mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-09-04 20:19:47 +08:00
09bd7c75e5
One of the most remarkable improvements in this cycle is, Kbuild is
now able to cache the result of shell commands. Some variables are
expensive to compute, for example, $(call cc-option,...) invokes the
compiler. It is not efficient to redo this computation every time,
even when we are not actually building anything. Kbuild creates a
hidden file ".cache.mk" that contains invoked shell commands and
their results. The speed-up should be noticeable.
Summary:
- Fix arch build issues (hexagon, sh)
- Clean up various Makefiles and scripts
- Fix wrong usage of {CFLAGS,LDFLAGS}_MODULE in arch Makefiles
- Cache variables that are expensive to compute
- Improve cc-ldopton and ld-option for Clang
- Optimize output directory creation
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1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=zIdO
-----END PGP SIGNATURE-----
Merge tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
"One of the most remarkable improvements in this cycle is, Kbuild is
now able to cache the result of shell commands. Some variables are
expensive to compute, for example, $(call cc-option,...) invokes the
compiler. It is not efficient to redo this computation every time,
even when we are not actually building anything. Kbuild creates a
hidden file ".cache.mk" that contains invoked shell commands and their
results. The speed-up should be noticeable.
Summary:
- Fix arch build issues (hexagon, sh)
- Clean up various Makefiles and scripts
- Fix wrong usage of {CFLAGS,LDFLAGS}_MODULE in arch Makefiles
- Cache variables that are expensive to compute
- Improve cc-ldopton and ld-option for Clang
- Optimize output directory creation"
* tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits)
kbuild: move coccicheck help from scripts/Makefile.help to top Makefile
sh: decompressor: add shipped files to .gitignore
frv: .gitignore: ignore vmlinux.lds
selinux: remove unnecessary assignment to subdir-
kbuild: specify FORCE in Makefile.headersinst as .PHONY target
kbuild: remove redundant mkdir from ./Kbuild
kbuild: optimize object directory creation for incremental build
kbuild: create object directories simpler and faster
kbuild: filter-out PHONY targets from "targets"
kbuild: remove redundant $(wildcard ...) for cmd_files calculation
kbuild: create directory for make cache only when necessary
sh: select KBUILD_DEFCONFIG depending on ARCH
kbuild: fix linker feature test macros when cross compiling with Clang
kbuild: shrink .cache.mk when it exceeds 1000 lines
kbuild: do not call cc-option before KBUILD_CFLAGS initialization
kbuild: Cache a few more calls to the compiler
kbuild: Add a cache for generated variables
kbuild: add forward declaration of default target to Makefile.asm-generic
kbuild: remove KBUILD_SUBDIR_ASFLAGS and KBUILD_SUBDIR_CCFLAGS
hexagon/kbuild: replace CFLAGS_MODULE with KBUILD_CFLAGS_MODULE
...
85 lines
2.2 KiB
Makefile
85 lines
2.2 KiB
Makefile
# 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) Generate constants.py (may need bounds.h)
|
|
|
|
#####
|
|
# 1) Generate bounds.h
|
|
|
|
bounds-file := include/generated/bounds.h
|
|
|
|
always := $(bounds-file)
|
|
targets := kernel/bounds.s
|
|
|
|
# We use internal kbuild rules to avoid the "is up to date" message from make
|
|
kernel/bounds.s: kernel/bounds.c FORCE
|
|
$(call if_changed_dep,cc_s_c)
|
|
|
|
$(obj)/$(bounds-file): kernel/bounds.s FORCE
|
|
$(call filechk,offsets,__LINUX_BOUNDS_H__)
|
|
|
|
#####
|
|
# 2) Generate timeconst.h
|
|
|
|
timeconst-file := include/generated/timeconst.h
|
|
|
|
targets += $(timeconst-file)
|
|
|
|
quiet_cmd_gentimeconst = GEN $@
|
|
define cmd_gentimeconst
|
|
(echo $(CONFIG_HZ) | bc -q $< ) > $@
|
|
endef
|
|
define filechk_gentimeconst
|
|
(echo $(CONFIG_HZ) | bc -q $< )
|
|
endef
|
|
|
|
$(obj)/$(timeconst-file): kernel/time/timeconst.bc FORCE
|
|
$(call filechk,gentimeconst)
|
|
|
|
#####
|
|
# 3) Generate asm-offsets.h
|
|
#
|
|
|
|
offsets-file := include/generated/asm-offsets.h
|
|
|
|
always += $(offsets-file)
|
|
targets += arch/$(SRCARCH)/kernel/asm-offsets.s
|
|
|
|
# We use internal kbuild rules to avoid the "is up to date" message from make
|
|
arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
|
|
$(obj)/$(timeconst-file) $(obj)/$(bounds-file) FORCE
|
|
$(call if_changed_dep,cc_s_c)
|
|
|
|
$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE
|
|
$(call filechk,offsets,__ASM_OFFSETS_H__)
|
|
|
|
#####
|
|
# 4) Check for missing system calls
|
|
#
|
|
|
|
always += missing-syscalls
|
|
targets += missing-syscalls
|
|
|
|
quiet_cmd_syscalls = CALL $<
|
|
cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags) $(missing_syscalls_flags)
|
|
|
|
missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE
|
|
$(call cmd,syscalls)
|
|
|
|
#####
|
|
# 5) Generate constants for Python GDB integration
|
|
#
|
|
|
|
extra-$(CONFIG_GDB_SCRIPTS) += build_constants_py
|
|
|
|
build_constants_py: $(obj)/$(timeconst-file) $(obj)/$(bounds-file)
|
|
@$(MAKE) $(build)=scripts/gdb/linux $@
|
|
|
|
# Keep these three files during make clean
|
|
no-clean-files := $(bounds-file) $(offsets-file) $(timeconst-file)
|