Re: [v4l-dvb-maintainer] bttv build error (CONFIG_NET=n)

[Mauro Carvalho Chehab <mchehab@infradead.org>]

Randy,

> > The only reason the net stuff works, is because CONFIG_NET includes igmp.c,
> > which can't be compiled as a module.  That means ip_compute_csum() will get
> > pulled out of the lib.a file for igmp, and thus be present for the net modules
> > that use it too.  If igmp could be turned off, made a module, or stopped using
> > ip_compute_csum(), then the users of ip_compute_csum() that do depend on
> > CONFIG_NET would have the same problem as bttv does.
> 
> Thanks for the analysis and summary.
> (I'm still waiting for those lkml.org links to load... timed out)
> 
> > It seems a shame to create a new ip checksum function in the bttv driver when
> > a perfectly good one already exists and will already be present in just about
> > every kernel out there.  Honestly, how common is NET=n and VIDEO_BT848=m
> > outside of randconfig?

This might happen on embedded devices, like a set top box or a PVR,
using a bttv hardware.

> so just adding "depends on NET" should be OK then?

Seems very weird to have bttv module dependent on NET, just because a
checksum calculus function is defined there. 

One possible solution would be to move this function to another place
and having both NET, BTTV and other places selecting it.

-- 
Cheers,
Mauro