Commit ffd602eb authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'kbuild-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild 

Pull Kbuild updates from Masahiro Yamada:

 - do not generate unneeded top-level built-in.a

 - let git ignore O= directory entirely

 - optimize scripts/kallsyms slightly

 - exclude DWARF info from *.s regardless of config options

 - fix GCC toolchain search path for Clang to prepare ld.lld support

 - do not generate modules.order when CONFIG_MODULES is disabled

 - simplify single target rules and remove VPATH for external module
   build

 - allow to add optional flags to dpkg-buildpackage when building
   deb-pkg

 - move some compiler option tests from Makefile to Kconfig

 - various Makefile cleanups

* tag 'kbuild-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (40 commits)
  kbuild: remove scripts/basic/% build target
  kbuild: use -Werror=implicit-... instead of -Werror-implicit-...
  kbuild: clean up scripts/gcc-version.sh
  kbuild: remove cc-version macro
  kbuild: update comment block of scripts/clang-version.sh
  kbuild: remove commented-out INITRD_COMPRESS
  kbuild: move -gsplit-dwarf, -gdwarf-4 option tests to Kconfig
  kbuild: [bin]deb-pkg: add DPKG_FLAGS variable
  kbuild: move ".config not found!" message from Kconfig to Makefile
  kbuild: invoke syncconfig if include/config/auto.conf.cmd is missing
  kbuild: simplify single target rules
  kbuild: remove empty rules for makefiles
  kbuild: make -r/-R effective in top Makefile for old Make versions
  kbuild: move tools_silent to a more relevant place
  kbuild: compute false-positive -Wmaybe-uninitialized cases in Kconfig
  kbuild: refactor cc-cross-prefix implementation
  kbuild: hardcode genksyms path and remove GENKSYMS variable
  scripts/gdb: refactor rules for symlink creation
  kbuild: create symlink to vmlinux-gdb.py in scripts_gdb target
  scripts/gdb: do not descend into scripts/gdb from scripts
  ...
parents 5af7f115 9250d20e

Documentation/devicetree/bindings/Makefile

+1 −1
Original line number Original line Diff line number Diff line
@@ -15,7 +15,7 @@ DT_TMP_SCHEMA := processed-schema.yaml 
extra-y += $(DT_TMP_SCHEMA)

extra-y += $(DT_TMP_SCHEMA)





quiet_cmd_mk_schema = SCHEMA  $@

quiet_cmd_mk_schema = SCHEMA  $@

      cmd_mk_schema = $(DT_MK_SCHEMA) $(DT_MK_SCHEMA_FLAGS) -o $@ $(filter-out FORCE, $^)

      cmd_mk_schema = $(DT_MK_SCHEMA) $(DT_MK_SCHEMA_FLAGS) -o $@ $(real-prereqs)





DT_DOCS = $(shell \

DT_DOCS = $(shell \

	cd $(srctree)/$(src) && \

	cd $(srctree)/$(src) && \

Documentation/kbuild/kbuild.txt

+5 −10
Original line number Original line Diff line number Diff line
@@ -232,17 +232,12 @@ KBUILD_LDS 
--------------------------------------------------

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

The linker script with full path. Assigned by the top-level Makefile.

The linker script with full path. Assigned by the top-level Makefile.





KBUILD_VMLINUX_INIT

KBUILD_VMLINUX_OBJS

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

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

All object files for the init (first) part of vmlinux.

All object files for vmlinux. They are linked to vmlinux in the same

Files specified with KBUILD_VMLINUX_INIT are linked first.

order as listed in KBUILD_VMLINUX_OBJS.



KBUILD_VMLINUX_MAIN

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

All object files for the main part of vmlinux.





KBUILD_VMLINUX_LIBS

KBUILD_VMLINUX_LIBS

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

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

All .a "lib" files for vmlinux.

All .a "lib" files for vmlinux. KBUILD_VMLINUX_OBJS and KBUILD_VMLINUX_LIBS

KBUILD_VMLINUX_INIT, KBUILD_VMLINUX_MAIN, and KBUILD_VMLINUX_LIBS together

together specify all the object files used to link vmlinux.
 
specify all the object files used to link vmlinux.

Documentation/kbuild/makefiles.txt

+2 −24
Original line number Original line Diff line number Diff line
@@ -154,13 +154,8 @@ more details, with real examples. 




	Kbuild compiles all the $(obj-y) files.  It then calls

	Kbuild compiles all the $(obj-y) files.  It then calls

	"$(AR) rcSTP" to merge these files into one built-in.a file.

	"$(AR) rcSTP" to merge these files into one built-in.a file.

	This is a thin archive without a symbol table, which makes it

	This is a thin archive without a symbol table. It will be later

	unsuitable as a linker input.

	linked into vmlinux by scripts/link-vmlinux.sh



	The scripts/link-vmlinux.sh script later makes an aggregate

	built-in.a with "${AR} rcsTP", which creates the thin archive

	with a symbol table and an index, making it a valid input for

	the final vmlinux link passes.





	The order of files in $(obj-y) is significant.  Duplicates in

	The order of files in $(obj-y) is significant.  Duplicates in

	the lists are allowed: the first instance will be linked into

	the lists are allowed: the first instance will be linked into
@@ -504,23 +499,6 @@ more details, with real examples. 
	In the above example, -Wno-unused-but-set-variable will be added to

	In the above example, -Wno-unused-but-set-variable will be added to

	KBUILD_CFLAGS only if gcc really accepts it.

	KBUILD_CFLAGS only if gcc really accepts it.





    cc-version

	cc-version returns a numerical version of the $(CC) compiler version.

	The format is <major><minor> where both are two digits. So for example

	gcc 3.41 would return 0341.

	cc-version is useful when a specific $(CC) version is faulty in one

	area, for example -mregparm=3 was broken in some gcc versions

	even though the option was accepted by gcc.



	Example:

		#arch/x86/Makefile

		cflags-y += $(shell \

		if [ $(cc-version) -ge 0300 ] ; then \

			echo "-mregparm=3"; fi ;)



	In the above example, -mregparm=3 is only used for gcc version greater

	than or equal to gcc 3.0.



    cc-ifversion

    cc-ifversion

	cc-ifversion tests the version of $(CC) and equals the fourth parameter

	cc-ifversion tests the version of $(CC) and equals the fourth parameter

	if version expression is true, or the fifth (if given) if the version

	if version expression is true, or the fifth (if given) if the version

Documentation/kbuild/modules.txt

+1 −1
Original line number Original line Diff line number Diff line
@@ -140,7 +140,7 @@ executed to make module versioning work. 
		make -C $KDIR M=$PWD bar.lst

		make -C $KDIR M=$PWD bar.lst

		make -C $KDIR M=$PWD baz.o

		make -C $KDIR M=$PWD baz.o

		make -C $KDIR M=$PWD foo.ko

		make -C $KDIR M=$PWD foo.ko

		make -C $KDIR M=$PWD /

		make -C $KDIR M=$PWD ./









=== 3. Creating a Kbuild File for an External Module

=== 3. Creating a Kbuild File for an External Module

Kbuild

+5 −24
Original line number Original line Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0

# SPDX-License-Identifier: GPL-2.0

#

#

# Kbuild for top-level directory of the kernel

# Kbuild for top-level directory of the kernel

# This file takes care of the following:

# 1) Generate bounds.h

# 2) Generate timeconst.h

# 3) Generate asm-offsets.h (may need bounds.h and timeconst.h)

# 4) Check for missing system calls

# 5) check atomics headers are up-to-date

# 6) Generate constants.py (may need bounds.h)





#####

#####

# 1) Generate bounds.h

# Generate bounds.h





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

bounds-file := include/generated/bounds.h
@@ -21,7 +14,7 @@ $(bounds-file): kernel/bounds.s FORCE 
	$(call filechk,offsets,__LINUX_BOUNDS_H__)

	$(call filechk,offsets,__LINUX_BOUNDS_H__)





#####

#####

# 2) Generate timeconst.h

# Generate timeconst.h





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

timeconst-file := include/generated/timeconst.h
@@ -33,8 +26,7 @@ $(timeconst-file): kernel/time/timeconst.bc FORCE 
	$(call filechk,gentimeconst)

	$(call filechk,gentimeconst)





#####

#####

# 3) Generate asm-offsets.h

# Generate asm-offsets.h

#





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

offsets-file := include/generated/asm-offsets.h
@@ -47,8 +39,7 @@ $(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE 
	$(call filechk,offsets,__ASM_OFFSETS_H__)

	$(call filechk,offsets,__ASM_OFFSETS_H__)





#####

#####

# 4) Check for missing system calls

# Check for missing system calls

#





always += missing-syscalls

always += missing-syscalls

targets += missing-syscalls

targets += missing-syscalls
@@ -60,8 +51,7 @@ missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE 
	$(call cmd,syscalls)

	$(call cmd,syscalls)





#####

#####

# 5) Check atomic headers are up-to-date

# Check atomic headers are up-to-date

#





always += old-atomics

always += old-atomics

targets += old-atomics

targets += old-atomics
@@ -72,14 +62,5 @@ quiet_cmd_atomics = CALL $< 
old-atomics: scripts/atomic/check-atomics.sh FORCE

old-atomics: scripts/atomic/check-atomics.sh FORCE

	$(call cmd,atomics)

	$(call cmd,atomics)





#####

# 6) Generate constants for Python GDB integration

#



extra-$(CONFIG_GDB_SCRIPTS) += build_constants_py



build_constants_py: $(timeconst-file) $(bounds-file)

	@$(MAKE) $(build)=scripts/gdb/linux $@



# Keep these three files during make clean

# Keep these three files during make clean

no-clean-files := $(bounds-file) $(offsets-file) $(timeconst-file)
 
no-clean-files := $(bounds-file) $(offsets-file) $(timeconst-file)