: prepare1 scripts_basic

archprepare: archheaders prepare1 scripts_basic



prepare0: archprepare FORCE

	$(Q)$(MAKE) $(build)=.
@@ -1046,8 +1046,11 @@ hdr-inst := -rR -f $(srctree)/scripts/Makefile.headersinst obj 
# If we do an all arch process set dst to asm-$(hdr-arch)

hdr-dst = $(if $(KBUILD_HEADERS), dst=include/asm-$(hdr-arch), dst=include/asm)



PHONY += archheaders

archheaders:



PHONY += __headers

__headers: include/linux/version.h scripts_basic asm-generic FORCE

__headers: include/linux/version.h scripts_basic asm-generic archheaders FORCE

	$(Q)$(MAKE) $(build)=scripts build_unifdef



PHONY += headers_install_all

scripts/headers.sh

+1 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ set -e 
do_command()

{

	if [ -f ${srctree}/arch/$2/include/asm/Kbuild ]; then

		make ARCH=$2 KBUILD_HEADERS=$1 archheaders

		make ARCH=$2 KBUILD_HEADERS=$1 headers_$1

	else

		printf "Ignoring arch: %s\n" ${arch}

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