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: Masahiro Yamada <masahiroy@kernel.org>

Author: masahir0y

Documentation/kbuild/makefiles.rst

@@ -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
 
@@ -710,55 +709,39 @@ 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 ) < $<
 
 	The target $(obj)/devlist.h will not be built before
 	$(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

@@ -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) $<