From a2430b25c31840a6dcbf95c65415d5fee2984dbc Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sat, 19 Nov 2022 04:15:50 +0900 Subject: kbuild: add kbuild-file macro While building, installing, cleaning, Kbuild visits sub-directories and includes 'Kbuild' or 'Makefile' that exists there. Add 'kbuild-file' macro, and reuse it from scripts/Makefie.* Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier Reviewed-by: Alexander Lobakin Tested-by: Alexander Lobakin --- scripts/Kbuild.include | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'scripts/Kbuild.include') diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 2bc08ace38a3..cbe28744637b 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -40,6 +40,11 @@ escsq = $(subst $(squote),'\$(squote)',$1) # Quote a string to pass it to C files. foo => '"foo"' stringify = $(squote)$(quote)$1$(quote)$(squote) +### +# The path to Kbuild or Makefile. Kbuild has precedence over Makefile. +kbuild-dir = $(if $(filter /%,$(src)),$(src),$(srctree)/$(src)) +kbuild-file = $(or $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Makefile) + ### # Easy method for doing a status message kecho := : -- cgit v1.2.3 From fccb3d3eda8d19b893e1fd18e8c70b78784b2a72 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sun, 11 Dec 2022 11:46:47 +0900 Subject: kbuild: add test-{ge,gt,le,lt} macros GNU Make 4.4 introduced $(intcmp ...), which is useful to compare two integers without forking a new process. Add test-{ge,gt,le,lt} macros, which work more efficiently with GNU Make >= 4.4. For older Make versions, they fall back to the 'test' shell command. The first two parameters to $(intcmp ...) must not be empty. To avoid the syntax error, I appended '0' to them. Fortunately, '00' is treated as '0'. This is needed because CONFIG options may expand to an empty string when the kernel configuration is not included. Signed-off-by: Masahiro Yamada Acked-by: Palmer Dabbelt # RISC-V Reviewed-by: Nathan Chancellor Reviewed-by: Nicolas Schier --- Makefile | 2 +- arch/riscv/Makefile | 2 +- arch/x86/Makefile | 2 +- scripts/Kbuild.include | 16 ++++++++++++++++ scripts/Makefile.compiler | 4 ++-- 5 files changed, 21 insertions(+), 5 deletions(-) (limited to 'scripts/Kbuild.include') diff --git a/Makefile b/Makefile index 6b047daa46cc..ff36288ae671 100644 --- a/Makefile +++ b/Makefile @@ -994,7 +994,7 @@ KBUILD_LDFLAGS += -mllvm -import-instr-limit=5 # Check for frame size exceeding threshold during prolog/epilog insertion # when using lld < 13.0.0. ifneq ($(CONFIG_FRAME_WARN),0) -ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0) +ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y) KBUILD_LDFLAGS += -plugin-opt=-warn-stack-size=$(CONFIG_FRAME_WARN) endif endif diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index 0d13b597cb55..faf2c2177094 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -37,7 +37,7 @@ else endif ifeq ($(CONFIG_LD_IS_LLD),y) -ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 150000; echo $$?),0) +ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 150000),y) KBUILD_CFLAGS += -mno-relax KBUILD_AFLAGS += -mno-relax ifndef CONFIG_AS_IS_LLVM diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 415a5d138de4..e72c7a49cd59 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -211,7 +211,7 @@ endif KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE) ifdef CONFIG_LTO_CLANG -ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0) +ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y) KBUILD_LDFLAGS += -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8) endif endif diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index cbe28744637b..3be7c2d75667 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -11,6 +11,22 @@ space := $(empty) $(empty) space_escape := _-_SPACE_-_ pound := \# +### +# Comparison macros. +# Usage: $(call test-lt, $(CONFIG_LLD_VERSION), 150000) +# +# Use $(intcmp ...) if supported. (Make >= 4.4) +# Otherwise, fall back to the 'test' shell command. +ifeq ($(intcmp 1,0,,,y),y) +test-ge = $(intcmp $(strip $1)0, $(strip $2)0,,y,y) +test-gt = $(intcmp $(strip $1)0, $(strip $2)0,,,y) +else +test-ge = $(shell test $(strip $1)0 -ge $(strip $2)0 && echo y) +test-gt = $(shell test $(strip $1)0 -gt $(strip $2)0 && echo y) +endif +test-le = $(call test-ge, $2, $1) +test-lt = $(call test-gt, $2, $1) + ### # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o dot-target = $(dir $@).$(notdir $@) diff --git a/scripts/Makefile.compiler b/scripts/Makefile.compiler index 20d353dcabfb..3d8adfd34af1 100644 --- a/scripts/Makefile.compiler +++ b/scripts/Makefile.compiler @@ -63,11 +63,11 @@ cc-disable-warning = $(call try-run,\ # gcc-min-version # Usage: cflags-$(call gcc-min-version, 70100) += -foo -gcc-min-version = $(shell [ $(CONFIG_GCC_VERSION)0 -ge $(1)0 ] && echo y) +gcc-min-version = $(call test-ge, $(CONFIG_GCC_VERSION), $1) # clang-min-version # Usage: cflags-$(call clang-min-version, 110000) += -foo -clang-min-version = $(shell [ $(CONFIG_CLANG_VERSION)0 -ge $(1)0 ] && echo y) +clang-min-version = $(call test-ge, $(CONFIG_CLANG_VERSION), $1) # ld-option # Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y) -- cgit v1.2.3 From 6768fa4bcb6c1618248f135d04b9287ba2724ae0 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sun, 11 Dec 2022 11:54:47 +0900 Subject: kbuild: add read-file macro Since GNU Make 4.2, $(file ...) supports the read operater '<', which is useful to read a file without forking a new process. No warning is shown even if the input file is missing. For older Make versions, it falls back to the cat command. Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier Reviewed-by: Alexander Lobakin Tested-by: Alexander Lobakin --- Makefile | 2 +- scripts/Kbuild.include | 14 ++++++++++++++ scripts/Makefile.modfinal | 2 +- scripts/Makefile.modinst | 2 +- 4 files changed, 17 insertions(+), 3 deletions(-) (limited to 'scripts/Kbuild.include') diff --git a/Makefile b/Makefile index ff36288ae671..591485152a95 100644 --- a/Makefile +++ b/Makefile @@ -376,7 +376,7 @@ else # !mixed-build include $(srctree)/scripts/Kbuild.include # Read KERNELRELEASE from include/config/kernel.release (if it exists) -KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null) +KERNELRELEASE = $(call read-file, include/config/kernel.release) KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION) export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 3be7c2d75667..21e76ba0de17 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -10,6 +10,10 @@ empty := space := $(empty) $(empty) space_escape := _-_SPACE_-_ pound := \# +define newline + + +endef ### # Comparison macros. @@ -61,6 +65,16 @@ stringify = $(squote)$(quote)$1$(quote)$(squote) kbuild-dir = $(if $(filter /%,$(src)),$(src),$(srctree)/$(src)) kbuild-file = $(or $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Makefile) +### +# Read a file, replacing newlines with spaces +# +# Make 4.2 or later can read a file by using its builtin function. +ifneq ($(filter-out 3.% 4.0 4.1, $(MAKE_VERSION)),) +read-file = $(subst $(newline),$(space),$(file < $1)) +else +read-file = $(shell cat $1 2>/dev/null) +endif + ### # Easy method for doing a status message kecho := : diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal index 4705d32388f3..83f2797e530c 100644 --- a/scripts/Makefile.modfinal +++ b/scripts/Makefile.modfinal @@ -13,7 +13,7 @@ include $(srctree)/scripts/Kbuild.include include $(srctree)/scripts/Makefile.lib # find all modules listed in modules.order -modules := $(shell cat $(MODORDER)) +modules := $(call read-file, $(MODORDER)) __modfinal: $(modules) @: diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst index f4cff42069ad..65aac6be78ec 100644 --- a/scripts/Makefile.modinst +++ b/scripts/Makefile.modinst @@ -9,7 +9,7 @@ __modinst: include include/config/auto.conf include $(srctree)/scripts/Kbuild.include -modules := $(shell cat $(MODORDER)) +modules := $(call read-file, $(MODORDER)) ifeq ($(KBUILD_EXTMOD),) dst := $(MODLIB)/kernel -- cgit v1.2.3 From 875ef1a57f32fcb91010dc9bc8bd1166956a579e Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sun, 11 Dec 2022 12:10:59 +0900 Subject: kbuild: use .NOTINTERMEDIATE for future GNU Make versions In Kbuild, some files are generated by chains of pattern/implicit rules. For example, *.dtb.o files in drivers/of/unittest-data/Makefile are generated by the chain of 3 pattern rules, like this: %.dts -> %.dtb -> %.dtb.S -> %.dtb.o Here, %.dts is the real source, %.dtb.o is the final target. %.dtb and %.dtb.S are called "intermediate files". As GNU Make manual [1] says, intermediate files are treated differently in two ways: (a) The first difference is what happens if the intermediate file does not exist. If an ordinary file 'b' does not exist, and make considers a target that depends on 'b', it invariably creates 'b' and then updates the target from 'b'. But if 'b' is an intermediate file, then make can leave well enough alone: it won't create 'b' unless one of its prerequisites is out of date. This means the target depending on 'b' won't be rebuilt either, unless there is some other reason to update that target: for example the target doesn't exist or a different prerequisite is newer than the target. (b) The second difference is that if make does create 'b' in order to update something else, it deletes 'b' later on after it is no longer needed. Therefore, an intermediate file which did not exist before make also does not exist after make. make reports the deletion to you by printing a 'rm' command showing which file it is deleting. The combination of these is problematic for Kbuild because most of the build rules depend on FORCE and the if_changed* macros really determine if the target should be updated. So, all missing files, whether they are intermediate or not, are always rebuilt. To see the problem, delete ".SECONDARY:" from scripts/Kbuild.include, and repeat this command: $ make allmodconfig drivers/of/unittest-data/ The intermediate files will be deleted, which results in rebuilding intermediate and final objects in the next run of make. In the old days, people suppressed (b) in inconsistent ways. As commit 54a702f70589 ("kbuild: mark $(targets) as .SECONDARY and remove .PRECIOUS markers") noted, you should not use .PRECIOUS because .PRECIOUS has the following behavior (c), which is not likely what you want. (c) If make is killed or interrupted during the execution of their recipes, the target is not deleted. Also, the target is not deleted on error even if .DELETE_ON_ERROR is specified. .SECONDARY is a much better way to disable (b), but a small problem is that .SECONDARY enables (a), which gives a side-effect to $?; prerequisites marked as .SECONDARY do not appear in $?. This is a drawback for Kbuild. I thought it was a bug and opened a bug report. As Paul, the GNU Make maintainer, concluded in [2], this is not a bug. A good news is that, GNU Make 4.4 added the perfect solution, .NOTINTERMEDIATE, which cancels both (a) and (b). For clarificaton, my understanding of .INTERMEDIATE, .SECONDARY, .PRECIOUS and .NOTINTERMEDIATE are as follows: (a) (b) (c) .INTERMEDIATE enable enable disable .SECONDARY enable disable disable .PRECIOUS disable disable enable .NOTINTERMEDIATE disable disable disable However, GNU Make 4.4 has a bug for the global .NOTINTERMEDIATE. [3] It was fixed by commit 6164608900ad ("[SV 63417] Ensure global .NOTINTERMEDIATE disables all intermediates"), and will be available in the next release of GNU Make. The following is the gain for .NOTINTERMEDIATE: [Current Make] $ make allnoconfig vmlinux [ full build ] $ rm include/linux/device.h $ make vmlinux CALL scripts/checksyscalls.sh Make does not notice the removal of . [Future Make] $ make-latest allnoconfig vmlinux [ full build ] $ rm include/linux/device.h $ make-latest vmlinux CC arch/x86/kernel/asm-offsets.s In file included from ./include/linux/writeback.h:13, from ./include/linux/memcontrol.h:22, from ./include/linux/swap.h:9, from ./include/linux/suspend.h:5, from arch/x86/kernel/asm-offsets.c:13: ./include/linux/blk_types.h:11:10: fatal error: linux/device.h: No such file or directory 11 | #include | ^~~~~~~~~~~~~~~~ compilation terminated. make-latest[1]: *** [scripts/Makefile.build:114: arch/x86/kernel/asm-offsets.s] Error 1 make-latest: *** [Makefile:1282: prepare0] Error 2 Make notices the removal of , and rebuilds objects that depended on . There exists a source file that includes , and it raises an error. To see detailed background information, refer to commit 2d3b1b8f0da7 ("kbuild: drop $(wildcard $^) check in if_changed* for faster rebuild"). [1]: https://www.gnu.org/software/make/manual/make.html#Chained-Rules [2]: https://savannah.gnu.org/bugs/?55532 [3]: https://savannah.gnu.org/bugs/?63417 Signed-off-by: Masahiro Yamada --- scripts/Kbuild.include | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'scripts/Kbuild.include') diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 21e76ba0de17..2f7356b2990b 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -185,9 +185,6 @@ endif make-cmd = $(call escsq,$(subst $(pound),$$(pound),$(subst $$,$$$$,$(cmd_$(1))))) # Find any prerequisites that are newer than target or that do not exist. -# (This is not true for now; $? should contain any non-existent prerequisites, -# but it does not work as expected when .SECONDARY is present. This seems a bug -# of GNU Make.) # PHONY targets skipped in both cases. newer-prereqs = $(filter-out $(PHONY),$?) @@ -263,4 +260,14 @@ endif .DELETE_ON_ERROR: # do not delete intermediate files automatically +# +# .NOTINTERMEDIATE is more correct, but only available on newer Make versions. +# Make 4.4 introduced .NOTINTERMEDIATE, and it appears in .FEATURES, but the +# global .NOTINTERMEDIATE does not work. We can use it on Make > 4.4. +# Use .SECONDARY for older Make versions, but "newer-prereq" cannot detect +# deleted files. +ifneq ($(and $(filter notintermediate, $(.FEATURES)),$(filter-out 4.4,$(MAKE_VERSION))),) +.NOTINTERMEDIATE: +else .SECONDARY: +endif -- cgit v1.2.3