[PATCH 1/2] kbuild: remove redundant $(wildcard ) for rm-files

[PATCH 1/2] kbuild: remove redundant $(wildcard ) for rm-files

[Masahiro Yamada]

The $(wildcard ) is called in quiet_cmd_rmfiles.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index a1c19979e13e..62557fabfee5 100644
--- a/Makefile
+++ b/Makefile
@@ -1512,7 +1512,7 @@ clean: archclean vmlinuxclean resolve_btfids_clean
 
 # mrproper - Delete all generated files, including .config
 #
-mrproper: rm-files := $(wildcard $(MRPROPER_FILES))
+mrproper: rm-files := $(MRPROPER_FILES)
 mrproper-dirs      := $(addprefix _mrproper_,scripts)
 
 PHONY += $(mrproper-dirs) mrproper
-- 
2.40.1

[PATCH 2/2] kbuild: add 'private' to target-specific variables

[Masahiro Yamada]

Currently, Kbuild produces inconsistent results in some cases.

You can do an interesting experiment using the --shuffle option, which
is supported by GNU Make 4.4 or later.

Set CONFIG_KVM_INTEL=y and CONFIG_KVM_AMD=m (or vice versa), and repeat
incremental builds w/wo --shuffle=reverse.

  $ make
    [ snip ]
    CC      arch/x86/kvm/kvm-asm-offsets.s

  $ make --shuffle=reverse
    [ snip ]
    CC [M]  arch/x86/kvm/kvm-asm-offsets.s

  $ make
    [ snip ]
    CC      arch/x86/kvm/kvm-asm-offsets.s

arch/x86/kvm/kvm-asm-offsets.s is rebuilt every time w/wo the [M] marker.

arch/x86/kvm/kvm-asm-offsets.s is built as built-in when it is built as
a prerequisite of arch/x86/kvm/kvm-intel.o, which is built-in.

arch/x86/kvm/kvm-asm-offsets.s is built as modular when it is built as
a prerequisite of arch/x86/kvm/kvm-amd.o, which is a module.

Another odd example is single target builds.

When CONFIG_LKDTM=m, drivers/misc/lkdtm/rodata.o can be built as
built-in or modular, depending on how it is built.

  $ make drivers/misc/lkdtm/lkdtm.o
    [ snip ]
    CC [M]  drivers/misc/lkdtm/rodata.o

  $ make drivers/misc/lkdtm/rodata.o
    [ snip ]
    CC      drivers/misc/lkdtm/rodata.o

drivers/misc/lkdtm/rodata.o is built as modular when it is built as a
prerequisite of another, but built as built-in when it is a final
target.

The same thing happens to drivers/memory/emif-asm-offsets.s when
CONFIG_TI_EMIF_SRAM=m.

  $ make drivers/memory/ti-emif-sram.o
    [ snip ]
    CC [M]  drivers/memory/emif-asm-offsets.s

  $ make drivers/memory/emif-asm-offsets.s
    [ snip ]
    CC      drivers/memory/emif-asm-offsets.s

This is because the part-of-module=y flag defined for the modules is
inherited by its prerequisites.

Target-specific variables are likely intended only for local use.
This commit adds 'private' to them.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 Makefile               | 8 ++++----
 scripts/Makefile.build | 6 +++---
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/Makefile b/Makefile
index 62557fabfee5..25dcc7ead330 100644
--- a/Makefile
+++ b/Makefile
@@ -1255,8 +1255,8 @@ define filechk_version.h
 	echo \#define LINUX_VERSION_SUBLEVEL $(SUBLEVEL)
 endef
 
-$(version_h): PATCHLEVEL := $(or $(PATCHLEVEL), 0)
-$(version_h): SUBLEVEL := $(or $(SUBLEVEL), 0)
+$(version_h): private PATCHLEVEL := $(or $(PATCHLEVEL), 0)
+$(version_h): private SUBLEVEL := $(or $(SUBLEVEL), 0)
 $(version_h): FORCE
 	$(call filechk,version.h)
 
@@ -1500,7 +1500,7 @@ MRPROPER_FILES += include/config include/generated          \
 
 # clean - Delete most, but leave enough to build external modules
 #
-clean: rm-files := $(CLEAN_FILES)
+clean: private rm-files := $(CLEAN_FILES)
 
 PHONY += archclean vmlinuxclean
 
@@ -1512,7 +1512,7 @@ clean: archclean vmlinuxclean resolve_btfids_clean
 
 # mrproper - Delete all generated files, including .config
 #
-mrproper: rm-files := $(MRPROPER_FILES)
+mrproper: private rm-files := $(MRPROPER_FILES)
 mrproper-dirs      := $(addprefix _mrproper_,scripts)
 
 PHONY += $(mrproper-dirs) mrproper
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 43b71c3d0ff6..c9c07a6144eb 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -216,7 +216,7 @@ endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
 
 is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(target-stem).o)$(OBJECT_FILES_NON_STANDARD)n),y)
 
-$(obj)/%.o: objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y))
+$(obj)/%.o: private objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y))
 
 ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
 cmd_warn_shared_object = $(if $(word 2, $(modname-multi)),$(warning $(kbuild-file): $*.o is added to multiple modules: $(modname-multi)))
@@ -437,8 +437,8 @@ define rule_ld_multi_m
 	$(call cmd,gen_objtooldep)
 endef
 
-$(multi-obj-m): objtool-enabled := $(delay-objtool)
-$(multi-obj-m): part-of-module := y
+$(multi-obj-m): private objtool-enabled := $(delay-objtool)
+$(multi-obj-m): private part-of-module := y
 $(multi-obj-m): %.o: %.mod FORCE
 	$(call if_changed_rule,ld_multi_m)
 $(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
-- 
2.40.1

Re: [PATCH 2/2] kbuild: add 'private' to target-specific variables

[Nicolas Schier]

On Sun, Apr 28, 2024 at 12:32:53AM +0900, Masahiro Yamada wrote:
> Currently, Kbuild produces inconsistent results in some cases.
> 
> You can do an interesting experiment using the --shuffle option, which
> is supported by GNU Make 4.4 or later.
> 
> Set CONFIG_KVM_INTEL=y and CONFIG_KVM_AMD=m (or vice versa), and repeat
> incremental builds w/wo --shuffle=reverse.
> 
>   $ make
>     [ snip ]
>     CC      arch/x86/kvm/kvm-asm-offsets.s
> 
>   $ make --shuffle=reverse
>     [ snip ]
>     CC [M]  arch/x86/kvm/kvm-asm-offsets.s
> 
>   $ make
>     [ snip ]
>     CC      arch/x86/kvm/kvm-asm-offsets.s
> 
> arch/x86/kvm/kvm-asm-offsets.s is rebuilt every time w/wo the [M] marker.
> 
> arch/x86/kvm/kvm-asm-offsets.s is built as built-in when it is built as
> a prerequisite of arch/x86/kvm/kvm-intel.o, which is built-in.
> 
> arch/x86/kvm/kvm-asm-offsets.s is built as modular when it is built as
> a prerequisite of arch/x86/kvm/kvm-amd.o, which is a module.
> 
> Another odd example is single target builds.
> 
> When CONFIG_LKDTM=m, drivers/misc/lkdtm/rodata.o can be built as
> built-in or modular, depending on how it is built.
> 
>   $ make drivers/misc/lkdtm/lkdtm.o
>     [ snip ]
>     CC [M]  drivers/misc/lkdtm/rodata.o
> 
>   $ make drivers/misc/lkdtm/rodata.o
>     [ snip ]
>     CC      drivers/misc/lkdtm/rodata.o
> 
> drivers/misc/lkdtm/rodata.o is built as modular when it is built as a
> prerequisite of another, but built as built-in when it is a final
> target.
> 
> The same thing happens to drivers/memory/emif-asm-offsets.s when
> CONFIG_TI_EMIF_SRAM=m.
> 
>   $ make drivers/memory/ti-emif-sram.o
>     [ snip ]
>     CC [M]  drivers/memory/emif-asm-offsets.s
> 
>   $ make drivers/memory/emif-asm-offsets.s
>     [ snip ]
>     CC      drivers/memory/emif-asm-offsets.s
> 
> This is because the part-of-module=y flag defined for the modules is
> inherited by its prerequisites.
> 
> Target-specific variables are likely intended only for local use.
> This commit adds 'private' to them.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---

uh, thanks for fixing this!  (And for the bug documentation, as always!)

I have just one question below.

> 
>  Makefile               | 8 ++++----
>  scripts/Makefile.build | 6 +++---
>  2 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 62557fabfee5..25dcc7ead330 100644
> --- a/Makefile
> +++ b/Makefile
[...]
> @@ -1500,7 +1500,7 @@ MRPROPER_FILES += include/config include/generated          \
>  
>  # clean - Delete most, but leave enough to build external modules
>  #
> -clean: rm-files := $(CLEAN_FILES)
> +clean: private rm-files := $(CLEAN_FILES)

Did you leave 'clean: rm-files := $(KBUILD_EXTMOD)/...' for oot kmods
the way it is (w/o 'private') by intention?

Even though I cannot think of a possible problem without the 'private',
I think it makes sense to change the line as well.

W/ or w/o the 'clean'-update for oot kmods:

Reviewed-by: Nicolas Schier <n.schier@avm.de>

Kind regards,
Nicolas

Re: [PATCH 2/2] kbuild: add 'private' to target-specific variables

[Masahiro Yamada]

On Tue, May 7, 2024 at 8:16 PM Nicolas Schier <nicolas@fjasle.eu> wrote:
>
> On Sun, Apr 28, 2024 at 12:32:53AM +0900, Masahiro Yamada wrote:
> > Currently, Kbuild produces inconsistent results in some cases.
> >
> > You can do an interesting experiment using the --shuffle option, which
> > is supported by GNU Make 4.4 or later.
> >
> > Set CONFIG_KVM_INTEL=y and CONFIG_KVM_AMD=m (or vice versa), and repeat
> > incremental builds w/wo --shuffle=reverse.
> >
> >   $ make
> >     [ snip ]
> >     CC      arch/x86/kvm/kvm-asm-offsets.s
> >
> >   $ make --shuffle=reverse
> >     [ snip ]
> >     CC [M]  arch/x86/kvm/kvm-asm-offsets.s
> >
> >   $ make
> >     [ snip ]
> >     CC      arch/x86/kvm/kvm-asm-offsets.s
> >
> > arch/x86/kvm/kvm-asm-offsets.s is rebuilt every time w/wo the [M] marker.
> >
> > arch/x86/kvm/kvm-asm-offsets.s is built as built-in when it is built as
> > a prerequisite of arch/x86/kvm/kvm-intel.o, which is built-in.
> >
> > arch/x86/kvm/kvm-asm-offsets.s is built as modular when it is built as
> > a prerequisite of arch/x86/kvm/kvm-amd.o, which is a module.
> >
> > Another odd example is single target builds.
> >
> > When CONFIG_LKDTM=m, drivers/misc/lkdtm/rodata.o can be built as
> > built-in or modular, depending on how it is built.
> >
> >   $ make drivers/misc/lkdtm/lkdtm.o
> >     [ snip ]
> >     CC [M]  drivers/misc/lkdtm/rodata.o
> >
> >   $ make drivers/misc/lkdtm/rodata.o
> >     [ snip ]
> >     CC      drivers/misc/lkdtm/rodata.o
> >
> > drivers/misc/lkdtm/rodata.o is built as modular when it is built as a
> > prerequisite of another, but built as built-in when it is a final
> > target.
> >
> > The same thing happens to drivers/memory/emif-asm-offsets.s when
> > CONFIG_TI_EMIF_SRAM=m.
> >
> >   $ make drivers/memory/ti-emif-sram.o
> >     [ snip ]
> >     CC [M]  drivers/memory/emif-asm-offsets.s
> >
> >   $ make drivers/memory/emif-asm-offsets.s
> >     [ snip ]
> >     CC      drivers/memory/emif-asm-offsets.s
> >
> > This is because the part-of-module=y flag defined for the modules is
> > inherited by its prerequisites.
> >
> > Target-specific variables are likely intended only for local use.
> > This commit adds 'private' to them.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> > ---
>
> uh, thanks for fixing this!  (And for the bug documentation, as always!)
>
> I have just one question below.
>
> >
> >  Makefile               | 8 ++++----
> >  scripts/Makefile.build | 6 +++---
> >  2 files changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/Makefile b/Makefile
> > index 62557fabfee5..25dcc7ead330 100644
> > --- a/Makefile
> > +++ b/Makefile
> [...]
> > @@ -1500,7 +1500,7 @@ MRPROPER_FILES += include/config include/generated          \
> >
> >  # clean - Delete most, but leave enough to build external modules
> >  #
> > -clean: rm-files := $(CLEAN_FILES)
> > +clean: private rm-files := $(CLEAN_FILES)
>
> Did you leave 'clean: rm-files := $(KBUILD_EXTMOD)/...' for oot kmods
> the way it is (w/o 'private') by intention?


No. I missed to update this line.

I will fix it up for consistency. Thanks.





>
> Even though I cannot think of a possible problem without the 'private',
> I think it makes sense to change the line as well.
>
> W/ or w/o the 'clean'-update for oot kmods:
>
> Reviewed-by: Nicolas Schier <n.schier@avm.de>
>
> Kind regards,
> Nicolas



-- 
Best Regards
Masahiro Yamada

Re: [PATCH 1/2] kbuild: remove redundant $(wildcard ) for rm-files

[Nicolas Schier]

On Sun, Apr 28, 2024 at 12:32:52AM +0900, Masahiro Yamada wrote:
> The $(wildcard ) is called in quiet_cmd_rmfiles.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
> 
>  Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Makefile b/Makefile
> index a1c19979e13e..62557fabfee5 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1512,7 +1512,7 @@ clean: archclean vmlinuxclean resolve_btfids_clean
>  
>  # mrproper - Delete all generated files, including .config
>  #
> -mrproper: rm-files := $(wildcard $(MRPROPER_FILES))
> +mrproper: rm-files := $(MRPROPER_FILES)
>  mrproper-dirs      := $(addprefix _mrproper_,scripts)
>  
>  PHONY += $(mrproper-dirs) mrproper
> -- 
> 2.40.1
> 

Reviewed-by: Nicolas Schier <n.schier@avm.de>