[2/5] kbuild: define KBUILD_MODNAME even if multiple modules share objects

Message ID 1520471103-10089-3-git-send-email-yamada.masahiro@socionext.com
State New
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Series
  • kbuild: always define KBUILD_MODNAME, and clean-up/fix modname
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Commit Message

Masahiro Yamada March 8, 2018, 1:05 a.m.
Currently, KBUILD_MODNAME is defined only when $(modname) contains
just one word.  If an object is shared among multiple modules,
undefined KBUILD_MODNAME could cause a build error.  For example,
if CONFIG_DYNAMIC_DEBUG is enabled, any call of printk() populates
.modname, then fails to build due to undefined KBUILD_MODNAME.

Take the following code as an example:

  obj-m += foo.o
  obj-m += bar.o
  foo-objs := foo-bar-common.o foo-main.o
  bar-objs := foo-bar-common.o bar-main.o

In this case, there is room for argument what to define for
KBUILD_MODNAME when foo-bar-common.o is being compiled.
"foo", "bar", or what else?

One idea is to define colon-separated modules that share the object,
in this case, "bar:foo" (modules are sorted alphabetically by
$(sort ...).

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

---

 scripts/Makefile.lib | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

-- 
2.7.4

Comments

Cao jin March 8, 2018, 10:11 a.m. | #1
On 03/08/2018 09:05 AM, Masahiro Yamada wrote:
> Currently, KBUILD_MODNAME is defined only when $(modname) contains

> just one word.  If an object is shared among multiple modules,

> undefined KBUILD_MODNAME could cause a build error.  For example,

> if CONFIG_DYNAMIC_DEBUG is enabled, any call of printk() populates

> .modname, then fails to build due to undefined KBUILD_MODNAME.

> 

> Take the following code as an example:

> 

>   obj-m += foo.o

>   obj-m += bar.o

>   foo-objs := foo-bar-common.o foo-main.o

>   bar-objs := foo-bar-common.o bar-main.o

> 

> In this case, there is room for argument what to define for

> KBUILD_MODNAME when foo-bar-common.o is being compiled.

> "foo", "bar", or what else?

> 

> One idea is to define colon-separated modules that share the object,

> in this case, "bar:foo" (modules are sorted alphabetically by

> $(sort ...).

> 

> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

> ---

> 

>  scripts/Makefile.lib | 9 +++++----

>  1 file changed, 5 insertions(+), 4 deletions(-)

> 

> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib

> index a7e315f..a1fbd6a 100644

> --- a/scripts/Makefile.lib

> +++ b/scripts/Makefile.lib

> @@ -92,8 +92,7 @@ subdir-ym	:= $(addprefix $(obj)/,$(subdir-ym))

>  #       differ in different configs.

>  name-fix = $(squote)$(quote)$(subst $(comma),_,$(subst -,_,$1))$(quote)$(squote)

>  basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget))

> -modname_flags  = $(if $(filter 1,$(words $(modname))),\

> -                 -DKBUILD_MODNAME=$(call name-fix,$(modname)))

> +modname_flags  = -DKBUILD_MODNAME=$(call name-fix,$(modname))

>  


I guess there is comment also need to be modified above this code hunk:

Note: Files that end up in two or more modules are compiled without the
      KBUILD_MODNAME definition. The reason is that any made-up name
      would differ in different configs.
-- 
Sincerely,
Cao jin
Masahiro Yamada March 8, 2018, 10:21 a.m. | #2
2018-03-08 19:11 GMT+09:00 Cao jin <caoj.fnst@cn.fujitsu.com>:
>

>

> On 03/08/2018 09:05 AM, Masahiro Yamada wrote:

>> Currently, KBUILD_MODNAME is defined only when $(modname) contains

>> just one word.  If an object is shared among multiple modules,

>> undefined KBUILD_MODNAME could cause a build error.  For example,

>> if CONFIG_DYNAMIC_DEBUG is enabled, any call of printk() populates

>> .modname, then fails to build due to undefined KBUILD_MODNAME.

>>

>> Take the following code as an example:

>>

>>   obj-m += foo.o

>>   obj-m += bar.o

>>   foo-objs := foo-bar-common.o foo-main.o

>>   bar-objs := foo-bar-common.o bar-main.o

>>

>> In this case, there is room for argument what to define for

>> KBUILD_MODNAME when foo-bar-common.o is being compiled.

>> "foo", "bar", or what else?

>>

>> One idea is to define colon-separated modules that share the object,

>> in this case, "bar:foo" (modules are sorted alphabetically by

>> $(sort ...).

>>

>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

>> ---

>>

>>  scripts/Makefile.lib | 9 +++++----

>>  1 file changed, 5 insertions(+), 4 deletions(-)

>>

>> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib

>> index a7e315f..a1fbd6a 100644

>> --- a/scripts/Makefile.lib

>> +++ b/scripts/Makefile.lib

>> @@ -92,8 +92,7 @@ subdir-ym   := $(addprefix $(obj)/,$(subdir-ym))

>>  #       differ in different configs.

>>  name-fix = $(squote)$(quote)$(subst $(comma),_,$(subst -,_,$1))$(quote)$(squote)

>>  basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget))

>> -modname_flags  = $(if $(filter 1,$(words $(modname))),\

>> -                 -DKBUILD_MODNAME=$(call name-fix,$(modname)))

>> +modname_flags  = -DKBUILD_MODNAME=$(call name-fix,$(modname))

>>

>

> I guess there is comment also need to be modified above this code hunk:

>

> Note: Files that end up in two or more modules are compiled without the

>       KBUILD_MODNAME definition. The reason is that any made-up name

>       would differ in different configs.



Why do I have to add lying comments here?

The commit subject/log claims KBUILD_MODNAME should be _always_ defined.



-- 
Best Regards
Masahiro Yamada
Cao jin March 8, 2018, 10:25 a.m. | #3
Masahiro-san

On 03/08/2018 06:21 PM, Masahiro Yamada wrote:
> 2018-03-08 19:11 GMT+09:00 Cao jin <caoj.fnst@cn.fujitsu.com>:

>>

>>

>> On 03/08/2018 09:05 AM, Masahiro Yamada wrote:

>>> Currently, KBUILD_MODNAME is defined only when $(modname) contains

>>> just one word.  If an object is shared among multiple modules,

>>> undefined KBUILD_MODNAME could cause a build error.  For example,

>>> if CONFIG_DYNAMIC_DEBUG is enabled, any call of printk() populates

>>> .modname, then fails to build due to undefined KBUILD_MODNAME.

>>>

>>> Take the following code as an example:

>>>

>>>   obj-m += foo.o

>>>   obj-m += bar.o

>>>   foo-objs := foo-bar-common.o foo-main.o

>>>   bar-objs := foo-bar-common.o bar-main.o

>>>

>>> In this case, there is room for argument what to define for

>>> KBUILD_MODNAME when foo-bar-common.o is being compiled.

>>> "foo", "bar", or what else?

>>>

>>> One idea is to define colon-separated modules that share the object,

>>> in this case, "bar:foo" (modules are sorted alphabetically by

>>> $(sort ...).

>>>

>>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

>>> ---

>>>

>>>  scripts/Makefile.lib | 9 +++++----

>>>  1 file changed, 5 insertions(+), 4 deletions(-)

>>>

>>> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib

>>> index a7e315f..a1fbd6a 100644

>>> --- a/scripts/Makefile.lib

>>> +++ b/scripts/Makefile.lib

>>> @@ -92,8 +92,7 @@ subdir-ym   := $(addprefix $(obj)/,$(subdir-ym))

>>>  #       differ in different configs.

>>>  name-fix = $(squote)$(quote)$(subst $(comma),_,$(subst -,_,$1))$(quote)$(squote)

>>>  basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget))

>>> -modname_flags  = $(if $(filter 1,$(words $(modname))),\

>>> -                 -DKBUILD_MODNAME=$(call name-fix,$(modname)))

>>> +modname_flags  = -DKBUILD_MODNAME=$(call name-fix,$(modname))

>>>

>>

>> I guess there is comment also need to be modified above this code hunk:

>>

>> Note: Files that end up in two or more modules are compiled without the

>>       KBUILD_MODNAME definition. The reason is that any made-up name

>>       would differ in different configs.

> 

> 

> Why do I have to add lying comments here?

> 

> The commit subject/log claims KBUILD_MODNAME should be _always_ defined.

> 


I feel you misunderstand my intention, the comment I mentioned is
already there, so they should be modified according to your patch.

-- 
Sincerely,
Cao jin
Masahiro Yamada March 8, 2018, 10:29 a.m. | #4
2018-03-08 19:25 GMT+09:00 Cao jin <caoj.fnst@cn.fujitsu.com>:
> Masahiro-san

>

> On 03/08/2018 06:21 PM, Masahiro Yamada wrote:

>> 2018-03-08 19:11 GMT+09:00 Cao jin <caoj.fnst@cn.fujitsu.com>:

>>>

>>>

>>> On 03/08/2018 09:05 AM, Masahiro Yamada wrote:

>>>> Currently, KBUILD_MODNAME is defined only when $(modname) contains

>>>> just one word.  If an object is shared among multiple modules,

>>>> undefined KBUILD_MODNAME could cause a build error.  For example,

>>>> if CONFIG_DYNAMIC_DEBUG is enabled, any call of printk() populates

>>>> .modname, then fails to build due to undefined KBUILD_MODNAME.

>>>>

>>>> Take the following code as an example:

>>>>

>>>>   obj-m += foo.o

>>>>   obj-m += bar.o

>>>>   foo-objs := foo-bar-common.o foo-main.o

>>>>   bar-objs := foo-bar-common.o bar-main.o

>>>>

>>>> In this case, there is room for argument what to define for

>>>> KBUILD_MODNAME when foo-bar-common.o is being compiled.

>>>> "foo", "bar", or what else?

>>>>

>>>> One idea is to define colon-separated modules that share the object,

>>>> in this case, "bar:foo" (modules are sorted alphabetically by

>>>> $(sort ...).

>>>>

>>>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

>>>> ---

>>>>

>>>>  scripts/Makefile.lib | 9 +++++----

>>>>  1 file changed, 5 insertions(+), 4 deletions(-)

>>>>

>>>> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib

>>>> index a7e315f..a1fbd6a 100644

>>>> --- a/scripts/Makefile.lib

>>>> +++ b/scripts/Makefile.lib

>>>> @@ -92,8 +92,7 @@ subdir-ym   := $(addprefix $(obj)/,$(subdir-ym))

>>>>  #       differ in different configs.

>>>>  name-fix = $(squote)$(quote)$(subst $(comma),_,$(subst -,_,$1))$(quote)$(squote)

>>>>  basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget))

>>>> -modname_flags  = $(if $(filter 1,$(words $(modname))),\

>>>> -                 -DKBUILD_MODNAME=$(call name-fix,$(modname)))

>>>> +modname_flags  = -DKBUILD_MODNAME=$(call name-fix,$(modname))

>>>>

>>>

>>> I guess there is comment also need to be modified above this code hunk:

>>>

>>> Note: Files that end up in two or more modules are compiled without the

>>>       KBUILD_MODNAME definition. The reason is that any made-up name

>>>       would differ in different configs.

>>

>>

>> Why do I have to add lying comments here?

>>

>> The commit subject/log claims KBUILD_MODNAME should be _always_ defined.

>>

>

> I feel you misunderstand my intention, the comment I mentioned is

> already there, so they should be modified according to your patch.

>


Ugh.  Sorry I missed your intention.

I will remove the comment.  Thanks!



-- 
Best Regards
Masahiro Yamada

Patch

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index a7e315f..a1fbd6a 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -92,8 +92,7 @@  subdir-ym	:= $(addprefix $(obj)/,$(subdir-ym))
 #       differ in different configs.
 name-fix = $(squote)$(quote)$(subst $(comma),_,$(subst -,_,$1))$(quote)$(squote)
 basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget))
-modname_flags  = $(if $(filter 1,$(words $(modname))),\
-                 -DKBUILD_MODNAME=$(call name-fix,$(modname)))
+modname_flags  = -DKBUILD_MODNAME=$(call name-fix,$(modname))
 
 orig_c_flags   = $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) \
                  $(ccflags-y) $(CFLAGS_$(basetarget).o)
@@ -174,8 +173,10 @@  dtc_cpp_flags  = -Wp,-MD,$(depfile).pre.tmp -nostdinc                    \
 		 -undef -D__DTS__
 
 # Finds the multi-part object the current object will be linked into
-modname-multi = $(sort $(foreach m,$(multi-used),\
-		$(if $(filter $*.o, $($(m:.o=-objs)) $($(m:.o=-y))),$(m:.o=))))
+# If the object belongs to two or more multi-part objects, all of them are
+# concatenated with a colon separator.
+modname-multi = $(subst $(space),:,$(sort $(foreach m,$(multi-used),\
+		$(if $(filter $*.o, $($(m:.o=-objs)) $($(m:.o=-y))),$(m:.o=)))))
 
 # Useful for describing the dependency of composite objects
 # Usage: