Re: [build bug, 2.6.24-rc1] CONFIG_VIDEO_DEV=m & CONFIG_VIDEO_SAA7146_VV=y

[Johannes Stezenbach <js@linuxtv.org>]

On Mon, Oct 29, 2007, Ingo Molnar wrote:
> * Randy Dunlap <randy.dunlap@oracle.com> wrote:
> 
> > > config VIDEO_SAA7146_VV
> > > 	tristate
> > > 	depends on VIDEO_DEV = y || VIDEO_DEV = VIDEO_SAA7146_VV
> > > 	select VIDEOBUF_DMA_SG
> > > 	select VIDEO_SAA7146
> > > 
> > > (untested)
> > 
> > Nope, won't work.  I tried that last night.  VIDEO_DEV_SAA7146_VV
> > has too many "select"s involved, but select doesn't follow the dependency
> > chains.  IOW, as written in Documentation/kbuild/kconfig-language.txt:
> > 
> > 	select is evil.... select will by brute force set a symbol
> > 	equal to 'y' without visiting the dependencies. So abusing
> > 	select you are able to select a symbol FOO even if FOO depends
> > 	on BAR that is not set.
> 
> so ... what should we do? Remove those ~7 select VIDEO_SAA7146_VV lines 
> and replace them with depends on VIDEO_SAA7146_VV ?

Hm, the idea is that the SAA7146 driver is like a library,
and the V4L or DVB card drivers select the library functions
they need (base driver or common V4L helper functions).
The user shouldn't have to worry about those details.

But yeah, if it's not possible to do that with kbuild then
it's probably best to s/select/depends on/ for VIDEO_SAA7146_VV
and provide a meaningful help text for VIDEO_SAA7146_VV.


Johannes