Why build empty object files in drivers/media?

Why build empty object files in drivers/media?

[Chuck Ebbert]

I have this in my .config file for 2.6.13-rc3:


#
# Multimedia devices
#
# CONFIG_VIDEO_DEV is not set

#
# Digital Video Broadcasting Devices
#
# CONFIG_DVB is not set


And yet these completely empty files are being built:


$ find drivers/media -name built-in.o | xargs ls -go
-rw-rw-r--  1 305 Jul 16 00:20 drivers/media/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/common/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/dvb/b2c2/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/dvb/bt8xx/built-in.o
-rw-rw-r--  1 305 Jul 16 00:20 drivers/media/dvb/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/dvb/cinergyT2/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/dvb/dvb-core/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/dvb/dvb-usb/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/dvb/frontends/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/dvb/pluto2/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/dvb/ttpci/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/dvb/ttusb-budget/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/dvb/ttusb-dec/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/radio/built-in.o
-rw-rw-r--  1   8 Jul 16 00:20 drivers/media/video/built-in.o

$ size drivers/media/built-in.o
   text    data     bss     dec     hex filename
      0       0       0       0       0 drivers/media/built-in.o


__
Chuck

Re: Why build empty object files in drivers/media?

[Sam Ravnborg]

On Thu, Jul 21, 2005 at 11:06:21PM -0400, Chuck Ebbert wrote:
> 
> I have this in my .config file for 2.6.13-rc3:
> 
> 
> #
> # Multimedia devices
> #
> # CONFIG_VIDEO_DEV is not set
> 
> #
> # Digital Video Broadcasting Devices
> #
> # CONFIG_DVB is not set
> 
> 
> And yet these completely empty files are being built:
> 
> ...
kbuild is told to visit these directories - and then it build an empty
.o file to make linking step possible.
The only solution is to tell kbuild not to visit these directories
unless they are in real use.
Following untested patch should do the trick. But the media people must
check if before being applied since I have only taken a brief look at
the Kconfig and Makefile files.

	Sam

diff --git a/drivers/media/Makefile b/drivers/media/Makefile
--- a/drivers/media/Makefile
+++ b/drivers/media/Makefile
@@ -2,4 +2,7 @@
 # Makefile for the kernel multimedia device drivers.
 #
 
-obj-y        := video/ radio/ dvb/ common/
+obj-y                   := common/
+obj-$(CONFIG_VIDEO_DEV) := video/
+obj-$(CONFIG_VIDEO_DEV) := radio/
+obj-$(CONFIG_DVB)       := dvb/

Re: Why build empty object files in drivers/media?

[Olaf Dietsche]

Sam Ravnborg <sam@ravnborg.org> writes:

> +obj-$(CONFIG_VIDEO_DEV) := video/
> +obj-$(CONFIG_VIDEO_DEV) := radio/

  s/VIDEO/RADIO/

Regards, Olaf.

Re: Why build empty object files in drivers/media?

[Sam Ravnborg]

On Fri, Jul 22, 2005 at 11:18:13PM +0200, Olaf Dietsche wrote:
> Sam Ravnborg <sam@ravnborg.org> writes:
> 
> > +obj-$(CONFIG_VIDEO_DEV) := video/
> > +obj-$(CONFIG_VIDEO_DEV) := radio/
> 
>   s/VIDEO/RADIO/

If you look at drivers/media/radio/Kconfig you will see that the above
is coorect. Thre is no CONFIG_RADIO_DEV.

	Sam

Re: Why build empty object files in drivers/media?

[Keith Owens]

On Fri, 22 Jul 2005 19:46:00 +0000, 
Sam Ravnborg <sam@ravnborg.org> wrote:
>On Thu, Jul 21, 2005 at 11:06:21PM -0400, Chuck Ebbert wrote:
>> 
>> I have this in my .config file for 2.6.13-rc3:
>> 
>> 
>> #
>> # Multimedia devices
>> #
>> # CONFIG_VIDEO_DEV is not set
>> 
>> #
>> # Digital Video Broadcasting Devices
>> #
>> # CONFIG_DVB is not set
>> 
>> 
>> And yet these completely empty files are being built:
>> 
>> ...
>kbuild is told to visit these directories - and then it build an empty
>.o file to make linking step possible.
>The only solution is to tell kbuild not to visit these directories
>unless they are in real use.
>Following untested patch should do the trick. But the media people must
>check if before being applied since I have only taken a brief look at
>the Kconfig and Makefile files.
>
>	Sam
>
>diff --git a/drivers/media/Makefile b/drivers/media/Makefile
>--- a/drivers/media/Makefile
>+++ b/drivers/media/Makefile
>@@ -2,4 +2,7 @@
> # Makefile for the kernel multimedia device drivers.
> #
> 
>-obj-y        := video/ radio/ dvb/ common/
>+obj-y                   := common/
>+obj-$(CONFIG_VIDEO_DEV) := video/
>+obj-$(CONFIG_VIDEO_DEV) := radio/
>+obj-$(CONFIG_DVB)       := dvb/

That should be +=, not :=

+obj-$(CONFIG_VIDEO_DEV) += video/
+obj-$(CONFIG_VIDEO_DEV) += radio/
+obj-$(CONFIG_DVB)       += dvb/

Re: Why build empty object files in drivers/media?

[Johannes Stezenbach]

On Sun, Jul 24, 2005 at 08:58:45AM +0000, Sam Ravnborg wrote:
> On Sun, Jul 24, 2005 at 04:10:13PM +1000, Keith Owens wrote:
> > >
> > >diff --git a/drivers/media/Makefile b/drivers/media/Makefile
> > >--- a/drivers/media/Makefile
> > >+++ b/drivers/media/Makefile
> > >@@ -2,4 +2,7 @@
> > > # Makefile for the kernel multimedia device drivers.
> > > #
> > > 
> > >-obj-y        := video/ radio/ dvb/ common/
> > >+obj-y                   := common/
> > >+obj-$(CONFIG_VIDEO_DEV) := video/
> > >+obj-$(CONFIG_VIDEO_DEV) := radio/
> > >+obj-$(CONFIG_DVB)       := dvb/
> > 
> > That should be +=, not :=
> > 
> > +obj-$(CONFIG_VIDEO_DEV) += video/
> > +obj-$(CONFIG_VIDEO_DEV) += radio/
> > +obj-$(CONFIG_DVB)       += dvb/
> 
> Correct - thanks!

OK, I'll pick this up and put it in CVS.

Thanks,
Johannes