Commit 5f2fb52f authored by Masahiro Yamada's avatar Masahiro Yamada
Browse files

kbuild: rename hostprogs-y/always to hostprogs/always-y 



In old days, the "host-progs" syntax was used for specifying host
programs. It was renamed to the current "hostprogs-y" in 2004.

It is typically useful in scripts/Makefile because it allows Kbuild to
selectively compile host programs based on the kernel configuration.

This commit renames like follows:

  always       ->  always-y
  hostprogs-y  ->  hostprogs

So, scripts/Makefile will look like this:

  always-$(CONFIG_BUILD_BIN2C) += ...
  always-$(CONFIG_KALLSYMS)    += ...
      ...
  hostprogs := $(always-y) $(always-m)

I think this makes more sense because a host program is always a host
program, irrespective of the kernel configuration. We want to specify
which ones to compile by CONFIG options, so always-y will be handier.

The "always", "hostprogs-y", "hostprogs-m" will be kept for backward
compatibility for a while.

Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
parent faa7bdd7

Documentation/kbuild/makefiles.rst

+16 −33
Original line number Diff line number Diff line
@@ -28,7 +28,6 @@ This document describes the Linux kernel Makefiles. 
	   --- 4.3 Using C++ for host programs

	   --- 4.4 Controlling compiler options for host programs

	   --- 4.5 When host programs are actually built

	   --- 4.6 Using hostprogs-$(CONFIG_FOO)



	=== 5 Kbuild clean infrastructure
@@ -595,11 +594,11 @@ compilation stage. 
Two steps are required in order to use a host executable.



The first step is to tell kbuild that a host program exists. This is

done utilising the variable hostprogs-y.

done utilising the variable "hostprogs".



The second step is to add an explicit dependency to the executable.

This can be done in two ways. Either add the dependency in a rule,

or utilise the variable $(always).

or utilise the variable "always-y".

Both possibilities are described in the following.



4.1 Simple Host Program
@@ -612,7 +611,7 @@ Both possibilities are described in the following. 


	Example::



		hostprogs-y := bin2hex

		hostprogs := bin2hex



	Kbuild assumes in the above example that bin2hex is made from a single

	c-source file named bin2hex.c located in the same directory as
@@ -630,7 +629,7 @@ Both possibilities are described in the following. 
	Example::



		#scripts/lxdialog/Makefile

		hostprogs-y   := lxdialog

		hostprogs     := lxdialog

		lxdialog-objs := checklist.o lxdialog.o



	Objects with extension .o are compiled from the corresponding .c
@@ -650,7 +649,7 @@ Both possibilities are described in the following. 
	Example::



		#scripts/kconfig/Makefile

		hostprogs-y   := qconf

		hostprogs     := qconf

		qconf-cxxobjs := qconf.o



	In the example above the executable is composed of the C++ file
@@ -662,7 +661,7 @@ Both possibilities are described in the following. 
	Example::



		#scripts/kconfig/Makefile

		hostprogs-y   := qconf

		hostprogs     := qconf

		qconf-cxxobjs := qconf.o

		qconf-objs    := check.o
@@ -710,7 +709,7 @@ Both possibilities are described in the following. 
	Example::



		#drivers/pci/Makefile

		hostprogs-y := gen-devlist

		hostprogs := gen-devlist

		$(obj)/devlist.h: $(src)/pci.ids $(obj)/gen-devlist

			( cd $(obj); ./gen-devlist ) < $<
@@ -718,47 +717,31 @@ Both possibilities are described in the following. 
	$(obj)/gen-devlist is updated. Note that references to

	the host programs in special rules must be prefixed with $(obj).



	(2) Use $(always)

	(2) Use always-y



	When there is no suitable special rule, and the host program

	shall be built when a makefile is entered, the $(always)

	shall be built when a makefile is entered, the always-y

	variable shall be used.



	Example::



		#scripts/lxdialog/Makefile

		hostprogs-y   := lxdialog

		always        := $(hostprogs-y)

		hostprogs     := lxdialog

		always-y      := $(hostprogs)



	This will tell kbuild to build lxdialog even if not referenced in

	any rule.



4.6 Using hostprogs-$(CONFIG_FOO)

---------------------------------



	A typical pattern in a Kbuild file looks like this:



	Example::



		#scripts/Makefile

		hostprogs-$(CONFIG_KALLSYMS) += kallsyms



	Kbuild knows about both 'y' for built-in and 'm' for module.

	So if a config symbol evaluates to 'm', kbuild will still build

	the binary. In other words, Kbuild handles hostprogs-m exactly

	like hostprogs-y. But only hostprogs-y is recommended to be used

	when no CONFIG symbols are involved.



5 Kbuild clean infrastructure

=============================



"make clean" deletes most generated files in the obj tree where the kernel

is compiled. This includes generated files such as host programs.

Kbuild knows targets listed in $(hostprogs-y), $(hostprogs-m), $(always),

$(extra-y) and $(targets). They are all deleted during "make clean".

Files matching the patterns "*.[oas]", "*.ko", plus some additional files

generated by kbuild are deleted all over the kernel src tree when

"make clean" is executed.

Kbuild knows targets listed in $(hostprogs), $(always-y), $(always-m),

$(always-), $(extra-y), $(extra-) and $(targets). They are all deleted

during "make clean". Files matching the patterns "*.[oas]", "*.ko", plus

some additional files generated by kbuild are deleted all over the kernel

source tree when "make clean" is executed.



Additional files or directories can be specified in kbuild makefiles by use of

$(clean-files).

Kbuild

+4 −4
Original line number Diff line number Diff line
@@ -7,7 +7,7 @@ 


bounds-file := include/generated/bounds.h



always  := $(bounds-file)

always-y := $(bounds-file)

targets := kernel/bounds.s



$(bounds-file): kernel/bounds.s FORCE
@@ -28,7 +28,7 @@ $(timeconst-file): kernel/time/timeconst.bc FORCE 


offsets-file := include/generated/asm-offsets.h



always  += $(offsets-file)

always-y += $(offsets-file)

targets += arch/$(SRCARCH)/kernel/asm-offsets.s



arch/$(SRCARCH)/kernel/asm-offsets.s: $(timeconst-file) $(bounds-file)
@@ -39,7 +39,7 @@ $(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE 
#####

# Check for missing system calls



always += missing-syscalls

always-y += missing-syscalls



quiet_cmd_syscalls = CALL    $<

      cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags) $(missing_syscalls_flags)
@@ -50,7 +50,7 @@ missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE 
#####

# Check atomic headers are up-to-date



always += old-atomics

always-y += old-atomics



quiet_cmd_atomics = CALL    $<

      cmd_atomics = $(CONFIG_SHELL) $<

arch/alpha/boot/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -8,7 +8,7 @@ 
# Copyright (C) 1994 by Linus Torvalds

#



hostprogs-y	:= tools/mkbb tools/objstrip

hostprogs	:= tools/mkbb tools/objstrip

targets		:= vmlinux.gz vmlinux \

		   vmlinux.nh tools/lxboot tools/bootlx tools/bootph \

		   tools/bootpzh bootloader bootpheader bootpzheader

arch/arm/vdso/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -5,7 +5,7 @@ 
ARCH_REL_TYPE_ABS := R_ARM_JUMP_SLOT|R_ARM_GLOB_DAT|R_ARM_ABS32

include $(srctree)/lib/vdso/Makefile



hostprogs-y := vdsomunge

hostprogs := vdsomunge



obj-vdso := vgettimeofday.o datapage.o note.o

arch/arm64/kernel/vdso32/Makefile

+2 −2
Original line number Diff line number Diff line
@@ -115,9 +115,9 @@ VDSO_LDFLAGS += $(call cc32-ldoption,-fuse-ld=bfd) 


# Borrow vdsomunge.c from the arm vDSO

# We have to use a relative path because scripts/Makefile.host prefixes

# $(hostprogs-y) with $(obj)

# $(hostprogs) with $(obj)

munge := ../../../arm/vdso/vdsomunge

hostprogs-y := $(munge)

hostprogs := $(munge)



c-obj-vdso := note.o

c-obj-vdso-gettimeofday := vgettimeofday.o

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