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 Diff line number Diff line
@@ -15,7 +15,7 @@ DT_TMP_SCHEMA := processed-schema.yaml 
extra-y += $(DT_TMP_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 \

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

Documentation/kbuild/kbuild.txt

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

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.

Files specified with KBUILD_VMLINUX_INIT are linked first.



KBUILD_VMLINUX_MAIN

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

All object files for the main part of vmlinux.

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

order as listed in KBUILD_VMLINUX_OBJS.



KBUILD_VMLINUX_LIBS

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

All .a "lib" files for vmlinux.

KBUILD_VMLINUX_INIT, KBUILD_VMLINUX_MAIN, and KBUILD_VMLINUX_LIBS together

specify all the object files used to link vmlinux.
 
All .a "lib" files for vmlinux. KBUILD_VMLINUX_OBJS and KBUILD_VMLINUX_LIBS

together specify all the object files used to link vmlinux.

Documentation/kbuild/makefiles.txt

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


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

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

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

	unsuitable as a linker input.



	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.

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

	linked into vmlinux by scripts/link-vmlinux.sh



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

	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

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

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

Documentation/kbuild/modules.txt

+1 −1
Original line number 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 baz.o

		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

Kbuild

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

#

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



#####

# 2) Generate timeconst.h

# Generate timeconst.h



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



#####

# 3) Generate asm-offsets.h

#

# Generate 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__)



#####

# 4) Check for missing system calls

#

# Check for missing system calls



always += missing-syscalls

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



#####

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

#

# Check atomic headers are up-to-date



always += old-atomics

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

	$(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

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

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