Build system runs ld more often than needed

[Jean Delvare <khali@linux-fr.org>]

Hi Sam,

I have noticed the following problem:

khali@arrakis:~/src/linux-2.6.16-git> make modules
  CHK     include/linux/version.h
  Building modules, stage 2.
  MODPOST
khali@arrakis:~/src/linux-2.6.16-git> touch drivers/media/video/zoran_card.c 
khali@arrakis:~/src/linux-2.6.16-git> make modules
  CHK     include/linux/version.h
  CC [M]  drivers/media/video/zoran_card.o
  LD [M]  drivers/media/video/zr36067.o
  LD [M]  drivers/media/video/msp3400.o
  LD [M]  drivers/media/video/tuner.o
  Building modules, stage 2.
  MODPOST
  LD [M]  drivers/media/video/msp3400.ko
  LD [M]  drivers/media/video/tuner.ko
  LD [M]  drivers/media/video/zr36067.ko
khali@arrakis:~/src/linux-2.6.16-git>

See how unrelated modules are linked again?

I investigated further and it seems to happen whenever a given Makefile
has more than one composite object definition. In the case of
drivers/media/video, the following composite objects are defined:

zoran-objs      :=	zr36120.o zr36120_i2c.o zr36120_mem.o
zr36067-objs	:=	zoran_procfs.o zoran_device.o \
			zoran_driver.o zoran_card.o
tuner-objs	:=	tuner-core.o tuner-types.o tuner-simple.o \
			mt20xx.o tda8290.o tea5767.o

msp3400-objs	:=	msp3400-driver.o msp3400-kthreads.o

I have the following enabled:

CONFIG_VIDEO_MSP3400=m
CONFIG_VIDEO_ZORAN=m
CONFIG_VIDEO_TUNER=m

So msp3400 and tuner are relinked whenever I make a change to the
zr36067 driver.

I was able to reproduce the problem in drivers/scsi so it's not local
to the media/video area. I was also able to reproduce the problem back
to Linux 2.6.0 so the problem is not new.

Can this be looked upon?

Thanks,
-- 
Jean Delvare