Re: Unknown symbol put_vaddr_frames when using media_build

[Mauro Carvalho Chehab <mchehab@s-opensource.com>]

Em Wed, 7 Jun 2017 22:17:50 +0200
Matthias Schwarzott <zzam@gentoo.org> escreveu:

> Am 07.06.2017 um 20:23 schrieb Mauro Carvalho Chehab:
> > Em Tue, 9 May 2017 06:56:25 +0200
> > Matthias Schwarzott <zzam@gentoo.org> escreveu:
> >   
> >> Hi!
> >>
> >> Whenever I compile the media drivers using media_build against a recent
> >> kernel, I get this message when loading them:
> >>
> >> [    5.848537] media: Linux media interface: v0.10
> >> [    5.881440] Linux video capture interface: v2.00
> >> [    5.881441] WARNING: You are using an experimental version of the
> >> media stack.
> >> ...
> >> [    6.166390] videobuf2_memops: Unknown symbol put_vaddr_frames (err 0)
> >> [    6.166394] videobuf2_memops: Unknown symbol get_vaddr_frames (err 0)
> >> [    6.166396] videobuf2_memops: Unknown symbol frame_vector_destroy (err 0)
> >> [    6.166398] videobuf2_memops: Unknown symbol frame_vector_create (err 0)
> >>
> >> That means I am not able to load any drivers being based on
> >> videobuf2_memops without manual actions.
> >>
> >> I used kernel 4.11.0, but it does not matter which kernel version
> >> exactly is used.
> >>
> >> My solution for that has been to modify mm/Kconfig of my kernel like
> >> this and then enable FRAME_VECTOR in .config  
> > 
> > Well, if you build your Kernel with VB2 compiled, you'll have it.
> >   
> Sure.
> 
> So my question is:
> How good do the kernel origin vb2 and the media_build vb2 play together?
> 
> Will modprobe always choose the media_build one?
> Or will "make install" just overwrite the original file?

make install *should* overwrite the old one. If not, then there's a problem
at the media-build makefile [1].

[1] or, if you're using a Kernel built by some distro, they choose to
store the media drivers on some other random directory that it is not
known by v4l/scripts/make_makefile.pl.


> 
> >> diff --git a/mm/Kconfig b/mm/Kconfig
> >> index 9b8fccb969dc..cfa6a80d1a0a 100644
> >> --- a/mm/Kconfig
> >> +++ b/mm/Kconfig
> >> @@ -701,7 +701,7 @@ config ZONE_DEVICE
> >>           If FS_DAX is enabled, then say Y.
> >>
> >>  config FRAME_VECTOR
> >> -       bool
> >> +       tristate "frame vector"
> >>
> >>  config ARCH_USES_HIGH_VMA_FLAGS
> >>         bool
> >>
> >> But I do not like that solution.
> >> I would prefer one of these solutions:
> >>
> >> 1. Have media_build apply its fallback the same way as for older kernels
> >> that do not even have the the FRAME_VECTOR support.
> >>
> >> 2. Get the above patch merged (plus description etc.).
> >>
> >> What do you think?  
> > 
> > (1) is probably simpler, but you would need to play with the building
> > system in order to identify if the current Kernel has it enabled or not.
> > That could be tricky.
> > 
> > I suspect people won't accept (2), as it doesn't make sense upstream.  
> 
> Well, it would be equivalent to options like CRC16 in folder lib.

You can try to submit it to mm maintainers. I'm just saying that they
may not be too receptive to a patch meant to solve an OOT build,
specially because it will open a new item at the mm menu with should
never be touched, as it is automatically selected.

Thanks,
Mauro